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
18struct regmap_debugfs_node {
19 struct regmap *map;
20 struct list_head link;
21};
22
23static unsigned int dummy_index;
24static struct dentry *regmap_debugfs_root;
25static LIST_HEAD(regmap_debugfs_early_list);
26static DEFINE_MUTEX(regmap_debugfs_early_lock);
27
28/* Calculate the length of a fixed format */
29static size_t regmap_calc_reg_len(int max_val)
30{
31 return snprintf(NULL, size: 0, fmt: "%x", max_val);
32}
33
34static 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, fmt: "%s\n", name);
51 if (ret >= PAGE_SIZE) {
52 kfree(objp: buf);
53 return ret;
54 }
55
56 ret = simple_read_from_buffer(to: user_buf, count, ppos, from: buf, available: ret);
57 kfree(objp: buf);
58 return ret;
59}
60
61static const struct file_operations regmap_name_fops = {
62 .open = simple_open,
63 .read = regmap_name_read_file,
64 .llseek = default_llseek,
65};
66
67static void regmap_debugfs_free_dump_cache(struct regmap *map)
68{
69 struct regmap_debugfs_off_cache *c;
70
71 while (!list_empty(head: &map->debugfs_off_cache)) {
72 c = list_first_entry(&map->debugfs_off_cache,
73 struct regmap_debugfs_off_cache,
74 list);
75 list_del(entry: &c->list);
76 kfree(objp: c);
77 }
78}
79
80static 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 */
95static 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(lock: &map->cache_lock);
115 i = base;
116 if (list_empty(head: &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, reg: i)) {
120 if (c) {
121 c->max = p - 1;
122 c->max_reg = i - map->reg_stride;
123 list_add_tail(new: &c->list,
124 head: &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(lock: &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(new: &c->list,
152 head: &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(lock: &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(lock: &map->cache_lock);
177
178 return ret;
179}
180
181static 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(max_val: 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
193static 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: reg + map->reg_stride)) {
199 ret = reg + map->reg_stride;
200 } else {
201 mutex_lock(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(lock: &map->cache_lock);
211 }
212 return ret;
213}
214
215static 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_PAGE_ORDER))
230 count = PAGE_SIZE << MAX_PAGE_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, base: from, from: *ppos, pos: &p);
240
241 for (i = start_reg; i >= 0 && i <= to;
242 i = regmap_next_readable_reg(map, reg: 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 + buf_pos, size: count - buf_pos, fmt: "%.*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, reg: i, val: &val);
257 if (ret == 0)
258 snprintf(buf: buf + buf_pos, size: count - buf_pos,
259 fmt: "%.*x", map->debugfs_val_len, val);
260 else
261 memset(s: buf + buf_pos, c: 'X',
262 n: 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(to: user_buf, from: buf, n: buf_pos)) {
273 ret = -EFAULT;
274 goto out;
275 }
276
277 *ppos += buf_pos;
278
279out:
280 kfree(objp: buf);
281 return ret;
282}
283
284static 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, from: 0, to: 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 */
301static 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
337static 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
344static 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, from: range->range_min, to: range->range_max,
351 user_buf, count, ppos);
352}
353
354static const struct file_operations regmap_range_fops = {
355 .open = simple_open,
356 .read = regmap_range_read_file,
357 .llseek = default_llseek,
358};
359
360static 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_PAGE_ORDER))
