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
  63         if (ec_dev->proto_version > 2)
  64                 ret = ec_dev->pkt_xfer(ec_dev, msg);
  65         else
  66                 ret = ec_dev->cmd_xfer(ec_dev, msg);
  67
  68         if (msg->result == EC_RES_IN_PROGRESS) {
  69                 int i;
  70                 struct cros_ec_command *status_msg;
  71                 struct ec_response_get_comms_status *status;
  72
  73                 status_msg = kmalloc(sizeof(*status_msg) + sizeof(*status),
  74                                      GFP_KERNEL);
  75                 if (!status_msg)
  76                         return -ENOMEM;
  77
  78                 status_msg->version = 0;
  79                 status_msg->command = EC_CMD_GET_COMMS_STATUS;
  80                 status_msg->insize = sizeof(*status);
  81                 status_msg->outsize = 0;
  82
  83                 /*
  84                  * Query the EC's status until it's no longer busy or
  85                  * we encounter an error.
  86                  */
  87                 for (i = 0; i < EC_COMMAND_RETRIES; i++) {
  88                         usleep_range(10000, 11000);
  89
  90                         ret = ec_dev->cmd_xfer(ec_dev, status_msg);
  91                         if (ret < 0)
  92                                 break;
  93
  94                         msg->result = status_msg->result;
  95                         if (status_msg->result != EC_RES_SUCCESS)
  96                                 break;
  97
  98                         status = (struct ec_response_get_comms_status *)
  99                                  status_msg->data;
 100                         if (!(status->flags & EC_COMMS_STATUS_PROCESSING))
 101                                 break;
 102                 }
 103
 104                 kfree(status_msg);
 105         }
 106
 107         return ret;
 108 }
 109
 110 int cros_ec_prepare_tx(struct cros_ec_device *ec_dev,
 111                        struct cros_ec_command *msg)
 112 {
 113         u8 *out;
 114         u8 csum;
 115         int i;
 116
 117         if (ec_dev->proto_version > 2)
 118                 return prepare_packet(ec_dev, msg);
 119
 120         BUG_ON(msg->outsize > EC_PROTO2_MAX_PARAM_SIZE);
 121         out = ec_dev->dout;
 122         out[0] = EC_CMD_VERSION0 + msg->version;
 123         out[1] = msg->command;
 124         out[2] = msg->outsize;
 125         csum = out[0] + out[1] + out[2];
 126         for (i = 0; i < msg->outsize; i++)
 127                 csum += out[EC_MSG_TX_HEADER_BYTES + i] = msg->data[i];
 128         out[EC_MSG_TX_HEADER_BYTES + msg->outsize] = csum;
 129
 130         return EC_MSG_TX_PROTO_BYTES + msg->outsize;
 131 }
 132 EXPORT_SYMBOL(cros_ec_prepare_tx);
 133
 134 int cros_ec_check_result(struct cros_ec_device *ec_dev,
 135                          struct cros_ec_command *msg)
 136 {
 137         switch (msg->result) {
 138         case EC_RES_SUCCESS:
 139                 return 0;
 140         case EC_RES_IN_PROGRESS:
 141                 dev_dbg(ec_dev->dev, "command 0x%02x in progress\n",
 142                         msg->command);
 143                 return -EAGAIN;
 144         default:
 145                 dev_dbg(ec_dev->dev, "command 0x%02x returned %d\n",
 146                         msg->command, msg->result);
 147                 return 0;
 148         }
 149 }
 150 EXPORT_SYMBOL(cros_ec_check_result);
 151
 152 static int cros_ec_host_command_proto_query(struct cros_ec_device *ec_dev,
 153                                             int devidx,
 154                                             struct cros_ec_command *msg)
 155 {
 156         /*
 157          * Try using v3+ to query for supported protocols. If this
 158          * command fails, fall back to v2. Returns the highest protocol
 159          * supported by the EC.
 160          * Also sets the max request/response/passthru size.
