1/*
2 * Register map access API - debugfs
3 *
4 * Copyright 2011 Wolfson Microelectronics plc
5 *
6 * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13#include <linux/slab.h>
14#include <linux/mutex.h>
15#include <linux/debugfs.h>
16#include <linux/uaccess.h>
17#include <linux/device.h>
18#include <linux/list.h>
19
20#include "internal.h"
21
22struct regmap_debugfs_node {
23	struct regmap *map;
24	const char *name;
25	struct list_head link;
26};
27
28static struct dentry *regmap_debugfs_root;
29static LIST_HEAD(regmap_debugfs_early_list);
30static DEFINE_MUTEX(regmap_debugfs_early_lock);
31
32/* Calculate the length of a fixed format  */
33static size_t regmap_calc_reg_len(int max_val, char *buf, size_t buf_size)
34{
35	return snprintf(NULL, 0, "%x", max_val);
36}
37
38static ssize_t regmap_name_read_file(struct file *file,
39				     char __user *user_buf, size_t count,
40				     loff_t *ppos)
41{
42	struct regmap *map = file->private_data;
43	int ret;
44	char *buf;
45
46	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
47	if (!buf)
48		return -ENOMEM;
49
50	ret = snprintf(buf, PAGE_SIZE, "%s\n", map->dev->driver->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
80/*
81 * Work out where the start offset maps into register numbers, bearing
82 * in mind that we suppress hidden registers.
83 */
84static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
85						  unsigned int base,
86						  loff_t from,
87						  loff_t *pos)
88{
89	struct regmap_debugfs_off_cache *c = NULL;
90	loff_t p = 0;
91	unsigned int i, ret;
92	unsigned int fpos_offset;
93	unsigned int reg_offset;
94
95	/* Suppress the cache if we're using a subrange */
96	if (base)
97		return base;
98
99	/*
100	 * If we don't have a cache build one so we don't have to do a
101	 * linear scan each time.
102	 */
103	mutex_lock(&map->cache_lock);
104	i = base;
105	if (list_empty(&map->debugfs_off_cache)) {
106		for (; i <= map->max_register; i += map->reg_stride) {
107			/* Skip unprinted registers, closing off cache entry */
108			if (!regmap_readable(map, i) ||
109			    regmap_precious(map, i)) {
110				if (c) {
111					c->max = p - 1;
112					c->max_reg = i - map->reg_stride;
113					list_add_tail(&c->list,
114						      &map->debugfs_off_cache);
115					c = NULL;
116				}
117
118				continue;
119			}
120
121			/* No cache entry?  Start a new one */
122			if (!c) {
123				c = kzalloc(sizeof(*c), GFP_KERNEL);
124				if (!c) {
125					regmap_debugfs_free_dump_cache(map);
126					mutex_unlock(&map->cache_lock);
127					return base;
128				}
129				c->min = p;
130				c->base_reg = i;
131			}
132
133			p += map->debugfs_tot_len;
134		}
135	}
136
137	/* Close the last entry off if we didn't scan beyond it */
138	if (c) {
139		c->max = p - 1;
140		c->max_reg = i - map->reg_stride;
141		list_add_tail(&c->list,
142			      &map->debugfs_off_cache);
143	}
144
145	/*
146	 * This should never happen; we return above if we fail to
147	 * allocate and we should never be in this code if there are
148	 * no registers at all.
