1#ifndef _LINUX_TTY_LDISC_H
2#define _LINUX_TTY_LDISC_H
3
4/*
5 * This structure defines the interface between the tty line discipline
6 * implementation and the tty routines.  The following routines can be
7 * defined; unless noted otherwise, they are optional, and can be
8 * filled in with a null pointer.
9 *
10 * int	(*open)(struct tty_struct *);
11 *
12 *	This function is called when the line discipline is associated
13 *	with the tty.  The line discipline can use this as an
14 *	opportunity to initialize any state needed by the ldisc routines.
15 *
16 * void	(*close)(struct tty_struct *);
17 *
18 *	This function is called when the line discipline is being
19 *	shutdown, either because the tty is being closed or because
20 *	the tty is being changed to use a new line discipline
21 *
22 * void	(*flush_buffer)(struct tty_struct *tty);
23 *
24 *	This function instructs the line discipline to clear its
25 *	buffers of any input characters it may have queued to be
26 *	delivered to the user mode process.
27 *
28 * ssize_t (*chars_in_buffer)(struct tty_struct *tty);
29 *
30 *	This function returns the number of input characters the line
31 *	discipline may have queued up to be delivered to the user mode
32 *	process.
33 *
34 * ssize_t (*read)(struct tty_struct * tty, struct file * file,
35 *		   unsigned char * buf, size_t nr);
36 *
37 *	This function is called when the user requests to read from
38 *	the tty.  The line discipline will return whatever characters
39 *	it has buffered up for the user.  If this function is not
40 *	defined, the user will receive an EIO error.
41 *
42 * ssize_t (*write)(struct tty_struct * tty, struct file * file,
43 *		    const unsigned char * buf, size_t nr);
44 *
45 *	This function is called when the user requests to write to the
46 *	tty.  The line discipline will deliver the characters to the
47 *	low-level tty device for transmission, optionally performing
48 *	some processing on the characters first.  If this function is
49 *	not defined, the user will receive an EIO error.
50 *
51 * int	(*ioctl)(struct tty_struct * tty, struct file * file,
52 *		 unsigned int cmd, unsigned long arg);
53 *
54 *	This function is called when the user requests an ioctl which
55 *	is not handled by the tty layer or the low-level tty driver.
56 *	It is intended for ioctls which affect line discpline
57 *	operation.  Note that the search order for ioctls is (1) tty
58 *	layer, (2) tty low-level driver, (3) line discpline.  So a
59 *	low-level driver can "grab" an ioctl request before the line
60 *	discpline has a chance to see it.
61 *
62 * long	(*compat_ioctl)(struct tty_struct * tty, struct file * file,
63 *		        unsigned int cmd, unsigned long arg);
64 *
65 *	Process ioctl calls from 32-bit process on 64-bit system
66 *
67 * void	(*set_termios)(struct tty_struct *tty, struct ktermios * old);
68 *
69 *	This function notifies the line discpline that a change has
70 *	been made to the termios structure.
71 *
72 * int	(*poll)(struct tty_struct * tty, struct file * file,
73 *		  poll_table *wait);
74 *
75 *	This function is called when a user attempts to select/poll on a
76 *	tty device.  It is solely the responsibility of the line
77 *	discipline to handle poll requests.
78 *
79 * void	(*receive_buf)(struct tty_struct *, const unsigned char *cp,
80 *		       char *fp, int count);
81 *
82 *	This function is called by the low-level tty driver to send
83 *	characters received by the hardware to the line discpline for
84 *	processing.  <cp> is a pointer to the buffer of input
85 *	character received by the device.  <fp> is a pointer to a
86 *	pointer of flag bytes which indicate whether a character was
87 *	received with a parity error, etc. <fp> may be NULL to indicate
88 *	all data received is TTY_NORMAL.
89 *
90 * void	(*write_wakeup)(struct tty_struct *);
91 *
92 *	This function is called by the low-level tty driver to signal
93 *	that line discpline should try to send more characters to the
94 *	low-level driver for transmission.  If the line discpline does
95 *	not have any more data to send, it can just return. If the line
96 *	discipline does have some data to send, please arise a tasklet
97 *	or workqueue to do the real data transfer. Do not send data in
98 *	this hook, it may leads to a deadlock.
99 *
100 * int (*hangup)(struct tty_struct *)
101 *
102 *	Called on a hangup. Tells the discipline that it should
103 *	cease I/O to the tty driver. Can sleep. The driver should
104 *	seek to perform this action quickly but should wait until
105 *	any pending driver I/O is completed.
106 *
107 * void (*fasync)(struct tty_struct *, int on)
108 *
109 *	Notify line discipline when signal-driven I/O is enabled or
110 *	disabled.
