drivers/tty/n

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This source file includes following definitions.
gsm_fcs_add
gsm_fcs_add_block
gsm_read_ea
gsm_encode_modem
gsm_print_packet
gsm_stuff_frame
gsm_send
gsm_response
gsm_command
gsm_data_alloc
gsm_data_kick
__gsm_data_queue
gsm_data_queue
gsm_dlci_data_output
gsm_dlci_data_output_framed
gsm_dlci_data_sweep
gsm_dlci_data_kick
gsm_control_reply
gsm_process_modem
gsm_control_modem
gsm_control_rls
gsm_control_message
gsm_control_response
gsm_control_transmit
gsm_control_retransmit
gsm_control_send
gsm_control_wait
gsm_dlci_close
gsm_dlci_open
gsm_dlci_t1
gsm_dlci_begin_open
gsm_dlci_begin_close
gsm_dlci_data
gsm_dlci_command
gsm_dlci_alloc
gsm_dlci_free
dlci_get
dlci_put
gsm_dlci_release
gsm_queue
gsm0_receive
gsm1_receive
gsm_error
gsm_disconnect
gsm_cleanup_mux
gsm_activate_mux
gsm_free_mux
gsm_free_muxr
mux_get
mux_put
mux_num_to_base
mux_line_to_num
gsm_alloc_mux
gsm_copy_config_values
gsm_config
gsmld_output
gsmld_attach_gsm
gsmld_detach_gsm
gsmld_receive_buf
gsmld_flush_buffer
gsmld_close
gsmld_open
gsmld_write_wakeup
gsmld_read
gsmld_write
gsmld_poll
gsmld_ioctl
gsm_mux_net_open
gsm_mux_net_close
dlci_net_free
net_free
muxnet_get
muxnet_put
gsm_mux_net_start_xmit
gsm_mux_net_tx_timeout
gsm_mux_rx_netchar
gsm_mux_net_init
gsm_destroy_network
gsm_create_network
gsmtty_modem_update
gsm_carrier_raised
gsm_dtr_rts
gsmtty_install
gsmtty_open
gsmtty_close
gsmtty_hangup
gsmtty_write
gsmtty_write_room
gsmtty_chars_in_buffer
gsmtty_flush_buffer
gsmtty_wait_until_sent
gsmtty_tiocmget
gsmtty_tiocmset
gsmtty_ioctl
gsmtty_set_termios
gsmtty_throttle
gsmtty_unthrottle
gsmtty_break_ctl
gsmtty_cleanup
gsm_init
gsm_exit
   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * n_gsm.c GSM 0710 tty multiplexor
   4  * Copyright (c) 2009/10 Intel Corporation
   5  *
   6  *      * THIS IS A DEVELOPMENT SNAPSHOT IT IS NOT A FINAL RELEASE *
   7  *
   8  * TO DO:
   9  *      Mostly done:    ioctls for setting modes/timing
  10  *      Partly done:    hooks so you can pull off frames to non tty devs
  11  *      Restart DLCI 0 when it closes ?
  12  *      Improve the tx engine
  13  *      Resolve tx side locking by adding a queue_head and routing
  14  *              all control traffic via it
  15  *      General tidy/document
  16  *      Review the locking/move to refcounts more (mux now moved to an
  17  *              alloc/free model ready)
  18  *      Use newest tty open/close port helpers and install hooks
  19  *      What to do about power functions ?
  20  *      Termios setting and negotiation
  21  *      Do we need a 'which mux are you' ioctl to correlate mux and tty sets
  22  *
  23  */
  24 
  25 #include <linux/types.h>
  26 #include <linux/major.h>
  27 #include <linux/errno.h>
  28 #include <linux/signal.h>
  29 #include <linux/fcntl.h>
  30 #include <linux/sched/signal.h>
  31 #include <linux/interrupt.h>
  32 #include <linux/tty.h>
  33 #include <linux/ctype.h>
  34 #include <linux/mm.h>
  35 #include <linux/string.h>
  36 #include <linux/slab.h>
  37 #include <linux/poll.h>
  38 #include <linux/bitops.h>
  39 #include <linux/file.h>
  40 #include <linux/uaccess.h>
  41 #include <linux/module.h>
  42 #include <linux/timer.h>
  43 #include <linux/tty_flip.h>
  44 #include <linux/tty_driver.h>
  45 #include <linux/serial.h>
  46 #include <linux/kfifo.h>
  47 #include <linux/skbuff.h>
  48 #include <net/arp.h>
  49 #include <linux/ip.h>
  50 #include <linux/netdevice.h>
  51 #include <linux/etherdevice.h>
  52 #include <linux/gsmmux.h>
  53 
  54 static int debug;
  55 module_param(debug, int, 0600);
  56 
  57 /* Defaults: these are from the specification */
  58 
  59 #define T1      10              /* 100mS */
  60 #define T2      34              /* 333mS */
  61 #define N2      3               /* Retry 3 times */
  62 
  63 /* Use long timers for testing at low speed with debug on */
  64 #ifdef DEBUG_TIMING
  65 #define T1      100
  66 #define T2      200
  67 #endif
  68 
  69 /*
  70  * Semi-arbitrary buffer size limits. 0710 is normally run with 32-64 byte
  71  * limits so this is plenty
  72  */
  73 #define MAX_MRU 1500
  74 #define MAX_MTU 1500
  75 #define GSM_NET_TX_TIMEOUT (HZ*10)
  76 
  77 /**
  78  *      struct gsm_mux_net      -       network interface
  79  *      @struct gsm_dlci* dlci
  80  *
  81  *      Created when net interface is initialized.
  82  **/
  83 struct gsm_mux_net {
  84         struct kref ref;
  85         struct gsm_dlci *dlci;
  86 };
  87 
  88 /*
  89  *      Each block of data we have queued to go out is in the form of
  90  *      a gsm_msg which holds everything we need in a link layer independent
  91  *      format
  92  */
  93 
  94 struct gsm_msg {
  95         struct list_head list;
  96         u8 addr;                /* DLCI address + flags */
  97         u8 ctrl;                /* Control byte + flags */
  98         unsigned int len;       /* Length of data block (can be zero) */
  99         unsigned char *data;    /* Points into buffer but not at the start */
 100         unsigned char buffer[0];
 101 };
 102 
 103 /*
 104  *      Each active data link has a gsm_dlci structure associated which ties
 105  *      the link layer to an optional tty (if the tty side is open). To avoid
 106  *      complexity right now these are only ever freed up when the mux is
 107  *      shut down.
 108  *
 109  *      At the moment we don't free DLCI objects until the mux is torn down
 110  *      this avoid object life time issues but might be worth review later.
 111  */
 112 
 113 struct gsm_dlci {
 114         struct gsm_mux *gsm;
 115         int addr;
 116         int state;
 117 #define DLCI_CLOSED             0
 118 #define DLCI_OPENING            1       /* Sending SABM not seen UA */
 119 #define DLCI_OPEN               2       /* SABM/UA complete */
 120 #define DLCI_CLOSING            3       /* Sending DISC not seen UA/DM */
 121         struct mutex mutex;
 122 
 123         /* Link layer */
 124         int mode;
 125 #define DLCI_MODE_ABM           0       /* Normal Asynchronous Balanced Mode */
 126 #define DLCI_MODE_ADM           1       /* Asynchronous Disconnected Mode */
 127         spinlock_t lock;        /* Protects the internal state */
 128         struct timer_list t1;   /* Retransmit timer for SABM and UA */
 129         int retries;
 130         /* Uplink tty if active */
 131         struct tty_port port;   /* The tty bound to this DLCI if there is one */
 132         struct kfifo *fifo;     /* Queue fifo for the DLCI */
 133         struct kfifo _fifo;     /* For new fifo API porting only */
 134         int adaption;           /* Adaption layer in use */
 135         int prev_adaption;
 136         u32 modem_rx;           /* Our incoming virtual modem lines */
 137         u32 modem_tx;           /* Our outgoing modem lines */
 138         int dead;               /* Refuse re-open */
 139         /* Flow control */
 140         int throttled;          /* Private copy of throttle state */
 141         int constipated;        /* Throttle status for outgoing */
 142         /* Packetised I/O */
 143         struct sk_buff *skb;    /* Frame being sent */
 144         struct sk_buff_head skb_list;   /* Queued frames */
 145         /* Data handling callback */
 146         void (*data)(struct gsm_dlci *dlci, const u8 *data, int len);
 147         void (*prev_data)(struct gsm_dlci *dlci, const u8 *data, int len);
 148         struct net_device *net; /* network interface, if created */
 149 };
 150 
 151 /* DLCI 0, 62/63 are special or reserved see gsmtty_open */
 152 
 153 #define NUM_DLCI                64
 154 
 155 /*
 156  *      DLCI 0 is used to pass control blocks out of band of the data
 157  *      flow (and with a higher link priority). One command can be outstanding
 158  *      at a time and we use this structure to manage them. They are created
 159  *      and destroyed by the user context, and updated by the receive paths
 160  *      and timers
 161  */
 162 
 163 struct gsm_control {
 164         u8 cmd;         /* Command we are issuing */
 165         u8 *data;       /* Data for the command in case we retransmit */
 166         int len;        /* Length of block for retransmission */
 167         int done;       /* Done flag */
 168         int error;      /* Error if any */
 169 };
 170 
 171 /*
 172  *      Each GSM mux we have is represented by this structure. If we are
 173  *      operating as an ldisc then we use this structure as our ldisc
 174  *      state. We need to sort out lifetimes and locking with respect
 175  *      to the gsm mux array. For now we don't free DLCI objects that
 176  *      have been instantiated until the mux itself is terminated.
 177  *
 178  *      To consider further: tty open versus mux shutdown.
 179  */
 180 
 181 struct gsm_mux {
 182         struct tty_struct *tty;         /* The tty our ldisc is bound to */
 183         spinlock_t lock;
 184         struct mutex mutex;
 185         unsigned int num;
 186         struct kref ref;
 187 
 188         /* Events on the GSM channel */
 189         wait_queue_head_t event;
 190 
 191         /* Bits for GSM mode decoding */
 192 
 193         /* Framing Layer */
 194         unsigned char *buf;
 195         int state;
 196 #define GSM_SEARCH              0
 197 #define GSM_START               1
 198 #define GSM_ADDRESS             2
 199 #define GSM_CONTROL             3
 200 #define GSM_LEN                 4
 201 #define GSM_DATA                5
 202 #define GSM_FCS                 6
 203 #define GSM_OVERRUN             7
 204 #define GSM_LEN0                8
 205 #define GSM_LEN1                9
 206 #define GSM_SSOF                10
 207         unsigned int len;
 208         unsigned int address;
 209         unsigned int count;
 210         int escape;
 211         int encoding;
 212         u8 control;
 213         u8 fcs;
 214         u8 received_fcs;
 215         u8 *txframe;                    /* TX framing buffer */
 216 
 217         /* Methods for the receiver side */
 218         void (*receive)(struct gsm_mux *gsm, u8 ch);
 219         void (*error)(struct gsm_mux *gsm, u8 ch, u8 flag);
 220         /* And transmit side */
 221         int (*output)(struct gsm_mux *mux, u8 *data, int len);
 222 
 223         /* Link Layer */
 224         unsigned int mru;
 225         unsigned int mtu;
 226         int initiator;                  /* Did we initiate connection */
 227         int dead;                       /* Has the mux been shut down */
 228         struct gsm_dlci *dlci[NUM_DLCI];
 229         int constipated;                /* Asked by remote to shut up */
 230 
 231         spinlock_t tx_lock;
 232         unsigned int tx_bytes;          /* TX data outstanding */
 233 #define TX_THRESH_HI            8192
 234 #define TX_THRESH_LO            2048
 235         struct list_head tx_list;       /* Pending data packets */
 236 
 237         /* Control messages */
 238         struct timer_list t2_timer;     /* Retransmit timer for commands */
 239         int cretries;                   /* Command retry counter */
 240         struct gsm_control *pending_cmd;/* Our current pending command */
 241         spinlock_t control_lock;        /* Protects the pending command */
 242 
 243         /* Configuration */
 244         int adaption;           /* 1 or 2 supported */
 245         u8 ftype;               /* UI or UIH */
 246         int t1, t2;             /* Timers in 1/100th of a sec */
 247         int n2;                 /* Retry count */
 248 
 249         /* Statistics (not currently exposed) */
 250         unsigned long bad_fcs;
 251         unsigned long malformed;
 252         unsigned long io_error;
 253         unsigned long bad_size;
 254         unsigned long unsupported;
 255 };
 256 
 257 
 258 /*
 259  *      Mux objects - needed so that we can translate a tty index into the
 260  *      relevant mux and DLCI.
 261  */
 262 
 263 #define MAX_MUX         4                       /* 256 minors */
 264 static struct gsm_mux *gsm_mux[MAX_MUX];        /* GSM muxes */
 265 static spinlock_t gsm_mux_lock;
 266 
 267 static struct tty_driver *gsm_tty_driver;
 268 
 269 /*
 270  *      This section of the driver logic implements the GSM encodings
 271  *      both the basic and the 'advanced'. Reliable transport is not
 272  *      supported.
