drivers/base/regmap/regmap-debugfs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 //
   3 // Register map access API - debugfs
   4 //
   5 // Copyright 2011 Wolfson Microelectronics plc
   6 //
   7 // Author: Mark Brown <[email protected]>
   8
   9 #include <linux/slab.h>
  10 #include <linux/mutex.h>
  11 #include <linux/debugfs.h>
  12 #include <linux/uaccess.h>
  13 #include <linux/device.h>
  14 #include <linux/list.h>
  15
  16 #include "internal.h"
  17
  18 struct regmap_debugfs_node {
  19         struct regmap *map;
  20         struct list_head link;
  21 };
  22
  23 static unsigned int dummy_index;
  24 static struct dentry *regmap_debugfs_root;
  25 static LIST_HEAD(regmap_debugfs_early_list);
  26 static DEFINE_MUTEX(regmap_debugfs_early_lock);
  27
  28 /* Calculate the length of a fixed format  */
  29 static size_t regmap_calc_reg_len(int max_val)
  30 {
  31         return snprintf(NULL, 0, "%x", max_val);
  32 }
  33
  34 static ssize_t regmap_name_read_file(struct file *file,
  35                                      char __user *user_buf, size_t count,
  36                                      loff_t *ppos)
  37 {
  38         struct regmap *map = file->private_data;
  39         const char *name = "nodev";
  40         int ret;
  41         char *buf;
  42
  43         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
  44         if (!buf)
  45                 return -ENOMEM;
  46
  47         if (map->dev && map->dev->driver)
  48                 name = map->dev->driver->name;
  49
  50         ret = snprintf(buf, PAGE_SIZE, "%s\n", 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 int regmap_next_readable_reg(struct regmap *map, int reg)
 194 {
 195         struct regmap_debugfs_off_cache *c;
 196         int ret = -EINVAL;
 197
 198         if (regmap_printable(map, reg + map->reg_stride)) {
 199                 ret = reg + map->reg_stride;
 200         } else {
 201                 mutex_lock(&map->cache_lock);
 202                 list_for_each_entry(c, &map->debugfs_off_cache, list) {
 203                         if (reg > c->max_reg)
 204                                 continue;
 205                         if (reg < c->base_reg) {
 206                                 ret = c->base_reg;
 207                                 break;
 208                         }
 209                 }
 210                 mutex_unlock(&map->cache_lock);
 211         }
 212         return ret;
 213 }
 214
 215 static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
 216                                    unsigned int to, char __user *user_buf,
 217                                    size_t count, loff_t *ppos)
 218 {
 219         size_t buf_pos = 0;
 220         loff_t p = *ppos;
 221         ssize_t ret;
 222         int i;
 223         char *buf;
 224         unsigned int val, start_reg;
 225
 226         if (*ppos < 0 || !count)
 227                 return -EINVAL;
 228
 229         if (count > (PAGE_SIZE << MAX_ORDER))
 230                 count = PAGE_SIZE << MAX_ORDER;
 231
 232         buf = kmalloc(count, GFP_KERNEL);
 233         if (!buf)
 234                 return -ENOMEM;
 235
 236         regmap_calc_tot_len(map, buf, count);
 237
 238         /* Work out which register we're starting at */
 239         start_reg = regmap_debugfs_get_dump_start(map, from, *ppos, &p);
 240
 241         for (i = start_reg; i >= 0 && i <= to;
 242              i = regmap_next_readable_reg(map, i)) {
 243
 244                 /* If we're in the region the user is trying to read */
 245                 if (p >= *ppos) {
 246                         /* ...but not beyond it */
 247                         if (buf_pos + map->debugfs_tot_len > count)
 248                                 break;
 249
 250                         /* Format the register */
 251                         snprintf(buf + buf_pos, count - buf_pos, "%.*x: ",
