drivers/platform/chrome/cros_ec_i2c.c

   1 /*
   2  * ChromeOS EC multi-function device (I2C)
   3  *
   4  * Copyright (C) 2012 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
  16 #include <linux/acpi.h>
  17 #include <linux/delay.h>
  18 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20 #include <linux/i2c.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/mfd/cros_ec.h>
  23 #include <linux/mfd/cros_ec_commands.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/slab.h>
  26
  27 /**
  28  * Request format for protocol v3
  29  * byte 0       0xda (EC_COMMAND_PROTOCOL_3)
  30  * byte 1-8     struct ec_host_request
  31  * byte 10-     response data
  32  */
  33 struct ec_host_request_i2c {
  34         /* Always 0xda to backward compatible with v2 struct */
  35         uint8_t  command_protocol;
  36         struct ec_host_request ec_request;
  37 } __packed;
  38
  39
  40 /*
  41  * Response format for protocol v3
  42  * byte 0       result code
  43  * byte 1       packet_length
  44  * byte 2-9     struct ec_host_response
  45  * byte 10-     response data
  46  */
  47 struct ec_host_response_i2c {
  48         uint8_t result;
  49         uint8_t packet_length;
  50         struct ec_host_response ec_response;
  51 } __packed;
  52
  53 static inline struct cros_ec_device *to_ec_dev(struct device *dev)
  54 {
  55         struct i2c_client *client = to_i2c_client(dev);
  56
  57         return i2c_get_clientdata(client);
  58 }
  59
  60 static int cros_ec_pkt_xfer_i2c(struct cros_ec_device *ec_dev,
  61                                 struct cros_ec_command *msg)
  62 {
  63         struct i2c_client *client = ec_dev->priv;
  64         int ret = -ENOMEM;
  65         int i;
  66         int packet_len;
  67         u8 *out_buf = NULL;
  68         u8 *in_buf = NULL;
  69         u8 sum;
  70         struct i2c_msg i2c_msg[2];
  71         struct ec_host_response *ec_response;
  72         struct ec_host_request_i2c *ec_request_i2c;
  73         struct ec_host_response_i2c *ec_response_i2c;
  74         int request_header_size = sizeof(struct ec_host_request_i2c);
  75         int response_header_size = sizeof(struct ec_host_response_i2c);
  76
  77         i2c_msg[0].addr = client->addr;
  78         i2c_msg[0].flags = 0;
  79         i2c_msg[1].addr = client->addr;
  80         i2c_msg[1].flags = I2C_M_RD;
  81
  82         packet_len = msg->insize + response_header_size;
  83         BUG_ON(packet_len > ec_dev->din_size);
  84         in_buf = ec_dev->din;
  85         i2c_msg[1].len = packet_len;
  86         i2c_msg[1].buf = (char *) in_buf;
  87
  88         packet_len = msg->outsize + request_header_size;
  89         BUG_ON(packet_len > ec_dev->dout_size);
  90         out_buf = ec_dev->dout;
  91         i2c_msg[0].len = packet_len;
  92         i2c_msg[0].buf = (char *) out_buf;
  93
  94         /* create request data */
  95         ec_request_i2c = (struct ec_host_request_i2c *) out_buf;
  96         ec_request_i2c->command_protocol = EC_COMMAND_PROTOCOL_3;
  97
  98         ec_dev->dout++;
  99         ret = cros_ec_prepare_tx(ec_dev, msg);
 100         ec_dev->dout--;
 101
 102         /* send command to EC and read answer */
 103         ret = i2c_transfer(client->adapter, i2c_msg, 2);
 104         if (ret < 0) {
 105                 dev_dbg(ec_dev->dev, "i2c transfer failed: %d\n", ret);
 106                 goto done;
 107         } else if (ret != 2) {
 108                 dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
 109                 ret = -EIO;
 110                 goto done;
 111         }
 112
 113         ec_response_i2c = (struct ec_host_response_i2c *) in_buf;
 114         msg->result = ec_response_i2c->result;
 115         ec_response = &ec_response_i2c->ec_response;
 116
 117         switch (msg->result) {
 118         case EC_RES_SUCCESS:
 119                 break;
 120         case EC_RES_IN_PROGRESS:
 121                 ret = -EAGAIN;
 122                 dev_dbg(ec_dev->dev, "command 0x%02x in progress\n",
 123                         msg->command);
 124                 goto done;
 125
 126         default:
 127                 dev_dbg(ec_dev->dev, "command 0x%02x returned %d\n",
 128                         msg->command, msg->result);
 129                 /*
 130                  * When we send v3 request to v2 ec, ec won't recognize the
 131                  * 0xda (EC_COMMAND_PROTOCOL_3) and will return with status
 132                  * EC_RES_INVALID_COMMAND with zero data length.
