root/drivers/platform/chrome/cros_ec_lpc.c

DEFINITIONS

1. cros_ec_lpc_read_bytes
2. cros_ec_lpc_write_bytes
3. cros_ec_lpc_mec_read_bytes
4. cros_ec_lpc_mec_write_bytes
5. ec_response_timed_out
6. cros_ec_pkt_xfer_lpc
7. cros_ec_cmd_xfer_lpc
8. cros_ec_lpc_readmem
9. cros_ec_lpc_acpi_notify
10. cros_ec_lpc_probe
11. cros_ec_lpc_remove
12. cros_ec_lpc_suspend
13. cros_ec_lpc_resume
14. cros_ec_lpc_parse_device
15. cros_ec_lpc_init
16. cros_ec_lpc_exit

   1 // SPDX-License-Identifier: GPL-2.0
   2 // LPC interface for ChromeOS Embedded Controller
   3 //
   4 // Copyright (C) 2012-2015 Google, Inc
   5 //
   6 // This driver uses the ChromeOS EC byte-level message-based protocol for
   7 // communicating the keyboard state (which keys are pressed) from a keyboard EC
   8 // to the AP over some bus (such as i2c, lpc, spi).  The EC does debouncing,
   9 // but everything else (including deghosting) is done here.  The main
  10 // motivation for this is to keep the EC firmware as simple as possible, since
  11 // it cannot be easily upgraded and EC flash/IRAM space is relatively
  12 // expensive.
  13 
  14 #include <linux/acpi.h>
  15 #include <linux/dmi.h>
  16 #include <linux/delay.h>
  17 #include <linux/io.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/module.h>
  20 #include <linux/platform_data/cros_ec_commands.h>
  21 #include <linux/platform_data/cros_ec_proto.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/printk.h>
  24 #include <linux/suspend.h>
  25 
  26 #include "cros_ec_lpc_mec.h"
  27 
  28 #define DRV_NAME "cros_ec_lpcs"
  29 #define ACPI_DRV_NAME "GOOG0004"
  30 
  31 /* True if ACPI device is present */
  32 static bool cros_ec_lpc_acpi_device_found;
  33 
  34 /**
  35  * struct lpc_driver_ops - LPC driver operations
  36  * @read: Copy length bytes from EC address offset into buffer dest. Returns
  37  *        the 8-bit checksum of all bytes read.
  38  * @write: Copy length bytes from buffer msg into EC address offset. Returns
  39  *         the 8-bit checksum of all bytes written.
  40  */
  41 struct lpc_driver_ops {
  42         u8 (*read)(unsigned int offset, unsigned int length, u8 *dest);
  43         u8 (*write)(unsigned int offset, unsigned int length, const u8 *msg);
  44 };
  45 
  46 static struct lpc_driver_ops cros_ec_lpc_ops = { };
  47 
  48 /*
  49  * A generic instance of the read function of struct lpc_driver_ops, used for
  50  * the LPC EC.
  51  */
  52 static u8 cros_ec_lpc_read_bytes(unsigned int offset, unsigned int length,
  53                                  u8 *dest)
  54 {
  55         int sum = 0;
  56         int i;
  57 
  58         for (i = 0; i < length; ++i) {
  59                 dest[i] = inb(offset + i);
  60                 sum += dest[i];
  61         }
  62 
  63         /* Return checksum of all bytes read */
  64         return sum;
  65 }
  66 
  67 /*
  68  * A generic instance of the write function of struct lpc_driver_ops, used for
  69  * the LPC EC.
  70  */
  71 static u8 cros_ec_lpc_write_bytes(unsigned int offset, unsigned int length,
  72                                   const u8 *msg)
  73 {
  74         int sum = 0;
  75         int i;
  76 
  77         for (i = 0; i < length; ++i) {
  78                 outb(msg[i], offset + i);
  79                 sum += msg[i];
  80         }
  81 
  82         /* Return checksum of all bytes written */
  83         return sum;
  84 }
  85 
  86 /*
  87  * An instance of the read function of struct lpc_driver_ops, used for the
  88  * MEC variant of LPC EC.
  89  */
  90 static u8 cros_ec_lpc_mec_read_bytes(unsigned int offset, unsigned int length,
  91                                      u8 *dest)
  92 {
  93         int in_range = cros_ec_lpc_mec_in_range(offset, length);
  94 
  95         if (in_range < 0)
  96                 return 0;
  97 
  98         return in_range ?
