drivers/base/regmap/regmap-debugfs.c

   1 /*
   2  * Register map access API - debugfs
   3  *
   4  * Copyright 2011 Wolfson Microelectronics plc
   5  *
   6  * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/slab.h>
  14 #include <linux/mutex.h>
  15 #include <linux/debugfs.h>
  16 #include <linux/uaccess.h>
  17 #include <linux/device.h>
  18 #include <linux/list.h>
  19
  20 #include "internal.h"
  21
  22 struct regmap_debugfs_node {
  23         struct regmap *map;
  24         const char *name;
  25         struct list_head link;
  26 };
  27
  28 static struct dentry *regmap_debugfs_root;
  29 static LIST_HEAD(regmap_debugfs_early_list);
  30 static DEFINE_MUTEX(regmap_debugfs_early_lock);
  31
  32 /* Calculate the length of a fixed format  */
  33 static size_t regmap_calc_reg_len(int max_val)
  34 {
  35         return snprintf(NULL, 0, "%x", max_val);
  36 }
  37
  38 static ssize_t regmap_name_read_file(struct file *file,
  39                                      char __user *user_buf, size_t count,
  40                                      loff_t *ppos)
  41 {
  42         struct regmap *map = file->private_data;
  43         int ret;
  44         char *buf;
  45
  46         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
  47         if (!buf)
  48                 return -ENOMEM;
  49
  50         ret = snprintf(buf, PAGE_SIZE, "%s\n", map->dev->driver->name);
  51         if (ret < 0) {
  52                 kfree(buf);
  53                 return ret;
  54         }
  55
  56         ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
  57         kfree(buf);
  58         return ret;
  59 }
  60
  61 static const struct file_operations regmap_name_fops = {
  62         .open = simple_open,
  63         .read = regmap_name_read_file,
  64         .llseek = default_llseek,
  65 };
  66
  67 static void regmap_debugfs_free_dump_cache(struct regmap *map)
  68 {
  69         struct regmap_debugfs_off_cache *c;
  70
  71         while (!list_empty(&map->debugfs_off_cache)) {
  72                 c = list_first_entry(&map->debugfs_off_cache,
  73                                      struct regmap_debugfs_off_cache,
  74                                      list);
  75                 list_del(&c->list);
  76                 kfree(c);
  77         }
  78 }
  79
  80 static bool regmap_printable(struct regmap *map, unsigned int reg)
  81 {
  82         if (regmap_precious(map, reg))
  83                 return false;
  84
  85         if (!regmap_readable(map, reg) && !regmap_cached(map, reg))
  86                 return false;
  87
  88         return true;
  89 }
  90
  91 /*
  92  * Work out where the start offset maps into register numbers, bearing
  93  * in mind that we suppress hidden registers.
  94  */
  95 static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
  96                                                   unsigned int base,
  97                                                   loff_t from,
  98                                                   loff_t *pos)
  99 {
 100         struct regmap_debugfs_off_cache *c = NULL;
 101         loff_t p = 0;
 102         unsigned int i, ret;
 103         unsigned int fpos_offset;
 104         unsigned int reg_offset;
 105
 106         /* Suppress the cache if we're using a subrange */
 107         if (base)
 108                 return base;
 109
 110         /*
 111          * If we don't have a cache build one so we don't have to do a
 112          * linear scan each time.
