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)
 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		map->debugfs_val_len = 2 * map->format.val_bytes;
178		map->debugfs_tot_len = map->debugfs_reg_len +
179			map->debugfs_val_len + 3;      /* : \n */
180	}
181}
182
183static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
184				   unsigned int to, char __user *user_buf,
185				   size_t count, loff_t *ppos)
186{
187	size_t buf_pos = 0;
188	loff_t p = *ppos;
189	ssize_t ret;
190	int i;
191	char *buf;
192	unsigned int val, start_reg;
193
194	if (*ppos < 0 || !count)
195		return -EINVAL;
196
197	buf = kmalloc(count, GFP_KERNEL);
198	if (!buf)
199		return -ENOMEM;
200
201	regmap_calc_tot_len(map, buf, count);
202
203	/* Work out which register we're starting at */
204	start_reg = regmap_debugfs_get_dump_start(map, from, *ppos, &p);
205
206	for (i = start_reg; i <= to; i += map->reg_stride) {
207		if (!regmap_readable(map, i))
208			continue;
209
210		if (regmap_precious(map, i))
211			continue;
212
213		/* If we're in the region the user is trying to read */
214		if (p >= *ppos) {
215			/* ...but not beyond it */
216			if (buf_pos + map->debugfs_tot_len > count)
217				break;
218
219			/* Format the register */
220			snprintf(buf + buf_pos, count - buf_pos, "%.*x: ",
221				 map->debugfs_reg_len, i - from);
222			buf_pos += map->debugfs_reg_len + 2;
223
224			/* Format the value, write all X if we can't read */
225			ret = regmap_read(map, i, &val);
226			if (ret == 0)
227				snprintf(buf + buf_pos, count - buf_pos,
228					 "%.*x", map->debugfs_val_len, val);
229			else
230				memset(buf + buf_pos, 'X',
231				       map->debugfs_val_len);
232			buf_pos += 2 * map->format.val_bytes;
233
234			buf[buf_pos++] = '\n';
235		}
236		p += map->debugfs_tot_len;
237	}
238
239	ret = buf_pos;
240
241	if (copy_to_user(user_buf, buf, buf_pos)) {
242		ret = -EFAULT;
243		goto out;
244	}
245
246	*ppos += buf_pos;
247
248out:
249	kfree(buf);
250	return ret;
251}
252
253static ssize_t regmap_map_read_file(struct file *file, char __user *user_buf,
254				    size_t count, loff_t *ppos)
255{
256	struct regmap *map = file->private_data;
257
258	return regmap_read_debugfs(map, 0, map->max_register, user_buf,
259				   count, ppos);
260}
261
262#undef REGMAP_ALLOW_WRITE_DEBUGFS
263#ifdef REGMAP_ALLOW_WRITE_DEBUGFS
264/*
265 * This can be dangerous especially when we have clients such as
266 * PMICs, therefore don't provide any real compile time configuration option
267 * for this feature, people who want to use this will need to modify
268 * the source code directly.
269 */
270static ssize_t regmap_map_write_file(struct file *file,
271				     const char __user *user_buf,
272				     size_t count, loff_t *ppos)
273{
274	char buf[32];
275	size_t buf_size;
276	char *start = buf;
277	unsigned long reg, value;
278	struct regmap *map = file->private_data;
279	int ret;
280
281	buf_size = min(count, (sizeof(buf)-1));
282	if (copy_from_user(buf, user_buf, buf_size))
283		return -EFAULT;
284	buf[buf_size] = 0;
285
286	while (*start == ' ')
287		start++;
288	reg = simple_strtoul(start, &start, 16);
289	while (*start == ' ')
290		start++;
291	if (kstrtoul(start, 16, &value))
292		return -EINVAL;
293
294	/* Userspace has been fiddling around behind the kernel's back */
295	add_taint(TAINT_USER, LOCKDEP_STILL_OK);
296
297	ret = regmap_write(map, reg, value);
298	if (ret < 0)
299		return ret;
300	return buf_size;
301}
302#else
303#define regmap_map_write_file NULL
304#endif
305
306static const struct file_operations regmap_map_fops = {
307	.open = simple_open,
308	.read = regmap_map_read_file,
309	.write = regmap_map_write_file,
310	.llseek = default_llseek,
311};
312
313static ssize_t regmap_range_read_file(struct file *file, char __user *user_buf,
314				      size_t count, loff_t *ppos)
315{
316	struct regmap_range_node *range = file->private_data;
317	struct regmap *map = range->map;
318
319	return regmap_read_debugfs(map, range->range_min, range->range_max,
320				   user_buf, count, ppos);
321}
322
323static const struct file_operations regmap_range_fops = {