  99                 cros_ec_lpc_io_bytes_mec(MEC_IO_READ,
 100                                          offset - EC_HOST_CMD_REGION0,
 101                                          length, dest) :
 102                 cros_ec_lpc_read_bytes(offset, length, dest);
 103 }
 104 
 105 /*
 106  * An instance of the write function of struct lpc_driver_ops, used for the
 107  * MEC variant of LPC EC.
 108  */
 109 static u8 cros_ec_lpc_mec_write_bytes(unsigned int offset, unsigned int length,
 110                                       const u8 *msg)
 111 {
 112         int in_range = cros_ec_lpc_mec_in_range(offset, length);
 113 
 114         if (in_range < 0)
 115                 return 0;
 116 
 117         return in_range ?
 118                 cros_ec_lpc_io_bytes_mec(MEC_IO_WRITE,
 119                                          offset - EC_HOST_CMD_REGION0,
 120                                          length, (u8 *)msg) :
 121                 cros_ec_lpc_write_bytes(offset, length, msg);
 122 }
 123 
 124 static int ec_response_timed_out(void)
 125 {
 126         unsigned long one_second = jiffies + HZ;
 127         u8 data;
 128 
 129         usleep_range(200, 300);
 130         do {
 131                 if (!(cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_CMD, 1, &data) &
 132                     EC_LPC_STATUS_BUSY_MASK))
 133                         return 0;
 134                 usleep_range(100, 200);
 135         } while (time_before(jiffies, one_second));
 136 
 137         return 1;
 138 }
 139 
 140 static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
 141                                 struct cros_ec_command *msg)
 142 {
 143         struct ec_host_response response;
 144         u8 sum;
 145         int ret = 0;
 146         u8 *dout;
 147 
 148         ret = cros_ec_prepare_tx(ec, msg);
 149 
 150         /* Write buffer */
 151         cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_PACKET, ret, ec->dout);
 152 
 153         /* Here we go */
 154         sum = EC_COMMAND_PROTOCOL_3;
 155         cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_CMD, 1, &sum);
 156 
 157         if (ec_response_timed_out()) {
 158                 dev_warn(ec->dev, "EC responsed timed out\n");
 159                 ret = -EIO;
 160                 goto done;
 161         }
 162 
 163         /* Check result */
 164         msg->result = cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_DATA, 1, &sum);
 165         ret = cros_ec_check_result(ec, msg);
 166         if (ret)
 167                 goto done;
 168 
 169         /* Read back response */
 170         dout = (u8 *)&response;
 171         sum = cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_PACKET, sizeof(response),
 172                                    dout);
 173 
 174         msg->result = response.result;
 175 
 176         if (response.data_len > msg->insize) {
 177                 dev_err(ec->dev,
 178                         "packet too long (%d bytes, expected %d)",
 179                         response.data_len, msg->insize);
 180                 ret = -EMSGSIZE;
 181                 goto done;
 182         }
 183 
 184         /* Read response and process checksum */
 185         sum += cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_PACKET +
 186                                     sizeof(response), response.data_len,
 187                                     msg->data);
 188 
 189         if (sum) {
 190                 dev_err(ec->dev,
 191                         "bad packet checksum %02x\n",
 192                         response.checksum);
 193                 ret = -EBADMSG;
 194                 goto done;
 195         }
 196 
 197         /* Return actual amount of data received */
 198         ret = response.data_len;
 199 done:
 200         return ret;
 201 }
 202 
 203 static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
 204                                 struct cros_ec_command *msg)
 205 {
 206         struct ec_lpc_host_args args;
 207         u8 sum;
 208         int ret = 0;
 209 
 210         if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
 211             msg->insize > EC_PROTO2_MAX_PARAM_SIZE) {
 212                 dev_err(ec->dev,
 213                         "invalid buffer sizes (out %d, in %d)\n",
 214                         msg->outsize, msg->insize);
 215                 return -EINVAL;
 216         }
 217 
 218         /* Now actually send the command to the EC and get the result */
 219         args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
 220         args.command_version = msg->version;
 221         args.data_size = msg->outsize;