 273  */
 274 
 275 #define CR                      0x02
 276 #define EA                      0x01
 277 #define PF                      0x10
 278 
 279 /* I is special: the rest are ..*/
 280 #define RR                      0x01
 281 #define UI                      0x03
 282 #define RNR                     0x05
 283 #define REJ                     0x09
 284 #define DM                      0x0F
 285 #define SABM                    0x2F
 286 #define DISC                    0x43
 287 #define UA                      0x63
 288 #define UIH                     0xEF
 289 
 290 /* Channel commands */
 291 #define CMD_NSC                 0x09
 292 #define CMD_TEST                0x11
 293 #define CMD_PSC                 0x21
 294 #define CMD_RLS                 0x29
 295 #define CMD_FCOFF               0x31
 296 #define CMD_PN                  0x41
 297 #define CMD_RPN                 0x49
 298 #define CMD_FCON                0x51
 299 #define CMD_CLD                 0x61
 300 #define CMD_SNC                 0x69
 301 #define CMD_MSC                 0x71
 302 
 303 /* Virtual modem bits */
 304 #define MDM_FC                  0x01
 305 #define MDM_RTC                 0x02
 306 #define MDM_RTR                 0x04
 307 #define MDM_IC                  0x20
 308 #define MDM_DV                  0x40
 309 
 310 #define GSM0_SOF                0xF9
 311 #define GSM1_SOF                0x7E
 312 #define GSM1_ESCAPE             0x7D
 313 #define GSM1_ESCAPE_BITS        0x20
 314 #define XON                     0x11
 315 #define XOFF                    0x13
 316 
 317 static const struct tty_port_operations gsm_port_ops;
 318 
 319 /*
 320  *      CRC table for GSM 0710
 321  */
 322 
 323 static const u8 gsm_fcs8[256] = {
 324         0x00, 0x91, 0xE3, 0x72, 0x07, 0x96, 0xE4, 0x75,
 325         0x0E, 0x9F, 0xED, 0x7C, 0x09, 0x98, 0xEA, 0x7B,
 326         0x1C, 0x8D, 0xFF, 0x6E, 0x1B, 0x8A, 0xF8, 0x69,
 327         0x12, 0x83, 0xF1, 0x60, 0x15, 0x84, 0xF6, 0x67,
 328         0x38, 0xA9, 0xDB, 0x4A, 0x3F, 0xAE, 0xDC, 0x4D,
 329         0x36, 0xA7, 0xD5, 0x44, 0x31, 0xA0, 0xD2, 0x43,
 330         0x24, 0xB5, 0xC7, 0x56, 0x23, 0xB2, 0xC0, 0x51,
 331         0x2A, 0xBB, 0xC9, 0x58, 0x2D, 0xBC, 0xCE, 0x5F,
 332         0x70, 0xE1, 0x93, 0x02, 0x77, 0xE6, 0x94, 0x05,
 333         0x7E, 0xEF, 0x9D, 0x0C, 0x79, 0xE8, 0x9A, 0x0B,
 334         0x6C, 0xFD, 0x8F, 0x1E, 0x6B, 0xFA, 0x88, 0x19,
 335         0x62, 0xF3, 0x81, 0x10, 0x65, 0xF4, 0x86, 0x17,
 336         0x48, 0xD9, 0xAB, 0x3A, 0x4F, 0xDE, 0xAC, 0x3D,
 337         0x46, 0xD7, 0xA5, 0x34, 0x41, 0xD0, 0xA2, 0x33,
 338         0x54, 0xC5, 0xB7, 0x26, 0x53, 0xC2, 0xB0, 0x21,
 339         0x5A, 0xCB, 0xB9, 0x28, 0x5D, 0xCC, 0xBE, 0x2F,
 340         0xE0, 0x71, 0x03, 0x92, 0xE7, 0x76, 0x04, 0x95,
 341         0xEE, 0x7F, 0x0D, 0x9C, 0xE9, 0x78, 0x0A, 0x9B,
 342         0xFC, 0x6D, 0x1F, 0x8E, 0xFB, 0x6A, 0x18, 0x89,
 343         0xF2, 0x63, 0x11, 0x80, 0xF5, 0x64, 0x16, 0x87,
 344         0xD8, 0x49, 0x3B, 0xAA, 0xDF, 0x4E, 0x3C, 0xAD,
 345         0xD6, 0x47, 0x35, 0xA4, 0xD1, 0x40, 0x32, 0xA3,
 346         0xC4, 0x55, 0x27, 0xB6, 0xC3, 0x52, 0x20, 0xB1,
 347         0xCA, 0x5B, 0x29, 0xB8, 0xCD, 0x5C, 0x2E, 0xBF,
 348         0x90, 0x01, 0x73, 0xE2, 0x97, 0x06, 0x74, 0xE5,
 349         0x9E, 0x0F, 0x7D, 0xEC, 0x99, 0x08, 0x7A, 0xEB,
 350         0x8C, 0x1D, 0x6F, 0xFE, 0x8B, 0x1A, 0x68, 0xF9,
 351         0x82, 0x13, 0x61, 0xF0, 0x85, 0x14, 0x66, 0xF7,
 352         0xA8, 0x39, 0x4B, 0xDA, 0xAF, 0x3E, 0x4C, 0xDD,
 353         0xA6, 0x37, 0x45, 0xD4, 0xA1, 0x30, 0x42, 0xD3,
 354         0xB4, 0x25, 0x57, 0xC6, 0xB3, 0x22, 0x50, 0xC1,
 355         0xBA, 0x2B, 0x59, 0xC8, 0xBD, 0x2C, 0x5E, 0xCF
 356 };
 357 
 358 #define INIT_FCS        0xFF
 359 #define GOOD_FCS        0xCF
 360 
 361 /**
 362  *      gsm_fcs_add     -       update FCS
 363  *      @fcs: Current FCS
 364  *      @c: Next data
 365  *
 366  *      Update the FCS to include c. Uses the algorithm in the specification
 367  *      notes.
 368  */
 369 
 370 static inline u8 gsm_fcs_add(u8 fcs, u8 c)
 371 {
 372         return gsm_fcs8[fcs ^ c];
 373 }
 374 
 375 /**
 376  *      gsm_fcs_add_block       -       update FCS for a block
 377  *      @fcs: Current FCS
 378  *      @c: buffer of data
 379  *      @len: length of buffer
 380  *
 381  *      Update the FCS to include c. Uses the algorithm in the specification
 382  *      notes.
 383  */
 384 
 385 static inline u8 gsm_fcs_add_block(u8 fcs, u8 *c, int len)
 386 {
 387         while (len--)
 388                 fcs = gsm_fcs8[fcs ^ *c++];
 389         return fcs;
 390 }
 391 
 392 /**
 393  *      gsm_read_ea             -       read a byte into an EA
 394  *      @val: variable holding value
 395  *      c: byte going into the EA
 396  *
 397  *      Processes one byte of an EA. Updates the passed variable
 398  *      and returns 1 if the EA is now completely read
 399  */
 400 
 401 static int gsm_read_ea(unsigned int *val, u8 c)
 402 {
 403         /* Add the next 7 bits into the value */
 404         *val <<= 7;
 405         *val |= c >> 1;
 406         /* Was this the last byte of the EA 1 = yes*/
 407         return c & EA;
 408 }
 409 
 410 /**
 411  *      gsm_encode_modem        -       encode modem data bits
 412  *      @dlci: DLCI to encode from
 413  *
 414  *      Returns the correct GSM encoded modem status bits (6 bit field) for
 415  *      the current status of the DLCI and attached tty object
 416  */
 417 
 418 static u8 gsm_encode_modem(const struct gsm_dlci *dlci)
 419 {
 420         u8 modembits = 0;
 421         /* FC is true flow control not modem bits */
 422         if (dlci->throttled)
 423                 modembits |= MDM_FC;
 424         if (dlci->modem_tx & TIOCM_DTR)
 425                 modembits |= MDM_RTC;
 426         if (dlci->modem_tx & TIOCM_RTS)
 427                 modembits |= MDM_RTR;
 428         if (dlci->modem_tx & TIOCM_RI)
 429                 modembits |= MDM_IC;
 430         if (dlci->modem_tx & TIOCM_CD)
 431                 modembits |= MDM_DV;
 432         return modembits;
 433 }
 434 
 435 /**
 436  *      gsm_print_packet        -       display a frame for debug
 437  *      @hdr: header to print before decode
 438  *      @addr: address EA from the frame
 439  *      @cr: C/R bit from the frame
 440  *      @control: control including PF bit
 441  *      @data: following data bytes
 442  *      @dlen: length of data
 443  *
 444  *      Displays a packet in human readable format for debugging purposes. The
 445  *      style is based on amateur radio LAP-B dump display.
 446  */
 447 
 448 static void gsm_print_packet(const char *hdr, int addr, int cr,
 449                                         u8 control, const u8 *data, int dlen)
 450 {
 451         if (!(debug & 1))
 452                 return;
 453 
 454         pr_info("%s %d) %c: ", hdr, addr, "RC"[cr]);
 455 
 456         switch (control & ~PF) {
 457         case SABM:
 458                 pr_cont("SABM");
 459                 break;
 460         case UA:
 461                 pr_cont("UA");
 462                 break;
 463         case DISC:
 464                 pr_cont("DISC");
 465                 break;
 466         case DM:
 467                 pr_cont("DM");
 468                 break;
 469         case UI:
 470                 pr_cont("UI");
 471                 break;
 472         case UIH:
 473                 pr_cont("UIH");
 474                 break;
 475         default:
 476                 if (!(control & 0x01)) {
 477                         pr_cont("I N(S)%d N(R)%d",
 478                                 (control & 0x0E) >> 1, (control & 0xE0) >> 5);
 479                 } else switch (control & 0x0F) {
 480                         case RR:
 481                                 pr_cont("RR(%d)", (control & 0xE0) >> 5);
 482                                 break;
 483                         case RNR:
 484                                 pr_cont("RNR(%d)", (control & 0xE0) >> 5);
 485                                 break;
 486                         case REJ:
 487                                 pr_cont("REJ(%d)", (control & 0xE0) >> 5);
 488                                 break;
 489                         default:
 490                                 pr_cont("[%02X]", control);
 491                 }
 492         }
 493 
 494         if (control & PF)
 495                 pr_cont("(P)");
 496         else
 497                 pr_cont("(F)");
 498 
 499         if (dlen) {
 500                 int ct = 0;
 501                 while (dlen--) {
 502                         if (ct % 8 == 0) {
 503                                 pr_cont("\n");
 504                                 pr_debug("    ");
 505                         }
 506                         pr_cont("%02X ", *data++);
 507                         ct++;
 508                 }
 509         }
 510         pr_cont("\n");
 511 }
 512 
 513 
 514 /*
 515  *      Link level transmission side
 516  */
 517 
 518 /**
 519  *      gsm_stuff_packet        -       bytestuff a packet
 520  *      @ibuf: input
 521  *      @obuf: output
 522  *      @len: length of input
 523  *
 524  *      Expand a buffer by bytestuffing it. The worst case size change
 525  *      is doubling and the caller is responsible for handing out
 526  *      suitable sized buffers.
 527  */
 528 
 529 static int gsm_stuff_frame(const u8 *input, u8 *output, int len)
 530 {
 531         int olen = 0;
 532         while (len--) {
 533                 if (*input == GSM1_SOF || *input == GSM1_ESCAPE
 534                     || *input == XON || *input == XOFF) {
 535                         *output++ = GSM1_ESCAPE;
 536                         *output++ = *input++ ^ GSM1_ESCAPE_BITS;
 537                         olen++;
 538                 } else
 539                         *output++ = *input++;
 540                 olen++;
 541         }
 542         return olen;
 543 }
 544 
 545 /**
 546  *      gsm_send        -       send a control frame
 547  *      @gsm: our GSM mux
 548  *      @addr: address for control frame
 549  *      @cr: command/response bit
 550  *      @control:  control byte including PF bit
 551  *
 552  *      Format up and transmit a control frame. These do not go via the
 553  *      queueing logic as they should be transmitted ahead of data when
 554  *      they are needed.
 555  *
 556  *      FIXME: Lock versus data TX path
 557  */
 558 
 559 static void gsm_send(struct gsm_mux *gsm, int addr, int cr, int control)
 560 {
 561         int len;
 562         u8 cbuf[10];
 563         u8 ibuf[3];
 564 
 565         switch (gsm->encoding) {
 566         case 0:
 567                 cbuf[0] = GSM0_SOF;
 568                 cbuf[1] = (addr << 2) | (cr << 1) | EA;
 569                 cbuf[2] = control;
 570                 cbuf[3] = EA;   /* Length of data = 0 */
 571                 cbuf[4] = 0xFF - gsm_fcs_add_block(INIT_FCS, cbuf + 1, 3);
 572                 cbuf[5] = GSM0_SOF;
 573                 len = 6;
 574                 break;
 575         case 1:
 576         case 2:
 577                 /* Control frame + packing (but not frame stuffing) in mode 1 */
 578                 ibuf[0] = (addr << 2) | (cr << 1) | EA;
 579                 ibuf[1] = control;
 580                 ibuf[2] = 0xFF - gsm_fcs_add_block(INIT_FCS, ibuf, 2);
 581                 /* Stuffing may double the size worst case */
 582                 len = gsm_stuff_frame(ibuf, cbuf + 1, 3);
 583                 /* Now add the SOF markers */
 584                 cbuf[0] = GSM1_SOF;
 585                 cbuf[len + 1] = GSM1_SOF;
 586                 /* FIXME: we can omit the lead one in many cases */
 587                 len += 2;
 588                 break;
 589         default:
 590                 WARN_ON(1);
 591                 return;
 592         }
 593         gsm->output(gsm, cbuf, len);
 594         gsm_print_packet("-->", addr, cr, control, NULL, 0);
 595 }
 596 
 597 /**
 598  *      gsm_response    -       send a control response
 599  *      @gsm: our GSM mux
 600  *      @addr: address for control frame
 601  *      @control:  control byte including PF bit
 602  *
 603  *      Format up and transmit a link level response frame.
 604  */
 605 
 606 static inline void gsm_response(struct gsm_mux *gsm, int addr, int control)
 607 {
 608         gsm_send(gsm, addr, 0, control);
 609 }
 610 
 611 /**
 612  *      gsm_command     -       send a control command
 613  *      @gsm: our GSM mux
 614  *      @addr: address for control frame
 615  *      @control:  control byte including PF bit
 616  *
 617  *      Format up and transmit a link level command frame.
 618  */
 619 
 620 static inline void gsm_command(struct gsm_mux *gsm, int addr, int control)
 621 {
 622         gsm_send(gsm, addr, 1, control);
 623 }
 624 
 625 /* Data transmission */
 626 
 627 #define HDR_LEN         6       /* ADDR CTRL [LEN.2] DATA FCS */
 628 
 629 /**
 630  *      gsm_data_alloc          -       allocate data frame
 631  *      @gsm: GSM mux
 632  *      @addr: DLCI address
 633  *      @len: length excluding header and FCS
 634  *      @ctrl: control byte
 635  *
 636  *      Allocate a new data buffer for sending frames with data. Space is left
 637  *      at the front for header bytes but that is treated as an implementation
 638  *      detail and not for the high level code to use
 639  */
 640 
 641 static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
 642                                                                 u8 ctrl)
 643 {
 644         struct gsm_msg *m = kmalloc(sizeof(struct gsm_msg) + len + HDR_LEN,
 645                                                                 GFP_ATOMIC);
 646         if (m == NULL)
 647                 return NULL;
 648         m->data = m->buffer + HDR_LEN - 1;      /* Allow for FCS */
 649         m->len = len;
 650         m->addr = addr;
 651         m->ctrl = ctrl;
 652         INIT_LIST_HEAD(&m->list);
 653         return m;
 654 }
 655 
 656 /**
 657  *      gsm_data_kick           -       poke the queue
 658  *      @gsm: GSM Mux
 659  *
 660  *      The tty device has called us to indicate that room has appeared in
 661  *      the transmit queue. Ram more data into the pipe if we have any
 662  *      If we have been flow-stopped by a CMD_FCOFF, then we can only
 663  *      send messages on DLCI0 until CMD_FCON
 664  *
 665  *      FIXME: lock against link layer control transmissions
 666  */
 667 
 668 static void gsm_data_kick(struct gsm_mux *gsm)
 669 {
 670         struct gsm_msg *msg, *nmsg;
 671         int len;
 672         int skip_sof = 0;
 673 
 674         list_for_each_entry_safe(msg, nmsg, &gsm->tx_list, list) {
 675                 if (gsm->constipated && msg->addr)
 676                         continue;
 677                 if (gsm->encoding != 0) {
 678                         gsm->txframe[0] = GSM1_SOF;
 679                         len = gsm_stuff_frame(msg->data,
 680                                                 gsm->txframe + 1, msg->len);
 681                         gsm->txframe[len + 1] = GSM1_SOF;
 682                         len += 2;
 683                 } else {
 684                         gsm->txframe[0] = GSM0_SOF;
 685                         memcpy(gsm->txframe + 1 , msg->data, msg->len);
 686                         gsm->txframe[msg->len + 1] = GSM0_SOF;
 687                         len = msg->len + 2;
 688                 }
 689 
 690                 if (debug & 4)
 691                         print_hex_dump_bytes("gsm_data_kick: ",
 692                                              DUMP_PREFIX_OFFSET,
 693                                              gsm->txframe, len);
 694 
 695                 if (gsm->output(gsm, gsm->txframe + skip_sof,
 696                                                 len - skip_sof) < 0)
 697                         break;
 698                 /* FIXME: Can eliminate one SOF in many more cases */
 699                 gsm->tx_bytes -= msg->len;
 700                 /* For a burst of frames skip the extra SOF within the
 701                    burst */
 702                 skip_sof = 1;
 703 
 704                 list_del(&msg->list);
 705                 kfree(msg);
 706         }
 707 }
 708 
 709 /**
 710  *      __gsm_data_queue                -       queue a UI or UIH frame
 711  *      @dlci: DLCI sending the data
 712  *      @msg: message queued
 713  *
 714  *      Add data to the transmit queue and try and get stuff moving
 715  *      out of the mux tty if not already doing so. The Caller must hold
 716  *      the gsm tx lock.
