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