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 <broonie@opensource.wolfsonmicro.com>
   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         const char *name;
  21         struct list_head link;
  22 };
  23
  24 static unsigned int dummy_index;
  25 static struct dentry *regmap_debugfs_root;
  26 static LIST_HEAD(regmap_debugfs_early_list);
  27 static DEFINE_MUTEX(regmap_debugfs_early_lock);
  28
  29 /* Calculate the length of a fixed format  */
  30 static size_t regmap_calc_reg_len(int max_val)
  31 {
  32         return snprintf(NULL, 0, "%x", max_val);
  33 }
  34
  35 static ssize_t regmap_name_read_file(struct file *file,
  36                                      char __user *user_buf, size_t count,
  37                                      loff_t *ppos)
  38 {
  39         struct regmap *map = file->private_data;
  40         const char *name = "nodev";
  41         int ret;
  42         char *buf;
  43
  44         buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
  45         if (!buf)
  46                 return -ENOMEM;
  47
  48         if (map->dev && map->dev->driver)
  49                 name = map->dev->driver->name;
  50
  51         ret = snprintf(buf, PAGE_SIZE, "%s\n", name);
  52         if (ret < 0) {
  53                 kfree(buf);
  54                 return ret;
  55         }
  56
  57         ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
  58         kfree(buf);
  59         return ret;
  60 }
  61
  62 static const struct file_operations regmap_name_fops = {
  63         .open = simple_open,
  64         .read = regmap_name_read_file,
  65         .llseek = default_llseek,
  66 };
  67
  68 static void regmap_debugfs_free_dump_cache(struct regmap *map)
  69 {
  70         struct regmap_debugfs_off_cache *c;
  71
  72         while (!list_empty(&map->debugfs_off_cache)) {
  73                 c = list_first_entry(&map->debugfs_off_cache,
  74                                      struct regmap_debugfs_off_cache,
  75                                      list);
  76                 list_del(&c->list);
  77                 kfree(c);
  78         }
  79 }
  80
  81 static bool regmap_printable(struct regmap *map, unsigned int reg)
  82 {
  83         if (regmap_precious(map, reg))
  84                 return false;
  85
  86         if (!regmap_readable(map, reg) && !regmap_cached(map, reg))
  87                 return false;
  88
  89         return true;
  90 }
  91
  92 /*
  93  * Work out where the start offset maps into register numbers, bearing
  94  * in mind that we suppress hidden registers.
  95  */
  96 static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
  97                                                   unsigned int base,
  98                                                   loff_t from,
  99                                                   loff_t *pos)
 100 {
 101         struct regmap_debugfs_off_cache *c = NULL;
 102         loff_t p = 0;
 103         unsigned int i, ret;
 104         unsigned int fpos_offset;
 105         unsigned int reg_offset;
 106
 107         /* Suppress the cache if we're using a subrange */
 108         if (base)
 109                 return base;
 110
 111         /*
 112          * If we don't have a cache build one so we don't have to do a
 113          * linear scan each time.
 114          */
 115         mutex_lock(&map->cache_lock);
 116         i = base;
 117         if (list_empty(&map->debugfs_off_cache)) {
 118                 for (; i <= map->max_register; i += map->reg_stride) {
 119                         /* Skip unprinted registers, closing off cache entry */
 120                         if (!regmap_printable(map, i)) {
 121                                 if (c) {
 122                                         c->max = p - 1;
 123                                         c->max_reg = i - map->reg_stride;
 124                                         list_add_tail(&c->list,
 125                                                       &map->debugfs_off_cache);
 126                                         c = NULL;
 127                                 }
 128
 129                                 continue;
 130                         }
 131
 132                         /* No cache entry?  Start a new one */
 133                         if (!c) {
 134                                 c = kzalloc(sizeof(*c), GFP_KERNEL);
 135                                 if (!c) {
 136                                         regmap_debugfs_free_dump_cache(map);
 137                                         mutex_unlock(&map->cache_lock);
 138                                         return base;
 139                                 }
 140                                 c->min = p;
 141                                 c->base_reg = i;
 142                         }
 143
 144                         p += map->debugfs_tot_len;
 145                 }
 146         }
 147
 148         /* Close the last entry off if we didn't scan beyond it */
 149         if (c) {
 150                 c->max = p - 1;
 151                 c->max_reg = i - map->reg_stride;
 152                 list_add_tail(&c->list,
 153                               &map->debugfs_off_cache);
 154         }
 155
 156         /*
 157          * This should never happen; we return above if we fail to
 158          * allocate and we should never be in this code if there are
 159          * no registers at all.
