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 
18 struct regmap_debugfs_node {
19 	struct regmap *map;
20 	const char *name;
21 	struct list_head link;
22 };
23 
24 static unsigned int dummy_index;
25 static struct dentry *regmap_debugfs_root;
26 static LIST_HEAD(regmap_debugfs_early_list);
27 static DEFINE_MUTEX(regmap_debugfs_early_lock);
28 
29 /* Calculate the length of a fixed format  */
30 static size_t regmap_calc_reg_len(int max_val)
31 {
32 	return snprintf(NULL, 0, "%x", max_val);
33 }
34 
35 static ssize_t regmap_name_read_file(struct file *file,
36 				     char __user *user_buf, size_t count,
37 				     loff_t *ppos)
38 {
39 	struct regmap *map = file->private_data;
40 	const char *name = "nodev";
41 	int ret;
42 	char *buf;
43 
44 	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
45 	if (!buf)
46 		return -ENOMEM;
47 
48 	if (map->dev && map->dev->driver)
49 		name = map->dev->driver->name;
50 
51 	ret = snprintf(buf, PAGE_SIZE, "%s\n", 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 static bool regmap_printable(struct regmap *map, unsigned int reg)
82 {
83 	if (regmap_precious(map, reg))
84 		return false;
85 
86 	if (!regmap_readable(map, reg) && !regmap_cached(map, reg))
87 		return false;
88 
89 	return true;
90 }
91 
92 /*
93  * Work out where the start offset maps into register numbers, bearing
94  * in mind that we suppress hidden registers.
95  */
96 static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
97 						  unsigned int base,
98 						  loff_t from,
99 						  loff_t *pos)
100 {
101 	struct regmap_debugfs_off_cache *c = NULL;
102 	loff_t p = 0;
103 	unsigned int i, ret;
104 	unsigned int fpos_offset;
105 	unsigned int reg_offset;
106 
107 	/* Suppress the cache if we're using a subrange */
108 	if (base)
109 		return base;
110 
111 	/*
112 	 * If we don't have a cache build one so we don't have to do a
113 	 * linear scan each time.
114 	 */
115 	mutex_lock(&map->cache_lock);
116 	i = base;
117 	if (list_empty(&map->debugfs_off_cache)) {
118 		for (; i <= map->max_register; i += map->reg_stride) {
119 			/* Skip unprinted registers, closing off cache entry */
120 			if (!regmap_printable(map, i)) {
121 				if (c) {
122 					c->max = p - 1;
123 					c->max_reg = i - map->reg_stride;
124 					list_add_tail(&c->list,
125 						      &map->debugfs_off_cache);
126 					c = NULL;
127 				}
128 
129 				continue;
130 			}
131 
132 			/* No cache entry?  Start a new one */
133 			if (!c) {
134 				c = kzalloc(sizeof(*c), GFP_KERNEL);
135 				if (!c) {
136 					regmap_debugfs_free_dump_cache(map);
137 					mutex_unlock(&map->cache_lock);
138 					return base;
139 				}
140 				c->min = p;
141 				c->base_reg = i;
142 			}
143 
144 			p += map->debugfs_tot_len;
145 		}
146 	}
147 
148 	/* Close the last entry off if we didn't scan beyond it */
149 	if (c) {
150 		c->max = p - 1;
151 		c->max_reg = i - map->reg_stride;
152 		list_add_tail(&c->list,
153 			      &map->debugfs_off_cache);
154 	}
155 
156 	/*
157 	 * This should never happen; we return above if we fail to
158 	 * allocate and we should never be in this code if there are
159 	 * no registers at all.