324	.open = simple_open,
325	.read = regmap_range_read_file,
326	.llseek = default_llseek,
327};
328
329static ssize_t regmap_reg_ranges_read_file(struct file *file,
330					   char __user *user_buf, size_t count,
331					   loff_t *ppos)
332{
333	struct regmap *map = file->private_data;
334	struct regmap_debugfs_off_cache *c;
335	loff_t p = 0;
336	size_t buf_pos = 0;
337	char *buf;
338	char *entry;
339	int ret;
340	unsigned entry_len;
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		entry_len = snprintf(entry, PAGE_SIZE, "%x-%x\n",
369				     c->base_reg, c->max_reg);
370		if (p >= *ppos) {
371			if (buf_pos + entry_len > count)
372				break;
373			memcpy(buf + buf_pos, entry, entry_len);
374			buf_pos += entry_len;
375		}
376		p += entry_len;
377	}
378	mutex_unlock(&map->cache_lock);
379
380	kfree(entry);
381	ret = buf_pos;
382
383	if (copy_to_user(user_buf, buf, buf_pos)) {
384		ret = -EFAULT;
385		goto out_buf;
386	}
387
388	*ppos += buf_pos;
389out_buf:
390	kfree(buf);
391	return ret;
392}
393
394static const struct file_operations regmap_reg_ranges_fops = {
395	.open = simple_open,
396	.read = regmap_reg_ranges_read_file,
397	.llseek = default_llseek,
398};
399
400static int regmap_access_show(struct seq_file *s, void *ignored)
401{
402	struct regmap *map = s->private;
403	int i, reg_len;
404
405	reg_len = regmap_calc_reg_len(map->max_register);
406
407	for (i = 0; i <= map->max_register; i += map->reg_stride) {
408		/* Ignore registers which are neither readable nor writable */
409		if (!regmap_readable(map, i) && !regmap_writeable(map, i))
410			continue;
411
412		/* Format the register */
413		seq_printf(s, "%.*x: %c %c %c %c\n", reg_len, i,
414			   regmap_readable(map, i) ? 'y' : 'n',
415			   regmap_writeable(map, i) ? 'y' : 'n',
416			   regmap_volatile(map, i) ? 'y' : 'n',
417			   regmap_precious(map, i) ? 'y' : 'n');
418	}
419
420	return 0;
421}
422
423static int access_open(struct inode *inode, struct file *file)
424{
425	return single_open(file, regmap_access_show, inode->i_private);
426}
427
428static const struct file_operations regmap_access_fops = {
429	.open		= access_open,
430	.read		= seq_read,
431	.llseek		= seq_lseek,
432	.release	= single_release,
433};
434
435static ssize_t regmap_cache_only_write_file(struct file *file,
436					    const char __user *user_buf,
437					    size_t count, loff_t *ppos)
438{
439	struct regmap *map = container_of(file->private_data,
440					  struct regmap, cache_only);
441	ssize_t result;
442	bool was_enabled, require_sync = false;
443	int err;
444
445	map->lock(map->lock_arg);
446
447	was_enabled = map->cache_only;
448
449	result = debugfs_write_file_bool(file, user_buf, count, ppos);
450	if (result < 0) {
451		map->unlock(map->lock_arg);
452		return result;
453	}
454
455	if (map->cache_only && !was_enabled) {
456		dev_warn(map->dev, "debugfs cache_only=Y forced\n");
457		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
458	} else if (!map->cache_only && was_enabled) {
459		dev_warn(map->dev, "debugfs cache_only=N forced: syncing cache\n");
460		require_sync = true;
461	}
462
463	map->unlock(map->lock_arg);
464
465	if (require_sync) {
466		err = regcache_sync(map);
467		if (err)
468			dev_err(map->dev, "Failed to sync cache %d\n", err);
469	}
470
471	return result;
472}
473
474static const struct file_operations regmap_cache_only_fops = {
475	.open = simple_open,
476	.read = debugfs_read_file_bool,
477	.write = regmap_cache_only_write_file,
478};
479
480static ssize_t regmap_cache_bypass_write_file(struct file *file,
481					      const char __user *user_buf,
482					      size_t count, loff_t *ppos)
483{
484	struct regmap *map = container_of(file->private_data,
485					  struct regmap, cache_bypass);
486	ssize_t result;
487	bool was_enabled;
488
489	map->lock(map->lock_arg);
490
491	was_enabled = map->cache_bypass;
492
493	result = debugfs_write_file_bool(file, user_buf, count, ppos);
494	if (result < 0)
495		goto out;
496
497	if (map->cache_bypass && !was_enabled) {
498		dev_warn(map->dev, "debugfs cache_bypass=Y forced\n");
