drivers/platform/chrome/cros_ec_lpc.c

   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.h"
  27 #include "cros_ec_lpc_mec.h"
  28
  29 #define DRV_NAME "cros_ec_lpcs"
  30 #define ACPI_DRV_NAME "GOOG0004"
  31
  32 /* True if ACPI device is present */
  33 static bool cros_ec_lpc_acpi_device_found;
  34
  35 /**
  36  * struct lpc_driver_ops - LPC driver operations
  37  * @read: Copy length bytes from EC address offset into buffer dest. Returns
  38  *        the 8-bit checksum of all bytes read.
  39  * @write: Copy length bytes from buffer msg into EC address offset. Returns
  40  *         the 8-bit checksum of all bytes written.
  41  */
  42 struct lpc_driver_ops {
  43         u8 (*read)(unsigned int offset, unsigned int length, u8 *dest);
  44         u8 (*write)(unsigned int offset, unsigned int length, const u8 *msg);
  45 };
  46
  47 static struct lpc_driver_ops cros_ec_lpc_ops = { };
  48
  49 /*
  50  * A generic instance of the read function of struct lpc_driver_ops, used for
  51  * the LPC EC.
  52  */
  53 static u8 cros_ec_lpc_read_bytes(unsigned int offset, unsigned int length,
  54                                  u8 *dest)
  55 {
  56         int sum = 0;
  57         int i;
  58
  59         for (i = 0; i < length; ++i) {
  60                 dest[i] = inb(offset + i);
  61                 sum += dest[i];
  62         }
  63
  64         /* Return checksum of all bytes read */
  65         return sum;
  66 }
  67
  68 /*
  69  * A generic instance of the write function of struct lpc_driver_ops, used for
  70  * the LPC EC.
  71  */
  72 static u8 cros_ec_lpc_write_bytes(unsigned int offset, unsigned int length,
  73                                   const u8 *msg)
  74 {
  75         int sum = 0;
  76         int i;
  77
  78         for (i = 0; i < length; ++i) {
  79                 outb(msg[i], offset + i);
  80                 sum += msg[i];
  81         }
  82
  83         /* Return checksum of all bytes written */
  84         return sum;
  85 }
  86
  87 /*
  88  * An instance of the read function of struct lpc_driver_ops, used for the
  89  * MEC variant of LPC EC.
  90  */
  91 static u8 cros_ec_lpc_mec_read_bytes(unsigned int offset, unsigned int length,
  92                                      u8 *dest)
  93 {
  94         int in_range = cros_ec_lpc_mec_in_range(offset, length);
  95
  96         if (in_range < 0)
  97                 return 0;
  98
  99         return in_range ?
 100                 cros_ec_lpc_io_bytes_mec(MEC_IO_READ,
 101                                          offset - EC_HOST_CMD_REGION0,
 102                                          length, dest) :
 103                 cros_ec_lpc_read_bytes(offset, length, dest);
 104 }
 105
 106 /*
 107  * An instance of the write function of struct lpc_driver_ops, used for the
 108  * MEC variant of LPC EC.
 109  */
 110 static u8 cros_ec_lpc_mec_write_bytes(unsigned int offset, unsigned int length,
 111                                       const u8 *msg)
 112 {
 113         int in_range = cros_ec_lpc_mec_in_range(offset, length);
 114
 115         if (in_range < 0)
 116                 return 0;
 117
 118         return in_range ?