160 	 */
161 	WARN_ON(list_empty(&map->debugfs_off_cache));
162 	ret = base;
163 
164 	/* Find the relevant block:offset */
165 	list_for_each_entry(c, &map->debugfs_off_cache, list) {
166 		if (from >= c->min && from <= c->max) {
167 			fpos_offset = from - c->min;
168 			reg_offset = fpos_offset / map->debugfs_tot_len;
169 			*pos = c->min + (reg_offset * map->debugfs_tot_len);
170 			mutex_unlock(&map->cache_lock);
171 			return c->base_reg + (reg_offset * map->reg_stride);
172 		}
173 
174 		*pos = c->max;
175 		ret = c->max_reg;
176 	}
177 	mutex_unlock(&map->cache_lock);
178 
179 	return ret;
180 }
181 
182 static inline void regmap_calc_tot_len(struct regmap *map,
183 				       void *buf, size_t count)
184 {
185 	/* Calculate the length of a fixed format  */
186 	if (!map->debugfs_tot_len) {
187 		map->debugfs_reg_len = regmap_calc_reg_len(map->max_register),
188 		map->debugfs_val_len = 2 * map->format.val_bytes;
189 		map->debugfs_tot_len = map->debugfs_reg_len +
190 			map->debugfs_val_len + 3;      /* : \n */
191 	}
192 }
193 
194 static int regmap_next_readable_reg(struct regmap *map, int reg)
195 {
196 	struct regmap_debugfs_off_cache *c;
197 	int ret = -EINVAL;
198 
199 	if (regmap_printable(map, reg + map->reg_stride)) {
200 		ret = reg + map->reg_stride;
201 	} else {
202 		mutex_lock(&map->cache_lock);
203 		list_for_each_entry(c, &map->debugfs_off_cache, list) {
204 			if (reg > c->max_reg)
205 				continue;
206 			if (reg < c->base_reg) {
207 				ret = c->base_reg;
208 				break;
209 			}
210 		}
211 		mutex_unlock(&map->cache_lock);
212 	}
213 	return ret;
214 }
215 
216 static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
217 				   unsigned int to, char __user *user_buf,
218 				   size_t count, loff_t *ppos)
219 {
220 	size_t buf_pos = 0;
221 	loff_t p = *ppos;
222 	ssize_t ret;
223 	int i;
224 	char *buf;
225 	unsigned int val, start_reg;
226 
227 	if (*ppos < 0 || !count)
228 		return -EINVAL;
229 
230 	buf = kmalloc(count, GFP_KERNEL);
231 	if (!buf)
232 		return -ENOMEM;
233 
234 	regmap_calc_tot_len(map, buf, count);
235 
236 	/* Work out which register we're starting at */
237 	start_reg = regmap_debugfs_get_dump_start(map, from, *ppos, &p);
238 
239 	for (i = start_reg; i >= 0 && i <= to;
240 	     i = regmap_next_readable_reg(map, i)) {
241 
242 		/* If we're in the region the user is trying to read */
243 		if (p >= *ppos) {
244 			/* ...but not beyond it */
245 			if (buf_pos + map->debugfs_tot_len > count)
246 				break;
247 
248 			/* Format the register */
249 			snprintf(buf + buf_pos, count - buf_pos, "%.*x: ",
250 				 map->debugfs_reg_len, i - from);
251 			buf_pos += map->debugfs_reg_len + 2;
252 
253 			/* Format the value, write all X if we can't read */
254 			ret = regmap_read(map, i, &val);
255 			if (ret == 0)
256 				snprintf(buf + buf_pos, count - buf_pos,
257 					 "%.*x", map->debugfs_val_len, val);
258 			else
259 				memset(buf + buf_pos, 'X',
260 				       map->debugfs_val_len);
261 			buf_pos += 2 * map->format.val_bytes;
262 
263 			buf[buf_pos++] = '\n';
264 		}
265 		p += map->debugfs_tot_len;
266 	}
267 
268 	ret = buf_pos;
269 
270 	if (copy_to_user(user_buf, buf, buf_pos)) {
271 		ret = -EFAULT;
272 		goto out;
273 	}
274 
275 	*ppos += buf_pos;
276 
277 out:
278 	kfree(buf);
279 	return ret;
280 }
281 
282 static ssize_t regmap_map_read_file(struct file *file, char __user *user_buf,
283 				    size_t count, loff_t *ppos)
284 {
285 	struct regmap *map = file->private_data;
286 
287 	return regmap_read_debugfs(map, 0, map->max_register, user_buf,
288 				   count, ppos);
289 }
290 
291 #undef REGMAP_ALLOW_WRITE_DEBUGFS
292 #ifdef REGMAP_ALLOW_WRITE_DEBUGFS
293 /*
294  * This can be dangerous especially when we have clients such as
295  * PMICs, therefore don't provide any real compile time configuration option
296  * for this feature, people who want to use this will need to modify
297  * the source code directly.
