drivers/platform/chrome/cros_ec_debugfs.c

   1 /*
   2  * cros_ec_debugfs - debug logs for Chrome OS EC
   3  *
   4  * Copyright 2015 Google, Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <linux/circ_buf.h>
  21 #include <linux/debugfs.h>
  22 #include <linux/delay.h>
  23 #include <linux/fs.h>
  24 #include <linux/mfd/cros_ec.h>
  25 #include <linux/mfd/cros_ec_commands.h>
  26 #include <linux/mutex.h>
  27 #include <linux/poll.h>
  28 #include <linux/sched.h>
  29 #include <linux/slab.h>
  30 #include <linux/wait.h>
  31
  32 #define LOG_SHIFT               14
  33 #define LOG_SIZE                (1 << LOG_SHIFT)
  34 #define LOG_POLL_SEC            10
  35
  36 #define CIRC_ADD(idx, size, value)      (((idx) + (value)) & ((size) - 1))
  37
  38 /* struct cros_ec_debugfs - ChromeOS EC debugging information
  39  *
  40  * @ec: EC device this debugfs information belongs to
  41  * @dir: dentry for debugfs files
  42  * @log_buffer: circular buffer for console log information
  43  * @read_msg: preallocated EC command and buffer to read console log
  44  * @log_mutex: mutex to protect circular buffer
  45  * @log_wq: waitqueue for log readers
  46  * @log_poll_work: recurring task to poll EC for new console log data
  47  * @panicinfo_blob: panicinfo debugfs blob
  48  */
  49 struct cros_ec_debugfs {
  50         struct cros_ec_dev *ec;
  51         struct dentry *dir;
  52         /* EC log */
  53         struct circ_buf log_buffer;
  54         struct cros_ec_command *read_msg;
  55         struct mutex log_mutex;
  56         wait_queue_head_t log_wq;
  57         struct delayed_work log_poll_work;
  58         /* EC panicinfo */
  59         struct debugfs_blob_wrapper panicinfo_blob;
  60 };
  61
  62 /*
  63  * We need to make sure that the EC log buffer on the UART is large enough,
  64  * so that it is unlikely enough to overlow within LOG_POLL_SEC.
  65  */
  66 static void cros_ec_console_log_work(struct work_struct *__work)
  67 {
  68         struct cros_ec_debugfs *debug_info =
  69                 container_of(to_delayed_work(__work),
  70                              struct cros_ec_debugfs,
  71                              log_poll_work);
  72         struct cros_ec_dev *ec = debug_info->ec;
  73         struct circ_buf *cb = &debug_info->log_buffer;
  74         struct cros_ec_command snapshot_msg = {
  75                 .command = EC_CMD_CONSOLE_SNAPSHOT + ec->cmd_offset,
  76         };
  77
  78         struct ec_params_console_read_v1 *read_params =
  79                 (struct ec_params_console_read_v1 *)debug_info->read_msg->data;
  80         uint8_t *ec_buffer = (uint8_t *)debug_info->read_msg->data;
  81         int idx;
  82         int buf_space;
  83         int ret;
  84
  85         ret = cros_ec_cmd_xfer(ec->ec_dev, &snapshot_msg);
  86         if (ret < 0) {
  87                 dev_err(ec->dev, "EC communication failed\n");
  88                 goto resched;
  89         }
  90         if (snapshot_msg.result != EC_RES_SUCCESS) {
  91                 dev_err(ec->dev, "EC failed to snapshot the console log\n");
  92                 goto resched;
  93         }
  94
  95         /* Loop until we have read everything, or there's an error. */
  96         mutex_lock(&debug_info->log_mutex);
  97         buf_space = CIRC_SPACE(cb->head, cb->tail, LOG_SIZE);
  98
  99         while (1) {
 100                 if (!buf_space) {
 101                         dev_info_once(ec->dev,
 102                                       "Some logs may have been dropped...\n");
 103                         break;
 104                 }
 105
 106                 memset(read_params, '\0', sizeof(*read_params));
 107                 read_params->subcmd = CONSOLE_READ_RECENT;
 108                 ret = cros_ec_cmd_xfer(ec->ec_dev, debug_info->read_msg);
 109                 if (ret < 0) {
 110                         dev_err(ec->dev, "EC communication failed\n");
 111                         break;
 112                 }
 113                 if (debug_info->read_msg->result != EC_RES_SUCCESS) {
 114                         dev_err(ec->dev,
 115                                 "EC failed to read the console log\n");
 116                         break;
 117                 }
 118
 119                 /* If the buffer is empty, we're done here. */
 120                 if (ret == 0 || ec_buffer[0] == '\0')
 121                         break;
 122
 123                 idx = 0;
 124                 while (idx < ret && ec_buffer[idx] != '\0' && buf_space > 0) {
 125                         cb->buf[cb->head] = ec_buffer[idx];
 126                         cb->head = CIRC_ADD(cb->head, LOG_SIZE, 1);
 127                         idx++;
 128                         buf_space--;