 161          */
 162         int ret;
 163
 164         if (!ec_dev->pkt_xfer)
 165                 return -EPROTONOSUPPORT;
 166
 167         memset(msg, 0, sizeof(*msg));
 168         msg->command = EC_CMD_PASSTHRU_OFFSET(devidx) | EC_CMD_GET_PROTOCOL_INFO;
 169         msg->insize = sizeof(struct ec_response_get_protocol_info);
 170
 171         ret = send_command(ec_dev, msg);
 172
 173         if (ret < 0) {
 174                 dev_dbg(ec_dev->dev,
 175                         "failed to check for EC[%d] protocol version: %d\n",
 176                         devidx, ret);
 177                 return ret;
 178         }
 179
 180         if (devidx > 0 && msg->result == EC_RES_INVALID_COMMAND)
 181                 return -ENODEV;
 182         else if (msg->result != EC_RES_SUCCESS)
 183                 return msg->result;
 184
 185         return 0;
 186 }
 187
 188 static int cros_ec_host_command_proto_query_v2(struct cros_ec_device *ec_dev)
 189 {
 190         struct cros_ec_command *msg;
 191         struct ec_params_hello *hello_params;
 192         struct ec_response_hello *hello_response;
 193         int ret;
 194         int len = max(sizeof(*hello_params), sizeof(*hello_response));
 195
 196         msg = kmalloc(sizeof(*msg) + len, GFP_KERNEL);
 197         if (!msg)
 198                 return -ENOMEM;
 199
 200         msg->version = 0;
 201         msg->command = EC_CMD_HELLO;
 202         hello_params = (struct ec_params_hello *)msg->data;
 203         msg->outsize = sizeof(*hello_params);
 204         hello_response = (struct ec_response_hello *)msg->data;
 205         msg->insize = sizeof(*hello_response);
 206
 207         hello_params->in_data = 0xa0b0c0d0;
 208
 209         ret = send_command(ec_dev, msg);
 210
 211         if (ret < 0) {
 212                 dev_dbg(ec_dev->dev,
 213                         "EC failed to respond to v2 hello: %d\n",
 214                         ret);
 215                 goto exit;
 216         } else if (msg->result != EC_RES_SUCCESS) {
 217                 dev_err(ec_dev->dev,
 218                         "EC responded to v2 hello with error: %d\n",
 219                         msg->result);
 220                 ret = msg->result;
 221                 goto exit;
 222         } else if (hello_response->out_data != 0xa1b2c3d4) {
 223                 dev_err(ec_dev->dev,
 224                         "EC responded to v2 hello with bad result: %u\n",
 225                         hello_response->out_data);
 226                 ret = -EBADMSG;
 227                 goto exit;
 228         }
 229
 230         ret = 0;
 231
 232  exit:
 233         kfree(msg);
 234         return ret;
 235 }
 236
 237 int cros_ec_query_all(struct cros_ec_device *ec_dev)
 238 {
 239         struct device *dev = ec_dev->dev;
 240         struct cros_ec_command *proto_msg;
 241         struct ec_response_get_protocol_info *proto_info;
 242         int ret;
 243
 244         proto_msg = kzalloc(sizeof(*proto_msg) + sizeof(*proto_info),
 245                             GFP_KERNEL);
 246         if (!proto_msg)
 247                 return -ENOMEM;
 248
 249         /* First try sending with proto v3. */
 250         ec_dev->proto_version = 3;
 251         ret = cros_ec_host_command_proto_query(ec_dev, 0, proto_msg);
 252
 253         if (ret == 0) {
 254                 proto_info = (struct ec_response_get_protocol_info *)
 255                         proto_msg->data;
 256                 ec_dev->max_request = proto_info->max_request_packet_size -
 257                         sizeof(struct ec_host_request);
 258                 ec_dev->max_response = proto_info->max_response_packet_size -
 259                         sizeof(struct ec_host_response);
 260                 ec_dev->proto_version =
 261                         min(EC_HOST_REQUEST_VERSION,
 262                                         fls(proto_info->protocol_versions) - 1);
 263                 dev_dbg(ec_dev->dev,
 264                         "using proto v%u\n",
 265                         ec_dev->proto_version);
 266
 267                 ec_dev->din_size = ec_dev->max_response +
 268                         sizeof(struct ec_host_response) +
 269                         EC_MAX_RESPONSE_OVERHEAD;
 270                 ec_dev->dout_size = ec_dev->max_request +
 271                         sizeof(struct ec_host_request) +
 272                         EC_MAX_REQUEST_OVERHEAD;
 273
 274                 /*
 275                  * Check for PD
 276                  */