 160          */
 161         WARN_ON(list_empty(&map->debugfs_off_cache));
 162         ret = base;
 163
 164         /* Find the relevant block:offset */
 165         list_for_each_entry(c, &map->debugfs_off_cache, list) {
 166                 if (from >= c->min && from <= c->max) {
 167                         fpos_offset = from - c->min;
 168                         reg_offset = fpos_offset / map->debugfs_tot_len;
 169                         *pos = c->min + (reg_offset * map->debugfs_tot_len);
 170                         mutex_unlock(&map->cache_lock);
 171                         return c->base_reg + (reg_offset * map->reg_stride);
 172                 }
 173
 174                 *pos = c->max;
 175                 ret = c->max_reg;
 176         }
 177         mutex_unlock(&map->cache_lock);
 178
 179         return ret;
 180 }
 181
 182 static inline void regmap_calc_tot_len(struct regmap *map,
 183                                        void *buf, size_t count)
 184 {
 185         /* Calculate the length of a fixed format  */
 186         if (!map->debugfs_tot_len) {
 187                 map->debugfs_reg_len = regmap_calc_reg_len(map->max_register),
 188                 map->debugfs_val_len = 2 * map->format.val_bytes;
 189                 map->debugfs_tot_len = map->debugfs_reg_len +
 190                         map->debugfs_val_len + 3;      /* : \n */
 191         }
 192 }
 193
 194 static int regmap_next_readable_reg(struct regmap *map, int reg)
 195 {
 196         struct regmap_debugfs_off_cache *c;
 197         int ret = -EINVAL;
 198
 199         if (regmap_printable(map, reg + map->reg_stride)) {
 200                 ret = reg + map->reg_stride;
 201         } else {
 202                 mutex_lock(&map->cache_lock);
 203                 list_for_each_entry(c, &map->debugfs_off_cache, list) {
 204                         if (reg > c->max_reg)
 205                                 continue;
 206                         if (reg < c->base_reg) {
 207                                 ret = c->base_reg;
 208                                 break;
 209                         }
 210                 }
 211                 mutex_unlock(&map->cache_lock);
 212         }
 213         return ret;
 214 }
 215
 216 static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
 217                                    unsigned int to, char __user *user_buf,
 218                                    size_t count, loff_t *ppos)
 219 {
 220         size_t buf_pos = 0;
 221         loff_t p = *ppos;
 222         ssize_t ret;
 223         int i;
 224         char *buf;
 225         unsigned int val, start_reg;
 226
 227         if (*ppos < 0 || !count)
 228                 return -EINVAL;
 229
 230         if (count > (PAGE_SIZE << (MAX_ORDER - 1)))
 231                 count = PAGE_SIZE << (MAX_ORDER - 1);
 232
 233         buf = kmalloc(count, GFP_KERNEL);
 234         if (!buf)
 235                 return -ENOMEM;
 236
 237         regmap_calc_tot_len(map, buf, count);
 238
 239         /* Work out which register we're starting at */
 240         start_reg = regmap_debugfs_get_dump_start(map, from, *ppos, &p);
 241
 242         for (i = start_reg; i >= 0 && i <= to;
 243              i = regmap_next_readable_reg(map, i)) {
 244
 245                 /* If we're in the region the user is trying to read */
 246                 if (p >= *ppos) {
 247                         /* ...but not beyond it */
 248                         if (buf_pos + map->debugfs_tot_len > count)
 249                                 break;
 250
 251                         /* Format the register */
 252                         snprintf(buf + buf_pos, count - buf_pos, "%.*x: ",
 253                                  map->debugfs_reg_len, i - from);
 254                         buf_pos += map->debugfs_reg_len + 2;
 255
 256                         /* Format the value, write all X if we can't read */