377 count = PAGE_SIZE << MAX_PAGE_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(objp: 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, base: 0, from: *ppos, pos: &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(lock: &map->cache_lock);
401 list_for_each_entry(c, &map->debugfs_off_cache, list) {
402 entry_len = snprintf(buf: entry, PAGE_SIZE, fmt: "%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(to: buf + buf_pos, from: entry, len: entry_len);
408 buf_pos += entry_len;
409 }
410 p += entry_len;
411 }
412 mutex_unlock(lock: &map->cache_lock);
413
414 kfree(objp: entry);
415 ret = buf_pos;
416
417 if (copy_to_user(to: user_buf, from: buf, n: buf_pos)) {
418 ret = -EFAULT;
419 goto out_buf;
420 }
421
422 *ppos += buf_pos;
423out_buf:
424 kfree(objp: buf);
425 return ret;
426}
427
428static 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
434static 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(max_val: 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, reg: i) && !regmap_writeable(map, reg: i))
444 continue;
445
446 /* Format the register */
447 seq_printf(m: s, fmt: "%.*x: %c %c %c %c\n", reg_len, i,
448 regmap_readable(map, reg: i) ? 'y' : 'n',
449 regmap_writeable(map, reg: i) ? 'y' : 'n',
450 regmap_volatile(map, reg: i) ? 'y' : 'n',
451 regmap_precious(map, reg: i) ? 'y' : 'n');
452 }
453
454 return 0;
455}
456
457DEFINE_SHOW_ATTRIBUTE(regmap_access);
458
459static 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(s: user_buf, count, res: &new_val);
469 /* Ignore malforned data like debugfs_write_file_bool() */
470 if (err)
471 return count;
472
473 map->lock(map->lock_arg);
474
475 if (new_val && !map->cache_only) {
476 dev_warn(map->dev, "debugfs cache_only=Y forced\n");
477 add_taint(TAINT_USER, LOCKDEP_STILL_OK);
478 } else if (!new_val && map->cache_only) {
479 dev_warn(map->dev, "debugfs cache_only=N forced: syncing cache\n");
480 require_sync = true;
481 }
482 map->cache_only = new_val;
483
484 map->unlock(map->lock_arg);
485
486 if (require_sync) {
487 err = regcache_sync(map);
488 if (err)
489 dev_err(map->dev, "Failed to sync cache %d\n", err);
490 }
491
492 return count;
493}
494
495static const struct file_operations regmap_cache_only_fops = {
496 .open = simple_open,
497 .read = debugfs_read_file_bool,
498 .write = regmap_cache_only_write_file,
499};
500
501static ssize_t regmap_cache_bypass_write_file(struct file *file,
502 const char __user *user_buf,
503 size_t count, loff_t *ppos)
504{
505 struct regmap *map = container_of(file->private_data,
506 struct regmap, cache_bypass);
507 bool new_val;
508 int err;
509
510 err = kstrtobool_from_user(s: user_buf, count, res: &new_val);
511 /* Ignore malforned data like debugfs_write_file_bool() */
512 if (err)
513 return count;
514
515 map->lock(map->lock_arg);
516
517 if (new_val && !map->cache_bypass) {
518 dev_warn(map->dev, "debugfs cache_bypass=Y forced\n");
519 add_taint(TAINT_USER, LOCKDEP_STILL_OK);
520 } else if (!new_val && map->cache_bypass) {
521 dev_warn(map->dev, "debugfs cache_bypass=N forced\n");
522 }
523 map->cache_bypass = new_val;
524
525 map->unlock(map->lock_arg);
526
527 return count;
528}
529
530static const struct file_operations regmap_cache_bypass_fops = {
531 .open = simple_open,
532 .read = debugfs_read_file_bool,
533 .write = regmap_cache_bypass_write_file,
534};
535
536void regmap_debugfs_init(struct regmap *map)
537{
538 struct rb_node *next;
539 struct regmap_range_node *range_node;
540 const char *devname = "dummy";
541 const char *name = map->name;
542
543 /*
544 * Userspace can initiate reads from the hardware over debugfs.
545 * Normally internal regmap structures and buffers are protected with
546 * a mutex or a spinlock, but if the regmap owner decided to disable
547 * all locking mechanisms, this is no longer the case. For safety:
548 * don't create the debugfs entries if locking is disabled.