 717  */
 718 
 719 static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
 720 {
 721         struct gsm_mux *gsm = dlci->gsm;
 722         u8 *dp = msg->data;
 723         u8 *fcs = dp + msg->len;
 724 
 725         /* Fill in the header */
 726         if (gsm->encoding == 0) {
 727                 if (msg->len < 128)
 728                         *--dp = (msg->len << 1) | EA;
 729                 else {
 730                         *--dp = (msg->len >> 7);        /* bits 7 - 15 */
 731                         *--dp = (msg->len & 127) << 1;  /* bits 0 - 6 */
 732                 }
 733         }
 734 
 735         *--dp = msg->ctrl;
 736         if (gsm->initiator)
 737                 *--dp = (msg->addr << 2) | 2 | EA;
 738         else
 739                 *--dp = (msg->addr << 2) | EA;
 740         *fcs = gsm_fcs_add_block(INIT_FCS, dp , msg->data - dp);
 741         /* Ugly protocol layering violation */
 742         if (msg->ctrl == UI || msg->ctrl == (UI|PF))
 743                 *fcs = gsm_fcs_add_block(*fcs, msg->data, msg->len);
 744         *fcs = 0xFF - *fcs;
 745 
 746         gsm_print_packet("Q> ", msg->addr, gsm->initiator, msg->ctrl,
 747                                                         msg->data, msg->len);
 748 
 749         /* Move the header back and adjust the length, also allow for the FCS
 750            now tacked on the end */
 751         msg->len += (msg->data - dp) + 1;
 752         msg->data = dp;
 753 
 754         /* Add to the actual output queue */
 755         list_add_tail(&msg->list, &gsm->tx_list);
 756         gsm->tx_bytes += msg->len;
 757         gsm_data_kick(gsm);
 758 }
 759 
 760 /**
 761  *      gsm_data_queue          -       queue a UI or UIH frame
 762  *      @dlci: DLCI sending the data
 763  *      @msg: message queued
 764  *
 765  *      Add data to the transmit queue and try and get stuff moving
 766  *      out of the mux tty if not already doing so. Take the
 767  *      the gsm tx lock and dlci lock.
 768  */
 769 
 770 static void gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
 771 {
 772         unsigned long flags;
 773         spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
 774         __gsm_data_queue(dlci, msg);
 775         spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
 776 }
 777 
 778 /**
 779  *      gsm_dlci_data_output    -       try and push data out of a DLCI
 780  *      @gsm: mux
 781  *      @dlci: the DLCI to pull data from
 782  *
 783  *      Pull data from a DLCI and send it into the transmit queue if there
 784  *      is data. Keep to the MRU of the mux. This path handles the usual tty
 785  *      interface which is a byte stream with optional modem data.
 786  *
 787  *      Caller must hold the tx_lock of the mux.
 788  */
 789 
 790 static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci)
 791 {
 792         struct gsm_msg *msg;
 793         u8 *dp;
 794         int len, total_size, size;
 795         int h = dlci->adaption - 1;
 796 
 797         total_size = 0;
 798         while (1) {
 799                 len = kfifo_len(dlci->fifo);
 800                 if (len == 0)
 801                         return total_size;
 802 
 803                 /* MTU/MRU count only the data bits */
 804                 if (len > gsm->mtu)
 805                         len = gsm->mtu;
 806 
 807                 size = len + h;
 808 
 809                 msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
 810                 /* FIXME: need a timer or something to kick this so it can't
 811                    get stuck with no work outstanding and no buffer free */
 812                 if (msg == NULL)
 813                         return -ENOMEM;
 814                 dp = msg->data;
 815                 switch (dlci->adaption) {
 816                 case 1: /* Unstructured */
 817                         break;
 818                 case 2: /* Unstructed with modem bits.
 819                 Always one byte as we never send inline break data */
 820                         *dp++ = gsm_encode_modem(dlci);
 821                         break;
 822                 }
 823                 WARN_ON(kfifo_out_locked(dlci->fifo, dp , len, &dlci->lock) != len);
 824                 __gsm_data_queue(dlci, msg);
 825                 total_size += size;
 826         }
 827         /* Bytes of data we used up */
 828         return total_size;
 829 }
 830 
 831 /**
 832  *      gsm_dlci_data_output_framed  -  try and push data out of a DLCI
 833  *      @gsm: mux
 834  *      @dlci: the DLCI to pull data from
 835  *
 836  *      Pull data from a DLCI and send it into the transmit queue if there
 837  *      is data. Keep to the MRU of the mux. This path handles framed data
 838  *      queued as skbuffs to the DLCI.
 839  *
 840  *      Caller must hold the tx_lock of the mux.
 841  */
 842 
 843 static int gsm_dlci_data_output_framed(struct gsm_mux *gsm,
 844                                                 struct gsm_dlci *dlci)
 845 {
 846         struct gsm_msg *msg;
 847         u8 *dp;
 848         int len, size;
 849         int last = 0, first = 0;
 850         int overhead = 0;
 851 
 852         /* One byte per frame is used for B/F flags */
 853         if (dlci->adaption == 4)
 854                 overhead = 1;
 855 
 856         /* dlci->skb is locked by tx_lock */
 857         if (dlci->skb == NULL) {
 858                 dlci->skb = skb_dequeue_tail(&dlci->skb_list);
 859                 if (dlci->skb == NULL)
 860                         return 0;
 861                 first = 1;
 862         }
 863         len = dlci->skb->len + overhead;
 864 
 865         /* MTU/MRU count only the data bits */
 866         if (len > gsm->mtu) {
 867                 if (dlci->adaption == 3) {
 868                         /* Over long frame, bin it */
 869                         dev_kfree_skb_any(dlci->skb);
 870                         dlci->skb = NULL;
 871                         return 0;
 872                 }
 873                 len = gsm->mtu;
 874         } else
 875                 last = 1;
 876 
 877         size = len + overhead;
 878         msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
 879 
 880         /* FIXME: need a timer or something to kick this so it can't
 881            get stuck with no work outstanding and no buffer free */
 882         if (msg == NULL) {
 883                 skb_queue_tail(&dlci->skb_list, dlci->skb);
 884                 dlci->skb = NULL;
 885                 return -ENOMEM;
 886         }
 887         dp = msg->data;
 888 
 889         if (dlci->adaption == 4) { /* Interruptible framed (Packetised Data) */
 890                 /* Flag byte to carry the start/end info */
 891                 *dp++ = last << 7 | first << 6 | 1;     /* EA */
 892                 len--;
 893         }
 894         memcpy(dp, dlci->skb->data, len);
 895         skb_pull(dlci->skb, len);
 896         __gsm_data_queue(dlci, msg);
 897         if (last) {
 898                 dev_kfree_skb_any(dlci->skb);
 899                 dlci->skb = NULL;
 900         }
 901         return size;
 902 }
 903 
 904 /**
 905  *      gsm_dlci_data_sweep             -       look for data to send
 906  *      @gsm: the GSM mux
 907  *
 908  *      Sweep the GSM mux channels in priority order looking for ones with
 909  *      data to send. We could do with optimising this scan a bit. We aim
 910  *      to fill the queue totally or up to TX_THRESH_HI bytes. Once we hit
 911  *      TX_THRESH_LO we get called again
 912  *
 913  *      FIXME: We should round robin between groups and in theory you can
 914  *      renegotiate DLCI priorities with optional stuff. Needs optimising.
 915  */
 916 
 917 static void gsm_dlci_data_sweep(struct gsm_mux *gsm)
 918 {
 919         int len;
 920         /* Priority ordering: We should do priority with RR of the groups */
 921         int i = 1;
 922 
 923         while (i < NUM_DLCI) {
 924                 struct gsm_dlci *dlci;
 925 
 926                 if (gsm->tx_bytes > TX_THRESH_HI)
 927                         break;
 928                 dlci = gsm->dlci[i];
 929                 if (dlci == NULL || dlci->constipated) {
 930                         i++;
 931                         continue;
 932                 }
 933                 if (dlci->adaption < 3 && !dlci->net)
 934                         len = gsm_dlci_data_output(gsm, dlci);
 935                 else
 936                         len = gsm_dlci_data_output_framed(gsm, dlci);
 937                 if (len < 0)
 938                         break;
 939                 /* DLCI empty - try the next */
 940                 if (len == 0)
 941                         i++;
 942         }
 943 }
 944 
 945 /**
 946  *      gsm_dlci_data_kick      -       transmit if possible
 947  *      @dlci: DLCI to kick
 948  *
 949  *      Transmit data from this DLCI if the queue is empty. We can't rely on
 950  *      a tty wakeup except when we filled the pipe so we need to fire off
 951  *      new data ourselves in other cases.
 952  */
 953 
 954 static void gsm_dlci_data_kick(struct gsm_dlci *dlci)
 955 {
 956         unsigned long flags;
 957         int sweep;
 958 
 959         if (dlci->constipated)
 960                 return;
 961 
 962         spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
 963         /* If we have nothing running then we need to fire up */
 964         sweep = (dlci->gsm->tx_bytes < TX_THRESH_LO);
 965         if (dlci->gsm->tx_bytes == 0) {
 966                 if (dlci->net)
 967                         gsm_dlci_data_output_framed(dlci->gsm, dlci);
 968                 else
 969                         gsm_dlci_data_output(dlci->gsm, dlci);
 970         }
 971         if (sweep)
 972                 gsm_dlci_data_sweep(dlci->gsm);
 973         spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
 974 }
 975 
 976 /*
 977  *      Control message processing
 978  */
 979 
 980 
 981 /**
 982  *      gsm_control_reply       -       send a response frame to a control
 983  *      @gsm: gsm channel
 984  *      @cmd: the command to use
 985  *      @data: data to follow encoded info
 986  *      @dlen: length of data
 987  *
 988  *      Encode up and queue a UI/UIH frame containing our response.
 989  */
 990 
 991 static void gsm_control_reply(struct gsm_mux *gsm, int cmd, const u8 *data,
 992                                         int dlen)
 993 {
 994         struct gsm_msg *msg;
 995         msg = gsm_data_alloc(gsm, 0, dlen + 2, gsm->ftype);
 996         if (msg == NULL)
 997                 return;
 998         msg->data[0] = (cmd & 0xFE) << 1 | EA;  /* Clear C/R */
 999         msg->data[1] = (dlen << 1) | EA;
1000         memcpy(msg->data + 2, data, dlen);
1001         gsm_data_queue(gsm->dlci[0], msg);
1002 }
1003 
1004 /**
1005  *      gsm_process_modem       -       process received modem status
1006  *      @tty: virtual tty bound to the DLCI
1007  *      @dlci: DLCI to affect
1008  *      @modem: modem bits (full EA)
1009  *
1010  *      Used when a modem control message or line state inline in adaption
1011  *      layer 2 is processed. Sort out the local modem state and throttles
1012  */
1013 
1014 static void gsm_process_modem(struct tty_struct *tty, struct gsm_dlci *dlci,
1015                                                         u32 modem, int clen)
1016 {
1017         int  mlines = 0;
1018         u8 brk = 0;
1019         int fc;
1020 
1021         /* The modem status command can either contain one octet (v.24 signals)
1022            or two octets (v.24 signals + break signals). The length field will
1023            either be 2 or 3 respectively. This is specified in section
1024            5.4.6.3.7 of the  27.010 mux spec. */
1025 
1026         if (clen == 2)
1027                 modem = modem & 0x7f;
1028         else {
1029                 brk = modem & 0x7f;
1030                 modem = (modem >> 7) & 0x7f;
1031         }
1032 
1033         /* Flow control/ready to communicate */
1034         fc = (modem & MDM_FC) || !(modem & MDM_RTR);
1035         if (fc && !dlci->constipated) {
1036                 /* Need to throttle our output on this device */
1037                 dlci->constipated = 1;
1038         } else if (!fc && dlci->constipated) {
1039                 dlci->constipated = 0;
1040                 gsm_dlci_data_kick(dlci);
1041         }
1042 
1043         /* Map modem bits */
1044         if (modem & MDM_RTC)
1045                 mlines |= TIOCM_DSR | TIOCM_DTR;
1046         if (modem & MDM_RTR)
1047                 mlines |= TIOCM_RTS | TIOCM_CTS;
1048         if (modem & MDM_IC)
1049                 mlines |= TIOCM_RI;
1050         if (modem & MDM_DV)
1051                 mlines |= TIOCM_CD;
1052 
1053         /* Carrier drop -> hangup */
1054         if (tty) {
1055                 if ((mlines & TIOCM_CD) == 0 && (dlci->modem_rx & TIOCM_CD))
1056                         if (!C_CLOCAL(tty))
1057                                 tty_hangup(tty);
1058         }
1059         if (brk & 0x01)
1060                 tty_insert_flip_char(&dlci->port, 0, TTY_BREAK);
1061         dlci->modem_rx = mlines;
1062 }
1063 
1064 /**
1065  *      gsm_control_modem       -       modem status received
1066  *      @gsm: GSM channel
1067  *      @data: data following command
1068  *      @clen: command length
1069  *
1070  *      We have received a modem status control message. This is used by
1071  *      the GSM mux protocol to pass virtual modem line status and optionally
1072  *      to indicate break signals. Unpack it, convert to Linux representation
1073  *      and if need be stuff a break message down the tty.
1074  */
1075 
1076 static void gsm_control_modem(struct gsm_mux *gsm, const u8 *data, int clen)
1077 {
1078         unsigned int addr = 0;
1079         unsigned int modem = 0;
1080         unsigned int brk = 0;
1081         struct gsm_dlci *dlci;
1082         int len = clen;
1083         const u8 *dp = data;
1084         struct tty_struct *tty;
1085 
1086         while (gsm_read_ea(&addr, *dp++) == 0) {
1087                 len--;
1088                 if (len == 0)
1089                         return;
1090         }
1091         /* Must be at least one byte following the EA */
1092         len--;
1093         if (len <= 0)
1094                 return;
1095 
1096         addr >>= 1;
1097         /* Closed port, or invalid ? */
1098         if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1099                 return;
1100         dlci = gsm->dlci[addr];
1101 
1102         while (gsm_read_ea(&modem, *dp++) == 0) {
1103                 len--;
1104                 if (len == 0)
1105                         return;
1106         }
1107         len--;
1108         if (len > 0) {
1109                 while (gsm_read_ea(&brk, *dp++) == 0) {
1110                         len--;
1111                         if (len == 0)
1112                                 return;
1113                 }
1114                 modem <<= 7;
1115                 modem |= (brk & 0x7f);
1116         }
1117         tty = tty_port_tty_get(&dlci->port);
1118         gsm_process_modem(tty, dlci, modem, clen);
1119         if (tty) {
1120                 tty_wakeup(tty);
1121                 tty_kref_put(tty);
1122         }
1123         gsm_control_reply(gsm, CMD_MSC, data, clen);
1124 }
1125 
1126 /**
1127  *      gsm_control_rls         -       remote line status
1128  *      @gsm: GSM channel
1129  *      @data: data bytes
1130  *      @clen: data length
1131  *
1132  *      The modem sends us a two byte message on the control channel whenever
1133  *      it wishes to send us an error state from the virtual link. Stuff
1134  *      this into the uplink tty if present
1135  */
1136 
1137 static void gsm_control_rls(struct gsm_mux *gsm, const u8 *data, int clen)
1138 {
1139         struct tty_port *port;
1140         unsigned int addr = 0;
1141         u8 bits;
1142         int len = clen;
1143         const u8 *dp = data;
1144 
1145         while (gsm_read_ea(&addr, *dp++) == 0) {
1146                 len--;
1147                 if (len == 0)
1148                         return;
1149         }
1150         /* Must be at least one byte following ea */
1151         len--;
1152         if (len <= 0)
1153                 return;
1154         addr >>= 1;
1155         /* Closed port, or invalid ? */
1156         if (addr == 0 || addr >= NUM_DLCI || gsm->dlci[addr] == NULL)
1157                 return;
1158         /* No error ? */
1159         bits = *dp;
1160         if ((bits & 1) == 0)
1161                 return;
1162 
1163         port = &gsm->dlci[addr]->port;
1164 
1165         if (bits & 2)
1166                 tty_insert_flip_char(port, 0, TTY_OVERRUN);
1167         if (bits & 4)
1168                 tty_insert_flip_char(port, 0, TTY_PARITY);
1169         if (bits & 8)
1170                 tty_insert_flip_char(port, 0, TTY_FRAME);
1171 
1172         tty_flip_buffer_push(port);
1173 
1174         gsm_control_reply(gsm, CMD_RLS, data, clen);
1175 }
1176 
1177 static void gsm_dlci_begin_close(struct gsm_dlci *dlci);
1178 
1179 /**
1180  *      gsm_control_message     -       DLCI 0 control processing
1181  *      @gsm: our GSM mux
1182  *      @command:  the command EA
1183  *      @data: data beyond the command/length EAs
1184  *      @clen: length
1185  *
1186  *      Input processor for control messages from the other end of the link.
