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/dmi.h>
  25 #include <linux/delay.h>
  26 #include <linux/io.h>
  27 #include <linux/mfd/cros_ec.h>
  28 #include <linux/mfd/cros_ec_commands.h>
  29 #include <linux/module.h>
  30 #include <linux/platform_device.h>
  31 #include <linux/printk.h>
  32
  33 #define DRV_NAME "cros_ec_lpc"
  34
  35 static int ec_response_timed_out(void)
  36 {
  37         unsigned long one_second = jiffies + HZ;
  38
  39         usleep_range(200, 300);
  40         do {
  41                 if (!(inb(EC_LPC_ADDR_HOST_CMD) & EC_LPC_STATUS_BUSY_MASK))
  42                         return 0;
  43                 usleep_range(100, 200);
  44         } while (time_before(jiffies, one_second));
  45
  46         return 1;
  47 }
  48
  49 static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
  50                                 struct cros_ec_command *msg)
  51 {
  52         struct ec_host_request *request;
  53         struct ec_host_response response;
  54         u8 sum = 0;
  55         int i;
  56         int ret = 0;
  57         u8 *dout;
  58
  59         ret = cros_ec_prepare_tx(ec, msg);
  60
  61         /* Write buffer */
  62         for (i = 0; i < ret; i++)
  63                 outb(ec->dout[i], EC_LPC_ADDR_HOST_PACKET + i);
  64
  65         request = (struct ec_host_request *)ec->dout;
  66
  67         /* Here we go */
  68         outb(EC_COMMAND_PROTOCOL_3, EC_LPC_ADDR_HOST_CMD);
  69
  70         if (ec_response_timed_out()) {
  71                 dev_warn(ec->dev, "EC responsed timed out\n");
  72                 ret = -EIO;
  73                 goto done;
  74         }
  75
  76         /* Check result */
  77         msg->result = inb(EC_LPC_ADDR_HOST_DATA);
  78         ret = cros_ec_check_result(ec, msg);
  79         if (ret)
  80                 goto done;
  81
  82         /* Read back response */
  83         dout = (u8 *)&response;
  84         for (i = 0; i < sizeof(response); i++) {
  85                 dout[i] = inb(EC_LPC_ADDR_HOST_PACKET + i);
  86                 sum += dout[i];
  87         }
  88
  89         msg->result = response.result;
  90
  91         if (response.data_len > msg->insize) {
  92                 dev_err(ec->dev,
  93                         "packet too long (%d bytes, expected %d)",
  94                         response.data_len, msg->insize);
  95                 ret = -EMSGSIZE;
  96                 goto done;
  97         }
  98
  99         /* Read response and process checksum */
 100         for (i = 0; i < response.data_len; i++) {
 101                 msg->data[i] =
 102                         inb(EC_LPC_ADDR_HOST_PACKET + sizeof(response) + i);
 103                 sum += msg->data[i];
 104         }
 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         int csum;
 125         int i;
 126         int ret = 0;
 127
 128         if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
 129             msg->insize > EC_PROTO2_MAX_PARAM_SIZE) {
 130                 dev_err(ec->dev,
 131                         "invalid buffer sizes (out %d, in %d)\n",
 132                         msg->outsize, msg->insize);
 133                 return -EINVAL;
 134         }
 135
 136         /* Now actually send the command to the EC and get the result */
 137         args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
 138         args.command_version = msg->version;
 139         args.data_size = msg->outsize;
 140
 141         /* Initialize checksum */
 142         csum = msg->command + args.flags +
 143                 args.command_version + args.data_size;
 144
 145         /* Copy data and update checksum */
 146         for (i = 0; i < msg->outsize; i++) {
 147                 outb(msg->data[i], EC_LPC_ADDR_HOST_PARAM + i);
 148                 csum += msg->data[i];
 149         }
 150
 151         /* Finalize checksum and write args */
 152         args.checksum = csum & 0xFF;
 153         outb(args.flags, EC_LPC_ADDR_HOST_ARGS);
 154         outb(args.command_version, EC_LPC_ADDR_HOST_ARGS + 1);
 155         outb(args.data_size, EC_LPC_ADDR_HOST_ARGS + 2);
 156         outb(args.checksum, EC_LPC_ADDR_HOST_ARGS + 3);
 157
 158         /* Here we go */
