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 
22 struct regmap_debugfs_node {
23 	struct regmap *map;
24 	const char *name;
25 	struct list_head link;
26 };
27 
28 static struct dentry *regmap_debugfs_root;
29 static LIST_HEAD(regmap_debugfs_early_list);
30 static DEFINE_MUTEX(regmap_debugfs_early_lock);
31 
32 /* Calculate the length of a fixed format  */
33 static 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 
39 static 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 
62 static const struct file_operations regmap_name_fops = {
63 	.open = simple_open,
64 	.read = regmap_name_read_file,
65 	.llseek = default_llseek,
66 };
67 
68 static 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  */
85 static 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 
172 static 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 
185 static 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 
250 out:
251 	kfree(buf);
252 	return ret;
253 }
254 
255 static 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  */
272 static 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 
308 static 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 
315 static 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 
325 static const struct file_operations regmap_range_fops = {
326 	.open = simple_open,
327 	.read = regmap_range_read_file,
328 	.llseek = default_llseek,
329 };
330 
331 static 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;
393 out_buf:
394 	kfree(buf);
395 	return ret;
396 }
397 
398 static 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 
404 static 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 
461 out:
462 	kfree(buf);
463 	return ret;
464 }
465 
466 static const struct file_operations regmap_access_fops = {
467 	.open = simple_open,
468 	.read = regmap_access_read_file,
469 	.llseek = default_llseek,
470 };
471 
472 void regmap_debugfs_init(struct regmap *map, const char *name)
473 {
474 	struct rb_node *next;
475 	struct regmap_range_node *range_node;
476 	const char *devname = "dummy";
477 
478 	/* If we don't have the debugfs root yet, postpone init */
479 	if (!regmap_debugfs_root) {
480 		struct regmap_debugfs_node *node;
481 		node = kzalloc(sizeof(*node), GFP_KERNEL);
482 		if (!node)
483 			return;
484 		node->map = map;
485 		node->name = name;
486 		mutex_lock(&regmap_debugfs_early_lock);
487 		list_add(&node->link, &regmap_debugfs_early_list);
488 		mutex_unlock(&regmap_debugfs_early_lock);
489 		return;
490 	}
491 
492 	INIT_LIST_HEAD(&map->debugfs_off_cache);
493 	mutex_init(&map->cache_lock);
494 
495 	if (map->dev)
496 		devname = dev_name(map->dev);
497 
498 	if (name) {
499 		map->debugfs_name = kasprintf(GFP_KERNEL, "%s-%s",
500 					      devname, name);
501 		name = map->debugfs_name;
502 	} else {
503 		name = devname;
504 	}
505 
506 	map->debugfs = debugfs_create_dir(name, regmap_debugfs_root);
507 	if (!map->debugfs) {
508 		dev_warn(map->dev, "Failed to create debugfs directory\n");
509 		return;
510 	}
511 
512 	debugfs_create_file("name", 0400, map->debugfs,
513 			    map, &regmap_name_fops);
514 
515 	debugfs_create_file("range", 0400, map->debugfs,
516 			    map, &regmap_reg_ranges_fops);
517 
518 	if (map->max_register || regmap_readable(map, 0)) {
519 		umode_t registers_mode;
520 
521 		if (IS_ENABLED(REGMAP_ALLOW_WRITE_DEBUGFS))
522 			registers_mode = 0600;
523 		else
524 			registers_mode = 0400;
525 
526 		debugfs_create_file("registers", registers_mode, map->debugfs,
527 				    map, &regmap_map_fops);
528 		debugfs_create_file("access", 0400, map->debugfs,
529 				    map, &regmap_access_fops);
530 	}
531 
532 	if (map->cache_type) {
533 		debugfs_create_bool("cache_only", 0400, map->debugfs,
534 				    &map->cache_only);
535 		debugfs_create_bool("cache_dirty", 0400, map->debugfs,
536 				    &map->cache_dirty);
537 		debugfs_create_bool("cache_bypass", 0400, map->debugfs,
538 				    &map->cache_bypass);
539 	}
540 
541 	next = rb_first(&map->range_tree);
542 	while (next) {
543 		range_node = rb_entry(next, struct regmap_range_node, node);
544 
545 		if (range_node->name)
546 			debugfs_create_file(range_node->name, 0400,
547 					    map->debugfs, range_node,
548 					    &regmap_range_fops);
549 
550 		next = rb_next(&range_node->node);
551 	}
552 
553 	if (map->cache_ops && map->cache_ops->debugfs_init)
554 		map->cache_ops->debugfs_init(map);
555 }
556 
557 void regmap_debugfs_exit(struct regmap *map)
558 {
559 	if (map->debugfs) {
560 		debugfs_remove_recursive(map->debugfs);
561 		mutex_lock(&map->cache_lock);
562 		regmap_debugfs_free_dump_cache(map);
563 		mutex_unlock(&map->cache_lock);
564 		kfree(map->debugfs_name);
565 	} else {
566 		struct regmap_debugfs_node *node, *tmp;
567 
568 		mutex_lock(&regmap_debugfs_early_lock);
569 		list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list,
570 					 link) {
571 			if (node->map == map) {
572 				list_del(&node->link);
573 				kfree(node);
574 			}
575 		}
576 		mutex_unlock(&regmap_debugfs_early_lock);
577 	}
578 }
579 
580 void regmap_debugfs_initcall(void)
581 {
582 	struct regmap_debugfs_node *node, *tmp;
583 
584 	regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
585 	if (!regmap_debugfs_root) {
586 		pr_warn("regmap: Failed to create debugfs root\n");
587 		return;
588 	}
589 
590 	mutex_lock(&regmap_debugfs_early_lock);
591 	list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list, link) {
592 		regmap_debugfs_init(node->map, node->name);
593 		list_del(&node->link);
594 		kfree(node);
595 	}
596 	mutex_unlock(&regmap_debugfs_early_lock);
597 }
598