drivers/platform/chrome/cros_ec_i2c.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // I2C interface for ChromeOS Embedded Controller
   3 //
   4 // Copyright (C) 2012 Google, Inc
   5
   6 #include <linux/acpi.h>
   7 #include <linux/delay.h>
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/i2c.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/platform_data/cros_ec_commands.h>
  13 #include <linux/platform_data/cros_ec_proto.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/slab.h>
  16
  17 #include "cros_ec.h"
  18
  19 /*
  20  * Request format for protocol v3
  21  * byte 0       0xda (EC_COMMAND_PROTOCOL_3)
  22  * byte 1-8     struct ec_host_request
  23  * byte 10-     response data
  24  */
  25 struct ec_host_request_i2c {
  26         /* Always 0xda to backward compatible with v2 struct */
  27         uint8_t  command_protocol;
  28         struct ec_host_request ec_request;
  29 } __packed;
  30
  31
  32 /*
  33  * Response format for protocol v3
  34  * byte 0       result code
  35  * byte 1       packet_length
  36  * byte 2-9     struct ec_host_response
  37  * byte 10-     response data
  38  */
  39 struct ec_host_response_i2c {
  40         uint8_t result;
  41         uint8_t packet_length;
  42         struct ec_host_response ec_response;
  43 } __packed;
  44
  45 static inline struct cros_ec_device *to_ec_dev(struct device *dev)
  46 {
  47         struct i2c_client *client = to_i2c_client(dev);
  48
  49         return i2c_get_clientdata(client);
  50 }
  51
  52 static int cros_ec_pkt_xfer_i2c(struct cros_ec_device *ec_dev,
  53                                 struct cros_ec_command *msg)
  54 {
  55         struct i2c_client *client = ec_dev->priv;
  56         int ret = -ENOMEM;
  57         int i;
  58         int packet_len;
  59         u8 *out_buf = NULL;
  60         u8 *in_buf = NULL;
  61         u8 sum;
  62         struct i2c_msg i2c_msg[2];
  63         struct ec_host_response *ec_response;
  64         struct ec_host_request_i2c *ec_request_i2c;
  65         struct ec_host_response_i2c *ec_response_i2c;
  66         int request_header_size = sizeof(struct ec_host_request_i2c);
  67         int response_header_size = sizeof(struct ec_host_response_i2c);
  68
  69         i2c_msg[0].addr = client->addr;
  70         i2c_msg[0].flags = 0;
  71         i2c_msg[1].addr = client->addr;
  72         i2c_msg[1].flags = I2C_M_RD;
  73
  74         packet_len = msg->insize + response_header_size;
  75         if (packet_len > ec_dev->din_size) {
  76                 ret = -EINVAL;
  77                 goto done;
  78         }
  79         in_buf = ec_dev->din;
  80         i2c_msg[1].len = packet_len;
  81         i2c_msg[1].buf = (char *) in_buf;
  82
  83         packet_len = msg->outsize + request_header_size;
  84         if (packet_len > ec_dev->dout_size) {
  85                 ret = -EINVAL;
  86                 goto done;
  87         }
  88         out_buf = ec_dev->dout;
  89         i2c_msg[0].len = packet_len;
  90         i2c_msg[0].buf = (char *) out_buf;
  91
  92         /* create request data */
  93         ec_request_i2c = (struct ec_host_request_i2c *) out_buf;
  94         ec_request_i2c->command_protocol = EC_COMMAND_PROTOCOL_3;
  95
  96         ec_dev->dout++;
  97         ret = cros_ec_prepare_tx(ec_dev, msg);
  98         if (ret < 0)
  99                 goto done;
 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 {
 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                             sizeof(struct ec_params_rwsig_action);
 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 void cros_ec_i2c_remove(struct i2c_client *client)
 321 {
 322         struct cros_ec_device *ec_dev = i2c_get_clientdata(client);
 323
 324         cros_ec_unregister(ec_dev);
 325 }
 326
 327 #ifdef CONFIG_PM_SLEEP
 328 static int cros_ec_i2c_suspend(struct device *dev)
 329 {
 330         struct cros_ec_device *ec_dev = to_ec_dev(dev);
 331
 332         return cros_ec_suspend(ec_dev);
 333 }
 334
 335 static int cros_ec_i2c_resume(struct device *dev)
 336 {
 337         struct cros_ec_device *ec_dev = to_ec_dev(dev);
 338
 339         return cros_ec_resume(ec_dev);
 340 }
 341 #endif
 342
 343 static const struct dev_pm_ops cros_ec_i2c_pm_ops = {
 344         SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_i2c_suspend, cros_ec_i2c_resume)
 345 };
 346
 347 #ifdef CONFIG_OF
 348 static const struct of_device_id cros_ec_i2c_of_match[] = {
 349         { .compatible = "google,cros-ec-i2c", },
 350         { /* sentinel */ },
 351 };
 352 MODULE_DEVICE_TABLE(of, cros_ec_i2c_of_match);
 353 #endif
 354
 355 static const struct i2c_device_id cros_ec_i2c_id[] = {
 356         { "cros-ec-i2c" },
 357         { }
 358 };
 359 MODULE_DEVICE_TABLE(i2c, cros_ec_i2c_id);
 360
 361 #ifdef CONFIG_ACPI
 362 static const struct acpi_device_id cros_ec_i2c_acpi_id[] = {
 363         { "GOOG0008", 0 },
 364         { /* sentinel */ }
 365 };
 366 MODULE_DEVICE_TABLE(acpi, cros_ec_i2c_acpi_id);
 367 #endif
 368
 369 static struct i2c_driver cros_ec_driver = {
 370         .driver = {
 371                 .name   = "cros-ec-i2c",
 372                 .acpi_match_table = ACPI_PTR(cros_ec_i2c_acpi_id),
 373                 .of_match_table = of_match_ptr(cros_ec_i2c_of_match),
 374                 .pm     = &cros_ec_i2c_pm_ops,
 375         },
 376         .probe          = cros_ec_i2c_probe,
 377         .remove         = cros_ec_i2c_remove,
 378         .id_table       = cros_ec_i2c_id,
 379 };
 380
 381 module_i2c_driver(cros_ec_driver);
 382
 383 MODULE_LICENSE("GPL v2");
 384 MODULE_DESCRIPTION("I2C interface for ChromeOS Embedded Controller");