1187  *      Processes the incoming request and queues a response frame or an
1188  *      NSC response if not supported
1189  */
1190 
1191 static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
1192                                                 const u8 *data, int clen)
1193 {
1194         u8 buf[1];
1195         unsigned long flags;
1196 
1197         switch (command) {
1198         case CMD_CLD: {
1199                 struct gsm_dlci *dlci = gsm->dlci[0];
1200                 /* Modem wishes to close down */
1201                 if (dlci) {
1202                         dlci->dead = 1;
1203                         gsm->dead = 1;
1204                         gsm_dlci_begin_close(dlci);
1205                 }
1206                 }
1207                 break;
1208         case CMD_TEST:
1209                 /* Modem wishes to test, reply with the data */
1210                 gsm_control_reply(gsm, CMD_TEST, data, clen);
1211                 break;
1212         case CMD_FCON:
1213                 /* Modem can accept data again */
1214                 gsm->constipated = 0;
1215                 gsm_control_reply(gsm, CMD_FCON, NULL, 0);
1216                 /* Kick the link in case it is idling */
1217                 spin_lock_irqsave(&gsm->tx_lock, flags);
1218                 gsm_data_kick(gsm);
1219                 spin_unlock_irqrestore(&gsm->tx_lock, flags);
1220                 break;
1221         case CMD_FCOFF:
1222                 /* Modem wants us to STFU */
1223                 gsm->constipated = 1;
1224                 gsm_control_reply(gsm, CMD_FCOFF, NULL, 0);
1225                 break;
1226         case CMD_MSC:
1227                 /* Out of band modem line change indicator for a DLCI */
1228                 gsm_control_modem(gsm, data, clen);
1229                 break;
1230         case CMD_RLS:
1231                 /* Out of band error reception for a DLCI */
1232                 gsm_control_rls(gsm, data, clen);
1233                 break;
1234         case CMD_PSC:
1235                 /* Modem wishes to enter power saving state */
1236                 gsm_control_reply(gsm, CMD_PSC, NULL, 0);
1237                 break;
1238                 /* Optional unsupported commands */
1239         case CMD_PN:    /* Parameter negotiation */
1240         case CMD_RPN:   /* Remote port negotiation */
1241         case CMD_SNC:   /* Service negotiation command */
1242         default:
1243                 /* Reply to bad commands with an NSC */
1244                 buf[0] = command;
1245                 gsm_control_reply(gsm, CMD_NSC, buf, 1);
1246                 break;
1247         }
1248 }
1249 
1250 /**
1251  *      gsm_control_response    -       process a response to our control
1252  *      @gsm: our GSM mux
1253  *      @command: the command (response) EA
1254  *      @data: data beyond the command/length EA
1255  *      @clen: length
1256  *
1257  *      Process a response to an outstanding command. We only allow a single
1258  *      control message in flight so this is fairly easy. All the clean up
1259  *      is done by the caller, we just update the fields, flag it as done
1260  *      and return
1261  */
1262 
1263 static void gsm_control_response(struct gsm_mux *gsm, unsigned int command,
1264                                                 const u8 *data, int clen)
1265 {
1266         struct gsm_control *ctrl;
1267         unsigned long flags;
1268 
1269         spin_lock_irqsave(&gsm->control_lock, flags);
1270 
1271         ctrl = gsm->pending_cmd;
1272         /* Does the reply match our command */
1273         command |= 1;
1274         if (ctrl != NULL && (command == ctrl->cmd || command == CMD_NSC)) {
1275                 /* Our command was replied to, kill the retry timer */
1276                 del_timer(&gsm->t2_timer);
1277                 gsm->pending_cmd = NULL;
1278                 /* Rejected by the other end */
1279                 if (command == CMD_NSC)
1280                         ctrl->error = -EOPNOTSUPP;
1281                 ctrl->done = 1;
1282                 wake_up(&gsm->event);
1283         }
1284         spin_unlock_irqrestore(&gsm->control_lock, flags);
1285 }
1286 
1287 /**
1288  *      gsm_control_transmit    -       send control packet
1289  *      @gsm: gsm mux
1290  *      @ctrl: frame to send
1291  *
1292  *      Send out a pending control command (called under control lock)
1293  */
1294 
1295 static void gsm_control_transmit(struct gsm_mux *gsm, struct gsm_control *ctrl)
1296 {
1297         struct gsm_msg *msg = gsm_data_alloc(gsm, 0, ctrl->len + 1, gsm->ftype);
1298         if (msg == NULL)
1299                 return;
1300         msg->data[0] = (ctrl->cmd << 1) | 2 | EA;       /* command */
1301         memcpy(msg->data + 1, ctrl->data, ctrl->len);
1302         gsm_data_queue(gsm->dlci[0], msg);
1303 }
1304 
1305 /**
1306  *      gsm_control_retransmit  -       retransmit a control frame
1307  *      @data: pointer to our gsm object
1308  *
1309  *      Called off the T2 timer expiry in order to retransmit control frames
1310  *      that have been lost in the system somewhere. The control_lock protects
1311  *      us from colliding with another sender or a receive completion event.
1312  *      In that situation the timer may still occur in a small window but
1313  *      gsm->pending_cmd will be NULL and we just let the timer expire.
1314  */
1315 
1316 static void gsm_control_retransmit(struct timer_list *t)
1317 {
1318         struct gsm_mux *gsm = from_timer(gsm, t, t2_timer);
1319         struct gsm_control *ctrl;
1320         unsigned long flags;
1321         spin_lock_irqsave(&gsm->control_lock, flags);
1322         ctrl = gsm->pending_cmd;
1323         if (ctrl) {
1324                 gsm->cretries--;
1325                 if (gsm->cretries == 0) {
1326                         gsm->pending_cmd = NULL;
1327                         ctrl->error = -ETIMEDOUT;
1328                         ctrl->done = 1;
1329                         spin_unlock_irqrestore(&gsm->control_lock, flags);
1330                         wake_up(&gsm->event);
1331                         return;
1332                 }
1333                 gsm_control_transmit(gsm, ctrl);
1334                 mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
1335         }
1336         spin_unlock_irqrestore(&gsm->control_lock, flags);
1337 }
1338 
1339 /**
1340  *      gsm_control_send        -       send a control frame on DLCI 0
1341  *      @gsm: the GSM channel
1342  *      @command: command  to send including CR bit
1343  *      @data: bytes of data (must be kmalloced)
1344  *      @len: length of the block to send
1345  *
1346  *      Queue and dispatch a control command. Only one command can be
1347  *      active at a time. In theory more can be outstanding but the matching
1348  *      gets really complicated so for now stick to one outstanding.
1349  */
1350 
1351 static struct gsm_control *gsm_control_send(struct gsm_mux *gsm,
1352                 unsigned int command, u8 *data, int clen)
1353 {
1354         struct gsm_control *ctrl = kzalloc(sizeof(struct gsm_control),
1355                                                 GFP_KERNEL);
1356         unsigned long flags;
1357         if (ctrl == NULL)
1358                 return NULL;
1359 retry:
1360         wait_event(gsm->event, gsm->pending_cmd == NULL);
1361         spin_lock_irqsave(&gsm->control_lock, flags);
1362         if (gsm->pending_cmd != NULL) {
1363                 spin_unlock_irqrestore(&gsm->control_lock, flags);
1364                 goto retry;
1365         }
1366         ctrl->cmd = command;
1367         ctrl->data = data;
1368         ctrl->len = clen;
1369         gsm->pending_cmd = ctrl;
1370 
1371         /* If DLCI0 is in ADM mode skip retries, it won't respond */
1372         if (gsm->dlci[0]->mode == DLCI_MODE_ADM)
1373                 gsm->cretries = 1;
1374         else
1375                 gsm->cretries = gsm->n2;
1376 
1377         mod_timer(&gsm->t2_timer, jiffies + gsm->t2 * HZ / 100);
1378         gsm_control_transmit(gsm, ctrl);
1379         spin_unlock_irqrestore(&gsm->control_lock, flags);
1380         return ctrl;
1381 }
1382 
1383 /**
1384  *      gsm_control_wait        -       wait for a control to finish
1385  *      @gsm: GSM mux
1386  *      @control: control we are waiting on
1387  *
1388  *      Waits for the control to complete or time out. Frees any used
1389  *      resources and returns 0 for success, or an error if the remote
1390  *      rejected or ignored the request.
1391  */
1392 
1393 static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control)
1394 {
1395         int err;
1396         wait_event(gsm->event, control->done == 1);
1397         err = control->error;
1398         kfree(control);
1399         return err;
1400 }
1401 
1402 
1403 /*
1404  *      DLCI level handling: Needs krefs
1405  */
1406 
1407 /*
1408  *      State transitions and timers
1409  */
1410 
1411 /**
1412  *      gsm_dlci_close          -       a DLCI has closed
1413  *      @dlci: DLCI that closed
1414  *
1415  *      Perform processing when moving a DLCI into closed state. If there
1416  *      is an attached tty this is hung up
1417  */
1418 
1419 static void gsm_dlci_close(struct gsm_dlci *dlci)
1420 {
1421         del_timer(&dlci->t1);
1422         if (debug & 8)
1423                 pr_debug("DLCI %d goes closed.\n", dlci->addr);
1424         dlci->state = DLCI_CLOSED;
1425         if (dlci->addr != 0) {
1426                 tty_port_tty_hangup(&dlci->port, false);
1427                 kfifo_reset(dlci->fifo);
1428         } else
1429                 dlci->gsm->dead = 1;
1430         wake_up(&dlci->gsm->event);
1431         /* A DLCI 0 close is a MUX termination so we need to kick that
1432            back to userspace somehow */
1433 }
1434 
1435 /**
1436  *      gsm_dlci_open           -       a DLCI has opened
1437  *      @dlci: DLCI that opened
1438  *
1439  *      Perform processing when moving a DLCI into open state.
1440  */
1441 
1442 static void gsm_dlci_open(struct gsm_dlci *dlci)
1443 {
1444         /* Note that SABM UA .. SABM UA first UA lost can mean that we go
1445            open -> open */
1446         del_timer(&dlci->t1);
1447         /* This will let a tty open continue */
1448         dlci->state = DLCI_OPEN;
1449         if (debug & 8)
1450                 pr_debug("DLCI %d goes open.\n", dlci->addr);
1451         wake_up(&dlci->gsm->event);
1452 }
1453 
1454 /**
1455  *      gsm_dlci_t1             -       T1 timer expiry
1456  *      @dlci: DLCI that opened
1457  *
1458  *      The T1 timer handles retransmits of control frames (essentially of
1459  *      SABM and DISC). We resend the command until the retry count runs out
1460  *      in which case an opening port goes back to closed and a closing port
1461  *      is simply put into closed state (any further frames from the other
1462  *      end will get a DM response)
1463  *
1464  *      Some control dlci can stay in ADM mode with other dlci working just
1465  *      fine. In that case we can just keep the control dlci open after the
1466  *      DLCI_OPENING retries time out.
1467  */
1468 
1469 static void gsm_dlci_t1(struct timer_list *t)
1470 {
1471         struct gsm_dlci *dlci = from_timer(dlci, t, t1);
1472         struct gsm_mux *gsm = dlci->gsm;
1473 
1474         switch (dlci->state) {
1475         case DLCI_OPENING:
1476                 dlci->retries--;
1477                 if (dlci->retries) {
1478                         gsm_command(dlci->gsm, dlci->addr, SABM|PF);
1479                         mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1480                 } else if (!dlci->addr && gsm->control == (DM | PF)) {
1481                         if (debug & 8)
1482                                 pr_info("DLCI %d opening in ADM mode.\n",
1483                                         dlci->addr);
1484                         dlci->mode = DLCI_MODE_ADM;
1485                         gsm_dlci_open(dlci);
1486                 } else {
1487                         gsm_dlci_close(dlci);
1488                 }
1489 
1490                 break;
1491         case DLCI_CLOSING:
1492                 dlci->retries--;
1493                 if (dlci->retries) {
1494                         gsm_command(dlci->gsm, dlci->addr, DISC|PF);
1495                         mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1496                 } else
1497                         gsm_dlci_close(dlci);
1498                 break;
1499         }
1500 }
1501 
1502 /**
1503  *      gsm_dlci_begin_open     -       start channel open procedure
1504  *      @dlci: DLCI to open
1505  *
1506  *      Commence opening a DLCI from the Linux side. We issue SABM messages
1507  *      to the modem which should then reply with a UA or ADM, at which point
1508  *      we will move into open state. Opening is done asynchronously with retry
1509  *      running off timers and the responses.
1510  */
1511 
1512 static void gsm_dlci_begin_open(struct gsm_dlci *dlci)
1513 {
1514         struct gsm_mux *gsm = dlci->gsm;
1515         if (dlci->state == DLCI_OPEN || dlci->state == DLCI_OPENING)
1516                 return;
1517         dlci->retries = gsm->n2;
1518         dlci->state = DLCI_OPENING;
1519         gsm_command(dlci->gsm, dlci->addr, SABM|PF);
1520         mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1521 }
1522 
1523 /**
1524  *      gsm_dlci_begin_close    -       start channel open procedure
1525  *      @dlci: DLCI to open
1526  *
1527  *      Commence closing a DLCI from the Linux side. We issue DISC messages
1528  *      to the modem which should then reply with a UA, at which point we
1529  *      will move into closed state. Closing is done asynchronously with retry
1530  *      off timers. We may also receive a DM reply from the other end which
1531  *      indicates the channel was already closed.
1532  */
1533 
1534 static void gsm_dlci_begin_close(struct gsm_dlci *dlci)
1535 {
1536         struct gsm_mux *gsm = dlci->gsm;
1537         if (dlci->state == DLCI_CLOSED || dlci->state == DLCI_CLOSING)
1538                 return;
1539         dlci->retries = gsm->n2;
1540         dlci->state = DLCI_CLOSING;
1541         gsm_command(dlci->gsm, dlci->addr, DISC|PF);
1542         mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
1543 }
1544 
1545 /**
1546  *      gsm_dlci_data           -       data arrived
1547  *      @dlci: channel
1548  *      @data: block of bytes received
1549  *      @len: length of received block
1550  *
1551  *      A UI or UIH frame has arrived which contains data for a channel
1552  *      other than the control channel. If the relevant virtual tty is
1553  *      open we shovel the bits down it, if not we drop them.