499		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
500	} else if (!map->cache_bypass && was_enabled) {
501		dev_warn(map->dev, "debugfs cache_bypass=N forced\n");
502	}
503
504out:
505	map->unlock(map->lock_arg);
506
507	return result;
508}
509
510static const struct file_operations regmap_cache_bypass_fops = {
511	.open = simple_open,
512	.read = debugfs_read_file_bool,
513	.write = regmap_cache_bypass_write_file,
514};
515
516void regmap_debugfs_init(struct regmap *map, const char *name)
517{
518	struct rb_node *next;
519	struct regmap_range_node *range_node;
520	const char *devname = "dummy";
521
522	/* If we don't have the debugfs root yet, postpone init */
523	if (!regmap_debugfs_root) {
524		struct regmap_debugfs_node *node;
525		node = kzalloc(sizeof(*node), GFP_KERNEL);
526		if (!node)
527			return;
528		node->map = map;
529		node->name = name;
530		mutex_lock(&regmap_debugfs_early_lock);
531		list_add(&node->link, &regmap_debugfs_early_list);
532		mutex_unlock(&regmap_debugfs_early_lock);
533		return;
534	}
535
536	INIT_LIST_HEAD(&map->debugfs_off_cache);
537	mutex_init(&map->cache_lock);
538
539	if (map->dev)
540		devname = dev_name(map->dev);
541
542	if (name) {
543		map->debugfs_name = kasprintf(GFP_KERNEL, "%s-%s",
544					      devname, name);
545		name = map->debugfs_name;
546	} else {
547		name = devname;
548	}
549
550	map->debugfs = debugfs_create_dir(name, regmap_debugfs_root);
551	if (!map->debugfs) {
552		dev_warn(map->dev, "Failed to create debugfs directory\n");
553		return;
554	}
555
556	debugfs_create_file("name", 0400, map->debugfs,
557			    map, &regmap_name_fops);
558
559	debugfs_create_file("range", 0400, map->debugfs,
560			    map, &regmap_reg_ranges_fops);
561
562	if (map->max_register || regmap_readable(map, 0)) {
563		umode_t registers_mode;
564
565#if defined(REGMAP_ALLOW_WRITE_DEBUGFS)
566		registers_mode = 0600;
567#else
568		registers_mode = 0400;
569#endif
570
571		debugfs_create_file("registers", registers_mode, map->debugfs,
572				    map, &regmap_map_fops);
573		debugfs_create_file("access", 0400, map->debugfs,
574				    map, &regmap_access_fops);
575	}
576
577	if (map->cache_type) {
578		debugfs_create_file("cache_only", 0600, map->debugfs,
579				    &map->cache_only, &regmap_cache_only_fops);
580		debugfs_create_bool("cache_dirty", 0400, map->debugfs,
581				    &map->cache_dirty);
582		debugfs_create_file("cache_bypass", 0600, map->debugfs,
583				    &map->cache_bypass,
584				    &regmap_cache_bypass_fops);
585	}
586
587	next = rb_first(&map->range_tree);
588	while (next) {
589		range_node = rb_entry(next, struct regmap_range_node, node);
590
591		if (range_node->name)
592			debugfs_create_file(range_node->name, 0400,
593					    map->debugfs, range_node,
594					    &regmap_range_fops);
595
596		next = rb_next(&range_node->node);
597	}
598
599	if (map->cache_ops && map->cache_ops->debugfs_init)
600		map->cache_ops->debugfs_init(map);
601}
602
603void regmap_debugfs_exit(struct regmap *map)
604{
605	if (map->debugfs) {
606		debugfs_remove_recursive(map->debugfs);
607		mutex_lock(&map->cache_lock);
608		regmap_debugfs_free_dump_cache(map);
609		mutex_unlock(&map->cache_lock);
610		kfree(map->debugfs_name);
611	} else {
612		struct regmap_debugfs_node *node, *tmp;
613
614		mutex_lock(&regmap_debugfs_early_lock);
615		list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list,
616					 link) {
617			if (node->map == map) {
618				list_del(&node->link);
619				kfree(node);
620			}
621		}
622		mutex_unlock(&regmap_debugfs_early_lock);
623	}
624}
625
626void regmap_debugfs_initcall(void)
627{
628	struct regmap_debugfs_node *node, *tmp;
629
630	regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
631	if (!regmap_debugfs_root) {
632		pr_warn("regmap: Failed to create debugfs root\n");
633		return;
634	}
635
636	mutex_lock(&regmap_debugfs_early_lock);
637	list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list, link) {
638		regmap_debugfs_init(node->map, node->name);
639		list_del(&node->link);
640		kfree(node);
641	}
642	mutex_unlock(&regmap_debugfs_early_lock);
643}