149	 */
150	WARN_ON(list_empty(&map->debugfs_off_cache));
151	ret = base;
152
153	/* Find the relevant block:offset */
154	list_for_each_entry(c, &map->debugfs_off_cache, list) {
155		if (from >= c->min && from <= c->max) {
156			fpos_offset = from - c->min;
157			reg_offset = fpos_offset / map->debugfs_tot_len;
158			*pos = c->min + (reg_offset * map->debugfs_tot_len);
159			mutex_unlock(&map->cache_lock);
160			return c->base_reg + (reg_offset * map->reg_stride);
161		}
162
163		*pos = c->max;
164		ret = c->max_reg;
165	}
166	mutex_unlock(&map->cache_lock);
167
168	return ret;
169}
170
171static inline void regmap_calc_tot_len(struct regmap *map,
172				       void *buf, size_t count)
173{
174	/* Calculate the length of a fixed format  */
175	if (!map->debugfs_tot_len) {
176		map->debugfs_reg_len = regmap_calc_reg_len(map->max_register,
177							   buf, count);
178		map->debugfs_val_len = 2 * map->format.val_bytes;
179		map->debugfs_tot_len = map->debugfs_reg_len +
180			map->debugfs_val_len + 3;      /* : \n */
181	}
182}
183
184static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
185				   unsigned int to, char __user *user_buf,
186				   size_t count, loff_t *ppos)
187{
188	size_t buf_pos = 0;
189	loff_t p = *ppos;
190	ssize_t ret;
191	int i;
192	char *buf;
193	unsigned int val, start_reg;
194
195	if (*ppos < 0 || !count)
196		return -EINVAL;
197
198	buf = kmalloc(count, GFP_KERNEL);
199	if (!buf)
200		return -ENOMEM;
201
202	regmap_calc_tot_len(map, buf, count);
203
204	/* Work out which register we're starting at */
205	start_reg = regmap_debugfs_get_dump_start(map, from, *ppos, &p);
206
207	for (i = start_reg; i <= to; i += map->reg_stride) {
208		if (!regmap_readable(map, i))
209			continue;
210
211		if (regmap_precious(map, i))
212			continue;
213
214		/* If we're in the region the user is trying to read */
215		if (p >= *ppos) {
216			/* ...but not beyond it */
217			if (buf_pos + map->debugfs_tot_len > count)
218				break;
219
220			/* Format the register */
221			snprintf(buf + buf_pos, count - buf_pos, "%.*x: ",
222				 map->debugfs_reg_len, i - from);
223			buf_pos += map->debugfs_reg_len + 2;
224
225			/* Format the value, write all X if we can't read */
226			ret = regmap_read(map, i, &val);
227			if (ret == 0)
228				snprintf(buf + buf_pos, count - buf_pos,
229					 "%.*x", map->debugfs_val_len, val);
230			else
231				memset(buf + buf_pos, 'X',
232				       map->debugfs_val_len);
233			buf_pos += 2 * map->format.val_bytes;
234
235			buf[buf_pos++] = '\n';
236		}
237		p += map->debugfs_tot_len;
238	}
239
240	ret = buf_pos;
241
242	if (copy_to_user(user_buf, buf, buf_pos)) {
243		ret = -EFAULT;
244		goto out;
245	}
246
247	*ppos += buf_pos;
248
249out:
250	kfree(buf);
251	return ret;
252}
253
254static ssize_t regmap_map_read_file(struct file *file, char __user *user_buf,
255				    size_t count, loff_t *ppos)
256{
257	struct regmap *map = file->private_data;
258
259	return regmap_read_debugfs(map, 0, map->max_register, user_buf,
260				   count, ppos);
261}
262
263#undef REGMAP_ALLOW_WRITE_DEBUGFS
264#ifdef REGMAP_ALLOW_WRITE_DEBUGFS
265/*
266 * This can be dangerous especially when we have clients such as
267 * PMICs, therefore don't provide any real compile time configuration option
268 * for this feature, people who want to use this will need to modify
269 * the source code directly.
270 */
271static ssize_t regmap_map_write_file(struct file *file,
272				     const char __user *user_buf,
273				     size_t count, loff_t *ppos)
274{
275	char buf[32];
276	size_t buf_size;
277	char *start = buf;
278	unsigned long reg, value;
279	struct regmap *map = file->private_data;
280	int ret;
281
282	buf_size = min(count, (sizeof(buf)-1));
283	if (copy_from_user(buf, user_buf, buf_size))
284		return -EFAULT;
285	buf[buf_size] = 0;
286
287	while (*start == ' ')
288		start++;
289	reg = simple_strtoul(start, &start, 16);
290	while (*start == ' ')
291		start++;
292	if (kstrtoul(start, 16, &value))
293		return -EINVAL;
294
295	/* Userspace has been fiddling around behind the kernel's back */
