drivers/platform/chrome/cros_ec_proto.c

   1 /*
   2  * ChromeOS EC communication protocol helper functions
   3  *
   4  * Copyright (C) 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  */
  16
  17 #include <linux/mfd/cros_ec.h>
  18 #include <linux/delay.h>
  19 #include <linux/device.h>
  20 #include <linux/module.h>
  21 #include <linux/slab.h>
  22 #include <asm/unaligned.h>
  23
  24 #define EC_COMMAND_RETRIES      50
  25
  26 static int prepare_packet(struct cros_ec_device *ec_dev,
  27                           struct cros_ec_command *msg)
  28 {
  29         struct ec_host_request *request;
  30         u8 *out;
  31         int i;
  32         u8 csum = 0;
  33
  34         BUG_ON(ec_dev->proto_version != EC_HOST_REQUEST_VERSION);
  35         BUG_ON(msg->outsize + sizeof(*request) > ec_dev->dout_size);
  36
  37         out = ec_dev->dout;
  38         request = (struct ec_host_request *)out;
  39         request->struct_version = EC_HOST_REQUEST_VERSION;
  40         request->checksum = 0;
  41         request->command = msg->command;
  42         request->command_version = msg->version;
  43         request->reserved = 0;
  44         request->data_len = msg->outsize;
  45
  46         for (i = 0; i < sizeof(*request); i++)
  47                 csum += out[i];
  48
  49         /* Copy data and update checksum */
  50         memcpy(out + sizeof(*request), msg->data, msg->outsize);
  51         for (i = 0; i < msg->outsize; i++)
  52                 csum += msg->data[i];
  53
  54         request->checksum = -csum;
  55
  56         return sizeof(*request) + msg->outsize;
  57 }
  58
  59 static int send_command(struct cros_ec_device *ec_dev,
  60                         struct cros_ec_command *msg)
  61 {
  62         int ret;
  63
  64         if (ec_dev->proto_version > 2)
  65                 ret = ec_dev->pkt_xfer(ec_dev, msg);
  66         else
  67                 ret = ec_dev->cmd_xfer(ec_dev, msg);
  68
  69         if (msg->result == EC_RES_IN_PROGRESS) {
  70                 int i;
  71                 struct cros_ec_command *status_msg;
  72                 struct ec_response_get_comms_status *status;
  73
  74                 status_msg = kmalloc(sizeof(*status_msg) + sizeof(*status),
  75                                      GFP_KERNEL);
  76                 if (!status_msg)
  77                         return -ENOMEM;
  78
  79                 status_msg->version = 0;
  80                 status_msg->command = EC_CMD_GET_COMMS_STATUS;
  81                 status_msg->insize = sizeof(*status);
  82                 status_msg->outsize = 0;
  83
  84                 /*
  85                  * Query the EC's status until it's no longer busy or
  86                  * we encounter an error.
  87                  */
  88                 for (i = 0; i < EC_COMMAND_RETRIES; i++) {
  89                         usleep_range(10000, 11000);
  90
  91                         ret = ec_dev->cmd_xfer(ec_dev, status_msg);
  92                         if (ret < 0)
  93                                 break;
  94
  95                         msg->result = status_msg->result;
  96                         if (status_msg->result != EC_RES_SUCCESS)
  97                                 break;
  98
  99                         status = (struct ec_response_get_comms_status *)
 100                                  status_msg->data;
 101                         if (!(status->flags & EC_COMMS_STATUS_PROCESSING))
 102                                 break;
 103                 }
 104
 105                 kfree(status_msg);
 106         }
 107
 108         return ret;
 109 }
 110
 111 int cros_ec_prepare_tx(struct cros_ec_device *ec_dev,
 112                        struct cros_ec_command *msg)
 113 {
 114         u8 *out;
 115         u8 csum;
 116         int i;
 117
 118         if (ec_dev->proto_version > 2)
 119                 return prepare_packet(ec_dev, msg);
 120
 121         BUG_ON(msg->outsize > EC_PROTO2_MAX_PARAM_SIZE);
 122         out = ec_dev->dout;
 123         out[0] = EC_CMD_VERSION0 + msg->version;
 124         out[1] = msg->command;
 125         out[2] = msg->outsize;
 126         csum = out[0] + out[1] + out[2];
 127         for (i = 0; i < msg->outsize; i++)
 128                 csum += out[EC_MSG_TX_HEADER_BYTES + i] = msg->data[i];
 129         out[EC_MSG_TX_HEADER_BYTES + msg->outsize] = csum;
 130
 131         return EC_MSG_TX_PROTO_BYTES + msg->outsize;
 132 }
 133 EXPORT_SYMBOL(cros_ec_prepare_tx);
 134
 135 int cros_ec_check_result(struct cros_ec_device *ec_dev,
 136                          struct cros_ec_command *msg)
 137 {
 138         switch (msg->result) {
 139         case EC_RES_SUCCESS:
 140                 return 0;
 141         case EC_RES_IN_PROGRESS:
 142                 dev_dbg(ec_dev->dev, "command 0x%02x in progress\n",
 143                         msg->command);
 144                 return -EAGAIN;
 145         default:
 146                 dev_dbg(ec_dev->dev, "command 0x%02x returned %d\n",
 147                         msg->command, msg->result);
 148                 return 0;
 149         }
 150 }
 151 EXPORT_SYMBOL(cros_ec_check_result);
 152
 153 static int cros_ec_host_command_proto_query(struct cros_ec_device *ec_dev,
 154                                             int devidx,
 155                                             struct cros_ec_command *msg)
 156 {
 157         /*
 158          * Try using v3+ to query for supported protocols. If this
 159          * command fails, fall back to v2. Returns the highest protocol
 160          * supported by the EC.