 257                         ret = regmap_read(map, i, &val);
 258                         if (ret == 0)
 259                                 snprintf(buf + buf_pos, count - buf_pos,
 260                                          "%.*x", map->debugfs_val_len, val);
 261                         else
 262                                 memset(buf + buf_pos, 'X',
 263                                        map->debugfs_val_len);
 264                         buf_pos += 2 * map->format.val_bytes;
 265
 266                         buf[buf_pos++] = '\n';
 267                 }
 268                 p += map->debugfs_tot_len;
 269         }
 270
 271         ret = buf_pos;
 272
 273         if (copy_to_user(user_buf, buf, buf_pos)) {
 274                 ret = -EFAULT;
 275                 goto out;
 276         }
 277
 278         *ppos += buf_pos;
 279
 280 out:
 281         kfree(buf);
 282         return ret;
 283 }
 284
 285 static ssize_t regmap_map_read_file(struct file *file, char __user *user_buf,
 286                                     size_t count, loff_t *ppos)
 287 {
 288         struct regmap *map = file->private_data;
 289
 290         return regmap_read_debugfs(map, 0, map->max_register, user_buf,
 291                                    count, ppos);
 292 }
 293
 294 #undef REGMAP_ALLOW_WRITE_DEBUGFS
 295 #ifdef REGMAP_ALLOW_WRITE_DEBUGFS
 296 /*
 297  * This can be dangerous especially when we have clients such as
 298  * PMICs, therefore don't provide any real compile time configuration option
 299  * for this feature, people who want to use this will need to modify
 300  * the source code directly.
 301  */
 302 static ssize_t regmap_map_write_file(struct file *file,
 303                                      const char __user *user_buf,
 304                                      size_t count, loff_t *ppos)
 305 {
 306         char buf[32];
 307         size_t buf_size;
 308         char *start = buf;
 309         unsigned long reg, value;
 310         struct regmap *map = file->private_data;
 311         int ret;
 312
 313         buf_size = min(count, (sizeof(buf)-1));
 314         if (copy_from_user(buf, user_buf, buf_size))
 315                 return -EFAULT;
 316         buf[buf_size] = 0;
 317
 318         while (*start == ' ')
 319                 start++;
 320         reg = simple_strtoul(start, &start, 16);
 321         while (*start == ' ')
 322                 start++;
 323         if (kstrtoul(start, 16, &value))
 324                 return -EINVAL;
 325
 326         /* Userspace has been fiddling around behind the kernel's back */
 327         add_taint(TAINT_USER, LOCKDEP_STILL_OK);
 328
 329         ret = regmap_write(map, reg, value);
 330         if (ret < 0)
 331                 return ret;
 332         return buf_size;
 333 }
 334 #else
 335 #define regmap_map_write_file NULL
 336 #endif
 337
 338 static const struct file_operations regmap_map_fops = {
 339         .open = simple_open,
 340         .read = regmap_map_read_file,
 341         .write = regmap_map_write_file,
 342         .llseek = default_llseek,
 343 };
 344
 345 static ssize_t regmap_range_read_file(struct file *file, char __user *user_buf,
 346                                       size_t count, loff_t *ppos)
 347 {
 348         struct regmap_range_node *range = file->private_data;
 349         struct regmap *map = range->map;
 350
 351         return regmap_read_debugfs(map, range->range_min, range->range_max,
 352                                    user_buf, count, ppos);
 353 }
 354
 355 static const struct file_operations regmap_range_fops = {
 356         .open = simple_open,
 357         .read = regmap_range_read_file,
 358         .llseek = default_llseek,
 359 };
 360
 361 static ssize_t regmap_reg_ranges_read_file(struct file *file,
 362                                            char __user *user_buf, size_t count,
 363                                            loff_t *ppos)
 364 {
