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 	struct list_head link;
21 };
22 
23 static unsigned int dummy_index;
24 static struct dentry *regmap_debugfs_root;
25 static LIST_HEAD(regmap_debugfs_early_list);
26 static DEFINE_MUTEX(regmap_debugfs_early_lock);
27 
28 /* Calculate the length of a fixed format  */
29 static size_t regmap_calc_reg_len(int max_val)
30 {
31 	return snprintf(NULL, 0, "%x", max_val);
32 }
33 
34 static ssize_t regmap_name_read_file(struct file *file,
35 				     char __user *user_buf, size_t count,
36 				     loff_t *ppos)
37 {
38 	struct regmap *map = file->private_data;
39 	const char *name = "nodev";
40 	int ret;
41 	char *buf;
42 
43 	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
44 	if (!buf)
45 		return -ENOMEM;
46 
47 	if (map->dev && map->dev->driver)
48 		name = map->dev->driver->name;
49 
50 	ret = snprintf(buf, PAGE_SIZE, "%s\n", 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 
61 static const struct file_operations regmap_name_fops = {
62 	.open = simple_open,
63 	.read = regmap_name_read_file,
64 	.llseek = default_llseek,
65 };
66 
67 static 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 static bool regmap_printable(struct regmap *map, unsigned int reg)
81 {
82 	if (regmap_precious(map, reg))
83 		return false;
84 
85 	if (!regmap_readable(map, reg) && !regmap_cached(map, reg))
86 		return false;
87 
88 	return true;
89 }
90 
91 /*
92  * Work out where the start offset maps into register numbers, bearing
93  * in mind that we suppress hidden registers.
94  */
95 static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
96 						  unsigned int base,
97 						  loff_t from,
98 						  loff_t *pos)
99 {
100 	struct regmap_debugfs_off_cache *c = NULL;
101 	loff_t p = 0;
102 	unsigned int i, ret;
103 	unsigned int fpos_offset;
104 	unsigned int reg_offset;
105 
106 	/* Suppress the cache if we're using a subrange */
107 	if (base)
108 		return base;
109 
110 	/*
111 	 * If we don't have a cache build one so we don't have to do a
112 	 * linear scan each time.
113 	 */
114 	mutex_lock(&map->cache_lock);
115 	i = base;
116 	if (list_empty(&map->debugfs_off_cache)) {
117 		for (; i <= map->max_register; i += map->reg_stride) {
118 			/* Skip unprinted registers, closing off cache entry */
119 			if (!regmap_printable(map, i)) {
120 				if (c) {
121 					c->max = p - 1;
122 					c->max_reg = i - map->reg_stride;
123 					list_add_tail(&c->list,
124 						      &map->debugfs_off_cache);
125 					c = NULL;
126 				}
127 
128 				continue;
129 			}
130 
131 			/* No cache entry?  Start a new one */
132 			if (!c) {
133 				c = kzalloc(sizeof(*c), GFP_KERNEL);
134 				if (!c) {
135 					regmap_debugfs_free_dump_cache(map);
136 					mutex_unlock(&map->cache_lock);
137 					return base;
138 				}
139 				c->min = p;
140 				c->base_reg = i;
141 			}
142 
143 			p += map->debugfs_tot_len;
144 		}
145 	}
146 
147 	/* Close the last entry off if we didn't scan beyond it */
148 	if (c) {
149 		c->max = p - 1;
150 		c->max_reg = i - map->reg_stride;
151 		list_add_tail(&c->list,
152 			      &map->debugfs_off_cache);
153 	}
154 
155 	/*
156 	 * This should never happen; we return above if we fail to
157 	 * allocate and we should never be in this code if there are
158 	 * no registers at all.