 161          * Also sets the max request/response/passthru size.
 162          */
 163         int ret;
 164
 165         if (!ec_dev->pkt_xfer)
 166                 return -EPROTONOSUPPORT;
 167
 168         memset(msg, 0, sizeof(*msg));
 169         msg->command = EC_CMD_PASSTHRU_OFFSET(devidx) | EC_CMD_GET_PROTOCOL_INFO;
 170         msg->insize = sizeof(struct ec_response_get_protocol_info);
 171
 172         ret = send_command(ec_dev, msg);
 173
 174         if (ret < 0) {
 175                 dev_dbg(ec_dev->dev,
 176                         "failed to check for EC[%d] protocol version: %d\n",
 177                         devidx, ret);
 178                 return ret;
 179         }
 180
 181         if (devidx > 0 && msg->result == EC_RES_INVALID_COMMAND)
 182                 return -ENODEV;
 183         else if (msg->result != EC_RES_SUCCESS)
 184                 return msg->result;
 185
 186         return 0;
 187 }
 188
 189 static int cros_ec_host_command_proto_query_v2(struct cros_ec_device *ec_dev)
 190 {
 191         struct cros_ec_command *msg;
 192         struct ec_params_hello *hello_params;
 193         struct ec_response_hello *hello_response;
 194         int ret;
 195         int len = max(sizeof(*hello_params), sizeof(*hello_response));
 196
 197         msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
 198         if (!msg)
 199                 return -ENOMEM;
 200
 201         msg->version = 0;
 202         msg->command = EC_CMD_HELLO;
 203         hello_params = (struct ec_params_hello *)msg->data;
 204         msg->outsize = sizeof(*hello_params);
 205         hello_response = (struct ec_response_hello *)msg->data;
 206         msg->insize = sizeof(*hello_response);
 207
 208         hello_params->in_data = 0xa0b0c0d0;
 209
 210         ret = send_command(ec_dev, msg);
 211
 212         if (ret < 0) {
 213                 dev_dbg(ec_dev->dev,
 214                         "EC failed to respond to v2 hello: %d\n",
 215                         ret);
 216                 goto exit;
 217         } else if (msg->result != EC_RES_SUCCESS) {
 218                 dev_err(ec_dev->dev,
 219                         "EC responded to v2 hello with error: %d\n",
 220                         msg->result);
 221                 ret = msg->result;
 222                 goto exit;
 223         } else if (hello_response->out_data != 0xa1b2c3d4) {
 224                 dev_err(ec_dev->dev,
 225                         "EC responded to v2 hello with bad result: %u\n",
 226                         hello_response->out_data);
 227                 ret = -EBADMSG;
 228                 goto exit;
 229         }
 230
 231         ret = 0;
 232
 233  exit:
 234         kfree(msg);
 235         return ret;
 236 }
 237
 238 static int cros_ec_get_host_command_version_mask(struct cros_ec_device *ec_dev,
 239         u16 cmd, u32 *mask)
 240 {
 241         struct ec_params_get_cmd_versions *pver;
 242         struct ec_response_get_cmd_versions *rver;
 243         struct cros_ec_command *msg;
 244         int ret;
 245
 246         msg = kmalloc(sizeof(*msg) + max(sizeof(*rver), sizeof(*pver)),
 247                       GFP_KERNEL);
 248         if (!msg)
 249                 return -ENOMEM;
 250
 251         msg->version = 0;
 252         msg->command = EC_CMD_GET_CMD_VERSIONS;
 253         msg->insize = sizeof(*rver);
 254         msg->outsize = sizeof(*pver);
 255
 256         pver = (struct ec_params_get_cmd_versions *)msg->data;
 257         pver->cmd = cmd;
 258
 259         ret = cros_ec_cmd_xfer(ec_dev, msg);
 260         if (ret > 0) {
 261                 rver = (struct ec_response_get_cmd_versions *)msg->data;