 365         struct regmap *map = file->private_data;
 366         struct regmap_debugfs_off_cache *c;
 367         loff_t p = 0;
 368         size_t buf_pos = 0;
 369         char *buf;
 370         char *entry;
 371         int ret;
 372         unsigned entry_len;
 373
 374         if (*ppos < 0 || !count)
 375                 return -EINVAL;
 376
 377         if (count > (PAGE_SIZE << (MAX_ORDER - 1)))
 378                 count = PAGE_SIZE << (MAX_ORDER - 1);
 379
 380         buf = kmalloc(count, GFP_KERNEL);
 381         if (!buf)
 382                 return -ENOMEM;
 383
 384         entry = kmalloc(PAGE_SIZE, GFP_KERNEL);
 385         if (!entry) {
 386                 kfree(buf);
 387                 return -ENOMEM;
 388         }
 389
 390         /* While we are at it, build the register dump cache
 391          * now so the read() operation on the `registers' file
 392          * can benefit from using the cache.  We do not care
 393          * about the file position information that is contained
 394          * in the cache, just about the actual register blocks */
 395         regmap_calc_tot_len(map, buf, count);
 396         regmap_debugfs_get_dump_start(map, 0, *ppos, &p);
 397
 398         /* Reset file pointer as the fixed-format of the `registers'
 399          * file is not compatible with the `range' file */
 400         p = 0;
 401         mutex_lock(&map->cache_lock);
 402         list_for_each_entry(c, &map->debugfs_off_cache, list) {
 403                 entry_len = snprintf(entry, PAGE_SIZE, "%x-%x\n",
 404                                      c->base_reg, c->max_reg);
 405                 if (p >= *ppos) {
 406                         if (buf_pos + entry_len > count)
 407                                 break;
 408                         memcpy(buf + buf_pos, entry, entry_len);
 409                         buf_pos += entry_len;
 410                 }
 411                 p += entry_len;
 412         }
 413         mutex_unlock(&map->cache_lock);
 414
 415         kfree(entry);
 416         ret = buf_pos;
 417
 418         if (copy_to_user(user_buf, buf, buf_pos)) {
 419                 ret = -EFAULT;
 420                 goto out_buf;
 421         }
 422
 423         *ppos += buf_pos;
 424 out_buf:
 425         kfree(buf);
 426         return ret;
 427 }
 428
 429 static const struct file_operations regmap_reg_ranges_fops = {
 430         .open = simple_open,
 431         .read = regmap_reg_ranges_read_file,
 432         .llseek = default_llseek,
 433 };
 434
 435 static int regmap_access_show(struct seq_file *s, void *ignored)
 436 {
 437         struct regmap *map = s->private;
 438         int i, reg_len;
 439
 440         reg_len = regmap_calc_reg_len(map->max_register);
 441
 442         for (i = 0; i <= map->max_register; i += map->reg_stride) {
 443                 /* Ignore registers which are neither readable nor writable */
 444                 if (!regmap_readable(map, i) && !regmap_writeable(map, i))
 445                         continue;
 446
 447                 /* Format the register */
 448                 seq_printf(s, "%.*x: %c %c %c %c\n", reg_len, i,
 449                            regmap_readable(map, i) ? 'y' : 'n',
 450                            regmap_writeable(map, i) ? 'y' : 'n',
 451                            regmap_volatile(map, i) ? 'y' : 'n',
 452                            regmap_precious(map, i) ? 'y' : 'n');
 453         }
 454
 455         return 0;
 456 }
 457
 458 DEFINE_SHOW_ATTRIBUTE(regmap_access);
 459
 460 static ssize_t regmap_cache_only_write_file(struct file *file,
 461                                             const char __user *user_buf,
 462                                             size_t count, loff_t *ppos)
 463 {
 464         struct regmap *map = container_of(file->private_data,
 465                                           struct regmap, cache_only);
 466         bool new_val, require_sync = false;