159 	 */
160 	WARN_ON(list_empty(&map->debugfs_off_cache));
161 	ret = base;
162 
163 	/* Find the relevant block:offset */
164 	list_for_each_entry(c, &map->debugfs_off_cache, list) {
165 		if (from >= c->min && from <= c->max) {
166 			fpos_offset = from - c->min;
167 			reg_offset = fpos_offset / map->debugfs_tot_len;
168 			*pos = c->min + (reg_offset * map->debugfs_tot_len);
169 			mutex_unlock(&map->cache_lock);
170 			return c->base_reg + (reg_offset * map->reg_stride);
171 		}
172 
173 		*pos = c->max;
174 		ret = c->max_reg;
175 	}
176 	mutex_unlock(&map->cache_lock);
177 
178 	return ret;
179 }
180 
181 static inline void regmap_calc_tot_len(struct regmap *map,
182 				       void *buf, size_t count)
183 {
184 	/* Calculate the length of a fixed format  */
185 	if (!map->debugfs_tot_len) {
186 		map->debugfs_reg_len = regmap_calc_reg_len(map->max_register);
187 		map->debugfs_val_len = 2 * map->format.val_bytes;
188 		map->debugfs_tot_len = map->debugfs_reg_len +
189 			map->debugfs_val_len + 3;      /* : \n */
190 	}
191 }
192 
193 static int regmap_next_readable_reg(struct regmap *map, int reg)
194 {
195 	struct regmap_debugfs_off_cache *c;
196 	int ret = -EINVAL;
197 
198 	if (regmap_printable(map, reg + map->reg_stride)) {
199 		ret = reg + map->reg_stride;
200 	} else {
201 		mutex_lock(&map->cache_lock);
202 		list_for_each_entry(c, &map->debugfs_off_cache, list) {
203 			if (reg > c->max_reg)
204 				continue;
205 			if (reg < c->base_reg) {
206 				ret = c->base_reg;
207 				break;
208 			}
209 		}
210 		mutex_unlock(&map->cache_lock);
211 	}
212 	return ret;
213 }
214 
215 static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
216 				   unsigned int to, char __user *user_buf,
217 				   size_t count, loff_t *ppos)
218 {
219 	size_t buf_pos = 0;
220 	loff_t p = *ppos;
221 	ssize_t ret;
222 	int i;
223 	char *buf;
224 	unsigned int val, start_reg;
225 
226 	if (*ppos < 0 || !count)
227 		return -EINVAL;
228 
229 	if (count > (PAGE_SIZE << MAX_ORDER))
230 		count = PAGE_SIZE << MAX_ORDER;
231 
232 	buf = kmalloc(count, GFP_KERNEL);
233 	if (!buf)
234 		return -ENOMEM;
235 
236 	regmap_calc_tot_len(map, buf, count);
237 
238 	/* Work out which register we're starting at */
239 	start_reg = regmap_debugfs_get_dump_start(map, from, *ppos, &p);
240 
241 	for (i = start_reg; i >= 0 && i <= to;
242 	     i = regmap_next_readable_reg(map, i)) {
243 
244 		/* If we're in the region the user is trying to read */
245 		if (p >= *ppos) {
246 			/* ...but not beyond it */
247 			if (buf_pos + map->debugfs_tot_len > count)
248 				break;
249 
250 			/* Format the register */
251 			snprintf(buf + buf_pos, count - buf_pos, "%.*x: ",
252 				 map->debugfs_reg_len, i - from);
253 			buf_pos += map->debugfs_reg_len + 2;
254 
255 			/* Format the value, write all X if we can't read */
256 			ret = regmap_read(map, i, &val);
257 			if (ret == 0)
258 				snprintf(buf + buf_pos, count - buf_pos,
259 					 "%.*x", map->debugfs_val_len, val);
260 			else
261 				memset(buf + buf_pos, 'X',
262 				       map->debugfs_val_len);
263 			buf_pos += 2 * map->format.val_bytes;
264 
265 			buf[buf_pos++] = '\n';
266 		}
267 		p += map->debugfs_tot_len;
268 	}
269 
270 	ret = buf_pos;
271 
272 	if (copy_to_user(user_buf, buf, buf_pos)) {
273 		ret = -EFAULT;
274 		goto out;
275 	}
276 
277 	*ppos += buf_pos;
278 
279 out:
280 	kfree(buf);
281 	return ret;
282 }
283 
284 static ssize_t regmap_map_read_file(struct file *file, char __user *user_buf,
285 				    size_t count, loff_t *ppos)
286 {
287 	struct regmap *map = file->private_data;
288 
289 	return regmap_read_debugfs(map, 0, map->max_register, user_buf,
290 				   count, ppos);
291 }
292 
293 #undef REGMAP_ALLOW_WRITE_DEBUGFS
294 #ifdef REGMAP_ALLOW_WRITE_DEBUGFS
295 /*
296  * This can be dangerous especially when we have clients such as
297  * PMICs, therefore don't provide any real compile time configuration option
298  * for this feature, people who want to use this will need to modify
299  * the source code directly.