 262                 *mask = rver->version_mask;
 263         }
 264
 265         kfree(msg);
 266
 267         return ret;
 268 }
 269
 270 int cros_ec_query_all(struct cros_ec_device *ec_dev)
 271 {
 272         struct device *dev = ec_dev->dev;
 273         struct cros_ec_command *proto_msg;
 274         struct ec_response_get_protocol_info *proto_info;
 275         u32 ver_mask = 0;
 276         int ret;
 277
 278         proto_msg = kzalloc(sizeof(*proto_msg) + sizeof(*proto_info),
 279                             GFP_KERNEL);
 280         if (!proto_msg)
 281                 return -ENOMEM;
 282
 283         /* First try sending with proto v3. */
 284         ec_dev->proto_version = 3;
 285         ret = cros_ec_host_command_proto_query(ec_dev, 0, proto_msg);
 286
 287         if (ret == 0) {
 288                 proto_info = (struct ec_response_get_protocol_info *)
 289                         proto_msg->data;
 290                 ec_dev->max_request = proto_info->max_request_packet_size -
 291                         sizeof(struct ec_host_request);
 292                 ec_dev->max_response = proto_info->max_response_packet_size -
 293                         sizeof(struct ec_host_response);
 294                 ec_dev->proto_version =
 295                         min(EC_HOST_REQUEST_VERSION,
 296                                         fls(proto_info->protocol_versions) - 1);
 297                 dev_dbg(ec_dev->dev,
 298                         "using proto v%u\n",
 299                         ec_dev->proto_version);
 300
 301                 ec_dev->din_size = ec_dev->max_response +
 302                         sizeof(struct ec_host_response) +
 303                         EC_MAX_RESPONSE_OVERHEAD;
 304                 ec_dev->dout_size = ec_dev->max_request +
 305                         sizeof(struct ec_host_request) +
 306                         EC_MAX_REQUEST_OVERHEAD;
 307
 308                 /*
 309                  * Check for PD
 310                  */
 311                 ret = cros_ec_host_command_proto_query(ec_dev, 1, proto_msg);
 312
 313                 if (ret) {
 314                         dev_dbg(ec_dev->dev, "no PD chip found: %d\n", ret);
 315                         ec_dev->max_passthru = 0;
 316                 } else {
 317                         dev_dbg(ec_dev->dev, "found PD chip\n");
 318                         ec_dev->max_passthru =
 319                                 proto_info->max_request_packet_size -
 320                                 sizeof(struct ec_host_request);
 321                 }
 322         } else {
 323                 /* Try querying with a v2 hello message. */
 324                 ec_dev->proto_version = 2;
 325                 ret = cros_ec_host_command_proto_query_v2(ec_dev);
 326
 327                 if (ret == 0) {
 328                         /* V2 hello succeeded. */
 329                         dev_dbg(ec_dev->dev, "falling back to proto v2\n");
 330
 331                         ec_dev->max_request = EC_PROTO2_MAX_PARAM_SIZE;
 332                         ec_dev->max_response = EC_PROTO2_MAX_PARAM_SIZE;
 333                         ec_dev->max_passthru = 0;
 334                         ec_dev->pkt_xfer = NULL;
 335                         ec_dev->din_size = EC_PROTO2_MSG_BYTES;
 336                         ec_dev->dout_size = EC_PROTO2_MSG_BYTES;
 337                 } else {
 338                         /*
 339                          * It's possible for a test to occur too early when
 340                          * the EC isn't listening. If this happens, we'll
 341                          * test later when the first command is run.