1554  */
1555 
1556 static void gsm_dlci_data(struct gsm_dlci *dlci, const u8 *data, int clen)
1557 {
1558         /* krefs .. */
1559         struct tty_port *port = &dlci->port;
1560         struct tty_struct *tty;
1561         unsigned int modem = 0;
1562         int len = clen;
1563 
1564         if (debug & 16)
1565                 pr_debug("%d bytes for tty\n", len);
1566         switch (dlci->adaption)  {
1567         /* Unsupported types */
1568         case 4:         /* Packetised interruptible data */
1569                 break;
1570         case 3:         /* Packetised uininterruptible voice/data */
1571                 break;
1572         case 2:         /* Asynchronous serial with line state in each frame */
1573                 while (gsm_read_ea(&modem, *data++) == 0) {
1574                         len--;
1575                         if (len == 0)
1576                                 return;
1577                 }
1578                 tty = tty_port_tty_get(port);
1579                 if (tty) {
1580                         gsm_process_modem(tty, dlci, modem, clen);
1581                         tty_kref_put(tty);
1582                 }
1583                 /* Fall through */
1584         case 1:         /* Line state will go via DLCI 0 controls only */
1585         default:
1586                 tty_insert_flip_string(port, data, len);
1587                 tty_flip_buffer_push(port);
1588         }
1589 }
1590 
1591 /**
1592  *      gsm_dlci_control        -       data arrived on control channel
1593  *      @dlci: channel
1594  *      @data: block of bytes received
1595  *      @len: length of received block
1596  *
1597  *      A UI or UIH frame has arrived which contains data for DLCI 0 the
1598  *      control channel. This should contain a command EA followed by
1599  *      control data bytes. The command EA contains a command/response bit
1600  *      and we divide up the work accordingly.
1601  */
1602 
1603 static void gsm_dlci_command(struct gsm_dlci *dlci, const u8 *data, int len)
1604 {
1605         /* See what command is involved */
1606         unsigned int command = 0;
1607         while (len-- > 0) {
1608                 if (gsm_read_ea(&command, *data++) == 1) {
1609                         int clen = *data++;
1610                         len--;
1611                         /* FIXME: this is properly an EA */
1612                         clen >>= 1;
1613                         /* Malformed command ? */
1614                         if (clen > len)
1615                                 return;
1616                         if (command & 1)
1617                                 gsm_control_message(dlci->gsm, command,
1618                                                                 data, clen);
1619                         else
1620                                 gsm_control_response(dlci->gsm, command,
1621                                                                 data, clen);
1622                         return;
1623                 }
1624         }
1625 }
1626 
1627 /*
1628  *      Allocate/Free DLCI channels
1629  */
1630 
1631 /**
1632  *      gsm_dlci_alloc          -       allocate a DLCI
1633  *      @gsm: GSM mux
1634  *      @addr: address of the DLCI
1635  *
1636  *      Allocate and install a new DLCI object into the GSM mux.
1637  *
1638  *      FIXME: review locking races
1639  */
1640 
1641 static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr)
1642 {
1643         struct gsm_dlci *dlci = kzalloc(sizeof(struct gsm_dlci), GFP_ATOMIC);
1644         if (dlci == NULL)
1645                 return NULL;
1646         spin_lock_init(&dlci->lock);
1647         mutex_init(&dlci->mutex);
1648         dlci->fifo = &dlci->_fifo;
1649         if (kfifo_alloc(&dlci->_fifo, 4096, GFP_KERNEL) < 0) {
1650                 kfree(dlci);
1651                 return NULL;
1652         }
1653 
1654         skb_queue_head_init(&dlci->skb_list);
1655         timer_setup(&dlci->t1, gsm_dlci_t1, 0);
1656         tty_port_init(&dlci->port);
1657         dlci->port.ops = &gsm_port_ops;
1658         dlci->gsm = gsm;
1659         dlci->addr = addr;
1660         dlci->adaption = gsm->adaption;
1661         dlci->state = DLCI_CLOSED;
1662         if (addr)
1663                 dlci->data = gsm_dlci_data;
1664         else
1665                 dlci->data = gsm_dlci_command;
1666         gsm->dlci[addr] = dlci;
1667         return dlci;
1668 }
1669 
1670 /**
1671  *      gsm_dlci_free           -       free DLCI
1672  *      @dlci: DLCI to free
1673  *
1674  *      Free up a DLCI.
1675  *
1676  *      Can sleep.
1677  */
1678 static void gsm_dlci_free(struct tty_port *port)
1679 {
1680         struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
1681 
1682         del_timer_sync(&dlci->t1);
1683         dlci->gsm->dlci[dlci->addr] = NULL;
1684         kfifo_free(dlci->fifo);
1685         while ((dlci->skb = skb_dequeue(&dlci->skb_list)))
1686                 dev_kfree_skb(dlci->skb);
1687         kfree(dlci);
1688 }
1689 
1690 static inline void dlci_get(struct gsm_dlci *dlci)
1691 {
1692         tty_port_get(&dlci->port);
1693 }
1694 
1695 static inline void dlci_put(struct gsm_dlci *dlci)
1696 {
1697         tty_port_put(&dlci->port);
1698 }
1699 
1700 static void gsm_destroy_network(struct gsm_dlci *dlci);
1701 
1702 /**
1703  *      gsm_dlci_release                -       release DLCI
1704  *      @dlci: DLCI to destroy
1705  *
1706  *      Release a DLCI. Actual free is deferred until either
1707  *      mux is closed or tty is closed - whichever is last.
1708  *
1709  *      Can sleep.
1710  */
1711 static void gsm_dlci_release(struct gsm_dlci *dlci)
1712 {
1713         struct tty_struct *tty = tty_port_tty_get(&dlci->port);
1714         if (tty) {
1715                 mutex_lock(&dlci->mutex);
1716                 gsm_destroy_network(dlci);
1717                 mutex_unlock(&dlci->mutex);
1718 
1719                 tty_hangup(tty);
1720 
1721                 tty_port_tty_set(&dlci->port, NULL);
1722                 tty_kref_put(tty);
1723         }
1724         dlci->state = DLCI_CLOSED;
1725         dlci_put(dlci);
1726 }
1727 
1728 /*
1729  *      LAPBish link layer logic
1730  */
1731 
1732 /**
1733  *      gsm_queue               -       a GSM frame is ready to process
1734  *      @gsm: pointer to our gsm mux
1735  *
1736  *      At this point in time a frame has arrived and been demangled from
1737  *      the line encoding. All the differences between the encodings have
1738  *      been handled below us and the frame is unpacked into the structures.
1739  *      The fcs holds the header FCS but any data FCS must be added here.
1740  */
1741 
1742 static void gsm_queue(struct gsm_mux *gsm)
1743 {
1744         struct gsm_dlci *dlci;
1745         u8 cr;
1746         int address;
1747         /* We have to sneak a look at the packet body to do the FCS.
1748            A somewhat layering violation in the spec */
1749 
1750         if ((gsm->control & ~PF) == UI)
1751                 gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf, gsm->len);
1752         if (gsm->encoding == 0) {
1753                 /* WARNING: gsm->received_fcs is used for
1754                 gsm->encoding = 0 only.
1755                 In this case it contain the last piece of data
1756                 required to generate final CRC */
1757                 gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->received_fcs);
1758         }
1759         if (gsm->fcs != GOOD_FCS) {
1760                 gsm->bad_fcs++;
1761                 if (debug & 4)
1762                         pr_debug("BAD FCS %02x\n", gsm->fcs);
1763                 return;
1764         }
1765         address = gsm->address >> 1;
1766         if (address >= NUM_DLCI)
1767                 goto invalid;
1768 
1769         cr = gsm->address & 1;          /* C/R bit */
1770 
1771         gsm_print_packet("<--", address, cr, gsm->control, gsm->buf, gsm->len);
1772 
1773         cr ^= 1 - gsm->initiator;       /* Flip so 1 always means command */
1774         dlci = gsm->dlci[address];
1775 
1776         switch (gsm->control) {
1777         case SABM|PF:
1778                 if (cr == 0)
1779                         goto invalid;
1780                 if (dlci == NULL)
1781                         dlci = gsm_dlci_alloc(gsm, address);
1782                 if (dlci == NULL)
1783                         return;
1784                 if (dlci->dead)
1785                         gsm_response(gsm, address, DM);
1786                 else {
1787                         gsm_response(gsm, address, UA);
1788                         gsm_dlci_open(dlci);
1789                 }
1790                 break;
1791         case DISC|PF:
1792                 if (cr == 0)
1793                         goto invalid;
1794                 if (dlci == NULL || dlci->state == DLCI_CLOSED) {
1795                         gsm_response(gsm, address, DM);
1796                         return;
1797                 }
1798                 /* Real close complete */
1799                 gsm_response(gsm, address, UA);
1800                 gsm_dlci_close(dlci);
1801                 break;
1802         case UA:
1803         case UA|PF:
1804                 if (cr == 0 || dlci == NULL)
1805                         break;
1806                 switch (dlci->state) {
1807                 case DLCI_CLOSING:
1808                         gsm_dlci_close(dlci);
1809                         break;
1810                 case DLCI_OPENING:
1811                         gsm_dlci_open(dlci);
1812                         break;
1813                 }
1814                 break;
1815         case DM:        /* DM can be valid unsolicited */
1816         case DM|PF:
1817                 if (cr)
1818                         goto invalid;
1819                 if (dlci == NULL)
1820                         return;
1821                 gsm_dlci_close(dlci);
1822                 break;
1823         case UI:
1824         case UI|PF:
1825         case UIH:
1826         case UIH|PF:
1827 #if 0
1828                 if (cr)
1829                         goto invalid;
1830 #endif
1831                 if (dlci == NULL || dlci->state != DLCI_OPEN) {
1832                         gsm_command(gsm, address, DM|PF);
1833                         return;
1834                 }
1835                 dlci->data(dlci, gsm->buf, gsm->len);
1836                 break;
1837         default:
1838                 goto invalid;
1839         }
1840         return;
1841 invalid:
1842         gsm->malformed++;
1843         return;
1844 }
1845 
1846 
1847 /**
1848  *      gsm0_receive    -       perform processing for non-transparency
1849  *      @gsm: gsm data for this ldisc instance
1850  *      @c: character
1851  *
1852  *      Receive bytes in gsm mode 0
1853  */
1854 
1855 static void gsm0_receive(struct gsm_mux *gsm, unsigned char c)
1856 {
1857         unsigned int len;
1858 
1859         switch (gsm->state) {
1860         case GSM_SEARCH:        /* SOF marker */
1861                 if (c == GSM0_SOF) {
1862                         gsm->state = GSM_ADDRESS;
1863                         gsm->address = 0;
1864                         gsm->len = 0;
1865                         gsm->fcs = INIT_FCS;
1866                 }
1867                 break;
1868         case GSM_ADDRESS:       /* Address EA */
1869                 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1870                 if (gsm_read_ea(&gsm->address, c))
1871                         gsm->state = GSM_CONTROL;
1872                 break;
1873         case GSM_CONTROL:       /* Control Byte */
1874                 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1875                 gsm->control = c;
1876                 gsm->state = GSM_LEN0;
1877                 break;
1878         case GSM_LEN0:          /* Length EA */
1879                 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1880                 if (gsm_read_ea(&gsm->len, c)) {
1881                         if (gsm->len > gsm->mru) {
1882                                 gsm->bad_size++;
1883                                 gsm->state = GSM_SEARCH;
1884                                 break;
1885                         }
1886                         gsm->count = 0;
1887                         if (!gsm->len)
1888                                 gsm->state = GSM_FCS;
1889                         else
1890                                 gsm->state = GSM_DATA;
1891                         break;
1892                 }
1893                 gsm->state = GSM_LEN1;
1894                 break;
1895         case GSM_LEN1:
1896                 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1897                 len = c;
1898                 gsm->len |= len << 7;
1899                 if (gsm->len > gsm->mru) {
1900                         gsm->bad_size++;
1901                         gsm->state = GSM_SEARCH;
1902                         break;
1903                 }
1904                 gsm->count = 0;
1905                 if (!gsm->len)
1906                         gsm->state = GSM_FCS;
1907                 else
1908                         gsm->state = GSM_DATA;
1909                 break;
1910         case GSM_DATA:          /* Data */
1911                 gsm->buf[gsm->count++] = c;
1912                 if (gsm->count == gsm->len)
1913                         gsm->state = GSM_FCS;
1914                 break;
1915         case GSM_FCS:           /* FCS follows the packet */
1916                 gsm->received_fcs = c;
1917                 gsm_queue(gsm);
1918                 gsm->state = GSM_SSOF;
1919                 break;
1920         case GSM_SSOF:
1921                 if (c == GSM0_SOF) {
1922                         gsm->state = GSM_SEARCH;
1923                         break;
1924                 }
1925                 break;
1926         }
1927 }
1928 
1929 /**
1930  *      gsm1_receive    -       perform processing for non-transparency
1931  *      @gsm: gsm data for this ldisc instance
1932  *      @c: character
1933  *
1934  *      Receive bytes in mode 1 (Advanced option)
1935  */
1936 
1937 static void gsm1_receive(struct gsm_mux *gsm, unsigned char c)
1938 {
1939         if (c == GSM1_SOF) {
1940                 /* EOF is only valid in frame if we have got to the data state
1941                    and received at least one byte (the FCS) */
1942                 if (gsm->state == GSM_DATA && gsm->count) {
1943                         /* Extract the FCS */
1944                         gsm->count--;
1945                         gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->buf[gsm->count]);
1946                         gsm->len = gsm->count;
1947                         gsm_queue(gsm);
1948                         gsm->state  = GSM_START;
1949                         return;
1950                 }
1951                 /* Any partial frame was a runt so go back to start */
1952                 if (gsm->state != GSM_START) {
1953                         gsm->malformed++;
1954                         gsm->state = GSM_START;
1955                 }
1956                 /* A SOF in GSM_START means we are still reading idling or
1957                    framing bytes */
1958                 return;
1959         }
1960 
1961         if (c == GSM1_ESCAPE) {
1962                 gsm->escape = 1;
1963                 return;
1964         }
1965 
1966         /* Only an unescaped SOF gets us out of GSM search */
1967         if (gsm->state == GSM_SEARCH)
1968                 return;
1969 
1970         if (gsm->escape) {
1971                 c ^= GSM1_ESCAPE_BITS;
1972                 gsm->escape = 0;
1973         }
1974         switch (gsm->state) {
1975         case GSM_START:         /* First byte after SOF */
1976                 gsm->address = 0;
1977                 gsm->state = GSM_ADDRESS;
1978                 gsm->fcs = INIT_FCS;
1979                 /* Fall through */
1980         case GSM_ADDRESS:       /* Address continuation */
1981                 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1982                 if (gsm_read_ea(&gsm->address, c))
1983                         gsm->state = GSM_CONTROL;
1984                 break;
1985         case GSM_CONTROL:       /* Control Byte */
1986                 gsm->fcs = gsm_fcs_add(gsm->fcs, c);
1987                 gsm->control = c;
1988                 gsm->count = 0;
1989                 gsm->state = GSM_DATA;
1990                 break;
1991         case GSM_DATA:          /* Data */
1992                 if (gsm->count > gsm->mru) {    /* Allow one for the FCS */
1993                         gsm->state = GSM_OVERRUN;
1994                         gsm->bad_size++;
1995                 } else
1996                         gsm->buf[gsm->count++] = c;
1997                 break;
1998         case GSM_OVERRUN:       /* Over-long - eg a dropped SOF */
1999                 break;
2000         }
2001 }
2002 
2003 /**
2004  *      gsm_error               -       handle tty error
2005  *      @gsm: ldisc data
2006  *      @data: byte received (may be invalid)
2007  *      @flag: error received
2008  *
2009  *      Handle an error in the receipt of data for a frame. Currently we just
2010  *      go back to hunting for a SOF.
2011  *
2012  *      FIXME: better diagnostics ?