300  */
301 static ssize_t regmap_map_write_file(struct file *file,
302 				     const char __user *user_buf,
303 				     size_t count, loff_t *ppos)
304 {
305 	char buf[32];
306 	size_t buf_size;
307 	char *start = buf;
308 	unsigned long reg, value;
309 	struct regmap *map = file->private_data;
310 	int ret;
311 
312 	buf_size = min(count, (sizeof(buf)-1));
313 	if (copy_from_user(buf, user_buf, buf_size))
314 		return -EFAULT;
315 	buf[buf_size] = 0;
316 
317 	while (*start == ' ')
318 		start++;
319 	reg = simple_strtoul(start, &start, 16);
320 	while (*start == ' ')
321 		start++;
322 	if (kstrtoul(start, 16, &value))
323 		return -EINVAL;
324 
325 	/* Userspace has been fiddling around behind the kernel's back */
326 	add_taint(TAINT_USER, LOCKDEP_STILL_OK);
327 
328 	ret = regmap_write(map, reg, value);
329 	if (ret < 0)
330 		return ret;
331 	return buf_size;
332 }
333 #else
334 #define regmap_map_write_file NULL
335 #endif
336 
337 static const struct file_operations regmap_map_fops = {
338 	.open = simple_open,
339 	.read = regmap_map_read_file,
340 	.write = regmap_map_write_file,
341 	.llseek = default_llseek,
342 };
343 
344 static ssize_t regmap_range_read_file(struct file *file, char __user *user_buf,
345 				      size_t count, loff_t *ppos)
346 {
347 	struct regmap_range_node *range = file->private_data;
348 	struct regmap *map = range->map;
349 
350 	return regmap_read_debugfs(map, range->range_min, range->range_max,
351 				   user_buf, count, ppos);
352 }
353 
354 static const struct file_operations regmap_range_fops = {
355 	.open = simple_open,
356 	.read = regmap_range_read_file,
357 	.llseek = default_llseek,
358 };
359 
360 static ssize_t regmap_reg_ranges_read_file(struct file *file,
361 					   char __user *user_buf, size_t count,
362 					   loff_t *ppos)
363 {
364 	struct regmap *map = file->private_data;
365 	struct regmap_debugfs_off_cache *c;
366 	loff_t p = 0;
367 	size_t buf_pos = 0;
368 	char *buf;
369 	char *entry;
370 	int ret;
371 	unsigned int entry_len;
372 
373 	if (*ppos < 0 || !count)
374 		return -EINVAL;
375 
376 	if (count > (PAGE_SIZE << MAX_ORDER))
377 		count = PAGE_SIZE << MAX_ORDER;
378 
379 	buf = kmalloc(count, GFP_KERNEL);
380 	if (!buf)
381 		return -ENOMEM;
382 
383 	entry = kmalloc(PAGE_SIZE, GFP_KERNEL);
384 	if (!entry) {
385 		kfree(buf);
386 		return -ENOMEM;
387 	}
388 
389 	/* While we are at it, build the register dump cache
390 	 * now so the read() operation on the `registers' file
391 	 * can benefit from using the cache.  We do not care
392 	 * about the file position information that is contained
393 	 * in the cache, just about the actual register blocks */
394 	regmap_calc_tot_len(map, buf, count);
395 	regmap_debugfs_get_dump_start(map, 0, *ppos, &p);
396 
397 	/* Reset file pointer as the fixed-format of the `registers'
398 	 * file is not compatible with the `range' file */
399 	p = 0;
400 	mutex_lock(&map->cache_lock);
401 	list_for_each_entry(c, &map->debugfs_off_cache, list) {