 129                 }
 130
 131                 wake_up(&debug_info->log_wq);
 132         }
 133
 134         mutex_unlock(&debug_info->log_mutex);
 135
 136 resched:
 137         schedule_delayed_work(&debug_info->log_poll_work,
 138                               msecs_to_jiffies(LOG_POLL_SEC * 1000));
 139 }
 140
 141 static int cros_ec_console_log_open(struct inode *inode, struct file *file)
 142 {
 143         file->private_data = inode->i_private;
 144
 145         return nonseekable_open(inode, file);
 146 }
 147
 148 static ssize_t cros_ec_console_log_read(struct file *file, char __user *buf,
 149                                         size_t count, loff_t *ppos)
 150 {
 151         struct cros_ec_debugfs *debug_info = file->private_data;
 152         struct circ_buf *cb = &debug_info->log_buffer;
 153         ssize_t ret;
 154
 155         mutex_lock(&debug_info->log_mutex);
 156
 157         while (!CIRC_CNT(cb->head, cb->tail, LOG_SIZE)) {
 158                 if (file->f_flags & O_NONBLOCK) {
 159                         ret = -EAGAIN;
 160                         goto error;
 161                 }
 162
 163                 mutex_unlock(&debug_info->log_mutex);
 164
 165                 ret = wait_event_interruptible(debug_info->log_wq,
 166                                         CIRC_CNT(cb->head, cb->tail, LOG_SIZE));
 167                 if (ret < 0)
 168                         return ret;
 169
 170                 mutex_lock(&debug_info->log_mutex);
 171         }
 172
 173         /* Only copy until the end of the circular buffer, and let userspace
 174          * retry to get the rest of the data.
 175          */
 176         ret = min_t(size_t, CIRC_CNT_TO_END(cb->head, cb->tail, LOG_SIZE),
 177                     count);
 178
 179         if (copy_to_user(buf, cb->buf + cb->tail, ret)) {
 180                 ret = -EFAULT;
 181                 goto error;
 182         }
 183
 184         cb->tail = CIRC_ADD(cb->tail, LOG_SIZE, ret);
 185
 186 error:
 187         mutex_unlock(&debug_info->log_mutex);
 188         return ret;
 189 }
 190
 191 static __poll_t cros_ec_console_log_poll(struct file *file,
 192                                              poll_table *wait)
 193 {
 194         struct cros_ec_debugfs *debug_info = file->private_data;
 195         __poll_t mask = 0;
 196
 197         poll_wait(file, &debug_info->log_wq, wait);
 198
 199         mutex_lock(&debug_info->log_mutex);
 200         if (CIRC_CNT(debug_info->log_buffer.head,
 201                      debug_info->log_buffer.tail,
 202                      LOG_SIZE))
 203                 mask |= EPOLLIN | EPOLLRDNORM;
 204         mutex_unlock(&debug_info->log_mutex);
 205
 206         return mask;
 207 }
 208
 209 static int cros_ec_console_log_release(struct inode *inode, struct file *file)
 210 {
 211         return 0;
 212 }
 213
 214 const struct file_operations cros_ec_console_log_fops = {
 215         .owner = THIS_MODULE,
 216         .open = cros_ec_console_log_open,
 217         .read = cros_ec_console_log_read,
 218         .llseek = no_llseek,
 219         .poll = cros_ec_console_log_poll,
 220         .release = cros_ec_console_log_release,
 221 };
 222
 223 static int ec_read_version_supported(struct cros_ec_dev *ec)
 224 {
 225         struct ec_params_get_cmd_versions_v1 *params;
 226         struct ec_response_get_cmd_versions *response;
 227         int ret;
 228
 229         struct cros_ec_command *msg;
 230
 231         msg = kzalloc(sizeof(*msg) + max(sizeof(*params), sizeof(*response)),
 232                 GFP_KERNEL);
 233         if (!msg)
 234                 return 0;
 235
 236         msg->command = EC_CMD_GET_CMD_VERSIONS + ec->cmd_offset;
 237         msg->outsize = sizeof(*params);
 238         msg->insize = sizeof(*response);
 239
 240         params = (struct ec_params_get_cmd_versions_v1 *)msg->data;
 241         params->cmd = EC_CMD_CONSOLE_READ;
 242         response = (struct ec_response_get_cmd_versions *)msg->data;
 243
 244         ret = cros_ec_cmd_xfer(ec->ec_dev, msg) >= 0 &&
 245                 msg->result == EC_RES_SUCCESS &&
 246                 (response->version_mask & EC_VER_MASK(1));
 247
 248         kfree(msg);
 249
 250         return ret;
 251 }
 252
 253 static int cros_ec_create_console_log(struct cros_ec_debugfs *debug_info)
 254 {
 255         struct cros_ec_dev *ec = debug_info->ec;
 256         char *buf;
 257         int read_params_size;
 258         int read_response_size;
 259
 260         if (!ec_read_version_supported(ec)) {
 261                 dev_warn(ec->dev,
 262                         "device does not support reading the console log\n");
 263                 return 0;
 264         }
 265