 277                 ret = cros_ec_host_command_proto_query(ec_dev, 1, proto_msg);
 278
 279                 if (ret) {
 280                         dev_dbg(ec_dev->dev, "no PD chip found: %d\n", ret);
 281                         ec_dev->max_passthru = 0;
 282                 } else {
 283                         dev_dbg(ec_dev->dev, "found PD chip\n");
 284                         ec_dev->max_passthru =
 285                                 proto_info->max_request_packet_size -
 286                                 sizeof(struct ec_host_request);
 287                 }
 288         } else {
 289                 /* Try querying with a v2 hello message. */
 290                 ec_dev->proto_version = 2;
 291                 ret = cros_ec_host_command_proto_query_v2(ec_dev);
 292
 293                 if (ret == 0) {
 294                         /* V2 hello succeeded. */
 295                         dev_dbg(ec_dev->dev, "falling back to proto v2\n");
 296
 297                         ec_dev->max_request = EC_PROTO2_MAX_PARAM_SIZE;
 298                         ec_dev->max_response = EC_PROTO2_MAX_PARAM_SIZE;
 299                         ec_dev->max_passthru = 0;
 300                         ec_dev->pkt_xfer = NULL;
 301                         ec_dev->din_size = EC_PROTO2_MSG_BYTES;
 302                         ec_dev->dout_size = EC_PROTO2_MSG_BYTES;
 303                 } else {
 304                         /*
 305                          * It's possible for a test to occur too early when
 306                          * the EC isn't listening. If this happens, we'll
 307                          * test later when the first command is run.
 308                          */
 309                         ec_dev->proto_version = EC_PROTO_VERSION_UNKNOWN;
 310                         dev_dbg(ec_dev->dev, "EC query failed: %d\n", ret);
 311                         goto exit;
 312                 }
 313         }
 314
 315         devm_kfree(dev, ec_dev->din);
 316         devm_kfree(dev, ec_dev->dout);
 317
 318         ec_dev->din = devm_kzalloc(dev, ec_dev->din_size, GFP_KERNEL);
 319         if (!ec_dev->din) {
 320                 ret = -ENOMEM;
 321                 goto exit;
 322         }
 323
 324         ec_dev->dout = devm_kzalloc(dev, ec_dev->dout_size, GFP_KERNEL);
 325         if (!ec_dev->dout) {
 326                 devm_kfree(dev, ec_dev->din);
 327                 ret = -ENOMEM;
 328                 goto exit;
 329         }
 330
 331 exit:
 332         kfree(proto_msg);
 333         return ret;
 334 }
 335 EXPORT_SYMBOL(cros_ec_query_all);
 336
 337 int cros_ec_cmd_xfer(struct cros_ec_device *ec_dev,
 338                      struct cros_ec_command *msg)
 339 {
 340         int ret;
 341
 342         mutex_lock(&ec_dev->lock);
 343         if (ec_dev->proto_version == EC_PROTO_VERSION_UNKNOWN) {
 344                 ret = cros_ec_query_all(ec_dev);
 345                 if (ret) {
 346                         dev_err(ec_dev->dev,
 347                                 "EC version unknown and query failed; aborting command\n");
 348                         mutex_unlock(&ec_dev->lock);
 349                         return ret;
 350                 }
 351         }
 352
 353         if (msg->insize > ec_dev->max_response) {
 354                 dev_dbg(ec_dev->dev, "clamping message receive buffer\n");
 355                 msg->insize = ec_dev->max_response;
 356         }
 357
 358         if (msg->command < EC_CMD_PASSTHRU_OFFSET(1)) {
 359                 if (msg->outsize > ec_dev->max_request) {
 360                         dev_err(ec_dev->dev,
 361                                 "request of size %u is too big (max: %u)\n",
 362                                 msg->outsize,
 363                                 ec_dev->max_request);
 364                         mutex_unlock(&ec_dev->lock);
 365                         return -EMSGSIZE;
 366                 }
 367         } else {
 368                 if (msg->outsize > ec_dev->max_passthru) {
 369                         dev_err(ec_dev->dev,
 370                                 "passthru rq of size %u is too big (max: %u)\n",
 371                                 msg->outsize,
 372                                 ec_dev->max_passthru);
 373                         mutex_unlock(&ec_dev->lock);
 374                         return -EMSGSIZE;
 375                 }
 376         }
 377         ret = send_command(ec_dev, msg);
 378         mutex_unlock(&ec_dev->lock);
 379
 380         return ret;
 381 }
 382 EXPORT_SYMBOL(cros_ec_cmd_xfer);