 252                                  map->debugfs_reg_len, i - from);
 253                         buf_pos += map->debugfs_reg_len + 2;
 254
 255                         /* Format the value, write all X if we can't read */
 256                         ret = regmap_read(map, i, &val);
 257                         if (ret == 0)
 258                                 snprintf(buf + buf_pos, count - buf_pos,
 259                                          "%.*x", map->debugfs_val_len, val);
 260                         else
 261                                 memset(buf + buf_pos, 'X',
 262                                        map->debugfs_val_len);
 263                         buf_pos += 2 * map->format.val_bytes;
 264
 265                         buf[buf_pos++] = '\n';
 266                 }
 267                 p += map->debugfs_tot_len;
 268         }
 269
 270         ret = buf_pos;
 271
 272         if (copy_to_user(user_buf, buf, buf_pos)) {
 273                 ret = -EFAULT;
 274                 goto out;
 275         }
 276
 277         *ppos += buf_pos;
 278
 279 out:
 280         kfree(buf);
 281         return ret;
 282 }
 283
 284 static ssize_t regmap_map_read_file(struct file *file, char __user *user_buf,
 285                                     size_t count, loff_t *ppos)
 286 {
 287         struct regmap *map = file->private_data;
 288
 289         return regmap_read_debugfs(map, 0, map->max_register, user_buf,
 290                                    count, ppos);
 291 }
 292
 293 #undef REGMAP_ALLOW_WRITE_DEBUGFS
 294 #ifdef REGMAP_ALLOW_WRITE_DEBUGFS
 295 /*
 296  * This can be dangerous especially when we have clients such as
 297  * PMICs, therefore don't provide any real compile time configuration option
 298  * for this feature, people who want to use this will need to modify
 299  * the source code directly.
 300  */
 301 static ssize_t regmap_map_write_file(struct file *file,
 302                                      const char __user *user_buf,
 303                                      size_t count, loff_t *ppos)
 304 {
 305         char buf[32];
 306         size_t buf_size;
 307         char *start = buf;
 308         unsigned long reg, value;
 309         struct regmap *map = file->private_data;
 310         int ret;
 311
 312         buf_size = min(count, (sizeof(buf)-1));
 313         if (copy_from_user(buf, user_buf, buf_size))
 314                 return -EFAULT;
 315         buf[buf_size] = 0;
 316
 317         while (*start == ' ')
 318                 start++;
 319         reg = simple_strtoul(start, &start, 16);
 320         while (*start == ' ')
 321                 start++;
 322         if (kstrtoul(start, 16, &value))
 323                 return -EINVAL;
 324
 325         /* Userspace has been fiddling around behind the kernel's back */
 326         add_taint(TAINT_USER, LOCKDEP_STILL_OK);
 327
 328         ret = regmap_write(map, reg, value);
 329         if (ret < 0)
 330                 return ret;
 331         return buf_size;
 332 }
 333 #else
 334 #define regmap_map_write_file NULL
 335 #endif
 336
 337 static const struct file_operations regmap_map_fops = {
 338         .open = simple_open,
 339         .read = regmap_map_read_file,
 340         .write = regmap_map_write_file,
 341         .llseek = default_llseek,
 342 };
 343
 344 static ssize_t regmap_range_read_file(struct file *file, char __user *user_buf,
 345                                       size_t count, loff_t *ppos)
 346 {
 347         struct regmap_range_node *range = file->private_data;
 348         struct regmap *map = range->map;
 349
 350         return regmap_read_debugfs(map, range->range_min, range->range_max,
 351                                    user_buf, count, ppos);
 352 }
 353
 354 static const struct file_operations regmap_range_fops = {
 355         .open = simple_open,
