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, 0, "%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, "%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
 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(&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
 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(&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
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(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 + 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
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_ORDER - 1)))
230		count = PAGE_SIZE << (MAX_ORDER - 1);
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
279out:
280	kfree(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, 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 */
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, range->range_min, 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_ORDER - 1)))
377		count = PAGE_SIZE << (MAX_ORDER - 1);
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;
423out_buf:
424	kfree(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(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
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(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
500static 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
506static 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
540static 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
546void 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
655void 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
679void 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}