 222 
 223         /* Initialize checksum */
 224         sum = msg->command + args.flags + args.command_version + args.data_size;
 225 
 226         /* Copy data and update checksum */
 227         sum += cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_PARAM, msg->outsize,
 228                                      msg->data);
 229 
 230         /* Finalize checksum and write args */
 231         args.checksum = sum;
 232         cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
 233                               (u8 *)&args);
 234 
 235         /* Here we go */
 236         sum = msg->command;
 237         cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_CMD, 1, &sum);
 238 
 239         if (ec_response_timed_out()) {
 240                 dev_warn(ec->dev, "EC responsed timed out\n");
 241                 ret = -EIO;
 242                 goto done;
 243         }
 244 
 245         /* Check result */
 246         msg->result = cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_DATA, 1, &sum);
 247         ret = cros_ec_check_result(ec, msg);
 248         if (ret)
 249                 goto done;
 250 
 251         /* Read back args */
 252         cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_ARGS, sizeof(args), (u8 *)&args);
 253 
 254         if (args.data_size > msg->insize) {
 255                 dev_err(ec->dev,
 256                         "packet too long (%d bytes, expected %d)",
 257                         args.data_size, msg->insize);
 258                 ret = -ENOSPC;
 259                 goto done;
 260         }
 261 
 262         /* Start calculating response checksum */
 263         sum = msg->command + args.flags + args.command_version + args.data_size;
 264 
 265         /* Read response and update checksum */
 266         sum += cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_PARAM, args.data_size,
 267                                     msg->data);
 268 
 269         /* Verify checksum */
 270         if (args.checksum != sum) {
 271                 dev_err(ec->dev,
 272                         "bad packet checksum, expected %02x, got %02x\n",
 273                         args.checksum, sum);
 274                 ret = -EBADMSG;
 275                 goto done;
 276         }
 277 
 278         /* Return actual amount of data received */
 279         ret = args.data_size;
 280 done:
 281         return ret;
 282 }
 283 
 284 /* Returns num bytes read, or negative on error. Doesn't need locking. */
 285 static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
 286                                unsigned int bytes, void *dest)
 287 {
 288         int i = offset;
 289         char *s = dest;
 290         int cnt = 0;
 291 
 292         if (offset >= EC_MEMMAP_SIZE - bytes)
 293                 return -EINVAL;
 294 
 295         /* fixed length */
 296         if (bytes) {
 297                 cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + offset, bytes, s);
 298                 return bytes;
 299         }
 300 
 301         /* string */
 302         for (; i < EC_MEMMAP_SIZE; i++, s++) {
 303                 cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + i, 1, s);
 304                 cnt++;
 305                 if (!*s)
 306                         break;
 307         }
 308 
 309         return cnt;
 310 }
 311 
 312 static void cros_ec_lpc_acpi_notify(acpi_handle device, u32 value, void *data)
 313 {
 314         struct cros_ec_device *ec_dev = data;
 315 
 316         if (ec_dev->mkbp_event_supported &&
 317             cros_ec_get_next_event(ec_dev, NULL) > 0)
 318                 blocking_notifier_call_chain(&ec_dev->event_notifier, 0,
 319                                              ec_dev);
 320 
 321         if (value == ACPI_NOTIFY_DEVICE_WAKE)
 322                 pm_system_wakeup();
 323 }
 324 
 325 static int cros_ec_lpc_probe(struct platform_device *pdev)
 326 {
 327         struct device *dev = &pdev->dev;
 328         struct acpi_device *adev;
 329         acpi_status status;
 330         struct cros_ec_device *ec_dev;
 331         u8 buf[2];
 332         int irq, ret;
 333 
 334         if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
 335                                  dev_name(dev))) {
 336                 dev_err(dev, "couldn't reserve memmap region\n");
 337                 return -EBUSY;
 338         }
 339 
 340         /*
 341          * Read the mapped ID twice, the first one is assuming the
 342          * EC is a Microchip Embedded Controller (MEC) variant, if the
 343          * protocol fails, fallback to the non MEC variant and try to
 344          * read again the ID.
