drivers/platform/chrome/cros_ec_lpc.c

   1 /*
   2  * cros_ec_lpc - LPC access to the Chrome OS Embedded Controller
   3  *
   4  * Copyright (C) 2012-2015 Google, Inc
   5  *
   6  * This software is licensed under the terms of the GNU General Public
   7  * License version 2, as published by the Free Software Foundation, and
   8  * may be copied, distributed, and modified under those terms.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * This driver uses the Chrome OS EC byte-level message-based protocol for
  16  * communicating the keyboard state (which keys are pressed) from a keyboard EC
  17  * to the AP over some bus (such as i2c, lpc, spi).  The EC does debouncing,
  18  * but everything else (including deghosting) is done here.  The main
  19  * motivation for this is to keep the EC firmware as simple as possible, since
  20  * it cannot be easily upgraded and EC flash/IRAM space is relatively
  21  * expensive.
  22  */
  23
  24 #include <linux/acpi.h>
  25 #include <linux/dmi.h>
  26 #include <linux/delay.h>
  27 #include <linux/io.h>
  28 #include <linux/mfd/cros_ec.h>
  29 #include <linux/mfd/cros_ec_commands.h>
  30 #include <linux/mfd/cros_ec_lpc_reg.h>
  31 #include <linux/module.h>
  32 #include <linux/platform_device.h>
  33 #include <linux/printk.h>
  34
  35 #define DRV_NAME "cros_ec_lpcs"
  36 #define ACPI_DRV_NAME "GOOG0004"
  37
  38 static int ec_response_timed_out(void)
  39 {
  40         unsigned long one_second = jiffies + HZ;
  41         u8 data;
  42
  43         usleep_range(200, 300);
  44         do {
  45                 if (!(cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_CMD, 1, &data) &
  46                     EC_LPC_STATUS_BUSY_MASK))
  47                         return 0;
  48                 usleep_range(100, 200);
  49         } while (time_before(jiffies, one_second));
  50
  51         return 1;
  52 }
  53
  54 static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
  55                                 struct cros_ec_command *msg)
  56 {
  57         struct ec_host_request *request;
  58         struct ec_host_response response;
  59         u8 sum;
  60         int ret = 0;
  61         u8 *dout;
  62
  63         ret = cros_ec_prepare_tx(ec, msg);
  64
  65         /* Write buffer */
  66         cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PACKET, ret, ec->dout);
  67
  68         request = (struct ec_host_request *)ec->dout;
  69
  70         /* Here we go */
  71         sum = EC_COMMAND_PROTOCOL_3;
  72         cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_CMD, 1, &sum);
  73
  74         if (ec_response_timed_out()) {
  75                 dev_warn(ec->dev, "EC responsed timed out\n");
  76                 ret = -EIO;
  77                 goto done;
  78         }
  79
  80         /* Check result */
  81         msg->result = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_DATA, 1, &sum);
  82         ret = cros_ec_check_result(ec, msg);
  83         if (ret)
  84                 goto done;
  85
  86         /* Read back response */
  87         dout = (u8 *)&response;
  88         sum = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET, sizeof(response),
  89                                      dout);
  90
  91         msg->result = response.result;
  92
  93         if (response.data_len > msg->insize) {
  94                 dev_err(ec->dev,
  95                         "packet too long (%d bytes, expected %d)",
  96                         response.data_len, msg->insize);
  97                 ret = -EMSGSIZE;
  98                 goto done;
  99         }
 100
 101         /* Read response and process checksum */
 102         sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET +
 103                                       sizeof(response), response.data_len,
 104                                       msg->data);
 105
 106         if (sum) {
 107                 dev_err(ec->dev,
 108                         "bad packet checksum %02x\n",
 109                         response.checksum);
 110                 ret = -EBADMSG;
 111                 goto done;
 112         }
 113
 114         /* Return actual amount of data received */
 115         ret = response.data_len;
 116 done:
 117         return ret;
 118 }
 119
 120 static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
 121                                 struct cros_ec_command *msg)
 122 {
 123         struct ec_lpc_host_args args;
 124         u8 sum;
 125         int ret = 0;
 126
 127         if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
 128             msg->insize > EC_PROTO2_MAX_PARAM_SIZE) {
 129                 dev_err(ec->dev,
 130                         "invalid buffer sizes (out %d, in %d)\n",
 131                         msg->outsize, msg->insize);
 132                 return -EINVAL;
 133         }
 134
 135         /* Now actually send the command to the EC and get the result */
 136         args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
 137         args.command_version = msg->version;
 138         args.data_size = msg->outsize;
 139
 140         /* Initialize checksum */
 141         sum = msg->command + args.flags + args.command_version + args.data_size;
 142
 143         /* Copy data and update checksum */
 144         sum += cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PARAM, msg->outsize,
 145                                        msg->data);
 146
 147         /* Finalize checksum and write args */
 148         args.checksum = sum;
 149         cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
