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 
19 #include "internal.h"
20 
21 static struct dentry *regmap_debugfs_root;
22 
23 /* Calculate the length of a fixed format  */
24 static size_t regmap_calc_reg_len(int max_val, char *buf, size_t buf_size)
25 {
26 	snprintf(buf, buf_size, "%x", max_val);
27 	return strlen(buf);
28 }
29 
30 static ssize_t regmap_name_read_file(struct file *file,
31 				     char __user *user_buf, size_t count,
32 				     loff_t *ppos)
33 {
34 	struct regmap *map = file->private_data;
35 	int ret;
36 	char *buf;
37 
38 	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
39 	if (!buf)
40 		return -ENOMEM;
41 
42 	ret = snprintf(buf, PAGE_SIZE, "%s\n", map->dev->driver->name);
43 	if (ret < 0) {
44 		kfree(buf);
45 		return ret;
46 	}
47 
48 	ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
49 	kfree(buf);
50 	return ret;
51 }
52 
53 static const struct file_operations regmap_name_fops = {
54 	.open = simple_open,
55 	.read = regmap_name_read_file,
56 	.llseek = default_llseek,
57 };
58 
59 static void regmap_debugfs_free_dump_cache(struct regmap *map)
60 {
61 	struct regmap_debugfs_off_cache *c;
62 
63 	while (!list_empty(&map->debugfs_off_cache)) {
64 		c = list_first_entry(&map->debugfs_off_cache,
65 				     struct regmap_debugfs_off_cache,
66 				     list);
67 		list_del(&c->list);
68 		kfree(c);
69 	}
70 }
71 
72 /*
73  * Work out where the start offset maps into register numbers, bearing
74  * in mind that we suppress hidden registers.
75  */
76 static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
77 						  unsigned int base,
78 						  loff_t from,
79 						  loff_t *pos)
80 {
81 	struct regmap_debugfs_off_cache *c = NULL;
82 	loff_t p = 0;
83 	unsigned int i, ret;
84 	unsigned int fpos_offset;
85 	unsigned int reg_offset;
86 
87 	/* Suppress the cache if we're using a subrange */
88 	if (base)
89 		return base;
90 
91 	/*
92 	 * If we don't have a cache build one so we don't have to do a
93 	 * linear scan each time.
94 	 */
95 	mutex_lock(&map->cache_lock);
96 	i = base;
97 	if (list_empty(&map->debugfs_off_cache)) {
98 		for (; i <= map->max_register; i += map->reg_stride) {
99 			/* Skip unprinted registers, closing off cache entry */
100 			if (!regmap_readable(map, i) ||
101 			    regmap_precious(map, i)) {
102 				if (c) {
103 					c->max = p - 1;
104 					c->max_reg = i - map->reg_stride;
105 					list_add_tail(&c->list,
106 						      &map->debugfs_off_cache);
107 					c = NULL;
108 				}
109 
110 				continue;
111 			}
112 
113 			/* No cache entry?  Start a new one */
114 			if (!c) {
115 				c = kzalloc(sizeof(*c), GFP_KERNEL);
116 				if (!c) {
117 					regmap_debugfs_free_dump_cache(map);
118 					mutex_unlock(&map->cache_lock);
119 					return base;
120 				}
121 				c->min = p;
122 				c->base_reg = i;
123 			}
124 
125 			p += map->debugfs_tot_len;
126 		}
127 	}
128 
129 	/* Close the last entry off if we didn't scan beyond it */
130 	if (c) {
131 		c->max = p - 1;
132 		c->max_reg = i - map->reg_stride;
133 		list_add_tail(&c->list,
134 			      &map->debugfs_off_cache);
135 	}
136 
137 	/*
138 	 * This should never happen; we return above if we fail to
139 	 * allocate and we should never be in this code if there are
140 	 * no registers at all.
