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