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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#include <linux/idr.h>
16
17#include "internal.h"
18
19struct regmap_debugfs_node {
20 struct regmap *map;
21 struct list_head link;
22};
23
24static DEFINE_IDA(dummy_ida);
25static struct dentry *regmap_debugfs_root;
26static LIST_HEAD(regmap_debugfs_early_list);
27static DEFINE_MUTEX(regmap_debugfs_early_lock);
28
29/* Calculate the length of a fixed format */
30static size_t regmap_calc_reg_len(int max_val)
31{
32 return snprintf(NULL, 0, "%x", max_val);
33}
34
35static 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 >= PAGE_SIZE) {
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
62static const struct file_operations regmap_name_fops = {
63 .open = simple_open,
64 .read = regmap_name_read_file,
65 .llseek = default_llseek,
66};
67
68static 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
81static 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 */
96static 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_obj(*c);
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
182static 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
194static 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
216static 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_PAGE_ORDER))
231 count = PAGE_SIZE << MAX_PAGE_ORDER;
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
280out:
281 kfree(buf);
282 return ret;
283}
284
285static 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 */
302static 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
338static 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
345static 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
355static const struct file_operations regmap_range_fops = {
356 .open = simple_open,
357 .read = regmap_range_read_file,
358 .llseek = default_llseek,
359};
360
361static 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 int entry_len;
373
374 if (*ppos < 0 || !count)
375 return -EINVAL;
376
377 if (count > (PAGE_SIZE << MAX_PAGE_ORDER))
378 count = PAGE_SIZE << MAX_PAGE_ORDER;
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;
424out_buf:
425 kfree(buf);
426 return ret;
427}
428
429static 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
435static 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
458DEFINE_SHOW_ATTRIBUTE(regmap_access);
459
460static 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 map->lock(map->lock_arg);
475
476 if (new_val && !map->cache_only) {
477 dev_warn(map->dev, "debugfs cache_only=Y forced\n");
478 add_taint(TAINT_USER, LOCKDEP_STILL_OK);
479 } else if (!new_val && map->cache_only) {
480 dev_warn(map->dev, "debugfs cache_only=N forced: syncing cache\n");
481 require_sync = true;
482 }
483 map->cache_only = new_val;
484
485 map->unlock(map->lock_arg);
486
487 if (require_sync) {
488 err = regcache_sync(map);
489 if (err)
490 dev_err(map->dev, "Failed to sync cache %d\n", err);
491 }
492
493 return count;
494}
495
496static const struct file_operations regmap_cache_only_fops = {
497 .open = simple_open,
498 .read = debugfs_read_file_bool,
499 .write = regmap_cache_only_write_file,
500};
501
502static ssize_t regmap_cache_bypass_write_file(struct file *file,
503 const char __user *user_buf,
504 size_t count, loff_t *ppos)
505{
506 struct regmap *map = container_of(file->private_data,
507 struct regmap, cache_bypass);
508 bool new_val;
509 int err;
510
511 err = kstrtobool_from_user(user_buf, count, &new_val);
512 /* Ignore malforned data like debugfs_write_file_bool() */
513 if (err)
514 return count;
515
516 map->lock(map->lock_arg);
517
518 if (new_val && !map->cache_bypass) {
519 dev_warn(map->dev, "debugfs cache_bypass=Y forced\n");
520 add_taint(TAINT_USER, LOCKDEP_STILL_OK);
521 } else if (!new_val && map->cache_bypass) {
522 dev_warn(map->dev, "debugfs cache_bypass=N forced\n");
523 }
524 map->cache_bypass = new_val;
525
526 map->unlock(map->lock_arg);
527
528 return count;
529}
530
531static const struct file_operations regmap_cache_bypass_fops = {
532 .open = simple_open,
533 .read = debugfs_read_file_bool,
534 .write = regmap_cache_bypass_write_file,
535};
536
537void regmap_debugfs_init(struct regmap *map)
538{
539 struct rb_node *next;
540 struct regmap_range_node *range_node;
541 const char *devname = "dummy";
542 const char *name = map->name;
543 int id;
544
545 /*
546 * Userspace can initiate reads from the hardware over debugfs.
547 * Normally internal regmap structures and buffers are protected with
548 * a mutex or a spinlock, but if the regmap owner decided to disable
549 * all locking mechanisms, this is no longer the case. For safety:
550 * don't create the debugfs entries if locking is disabled.