402 		entry_len = snprintf(entry, PAGE_SIZE, "%x-%x\n",
403 				     c->base_reg, c->max_reg);
404 		if (p >= *ppos) {
405 			if (buf_pos + entry_len > count)
406 				break;
407 			memcpy(buf + buf_pos, entry, entry_len);
408 			buf_pos += entry_len;
409 		}
410 		p += entry_len;
411 	}
412 	mutex_unlock(&map->cache_lock);
413 
414 	kfree(entry);
415 	ret = buf_pos;
416 
417 	if (copy_to_user(user_buf, buf, buf_pos)) {
418 		ret = -EFAULT;
419 		goto out_buf;
420 	}
421 
422 	*ppos += buf_pos;
423 out_buf:
424 	kfree(buf);
425 	return ret;
426 }
427 
428 static const struct file_operations regmap_reg_ranges_fops = {
429 	.open = simple_open,
430 	.read = regmap_reg_ranges_read_file,
431 	.llseek = default_llseek,
432 };
433 
434 static int regmap_access_show(struct seq_file *s, void *ignored)
435 {
436 	struct regmap *map = s->private;
437 	int i, reg_len;
438 
439 	reg_len = regmap_calc_reg_len(map->max_register);
440 
441 	for (i = 0; i <= map->max_register; i += map->reg_stride) {
442 		/* Ignore registers which are neither readable nor writable */
443 		if (!regmap_readable(map, i) && !regmap_writeable(map, i))
444 			continue;
445 
446 		/* Format the register */
447 		seq_printf(s, "%.*x: %c %c %c %c\n", reg_len, i,
448 			   regmap_readable(map, i) ? 'y' : 'n',
449 			   regmap_writeable(map, i) ? 'y' : 'n',
450 			   regmap_volatile(map, i) ? 'y' : 'n',
451 			   regmap_precious(map, i) ? 'y' : 'n');
452 	}
453 
454 	return 0;
455 }
456 
457 DEFINE_SHOW_ATTRIBUTE(regmap_access);
458 
459 static ssize_t regmap_cache_only_write_file(struct file *file,
460 					    const char __user *user_buf,
461 					    size_t count, loff_t *ppos)
462 {
463 	struct regmap *map = container_of(file->private_data,
464 					  struct regmap, cache_only);
465 	bool new_val, require_sync = false;
466 	int err;
467 
468 	err = kstrtobool_from_user(user_buf, count, &new_val);
469 	/* Ignore malforned data like debugfs_write_file_bool() */
470 	if (err)
471 		return count;
472 
473 	err = debugfs_file_get(file->f_path.dentry);
474 	if (err)
475 		return err;
476 
477 	map->lock(map->lock_arg);
478 
479 	if (new_val && !map->cache_only) {
480 		dev_warn(map->dev, "debugfs cache_only=Y forced\n");
481 		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
482 	} else if (!new_val && map->cache_only) {
483 		dev_warn(map->dev, "debugfs cache_only=N forced: syncing cache\n");
484 		require_sync = true;
485 	}
486 	map->cache_only = new_val;
487 
488 	map->unlock(map->lock_arg);
489 	debugfs_file_put(file->f_path.dentry);
490 
491 	if (require_sync) {
492 		err = regcache_sync(map);
493 		if (err)
494 			dev_err(map->dev, "Failed to sync cache %d\n", err);
495 	}
496 
497 	return count;
498 }
499 
500 static const struct file_operations regmap_cache_only_fops = {
501 	.open = simple_open,
502 	.read = debugfs_read_file_bool,
503 	.write = regmap_cache_only_write_file,
504 };
505 
506 static ssize_t regmap_cache_bypass_write_file(struct file *file,
507 					      const char __user *user_buf,
