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_cmd_xfer_lpc(struct cros_ec_device *ec,
  50                                 struct cros_ec_command *msg)
  51 {
  52         struct ec_lpc_host_args args;
  53         int csum;
  54         int i;
  55         int ret = 0;
  56
  57         if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
  58             msg->insize > EC_PROTO2_MAX_PARAM_SIZE) {
  59                 dev_err(ec->dev,
  60                         "invalid buffer sizes (out %d, in %d)\n",
  61                         msg->outsize, msg->insize);
  62                 return -EINVAL;
  63         }
  64
  65         /* Now actually send the command to the EC and get the result */
  66         args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
  67         args.command_version = msg->version;
  68         args.data_size = msg->outsize;
  69
  70         /* Initialize checksum */
  71         csum = msg->command + args.flags +
  72                 args.command_version + args.data_size;
  73
  74         /* Copy data and update checksum */
  75         for (i = 0; i < msg->outsize; i++) {
  76                 outb(msg->outdata[i], EC_LPC_ADDR_HOST_PARAM + i);
  77                 csum += msg->outdata[i];
  78         }
  79
  80         /* Finalize checksum and write args */
  81         args.checksum = csum & 0xFF;
  82         outb(args.flags, EC_LPC_ADDR_HOST_ARGS);
  83         outb(args.command_version, EC_LPC_ADDR_HOST_ARGS + 1);
  84         outb(args.data_size, EC_LPC_ADDR_HOST_ARGS + 2);
  85         outb(args.checksum, EC_LPC_ADDR_HOST_ARGS + 3);
  86
  87         /* Here we go */
  88         outb(msg->command, EC_LPC_ADDR_HOST_CMD);
  89
  90         if (ec_response_timed_out()) {
  91                 dev_warn(ec->dev, "EC responsed timed out\n");
  92                 ret = -EIO;
  93                 goto done;
  94         }
  95
  96         /* Check result */
  97         msg->result = inb(EC_LPC_ADDR_HOST_DATA);
  98
  99         switch (msg->result) {
 100         case EC_RES_SUCCESS:
 101                 break;
 102         case EC_RES_IN_PROGRESS:
 103                 ret = -EAGAIN;
 104                 dev_dbg(ec->dev, "command 0x%02x in progress\n",
 105                         msg->command);
 106                 goto done;
 107         default:
 108                 dev_dbg(ec->dev, "command 0x%02x returned %d\n",
 109                         msg->command, msg->result);
 110         }
 111
 112         /* Read back args */
 113         args.flags = inb(EC_LPC_ADDR_HOST_ARGS);
 114         args.command_version = inb(EC_LPC_ADDR_HOST_ARGS + 1);
 115         args.data_size = inb(EC_LPC_ADDR_HOST_ARGS + 2);
 116         args.checksum = inb(EC_LPC_ADDR_HOST_ARGS + 3);
 117
 118         if (args.data_size > msg->insize) {
 119                 dev_err(ec->dev,
 120                         "packet too long (%d bytes, expected %d)",
 121                         args.data_size, msg->insize);
 122                 ret = -ENOSPC;
 123                 goto done;
 124         }
 125
 126         /* Start calculating response checksum */
 127         csum = msg->command + args.flags +
 128                 args.command_version + args.data_size;
 129
 130         /* Read response and update checksum */
 131         for (i = 0; i < args.data_size; i++) {
 132                 msg->indata[i] = inb(EC_LPC_ADDR_HOST_PARAM + i);
 133                 csum += msg->indata[i];
 134         }
 135
 136         /* Verify checksum */
 137         if (args.checksum != (csum & 0xFF)) {
 138                 dev_err(ec->dev,
 139                         "bad packet checksum, expected %02x, got %02x\n",
 140                         args.checksum, csum & 0xFF);
 141                 ret = -EBADMSG;
 142                 goto done;
 143         }
 144
 145         /* Return actual amount of data received */
 146         ret = args.data_size;
 147 done:
 148         return ret;
 149 }
 150
 151 /* Returns num bytes read, or negative on error. Doesn't need locking. */
 152 static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
 153                                unsigned int bytes, void *dest)
 154 {
 155         int i = offset;
 156         char *s = dest;
 157         int cnt = 0;
 158
 159         if (offset >= EC_MEMMAP_SIZE - bytes)
 160                 return -EINVAL;
 161
 162         /* fixed length */
 163         if (bytes) {
 164                 for (; cnt < bytes; i++, s++, cnt++)
 165                         *s = inb(EC_LPC_ADDR_MEMMAP + i);
 166                 return cnt;
 167         }
 168
 169         /* string */
 170         for (; i < EC_MEMMAP_SIZE; i++, s++) {
 171                 *s = inb(EC_LPC_ADDR_MEMMAP + i);
 172                 cnt++;
 173                 if (!*s)
 174                         break;
 175         }
 176
 177         return cnt;
 178 }
 179
 180 static int cros_ec_lpc_probe(struct platform_device *pdev)
 181 {
 182         struct device *dev = &pdev->dev;