2013  */
2014 
2015 static void gsm_error(struct gsm_mux *gsm,
2016                                 unsigned char data, unsigned char flag)
2017 {
2018         gsm->state = GSM_SEARCH;
2019         gsm->io_error++;
2020 }
2021 
2022 static int gsm_disconnect(struct gsm_mux *gsm)
2023 {
2024         struct gsm_dlci *dlci = gsm->dlci[0];
2025         struct gsm_control *gc;
2026 
2027         if (!dlci)
2028                 return 0;
2029 
2030         /* In theory disconnecting DLCI 0 is sufficient but for some
2031            modems this is apparently not the case. */
2032         gc = gsm_control_send(gsm, CMD_CLD, NULL, 0);
2033         if (gc)
2034                 gsm_control_wait(gsm, gc);
2035 
2036         del_timer_sync(&gsm->t2_timer);
2037         /* Now we are sure T2 has stopped */
2038 
2039         gsm_dlci_begin_close(dlci);
2040         wait_event_interruptible(gsm->event,
2041                                 dlci->state == DLCI_CLOSED);
2042 
2043         if (signal_pending(current))
2044                 return -EINTR;
2045 
2046         return 0;
2047 }
2048 
2049 /**
2050  *      gsm_cleanup_mux         -       generic GSM protocol cleanup
2051  *      @gsm: our mux
2052  *
2053  *      Clean up the bits of the mux which are the same for all framing
2054  *      protocols. Remove the mux from the mux table, stop all the timers
2055  *      and then shut down each device hanging up the channels as we go.
2056  */
2057 
2058 static void gsm_cleanup_mux(struct gsm_mux *gsm)
2059 {
2060         int i;
2061         struct gsm_dlci *dlci = gsm->dlci[0];
2062         struct gsm_msg *txq, *ntxq;
2063 
2064         gsm->dead = 1;
2065 
2066         spin_lock(&gsm_mux_lock);
2067         for (i = 0; i < MAX_MUX; i++) {
2068                 if (gsm_mux[i] == gsm) {
2069                         gsm_mux[i] = NULL;
2070                         break;
2071                 }
2072         }
2073         spin_unlock(&gsm_mux_lock);
2074         /* open failed before registering => nothing to do */
2075         if (i == MAX_MUX)
2076                 return;
2077 
2078         del_timer_sync(&gsm->t2_timer);
2079         /* Now we are sure T2 has stopped */
2080         if (dlci)
2081                 dlci->dead = 1;
2082 
2083         /* Free up any link layer users */
2084         mutex_lock(&gsm->mutex);
2085         for (i = 0; i < NUM_DLCI; i++)
2086                 if (gsm->dlci[i])
2087                         gsm_dlci_release(gsm->dlci[i]);
2088         mutex_unlock(&gsm->mutex);
2089         /* Now wipe the queues */
2090         list_for_each_entry_safe(txq, ntxq, &gsm->tx_list, list)
2091                 kfree(txq);
2092         INIT_LIST_HEAD(&gsm->tx_list);
2093 }
2094 
2095 /**
2096  *      gsm_activate_mux        -       generic GSM setup
2097  *      @gsm: our mux
2098  *
2099  *      Set up the bits of the mux which are the same for all framing
2100  *      protocols. Add the mux to the mux table so it can be opened and
2101  *      finally kick off connecting to DLCI 0 on the modem.
2102  */
2103 
2104 static int gsm_activate_mux(struct gsm_mux *gsm)
2105 {
2106         struct gsm_dlci *dlci;
2107         int i = 0;
2108 
2109         timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
2110         init_waitqueue_head(&gsm->event);
2111         spin_lock_init(&gsm->control_lock);
2112         spin_lock_init(&gsm->tx_lock);
2113 
2114         if (gsm->encoding == 0)
2115                 gsm->receive = gsm0_receive;
2116         else
2117                 gsm->receive = gsm1_receive;
2118         gsm->error = gsm_error;
2119 
2120         spin_lock(&gsm_mux_lock);
2121         for (i = 0; i < MAX_MUX; i++) {
2122                 if (gsm_mux[i] == NULL) {
2123                         gsm->num = i;
2124                         gsm_mux[i] = gsm;
2125                         break;
2126                 }
2127         }
2128         spin_unlock(&gsm_mux_lock);
2129         if (i == MAX_MUX)
2130                 return -EBUSY;
2131 
2132         dlci = gsm_dlci_alloc(gsm, 0);
2133         if (dlci == NULL)
2134                 return -ENOMEM;
2135         gsm->dead = 0;          /* Tty opens are now permissible */
2136         return 0;
2137 }
2138 
2139 /**
2140  *      gsm_free_mux            -       free up a mux
2141  *      @mux: mux to free
2142  *
2143  *      Dispose of allocated resources for a dead mux
2144  */
2145 static void gsm_free_mux(struct gsm_mux *gsm)
2146 {
2147         kfree(gsm->txframe);
2148         kfree(gsm->buf);
2149         kfree(gsm);
2150 }
2151 
2152 /**
2153  *      gsm_free_muxr           -       free up a mux
2154  *      @mux: mux to free
2155  *
2156  *      Dispose of allocated resources for a dead mux
2157  */
2158 static void gsm_free_muxr(struct kref *ref)
2159 {
2160         struct gsm_mux *gsm = container_of(ref, struct gsm_mux, ref);
2161         gsm_free_mux(gsm);
2162 }
2163 
2164 static inline void mux_get(struct gsm_mux *gsm)
2165 {
2166         kref_get(&gsm->ref);
2167 }
2168 
2169 static inline void mux_put(struct gsm_mux *gsm)
2170 {
2171         kref_put(&gsm->ref, gsm_free_muxr);
2172 }
2173 
2174 static inline unsigned int mux_num_to_base(struct gsm_mux *gsm)
2175 {
2176         return gsm->num * NUM_DLCI;
2177 }
2178 
2179 static inline unsigned int mux_line_to_num(unsigned int line)
2180 {
2181         return line / NUM_DLCI;
2182 }
2183 
2184 /**
2185  *      gsm_alloc_mux           -       allocate a mux
2186  *
2187  *      Creates a new mux ready for activation.
2188  */
2189 
2190 static struct gsm_mux *gsm_alloc_mux(void)
2191 {
2192         struct gsm_mux *gsm = kzalloc(sizeof(struct gsm_mux), GFP_KERNEL);
2193         if (gsm == NULL)
2194                 return NULL;
2195         gsm->buf = kmalloc(MAX_MRU + 1, GFP_KERNEL);
2196         if (gsm->buf == NULL) {
2197                 kfree(gsm);
2198                 return NULL;
2199         }
2200         gsm->txframe = kmalloc(2 * MAX_MRU + 2, GFP_KERNEL);
2201         if (gsm->txframe == NULL) {
2202                 kfree(gsm->buf);
2203                 kfree(gsm);
2204                 return NULL;
2205         }
2206         spin_lock_init(&gsm->lock);
2207         mutex_init(&gsm->mutex);
2208         kref_init(&gsm->ref);
2209         INIT_LIST_HEAD(&gsm->tx_list);
2210 
2211         gsm->t1 = T1;
2212         gsm->t2 = T2;
2213         gsm->n2 = N2;
2214         gsm->ftype = UIH;
2215         gsm->adaption = 1;
2216         gsm->encoding = 1;
2217         gsm->mru = 64;  /* Default to encoding 1 so these should be 64 */
2218         gsm->mtu = 64;
2219         gsm->dead = 1;  /* Avoid early tty opens */
2220 
2221         return gsm;
2222 }
2223 
2224 static void gsm_copy_config_values(struct gsm_mux *gsm,
2225                                    struct gsm_config *c)
2226 {
2227         memset(c, 0, sizeof(*c));
2228         c->adaption = gsm->adaption;
2229         c->encapsulation = gsm->encoding;
2230         c->initiator = gsm->initiator;
2231         c->t1 = gsm->t1;
2232         c->t2 = gsm->t2;
2233         c->t3 = 0;      /* Not supported */
2234         c->n2 = gsm->n2;
2235         if (gsm->ftype == UIH)
2236                 c->i = 1;
2237         else
2238                 c->i = 2;
2239         pr_debug("Ftype %d i %d\n", gsm->ftype, c->i);
2240         c->mru = gsm->mru;
2241         c->mtu = gsm->mtu;
2242         c->k = 0;
2243 }
2244 
2245 static int gsm_config(struct gsm_mux *gsm, struct gsm_config *c)
2246 {
2247         int need_close = 0;
2248         int need_restart = 0;
2249 
2250         /* Stuff we don't support yet - UI or I frame transport, windowing */
2251         if ((c->adaption != 1 && c->adaption != 2) || c->k)
2252                 return -EOPNOTSUPP;
2253         /* Check the MRU/MTU range looks sane */
2254         if (c->mru > MAX_MRU || c->mtu > MAX_MTU || c->mru < 8 || c->mtu < 8)
2255                 return -EINVAL;
2256         if (c->n2 < 3)
2257                 return -EINVAL;
2258         if (c->encapsulation > 1)       /* Basic, advanced, no I */
2259                 return -EINVAL;
2260         if (c->initiator > 1)
2261                 return -EINVAL;
2262         if (c->i == 0 || c->i > 2)      /* UIH and UI only */
2263                 return -EINVAL;
2264         /*
2265          * See what is needed for reconfiguration
2266          */
2267 
2268         /* Timing fields */
2269         if (c->t1 != 0 && c->t1 != gsm->t1)
2270                 need_restart = 1;
2271         if (c->t2 != 0 && c->t2 != gsm->t2)
2272                 need_restart = 1;
2273         if (c->encapsulation != gsm->encoding)
2274                 need_restart = 1;
2275         if (c->adaption != gsm->adaption)
2276                 need_restart = 1;
2277         /* Requires care */
2278         if (c->initiator != gsm->initiator)
2279                 need_close = 1;
2280         if (c->mru != gsm->mru)
2281                 need_restart = 1;
2282         if (c->mtu != gsm->mtu)
2283                 need_restart = 1;
2284 
2285         /*
2286          * Close down what is needed, restart and initiate the new
2287          * configuration
2288          */
2289 
2290         if (need_close || need_restart) {
2291                 int ret;
2292 
2293                 ret = gsm_disconnect(gsm);
2294 
2295                 if (ret)
2296                         return ret;
2297         }
2298         if (need_restart)
2299                 gsm_cleanup_mux(gsm);
2300 
2301         gsm->initiator = c->initiator;
2302         gsm->mru = c->mru;
2303         gsm->mtu = c->mtu;
2304         gsm->encoding = c->encapsulation;
2305         gsm->adaption = c->adaption;
2306         gsm->n2 = c->n2;
2307 
2308         if (c->i == 1)
2309                 gsm->ftype = UIH;
2310         else if (c->i == 2)
2311                 gsm->ftype = UI;
2312 
2313         if (c->t1)
2314                 gsm->t1 = c->t1;
2315         if (c->t2)
2316                 gsm->t2 = c->t2;
2317 
2318         /*
2319          * FIXME: We need to separate activation/deactivation from adding
2320          * and removing from the mux array
2321          */
2322         if (need_restart)
2323                 gsm_activate_mux(gsm);
2324         if (gsm->initiator && need_close)
2325                 gsm_dlci_begin_open(gsm->dlci[0]);
2326         return 0;
2327 }
2328 
2329 /**
2330  *      gsmld_output            -       write to link
2331  *      @gsm: our mux
2332  *      @data: bytes to output
2333  *      @len: size
2334  *
2335  *      Write a block of data from the GSM mux to the data channel. This
2336  *      will eventually be serialized from above but at the moment isn't.
2337  */
2338 
2339 static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len)
2340 {
2341         if (tty_write_room(gsm->tty) < len) {
2342                 set_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
2343                 return -ENOSPC;
2344         }
2345         if (debug & 4)
2346                 print_hex_dump_bytes("gsmld_output: ", DUMP_PREFIX_OFFSET,
2347                                      data, len);
2348         gsm->tty->ops->write(gsm->tty, data, len);
2349         return len;
2350 }
2351 
2352 /**
2353  *      gsmld_attach_gsm        -       mode set up
2354  *      @tty: our tty structure
2355  *      @gsm: our mux
2356  *
2357  *      Set up the MUX for basic mode and commence connecting to the
2358  *      modem. Currently called from the line discipline set up but
2359  *      will need moving to an ioctl path.
2360  */
2361 
2362 static int gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
2363 {
2364         unsigned int base;
2365         int ret, i;
2366 
2367         gsm->tty = tty_kref_get(tty);
2368         gsm->output = gsmld_output;
2369         ret =  gsm_activate_mux(gsm);
2370         if (ret != 0)
2371                 tty_kref_put(gsm->tty);
2372         else {
2373                 /* Don't register device 0 - this is the control channel and not
2374                    a usable tty interface */
2375                 base = mux_num_to_base(gsm); /* Base for this MUX */
2376                 for (i = 1; i < NUM_DLCI; i++)
2377                         tty_register_device(gsm_tty_driver, base + i, NULL);
2378         }
2379         return ret;
2380 }
2381 
2382 
2383 /**
2384  *      gsmld_detach_gsm        -       stop doing 0710 mux
2385  *      @tty: tty attached to the mux
2386  *      @gsm: mux
2387  *
2388  *      Shutdown and then clean up the resources used by the line discipline
2389  */
2390 
2391 static void gsmld_detach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
2392 {
2393         unsigned int base = mux_num_to_base(gsm); /* Base for this MUX */
2394         int i;
2395 
2396         WARN_ON(tty != gsm->tty);
2397         for (i = 1; i < NUM_DLCI; i++)
2398                 tty_unregister_device(gsm_tty_driver, base + i);
2399         gsm_cleanup_mux(gsm);
2400         tty_kref_put(gsm->tty);
2401         gsm->tty = NULL;
2402 }
2403 
2404 static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp,
2405                               char *fp, int count)
2406 {
2407         struct gsm_mux *gsm = tty->disc_data;
2408         const unsigned char *dp;
2409         char *f;
2410         int i;
2411         char flags = TTY_NORMAL;
2412 
2413         if (debug & 4)
2414                 print_hex_dump_bytes("gsmld_receive: ", DUMP_PREFIX_OFFSET,
2415                                      cp, count);
2416 
2417         for (i = count, dp = cp, f = fp; i; i--, dp++) {
2418                 if (f)
2419                         flags = *f++;
2420                 switch (flags) {
2421                 case TTY_NORMAL:
2422                         gsm->receive(gsm, *dp);
2423                         break;
2424                 case TTY_OVERRUN:
2425                 case TTY_BREAK:
2426                 case TTY_PARITY:
2427                 case TTY_FRAME:
2428                         gsm->error(gsm, *dp, flags);
2429                         break;
2430                 default:
2431                         WARN_ONCE(1, "%s: unknown flag %d\n",
2432                                tty_name(tty), flags);
2433                         break;
2434                 }
2435         }
2436         /* FASYNC if needed ? */
2437         /* If clogged call tty_throttle(tty); */
2438 }
2439 
2440 /**
2441  *      gsmld_flush_buffer      -       clean input queue
2442  *      @tty:   terminal device
2443  *
2444  *      Flush the input buffer. Called when the line discipline is
2445  *      being closed, when the tty layer wants the buffer flushed (eg
2446  *      at hangup).
2447  */
2448 
2449 static void gsmld_flush_buffer(struct tty_struct *tty)
2450 {
2451 }
2452 
2453 /**
2454  *      gsmld_close             -       close the ldisc for this tty
2455  *      @tty: device
2456  *
2457  *      Called from the terminal layer when this line discipline is
2458  *      being shut down, either because of a close or becsuse of a
2459  *      discipline change. The function will not be called while other
2460  *      ldisc methods are in progress.