296	add_taint(TAINT_USER, LOCKDEP_STILL_OK);
297
298	ret = regmap_write(map, reg, value);
299	if (ret < 0)
300		return ret;
301	return buf_size;
302}
303#else
304#define regmap_map_write_file NULL
305#endif
306
307static const struct file_operations regmap_map_fops = {
308	.open = simple_open,
309	.read = regmap_map_read_file,
310	.write = regmap_map_write_file,
311	.llseek = default_llseek,
312};
313
314static ssize_t regmap_range_read_file(struct file *file, char __user *user_buf,
315				      size_t count, loff_t *ppos)
316{
317	struct regmap_range_node *range = file->private_data;
318	struct regmap *map = range->map;
319
320	return regmap_read_debugfs(map, range->range_min, range->range_max,
321				   user_buf, count, ppos);
322}
323
324static const struct file_operations regmap_range_fops = {
325	.open = simple_open,
326	.read = regmap_range_read_file,
327	.llseek = default_llseek,
328};
329
330static ssize_t regmap_reg_ranges_read_file(struct file *file,
331					   char __user *user_buf, size_t count,
332					   loff_t *ppos)
333{
334	struct regmap *map = file->private_data;
335	struct regmap_debugfs_off_cache *c;
336	loff_t p = 0;
337	size_t buf_pos = 0;
338	char *buf;
339	char *entry;
340	int ret;
341
342	if (*ppos < 0 || !count)
343		return -EINVAL;
344
345	buf = kmalloc(count, GFP_KERNEL);
346	if (!buf)
347		return -ENOMEM;
348
349	entry = kmalloc(PAGE_SIZE, GFP_KERNEL);
350	if (!entry) {
351		kfree(buf);
352		return -ENOMEM;
353	}
354
355	/* While we are at it, build the register dump cache
356	 * now so the read() operation on the `registers' file
357	 * can benefit from using the cache.  We do not care
358	 * about the file position information that is contained
359	 * in the cache, just about the actual register blocks */
360	regmap_calc_tot_len(map, buf, count);
361	regmap_debugfs_get_dump_start(map, 0, *ppos, &p);
362
363	/* Reset file pointer as the fixed-format of the `registers'
364	 * file is not compatible with the `range' file */
365	p = 0;
366	mutex_lock(&map->cache_lock);
367	list_for_each_entry(c, &map->debugfs_off_cache, list) {
368		snprintf(entry, PAGE_SIZE, "%x-%x",
369			 c->base_reg, c->max_reg);
370		if (p >= *ppos) {
371			if (buf_pos + 1 + strlen(entry) > count)
372				break;
373			snprintf(buf + buf_pos, count - buf_pos,
374				 "%s", entry);
375			buf_pos += strlen(entry);
376			buf[buf_pos] = '\n';
377			buf_pos++;
378		}
379		p += strlen(entry) + 1;
380	}
381	mutex_unlock(&map->cache_lock);
382
383	kfree(entry);
384	ret = buf_pos;
385
386	if (copy_to_user(user_buf, buf, buf_pos)) {
387		ret = -EFAULT;
388		goto out_buf;
389	}
390
391	*ppos += buf_pos;
392out_buf:
393	kfree(buf);
394	return ret;
395}
396
397static const struct file_operations regmap_reg_ranges_fops = {
398	.open = simple_open,
399	.read = regmap_reg_ranges_read_file,
400	.llseek = default_llseek,
401};
402
403static ssize_t regmap_access_read_file(struct file *file,
404				       char __user *user_buf, size_t count,
405				       loff_t *ppos)
406{
407	int reg_len, tot_len;
408	size_t buf_pos = 0;
409	loff_t p = 0;
410	ssize_t ret;
411	int i;
412	struct regmap *map = file->private_data;
413	char *buf;
414
415	if (*ppos < 0 || !count)
416		return -EINVAL;
417
418	buf = kmalloc(count, GFP_KERNEL);
419	if (!buf)
420		return -ENOMEM;
421
422	/* Calculate the length of a fixed format  */
423	reg_len = regmap_calc_reg_len(map->max_register, buf, count);
424	tot_len = reg_len + 10; /* ': R W V P\n' */
425
426	for (i = 0; i <= map->max_register; i += map->reg_stride) {
427		/* Ignore registers which are neither readable nor writable */
428		if (!regmap_readable(map, i) && !regmap_writeable(map, i))
429			continue;
430
431		/* If we're in the region the user is trying to read */
432		if (p >= *ppos) {
433			/* ...but not beyond it */
434			if (buf_pos + tot_len + 1 >= count)
435				break;
436
437			/* Format the register */
438			snprintf(buf + buf_pos, count - buf_pos,
439				 "%.*x: %c %c %c %c\n",
440				 reg_len, i,
441				 regmap_readable(map, i) ? 'y' : 'n',
442				 regmap_writeable(map, i) ? 'y' : 'n',
443				 regmap_volatile(map, i) ? 'y' : 'n',