508 					      size_t count, loff_t *ppos)
509 {
510 	struct regmap *map = container_of(file->private_data,
511 					  struct regmap, cache_bypass);
512 	bool new_val;
513 	int err;
514 
515 	err = kstrtobool_from_user(user_buf, count, &new_val);
516 	/* Ignore malforned data like debugfs_write_file_bool() */
517 	if (err)
518 		return count;
519 
520 	err = debugfs_file_get(file->f_path.dentry);
521 	if (err)
522 		return err;
523 
524 	map->lock(map->lock_arg);
525 
526 	if (new_val && !map->cache_bypass) {
527 		dev_warn(map->dev, "debugfs cache_bypass=Y forced\n");
528 		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
529 	} else if (!new_val && map->cache_bypass) {
530 		dev_warn(map->dev, "debugfs cache_bypass=N forced\n");
531 	}
532 	map->cache_bypass = new_val;
533 
534 	map->unlock(map->lock_arg);
535 	debugfs_file_put(file->f_path.dentry);
536 
537 	return count;
538 }
539 
540 static const struct file_operations regmap_cache_bypass_fops = {
541 	.open = simple_open,
542 	.read = debugfs_read_file_bool,
543 	.write = regmap_cache_bypass_write_file,
544 };
545 
546 void regmap_debugfs_init(struct regmap *map)
547 {
548 	struct rb_node *next;
549 	struct regmap_range_node *range_node;
550 	const char *devname = "dummy";
551 	const char *name = map->name;
552 
553 	/*
554 	 * Userspace can initiate reads from the hardware over debugfs.
555 	 * Normally internal regmap structures and buffers are protected with
556 	 * a mutex or a spinlock, but if the regmap owner decided to disable
557 	 * all locking mechanisms, this is no longer the case. For safety:
558 	 * don't create the debugfs entries if locking is disabled.
559 	 */
560 	if (map->debugfs_disable) {
561 		dev_dbg(map->dev, "regmap locking disabled - not creating debugfs entries\n");
562 		return;
563 	}
564 
565 	/* If we don't have the debugfs root yet, postpone init */
566 	if (!regmap_debugfs_root) {
567 		struct regmap_debugfs_node *node;
568 		node = kzalloc(sizeof(*node), GFP_KERNEL);
569 		if (!node)
570 			return;
571 		node->map = map;
572 		mutex_lock(&regmap_debugfs_early_lock);
573 		list_add(&node->link, &regmap_debugfs_early_list);
574 		mutex_unlock(&regmap_debugfs_early_lock);
575 		return;
576 	}
577 
578 	INIT_LIST_HEAD(&map->debugfs_off_cache);
579 	mutex_init(&map->cache_lock);
580 
581 	if (map->dev)
582 		devname = dev_name(map->dev);
583 
584 	if (name) {
585 		if (!map->debugfs_name) {
586 			map->debugfs_name = kasprintf(GFP_KERNEL, "%s-%s",
587 					      devname, name);
588 			if (!map->debugfs_name)
589 				return;
590 		}
591 		name = map->debugfs_name;
592 	} else {
593 		name = devname;
594 	}
595 
596 	if (!strcmp(name, "dummy")) {
597 		kfree(map->debugfs_name);
598 		map->debugfs_name = kasprintf(GFP_KERNEL, "dummy%d",
599 						dummy_index);
600 		if (!map->debugfs_name)
601 			return;
602 		name = map->debugfs_name;
603 		dummy_index++;
604 	}
605 
606 	map->debugfs = debugfs_create_dir(name, regmap_debugfs_root);
607 