2461  */
2462 
2463 static void gsmld_close(struct tty_struct *tty)
2464 {
2465         struct gsm_mux *gsm = tty->disc_data;
2466 
2467         gsmld_detach_gsm(tty, gsm);
2468 
2469         gsmld_flush_buffer(tty);
2470         /* Do other clean up here */
2471         mux_put(gsm);
2472 }
2473 
2474 /**
2475  *      gsmld_open              -       open an ldisc
2476  *      @tty: terminal to open
2477  *
2478  *      Called when this line discipline is being attached to the
2479  *      terminal device. Can sleep. Called serialized so that no
2480  *      other events will occur in parallel. No further open will occur
2481  *      until a close.
2482  */
2483 
2484 static int gsmld_open(struct tty_struct *tty)
2485 {
2486         struct gsm_mux *gsm;
2487         int ret;
2488 
2489         if (tty->ops->write == NULL)
2490                 return -EINVAL;
2491 
2492         /* Attach our ldisc data */
2493         gsm = gsm_alloc_mux();
2494         if (gsm == NULL)
2495                 return -ENOMEM;
2496 
2497         tty->disc_data = gsm;
2498         tty->receive_room = 65536;
2499 
2500         /* Attach the initial passive connection */
2501         gsm->encoding = 1;
2502 
2503         ret = gsmld_attach_gsm(tty, gsm);
2504         if (ret != 0) {
2505                 gsm_cleanup_mux(gsm);
2506                 mux_put(gsm);
2507         }
2508         return ret;
2509 }
2510 
2511 /**
2512  *      gsmld_write_wakeup      -       asynchronous I/O notifier
2513  *      @tty: tty device
2514  *
2515  *      Required for the ptys, serial driver etc. since processes
2516  *      that attach themselves to the master and rely on ASYNC
2517  *      IO must be woken up
2518  */
2519 
2520 static void gsmld_write_wakeup(struct tty_struct *tty)
2521 {
2522         struct gsm_mux *gsm = tty->disc_data;
2523         unsigned long flags;
2524 
2525         /* Queue poll */
2526         clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2527         spin_lock_irqsave(&gsm->tx_lock, flags);
2528         gsm_data_kick(gsm);
2529         if (gsm->tx_bytes < TX_THRESH_LO) {
2530                 gsm_dlci_data_sweep(gsm);
2531         }
2532         spin_unlock_irqrestore(&gsm->tx_lock, flags);
2533 }
2534 
2535 /**
2536  *      gsmld_read              -       read function for tty
2537  *      @tty: tty device
2538  *      @file: file object
2539  *      @buf: userspace buffer pointer
2540  *      @nr: size of I/O
2541  *
2542  *      Perform reads for the line discipline. We are guaranteed that the
2543  *      line discipline will not be closed under us but we may get multiple
2544  *      parallel readers and must handle this ourselves. We may also get
2545  *      a hangup. Always called in user context, may sleep.
2546  *
2547  *      This code must be sure never to sleep through a hangup.
2548  */
2549 
2550 static ssize_t gsmld_read(struct tty_struct *tty, struct file *file,
2551                          unsigned char __user *buf, size_t nr)
2552 {
2553         return -EOPNOTSUPP;
2554 }
2555 
2556 /**
2557  *      gsmld_write             -       write function for tty
2558  *      @tty: tty device
2559  *      @file: file object
2560  *      @buf: userspace buffer pointer
2561  *      @nr: size of I/O
2562  *
2563  *      Called when the owner of the device wants to send a frame
2564  *      itself (or some other control data). The data is transferred
2565  *      as-is and must be properly framed and checksummed as appropriate
2566  *      by userspace. Frames are either sent whole or not at all as this
2567  *      avoids pain user side.
2568  */
2569 
2570 static ssize_t gsmld_write(struct tty_struct *tty, struct file *file,
2571                            const unsigned char *buf, size_t nr)
2572 {
2573         int space = tty_write_room(tty);
2574         if (space >= nr)
2575                 return tty->ops->write(tty, buf, nr);
2576         set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
2577         return -ENOBUFS;
2578 }
2579 
2580 /**
2581  *      gsmld_poll              -       poll method for N_GSM0710
2582  *      @tty: terminal device
2583  *      @file: file accessing it
2584  *      @wait: poll table
2585  *
2586  *      Called when the line discipline is asked to poll() for data or
2587  *      for special events. This code is not serialized with respect to
2588  *      other events save open/close.
2589  *
2590  *      This code must be sure never to sleep through a hangup.
2591  *      Called without the kernel lock held - fine
2592  */
2593 
2594 static __poll_t gsmld_poll(struct tty_struct *tty, struct file *file,
2595                                                         poll_table *wait)
2596 {
2597         __poll_t mask = 0;
2598         struct gsm_mux *gsm = tty->disc_data;
2599 
2600         poll_wait(file, &tty->read_wait, wait);
2601         poll_wait(file, &tty->write_wait, wait);
2602         if (tty_hung_up_p(file))
2603                 mask |= EPOLLHUP;
2604         if (!tty_is_writelocked(tty) && tty_write_room(tty) > 0)
2605                 mask |= EPOLLOUT | EPOLLWRNORM;
2606         if (gsm->dead)
2607                 mask |= EPOLLHUP;
2608         return mask;
2609 }
2610 
2611 static int gsmld_ioctl(struct tty_struct *tty, struct file *file,
2612                        unsigned int cmd, unsigned long arg)
2613 {
2614         struct gsm_config c;
2615         struct gsm_mux *gsm = tty->disc_data;
2616         unsigned int base;
2617 
2618         switch (cmd) {
2619         case GSMIOC_GETCONF:
2620                 gsm_copy_config_values(gsm, &c);
2621                 if (copy_to_user((void *)arg, &c, sizeof(c)))
2622                         return -EFAULT;
2623                 return 0;
2624         case GSMIOC_SETCONF:
2625                 if (copy_from_user(&c, (void *)arg, sizeof(c)))
2626                         return -EFAULT;
2627                 return gsm_config(gsm, &c);
2628         case GSMIOC_GETFIRST:
2629                 base = mux_num_to_base(gsm);
2630                 return put_user(base + 1, (__u32 __user *)arg);
2631         default:
2632                 return n_tty_ioctl_helper(tty, file, cmd, arg);
2633         }
2634 }
2635 
2636 /*
2637  *      Network interface
2638  *
2639  */
2640 
2641 static int gsm_mux_net_open(struct net_device *net)
2642 {
2643         pr_debug("%s called\n", __func__);
2644         netif_start_queue(net);
2645         return 0;
2646 }
2647 
2648 static int gsm_mux_net_close(struct net_device *net)
2649 {
2650         netif_stop_queue(net);
2651         return 0;
2652 }
2653 
2654 static void dlci_net_free(struct gsm_dlci *dlci)
2655 {
2656         if (!dlci->net) {
2657                 WARN_ON(1);
2658                 return;
2659         }
2660         dlci->adaption = dlci->prev_adaption;
2661         dlci->data = dlci->prev_data;
2662         free_netdev(dlci->net);
2663         dlci->net = NULL;
2664 }
2665 static void net_free(struct kref *ref)
2666 {
2667         struct gsm_mux_net *mux_net;
2668         struct gsm_dlci *dlci;
2669 
2670         mux_net = container_of(ref, struct gsm_mux_net, ref);
2671         dlci = mux_net->dlci;
2672 
2673         if (dlci->net) {
2674                 unregister_netdev(dlci->net);
2675                 dlci_net_free(dlci);
2676         }
2677 }
2678 
2679 static inline void muxnet_get(struct gsm_mux_net *mux_net)
2680 {
2681         kref_get(&mux_net->ref);
2682 }
2683 
2684 static inline void muxnet_put(struct gsm_mux_net *mux_net)
2685 {
2686         kref_put(&mux_net->ref, net_free);
2687 }
2688 
2689 static netdev_tx_t gsm_mux_net_start_xmit(struct sk_buff *skb,
2690                                       struct net_device *net)
2691 {
2692         struct gsm_mux_net *mux_net = netdev_priv(net);
2693         struct gsm_dlci *dlci = mux_net->dlci;
2694         muxnet_get(mux_net);
2695 
2696         skb_queue_head(&dlci->skb_list, skb);
2697         net->stats.tx_packets++;
2698         net->stats.tx_bytes += skb->len;
2699         gsm_dlci_data_kick(dlci);
2700         /* And tell the kernel when the last transmit started. */
2701         netif_trans_update(net);
2702         muxnet_put(mux_net);
2703         return NETDEV_TX_OK;
2704 }
2705 
2706 /* called when a packet did not ack after watchdogtimeout */
2707 static void gsm_mux_net_tx_timeout(struct net_device *net)
2708 {
2709         /* Tell syslog we are hosed. */
2710         dev_dbg(&net->dev, "Tx timed out.\n");
2711 
2712         /* Update statistics */
2713         net->stats.tx_errors++;
2714 }
2715 
2716 static void gsm_mux_rx_netchar(struct gsm_dlci *dlci,
2717                                 const unsigned char *in_buf, int size)
2718 {
2719         struct net_device *net = dlci->net;
2720         struct sk_buff *skb;
2721         struct gsm_mux_net *mux_net = netdev_priv(net);
2722         muxnet_get(mux_net);
2723 
2724         /* Allocate an sk_buff */
2725         skb = dev_alloc_skb(size + NET_IP_ALIGN);
2726         if (!skb) {
2727                 /* We got no receive buffer. */
2728                 net->stats.rx_dropped++;
2729                 muxnet_put(mux_net);
2730                 return;
2731         }
2732         skb_reserve(skb, NET_IP_ALIGN);
2733         skb_put_data(skb, in_buf, size);
2734 
2735         skb->dev = net;
2736         skb->protocol = htons(ETH_P_IP);
2737 
2738         /* Ship it off to the kernel */
2739         netif_rx(skb);
2740 
2741         /* update out statistics */
2742         net->stats.rx_packets++;
2743         net->stats.rx_bytes += size;
2744         muxnet_put(mux_net);
2745         return;
2746 }
2747 
2748 static void gsm_mux_net_init(struct net_device *net)
2749 {
2750         static const struct net_device_ops gsm_netdev_ops = {
2751                 .ndo_open               = gsm_mux_net_open,
2752                 .ndo_stop               = gsm_mux_net_close,
2753                 .ndo_start_xmit         = gsm_mux_net_start_xmit,
2754                 .ndo_tx_timeout         = gsm_mux_net_tx_timeout,
2755         };
2756 
2757         net->netdev_ops = &gsm_netdev_ops;
2758 
2759         /* fill in the other fields */
2760         net->watchdog_timeo = GSM_NET_TX_TIMEOUT;
2761         net->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
2762         net->type = ARPHRD_NONE;
2763         net->tx_queue_len = 10;
2764 }
2765 
2766 
2767 /* caller holds the dlci mutex */
2768 static void gsm_destroy_network(struct gsm_dlci *dlci)
2769 {
2770         struct gsm_mux_net *mux_net;
2771 
2772         pr_debug("destroy network interface");
2773         if (!dlci->net)
2774                 return;
2775         mux_net = netdev_priv(dlci->net);
2776         muxnet_put(mux_net);
2777 }
2778 
2779 
2780 /* caller holds the dlci mutex */
2781 static int gsm_create_network(struct gsm_dlci *dlci, struct gsm_netconfig *nc)
2782 {
2783         char *netname;
2784         int retval = 0;
2785         struct net_device *net;
2786         struct gsm_mux_net *mux_net;
2787 
2788         if (!capable(CAP_NET_ADMIN))
2789                 return -EPERM;
2790 
2791         /* Already in a non tty mode */
2792         if (dlci->adaption > 2)
2793                 return -EBUSY;
2794 
2795         if (nc->protocol != htons(ETH_P_IP))
2796                 return -EPROTONOSUPPORT;
2797 
2798         if (nc->adaption != 3 && nc->adaption != 4)
2799                 return -EPROTONOSUPPORT;
2800 
2801         pr_debug("create network interface");
2802 
2803         netname = "gsm%d";
2804         if (nc->if_name[0] != '\0')
2805                 netname = nc->if_name;
2806         net = alloc_netdev(sizeof(struct gsm_mux_net), netname,
2807                            NET_NAME_UNKNOWN, gsm_mux_net_init);
2808         if (!net) {
2809                 pr_err("alloc_netdev failed");
2810                 return -ENOMEM;
2811         }
2812         net->mtu = dlci->gsm->mtu;
2813         net->min_mtu = 8;
2814         net->max_mtu = dlci->gsm->mtu;
2815         mux_net = netdev_priv(net);
2816         mux_net->dlci = dlci;
2817         kref_init(&mux_net->ref);
2818         strncpy(nc->if_name, net->name, IFNAMSIZ); /* return net name */
2819 
2820         /* reconfigure dlci for network */
2821         dlci->prev_adaption = dlci->adaption;
2822         dlci->prev_data = dlci->data;
2823         dlci->adaption = nc->adaption;
2824         dlci->data = gsm_mux_rx_netchar;
2825         dlci->net = net;
2826 
2827         pr_debug("register netdev");
2828         retval = register_netdev(net);
2829         if (retval) {
2830                 pr_err("network register fail %d\n", retval);
2831                 dlci_net_free(dlci);
2832                 return retval;
2833         }
2834         return net->ifindex;    /* return network index */
2835 }
2836 
2837 /* Line discipline for real tty */
2838 static struct tty_ldisc_ops tty_ldisc_packet = {
2839         .owner           = THIS_MODULE,
2840         .magic           = TTY_LDISC_MAGIC,
2841         .name            = "n_gsm",
2842         .open            = gsmld_open,
2843         .close           = gsmld_close,
2844         .flush_buffer    = gsmld_flush_buffer,
2845         .read            = gsmld_read,
2846         .write           = gsmld_write,
2847         .ioctl           = gsmld_ioctl,
2848         .poll            = gsmld_poll,
2849         .receive_buf     = gsmld_receive_buf,
2850         .write_wakeup    = gsmld_write_wakeup
2851 };
2852 
2853 /*
2854  *      Virtual tty side
2855  */
2856 
2857 #define TX_SIZE         512
2858 
2859 static int gsmtty_modem_update(struct gsm_dlci *dlci, u8 brk)
2860 {
2861         u8 modembits[5];
2862         struct gsm_control *ctrl;
2863         int len = 2;
2864 
2865         if (brk)
2866                 len++;
2867 
2868         modembits[0] = len << 1 | EA;           /* Data bytes */
2869         modembits[1] = dlci->addr << 2 | 3;     /* DLCI, EA, 1 */
2870         modembits[2] = gsm_encode_modem(dlci) << 1 | EA;
2871         if (brk)
2872                 modembits[3] = brk << 4 | 2 | EA;       /* Valid, EA */
2873         ctrl = gsm_control_send(dlci->gsm, CMD_MSC, modembits, len + 1);
2874         if (ctrl == NULL)
2875                 return -ENOMEM;
2876         return gsm_control_wait(dlci->gsm, ctrl);
2877 }
2878 
2879 static int gsm_carrier_raised(struct tty_port *port)
2880 {
2881         struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
2882         struct gsm_mux *gsm = dlci->gsm;
2883 
2884         /* Not yet open so no carrier info */
2885         if (dlci->state != DLCI_OPEN)
2886                 return 0;
2887         if (debug & 2)
2888                 return 1;
2889 
2890         /*
2891          * Basic mode with control channel in ADM mode may not respond
2892          * to CMD_MSC at all and modem_rx is empty.