549 */
550 if (map->debugfs_disable) {
551 dev_dbg(map->dev, "regmap locking disabled - not creating debugfs entries\n");
552 return;
553 }
554
555 /* If we don't have the debugfs root yet, postpone init */
556 if (!regmap_debugfs_root) {
557 struct regmap_debugfs_node *node;
558 node = kzalloc(sizeof(*node), GFP_KERNEL);
559 if (!node)
560 return;
561 node->map = map;
562 mutex_lock(lock: &regmap_debugfs_early_lock);
563 list_add(new: &node->link, head: &regmap_debugfs_early_list);
564 mutex_unlock(lock: &regmap_debugfs_early_lock);
565 return;
566 }
567
568 INIT_LIST_HEAD(list: &map->debugfs_off_cache);
569 mutex_init(&map->cache_lock);
570
571 if (map->dev)
572 devname = dev_name(dev: map->dev);
573
574 if (name) {
575 if (!map->debugfs_name) {
576 map->debugfs_name = kasprintf(GFP_KERNEL, fmt: "%s-%s",
577 devname, name);
578 if (!map->debugfs_name)
579 return;
580 }
581 name = map->debugfs_name;
582 } else {
583 name = devname;
584 }
585
586 if (!strcmp(name, "dummy")) {
587 kfree(objp: map->debugfs_name);
588 map->debugfs_name = kasprintf(GFP_KERNEL, fmt: "dummy%d",
589 dummy_index);
590 if (!map->debugfs_name)
591 return;
592 name = map->debugfs_name;
593 dummy_index++;
594 }
595
596 map->debugfs = debugfs_create_dir(name, parent: regmap_debugfs_root);
597
598 debugfs_create_file("name", 0400, map->debugfs,
599 map, &regmap_name_fops);
600
601 debugfs_create_file("range", 0400, map->debugfs,
602 map, &regmap_reg_ranges_fops);
603
604 if (map->max_register || regmap_readable(map, reg: 0)) {
605 umode_t registers_mode;
606
607#if defined(REGMAP_ALLOW_WRITE_DEBUGFS)
608 registers_mode = 0600;
609#else
610 registers_mode = 0400;
611#endif
612
613 debugfs_create_file("registers", registers_mode, map->debugfs,
614 map, &regmap_map_fops);
615 debugfs_create_file("access", 0400, map->debugfs,
616 map, &regmap_access_fops);
617 }
618
619 if (map->cache_type) {
620 debugfs_create_file("cache_only", 0600, map->debugfs,
621 &map->cache_only, &regmap_cache_only_fops);
622 debugfs_create_bool(name: "cache_dirty", mode: 0400, parent: map->debugfs,
623 value: &map->cache_dirty);
624 debugfs_create_file("cache_bypass", 0600, map->debugfs,
625 &map->cache_bypass,
626 &regmap_cache_bypass_fops);
627 }
628
629 /*
630 * This could interfere with driver operation. Therefore, don't provide
631 * any real compile time configuration option for this feature. One will
632 * have to modify the source code directly in order to use it.
633 */
634#undef REGMAP_ALLOW_FORCE_WRITE_FIELD_DEBUGFS
635#ifdef REGMAP_ALLOW_FORCE_WRITE_FIELD_DEBUGFS
636 debugfs_create_bool("force_write_field", 0600, map->debugfs,
637 &map->force_write_field);
638#endif
639
640 next = rb_first(&map->range_tree);
641 while (next) {
642 range_node = rb_entry(next, struct regmap_range_node, node);
643
644 if (range_node->name)
645 debugfs_create_file(range_node->name, 0400,
646 map->debugfs, range_node,
647 &regmap_range_fops);
648
649 next = rb_next(&range_node->node);
650 }
651
652 if (map->cache_ops && map->cache_ops->debugfs_init)
653 map->cache_ops->debugfs_init(map);
654}
655
656void regmap_debugfs_exit(struct regmap *map)
657{
658 if (map->debugfs) {
659 debugfs_remove_recursive(dentry: map->debugfs);
660 mutex_lock(lock: &map->cache_lock);
661 regmap_debugfs_free_dump_cache(map);
662 mutex_unlock(lock: &map->cache_lock);
663 kfree(objp: map->debugfs_name);
664 map->debugfs_name = NULL;
665 } else {
666 struct regmap_debugfs_node *node, *tmp;
667
668 mutex_lock(lock: &regmap_debugfs_early_lock);
669 list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list,
670 link) {
671 if (node->map == map) {
672 list_del(entry: &node->link);
673 kfree(objp: node);
674 }
675 }
676 mutex_unlock(lock: &regmap_debugfs_early_lock);
677 }
678}
679
680void regmap_debugfs_initcall(void)
681{
682 struct regmap_debugfs_node *node, *tmp;
683
684 regmap_debugfs_root = debugfs_create_dir(name: "regmap", NULL);
685
686 mutex_lock(lock: &regmap_debugfs_early_lock);
687 list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list, link) {
688 regmap_debugfs_init(map: node->map);
689 list_del(entry: &node->link);
690 kfree(objp: node);
691 }
692 mutex_unlock(lock: &regmap_debugfs_early_lock);
693}
694