 113          */
 114         mutex_lock(&map->cache_lock);
 115         i = base;
 116         if (list_empty(&map->debugfs_off_cache)) {
 117                 for (; i <= map->max_register; i += map->reg_stride) {
 118                         /* Skip unprinted registers, closing off cache entry */
 119                         if (!regmap_printable(map, i)) {
 120                                 if (c) {
 121                                         c->max = p - 1;
 122                                         c->max_reg = i - map->reg_stride;
 123                                         list_add_tail(&c->list,
 124                                                       &map->debugfs_off_cache);
 125                                         c = NULL;
 126                                 }
 127
 128                                 continue;
 129                         }
 130
 131                         /* No cache entry?  Start a new one */
 132                         if (!c) {
 133                                 c = kzalloc(sizeof(*c), GFP_KERNEL);
 134                                 if (!c) {
 135                                         regmap_debugfs_free_dump_cache(map);
 136                                         mutex_unlock(&map->cache_lock);
 137                                         return base;
 138                                 }
 139                                 c->min = p;
 140                                 c->base_reg = i;
 141                         }
 142
 143                         p += map->debugfs_tot_len;
 144                 }
 145         }
 146
 147         /* Close the last entry off if we didn't scan beyond it */
 148         if (c) {
 149                 c->max = p - 1;
 150                 c->max_reg = i - map->reg_stride;
 151                 list_add_tail(&c->list,
 152                               &map->debugfs_off_cache);
 153         }
 154
 155         /*
 156          * This should never happen; we return above if we fail to
 157          * allocate and we should never be in this code if there are
 158          * no registers at all.
 159          */
 160         WARN_ON(list_empty(&map->debugfs_off_cache));
 161         ret = base;
 162
 163         /* Find the relevant block:offset */
 164         list_for_each_entry(c, &map->debugfs_off_cache, list) {
 165                 if (from >= c->min && from <= c->max) {
 166                         fpos_offset = from - c->min;
 167                         reg_offset = fpos_offset / map->debugfs_tot_len;
 168                         *pos = c->min + (reg_offset * map->debugfs_tot_len);
 169                         mutex_unlock(&map->cache_lock);
 170                         return c->base_reg + (reg_offset * map->reg_stride);
 171                 }
 172
 173                 *pos = c->max;
 174                 ret = c->max_reg;
 175         }
 176         mutex_unlock(&map->cache_lock);
 177
 178         return ret;
 179 }
 180
 181 static inline void regmap_calc_tot_len(struct regmap *map,
 182                                        void *buf, size_t count)
 183 {
 184         /* Calculate the length of a fixed format  */
 185         if (!map->debugfs_tot_len) {
 186                 map->debugfs_reg_len = regmap_calc_reg_len(map->max_register),
 187                 map->debugfs_val_len = 2 * map->format.val_bytes;
 188                 map->debugfs_tot_len = map->debugfs_reg_len +
 189                         map->debugfs_val_len + 3;      /* : \n */
 190         }
 191 }
 192
 193 static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
 194                                    unsigned int to, char __user *user_buf,
 195                                    size_t count, loff_t *ppos)
 196 {
 197         size_t buf_pos = 0;
 198         loff_t p = *ppos;
 199         ssize_t ret;
 200         int i;
 201         char *buf;
 202         unsigned int val, start_reg;
 203
 204         if (*ppos < 0 || !count)
 205                 return -EINVAL;
 206
 207         buf = kmalloc(count, GFP_KERNEL);
 208         if (!buf)
 209                 return -ENOMEM;
 210
 211         regmap_calc_tot_len(map, buf, count);