111 *
112 * void (*dcd_change)(struct tty_struct *tty, unsigned int status)
113 *
114 *	Tells the discipline that the DCD pin has changed its status.
115 *	Used exclusively by the N_PPS (Pulse-Per-Second) line discipline.
116 *
117 * int	(*receive_buf2)(struct tty_struct *, const unsigned char *cp,
118 *			char *fp, int count);
119 *
120 *	This function is called by the low-level tty driver to send
121 *	characters received by the hardware to the line discpline for
122 *	processing.  <cp> is a pointer to the buffer of input
123 *	character received by the device.  <fp> is a pointer to a
124 *	pointer of flag bytes which indicate whether a character was
125 *	received with a parity error, etc. <fp> may be NULL to indicate
126 *	all data received is TTY_NORMAL.
127 *	If assigned, prefer this function for automatic flow control.
128 */
129
130#include <linux/fs.h>
131#include <linux/wait.h>
132
133
134/*
135 * the semaphore definition
136 */
137struct ld_semaphore {
138	long			count;
139	raw_spinlock_t		wait_lock;
140	unsigned int		wait_readers;
141	struct list_head	read_wait;
142	struct list_head	write_wait;
143#ifdef CONFIG_DEBUG_LOCK_ALLOC
144	struct lockdep_map	dep_map;
145#endif
146};
147
148extern void __init_ldsem(struct ld_semaphore *sem, const char *name,
149			 struct lock_class_key *key);
150
151#define init_ldsem(sem)						\
152do {								\
153	static struct lock_class_key __key;			\
154								\
155	__init_ldsem((sem), #sem, &__key);			\
156} while (0)
157
158
159extern int ldsem_down_read(struct ld_semaphore *sem, long timeout);
160extern int ldsem_down_read_trylock(struct ld_semaphore *sem);
161extern int ldsem_down_write(struct ld_semaphore *sem, long timeout);
162extern int ldsem_down_write_trylock(struct ld_semaphore *sem);
163extern void ldsem_up_read(struct ld_semaphore *sem);
164extern void ldsem_up_write(struct ld_semaphore *sem);
165
166#ifdef CONFIG_DEBUG_LOCK_ALLOC
167extern int ldsem_down_read_nested(struct ld_semaphore *sem, int subclass,
168				  long timeout);
169extern int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass,
170				   long timeout);
171#else
172# define ldsem_down_read_nested(sem, subclass, timeout)		\
173		ldsem_down_read(sem, timeout)
174# define ldsem_down_write_nested(sem, subclass, timeout)	\
175		ldsem_down_write(sem, timeout)
176#endif
177
178
179struct tty_ldisc_ops {
180	int	magic;
181	char	*name;
182	int	num;
183	int	flags;
184
185	/*
186	 * The following routines are called from above.
187	 */
188	int	(*open)(struct tty_struct *);
189	void	(*close)(struct tty_struct *);
190	void	(*flush_buffer)(struct tty_struct *tty);
191	ssize_t	(*chars_in_buffer)(struct tty_struct *tty);
192	ssize_t	(*read)(struct tty_struct *tty, struct file *file,
193			unsigned char __user *buf, size_t nr);
194	ssize_t	(*write)(struct tty_struct *tty, struct file *file,
195			 const unsigned char *buf, size_t nr);
196	int	(*ioctl)(struct tty_struct *tty, struct file *file,
197			 unsigned int cmd, unsigned long arg);
198	long	(*compat_ioctl)(struct tty_struct *tty, struct file *file,
199				unsigned int cmd, unsigned long arg);
200	void	(*set_termios)(struct tty_struct *tty, struct ktermios *old);
201	unsigned int (*poll)(struct tty_struct *, struct file *,
202			     struct poll_table_struct *);
203	int	(*hangup)(struct tty_struct *tty);
204
205	/*
206	 * The following routines are called from below.
207	 */
208	void	(*receive_buf)(struct tty_struct *, const unsigned char *cp,
209			       char *fp, int count);
210	void	(*write_wakeup)(struct tty_struct *);
211	void	(*dcd_change)(struct tty_struct *, unsigned int);
212	void	(*fasync)(struct tty_struct *tty, int on);
213	int	(*receive_buf2)(struct tty_struct *, const unsigned char *cp,
214				char *fp, int count);
215
216	struct  module *owner;
217
218	int refcount;
219};
220
221struct tty_ldisc {
222	struct tty_ldisc_ops *ops;
223	struct tty_struct *tty;
224};
225
226#define TTY_LDISC_MAGIC	0x5403
227
228#define LDISC_FLAG_DEFINED	0x00000001
229
230#define MODULE_ALIAS_LDISC(ldisc) \
231	MODULE_ALIAS("tty-ldisc-" __stringify(ldisc))
232
233#endif /* _LINUX_TTY_LDISC_H */
234