 356         .read = regmap_range_read_file,
 357         .llseek = default_llseek,
 358 };
 359
 360 static ssize_t regmap_reg_ranges_read_file(struct file *file,
 361                                            char __user *user_buf, size_t count,
 362                                            loff_t *ppos)
 363 {
 364         struct regmap *map = file->private_data;
 365         struct regmap_debugfs_off_cache *c;
 366         loff_t p = 0;
 367         size_t buf_pos = 0;
 368         char *buf;
 369         char *entry;
 370         int ret;
 371         unsigned int entry_len;
 372
 373         if (*ppos < 0 || !count)
 374                 return -EINVAL;
 375
 376         if (count > (PAGE_SIZE << MAX_ORDER))
 377                 count = PAGE_SIZE << MAX_ORDER;
 378
 379         buf = kmalloc(count, GFP_KERNEL);
 380         if (!buf)
 381                 return -ENOMEM;
 382
 383         entry = kmalloc(PAGE_SIZE, GFP_KERNEL);
 384         if (!entry) {
 385                 kfree(buf);
 386                 return -ENOMEM;
 387         }
 388
 389         /* While we are at it, build the register dump cache
 390          * now so the read() operation on the `registers' file
 391          * can benefit from using the cache.  We do not care
 392          * about the file position information that is contained
 393          * in the cache, just about the actual register blocks */
 394         regmap_calc_tot_len(map, buf, count);
 395         regmap_debugfs_get_dump_start(map, 0, *ppos, &p);
 396
 397         /* Reset file pointer as the fixed-format of the `registers'
 398          * file is not compatible with the `range' file */
 399         p = 0;
 400         mutex_lock(&map->cache_lock);
 401         list_for_each_entry(c, &map->debugfs_off_cache, list) {
 402                 entry_len = snprintf(entry, PAGE_SIZE, "%x-%x\n",
 403                                      c->base_reg, c->max_reg);
 404                 if (p >= *ppos) {
 405                         if (buf_pos + entry_len > count)
 406                                 break;
 407                         memcpy(buf + buf_pos, entry, entry_len);
 408                         buf_pos += entry_len;
 409                 }
 410                 p += entry_len;
 411         }
 412         mutex_unlock(&map->cache_lock);
 413
 414         kfree(entry);
 415         ret = buf_pos;
 416
 417         if (copy_to_user(user_buf, buf, buf_pos)) {
 418                 ret = -EFAULT;
 419                 goto out_buf;
 420         }
 421
 422         *ppos += buf_pos;
 423 out_buf:
 424         kfree(buf);
 425         return ret;
 426 }
 427
 428 static const struct file_operations regmap_reg_ranges_fops = {
 429         .open = simple_open,
 430         .read = regmap_reg_ranges_read_file,
 431         .llseek = default_llseek,
 432 };
 433
 434 static int regmap_access_show(struct seq_file *s, void *ignored)
 435 {
 436         struct regmap *map = s->private;
 437         int i, reg_len;
 438
 439         reg_len = regmap_calc_reg_len(map->max_register);
 440
 441         for (i = 0; i <= map->max_register; i += map->reg_stride) {
 442                 /* Ignore registers which are neither readable nor writable */
 443                 if (!regmap_readable(map, i) && !regmap_writeable(map, i))
 444                         continue;
 445
 446                 /* Format the register */
 447                 seq_printf(s, "%.*x: %c %c %c %c\n", reg_len, i,
 448                            regmap_readable(map, i) ? 'y' : 'n',
 449                            regmap_writeable(map, i) ? 'y' : 'n',
 450                            regmap_volatile(map, i) ? 'y' : 'n',
 451                            regmap_precious(map, i) ? 'y' : 'n');
 452         }
 453
 454         return 0;
 455 }
 456
 457 DEFINE_SHOW_ATTRIBUTE(regmap_access);
 458
 459 static ssize_t regmap_cache_only_write_file(struct file *file,