 212
 213         /* Work out which register we're starting at */
 214         start_reg = regmap_debugfs_get_dump_start(map, from, *ppos, &p);
 215
 216         for (i = start_reg; i <= to; i += map->reg_stride) {
 217                 if (!regmap_readable(map, i) && !regmap_cached(map, i))
 218                         continue;
 219
 220                 if (regmap_precious(map, i))
 221                         continue;
 222
 223                 /* If we're in the region the user is trying to read */
 224                 if (p >= *ppos) {
 225                         /* ...but not beyond it */
 226                         if (buf_pos + map->debugfs_tot_len > count)
 227                                 break;
 228
 229                         /* Format the register */
 230                         snprintf(buf + buf_pos, count - buf_pos, "%.*x: ",
 231                                  map->debugfs_reg_len, i - from);
 232                         buf_pos += map->debugfs_reg_len + 2;
 233
 234                         /* Format the value, write all X if we can't read */
 235                         ret = regmap_read(map, i, &val);
 236                         if (ret == 0)
 237                                 snprintf(buf + buf_pos, count - buf_pos,
 238                                          "%.*x", map->debugfs_val_len, val);
 239                         else
 240                                 memset(buf + buf_pos, 'X',
 241                                        map->debugfs_val_len);
 242                         buf_pos += 2 * map->format.val_bytes;
 243
 244                         buf[buf_pos++] = '\n';
 245                 }
 246                 p += map->debugfs_tot_len;
 247         }
 248
 249         ret = buf_pos;
 250
 251         if (copy_to_user(user_buf, buf, buf_pos)) {
 252                 ret = -EFAULT;
 253                 goto out;
 254         }
 255
 256         *ppos += buf_pos;
 257
 258 out:
 259         kfree(buf);
 260         return ret;
 261 }
 262
 263 static ssize_t regmap_map_read_file(struct file *file, char __user *user_buf,
 264                                     size_t count, loff_t *ppos)
 265 {
 266         struct regmap *map = file->private_data;
 267
 268         return regmap_read_debugfs(map, 0, map->max_register, user_buf,
 269                                    count, ppos);
 270 }
 271
 272 #undef REGMAP_ALLOW_WRITE_DEBUGFS
 273 #ifdef REGMAP_ALLOW_WRITE_DEBUGFS
 274 /*
 275  * This can be dangerous especially when we have clients such as
 276  * PMICs, therefore don't provide any real compile time configuration option
 277  * for this feature, people who want to use this will need to modify
 278  * the source code directly.
 279  */
 280 static ssize_t regmap_map_write_file(struct file *file,
 281                                      const char __user *user_buf,
 282                                      size_t count, loff_t *ppos)
 283 {
 284         char buf[32];
 285         size_t buf_size;
 286         char *start = buf;
 287         unsigned long reg, value;
 288         struct regmap *map = file->private_data;
 289         int ret;
 290
 291         buf_size = min(count, (sizeof(buf)-1));
 292         if (copy_from_user(buf, user_buf, buf_size))
 293                 return -EFAULT;
 294         buf[buf_size] = 0;
 295
 296         while (*start == ' ')
 297                 start++;
 298         reg = simple_strtoul(start, &start, 16);
 299         while (*start == ' ')
 300                 start++;
 301         if (kstrtoul(start, 16, &value))
 302                 return -EINVAL;
 303
 304         /* Userspace has been fiddling around behind the kernel's back */
 305         add_taint(TAINT_USER, LOCKDEP_STILL_OK);
 306
 307         ret = regmap_write(map, reg, value);
 308         if (ret < 0)
 309                 return ret;
 310         return buf_size;
 311 }
 312 #else
 313 #define regmap_map_write_file NULL
 314 #endif
 315
 316 static const struct file_operations regmap_map_fops = {
 317         .open = simple_open,
 318         .read = regmap_map_read_file,
 319         .write = regmap_map_write_file,