 150                                 (u8 *)&args);
 151
 152         /* Here we go */
 153         sum = msg->command;
 154         cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_CMD, 1, &sum);
 155
 156         if (ec_response_timed_out()) {
 157                 dev_warn(ec->dev, "EC responsed timed out\n");
 158                 ret = -EIO;
 159                 goto done;
 160         }
 161
 162         /* Check result */
 163         msg->result = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_DATA, 1, &sum);
 164         ret = cros_ec_check_result(ec, msg);
 165         if (ret)
 166                 goto done;
 167
 168         /* Read back args */
 169         cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
 170                                (u8 *)&args);
 171
 172         if (args.data_size > msg->insize) {
 173                 dev_err(ec->dev,
 174                         "packet too long (%d bytes, expected %d)",
 175                         args.data_size, msg->insize);
 176                 ret = -ENOSPC;
 177                 goto done;
 178         }
 179
 180         /* Start calculating response checksum */
 181         sum = msg->command + args.flags + args.command_version + args.data_size;
 182
 183         /* Read response and update checksum */
 184         sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PARAM, args.data_size,
 185                                       msg->data);
 186
 187         /* Verify checksum */
 188         if (args.checksum != sum) {
 189                 dev_err(ec->dev,
 190                         "bad packet checksum, expected %02x, got %02x\n",
 191                         args.checksum, sum);
 192                 ret = -EBADMSG;
 193                 goto done;
 194         }
 195
 196         /* Return actual amount of data received */
 197         ret = args.data_size;
 198 done:
 199         return ret;
 200 }
 201
 202 /* Returns num bytes read, or negative on error. Doesn't need locking. */
 203 static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
 204                                unsigned int bytes, void *dest)
 205 {
 206         int i = offset;
 207         char *s = dest;
 208         int cnt = 0;
 209
 210         if (offset >= EC_MEMMAP_SIZE - bytes)
 211                 return -EINVAL;
 212
 213         /* fixed length */
 214         if (bytes) {
 215                 cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + offset, bytes, s);
 216                 return bytes;
 217         }
 218
 219         /* string */
 220         for (; i < EC_MEMMAP_SIZE; i++, s++) {
 221                 cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + i, 1, s);
 222                 cnt++;
 223                 if (!*s)
 224                         break;
 225         }
 226
 227         return cnt;
 228 }
 229
 230 static void cros_ec_lpc_acpi_notify(acpi_handle device, u32 value, void *data)
 231 {
 232         struct cros_ec_device *ec_dev = data;
 233
 234         if (ec_dev->mkbp_event_supported &&
 235             cros_ec_get_next_event(ec_dev, NULL) > 0)
 236                 blocking_notifier_call_chain(&ec_dev->event_notifier, 0,
 237                                              ec_dev);
 238 }
 239
 240 static int cros_ec_lpc_probe(struct platform_device *pdev)
 241 {
 242         struct device *dev = &pdev->dev;
 243         struct acpi_device *adev;
 244         acpi_status status;
 245         struct cros_ec_device *ec_dev;
 246         u8 buf[2];
 247         int ret;
 248
 249         if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
 250                                  dev_name(dev))) {
 251                 dev_err(dev, "couldn't reserve memmap region\n");
 252                 return -EBUSY;
 253         }
 254
 255         cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2, buf);
 256         if (buf[0] != 'E' || buf[1] != 'C') {
 257                 dev_err(dev, "EC ID not detected\n");
 258                 return -ENODEV;
 259         }
 260
 261         if (!devm_request_region(dev, EC_HOST_CMD_REGION0,
 262                                  EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
 263                 dev_err(dev, "couldn't reserve region0\n");
 264                 return -EBUSY;
 265         }
 266         if (!devm_request_region(dev, EC_HOST_CMD_REGION1,
 267                                  EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
 268                 dev_err(dev, "couldn't reserve region1\n");
 269                 return -EBUSY;
 270         }
 271
 272         ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
 273         if (!ec_dev)
 274                 return -ENOMEM;
 275
 276         platform_set_drvdata(pdev, ec_dev);
 277         ec_dev->dev = dev;
 278         ec_dev->phys_name = dev_name(dev);
 279         ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
 280         ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
 281         ec_dev->cmd_readmem = cros_ec_lpc_readmem;
 282         ec_dev->din_size = sizeof(struct ec_host_response) +
 283                            sizeof(struct ec_response_get_protocol_info);
 284         ec_dev->dout_size = sizeof(struct ec_host_request);
 285
 286         ret = cros_ec_register(ec_dev);
 287         if (ret) {
 288                 dev_err(dev, "couldn't register ec_dev (%d)\n", ret);
 289                 return ret;
 290         }
 291
 292         /*
 293          * Connect a notify handler to process MKBP messages if we have a
 294          * companion ACPI device.