 159         outb(msg->command, EC_LPC_ADDR_HOST_CMD);
 160
 161         if (ec_response_timed_out()) {
 162                 dev_warn(ec->dev, "EC responsed timed out\n");
 163                 ret = -EIO;
 164                 goto done;
 165         }
 166
 167         /* Check result */
 168         msg->result = inb(EC_LPC_ADDR_HOST_DATA);
 169         ret = cros_ec_check_result(ec, msg);
 170         if (ret)
 171                 goto done;
 172
 173         /* Read back args */
 174         args.flags = inb(EC_LPC_ADDR_HOST_ARGS);
 175         args.command_version = inb(EC_LPC_ADDR_HOST_ARGS + 1);
 176         args.data_size = inb(EC_LPC_ADDR_HOST_ARGS + 2);
 177         args.checksum = inb(EC_LPC_ADDR_HOST_ARGS + 3);
 178
 179         if (args.data_size > msg->insize) {
 180                 dev_err(ec->dev,
 181                         "packet too long (%d bytes, expected %d)",
 182                         args.data_size, msg->insize);
 183                 ret = -ENOSPC;
 184                 goto done;
 185         }
 186
 187         /* Start calculating response checksum */
 188         csum = msg->command + args.flags +
 189                 args.command_version + args.data_size;
 190
 191         /* Read response and update checksum */
 192         for (i = 0; i < args.data_size; i++) {
 193                 msg->data[i] = inb(EC_LPC_ADDR_HOST_PARAM + i);
 194                 csum += msg->data[i];
 195         }
 196
 197         /* Verify checksum */
 198         if (args.checksum != (csum & 0xFF)) {
 199                 dev_err(ec->dev,
 200                         "bad packet checksum, expected %02x, got %02x\n",
 201                         args.checksum, csum & 0xFF);
 202                 ret = -EBADMSG;
 203                 goto done;
 204         }
 205
 206         /* Return actual amount of data received */
 207         ret = args.data_size;
 208 done:
 209         return ret;
 210 }
 211
 212 /* Returns num bytes read, or negative on error. Doesn't need locking. */
 213 static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
 214                                unsigned int bytes, void *dest)
 215 {
 216         int i = offset;
 217         char *s = dest;
 218         int cnt = 0;
 219
 220         if (offset >= EC_MEMMAP_SIZE - bytes)
 221                 return -EINVAL;
 222
 223         /* fixed length */
 224         if (bytes) {
 225                 for (; cnt < bytes; i++, s++, cnt++)
 226                         *s = inb(EC_LPC_ADDR_MEMMAP + i);
 227                 return cnt;
 228         }
 229
 230         /* string */
 231         for (; i < EC_MEMMAP_SIZE; i++, s++) {
 232                 *s = inb(EC_LPC_ADDR_MEMMAP + i);
 233                 cnt++;
 234                 if (!*s)
 235                         break;
 236         }
 237
 238         return cnt;
 239 }
 240
 241 static int cros_ec_lpc_probe(struct platform_device *pdev)
 242 {
 243         struct device *dev = &pdev->dev;
 244         struct cros_ec_device *ec_dev;
 245         int ret;
 246
 247         if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
 248                                  dev_name(dev))) {
 249                 dev_err(dev, "couldn't reserve memmap region\n");
 250                 return -EBUSY;
 251         }
 252
 253         if ((inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID) != 'E') ||
 254             (inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID + 1) != 'C')) {
 255                 dev_err(dev, "EC ID not detected\n");
 256                 return -ENODEV;
 257         }
 258
 259         if (!devm_request_region(dev, EC_HOST_CMD_REGION0,
 260                                  EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
 261                 dev_err(dev, "couldn't reserve region0\n");
 262                 return -EBUSY;
 263         }
 264         if (!devm_request_region(dev, EC_HOST_CMD_REGION1,
 265                                  EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
 266                 dev_err(dev, "couldn't reserve region1\n");
 267                 return -EBUSY;
 268         }
 269
 270         ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
 271         if (!ec_dev)
 272                 return -ENOMEM;