 345          */
 346         cros_ec_lpc_ops.read = cros_ec_lpc_mec_read_bytes;
 347         cros_ec_lpc_ops.write = cros_ec_lpc_mec_write_bytes;
 348         cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2, buf);
 349         if (buf[0] != 'E' || buf[1] != 'C') {
 350                 /* Re-assign read/write operations for the non MEC variant */
 351                 cros_ec_lpc_ops.read = cros_ec_lpc_read_bytes;
 352                 cros_ec_lpc_ops.write = cros_ec_lpc_write_bytes;
 353                 cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2,
 354                                      buf);
 355                 if (buf[0] != 'E' || buf[1] != 'C') {
 356                         dev_err(dev, "EC ID not detected\n");
 357                         return -ENODEV;
 358                 }
 359         }
 360 
 361         if (!devm_request_region(dev, EC_HOST_CMD_REGION0,
 362                                  EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
 363                 dev_err(dev, "couldn't reserve region0\n");
 364                 return -EBUSY;
 365         }
 366         if (!devm_request_region(dev, EC_HOST_CMD_REGION1,
 367                                  EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
 368                 dev_err(dev, "couldn't reserve region1\n");
 369                 return -EBUSY;
 370         }
 371 
 372         ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
 373         if (!ec_dev)
 374                 return -ENOMEM;
 375 
 376         platform_set_drvdata(pdev, ec_dev);
 377         ec_dev->dev = dev;
 378         ec_dev->phys_name = dev_name(dev);
 379         ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
 380         ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
 381         ec_dev->cmd_readmem = cros_ec_lpc_readmem;
 382         ec_dev->din_size = sizeof(struct ec_host_response) +
 383                            sizeof(struct ec_response_get_protocol_info);
 384         ec_dev->dout_size = sizeof(struct ec_host_request);
 385 
 386         /*
 387          * Some boards do not have an IRQ allotted for cros_ec_lpc,
 388          * which makes ENXIO an expected (and safe) scenario.
 389          */
 390         irq = platform_get_irq(pdev, 0);
 391         if (irq > 0)
 392                 ec_dev->irq = irq;
 393         else if (irq != -ENXIO) {
 394                 dev_err(dev, "couldn't retrieve IRQ number (%d)\n", irq);
 395                 return irq;
 396         }
 397 
 398         ret = cros_ec_register(ec_dev);
 399         if (ret) {
 400                 dev_err(dev, "couldn't register ec_dev (%d)\n", ret);
 401                 return ret;
 402         }
 403 
 404         /*
 405          * Connect a notify handler to process MKBP messages if we have a
 406          * companion ACPI device.
 407          */
 408         adev = ACPI_COMPANION(dev);
 409         if (adev) {
 410                 status = acpi_install_notify_handler(adev->handle,
 411                                                      ACPI_ALL_NOTIFY,
 412                                                      cros_ec_lpc_acpi_notify,
 413                                                      ec_dev);
 414                 if (ACPI_FAILURE(status))
 415                         dev_warn(dev, "Failed to register notifier %08x\n",
 416                                  status);
 417         }
 418 
 419         return 0;
 420 }
 421 
 422 static int cros_ec_lpc_remove(struct platform_device *pdev)
 423 {
 424         struct cros_ec_device *ec_dev = platform_get_drvdata(pdev);
 425         struct acpi_device *adev;
 426 
 427         adev = ACPI_COMPANION(&pdev->dev);
 428         if (adev)
 429                 acpi_remove_notify_handler(adev->handle, ACPI_ALL_NOTIFY,
 430                                            cros_ec_lpc_acpi_notify);
 431 
 432         return cros_ec_unregister(ec_dev);
 433 }
 434 
 435 static const struct acpi_device_id cros_ec_lpc_acpi_device_ids[] = {
 436         { ACPI_DRV_NAME, 0 },
 437         { }
 438 };
 439 MODULE_DEVICE_TABLE(acpi, cros_ec_lpc_acpi_device_ids);
 440 
 441 static const struct dmi_system_id cros_ec_lpc_dmi_table[] __initconst = {
 442         {
 443                 /*
 444                  * Today all Chromebooks/boxes ship with Google_* as version and
 445                  * coreboot as bios vendor. No other systems with this
 446                  * combination are known to date.
 447                  */
 448                 .matches = {
 449                         DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
 450                         DMI_MATCH(DMI_BIOS_VERSION, "Google_"),
 451                 },
 452         },
 453         {
 454                 /*
 455                  * If the box is running custom coreboot firmware then the
 456                  * DMI BIOS version string will not be matched by "Google_",
 457                  * but the system vendor string will still be matched by
 458                  * "GOOGLE".