298  */
299 static ssize_t regmap_map_write_file(struct file *file,
300 				     const char __user *user_buf,
301 				     size_t count, loff_t *ppos)
302 {
303 	char buf[32];
304 	size_t buf_size;
305 	char *start = buf;
306 	unsigned long reg, value;
307 	struct regmap *map = file->private_data;
308 	int ret;
309 
310 	buf_size = min(count, (sizeof(buf)-1));
311 	if (copy_from_user(buf, user_buf, buf_size))
312 		return -EFAULT;
313 	buf[buf_size] = 0;
314 
315 	while (*start == ' ')
316 		start++;
317 	reg = simple_strtoul(start, &start, 16);
318 	while (*start == ' ')
319 		start++;
320 	if (kstrtoul(start, 16, &value))
321 		return -EINVAL;
322 
323 	/* Userspace has been fiddling around behind the kernel's back */
324 	add_taint(TAINT_USER, LOCKDEP_STILL_OK);
325 
326 	ret = regmap_write(map, reg, value);
327 	if (ret < 0)
328 		return ret;
329 	return buf_size;
330 }
331 #else
332 #define regmap_map_write_file NULL
333 #endif
334 
335 static const struct file_operations regmap_map_fops = {
336 	.open = simple_open,
337 	.read = regmap_map_read_file,
338 	.write = regmap_map_write_file,
339 	.llseek = default_llseek,
340 };
341 
342 static ssize_t regmap_range_read_file(struct file *file, char __user *user_buf,
343 				      size_t count, loff_t *ppos)
344 {
345 	struct regmap_range_node *range = file->private_data;
346 	struct regmap *map = range->map;
347 
348 	return regmap_read_debugfs(map, range->range_min, range->range_max,
349 				   user_buf, count, ppos);
350 }
351 
352 static const struct file_operations regmap_range_fops = {
353 	.open = simple_open,
354 	.read = regmap_range_read_file,
355 	.llseek = default_llseek,
356 };
357 
358 static ssize_t regmap_reg_ranges_read_file(struct file *file,
359 					   char __user *user_buf, size_t count,
360 					   loff_t *ppos)
361 {
362 	struct regmap *map = file->private_data;
363 	struct regmap_debugfs_off_cache *c;
364 	loff_t p = 0;
365 	size_t buf_pos = 0;
366 	char *buf;
367 	char *entry;
368 	int ret;
369 	unsigned entry_len;
370 
371 	if (*ppos < 0 || !count)
372 		return -EINVAL;
373 
374 	buf = kmalloc(count, GFP_KERNEL);
375 	if (!buf)
376 		return -ENOMEM;
377 
378 	entry = kmalloc(PAGE_SIZE, GFP_KERNEL);
379 	if (!entry) {
380 		kfree(buf);
381 		return -ENOMEM;
382 	}
383 
384 	/* While we are at it, build the register dump cache
385 	 * now so the read() operation on the `registers' file
386 	 * can benefit from using the cache.  We do not care
387 	 * about the file position information that is contained
388 	 * in the cache, just about the actual register blocks */
389 	regmap_calc_tot_len(map, buf, count);
390 	regmap_debugfs_get_dump_start(map, 0, *ppos, &p);
391 
392 	/* Reset file pointer as the fixed-format of the `registers'
393 	 * file is not compatible with the `range' file */
394 	p = 0;
395 	mutex_lock(&map->cache_lock);
396 	list_for_each_entry(c, &map->debugfs_off_cache, list) {
397 		entry_len = snprintf(entry, PAGE_SIZE, "%x-%x\n",
398 				     c->base_reg, c->max_reg);
399 		if (p >= *ppos) {
400 			if (buf_pos + entry_len > count)
401 				break;
402 			memcpy(buf + buf_pos, entry, entry_len);
403 			buf_pos += entry_len;
404 		}
405 		p += entry_len;
406 	}
407 	mutex_unlock(&map->cache_lock);
408 
409 	kfree(entry);
410 	ret = buf_pos;
411 
412 	if (copy_to_user(user_buf, buf, buf_pos)) {
413 		ret = -EFAULT;
414 		goto out_buf;
415 	}
416 
417 	*ppos += buf_pos;
418 out_buf:
419 	kfree(buf);
420 	return ret;
421 }
422 
423 static const struct file_operations regmap_reg_ranges_fops = {
424 	.open = simple_open,
425 	.read = regmap_reg_ranges_read_file,
426 	.llseek = default_llseek,
427 };
428 