 119                 cros_ec_lpc_io_bytes_mec(MEC_IO_WRITE,
 120                                          offset - EC_HOST_CMD_REGION0,
 121                                          length, (u8 *)msg) :
 122                 cros_ec_lpc_write_bytes(offset, length, msg);
 123 }
 124
 125 static int ec_response_timed_out(void)
 126 {
 127         unsigned long one_second = jiffies + HZ;
 128         u8 data;
 129
 130         usleep_range(200, 300);
 131         do {
 132                 if (!(cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_CMD, 1, &data) &
 133                     EC_LPC_STATUS_BUSY_MASK))
 134                         return 0;
 135                 usleep_range(100, 200);
 136         } while (time_before(jiffies, one_second));
 137
 138         return 1;
 139 }
 140
 141 static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
 142                                 struct cros_ec_command *msg)
 143 {
 144         struct ec_host_response response;
 145         u8 sum;
 146         int ret = 0;
 147         u8 *dout;
 148
 149         ret = cros_ec_prepare_tx(ec, msg);
 150
 151         /* Write buffer */
 152         cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_PACKET, ret, ec->dout);
 153
 154         /* Here we go */
 155         sum = EC_COMMAND_PROTOCOL_3;
 156         cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_CMD, 1, &sum);
 157
 158         if (ec_response_timed_out()) {
 159                 dev_warn(ec->dev, "EC responsed timed out\n");
 160                 ret = -EIO;
 161                 goto done;
 162         }
 163
 164         /* Check result */
 165         msg->result = cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_DATA, 1, &sum);
 166         ret = cros_ec_check_result(ec, msg);
 167         if (ret)
 168                 goto done;
 169
 170         /* Read back response */
 171         dout = (u8 *)&response;
 172         sum = cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_PACKET, sizeof(response),
 173                                    dout);
 174
 175         msg->result = response.result;
 176
 177         if (response.data_len > msg->insize) {
 178                 dev_err(ec->dev,
 179                         "packet too long (%d bytes, expected %d)",
 180                         response.data_len, msg->insize);
 181                 ret = -EMSGSIZE;
 182                 goto done;
 183         }
 184
 185         /* Read response and process checksum */
 186         sum += cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_PACKET +
 187                                     sizeof(response), response.data_len,
 188                                     msg->data);
 189
 190         if (sum) {
 191                 dev_err(ec->dev,
 192                         "bad packet checksum %02x\n",
 193                         response.checksum);
 194                 ret = -EBADMSG;
 195                 goto done;
 196         }
 197
 198         /* Return actual amount of data received */
 199         ret = response.data_len;
 200 done:
 201         return ret;
 202 }
 203
 204 static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
 205                                 struct cros_ec_command *msg)
 206 {
 207         struct ec_lpc_host_args args;
 208         u8 sum;
 209         int ret = 0;
 210
 211         if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
 212             msg->insize > EC_PROTO2_MAX_PARAM_SIZE) {
 213                 dev_err(ec->dev,
 214                         "invalid buffer sizes (out %d, in %d)\n",
 215                         msg->outsize, msg->insize);
 216                 return -EINVAL;
 217         }
 218
 219         /* Now actually send the command to the EC and get the result */
 220         args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
 221         args.command_version = msg->version;
 222         args.data_size = msg->outsize;
 223
 224         /* Initialize checksum */
 225         sum = msg->command + args.flags + args.command_version + args.data_size;
 226
 227         /* Copy data and update checksum */
 228         sum += cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_PARAM, msg->outsize,
 229                                      msg->data);
 230
 231         /* Finalize checksum and write args */
 232         args.checksum = sum;
 233         cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
 234                               (u8 *)&args);
 235
 236         /* Here we go */
 237         sum = msg->command;
 238         cros_ec_lpc_ops.write(EC_LPC_ADDR_HOST_CMD, 1, &sum);
 239
 240         if (ec_response_timed_out()) {
 241                 dev_warn(ec->dev, "EC responsed timed out\n");
 242                 ret = -EIO;
 243                 goto done;
 244         }
 245
 246         /* Check result */
 247         msg->result = cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_DATA, 1, &sum);
 248         ret = cros_ec_check_result(ec, msg);
 249         if (ret)
 250                 goto done;
 251
 252         /* Read back args */
 253         cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_ARGS, sizeof(args), (u8 *)&args);
 254
 255         if (args.data_size > msg->insize) {
 256                 dev_err(ec->dev,
 257                         "packet too long (%d bytes, expected %d)",
 258                         args.data_size, msg->insize);
 259                 ret = -ENOSPC;
 260                 goto done;
 261         }
 262
 263         /* Start calculating response checksum */