 459                  */
 460                 .matches = {
 461                         DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
 462                         DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 463                 },
 464         },
 465         {
 466                 /* x86-link, the Chromebook Pixel. */
 467                 .matches = {
 468                         DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 469                         DMI_MATCH(DMI_PRODUCT_NAME, "Link"),
 470                 },
 471         },
 472         {
 473                 /* x86-samus, the Chromebook Pixel 2. */
 474                 .matches = {
 475                         DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 476                         DMI_MATCH(DMI_PRODUCT_NAME, "Samus"),
 477                 },
 478         },
 479         {
 480                 /* x86-peppy, the Acer C720 Chromebook. */
 481                 .matches = {
 482                         DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
 483                         DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"),
 484                 },
 485         },
 486         {
 487                 /* x86-glimmer, the Lenovo Thinkpad Yoga 11e. */
 488                 .matches = {
 489                         DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 490                         DMI_MATCH(DMI_PRODUCT_NAME, "Glimmer"),
 491                 },
 492         },
 493         { /* sentinel */ }
 494 };
 495 MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table);
 496 
 497 #ifdef CONFIG_PM_SLEEP
 498 static int cros_ec_lpc_suspend(struct device *dev)
 499 {
 500         struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
 501 
 502         return cros_ec_suspend(ec_dev);
 503 }
 504 
 505 static int cros_ec_lpc_resume(struct device *dev)
 506 {
 507         struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
 508 
 509         return cros_ec_resume(ec_dev);
 510 }
 511 #endif
 512 
 513 static const struct dev_pm_ops cros_ec_lpc_pm_ops = {
 514         SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_lpc_suspend, cros_ec_lpc_resume)
 515 };
 516 
 517 static struct platform_driver cros_ec_lpc_driver = {
 518         .driver = {
 519                 .name = DRV_NAME,
 520                 .acpi_match_table = cros_ec_lpc_acpi_device_ids,
 521                 .pm = &cros_ec_lpc_pm_ops,
 522         },
 523         .probe = cros_ec_lpc_probe,
 524         .remove = cros_ec_lpc_remove,
 525 };
 526 
 527 static struct platform_device cros_ec_lpc_device = {
 528         .name = DRV_NAME
 529 };
 530 
 531 static acpi_status cros_ec_lpc_parse_device(acpi_handle handle, u32 level,
 532                                             void *context, void **retval)
 533 {
 534         *(bool *)context = true;
 535         return AE_CTRL_TERMINATE;
 536 }
 537 
 538 static int __init cros_ec_lpc_init(void)
 539 {
 540         int ret;
 541         acpi_status status;
 542 
 543         status = acpi_get_devices(ACPI_DRV_NAME, cros_ec_lpc_parse_device,
 544                                   &cros_ec_lpc_acpi_device_found, NULL);
 545         if (ACPI_FAILURE(status))
 546                 pr_warn(DRV_NAME ": Looking for %s failed\n", ACPI_DRV_NAME);
 547 
 548         if (!cros_ec_lpc_acpi_device_found &&
 549             !dmi_check_system(cros_ec_lpc_dmi_table)) {
 550                 pr_err(DRV_NAME ": unsupported system.\n");
 551                 return -ENODEV;
 552         }
 553 
 554         cros_ec_lpc_mec_init(EC_HOST_CMD_REGION0,
 555                              EC_LPC_ADDR_MEMMAP + EC_MEMMAP_SIZE);
 556 
 557         /* Register the driver */
 558         ret = platform_driver_register(&cros_ec_lpc_driver);
 559         if (ret) {
 560                 pr_err(DRV_NAME ": can't register driver: %d\n", ret);
 561                 cros_ec_lpc_mec_destroy();
 562                 return ret;
 563         }
 564 
 565         if (!cros_ec_lpc_acpi_device_found) {
 566                 /* Register the device, and it'll get hooked up automatically */
 567                 ret = platform_device_register(&cros_ec_lpc_device);
 568                 if (ret) {
 569                         pr_err(DRV_NAME ": can't register device: %d\n", ret);
 570                         platform_driver_unregister(&cros_ec_lpc_driver);
 571                         cros_ec_lpc_mec_destroy();
 572                 }
 573         }
 574 
 575         return ret;
 576 }
 577 
 578 static void __exit cros_ec_lpc_exit(void)
 579 {
 580         if (!cros_ec_lpc_acpi_device_found)
 581                 platform_device_unregister(&cros_ec_lpc_device);
 582         platform_driver_unregister(&cros_ec_lpc_driver);
 583         cros_ec_lpc_mec_destroy();
 584 }
 585 
 586 module_init(cros_ec_lpc_init);
 587 module_exit(cros_ec_lpc_exit);
 588 
 589 MODULE_LICENSE("GPL");
 590 MODULE_DESCRIPTION("ChromeOS EC LPC driver");