608 	debugfs_create_file("name", 0400, map->debugfs,
609 			    map, &regmap_name_fops);
610 
611 	debugfs_create_file("range", 0400, map->debugfs,
612 			    map, &regmap_reg_ranges_fops);
613 
614 	if (map->max_register || regmap_readable(map, 0)) {
615 		umode_t registers_mode;
616 
617 #if defined(REGMAP_ALLOW_WRITE_DEBUGFS)
618 		registers_mode = 0600;
619 #else
620 		registers_mode = 0400;
621 #endif
622 
623 		debugfs_create_file("registers", registers_mode, map->debugfs,
624 				    map, &regmap_map_fops);
625 		debugfs_create_file("access", 0400, map->debugfs,
626 				    map, &regmap_access_fops);
627 	}
628 
629 	if (map->cache_type) {
630 		debugfs_create_file("cache_only", 0600, map->debugfs,
631 				    &map->cache_only, &regmap_cache_only_fops);
632 		debugfs_create_bool("cache_dirty", 0400, map->debugfs,
633 				    &map->cache_dirty);
634 		debugfs_create_file("cache_bypass", 0600, map->debugfs,
635 				    &map->cache_bypass,
636 				    &regmap_cache_bypass_fops);
637 	}
638 
639 	/*
640 	 * This could interfere with driver operation. Therefore, don't provide
641 	 * any real compile time configuration option for this feature. One will
642 	 * have to modify the source code directly in order to use it.
643 	 */
644 #undef REGMAP_ALLOW_FORCE_WRITE_FIELD_DEBUGFS
645 #ifdef REGMAP_ALLOW_FORCE_WRITE_FIELD_DEBUGFS
646 	debugfs_create_bool("force_write_field", 0600, map->debugfs,
647 			    &map->force_write_field);
648 #endif
649 
650 	next = rb_first(&map->range_tree);
651 	while (next) {
652 		range_node = rb_entry(next, struct regmap_range_node, node);
653 
654 		if (range_node->name)
655 			debugfs_create_file(range_node->name, 0400,
656 					    map->debugfs, range_node,
657 					    &regmap_range_fops);
658 
659 		next = rb_next(&range_node->node);
660 	}
661 
662 	if (map->cache_ops && map->cache_ops->debugfs_init)
663 		map->cache_ops->debugfs_init(map);
664 }
665 
666 void regmap_debugfs_exit(struct regmap *map)
667 {
668 	if (map->debugfs) {
669 		debugfs_remove_recursive(map->debugfs);
670 		mutex_lock(&map->cache_lock);
671 		regmap_debugfs_free_dump_cache(map);
672 		mutex_unlock(&map->cache_lock);
673 		kfree(map->debugfs_name);
674 		map->debugfs_name = NULL;
675 	} else {
676 		struct regmap_debugfs_node *node, *tmp;
677 
678 		mutex_lock(&regmap_debugfs_early_lock);
679 		list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list,
680 					 link) {
681 			if (node->map == map) {
682 				list_del(&node->link);
683 				kfree(node);
684 			}
685 		}
686 		mutex_unlock(&regmap_debugfs_early_lock);
687 	}
688 }
689 
690 void regmap_debugfs_initcall(void)
691 {
692 	struct regmap_debugfs_node *node, *tmp;
693 
694 	regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
695 
696 	mutex_lock(&regmap_debugfs_early_lock);
697 	list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list, link) {
698 		regmap_debugfs_init(node->map);
699 		list_del(&node->link);
700 		kfree(node);
701 	}
702 	mutex_unlock(&regmap_debugfs_early_lock);
703 }
704