 273
 274         platform_set_drvdata(pdev, ec_dev);
 275         ec_dev->dev = dev;
 276         ec_dev->phys_name = dev_name(dev);
 277         ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
 278         ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
 279         ec_dev->cmd_readmem = cros_ec_lpc_readmem;
 280         ec_dev->din_size = sizeof(struct ec_host_response) +
 281                            sizeof(struct ec_response_get_protocol_info);
 282         ec_dev->dout_size = sizeof(struct ec_host_request);
 283
 284         ret = cros_ec_register(ec_dev);
 285         if (ret) {
 286                 dev_err(dev, "couldn't register ec_dev (%d)\n", ret);
 287                 return ret;
 288         }
 289
 290         return 0;
 291 }
 292
 293 static int cros_ec_lpc_remove(struct platform_device *pdev)
 294 {
 295         struct cros_ec_device *ec_dev;
 296
 297         ec_dev = platform_get_drvdata(pdev);
 298         cros_ec_remove(ec_dev);
 299
 300         return 0;
 301 }
 302
 303 static struct dmi_system_id cros_ec_lpc_dmi_table[] __initdata = {
 304         {
 305                 /*
 306                  * Today all Chromebooks/boxes ship with Google_* as version and
 307                  * coreboot as bios vendor. No other systems with this
 308                  * combination are known to date.
 309                  */
 310                 .matches = {
 311                         DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
 312                         DMI_MATCH(DMI_BIOS_VERSION, "Google_"),
 313                 },
 314         },
 315         {
 316                 /* x86-link, the Chromebook Pixel. */
 317                 .matches = {
 318                         DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 319                         DMI_MATCH(DMI_PRODUCT_NAME, "Link"),
 320                 },
 321         },
 322         {
 323                 /* x86-samus, the Chromebook Pixel 2. */
 324                 .matches = {
 325                         DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 326                         DMI_MATCH(DMI_PRODUCT_NAME, "Samus"),
 327                 },
 328         },
 329         {
 330                 /* x86-peppy, the Acer C720 Chromebook. */
 331                 .matches = {
 332                         DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
 333                         DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"),
 334                 },
 335         },
 336         { /* sentinel */ }
 337 };
 338 MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table);
 339
 340 static struct platform_driver cros_ec_lpc_driver = {
 341         .driver = {
 342                 .name = DRV_NAME,
 343         },
 344         .probe = cros_ec_lpc_probe,
 345         .remove = cros_ec_lpc_remove,
 346 };
 347
 348 static struct platform_device cros_ec_lpc_device = {
 349         .name = DRV_NAME
 350 };
 351
 352 static int __init cros_ec_lpc_init(void)
 353 {
 354         int ret;
 355
 356         if (!dmi_check_system(cros_ec_lpc_dmi_table)) {
 357                 pr_err(DRV_NAME ": unsupported system.\n");
 358                 return -ENODEV;
 359         }
 360
 361         /* Register the driver */
 362         ret = platform_driver_register(&cros_ec_lpc_driver);
 363         if (ret) {
 364                 pr_err(DRV_NAME ": can't register driver: %d\n", ret);
 365                 return ret;
 366         }
 367
 368         /* Register the device, and it'll get hooked up automatically */
 369         ret = platform_device_register(&cros_ec_lpc_device);
 370         if (ret) {
 371                 pr_err(DRV_NAME ": can't register device: %d\n", ret);
 372                 platform_driver_unregister(&cros_ec_lpc_driver);
 373                 return ret;
 374         }
 375
 376         return 0;
 377 }
 378
 379 static void __exit cros_ec_lpc_exit(void)
 380 {
 381         platform_device_unregister(&cros_ec_lpc_device);
 382         platform_driver_unregister(&cros_ec_lpc_driver);
 383 }
 384
 385 module_init(cros_ec_lpc_init);
 386 module_exit(cros_ec_lpc_exit);
 387
 388 MODULE_LICENSE("GPL");
 389 MODULE_DESCRIPTION("ChromeOS EC LPC driver");