 320         .llseek = default_llseek,
 321 };
 322
 323 static ssize_t regmap_range_read_file(struct file *file, char __user *user_buf,
 324                                       size_t count, loff_t *ppos)
 325 {
 326         struct regmap_range_node *range = file->private_data;
 327         struct regmap *map = range->map;
 328
 329         return regmap_read_debugfs(map, range->range_min, range->range_max,
 330                                    user_buf, count, ppos);
 331 }
 332
 333 static const struct file_operations regmap_range_fops = {
 334         .open = simple_open,
 335         .read = regmap_range_read_file,
 336         .llseek = default_llseek,
 337 };
 338
 339 static ssize_t regmap_reg_ranges_read_file(struct file *file,
 340                                            char __user *user_buf, size_t count,
 341                                            loff_t *ppos)
 342 {
 343         struct regmap *map = file->private_data;
 344         struct regmap_debugfs_off_cache *c;
 345         loff_t p = 0;
 346         size_t buf_pos = 0;
 347         char *buf;
 348         char *entry;
 349         int ret;
 350         unsigned entry_len;
 351
 352         if (*ppos < 0 || !count)
 353                 return -EINVAL;
 354
 355         buf = kmalloc(count, GFP_KERNEL);
 356         if (!buf)
 357                 return -ENOMEM;
 358
 359         entry = kmalloc(PAGE_SIZE, GFP_KERNEL);
 360         if (!entry) {
 361                 kfree(buf);
 362                 return -ENOMEM;
 363         }
 364
 365         /* While we are at it, build the register dump cache
 366          * now so the read() operation on the `registers' file
 367          * can benefit from using the cache.  We do not care
 368          * about the file position information that is contained
 369          * in the cache, just about the actual register blocks */
 370         regmap_calc_tot_len(map, buf, count);
 371         regmap_debugfs_get_dump_start(map, 0, *ppos, &p);
 372
 373         /* Reset file pointer as the fixed-format of the `registers'
 374          * file is not compatible with the `range' file */
 375         p = 0;
 376         mutex_lock(&map->cache_lock);
 377         list_for_each_entry(c, &map->debugfs_off_cache, list) {
 378                 entry_len = snprintf(entry, PAGE_SIZE, "%x-%x\n",
 379                                      c->base_reg, c->max_reg);
 380                 if (p >= *ppos) {
 381                         if (buf_pos + entry_len > count)
 382                                 break;
 383                         memcpy(buf + buf_pos, entry, entry_len);
 384                         buf_pos += entry_len;
 385                 }
 386                 p += entry_len;
 387         }
 388         mutex_unlock(&map->cache_lock);
 389
 390         kfree(entry);
 391         ret = buf_pos;
 392
 393         if (copy_to_user(user_buf, buf, buf_pos)) {
 394                 ret = -EFAULT;
 395                 goto out_buf;
 396         }
 397
 398         *ppos += buf_pos;
 399 out_buf:
 400         kfree(buf);
 401         return ret;
 402 }
 403
 404 static const struct file_operations regmap_reg_ranges_fops = {
 405         .open = simple_open,
 406         .read = regmap_reg_ranges_read_file,
 407         .llseek = default_llseek,
 408 };
 409
 410 static int regmap_access_show(struct seq_file *s, void *ignored)
 411 {
 412         struct regmap *map = s->private;
 413         int i, reg_len;
 414
 415         reg_len = regmap_calc_reg_len(map->max_register);
 416
 417         for (i = 0; i <= map->max_register; i += map->reg_stride) {
 418                 /* Ignore registers which are neither readable nor writable */
 419                 if (!regmap_readable(map, i) && !regmap_writeable(map, i))
 420                         continue;
 421
 422                 /* Format the register */
 423                 seq_printf(s, "%.*x: %c %c %c %c\n", reg_len, i,
 424                            regmap_readable(map, i) ? 'y' : 'n',
 425                            regmap_writeable(map, i) ? 'y' : 'n',
 426                            regmap_volatile(map, i) ? 'y' : 'n',