429 static int regmap_access_show(struct seq_file *s, void *ignored)
430 {
431 	struct regmap *map = s->private;
432 	int i, reg_len;
433 
434 	reg_len = regmap_calc_reg_len(map->max_register);
435 
436 	for (i = 0; i <= map->max_register; i += map->reg_stride) {
437 		/* Ignore registers which are neither readable nor writable */
438 		if (!regmap_readable(map, i) && !regmap_writeable(map, i))
439 			continue;
440 
441 		/* Format the register */
442 		seq_printf(s, "%.*x: %c %c %c %c\n", reg_len, i,
443 			   regmap_readable(map, i) ? 'y' : 'n',
444 			   regmap_writeable(map, i) ? 'y' : 'n',
445 			   regmap_volatile(map, i) ? 'y' : 'n',
446 			   regmap_precious(map, i) ? 'y' : 'n');
447 	}
448 
449 	return 0;
450 }
451 
452 DEFINE_SHOW_ATTRIBUTE(regmap_access);
453 
454 static ssize_t regmap_cache_only_write_file(struct file *file,
455 					    const char __user *user_buf,
456 					    size_t count, loff_t *ppos)
457 {
458 	struct regmap *map = container_of(file->private_data,
459 					  struct regmap, cache_only);
460 	ssize_t result;
461 	bool was_enabled, require_sync = false;
462 	int err;
463 
464 	map->lock(map->lock_arg);
465 
466 	was_enabled = map->cache_only;
467 
468 	result = debugfs_write_file_bool(file, user_buf, count, ppos);
469 	if (result < 0) {
470 		map->unlock(map->lock_arg);
471 		return result;
472 	}
473 
474 	if (map->cache_only && !was_enabled) {
475 		dev_warn(map->dev, "debugfs cache_only=Y forced\n");
476 		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
477 	} else if (!map->cache_only && was_enabled) {
478 		dev_warn(map->dev, "debugfs cache_only=N forced: syncing cache\n");
479 		require_sync = true;
480 	}
481 
482 	map->unlock(map->lock_arg);
483 
484 	if (require_sync) {
485 		err = regcache_sync(map);
486 		if (err)
487 			dev_err(map->dev, "Failed to sync cache %d\n", err);
488 	}
489 
490 	return result;
491 }
492 
493 static const struct file_operations regmap_cache_only_fops = {
494 	.open = simple_open,
495 	.read = debugfs_read_file_bool,
496 	.write = regmap_cache_only_write_file,
497 };
498 
499 static ssize_t regmap_cache_bypass_write_file(struct file *file,
500 					      const char __user *user_buf,
501 					      size_t count, loff_t *ppos)
502 {
503 	struct regmap *map = container_of(file->private_data,
504 					  struct regmap, cache_bypass);
505 	ssize_t result;
506 	bool was_enabled;
507 
508 	map->lock(map->lock_arg);
509 
510 	was_enabled = map->cache_bypass;
511 
512 	result = debugfs_write_file_bool(file, user_buf, count, ppos);
513 	if (result < 0)
514 		goto out;
515 
516 	if (map->cache_bypass && !was_enabled) {
517 		dev_warn(map->dev, "debugfs cache_bypass=Y forced\n");
518 		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
519 	} else if (!map->cache_bypass && was_enabled) {
520 		dev_warn(map->dev, "debugfs cache_bypass=N forced\n");
521 	}
522 
523 out:
524 	map->unlock(map->lock_arg);
525 
526 	return result;
527 }
528 
529 static const struct file_operations regmap_cache_bypass_fops = {
530 	.open = simple_open,
531 	.read = debugfs_read_file_bool,
532 	.write = regmap_cache_bypass_write_file,
533 };
534 
535 void regmap_debugfs_init(struct regmap *map, const char *name)
536 {
537 	struct rb_node *next;
538 	struct regmap_range_node *range_node;
539 	const char *devname = "dummy";
540 
541 	/*
542 	 * Userspace can initiate reads from the hardware over debugfs.
543 	 * Normally internal regmap structures and buffers are protected with
544 	 * a mutex or a spinlock, but if the regmap owner decided to disable
545 	 * all locking mechanisms, this is no longer the case. For safety:
546 	 * don't create the debugfs entries if locking is disabled.