 266         buf = devm_kzalloc(ec->dev, LOG_SIZE, GFP_KERNEL);
 267         if (!buf)
 268                 return -ENOMEM;
 269
 270         read_params_size = sizeof(struct ec_params_console_read_v1);
 271         read_response_size = ec->ec_dev->max_response;
 272         debug_info->read_msg = devm_kzalloc(ec->dev,
 273                 sizeof(*debug_info->read_msg) +
 274                         max(read_params_size, read_response_size), GFP_KERNEL);
 275         if (!debug_info->read_msg)
 276                 return -ENOMEM;
 277
 278         debug_info->read_msg->version = 1;
 279         debug_info->read_msg->command = EC_CMD_CONSOLE_READ + ec->cmd_offset;
 280         debug_info->read_msg->outsize = read_params_size;
 281         debug_info->read_msg->insize = read_response_size;
 282
 283         debug_info->log_buffer.buf = buf;
 284         debug_info->log_buffer.head = 0;
 285         debug_info->log_buffer.tail = 0;
 286
 287         mutex_init(&debug_info->log_mutex);
 288         init_waitqueue_head(&debug_info->log_wq);
 289
 290         if (!debugfs_create_file("console_log",
 291                                  S_IFREG | S_IRUGO,
 292                                  debug_info->dir,
 293                                  debug_info,
 294                                  &cros_ec_console_log_fops))
 295                 return -ENOMEM;
 296
 297         INIT_DELAYED_WORK(&debug_info->log_poll_work,
 298                           cros_ec_console_log_work);
 299         schedule_delayed_work(&debug_info->log_poll_work, 0);
 300
 301         return 0;
 302 }
 303
 304 static void cros_ec_cleanup_console_log(struct cros_ec_debugfs *debug_info)
 305 {
 306         if (debug_info->log_buffer.buf) {
 307                 cancel_delayed_work_sync(&debug_info->log_poll_work);
 308                 mutex_destroy(&debug_info->log_mutex);
 309         }
 310 }
 311
 312 static int cros_ec_create_panicinfo(struct cros_ec_debugfs *debug_info)
 313 {
 314         struct cros_ec_device *ec_dev = debug_info->ec->ec_dev;
 315         int ret;
 316         struct cros_ec_command *msg;
 317         int insize;
 318
 319         insize = ec_dev->max_response;
 320
 321         msg = devm_kzalloc(debug_info->ec->dev,
 322                         sizeof(*msg) + insize, GFP_KERNEL);
 323         if (!msg)
 324                 return -ENOMEM;
 325
 326         msg->command = EC_CMD_GET_PANIC_INFO;
 327         msg->insize = insize;
 328
 329         ret = cros_ec_cmd_xfer(ec_dev, msg);
 330         if (ret < 0) {
 331                 dev_warn(debug_info->ec->dev, "Cannot read panicinfo.\n");
 332                 ret = 0;
 333                 goto free;
 334         }
 335
 336         /* No panic data */
 337         if (ret == 0)
 338                 goto free;
 339
 340         debug_info->panicinfo_blob.data = msg->data;
 341         debug_info->panicinfo_blob.size = ret;
 342
 343         if (!debugfs_create_blob("panicinfo",
 344                                  S_IFREG | S_IRUGO,
 345                                  debug_info->dir,
 346                                  &debug_info->panicinfo_blob)) {
 347                 ret = -ENOMEM;
 348                 goto free;
 349         }
 350
 351         return 0;
 352
 353 free:
 354         devm_kfree(debug_info->ec->dev, msg);
 355         return ret;
 356 }
 357
 358 int cros_ec_debugfs_init(struct cros_ec_dev *ec)
 359 {
 360         struct cros_ec_platform *ec_platform = dev_get_platdata(ec->dev);
 361         const char *name = ec_platform->ec_name;
 362         struct cros_ec_debugfs *debug_info;
 363         int ret;
 364
 365         debug_info = devm_kzalloc(ec->dev, sizeof(*debug_info), GFP_KERNEL);
 366         if (!debug_info)
 367                 return -ENOMEM;
 368
 369         debug_info->ec = ec;
 370         debug_info->dir = debugfs_create_dir(name, NULL);
 371         if (!debug_info->dir)
 372                 return -ENOMEM;
 373
 374         ret = cros_ec_create_panicinfo(debug_info);
 375         if (ret)
 376                 goto remove_debugfs;
 377
 378         ret = cros_ec_create_console_log(debug_info);
 379         if (ret)
 380                 goto remove_debugfs;
 381
 382         ec->debug_info = debug_info;
 383
 384         return 0;
 385
 386 remove_debugfs:
 387         debugfs_remove_recursive(debug_info->dir);
 388         return ret;
 389 }
 390 EXPORT_SYMBOL(cros_ec_debugfs_init);
 391
 392 void cros_ec_debugfs_remove(struct cros_ec_dev *ec)
 393 {
 394         if (!ec->debug_info)
 395                 return;
 396
 397         debugfs_remove_recursive(ec->debug_info->dir);
 398         cros_ec_cleanup_console_log(ec->debug_info);
 399 }
 400 EXPORT_SYMBOL(cros_ec_debugfs_remove);