 183         struct cros_ec_device *ec_dev;
 184         int ret;
 185
 186         if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
 187                                  dev_name(dev))) {
 188                 dev_err(dev, "couldn't reserve memmap region\n");
 189                 return -EBUSY;
 190         }
 191
 192         if ((inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID) != 'E') ||
 193             (inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID + 1) != 'C')) {
 194                 dev_err(dev, "EC ID not detected\n");
 195                 return -ENODEV;
 196         }
 197
 198         if (!devm_request_region(dev, EC_HOST_CMD_REGION0,
 199                                  EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
 200                 dev_err(dev, "couldn't reserve region0\n");
 201                 return -EBUSY;
 202         }
 203         if (!devm_request_region(dev, EC_HOST_CMD_REGION1,
 204                                  EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
 205                 dev_err(dev, "couldn't reserve region1\n");
 206                 return -EBUSY;
 207         }
 208
 209         ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
 210         if (!ec_dev)
 211                 return -ENOMEM;
 212
 213         platform_set_drvdata(pdev, ec_dev);
 214         ec_dev->dev = dev;
 215         ec_dev->ec_name = pdev->name;
 216         ec_dev->phys_name = dev_name(dev);
 217         ec_dev->parent = dev;
 218         ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
 219         ec_dev->cmd_readmem = cros_ec_lpc_readmem;
 220
 221         ret = cros_ec_register(ec_dev);
 222         if (ret) {
 223                 dev_err(dev, "couldn't register ec_dev (%d)\n", ret);
 224                 return ret;
 225         }
 226
 227         return 0;
 228 }
 229
 230 static int cros_ec_lpc_remove(struct platform_device *pdev)
 231 {
 232         struct cros_ec_device *ec_dev;
 233
 234         ec_dev = platform_get_drvdata(pdev);
 235         cros_ec_remove(ec_dev);
 236
 237         return 0;
 238 }
 239
 240 static struct dmi_system_id cros_ec_lpc_dmi_table[] __initdata = {
 241         {
 242                 /*
 243                  * Today all Chromebooks/boxes ship with Google_* as version and
 244                  * coreboot as bios vendor. No other systems with this
 245                  * combination are known to date.
 246                  */
 247                 .matches = {
 248                         DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
 249                         DMI_MATCH(DMI_BIOS_VERSION, "Google_"),
 250                 },
 251         },
 252         {
 253                 /* x86-link, the Chromebook Pixel. */
 254                 .matches = {
 255                         DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 256                         DMI_MATCH(DMI_PRODUCT_NAME, "Link"),
 257                 },
 258         },
 259         {
 260                 /* x86-peppy, the Acer C720 Chromebook. */
 261                 .matches = {
 262                         DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
 263                         DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"),
 264                 },
 265         },
 266         { /* sentinel */ }
 267 };
 268 MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table);
 269
 270 static struct platform_driver cros_ec_lpc_driver = {
 271         .driver = {
 272                 .name = DRV_NAME,
 273         },
 274         .probe = cros_ec_lpc_probe,
 275         .remove = cros_ec_lpc_remove,
 276 };
 277
 278 static struct platform_device cros_ec_lpc_device = {
 279         .name = DRV_NAME
 280 };
 281
 282 static int __init cros_ec_lpc_init(void)
 283 {
 284         int ret;
 285
 286         if (!dmi_check_system(cros_ec_lpc_dmi_table)) {
 287                 pr_err(DRV_NAME ": unsupported system.\n");
 288                 return -ENODEV;
 289         }
 290
 291         /* Register the driver */
 292         ret = platform_driver_register(&cros_ec_lpc_driver);
 293         if (ret) {
 294                 pr_err(DRV_NAME ": can't register driver: %d\n", ret);
 295                 return ret;
 296         }
 297
 298         /* Register the device, and it'll get hooked up automatically */
 299         ret = platform_device_register(&cros_ec_lpc_device);
 300         if (ret) {
 301                 pr_err(DRV_NAME ": can't register device: %d\n", ret);
 302                 platform_driver_unregister(&cros_ec_lpc_driver);
 303                 return ret;
 304         }
 305
 306         return 0;
 307 }
 308
 309 static void __exit cros_ec_lpc_exit(void)
 310 {
 311         platform_device_unregister(&cros_ec_lpc_device);
 312         platform_driver_unregister(&cros_ec_lpc_driver);
 313 }
 314
 315 module_init(cros_ec_lpc_init);
 316 module_exit(cros_ec_lpc_exit);
 317
 318 MODULE_LICENSE("GPL");
 319 MODULE_DESCRIPTION("ChromeOS EC LPC driver");