 460                                             const char __user *user_buf,
 461                                             size_t count, loff_t *ppos)
 462 {
 463         struct regmap *map = container_of(file->private_data,
 464                                           struct regmap, cache_only);
 465         bool new_val, require_sync = false;
 466         int err;
 467
 468         err = kstrtobool_from_user(user_buf, count, &new_val);
 469         /* Ignore malforned data like debugfs_write_file_bool() */
 470         if (err)
 471                 return count;
 472
 473         err = debugfs_file_get(file->f_path.dentry);
 474         if (err)
 475                 return err;
 476
 477         map->lock(map->lock_arg);
 478
 479         if (new_val && !map->cache_only) {
 480                 dev_warn(map->dev, "debugfs cache_only=Y forced\n");
 481                 add_taint(TAINT_USER, LOCKDEP_STILL_OK);
 482         } else if (!new_val && map->cache_only) {
 483                 dev_warn(map->dev, "debugfs cache_only=N forced: syncing cache\n");
 484                 require_sync = true;
 485         }
 486         map->cache_only = new_val;
 487
 488         map->unlock(map->lock_arg);
 489         debugfs_file_put(file->f_path.dentry);
 490
 491         if (require_sync) {
 492                 err = regcache_sync(map);
 493                 if (err)
 494                         dev_err(map->dev, "Failed to sync cache %d\n", err);
 495         }
 496
 497         return count;
 498 }
 499
 500 static const struct file_operations regmap_cache_only_fops = {
 501         .open = simple_open,
 502         .read = debugfs_read_file_bool,
 503         .write = regmap_cache_only_write_file,
 504 };
 505
 506 static ssize_t regmap_cache_bypass_write_file(struct file *file,
 507                                               const char __user *user_buf,
 508                                               size_t count, loff_t *ppos)
 509 {
 510         struct regmap *map = container_of(file->private_data,
 511                                           struct regmap, cache_bypass);
 512         bool new_val;
 513         int err;
 514
 515         err = kstrtobool_from_user(user_buf, count, &new_val);
 516         /* Ignore malforned data like debugfs_write_file_bool() */
 517         if (err)
 518                 return count;
 519
 520         err = debugfs_file_get(file->f_path.dentry);
 521         if (err)
 522                 return err;
 523
 524         map->lock(map->lock_arg);
 525
 526         if (new_val && !map->cache_bypass) {
 527                 dev_warn(map->dev, "debugfs cache_bypass=Y forced\n");
 528                 add_taint(TAINT_USER, LOCKDEP_STILL_OK);
 529         } else if (!new_val && map->cache_bypass) {
 530                 dev_warn(map->dev, "debugfs cache_bypass=N forced\n");
 531         }
 532         map->cache_bypass = new_val;
 533
 534         map->unlock(map->lock_arg);
 535         debugfs_file_put(file->f_path.dentry);
 536
 537         return count;
 538 }
 539
 540 static const struct file_operations regmap_cache_bypass_fops = {
 541         .open = simple_open,
 542         .read = debugfs_read_file_bool,
 543         .write = regmap_cache_bypass_write_file,
 544 };
 545
 546 void regmap_debugfs_init(struct regmap *map)
 547 {
 548         struct rb_node *next;
 549         struct regmap_range_node *range_node;
 550         const char *devname = "dummy";
 551         const char *name = map->name;
 552
 553         /*
 554          * Userspace can initiate reads from the hardware over debugfs.
 555          * Normally internal regmap structures and buffers are protected with
 556          * a mutex or a spinlock, but if the regmap owner decided to disable
 557          * all locking mechanisms, this is no longer the case. For safety:
 558          * don't create the debugfs entries if locking is disabled.
