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