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