 467         int err;
 468
 469         err = kstrtobool_from_user(user_buf, count, &new_val);
 470         /* Ignore malforned data like debugfs_write_file_bool() */
 471         if (err)
 472                 return count;
 473
 474         err = debugfs_file_get(file->f_path.dentry);
 475         if (err)
 476                 return err;
 477
 478         map->lock(map->lock_arg);
 479
 480         if (new_val && !map->cache_only) {
 481                 dev_warn(map->dev, "debugfs cache_only=Y forced\n");
 482                 add_taint(TAINT_USER, LOCKDEP_STILL_OK);
 483         } else if (!new_val && map->cache_only) {
 484                 dev_warn(map->dev, "debugfs cache_only=N forced: syncing cache\n");
 485                 require_sync = true;
 486         }
 487         map->cache_only = new_val;
 488
 489         map->unlock(map->lock_arg);
 490         debugfs_file_put(file->f_path.dentry);
 491
 492         if (require_sync) {
 493                 err = regcache_sync(map);
 494                 if (err)
 495                         dev_err(map->dev, "Failed to sync cache %d\n", err);
 496         }
 497
 498         return count;
 499 }
 500
 501 static const struct file_operations regmap_cache_only_fops = {
 502         .open = simple_open,
 503         .read = debugfs_read_file_bool,
 504         .write = regmap_cache_only_write_file,
 505 };
 506
 507 static ssize_t regmap_cache_bypass_write_file(struct file *file,
 508                                               const char __user *user_buf,
 509                                               size_t count, loff_t *ppos)
 510 {
 511         struct regmap *map = container_of(file->private_data,
 512                                           struct regmap, cache_bypass);
 513         bool new_val;
 514         int err;
 515
 516         err = kstrtobool_from_user(user_buf, count, &new_val);
 517         /* Ignore malforned data like debugfs_write_file_bool() */
 518         if (err)
 519                 return count;
 520
 521         err = debugfs_file_get(file->f_path.dentry);
 522         if (err)
 523                 return err;
 524
 525         map->lock(map->lock_arg);
 526
 527         if (new_val && !map->cache_bypass) {
 528                 dev_warn(map->dev, "debugfs cache_bypass=Y forced\n");
 529                 add_taint(TAINT_USER, LOCKDEP_STILL_OK);
 530         } else if (!new_val && map->cache_bypass) {
 531                 dev_warn(map->dev, "debugfs cache_bypass=N forced\n");
 532         }
 533         map->cache_bypass = new_val;
 534
 535         map->unlock(map->lock_arg);
 536         debugfs_file_put(file->f_path.dentry);
 537
 538         return count;
 539 }
 540
 541 static const struct file_operations regmap_cache_bypass_fops = {
 542         .open = simple_open,
 543         .read = debugfs_read_file_bool,
 544         .write = regmap_cache_bypass_write_file,
 545 };
 546
 547 void regmap_debugfs_init(struct regmap *map, const char *name)
 548 {
 549         struct rb_node *next;
 550         struct regmap_range_node *range_node;
 551         const char *devname = "dummy";
 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                 node->name = name;
 573                 mutex_lock(&regmap_debugfs_early_lock);
 574                 list_add(&node->link, &regmap_debugfs_early_list);
 575                 mutex_unlock(&regmap_debugfs_early_lock);
 576                 return;
 577         }
 578
 579         INIT_LIST_HEAD(&map->debugfs_off_cache);
 580         mutex_init(&map->cache_lock);
 581
 582         if (map->dev)
 583                 devname = dev_name(map->dev);
 584
 585         if (name) {
 586                 map->debugfs_name = kasprintf(GFP_KERNEL, "%s-%s",
 587                                               devname, name);
 588                 name = map->debugfs_name;
 589         } else {
 590                 name = devname;
 591         }
 592
