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
  23 #define EC_COMMAND_RETRIES      50
  24
  25 static int prepare_packet(struct cros_ec_device *ec_dev,
  26                           struct cros_ec_command *msg)
  27 {
  28         struct ec_host_request *request;
  29         u8 *out;
  30         int i;
  31         u8 csum = 0;
  32
  33         BUG_ON(ec_dev->proto_version != EC_HOST_REQUEST_VERSION);
  34         BUG_ON(msg->outsize + sizeof(*request) > ec_dev->dout_size);
  35
  36         out = ec_dev->dout;
  37         request = (struct ec_host_request *)out;
  38         request->struct_version = EC_HOST_REQUEST_VERSION;
  39         request->checksum = 0;
  40         request->command = msg->command;
  41         request->command_version = msg->version;
  42         request->reserved = 0;
  43         request->data_len = msg->outsize;
  44
  45         for (i = 0; i < sizeof(*request); i++)
  46                 csum += out[i];
  47
  48         /* Copy data and update checksum */
  49         memcpy(out + sizeof(*request), msg->data, msg->outsize);
  50         for (i = 0; i < msg->outsize; i++)
  51                 csum += msg->data[i];
  52
  53         request->checksum = -csum;
  54
  55         return sizeof(*request) + msg->outsize;
  56 }
  57
  58 static int send_command(struct cros_ec_device *ec_dev,
  59                         struct cros_ec_command *msg)
  60 {
  61         int ret;
  62         int (*xfer_fxn)(struct cros_ec_device *ec, struct cros_ec_command *msg);
  63
  64         if (ec_dev->proto_version > 2)
  65                 xfer_fxn = ec_dev->pkt_xfer;
  66         else
  67                 xfer_fxn = ec_dev->cmd_xfer;
  68
  69         if (!xfer_fxn) {
  70                 /*
  71                  * This error can happen if a communication error happened and
  72                  * the EC is trying to use protocol v2, on an underlying
  73                  * communication mechanism that does not support v2.
  74                  */
  75                 dev_err_once(ec_dev->dev,
  76                              "missing EC transfer API, cannot send command\n");
  77                 return -EIO;
  78         }
  79
  80         ret = (*xfer_fxn)(ec_dev, msg);
  81         if (msg->result == EC_RES_IN_PROGRESS) {
  82                 int i;
  83                 struct cros_ec_command *status_msg;
  84                 struct ec_response_get_comms_status *status;
  85
  86                 status_msg = kmalloc(sizeof(*status_msg) + sizeof(*status),
  87                                      GFP_KERNEL);
  88                 if (!status_msg)
  89                         return -ENOMEM;
  90
  91                 status_msg->version = 0;
  92                 status_msg->command = EC_CMD_GET_COMMS_STATUS;
  93                 status_msg->insize = sizeof(*status);
  94                 status_msg->outsize = 0;
  95
  96                 /*
  97                  * Query the EC's status until it's no longer busy or
  98                  * we encounter an error.