 264         sum = msg->command + args.flags + args.command_version + args.data_size;
 265
 266         /* Read response and update checksum */
 267         sum += cros_ec_lpc_ops.read(EC_LPC_ADDR_HOST_PARAM, args.data_size,
 268                                     msg->data);
 269
 270         /* Verify checksum */
 271         if (args.checksum != sum) {
 272                 dev_err(ec->dev,
 273                         "bad packet checksum, expected %02x, got %02x\n",
 274                         args.checksum, sum);
 275                 ret = -EBADMSG;
 276                 goto done;
 277         }
 278
 279         /* Return actual amount of data received */
 280         ret = args.data_size;
 281 done:
 282         return ret;
 283 }
 284
 285 /* Returns num bytes read, or negative on error. Doesn't need locking. */
 286 static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
 287                                unsigned int bytes, void *dest)
 288 {
 289         int i = offset;
 290         char *s = dest;
 291         int cnt = 0;
 292
 293         if (offset >= EC_MEMMAP_SIZE - bytes)
 294                 return -EINVAL;
 295
 296         /* fixed length */
 297         if (bytes) {
 298                 cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + offset, bytes, s);
 299                 return bytes;
 300         }
 301
 302         /* string */
 303         for (; i < EC_MEMMAP_SIZE; i++, s++) {
 304                 cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + i, 1, s);
 305                 cnt++;
 306                 if (!*s)
 307                         break;
 308         }
 309
 310         return cnt;
 311 }
 312
 313 static void cros_ec_lpc_acpi_notify(acpi_handle device, u32 value, void *data)
 314 {
 315         struct cros_ec_device *ec_dev = data;
 316         bool ec_has_more_events;
 317         int ret;
 318
 319         ec_dev->last_event_time = cros_ec_get_time_ns();
 320
 321         if (ec_dev->mkbp_event_supported)
 322                 do {
 323                         ret = cros_ec_get_next_event(ec_dev, NULL,
 324                                                      &ec_has_more_events);
 325                         if (ret > 0)
 326                                 blocking_notifier_call_chain(
 327                                                 &ec_dev->event_notifier, 0,
 328                                                 ec_dev);
 329                 } while (ec_has_more_events);
 330
 331         if (value == ACPI_NOTIFY_DEVICE_WAKE)
 332                 pm_system_wakeup();
 333 }
 334
 335 static int cros_ec_lpc_probe(struct platform_device *pdev)
 336 {
 337         struct device *dev = &pdev->dev;
 338         struct acpi_device *adev;
 339         acpi_status status;
 340         struct cros_ec_device *ec_dev;
 341         u8 buf[2];
 342         int irq, ret;
 343
 344         if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
 345                                  dev_name(dev))) {
 346                 dev_err(dev, "couldn't reserve memmap region\n");
 347                 return -EBUSY;
 348         }
 349
 350         /*
 351          * Read the mapped ID twice, the first one is assuming the
 352          * EC is a Microchip Embedded Controller (MEC) variant, if the
 353          * protocol fails, fallback to the non MEC variant and try to
 354          * read again the ID.
 355          */
 356         cros_ec_lpc_ops.read = cros_ec_lpc_mec_read_bytes;
 357         cros_ec_lpc_ops.write = cros_ec_lpc_mec_write_bytes;
 358         cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2, buf);
 359         if (buf[0] != 'E' || buf[1] != 'C') {
 360                 /* Re-assign read/write operations for the non MEC variant */
 361                 cros_ec_lpc_ops.read = cros_ec_lpc_read_bytes;
 362                 cros_ec_lpc_ops.write = cros_ec_lpc_write_bytes;
 363                 cros_ec_lpc_ops.read(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2,
 364                                      buf);
 365                 if (buf[0] != 'E' || buf[1] != 'C') {
 366                         dev_err(dev, "EC ID not detected\n");
 367                         return -ENODEV;
 368                 }
 369         }
 370
 371         if (!devm_request_region(dev, EC_HOST_CMD_REGION0,
 372                                  EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
 373                 dev_err(dev, "couldn't reserve region0\n");
 374                 return -EBUSY;
 375         }
 376         if (!devm_request_region(dev, EC_HOST_CMD_REGION1,
 377                                  EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
 378                 dev_err(dev, "couldn't reserve region1\n");
 379                 return -EBUSY;
 380         }
 381
 382         ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
 383         if (!ec_dev)
 384                 return -ENOMEM;
 385
 386         platform_set_drvdata(pdev, ec_dev);
 387         ec_dev->dev = dev;
 388         ec_dev->phys_name = dev_name(dev);
 389         ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
 390         ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
 391         ec_dev->cmd_readmem = cros_ec_lpc_readmem;
 392         ec_dev->din_size = sizeof(struct ec_host_response) +
 393                            sizeof(struct ec_response_get_protocol_info);
 394         ec_dev->dout_size = sizeof(struct ec_host_request);
 395
 396         /*
 397          * Some boards do not have an IRQ allotted for cros_ec_lpc,
 398          * which makes ENXIO an expected (and safe) scenario.