141 	 */
142 	WARN_ON(list_empty(&map->debugfs_off_cache));
143 	ret = base;
144 
145 	/* Find the relevant block:offset */
146 	list_for_each_entry(c, &map->debugfs_off_cache, list) {
147 		if (from >= c->min && from <= c->max) {
148 			fpos_offset = from - c->min;
149 			reg_offset = fpos_offset / map->debugfs_tot_len;
150 			*pos = c->min + (reg_offset * map->debugfs_tot_len);
151 			mutex_unlock(&map->cache_lock);
152 			return c->base_reg + (reg_offset * map->reg_stride);
153 		}
154 
155 		*pos = c->max;
156 		ret = c->max_reg;
157 	}
158 	mutex_unlock(&map->cache_lock);
159 
160 	return ret;
161 }
162 
163 static inline void regmap_calc_tot_len(struct regmap *map,
164 				       void *buf, size_t count)
165 {
166 	/* Calculate the length of a fixed format  */
167 	if (!map->debugfs_tot_len) {
168 		map->debugfs_reg_len = regmap_calc_reg_len(map->max_register,
169 							   buf, count);
170 		map->debugfs_val_len = 2 * map->format.val_bytes;
171 		map->debugfs_tot_len = map->debugfs_reg_len +
172 			map->debugfs_val_len + 3;      /* : \n */
173 	}
174 }
175 
176 static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
177 				   unsigned int to, char __user *user_buf,
178 				   size_t count, loff_t *ppos)
179 {
180 	size_t buf_pos = 0;
181 	loff_t p = *ppos;
182 	ssize_t ret;
183 	int i;
184 	char *buf;
185 	unsigned int val, start_reg;
186 
187 	if (*ppos < 0 || !count)
188 		return -EINVAL;
189 
190 	buf = kmalloc(count, GFP_KERNEL);
191 	if (!buf)
192 		return -ENOMEM;
193 
194 	regmap_calc_tot_len(map, buf, count);
195 
196 	/* Work out which register we're starting at */
197 	start_reg = regmap_debugfs_get_dump_start(map, from, *ppos, &p);
198 
199 	for (i = start_reg; i <= to; i += map->reg_stride) {
200 		if (!regmap_readable(map, i))
201 			continue;
202 
203 		if (regmap_precious(map, i))
204 			continue;
205 
206 		/* If we're in the region the user is trying to read */
207 		if (p >= *ppos) {
208 			/* ...but not beyond it */
209 			if (buf_pos + map->debugfs_tot_len > count)
210 				break;
211 
212 			/* Format the register */
213 			snprintf(buf + buf_pos, count - buf_pos, "%.*x: ",
214 				 map->debugfs_reg_len, i - from);
215 			buf_pos += map->debugfs_reg_len + 2;
216 
217 			/* Format the value, write all X if we can't read */
218 			ret = regmap_read(map, i, &val);
219 			if (ret == 0)
220 				snprintf(buf + buf_pos, count - buf_pos,
221 					 "%.*x", map->debugfs_val_len, val);
222 			else
223 				memset(buf + buf_pos, 'X',
224 				       map->debugfs_val_len);
225 			buf_pos += 2 * map->format.val_bytes;
226 
227 			buf[buf_pos++] = '\n';
228 		}
229 		p += map->debugfs_tot_len;
230 	}
231 
232 	ret = buf_pos;
233 
234 	if (copy_to_user(user_buf, buf, buf_pos)) {
235 		ret = -EFAULT;
236 		goto out;
237 	}
238 
239 	*ppos += buf_pos;
240 
241 out:
242 	kfree(buf);
243 	return ret;
244 }
245 
246 static ssize_t regmap_map_read_file(struct file *file, char __user *user_buf,
247 				    size_t count, loff_t *ppos)
248 {
249 	struct regmap *map = file->private_data;
250 
251 	return regmap_read_debugfs(map, 0, map->max_register, user_buf,
252 				   count, ppos);
253 }
254 
255 #undef REGMAP_ALLOW_WRITE_DEBUGFS
256 #ifdef REGMAP_ALLOW_WRITE_DEBUGFS
257 /*
258  * This can be dangerous especially when we have clients such as
259  * PMICs, therefore don't provide any real compile time configuration option
260  * for this feature, people who want to use this will need to modify
261  * the source code directly.