  99                  */
 100                 for (i = 0; i < EC_COMMAND_RETRIES; i++) {
 101                         usleep_range(10000, 11000);
 102
 103                         ret = (*xfer_fxn)(ec_dev, status_msg);
 104                         if (ret < 0)
 105                                 break;
 106
 107                         msg->result = status_msg->result;
 108                         if (status_msg->result != EC_RES_SUCCESS)
 109                                 break;
 110
 111                         status = (struct ec_response_get_comms_status *)
 112                                  status_msg->data;
 113                         if (!(status->flags & EC_COMMS_STATUS_PROCESSING))
 114                                 break;
 115                 }
 116
 117                 kfree(status_msg);
 118         }
 119
 120         return ret;
 121 }
 122
 123 int cros_ec_prepare_tx(struct cros_ec_device *ec_dev,
 124                        struct cros_ec_command *msg)
 125 {
 126         u8 *out;
 127         u8 csum;
 128         int i;
 129
 130         if (ec_dev->proto_version > 2)
 131                 return prepare_packet(ec_dev, msg);
 132
 133         BUG_ON(msg->outsize > EC_PROTO2_MAX_PARAM_SIZE);
 134         out = ec_dev->dout;
 135         out[0] = EC_CMD_VERSION0 + msg->version;
 136         out[1] = msg->command;
 137         out[2] = msg->outsize;
 138         csum = out[0] + out[1] + out[2];
 139         for (i = 0; i < msg->outsize; i++)
 140                 csum += out[EC_MSG_TX_HEADER_BYTES + i] = msg->data[i];
 141         out[EC_MSG_TX_HEADER_BYTES + msg->outsize] = csum;
 142
 143         return EC_MSG_TX_PROTO_BYTES + msg->outsize;
 144 }
 145 EXPORT_SYMBOL(cros_ec_prepare_tx);
 146
 147 int cros_ec_check_result(struct cros_ec_device *ec_dev,
 148                          struct cros_ec_command *msg)
 149 {
 150         switch (msg->result) {
 151         case EC_RES_SUCCESS:
 152                 return 0;
 153         case EC_RES_IN_PROGRESS:
 154                 dev_dbg(ec_dev->dev, "command 0x%02x in progress\n",
 155                         msg->command);
 156                 return -EAGAIN;
 157         default:
 158                 dev_dbg(ec_dev->dev, "command 0x%02x returned %d\n",
 159                         msg->command, msg->result);
 160                 return 0;
 161         }
 162 }
 163 EXPORT_SYMBOL(cros_ec_check_result);
 164
 165 static int cros_ec_host_command_proto_query(struct cros_ec_device *ec_dev,
 166                                             int devidx,
 167                                             struct cros_ec_command *msg)
 168 {
 169         /*
 170          * Try using v3+ to query for supported protocols. If this
 171          * command fails, fall back to v2. Returns the highest protocol
 172          * supported by the EC.
 173          * Also sets the max request/response/passthru size.
 174          */
 175         int ret;
 176
 177         if (!ec_dev->pkt_xfer)
 178                 return -EPROTONOSUPPORT;
 179
 180         memset(msg, 0, sizeof(*msg));
 181         msg->command = EC_CMD_PASSTHRU_OFFSET(devidx) | EC_CMD_GET_PROTOCOL_INFO;
 182         msg->insize = sizeof(struct ec_response_get_protocol_info);
 183
 184         ret = send_command(ec_dev, msg);
 185         /*
 186          * Send command once again when timeout occurred.
 187          * Fingerprint MCU (FPMCU) is restarted during system boot which
 188          * introduces small window in which FPMCU won't respond for any
 189          * messages sent by kernel. There is no need to wait before next
 190          * attempt because we waited at least EC_MSG_DEADLINE_MS.
 191          */
 192         if (ret == -ETIMEDOUT)
 193                 ret = send_command(ec_dev, msg);
 194
 195         if (ret < 0) {
 196                 dev_dbg(ec_dev->dev,
 197                         "failed to check for EC[%d] protocol version: %d\n",
 198                         devidx, ret);
 199                 return ret;
 200         }
 201
 202         if (devidx > 0 && msg->result == EC_RES_INVALID_COMMAND)
 203                 return -ENODEV;
 204         else if (msg->result != EC_RES_SUCCESS)
 205                 return msg->result;
 206
 207         return 0;
 208 }
 209
 210 static int cros_ec_host_command_proto_query_v2(struct cros_ec_device *ec_dev)
 211 {
 212         struct cros_ec_command *msg;
 213         struct ec_params_hello *hello_params;
 214         struct ec_response_hello *hello_response;
 215         int ret;
 216         int len = max(sizeof(*hello_params), sizeof(*hello_response));
 217
 218         msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
 219         if (!msg)
 220                 return -ENOMEM;
 221
 222         msg->version = 0;