2893          */
2894         if (gsm->encoding == 0 && gsm->dlci[0]->mode == DLCI_MODE_ADM &&
2895             !dlci->modem_rx)
2896                 return 1;
2897 
2898         return dlci->modem_rx & TIOCM_CD;
2899 }
2900 
2901 static void gsm_dtr_rts(struct tty_port *port, int onoff)
2902 {
2903         struct gsm_dlci *dlci = container_of(port, struct gsm_dlci, port);
2904         unsigned int modem_tx = dlci->modem_tx;
2905         if (onoff)
2906                 modem_tx |= TIOCM_DTR | TIOCM_RTS;
2907         else
2908                 modem_tx &= ~(TIOCM_DTR | TIOCM_RTS);
2909         if (modem_tx != dlci->modem_tx) {
2910                 dlci->modem_tx = modem_tx;
2911                 gsmtty_modem_update(dlci, 0);
2912         }
2913 }
2914 
2915 static const struct tty_port_operations gsm_port_ops = {
2916         .carrier_raised = gsm_carrier_raised,
2917         .dtr_rts = gsm_dtr_rts,
2918         .destruct = gsm_dlci_free,
2919 };
2920 
2921 static int gsmtty_install(struct tty_driver *driver, struct tty_struct *tty)
2922 {
2923         struct gsm_mux *gsm;
2924         struct gsm_dlci *dlci;
2925         unsigned int line = tty->index;
2926         unsigned int mux = mux_line_to_num(line);
2927         bool alloc = false;
2928         int ret;
2929 
2930         line = line & 0x3F;
2931 
2932         if (mux >= MAX_MUX)
2933                 return -ENXIO;
2934         /* FIXME: we need to lock gsm_mux for lifetimes of ttys eventually */
2935         if (gsm_mux[mux] == NULL)
2936                 return -EUNATCH;
2937         if (line == 0 || line > 61)     /* 62/63 reserved */
2938                 return -ECHRNG;
2939         gsm = gsm_mux[mux];
2940         if (gsm->dead)
2941                 return -EL2HLT;
2942         /* If DLCI 0 is not yet fully open return an error.
2943         This is ok from a locking
2944         perspective as we don't have to worry about this
2945         if DLCI0 is lost */
2946         mutex_lock(&gsm->mutex);
2947         if (gsm->dlci[0] && gsm->dlci[0]->state != DLCI_OPEN) {
2948                 mutex_unlock(&gsm->mutex);
2949                 return -EL2NSYNC;
2950         }
2951         dlci = gsm->dlci[line];
2952         if (dlci == NULL) {
2953                 alloc = true;
2954                 dlci = gsm_dlci_alloc(gsm, line);
2955         }
2956         if (dlci == NULL) {
2957                 mutex_unlock(&gsm->mutex);
2958                 return -ENOMEM;
2959         }
2960         ret = tty_port_install(&dlci->port, driver, tty);
2961         if (ret) {
2962                 if (alloc)
2963                         dlci_put(dlci);
2964                 mutex_unlock(&gsm->mutex);
2965                 return ret;
2966         }
2967 
2968         dlci_get(dlci);
2969         dlci_get(gsm->dlci[0]);
2970         mux_get(gsm);
2971         tty->driver_data = dlci;
2972         mutex_unlock(&gsm->mutex);
2973 
2974         return 0;
2975 }
2976 
2977 static int gsmtty_open(struct tty_struct *tty, struct file *filp)
2978 {
2979         struct gsm_dlci *dlci = tty->driver_data;
2980         struct tty_port *port = &dlci->port;
2981 
2982         port->count++;
2983         tty_port_tty_set(port, tty);
2984 
2985         dlci->modem_rx = 0;
2986         /* We could in theory open and close before we wait - eg if we get
2987            a DM straight back. This is ok as that will have caused a hangup */
2988         tty_port_set_initialized(port, 1);
2989         /* Start sending off SABM messages */
2990         gsm_dlci_begin_open(dlci);
2991         /* And wait for virtual carrier */
2992         return tty_port_block_til_ready(port, tty, filp);
2993 }
2994 
2995 static void gsmtty_close(struct tty_struct *tty, struct file *filp)
2996 {
2997         struct gsm_dlci *dlci = tty->driver_data;
2998 
2999         if (dlci == NULL)
3000                 return;
3001         if (dlci->state == DLCI_CLOSED)
3002                 return;
3003         mutex_lock(&dlci->mutex);
3004         gsm_destroy_network(dlci);
3005         mutex_unlock(&dlci->mutex);
3006         if (tty_port_close_start(&dlci->port, tty, filp) == 0)
3007                 return;
3008         gsm_dlci_begin_close(dlci);
3009         if (tty_port_initialized(&dlci->port) && C_HUPCL(tty))
3010                 tty_port_lower_dtr_rts(&dlci->port);
3011         tty_port_close_end(&dlci->port, tty);
3012         tty_port_tty_set(&dlci->port, NULL);
3013         return;
3014 }
3015 
3016 static void gsmtty_hangup(struct tty_struct *tty)
3017 {
3018         struct gsm_dlci *dlci = tty->driver_data;
3019         if (dlci->state == DLCI_CLOSED)
3020                 return;
3021         tty_port_hangup(&dlci->port);
3022         gsm_dlci_begin_close(dlci);
3023 }
3024 
3025 static int gsmtty_write(struct tty_struct *tty, const unsigned char *buf,
3026                                                                     int len)
3027 {
3028         int sent;
3029         struct gsm_dlci *dlci = tty->driver_data;
3030         if (dlci->state == DLCI_CLOSED)
3031                 return -EINVAL;
3032         /* Stuff the bytes into the fifo queue */
3033         sent = kfifo_in_locked(dlci->fifo, buf, len, &dlci->lock);
3034         /* Need to kick the channel */
3035         gsm_dlci_data_kick(dlci);
3036         return sent;
3037 }
3038 
3039 static int gsmtty_write_room(struct tty_struct *tty)
3040 {
3041         struct gsm_dlci *dlci = tty->driver_data;
3042         if (dlci->state == DLCI_CLOSED)
3043                 return -EINVAL;
3044         return TX_SIZE - kfifo_len(dlci->fifo);
3045 }
3046 
3047 static int gsmtty_chars_in_buffer(struct tty_struct *tty)
3048 {
3049         struct gsm_dlci *dlci = tty->driver_data;
3050         if (dlci->state == DLCI_CLOSED)
3051                 return -EINVAL;
3052         return kfifo_len(dlci->fifo);
3053 }
3054 
3055 static void gsmtty_flush_buffer(struct tty_struct *tty)
3056 {
3057         struct gsm_dlci *dlci = tty->driver_data;
3058         if (dlci->state == DLCI_CLOSED)
3059                 return;
3060         /* Caution needed: If we implement reliable transport classes
3061            then the data being transmitted can't simply be junked once
3062            it has first hit the stack. Until then we can just blow it
3063            away */
3064         kfifo_reset(dlci->fifo);
3065         /* Need to unhook this DLCI from the transmit queue logic */
3066 }
3067 
3068 static void gsmtty_wait_until_sent(struct tty_struct *tty, int timeout)
3069 {
3070         /* The FIFO handles the queue so the kernel will do the right
3071            thing waiting on chars_in_buffer before calling us. No work
3072            to do here */
3073 }
3074 
3075 static int gsmtty_tiocmget(struct tty_struct *tty)
3076 {
3077         struct gsm_dlci *dlci = tty->driver_data;
3078         if (dlci->state == DLCI_CLOSED)
3079                 return -EINVAL;
3080         return dlci->modem_rx;
3081 }
3082 
3083 static int gsmtty_tiocmset(struct tty_struct *tty,
3084         unsigned int set, unsigned int clear)
3085 {
3086         struct gsm_dlci *dlci = tty->driver_data;
3087         unsigned int modem_tx = dlci->modem_tx;
3088 
3089         if (dlci->state == DLCI_CLOSED)
3090                 return -EINVAL;
3091         modem_tx &= ~clear;
3092         modem_tx |= set;
3093 
3094         if (modem_tx != dlci->modem_tx) {
3095                 dlci->modem_tx = modem_tx;
3096                 return gsmtty_modem_update(dlci, 0);
3097         }
3098         return 0;
3099 }
3100 
3101 
3102 static int gsmtty_ioctl(struct tty_struct *tty,
3103                         unsigned int cmd, unsigned long arg)
3104 {
3105         struct gsm_dlci *dlci = tty->driver_data;
3106         struct gsm_netconfig nc;
3107         int index;
3108 
3109         if (dlci->state == DLCI_CLOSED)
3110                 return -EINVAL;
3111         switch (cmd) {
3112         case GSMIOC_ENABLE_NET:
3113                 if (copy_from_user(&nc, (void __user *)arg, sizeof(nc)))
3114                         return -EFAULT;
3115                 nc.if_name[IFNAMSIZ-1] = '\0';
3116                 /* return net interface index or error code */
3117                 mutex_lock(&dlci->mutex);
3118                 index = gsm_create_network(dlci, &nc);
3119                 mutex_unlock(&dlci->mutex);
3120                 if (copy_to_user((void __user *)arg, &nc, sizeof(nc)))
3121                         return -EFAULT;
3122                 return index;
3123         case GSMIOC_DISABLE_NET:
3124                 if (!capable(CAP_NET_ADMIN))
3125                         return -EPERM;
3126                 mutex_lock(&dlci->mutex);
3127                 gsm_destroy_network(dlci);
3128                 mutex_unlock(&dlci->mutex);
3129                 return 0;
3130         default:
3131                 return -ENOIOCTLCMD;
3132         }
3133 }
3134 
3135 static void gsmtty_set_termios(struct tty_struct *tty, struct ktermios *old)
3136 {
3137         struct gsm_dlci *dlci = tty->driver_data;
3138         if (dlci->state == DLCI_CLOSED)
3139                 return;
3140         /* For the moment its fixed. In actual fact the speed information
3141            for the virtual channel can be propogated in both directions by
3142            the RPN control message. This however rapidly gets nasty as we
3143            then have to remap modem signals each way according to whether
3144            our virtual cable is null modem etc .. */
3145         tty_termios_copy_hw(&tty->termios, old);
3146 }
3147 
3148 static void gsmtty_throttle(struct tty_struct *tty)
3149 {
3150         struct gsm_dlci *dlci = tty->driver_data;
3151         if (dlci->state == DLCI_CLOSED)
3152                 return;
3153         if (C_CRTSCTS(tty))
3154                 dlci->modem_tx &= ~TIOCM_DTR;
3155         dlci->throttled = 1;
3156         /* Send an MSC with DTR cleared */
3157         gsmtty_modem_update(dlci, 0);
3158 }
3159 
3160 static void gsmtty_unthrottle(struct tty_struct *tty)
3161 {
3162         struct gsm_dlci *dlci = tty->driver_data;
3163         if (dlci->state == DLCI_CLOSED)
3164                 return;
3165         if (C_CRTSCTS(tty))
3166                 dlci->modem_tx |= TIOCM_DTR;
3167         dlci->throttled = 0;
3168         /* Send an MSC with DTR set */
3169         gsmtty_modem_update(dlci, 0);
3170 }
3171 
3172 static int gsmtty_break_ctl(struct tty_struct *tty, int state)
3173 {
3174         struct gsm_dlci *dlci = tty->driver_data;
3175         int encode = 0; /* Off */
3176         if (dlci->state == DLCI_CLOSED)
3177                 return -EINVAL;
3178 
3179         if (state == -1)        /* "On indefinitely" - we can't encode this
3180                                     properly */
3181                 encode = 0x0F;
3182         else if (state > 0) {
3183                 encode = state / 200;   /* mS to encoding */
3184                 if (encode > 0x0F)
3185                         encode = 0x0F;  /* Best effort */
3186         }
3187         return gsmtty_modem_update(dlci, encode);
3188 }
3189 
3190 static void gsmtty_cleanup(struct tty_struct *tty)
3191 {
3192         struct gsm_dlci *dlci = tty->driver_data;
3193         struct gsm_mux *gsm = dlci->gsm;
3194 
3195         dlci_put(dlci);
3196         dlci_put(gsm->dlci[0]);
3197         mux_put(gsm);
3198 }
3199 
3200 /* Virtual ttys for the demux */
3201 static const struct tty_operations gsmtty_ops = {
3202         .install                = gsmtty_install,
3203         .open                   = gsmtty_open,
3204         .close                  = gsmtty_close,
3205         .write                  = gsmtty_write,
3206         .write_room             = gsmtty_write_room,
3207         .chars_in_buffer        = gsmtty_chars_in_buffer,
3208         .flush_buffer           = gsmtty_flush_buffer,
3209         .ioctl                  = gsmtty_ioctl,
3210         .throttle               = gsmtty_throttle,
3211         .unthrottle             = gsmtty_unthrottle,
3212         .set_termios            = gsmtty_set_termios,
3213         .hangup                 = gsmtty_hangup,
3214         .wait_until_sent        = gsmtty_wait_until_sent,
3215         .tiocmget               = gsmtty_tiocmget,
3216         .tiocmset               = gsmtty_tiocmset,
3217         .break_ctl              = gsmtty_break_ctl,
3218         .cleanup                = gsmtty_cleanup,
3219 };
3220 
3221 
3222 
3223 static int __init gsm_init(void)
3224 {
3225         /* Fill in our line protocol discipline, and register it */
3226         int status = tty_register_ldisc(N_GSM0710, &tty_ldisc_packet);
3227         if (status != 0) {
3228                 pr_err("n_gsm: can't register line discipline (err = %d)\n",
3229                                                                 status);
3230                 return status;
3231         }
3232 
3233         gsm_tty_driver = alloc_tty_driver(256);
3234         if (!gsm_tty_driver) {
3235                 tty_unregister_ldisc(N_GSM0710);
3236                 pr_err("gsm_init: tty allocation failed.\n");
3237                 return -EINVAL;
3238         }
3239         gsm_tty_driver->driver_name     = "gsmtty";
3240         gsm_tty_driver->name            = "gsmtty";
3241         gsm_tty_driver->major           = 0;    /* Dynamic */
3242         gsm_tty_driver->minor_start     = 0;
3243         gsm_tty_driver->type            = TTY_DRIVER_TYPE_SERIAL;
3244         gsm_tty_driver->subtype = SERIAL_TYPE_NORMAL;
3245         gsm_tty_driver->flags   = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV
3246                                                 | TTY_DRIVER_HARDWARE_BREAK;
3247         gsm_tty_driver->init_termios    = tty_std_termios;
3248         /* Fixme */
3249         gsm_tty_driver->init_termios.c_lflag &= ~ECHO;
3250         tty_set_operations(gsm_tty_driver, &gsmtty_ops);
3251 
3252         spin_lock_init(&gsm_mux_lock);
3253 
3254         if (tty_register_driver(gsm_tty_driver)) {
3255                 put_tty_driver(gsm_tty_driver);
3256                 tty_unregister_ldisc(N_GSM0710);
3257                 pr_err("gsm_init: tty registration failed.\n");
3258                 return -EBUSY;
3259         }
3260         pr_debug("gsm_init: loaded as %d,%d.\n",
3261                         gsm_tty_driver->major, gsm_tty_driver->minor_start);
3262         return 0;
3263 }
3264 
3265 static void __exit gsm_exit(void)
3266 {
3267         int status = tty_unregister_ldisc(N_GSM0710);
3268         if (status != 0)
3269                 pr_err("n_gsm: can't unregister line discipline (err = %d)\n",
3270                                                                 status);
3271         tty_unregister_driver(gsm_tty_driver);
3272         put_tty_driver(gsm_tty_driver);
3273 }
3274 
3275 module_init(gsm_init);
3276 module_exit(gsm_exit);
3277 
3278 
3279 MODULE_LICENSE("GPL");
3280 MODULE_ALIAS_LDISC(N_GSM0710);
/* [<][>][^][v][top][bottom][index][help] */
root/drivers/tty/n_gsm.c

DEFINITIONS