 133                  *
 134                  * In case of invalid command for v3 protocol the data length
 135                  * will be at least sizeof(struct ec_host_response)
 136                  */
 137                 if (ec_response_i2c->result == EC_RES_INVALID_COMMAND &&
 138                     ec_response_i2c->packet_length == 0) {
 139                         ret = -EPROTONOSUPPORT;
 140                         goto done;
 141                 }
 142         }
 143
 144         if (ec_response_i2c->packet_length < sizeof(struct ec_host_response)) {
 145                 dev_err(ec_dev->dev,
 146                         "response of %u bytes too short; not a full header\n",
 147                         ec_response_i2c->packet_length);
 148                 ret = -EBADMSG;
 149                 goto done;
 150         }
 151
 152         if (msg->insize < ec_response->data_len) {
 153                 dev_err(ec_dev->dev,
 154                         "response data size is too large: expected %u, got %u\n",
 155                         msg->insize,
 156                         ec_response->data_len);
 157                 ret = -EMSGSIZE;
 158                 goto done;
 159         }
 160
 161         /* copy response packet payload and compute checksum */
 162         sum = 0;
 163         for (i = 0; i < sizeof(struct ec_host_response); i++)
 164                 sum += ((u8 *)ec_response)[i];
 165
 166         memcpy(msg->data,
 167                in_buf + response_header_size,
 168                ec_response->data_len);
 169         for (i = 0; i < ec_response->data_len; i++)
 170                 sum += msg->data[i];
 171
 172         /* All bytes should sum to zero */
 173         if (sum) {
 174                 dev_err(ec_dev->dev, "bad packet checksum\n");
 175                 ret = -EBADMSG;
 176                 goto done;
 177         }
 178
 179         ret = ec_response->data_len;
 180
 181 done:
 182         if (msg->command == EC_CMD_REBOOT_EC)
 183                 msleep(EC_REBOOT_DELAY_MS);
 184
 185         return ret;
 186 }
 187
 188 static int cros_ec_cmd_xfer_i2c(struct cros_ec_device *ec_dev,
 189                                 struct cros_ec_command *msg)
 190 {
 191         struct i2c_client *client = ec_dev->priv;
 192         int ret = -ENOMEM;
 193         int i;
 194         int len;
 195         int packet_len;
 196         u8 *out_buf = NULL;
 197         u8 *in_buf = NULL;
 198         u8 sum;
 199         struct i2c_msg i2c_msg[2];
 200
 201         i2c_msg[0].addr = client->addr;
 202         i2c_msg[0].flags = 0;
 203         i2c_msg[1].addr = client->addr;
 204         i2c_msg[1].flags = I2C_M_RD;
 205
 206         /*
 207          * allocate larger packet (one byte for checksum, one byte for
 208          * length, and one for result code)
 209          */
 210         packet_len = msg->insize + 3;
 211         in_buf = kzalloc(packet_len, GFP_KERNEL);
 212         if (!in_buf)
 213                 goto done;
 214         i2c_msg[1].len = packet_len;
 215         i2c_msg[1].buf = (char *)in_buf;
 216
 217         /*
 218          * allocate larger packet (one byte for checksum, one for
 219          * command code, one for length, and one for command version)
 220          */
 221         packet_len = msg->outsize + 4;
 222         out_buf = kzalloc(packet_len, GFP_KERNEL);
 223         if (!out_buf)
 224                 goto done;
 225         i2c_msg[0].len = packet_len;
 226         i2c_msg[0].buf = (char *)out_buf;
 227
 228         out_buf[0] = EC_CMD_VERSION0 + msg->version;
 229         out_buf[1] = msg->command;
 230         out_buf[2] = msg->outsize;
 231
 232         /* copy message payload and compute checksum */
 233         sum = out_buf[0] + out_buf[1] + out_buf[2];
 234         for (i = 0; i < msg->outsize; i++) {
 235                 out_buf[3 + i] = msg->data[i];
 236                 sum += out_buf[3 + i];
 237         }
 238         out_buf[3 + msg->outsize] = sum;
 239
 240         /* send command to EC and read answer */
 241         ret = i2c_transfer(client->adapter, i2c_msg, 2);
 242         if (ret < 0) {
 243                 dev_err(ec_dev->dev, "i2c transfer failed: %d\n", ret);
 244                 goto done;
 245         } else if (ret != 2) {
 246                 dev_err(ec_dev->dev, "failed to get response: %d\n", ret);
 247                 ret = -EIO;
 248                 goto done;
 249         }
 250
 251         /* check response error code */