262  */
263 static ssize_t regmap_map_write_file(struct file *file,
264 				     const char __user *user_buf,
265 				     size_t count, loff_t *ppos)
266 {
267 	char buf[32];
268 	size_t buf_size;
269 	char *start = buf;
270 	unsigned long reg, value;
271 	struct regmap *map = file->private_data;
272 	int ret;
273 
274 	buf_size = min(count, (sizeof(buf)-1));
275 	if (copy_from_user(buf, user_buf, buf_size))
276 		return -EFAULT;
277 	buf[buf_size] = 0;
278 
279 	while (*start == ' ')
280 		start++;
281 	reg = simple_strtoul(start, &start, 16);
282 	while (*start == ' ')
283 		start++;
284 	if (kstrtoul(start, 16, &value))
285 		return -EINVAL;
286 
287 	/* Userspace has been fiddling around behind the kernel's back */
288 	add_taint(TAINT_USER, LOCKDEP_STILL_OK);
289 
290 	ret = regmap_write(map, reg, value);
291 	if (ret < 0)
292 		return ret;
293 	return buf_size;
294 }
295 #else
296 #define regmap_map_write_file NULL
297 #endif
298 
299 static const struct file_operations regmap_map_fops = {
300 	.open = simple_open,
301 	.read = regmap_map_read_file,
302 	.write = regmap_map_write_file,
303 	.llseek = default_llseek,
304 };
305 
306 static ssize_t regmap_range_read_file(struct file *file, char __user *user_buf,
307 				      size_t count, loff_t *ppos)
308 {
309 	struct regmap_range_node *range = file->private_data;
310 	struct regmap *map = range->map;
311 
312 	return regmap_read_debugfs(map, range->range_min, range->range_max,
313 				   user_buf, count, ppos);
314 }
315 
316 static const struct file_operations regmap_range_fops = {
317 	.open = simple_open,
318 	.read = regmap_range_read_file,
319 	.llseek = default_llseek,
320 };
321 
322 static ssize_t regmap_reg_ranges_read_file(struct file *file,
323 					   char __user *user_buf, size_t count,
324 					   loff_t *ppos)
325 {
326 	struct regmap *map = file->private_data;
327 	struct regmap_debugfs_off_cache *c;
328 	loff_t p = 0;
329 	size_t buf_pos = 0;
330 	char *buf;
331 	char *entry;
332 	int ret;
333 
334 	if (*ppos < 0 || !count)
335 		return -EINVAL;
336 
337 	buf = kmalloc(count, GFP_KERNEL);
338 	if (!buf)
339 		return -ENOMEM;
340 
341 	entry = kmalloc(PAGE_SIZE, GFP_KERNEL);
342 	if (!entry) {
343 		kfree(buf);
344 		return -ENOMEM;
345 	}
346 
347 	/* While we are at it, build the register dump cache
348 	 * now so the read() operation on the `registers' file
349 	 * can benefit from using the cache.  We do not care
350 	 * about the file position information that is contained
351 	 * in the cache, just about the actual register blocks */
352 	regmap_calc_tot_len(map, buf, count);
353 	regmap_debugfs_get_dump_start(map, 0, *ppos, &p);
354 
355 	/* Reset file pointer as the fixed-format of the `registers'
356 	 * file is not compatible with the `range' file */
357 	p = 0;
358 	mutex_lock(&map->cache_lock);
359 	list_for_each_entry(c, &map->debugfs_off_cache, list) {
360 		snprintf(entry, PAGE_SIZE, "%x-%x",
361 			 c->base_reg, c->max_reg);
362 		if (p >= *ppos) {
363 			if (buf_pos + 1 + strlen(entry) > count)
364 				break;
365 			snprintf(buf + buf_pos, count - buf_pos,
366 				 "%s", entry);
367 			buf_pos += strlen(entry);
368 			buf[buf_pos] = '\n';
369 			buf_pos++;
370 		}
371 		p += strlen(entry) + 1;
372 	}
373 	mutex_unlock(&map->cache_lock);
374 
375 	kfree(entry);
376 	ret = buf_pos;
377 
378 	if (copy_to_user(user_buf, buf, buf_pos)) {
379 		ret = -EFAULT;
380 		goto out_buf;
381 	}
382 
383 	*ppos += buf_pos;
384 out_buf:
385 	kfree(buf);
386 	return ret;
387 }
388 
389 static const struct file_operations regmap_reg_ranges_fops = {
390 	.open = simple_open,
391 	.read = regmap_reg_ranges_read_file,
392 	.llseek = default_llseek,
393 };
394 
395 static ssize_t regmap_access_read_file(struct file *file,
396 				       char __user *user_buf, size_t count,
397 				       loff_t *ppos)
398 {