 223         msg->command = EC_CMD_HELLO;
 224         hello_params = (struct ec_params_hello *)msg->data;
 225         msg->outsize = sizeof(*hello_params);
 226         hello_response = (struct ec_response_hello *)msg->data;
 227         msg->insize = sizeof(*hello_response);
 228
 229         hello_params->in_data = 0xa0b0c0d0;
 230
 231         ret = send_command(ec_dev, msg);
 232
 233         if (ret < 0) {
 234                 dev_dbg(ec_dev->dev,
 235                         "EC failed to respond to v2 hello: %d\n",
 236                         ret);
 237                 goto exit;
 238         } else if (msg->result != EC_RES_SUCCESS) {
 239                 dev_err(ec_dev->dev,
 240                         "EC responded to v2 hello with error: %d\n",
 241                         msg->result);
 242                 ret = msg->result;
 243                 goto exit;
 244         } else if (hello_response->out_data != 0xa1b2c3d4) {
 245                 dev_err(ec_dev->dev,
 246                         "EC responded to v2 hello with bad result: %u\n",
 247                         hello_response->out_data);
 248                 ret = -EBADMSG;
 249                 goto exit;
 250         }
 251
 252         ret = 0;
 253
 254  exit:
 255         kfree(msg);
 256         return ret;
 257 }
 258
 259 int cros_ec_query_all(struct cros_ec_device *ec_dev)
 260 {
 261         struct device *dev = ec_dev->dev;
 262         struct cros_ec_command *proto_msg;
 263         struct ec_response_get_protocol_info *proto_info;
 264         int ret;
 265
 266         proto_msg = kzalloc(sizeof(*proto_msg) + sizeof(*proto_info),
 267                             GFP_KERNEL);
 268         if (!proto_msg)
 269                 return -ENOMEM;
 270
 271         /* First try sending with proto v3. */
 272         ec_dev->proto_version = 3;
 273         ret = cros_ec_host_command_proto_query(ec_dev, 0, proto_msg);
 274
 275         if (ret == 0) {
 276                 proto_info = (struct ec_response_get_protocol_info *)
 277                         proto_msg->data;
 278                 ec_dev->max_request = proto_info->max_request_packet_size -
 279                         sizeof(struct ec_host_request);
 280                 ec_dev->max_response = proto_info->max_response_packet_size -
 281                         sizeof(struct ec_host_response);
 282                 ec_dev->proto_version =
 283                         min(EC_HOST_REQUEST_VERSION,
 284                                         fls(proto_info->protocol_versions) - 1);
 285                 dev_dbg(ec_dev->dev,
 286                         "using proto v%u\n",
 287                         ec_dev->proto_version);
 288
 289                 ec_dev->din_size = ec_dev->max_response +
 290                         sizeof(struct ec_host_response) +
 291                         EC_MAX_RESPONSE_OVERHEAD;
 292                 ec_dev->dout_size = ec_dev->max_request +
 293                         sizeof(struct ec_host_request) +
 294                         EC_MAX_REQUEST_OVERHEAD;
 295
 296                 /*
 297                  * Check for PD
 298                  */
 299                 ret = cros_ec_host_command_proto_query(ec_dev, 1, proto_msg);
 300
 301                 if (ret) {
 302                         dev_dbg(ec_dev->dev, "no PD chip found: %d\n", ret);
 303                         ec_dev->max_passthru = 0;
 304                 } else {
 305                         dev_dbg(ec_dev->dev, "found PD chip\n");
 306                         ec_dev->max_passthru =
 307                                 proto_info->max_request_packet_size -
 308                                 sizeof(struct ec_host_request);
 309                 }
 310         } else {
 311                 /* Try querying with a v2 hello message. */
 312                 ec_dev->proto_version = 2;
 313                 ret = cros_ec_host_command_proto_query_v2(ec_dev);
 314
 315                 if (ret == 0) {
 316                         /* V2 hello succeeded. */
 317                         dev_dbg(ec_dev->dev, "falling back to proto v2\n");
 318
 319                         ec_dev->max_request = EC_PROTO2_MAX_PARAM_SIZE;
 320                         ec_dev->max_response = EC_PROTO2_MAX_PARAM_SIZE;
 321                         ec_dev->max_passthru = 0;
 322                         ec_dev->pkt_xfer = NULL;
 323                         ec_dev->din_size = EC_PROTO2_MSG_BYTES;
 324                         ec_dev->dout_size = EC_PROTO2_MSG_BYTES;
 325                 } else {
 326                         /*
 327                          * It's possible for a test to occur too early when
 328                          * the EC isn't listening. If this happens, we'll
 329                          * test later when the first command is run.