551 */
552 if (map->debugfs_disable) {
553 dev_dbg(map->dev, "regmap locking disabled - not creating debugfs entries\n");
554 return;
555 }
556
557 /* If we don't have the debugfs root yet, postpone init */
558 if (!regmap_debugfs_root) {
559 struct regmap_debugfs_node *node;
560 node = kzalloc_obj(*node);
561 if (!node)
562 return;
563 node->map = map;
564 mutex_lock(&regmap_debugfs_early_lock);
565 list_add(&node->link, &regmap_debugfs_early_list);
566 mutex_unlock(&regmap_debugfs_early_lock);
567 return;
568 }
569
570 INIT_LIST_HEAD(&map->debugfs_off_cache);
571 mutex_init(&map->cache_lock);
572 map->debugfs_dummy_id = -1;
573
574 if (map->dev)
575 devname = dev_name(map->dev);
576
577 if (name) {
578 if (!map->debugfs_name) {
579 map->debugfs_name = kasprintf(GFP_KERNEL, "%s-%s",
580 devname, name);
581 if (!map->debugfs_name)
582 return;
583 }
584 name = map->debugfs_name;
585 } else {
586 name = devname;
587 }
588
589 if (!strcmp(name, "dummy")) {
590 kfree(map->debugfs_name);
591 id = ida_alloc(&dummy_ida, GFP_KERNEL);
592 if (id < 0)
593 return;
594 map->debugfs_name = kasprintf(GFP_KERNEL, "dummy%d", id);
595 if (!map->debugfs_name) {
596 ida_free(&dummy_ida, id);
597 return;
598 }
599 map->debugfs_dummy_id = id;
600 name = map->debugfs_name;
601 }
602
603 map->debugfs = debugfs_create_dir(name, regmap_debugfs_root);
604
605 debugfs_create_file("name", 0400, map->debugfs,
606 map, &regmap_name_fops);
607
608 debugfs_create_file("range", 0400, map->debugfs,
609 map, &regmap_reg_ranges_fops);
610
611 if (map->max_register || regmap_readable(map, 0)) {
612 umode_t registers_mode;
613
614#if defined(REGMAP_ALLOW_WRITE_DEBUGFS)
615 registers_mode = 0600;
616#else
617 registers_mode = 0400;
618#endif
619
620 debugfs_create_file("registers", registers_mode, map->debugfs,
621 map, &regmap_map_fops);
622 debugfs_create_file("access", 0400, map->debugfs,
623 map, &regmap_access_fops);
624 }
625
626 if (map->cache_type) {
627 debugfs_create_file("cache_only", 0600, map->debugfs,
628 &map->cache_only, &regmap_cache_only_fops);
629 debugfs_create_bool("cache_dirty", 0400, map->debugfs,
630 &map->cache_dirty);
631 debugfs_create_file("cache_bypass", 0600, map->debugfs,
632 &map->cache_bypass,
633 &regmap_cache_bypass_fops);
634 }
635
636 /*
637 * This could interfere with driver operation. Therefore, don't provide
638 * any real compile time configuration option for this feature. One will
639 * have to modify the source code directly in order to use it.
640 */
641#undef REGMAP_ALLOW_FORCE_WRITE_FIELD_DEBUGFS
642#ifdef REGMAP_ALLOW_FORCE_WRITE_FIELD_DEBUGFS
643 debugfs_create_bool("force_write_field", 0600, map->debugfs,
644 &map->force_write_field);
645#endif
646
647 next = rb_first(&map->range_tree);
648 while (next) {
649 range_node = rb_entry(next, struct regmap_range_node, node);
650
651 if (range_node->name)
652 debugfs_create_file(range_node->name, 0400,
653 map->debugfs, range_node,
654 &regmap_range_fops);
655
656 next = rb_next(&range_node->node);
657 }
658
659 if (map->cache_ops && map->cache_ops->debugfs_init)
660 map->cache_ops->debugfs_init(map);
661}
662
663void regmap_debugfs_exit(struct regmap *map)
664{
665 if (map->debugfs) {
666 debugfs_remove_recursive(map->debugfs);
667 map->debugfs = NULL;
668 mutex_lock(&map->cache_lock);
669 regmap_debugfs_free_dump_cache(map);
670 mutex_unlock(&map->cache_lock);
671 if (map->debugfs_dummy_id >= 0) {
672 ida_free(&dummy_ida, map->debugfs_dummy_id);
673 map->debugfs_dummy_id = -1;
674 }
675 kfree(map->debugfs_name);
676 map->debugfs_name = NULL;
677 } else {
678 struct regmap_debugfs_node *node, *tmp;
679
680 mutex_lock(&regmap_debugfs_early_lock);
681 list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list,
682 link) {
683 if (node->map == map) {
684 list_del(&node->link);
685 kfree(node);
686 }
687 }
688 mutex_unlock(&regmap_debugfs_early_lock);
689 }
690}
691
692void regmap_debugfs_initcall(void)
693{
694 struct regmap_debugfs_node *node, *tmp;
695
696 regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
697
698 mutex_lock(&regmap_debugfs_early_lock);
699 list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list, link) {
700 regmap_debugfs_init(node->map);
701 list_del(&node->link);
702 kfree(node);
703 }
704 mutex_unlock(&regmap_debugfs_early_lock);
705}