399 	int reg_len, tot_len;
400 	size_t buf_pos = 0;
401 	loff_t p = 0;
402 	ssize_t ret;
403 	int i;
404 	struct regmap *map = file->private_data;
405 	char *buf;
406 
407 	if (*ppos < 0 || !count)
408 		return -EINVAL;
409 
410 	buf = kmalloc(count, GFP_KERNEL);
411 	if (!buf)
412 		return -ENOMEM;
413 
414 	/* Calculate the length of a fixed format  */
415 	reg_len = regmap_calc_reg_len(map->max_register, buf, count);
416 	tot_len = reg_len + 10; /* ': R W V P\n' */
417 
418 	for (i = 0; i <= map->max_register; i += map->reg_stride) {
419 		/* Ignore registers which are neither readable nor writable */
420 		if (!regmap_readable(map, i) && !regmap_writeable(map, i))
421 			continue;
422 
423 		/* If we're in the region the user is trying to read */
424 		if (p >= *ppos) {
425 			/* ...but not beyond it */
426 			if (buf_pos >= count - 1 - tot_len)
427 				break;
428 
429 			/* Format the register */
430 			snprintf(buf + buf_pos, count - buf_pos,
431 				 "%.*x: %c %c %c %c\n",
432 				 reg_len, i,
433 				 regmap_readable(map, i) ? 'y' : 'n',
434 				 regmap_writeable(map, i) ? 'y' : 'n',
435 				 regmap_volatile(map, i) ? 'y' : 'n',
436 				 regmap_precious(map, i) ? 'y' : 'n');
437 
438 			buf_pos += tot_len;
439 		}
440 		p += tot_len;
441 	}
442 
443 	ret = buf_pos;
444 
445 	if (copy_to_user(user_buf, buf, buf_pos)) {
446 		ret = -EFAULT;
447 		goto out;
448 	}
449 
450 	*ppos += buf_pos;
451 
452 out:
453 	kfree(buf);
454 	return ret;
455 }
456 
457 static const struct file_operations regmap_access_fops = {
458 	.open = simple_open,
459 	.read = regmap_access_read_file,
460 	.llseek = default_llseek,
461 };
462 
463 void regmap_debugfs_init(struct regmap *map, const char *name)
464 {
465 	struct rb_node *next;
466 	struct regmap_range_node *range_node;
467 
468 	INIT_LIST_HEAD(&map->debugfs_off_cache);
469 	mutex_init(&map->cache_lock);
470 
471 	if (name) {
472 		map->debugfs_name = kasprintf(GFP_KERNEL, "%s-%s",
473 					      dev_name(map->dev), name);
474 		name = map->debugfs_name;
475 	} else {
476 		name = dev_name(map->dev);
477 	}
478 
479 	map->debugfs = debugfs_create_dir(name, regmap_debugfs_root);
480 	if (!map->debugfs) {
481 		dev_warn(map->dev, "Failed to create debugfs directory\n");
482 		return;
483 	}
484 
485 	debugfs_create_file("name", 0400, map->debugfs,
486 			    map, &regmap_name_fops);
487 
488 	debugfs_create_file("range", 0400, map->debugfs,
489 			    map, &regmap_reg_ranges_fops);
490 
491 	if (map->max_register) {
492 		debugfs_create_file("registers", 0400, map->debugfs,
493 				    map, &regmap_map_fops);
494 		debugfs_create_file("access", 0400, map->debugfs,
495 				    map, &regmap_access_fops);
496 	}
497 
498 	if (map->cache_type) {
499 		debugfs_create_bool("cache_only", 0400, map->debugfs,
500 				    &map->cache_only);
501 		debugfs_create_bool("cache_dirty", 0400, map->debugfs,
502 				    &map->cache_dirty);
503 		debugfs_create_bool("cache_bypass", 0400, map->debugfs,
504 				    &map->cache_bypass);
505 	}
506 
507 	next = rb_first(&map->range_tree);
508 	while (next) {
509 		range_node = rb_entry(next, struct regmap_range_node, node);
510 
511 		if (range_node->name)
512 			debugfs_create_file(range_node->name, 0400,
513 					    map->debugfs, range_node,
514 					    &regmap_range_fops);
515 
516 		next = rb_next(&range_node->node);
517 	}
518 }
519 
520 void regmap_debugfs_exit(struct regmap *map)
521 {
522 	debugfs_remove_recursive(map->debugfs);
523 	mutex_lock(&map->cache_lock);
524 	regmap_debugfs_free_dump_cache(map);
525 	mutex_unlock(&map->cache_lock);
526 	kfree(map->debugfs_name);
527 }
528 
529 void regmap_debugfs_initcall(void)
530 {
531 	regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
532 	if (!regmap_debugfs_root) {
533 		pr_warn("regmap: Failed to create debugfs root\n");
534 		return;
535 	}
536 }
537