 399          */
 400         irq = platform_get_irq_optional(pdev, 0);
 401         if (irq > 0)
 402                 ec_dev->irq = irq;
 403         else if (irq != -ENXIO) {
 404                 dev_err(dev, "couldn't retrieve IRQ number (%d)\n", irq);
 405                 return irq;
 406         }
 407
 408         ret = cros_ec_register(ec_dev);
 409         if (ret) {
 410                 dev_err(dev, "couldn't register ec_dev (%d)\n", ret);
 411                 return ret;
 412         }
 413
 414         /*
 415          * Connect a notify handler to process MKBP messages if we have a
 416          * companion ACPI device.
 417          */
 418         adev = ACPI_COMPANION(dev);
 419         if (adev) {
 420                 status = acpi_install_notify_handler(adev->handle,
 421                                                      ACPI_ALL_NOTIFY,
 422                                                      cros_ec_lpc_acpi_notify,
 423                                                      ec_dev);
 424                 if (ACPI_FAILURE(status))
 425                         dev_warn(dev, "Failed to register notifier %08x\n",
 426                                  status);
 427         }
 428
 429         return 0;
 430 }
 431
 432 static int cros_ec_lpc_remove(struct platform_device *pdev)
 433 {
 434         struct cros_ec_device *ec_dev = platform_get_drvdata(pdev);
 435         struct acpi_device *adev;
 436
 437         adev = ACPI_COMPANION(&pdev->dev);
 438         if (adev)
 439                 acpi_remove_notify_handler(adev->handle, ACPI_ALL_NOTIFY,
 440                                            cros_ec_lpc_acpi_notify);
 441
 442         return cros_ec_unregister(ec_dev);
 443 }
 444
 445 static const struct acpi_device_id cros_ec_lpc_acpi_device_ids[] = {
 446         { ACPI_DRV_NAME, 0 },
 447         { }
 448 };
 449 MODULE_DEVICE_TABLE(acpi, cros_ec_lpc_acpi_device_ids);
 450
 451 static const struct dmi_system_id cros_ec_lpc_dmi_table[] __initconst = {
 452         {
 453                 /*
 454                  * Today all Chromebooks/boxes ship with Google_* as version and
 455                  * coreboot as bios vendor. No other systems with this
 456                  * combination are known to date.
 457                  */
 458                 .matches = {
 459                         DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
 460                         DMI_MATCH(DMI_BIOS_VERSION, "Google_"),
 461                 },
 462         },
 463         {
 464                 /*
 465                  * If the box is running custom coreboot firmware then the
 466                  * DMI BIOS version string will not be matched by "Google_",
 467                  * but the system vendor string will still be matched by
 468                  * "GOOGLE".