 427                            regmap_precious(map, i) ? 'y' : 'n');
 428         }
 429
 430         return 0;
 431 }
 432
 433 static int access_open(struct inode *inode, struct file *file)
 434 {
 435         return single_open(file, regmap_access_show, inode->i_private);
 436 }
 437
 438 static const struct file_operations regmap_access_fops = {
 439         .open           = access_open,
 440         .read           = seq_read,
 441         .llseek         = seq_lseek,
 442         .release        = single_release,
 443 };
 444
 445 static ssize_t regmap_cache_only_write_file(struct file *file,
 446                                             const char __user *user_buf,
 447                                             size_t count, loff_t *ppos)
 448 {
 449         struct regmap *map = container_of(file->private_data,
 450                                           struct regmap, cache_only);
 451         ssize_t result;
 452         bool was_enabled, require_sync = false;
 453         int err;
 454
 455         map->lock(map->lock_arg);
 456
 457         was_enabled = map->cache_only;
 458
 459         result = debugfs_write_file_bool(file, user_buf, count, ppos);
 460         if (result < 0) {
 461                 map->unlock(map->lock_arg);
 462                 return result;
 463         }
 464
 465         if (map->cache_only && !was_enabled) {
 466                 dev_warn(map->dev, "debugfs cache_only=Y forced\n");
 467                 add_taint(TAINT_USER, LOCKDEP_STILL_OK);
 468         } else if (!map->cache_only && was_enabled) {
 469                 dev_warn(map->dev, "debugfs cache_only=N forced: syncing cache\n");
 470                 require_sync = true;
 471         }
 472
 473         map->unlock(map->lock_arg);
 474
 475         if (require_sync) {
 476                 err = regcache_sync(map);
 477                 if (err)
 478                         dev_err(map->dev, "Failed to sync cache %d\n", err);
 479         }
 480
 481         return result;
 482 }
 483
 484 static const struct file_operations regmap_cache_only_fops = {
 485         .open = simple_open,
 486         .read = debugfs_read_file_bool,
 487         .write = regmap_cache_only_write_file,
 488 };
 489
 490 static ssize_t regmap_cache_bypass_write_file(struct file *file,
 491                                               const char __user *user_buf,
 492                                               size_t count, loff_t *ppos)
 493 {
 494         struct regmap *map = container_of(file->private_data,
 495                                           struct regmap, cache_bypass);
 496         ssize_t result;
 497         bool was_enabled;
 498
 499         map->lock(map->lock_arg);
 500
 501         was_enabled = map->cache_bypass;
 502
 503         result = debugfs_write_file_bool(file, user_buf, count, ppos);
 504         if (result < 0)
 505                 goto out;
 506
 507         if (map->cache_bypass && !was_enabled) {
 508                 dev_warn(map->dev, "debugfs cache_bypass=Y forced\n");
 509                 add_taint(TAINT_USER, LOCKDEP_STILL_OK);
 510         } else if (!map->cache_bypass && was_enabled) {
 511                 dev_warn(map->dev, "debugfs cache_bypass=N forced\n");
 512         }
 513
 514 out:
 515         map->unlock(map->lock_arg);
 516
 517         return result;
 518 }
 519
 520 static const struct file_operations regmap_cache_bypass_fops = {
 521         .open = simple_open,
 522         .read = debugfs_read_file_bool,
 523         .write = regmap_cache_bypass_write_file,
 524 };
 525
 526 void regmap_debugfs_init(struct regmap *map, const char *name)
 527 {
 528         struct rb_node *next;
 529         struct regmap_range_node *range_node;
 530         const char *devname = "dummy";
 531
 532         /*
 533          * Userspace can initiate reads from the hardware over debugfs.
 534          * Normally internal regmap structures and buffers are protected with
 535          * a mutex or a spinlock, but if the regmap owner decided to disable
 536          * all locking mechanisms, this is no longer the case. For safety:
 537          * don't create the debugfs entries if locking is disabled.