444				 regmap_precious(map, i) ? 'y' : 'n');
445
446			buf_pos += tot_len;
447		}
448		p += tot_len;
449	}
450
451	ret = buf_pos;
452
453	if (copy_to_user(user_buf, buf, buf_pos)) {
454		ret = -EFAULT;
455		goto out;
456	}
457
458	*ppos += buf_pos;
459
460out:
461	kfree(buf);
462	return ret;
463}
464
465static const struct file_operations regmap_access_fops = {
466	.open = simple_open,
467	.read = regmap_access_read_file,
468	.llseek = default_llseek,
469};
470
471void regmap_debugfs_init(struct regmap *map, const char *name)
472{
473	struct rb_node *next;
474	struct regmap_range_node *range_node;
475	const char *devname = "dummy";
476
477	/* If we don't have the debugfs root yet, postpone init */
478	if (!regmap_debugfs_root) {
479		struct regmap_debugfs_node *node;
480		node = kzalloc(sizeof(*node), GFP_KERNEL);
481		if (!node)
482			return;
483		node->map = map;
484		node->name = name;
485		mutex_lock(&regmap_debugfs_early_lock);
486		list_add(&node->link, &regmap_debugfs_early_list);
487		mutex_unlock(&regmap_debugfs_early_lock);
488		return;
489	}
490
491	INIT_LIST_HEAD(&map->debugfs_off_cache);
492	mutex_init(&map->cache_lock);
493
494	if (map->dev)
495		devname = dev_name(map->dev);
496
497	if (name) {
498		map->debugfs_name = kasprintf(GFP_KERNEL, "%s-%s",
499					      devname, name);
500		name = map->debugfs_name;
501	} else {
502		name = devname;
503	}
504
505	map->debugfs = debugfs_create_dir(name, regmap_debugfs_root);
506	if (!map->debugfs) {
507		dev_warn(map->dev, "Failed to create debugfs directory\n");
508		return;
509	}
510
511	debugfs_create_file("name", 0400, map->debugfs,
512			    map, &regmap_name_fops);
513
514	debugfs_create_file("range", 0400, map->debugfs,
515			    map, &regmap_reg_ranges_fops);
516
517	if (map->max_register || regmap_readable(map, 0)) {
518		umode_t registers_mode;
519
520		if (IS_ENABLED(REGMAP_ALLOW_WRITE_DEBUGFS))
521			registers_mode = 0600;
522		else
523			registers_mode = 0400;
524
525		debugfs_create_file("registers", registers_mode, map->debugfs,
526				    map, &regmap_map_fops);
527		debugfs_create_file("access", 0400, map->debugfs,
528				    map, &regmap_access_fops);
529	}
530
531	if (map->cache_type) {
532		debugfs_create_bool("cache_only", 0400, map->debugfs,
533				    &map->cache_only);
534		debugfs_create_bool("cache_dirty", 0400, map->debugfs,
535				    &map->cache_dirty);
536		debugfs_create_bool("cache_bypass", 0400, map->debugfs,
537				    &map->cache_bypass);
538	}
539
540	next = rb_first(&map->range_tree);
541	while (next) {
542		range_node = rb_entry(next, struct regmap_range_node, node);
543
544		if (range_node->name)
545			debugfs_create_file(range_node->name, 0400,
546					    map->debugfs, range_node,
547					    &regmap_range_fops);
548
549		next = rb_next(&range_node->node);
550	}
551
552	if (map->cache_ops && map->cache_ops->debugfs_init)
553		map->cache_ops->debugfs_init(map);
554}
555
556void regmap_debugfs_exit(struct regmap *map)
557{
558	if (map->debugfs) {
559		debugfs_remove_recursive(map->debugfs);
560		mutex_lock(&map->cache_lock);
561		regmap_debugfs_free_dump_cache(map);
562		mutex_unlock(&map->cache_lock);
563		kfree(map->debugfs_name);
564	} else {
565		struct regmap_debugfs_node *node, *tmp;
566
567		mutex_lock(&regmap_debugfs_early_lock);
568		list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list,
569					 link) {
570			if (node->map == map) {
571				list_del(&node->link);
572				kfree(node);
573			}
574		}
575		mutex_unlock(&regmap_debugfs_early_lock);
576	}
577}
578
579void regmap_debugfs_initcall(void)
580{
581	struct regmap_debugfs_node *node, *tmp;
582
583	regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
584	if (!regmap_debugfs_root) {
585		pr_warn("regmap: Failed to create debugfs root\n");
586		return;
587	}
588
589	mutex_lock(&regmap_debugfs_early_lock);
590	list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list, link) {
591		regmap_debugfs_init(node->map, node->name);
592		list_del(&node->link);
593		kfree(node);
594	}
595	mutex_unlock(&regmap_debugfs_early_lock);
596}
597