 469                  */
 470                 .matches = {
 471                         DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
 472                         DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 473                 },
 474         },
 475         {
 476                 /* x86-link, the Chromebook Pixel. */
 477                 .matches = {
 478                         DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 479                         DMI_MATCH(DMI_PRODUCT_NAME, "Link"),
 480                 },
 481         },
 482         {
 483                 /* x86-samus, the Chromebook Pixel 2. */
 484                 .matches = {
 485                         DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 486                         DMI_MATCH(DMI_PRODUCT_NAME, "Samus"),
 487                 },
 488         },
 489         {
 490                 /* x86-peppy, the Acer C720 Chromebook. */
 491                 .matches = {
 492                         DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
 493                         DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"),
 494                 },
 495         },
 496         {
 497                 /* x86-glimmer, the Lenovo Thinkpad Yoga 11e. */
 498                 .matches = {
 499                         DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 500                         DMI_MATCH(DMI_PRODUCT_NAME, "Glimmer"),
 501                 },
 502         },
 503         { /* sentinel */ }
 504 };
 505 MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table);
 506
 507 #ifdef CONFIG_PM_SLEEP
 508 static int cros_ec_lpc_suspend(struct device *dev)
 509 {
 510         struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
 511
 512         return cros_ec_suspend(ec_dev);
 513 }
 514
 515 static int cros_ec_lpc_resume(struct device *dev)
 516 {
 517         struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
 518
 519         return cros_ec_resume(ec_dev);
 520 }
 521 #endif
 522
 523 static const struct dev_pm_ops cros_ec_lpc_pm_ops = {
 524         SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_lpc_suspend, cros_ec_lpc_resume)
 525 };
 526
 527 static struct platform_driver cros_ec_lpc_driver = {
 528         .driver = {
 529                 .name = DRV_NAME,
 530                 .acpi_match_table = cros_ec_lpc_acpi_device_ids,
 531                 .pm = &cros_ec_lpc_pm_ops,
 532         },
 533         .probe = cros_ec_lpc_probe,
 534         .remove = cros_ec_lpc_remove,
 535 };
 536
 537 static struct platform_device cros_ec_lpc_device = {
 538         .name = DRV_NAME
 539 };
 540
 541 static acpi_status cros_ec_lpc_parse_device(acpi_handle handle, u32 level,
 542                                             void *context, void **retval)
 543 {
 544         *(bool *)context = true;
 545         return AE_CTRL_TERMINATE;
 546 }
 547
 548 static int __init cros_ec_lpc_init(void)
 549 {
 550         int ret;
 551         acpi_status status;
 552
 553         status = acpi_get_devices(ACPI_DRV_NAME, cros_ec_lpc_parse_device,
 554                                   &cros_ec_lpc_acpi_device_found, NULL);
 555         if (ACPI_FAILURE(status))
 556                 pr_warn(DRV_NAME ": Looking for %s failed\n", ACPI_DRV_NAME);
 557
 558         if (!cros_ec_lpc_acpi_device_found &&
 559             !dmi_check_system(cros_ec_lpc_dmi_table)) {
 560                 pr_err(DRV_NAME ": unsupported system.\n");
 561                 return -ENODEV;
 562         }
 563
 564         cros_ec_lpc_mec_init(EC_HOST_CMD_REGION0,
 565                              EC_LPC_ADDR_MEMMAP + EC_MEMMAP_SIZE);
 566
 567         /* Register the driver */
 568         ret = platform_driver_register(&cros_ec_lpc_driver);
 569         if (ret) {
 570                 pr_err(DRV_NAME ": can't register driver: %d\n", ret);
 571                 cros_ec_lpc_mec_destroy();
 572                 return ret;
 573         }
 574
 575         if (!cros_ec_lpc_acpi_device_found) {
 576                 /* Register the device, and it'll get hooked up automatically */
 577                 ret = platform_device_register(&cros_ec_lpc_device);
 578                 if (ret) {
 579                         pr_err(DRV_NAME ": can't register device: %d\n", ret);
 580                         platform_driver_unregister(&cros_ec_lpc_driver);
 581                         cros_ec_lpc_mec_destroy();
 582                 }
 583         }
 584
 585         return ret;
 586 }
 587
 588 static void __exit cros_ec_lpc_exit(void)
 589 {
 590         if (!cros_ec_lpc_acpi_device_found)
 591                 platform_device_unregister(&cros_ec_lpc_device);
 592         platform_driver_unregister(&cros_ec_lpc_driver);
 593         cros_ec_lpc_mec_destroy();
 594 }
 595
 596 module_init(cros_ec_lpc_init);
 597 module_exit(cros_ec_lpc_exit);
 598
 599 MODULE_LICENSE("GPL");
 600 MODULE_DESCRIPTION("ChromeOS EC LPC driver");