 559          */
 560         if (map->debugfs_disable) {
 561                 dev_dbg(map->dev, "regmap locking disabled - not creating debugfs entries\n");
 562                 return;
 563         }
 564
 565         /* If we don't have the debugfs root yet, postpone init */
 566         if (!regmap_debugfs_root) {
 567                 struct regmap_debugfs_node *node;
 568                 node = kzalloc(sizeof(*node), GFP_KERNEL);
 569                 if (!node)
 570                         return;
 571                 node->map = map;
 572                 mutex_lock(&regmap_debugfs_early_lock);
 573                 list_add(&node->link, &regmap_debugfs_early_list);
 574                 mutex_unlock(&regmap_debugfs_early_lock);
 575                 return;
 576         }
 577
 578         INIT_LIST_HEAD(&map->debugfs_off_cache);
 579         mutex_init(&map->cache_lock);
 580
 581         if (map->dev)
 582                 devname = dev_name(map->dev);
 583
 584         if (name) {
 585                 if (!map->debugfs_name) {
 586                         map->debugfs_name = kasprintf(GFP_KERNEL, "%s-%s",
 587                                               devname, name);
 588                         if (!map->debugfs_name)
 589                                 return;
 590                 }
 591                 name = map->debugfs_name;
 592         } else {
 593                 name = devname;
 594         }
 595
 596         if (!strcmp(name, "dummy")) {
 597                 kfree(map->debugfs_name);
 598                 map->debugfs_name = kasprintf(GFP_KERNEL, "dummy%d",
 599                                                 dummy_index);
 600                 if (!map->debugfs_name)
 601                         return;
 602                 name = map->debugfs_name;
 603                 dummy_index++;
 604         }
 605
 606         map->debugfs = debugfs_create_dir(name, regmap_debugfs_root);
 607
 608         debugfs_create_file("name", 0400, map->debugfs,
 609                             map, &regmap_name_fops);
 610
 611         debugfs_create_file("range", 0400, map->debugfs,
 612                             map, &regmap_reg_ranges_fops);
 613
 614         if (map->max_register || regmap_readable(map, 0)) {
 615                 umode_t registers_mode;
 616
 617 #if defined(REGMAP_ALLOW_WRITE_DEBUGFS)
 618                 registers_mode = 0600;
 619 #else
 620                 registers_mode = 0400;
 621 #endif
 622
 623                 debugfs_create_file("registers", registers_mode, map->debugfs,
 624                                     map, &regmap_map_fops);
 625                 debugfs_create_file("access", 0400, map->debugfs,
 626                                     map, &regmap_access_fops);
 627         }
 628
 629         if (map->cache_type) {
 630                 debugfs_create_file("cache_only", 0600, map->debugfs,
 631                                     &map->cache_only, &regmap_cache_only_fops);
 632                 debugfs_create_bool("cache_dirty", 0400, map->debugfs,
 633                                     &map->cache_dirty);
 634                 debugfs_create_file("cache_bypass", 0600, map->debugfs,
 635                                     &map->cache_bypass,
 636                                     &regmap_cache_bypass_fops);
 637         }
 638
 639         next = rb_first(&map->range_tree);
 640         while (next) {
 641                 range_node = rb_entry(next, struct regmap_range_node, node);
 642
 643                 if (range_node->name)
 644                         debugfs_create_file(range_node->name, 0400,
 645                                             map->debugfs, range_node,
 646                                             &regmap_range_fops);
 647
 648                 next = rb_next(&range_node->node);
 649         }
 650
 651         if (map->cache_ops && map->cache_ops->debugfs_init)
 652                 map->cache_ops->debugfs_init(map);
 653 }
 654
 655 void regmap_debugfs_exit(struct regmap *map)
 656 {
 657         if (map->debugfs) {
 658                 debugfs_remove_recursive(map->debugfs);
 659                 mutex_lock(&map->cache_lock);
 660                 regmap_debugfs_free_dump_cache(map);
 661                 mutex_unlock(&map->cache_lock);
 662                 kfree(map->debugfs_name);
 663                 map->debugfs_name = NULL;
 664         } else {
 665                 struct regmap_debugfs_node *node, *tmp;
 666
 667                 mutex_lock(&regmap_debugfs_early_lock);
 668                 list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list,
 669                                          link) {
 670                         if (node->map == map) {
 671                                 list_del(&node->link);
 672                                 kfree(node);
 673                         }
 674                 }
 675                 mutex_unlock(&regmap_debugfs_early_lock);
 676         }
 677 }
 678
 679 void regmap_debugfs_initcall(void)
 680 {
 681         struct regmap_debugfs_node *node, *tmp;
 682
 683         regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
 684
 685         mutex_lock(&regmap_debugfs_early_lock);
 686         list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list, link) {
 687                 regmap_debugfs_init(node->map);
 688                 list_del(&node->link);
 689                 kfree(node);
 690         }
 691         mutex_unlock(&regmap_debugfs_early_lock);
 692 }