 538          */
 539         if (map->debugfs_disable) {
 540                 dev_dbg(map->dev, "regmap locking disabled - not creating debugfs entries\n");
 541                 return;
 542         }
 543
 544         /* If we don't have the debugfs root yet, postpone init */
 545         if (!regmap_debugfs_root) {
 546                 struct regmap_debugfs_node *node;
 547                 node = kzalloc(sizeof(*node), GFP_KERNEL);
 548                 if (!node)
 549                         return;
 550                 node->map = map;
 551                 node->name = name;
 552                 mutex_lock(&regmap_debugfs_early_lock);
 553                 list_add(&node->link, &regmap_debugfs_early_list);
 554                 mutex_unlock(&regmap_debugfs_early_lock);
 555                 return;
 556         }
 557
 558         INIT_LIST_HEAD(&map->debugfs_off_cache);
 559         mutex_init(&map->cache_lock);
 560
 561         if (map->dev)
 562                 devname = dev_name(map->dev);
 563
 564         if (name) {
 565                 map->debugfs_name = kasprintf(GFP_KERNEL, "%s-%s",
 566                                               devname, name);
 567                 name = map->debugfs_name;
 568         } else {
 569                 name = devname;
 570         }
 571
 572         map->debugfs = debugfs_create_dir(name, regmap_debugfs_root);
 573         if (!map->debugfs) {
 574                 dev_warn(map->dev, "Failed to create debugfs directory\n");
 575                 return;
 576         }
 577
 578         debugfs_create_file("name", 0400, map->debugfs,
 579                             map, &regmap_name_fops);
 580
 581         debugfs_create_file("range", 0400, map->debugfs,
 582                             map, &regmap_reg_ranges_fops);
 583
 584         if (map->max_register || regmap_readable(map, 0)) {
 585                 umode_t registers_mode;
 586
 587 #if defined(REGMAP_ALLOW_WRITE_DEBUGFS)
 588                 registers_mode = 0600;
 589 #else
 590                 registers_mode = 0400;
 591 #endif
 592
 593                 debugfs_create_file("registers", registers_mode, map->debugfs,
 594                                     map, &regmap_map_fops);
 595                 debugfs_create_file("access", 0400, map->debugfs,
 596                                     map, &regmap_access_fops);
 597         }
 598
 599         if (map->cache_type) {
 600                 debugfs_create_file("cache_only", 0600, map->debugfs,
 601                                     &map->cache_only, &regmap_cache_only_fops);
 602                 debugfs_create_bool("cache_dirty", 0400, map->debugfs,
 603                                     &map->cache_dirty);
 604                 debugfs_create_file("cache_bypass", 0600, map->debugfs,
 605                                     &map->cache_bypass,
 606                                     &regmap_cache_bypass_fops);
 607         }
 608
 609         next = rb_first(&map->range_tree);
 610         while (next) {
 611                 range_node = rb_entry(next, struct regmap_range_node, node);
 612
 613                 if (range_node->name)
 614                         debugfs_create_file(range_node->name, 0400,
 615                                             map->debugfs, range_node,
 616                                             &regmap_range_fops);
 617
 618                 next = rb_next(&range_node->node);
 619         }
 620
 621         if (map->cache_ops && map->cache_ops->debugfs_init)
 622                 map->cache_ops->debugfs_init(map);
 623 }
 624
 625 void regmap_debugfs_exit(struct regmap *map)
 626 {
 627         if (map->debugfs) {
 628                 debugfs_remove_recursive(map->debugfs);
 629                 mutex_lock(&map->cache_lock);
 630                 regmap_debugfs_free_dump_cache(map);
 631                 mutex_unlock(&map->cache_lock);
 632                 kfree(map->debugfs_name);
 633         } else {
 634                 struct regmap_debugfs_node *node, *tmp;
 635
 636                 mutex_lock(&regmap_debugfs_early_lock);
 637                 list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list,
 638                                          link) {
 639                         if (node->map == map) {
 640                                 list_del(&node->link);
 641                                 kfree(node);
 642                         }
 643                 }
 644                 mutex_unlock(&regmap_debugfs_early_lock);
 645         }
 646 }
 647
 648 void regmap_debugfs_initcall(void)
 649 {
 650         struct regmap_debugfs_node *node, *tmp;
 651
 652         regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
 653         if (!regmap_debugfs_root) {
 654                 pr_warn("regmap: Failed to create debugfs root\n");
 655                 return;
 656         }
 657
 658         mutex_lock(&regmap_debugfs_early_lock);
 659         list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list, link) {
 660                 regmap_debugfs_init(node->map, node->name);
 661                 list_del(&node->link);
 662                 kfree(node);
 663         }
 664         mutex_unlock(&regmap_debugfs_early_lock);
 665 }