 295          */
 296         adev = ACPI_COMPANION(dev);
 297         if (adev) {
 298                 status = acpi_install_notify_handler(adev->handle,
 299                                                      ACPI_ALL_NOTIFY,
 300                                                      cros_ec_lpc_acpi_notify,
 301                                                      ec_dev);
 302                 if (ACPI_FAILURE(status))
 303                         dev_warn(dev, "Failed to register notifier %08x\n",
 304                                  status);
 305         }
 306
 307         return 0;
 308 }
 309
 310 static int cros_ec_lpc_remove(struct platform_device *pdev)
 311 {
 312         struct cros_ec_device *ec_dev;
 313         struct acpi_device *adev;
 314
 315         adev = ACPI_COMPANION(&pdev->dev);
 316         if (adev)
 317                 acpi_remove_notify_handler(adev->handle, ACPI_ALL_NOTIFY,
 318                                            cros_ec_lpc_acpi_notify);
 319
 320         ec_dev = platform_get_drvdata(pdev);
 321         cros_ec_remove(ec_dev);
 322
 323         return 0;
 324 }
 325
 326 static const struct acpi_device_id cros_ec_lpc_acpi_device_ids[] = {
 327         { ACPI_DRV_NAME, 0 },
 328         { }
 329 };
 330 MODULE_DEVICE_TABLE(acpi, cros_ec_lpc_acpi_device_ids);
 331
 332 static struct dmi_system_id cros_ec_lpc_dmi_table[] __initdata = {
 333         {
 334                 /*
 335                  * Today all Chromebooks/boxes ship with Google_* as version and
 336                  * coreboot as bios vendor. No other systems with this
 337                  * combination are known to date.
 338                  */
 339                 .matches = {
 340                         DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
 341                         DMI_MATCH(DMI_BIOS_VERSION, "Google_"),
 342                 },
 343         },
 344         {
 345                 /* x86-link, the Chromebook Pixel. */
 346                 .matches = {
 347                         DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 348                         DMI_MATCH(DMI_PRODUCT_NAME, "Link"),
 349                 },
 350         },
 351         {
 352                 /* x86-samus, the Chromebook Pixel 2. */
 353                 .matches = {
 354                         DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 355                         DMI_MATCH(DMI_PRODUCT_NAME, "Samus"),
 356                 },
 357         },
 358         {
 359                 /* x86-peppy, the Acer C720 Chromebook. */
 360                 .matches = {
 361                         DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
 362                         DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"),
 363                 },
 364         },
 365         { /* sentinel */ }
 366 };
 367 MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table);
 368
 369 #ifdef CONFIG_PM_SLEEP
 370 static int cros_ec_lpc_suspend(struct device *dev)
 371 {
 372         struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
 373
 374         return cros_ec_suspend(ec_dev);
 375 }
 376
 377 static int cros_ec_lpc_resume(struct device *dev)
 378 {
 379         struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
 380
 381         return cros_ec_resume(ec_dev);
 382 }
 383 #endif
 384
 385 const struct dev_pm_ops cros_ec_lpc_pm_ops = {
 386         SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_lpc_suspend, cros_ec_lpc_resume)
 387 };
 388
 389 static struct platform_driver cros_ec_lpc_driver = {
 390         .driver = {
 391                 .name = DRV_NAME,
 392                 .acpi_match_table = cros_ec_lpc_acpi_device_ids,
 393                 .pm = &cros_ec_lpc_pm_ops,
 394         },
 395         .probe = cros_ec_lpc_probe,
 396         .remove = cros_ec_lpc_remove,
 397 };
 398
 399 static int __init cros_ec_lpc_init(void)
 400 {
 401         int ret;
 402
 403         if (!dmi_check_system(cros_ec_lpc_dmi_table)) {
 404                 pr_err(DRV_NAME ": unsupported system.\n");
 405                 return -ENODEV;
 406         }
 407
 408         cros_ec_lpc_reg_init();
 409
 410         /* Register the driver */
 411         ret = platform_driver_register(&cros_ec_lpc_driver);
 412         if (ret) {
 413                 pr_err(DRV_NAME ": can't register driver: %d\n", ret);
 414                 cros_ec_lpc_reg_destroy();
 415                 return ret;
 416         }
 417
 418         return 0;
 419 }
 420
 421 static void __exit cros_ec_lpc_exit(void)
 422 {
 423         platform_driver_unregister(&cros_ec_lpc_driver);
 424         cros_ec_lpc_reg_destroy();
 425 }
 426
 427 module_init(cros_ec_lpc_init);
 428 module_exit(cros_ec_lpc_exit);
 429
 430 MODULE_LICENSE("GPL");
 431 MODULE_DESCRIPTION("ChromeOS EC LPC driver");