 330                          */
 331                         ec_dev->proto_version = EC_PROTO_VERSION_UNKNOWN;
 332                         dev_dbg(ec_dev->dev, "EC query failed: %d\n", ret);
 333                         goto exit;
 334                 }
 335         }
 336
 337         devm_kfree(dev, ec_dev->din);
 338         devm_kfree(dev, ec_dev->dout);
 339
 340         ec_dev->din = devm_kzalloc(dev, ec_dev->din_size, GFP_KERNEL);
 341         if (!ec_dev->din) {
 342                 ret = -ENOMEM;
 343                 goto exit;
 344         }
 345
 346         ec_dev->dout = devm_kzalloc(dev, ec_dev->dout_size, GFP_KERNEL);
 347         if (!ec_dev->dout) {
 348                 devm_kfree(dev, ec_dev->din);
 349                 ret = -ENOMEM;
 350                 goto exit;
 351         }
 352
 353 exit:
 354         kfree(proto_msg);
 355         return ret;
 356 }
 357 EXPORT_SYMBOL(cros_ec_query_all);
 358
 359 int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
 360                      struct cros_ec_command *msg)
 361 {
 362         int ret;
 363
 364         mutex_lock(&ec_dev->lock);
 365         if (ec_dev->proto_version == EC_PROTO_VERSION_UNKNOWN) {
 366                 ret = cros_ec_query_all(ec_dev);
 367                 if (ret) {
 368                         dev_err(ec_dev->dev,
 369                                 "EC version unknown and query failed; aborting command\n");
 370                         mutex_unlock(&ec_dev->lock);
 371                         return ret;
 372                 }
 373         }
 374
 375         if (msg->insize > ec_dev->max_response) {
 376                 dev_dbg(ec_dev->dev, "clamping message receive buffer\n");
 377                 msg->insize = ec_dev->max_response;
 378         }
 379
 380         if (msg->command < EC_CMD_PASSTHRU_OFFSET(1)) {
 381                 if (msg->outsize > ec_dev->max_request) {
 382                         dev_err(ec_dev->dev,
 383                                 "request of size %u is too big (max: %u)\n",
 384                                 msg->outsize,
 385                                 ec_dev->max_request);
 386                         mutex_unlock(&ec_dev->lock);
 387                         return -EMSGSIZE;
 388                 }
 389         } else {
 390                 if (msg->outsize > ec_dev->max_passthru) {
 391                         dev_err(ec_dev->dev,
 392                                 "passthru rq of size %u is too big (max: %u)\n",
 393                                 msg->outsize,
 394                                 ec_dev->max_passthru);
 395                         mutex_unlock(&ec_dev->lock);
 396                         return -EMSGSIZE;
 397                 }
 398         }
 399         ret = send_command(ec_dev, msg);
 400         mutex_unlock(&ec_dev->lock);
 401
 402         return ret;
 403 }
 404 EXPORT_SYMBOL(cros_ec_cmd_xfer);
 405
 406 int cros_ec_cmd_xfer_status(struct cros_ec_device *ec_dev,
 407                             struct cros_ec_command *msg)
 408 {
 409         int ret;
 410
 411         ret = cros_ec_cmd_xfer(ec_dev, msg);
 412         if (ret < 0) {
 413                 dev_err(ec_dev->dev, "Command xfer error (err:%d)\n", ret);
 414         } else if (msg->result != EC_RES_SUCCESS) {
 415                 dev_dbg(ec_dev->dev, "Command result (err: %d)\n", msg->result);
 416                 return -EPROTO;
 417         }
 418
 419         return ret;
 420 }
 421 EXPORT_SYMBOL(cros_ec_cmd_xfer_status);