547 	 */
548 	if (map->debugfs_disable) {
549 		dev_dbg(map->dev, "regmap locking disabled - not creating debugfs entries\n");
550 		return;
551 	}
552 
553 	/* If we don't have the debugfs root yet, postpone init */
554 	if (!regmap_debugfs_root) {
555 		struct regmap_debugfs_node *node;
556 		node = kzalloc(sizeof(*node), GFP_KERNEL);
557 		if (!node)
558 			return;
559 		node->map = map;
560 		node->name = name;
561 		mutex_lock(&regmap_debugfs_early_lock);
562 		list_add(&node->link, &regmap_debugfs_early_list);
563 		mutex_unlock(&regmap_debugfs_early_lock);
564 		return;
565 	}
566 
567 	INIT_LIST_HEAD(&map->debugfs_off_cache);
568 	mutex_init(&map->cache_lock);
569 
570 	if (map->dev)
571 		devname = dev_name(map->dev);
572 
573 	if (name) {
574 		map->debugfs_name = kasprintf(GFP_KERNEL, "%s-%s",
575 					      devname, name);
576 		name = map->debugfs_name;
577 	} else {
578 		name = devname;
579 	}
580 
581 	if (!strcmp(name, "dummy")) {
582 		kfree(map->debugfs_name);
583 
584 		map->debugfs_name = kasprintf(GFP_KERNEL, "dummy%d",
585 						dummy_index);
586 		name = map->debugfs_name;
587 		dummy_index++;
588 	}
589 
590 	map->debugfs = debugfs_create_dir(name, regmap_debugfs_root);
591 	if (!map->debugfs) {
592 		dev_warn(map->dev,
593 			 "Failed to create %s debugfs directory\n", name);
594 
595 		kfree(map->debugfs_name);
596 		map->debugfs_name = NULL;
597 		return;
598 	}
599 
600 	debugfs_create_file("name", 0400, map->debugfs,
601 			    map, &regmap_name_fops);
602 
603 	debugfs_create_file("range", 0400, map->debugfs,
604 			    map, &regmap_reg_ranges_fops);
605 
606 	if (map->max_register || regmap_readable(map, 0)) {
607 		umode_t registers_mode;
608 
609 #if defined(REGMAP_ALLOW_WRITE_DEBUGFS)
610 		registers_mode = 0600;
611 #else
612 		registers_mode = 0400;
613 #endif
614 
615 		debugfs_create_file("registers", registers_mode, map->debugfs,
616 				    map, &regmap_map_fops);
617 		debugfs_create_file("access", 0400, map->debugfs,
618 				    map, &regmap_access_fops);
619 	}
620 
621 	if (map->cache_type) {
622 		debugfs_create_file("cache_only", 0600, map->debugfs,
623 				    &map->cache_only, &regmap_cache_only_fops);
624 		debugfs_create_bool("cache_dirty", 0400, map->debugfs,
625 				    &map->cache_dirty);
626 		debugfs_create_file("cache_bypass", 0600, map->debugfs,
627 				    &map->cache_bypass,
628 				    &regmap_cache_bypass_fops);
629 	}
630 
631 	next = rb_first(&map->range_tree);
632 	while (next) {
633 		range_node = rb_entry(next, struct regmap_range_node, node);
634 
635 		if (range_node->name)
636 			debugfs_create_file(range_node->name, 0400,
637 					    map->debugfs, range_node,
638 					    &regmap_range_fops);
639 
640 		next = rb_next(&range_node->node);
641 	}
642 
643 	if (map->cache_ops && map->cache_ops->debugfs_init)
644 		map->cache_ops->debugfs_init(map);
645 }
646 
647 void regmap_debugfs_exit(struct regmap *map)
648 {
649 	if (map->debugfs) {
650 		debugfs_remove_recursive(map->debugfs);
651 		mutex_lock(&map->cache_lock);
652 		regmap_debugfs_free_dump_cache(map);
653 		mutex_unlock(&map->cache_lock);
654 		kfree(map->debugfs_name);
655 	} else {
656 		struct regmap_debugfs_node *node, *tmp;
657 
658 		mutex_lock(&regmap_debugfs_early_lock);
659 		list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list,
660 					 link) {
661 			if (node->map == map) {
662 				list_del(&node->link);
663 				kfree(node);
664 			}
665 		}
666 		mutex_unlock(&regmap_debugfs_early_lock);
667 	}
668 }
669 
670 void regmap_debugfs_initcall(void)
671 {
672 	struct regmap_debugfs_node *node, *tmp;
673 
674 	regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
675 	if (!regmap_debugfs_root) {
676 		pr_warn("regmap: Failed to create debugfs root\n");
677 		return;
678 	}
679 
680 	mutex_lock(&regmap_debugfs_early_lock);
681 	list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list, link) {
682 		regmap_debugfs_init(node->map, node->name);
683 		list_del(&node->link);
684 		kfree(node);
685 	}
686 	mutex_unlock(&regmap_debugfs_early_lock);
687 }
688