 593         if (!strcmp(name, "dummy")) {
 594                 kfree(map->debugfs_name);
 595
 596                 map->debugfs_name = kasprintf(GFP_KERNEL, "dummy%d",
 597                                                 dummy_index);
 598                 name = map->debugfs_name;
 599                 dummy_index++;
 600         }
 601
 602         map->debugfs = debugfs_create_dir(name, regmap_debugfs_root);
 603
 604         debugfs_create_file("name", 0400, map->debugfs,
 605                             map, &regmap_name_fops);
 606
 607         debugfs_create_file("range", 0400, map->debugfs,
 608                             map, &regmap_reg_ranges_fops);
 609
 610         if (map->max_register || regmap_readable(map, 0)) {
 611                 umode_t registers_mode;
 612
 613 #if defined(REGMAP_ALLOW_WRITE_DEBUGFS)
 614                 registers_mode = 0600;
 615 #else
 616                 registers_mode = 0400;
 617 #endif
 618
 619                 debugfs_create_file("registers", registers_mode, map->debugfs,
 620                                     map, &regmap_map_fops);
 621                 debugfs_create_file("access", 0400, map->debugfs,
 622                                     map, &regmap_access_fops);
 623         }
 624
 625         if (map->cache_type) {
 626                 debugfs_create_file("cache_only", 0600, map->debugfs,
 627                                     &map->cache_only, &regmap_cache_only_fops);
 628                 debugfs_create_bool("cache_dirty", 0400, map->debugfs,
 629                                     &map->cache_dirty);
 630                 debugfs_create_file("cache_bypass", 0600, map->debugfs,
 631                                     &map->cache_bypass,
 632                                     &regmap_cache_bypass_fops);
 633         }
 634
 635         next = rb_first(&map->range_tree);
 636         while (next) {
 637                 range_node = rb_entry(next, struct regmap_range_node, node);
 638
 639                 if (range_node->name)
 640                         debugfs_create_file(range_node->name, 0400,
 641                                             map->debugfs, range_node,
 642                                             &regmap_range_fops);
 643
 644                 next = rb_next(&range_node->node);
 645         }
 646
 647         if (map->cache_ops && map->cache_ops->debugfs_init)
 648                 map->cache_ops->debugfs_init(map);
 649 }
 650
 651 void regmap_debugfs_exit(struct regmap *map)
 652 {
 653         if (map->debugfs) {
 654                 debugfs_remove_recursive(map->debugfs);
 655                 mutex_lock(&map->cache_lock);
 656                 regmap_debugfs_free_dump_cache(map);
 657                 mutex_unlock(&map->cache_lock);
 658                 kfree(map->debugfs_name);
 659         } else {
 660                 struct regmap_debugfs_node *node, *tmp;
 661
 662                 mutex_lock(&regmap_debugfs_early_lock);
 663                 list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list,
 664                                          link) {
 665                         if (node->map == map) {
 666                                 list_del(&node->link);
 667                                 kfree(node);
 668                         }
 669                 }
 670                 mutex_unlock(&regmap_debugfs_early_lock);
 671         }
 672 }
 673
 674 void regmap_debugfs_initcall(void)
 675 {
 676         struct regmap_debugfs_node *node, *tmp;
 677
 678         regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
 679
 680         mutex_lock(&regmap_debugfs_early_lock);
 681         list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list, link) {
 682                 regmap_debugfs_init(node->map, node->name);
 683                 list_del(&node->link);
 684                 kfree(node);
 685         }
 686         mutex_unlock(&regmap_debugfs_early_lock);
 687 }