 252         msg->result = i2c_msg[1].buf[0];
 253         ret = cros_ec_check_result(ec_dev, msg);
 254         if (ret)
 255                 goto done;
 256
 257         len = in_buf[1];
 258         if (len > msg->insize) {
 259                 dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
 260                         len, msg->insize);
 261                 ret = -ENOSPC;
 262                 goto done;
 263         }
 264
 265         /* copy response packet payload and compute checksum */
 266         sum = in_buf[0] + in_buf[1];
 267         for (i = 0; i < len; i++) {
 268                 msg->data[i] = in_buf[2 + i];
 269                 sum += in_buf[2 + i];
 270         }
 271         dev_dbg(ec_dev->dev, "packet: %*ph, sum = %02x\n",
 272                 i2c_msg[1].len, in_buf, sum);
 273         if (sum != in_buf[2 + len]) {
 274                 dev_err(ec_dev->dev, "bad packet checksum\n");
 275                 ret = -EBADMSG;
 276                 goto done;
 277         }
 278
 279         ret = len;
 280 done:
 281         kfree(in_buf);
 282         kfree(out_buf);
 283         if (msg->command == EC_CMD_REBOOT_EC)
 284                 msleep(EC_REBOOT_DELAY_MS);
 285
 286         return ret;
 287 }
 288
 289 static int cros_ec_i2c_probe(struct i2c_client *client,
 290                              const struct i2c_device_id *dev_id)
 291 {
 292         struct device *dev = &client->dev;
 293         struct cros_ec_device *ec_dev = NULL;
 294         int err;
 295
 296         ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
 297         if (!ec_dev)
 298                 return -ENOMEM;
 299
 300         i2c_set_clientdata(client, ec_dev);
 301         ec_dev->dev = dev;
 302         ec_dev->priv = client;
 303         ec_dev->irq = client->irq;
 304         ec_dev->cmd_xfer = cros_ec_cmd_xfer_i2c;
 305         ec_dev->pkt_xfer = cros_ec_pkt_xfer_i2c;
 306         ec_dev->phys_name = client->adapter->name;
 307         ec_dev->din_size = sizeof(struct ec_host_response_i2c) +
 308                            sizeof(struct ec_response_get_protocol_info);
 309         ec_dev->dout_size = sizeof(struct ec_host_request_i2c);
 310
 311         err = cros_ec_register(ec_dev);
 312         if (err) {
 313                 dev_err(dev, "cannot register EC\n");
 314                 return err;
 315         }
 316
 317         return 0;
 318 }
 319
 320 static int cros_ec_i2c_remove(struct i2c_client *client)
 321 {
 322         struct cros_ec_device *ec_dev = i2c_get_clientdata(client);
 323
 324         cros_ec_remove(ec_dev);
 325
 326         return 0;
 327 }
 328
 329 #ifdef CONFIG_PM_SLEEP
 330 static int cros_ec_i2c_suspend(struct device *dev)
 331 {
 332         struct cros_ec_device *ec_dev = to_ec_dev(dev);
 333
 334         return cros_ec_suspend(ec_dev);
 335 }
 336
 337 static int cros_ec_i2c_resume(struct device *dev)
 338 {
 339         struct cros_ec_device *ec_dev = to_ec_dev(dev);
 340
 341         return cros_ec_resume(ec_dev);
 342 }
 343 #endif
 344
 345 static const struct dev_pm_ops cros_ec_i2c_pm_ops = {
 346         SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_i2c_suspend, cros_ec_i2c_resume)
 347 };
 348
 349 #ifdef CONFIG_OF
 350 static const struct of_device_id cros_ec_i2c_of_match[] = {
 351         { .compatible = "google,cros-ec-i2c", },
 352         { /* sentinel */ },
 353 };
 354 MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);
 355 #endif
 356
 357 static const struct i2c_device_id cros_ec_i2c_id[] = {
 358         { "cros-ec-i2c", 0 },
 359         { }
 360 };
 361 MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
 362
 363 #ifdef CONFIG_ACPI
 364 static const struct acpi_device_id cros_ec_i2c_acpi_id[] = {
 365         { "GOOG0008", 0 },
 366         { /* sentinel */ }
 367 };
 368 MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_acpi_id);
 369 #endif
 370
 371 static struct i2c_driver cros_ec_driver = {
 372         .driver = {
 373                 .name   = "cros-ec-i2c",
 374                 .acpi_match_table = ACPI_PTR(cros_ec_i2c_acpi_id),
 375                 .of_match_table = of_match_ptr(cros_ec_i2c_of_match),
 376                 .pm     = &cros_ec_i2c_pm_ops,
 377         },
 378         .probe          = cros_ec_i2c_probe,
 379         .remove         = cros_ec_i2c_remove,
 380         .id_table       = cros_ec_i2c_id,
 381 };
 382
 383 module_i2c_driver(cros_ec_driver);
 384
 385 MODULE_LICENSE("GPL");
 386 MODULE_DESCRIPTION("ChromeOS EC multi function device");