 342                          */
 343                         ec_dev->proto_version = EC_PROTO_VERSION_UNKNOWN;
 344                         dev_dbg(ec_dev->dev, "EC query failed: %d\n", ret);
 345                         goto exit;
 346                 }
 347         }
 348
 349         devm_kfree(dev, ec_dev->din);
 350         devm_kfree(dev, ec_dev->dout);
 351
 352         ec_dev->din = devm_kzalloc(dev, ec_dev->din_size, GFP_KERNEL);
 353         if (!ec_dev->din) {
 354                 ret = -ENOMEM;
 355                 goto exit;
 356         }
 357
 358         ec_dev->dout = devm_kzalloc(dev, ec_dev->dout_size, GFP_KERNEL);
 359         if (!ec_dev->dout) {
 360                 devm_kfree(dev, ec_dev->din);
 361                 ret = -ENOMEM;
 362                 goto exit;
 363         }
 364
 365         /* Probe if MKBP event is supported */
 366         ret = cros_ec_get_host_command_version_mask(ec_dev,
 367                                                     EC_CMD_GET_NEXT_EVENT,
 368                                                     &ver_mask);
 369         if (ret < 0 || ver_mask == 0)
 370                 ec_dev->mkbp_event_supported = 0;
 371         else
 372                 ec_dev->mkbp_event_supported = 1;
 373
 374 exit:
 375         kfree(proto_msg);
 376         return ret;
 377 }
 378 EXPORT_SYMBOL(cros_ec_query_all);
 379
 380 int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
 381                      struct cros_ec_command *msg)
 382 {
 383         int ret;
 384
 385         mutex_lock(&ec_dev->lock);
 386         if (ec_dev->proto_version == EC_PROTO_VERSION_UNKNOWN) {
 387                 ret = cros_ec_query_all(ec_dev);
 388                 if (ret) {
 389                         dev_err(ec_dev->dev,
 390                                 "EC version unknown and query failed; aborting command\n");
 391                         mutex_unlock(&ec_dev->lock);
 392                         return ret;
 393                 }
 394         }
 395
 396         if (msg->insize > ec_dev->max_response) {
 397                 dev_dbg(ec_dev->dev, "clamping message receive buffer\n");
 398                 msg->insize = ec_dev->max_response;
 399         }
 400
 401         if (msg->command < EC_CMD_PASSTHRU_OFFSET(1)) {
 402                 if (msg->outsize > ec_dev->max_request) {
 403                         dev_err(ec_dev->dev,
 404                                 "request of size %u is too big (max: %u)\n",
 405                                 msg->outsize,
 406                                 ec_dev->max_request);
 407                         mutex_unlock(&ec_dev->lock);
 408                         return -EMSGSIZE;
 409                 }
 410         } else {
 411                 if (msg->outsize > ec_dev->max_passthru) {
 412                         dev_err(ec_dev->dev,
 413                                 "passthru rq of size %u is too big (max: %u)\n",
 414                                 msg->outsize,
 415                                 ec_dev->max_passthru);
 416                         mutex_unlock(&ec_dev->lock);
 417                         return -EMSGSIZE;
 418                 }
 419         }
 420         ret = send_command(ec_dev, msg);
 421         mutex_unlock(&ec_dev->lock);
 422
 423         return ret;
 424 }
 425 EXPORT_SYMBOL(cros_ec_cmd_xfer);
 426
 427 int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
 428                             struct cros_ec_command *msg)
 429 {
 430         int ret;
 431
 432         ret = cros_ec_cmd_xfer(ec_dev, msg);
 433         if (ret < 0) {
 434                 dev_err(ec_dev->dev, "Command xfer error (err:%d)\n", ret);
 435         } else if (msg->result != EC_RES_SUCCESS) {
 436                 dev_dbg(ec_dev->dev, "Command result (err: %d)\n", msg->result);
 437                 return -EPROTO;
 438         }
 439
 440         return ret;
 441 }
 442 EXPORT_SYMBOL(cros_ec_cmd_xfer_status);
 443
 444 static int get_next_event(struct cros_ec_device *ec_dev)
 445 {
 446         u8 buffer[sizeof(struct cros_ec_command) + sizeof(ec_dev->event_data)];
 447         struct cros_ec_command *msg = (struct cros_ec_command *)&buffer;
 448         int ret;
 449
 450         msg->version = 0;
 451         msg->command = EC_CMD_GET_NEXT_EVENT;
 452         msg->insize = sizeof(ec_dev->event_data);
 453         msg->outsize = 0;
 454
 455         ret = cros_ec_cmd_xfer(ec_dev, msg);
 456         if (ret > 0) {
 457                 ec_dev->event_size = ret - 1;
 458                 memcpy(&ec_dev->event_data, msg->data,
 459                        sizeof(ec_dev->event_data));
 460         }
 461
 462         return ret;
 463 }
 464
 465 static int get_keyboard_state_event(struct cros_ec_device *ec_dev)
 466 {
 467         u8 buffer[sizeof(struct cros_ec_command) +
 468                   sizeof(ec_dev->event_data.data)];
 469         struct cros_ec_command *msg = (struct cros_ec_command *)&buffer;
 470
 471         msg->version = 0;
 472         msg->command = EC_CMD_MKBP_STATE;
 473         msg->insize = sizeof(ec_dev->event_data.data);
 474         msg->outsize = 0;
 475
 476         ec_dev->event_size = cros_ec_cmd_xfer(ec_dev, msg);
 477         ec_dev->event_data.event_type = EC_MKBP_EVENT_KEY_MATRIX;
 478         memcpy(&ec_dev->event_data.data, msg->data,
 479                sizeof(ec_dev->event_data.data));
 480
 481         return ec_dev->event_size;
 482 }
 483
 484 int cros_ec_get_next_event(struct cros_ec_device *ec_dev)
 485 {
 486         if (ec_dev->mkbp_event_supported)
 487                 return get_next_event(ec_dev);
 488         else
 489                 return get_keyboard_state_event(ec_dev);
 490 }
 491 EXPORT_SYMBOL(cros_ec_get_next_event);