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 
85 	/*
86 	 * If we don't have a cache build one so we don't have to do a
87 	 * linear scan each time.
88 	 */
89 	if (list_empty(&map->debugfs_off_cache)) {
90 		for (i = base; i <= map->max_register; i += map->reg_stride) {
91 			/* Skip unprinted registers, closing off cache entry */
92 			if (!regmap_readable(map, i) ||
93 			    regmap_precious(map, i)) {
94 				if (c) {
95 					c->max = p - 1;
96 					list_add_tail(&c->list,
97 						      &map->debugfs_off_cache);
98 					c = NULL;
99 				}
100 
101 				continue;
102 			}
103 
104 			/* No cache entry?  Start a new one */
105 			if (!c) {
106 				c = kzalloc(sizeof(*c), GFP_KERNEL);
107 				if (!c) {
108 					regmap_debugfs_free_dump_cache(map);
109 					return base;
110 				}
111 				c->min = p;
112 				c->base_reg = i;
113 			}
114 
115 			p += map->debugfs_tot_len;
116 		}
117 	}
118 
119 	/* Close the last entry off if we didn't scan beyond it */
120 	if (c) {
121 		c->max = p - 1;
122 		list_add_tail(&c->list,
123 			      &map->debugfs_off_cache);
124 	}
125 
126 	/*
127 	 * This should never happen; we return above if we fail to
128 	 * allocate and we should never be in this code if there are
129 	 * no registers at all.
130 	 */
131 	if (list_empty(&map->debugfs_off_cache)) {
132 		WARN_ON(list_empty(&map->debugfs_off_cache));
133 		return base;
134 	}
135 
136 	/* Find the relevant block */
137 	list_for_each_entry(c, &map->debugfs_off_cache, list) {
138 		if (from >= c->min && from <= c->max) {
139 			*pos = c->min;
140 			return c->base_reg;
141 		}
142 
143 		*pos = c->min;
144 		ret = c->base_reg;
145 	}
146 
147 	return ret;
148 }
149 
150 static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
151 				   unsigned int to, char __user *user_buf,
152 				   size_t count, loff_t *ppos)
153 {
154 	size_t buf_pos = 0;
155 	loff_t p = *ppos;
156 	ssize_t ret;
157 	int i;
158 	char *buf;
159 	unsigned int val, start_reg;
160 
161 	if (*ppos < 0 || !count)
162 		return -EINVAL;
163 
164 	buf = kmalloc(count, GFP_KERNEL);
165 	if (!buf)
166 		return -ENOMEM;
167 
168 	/* Calculate the length of a fixed format  */
169 	if (!map->debugfs_tot_len) {
170 		map->debugfs_reg_len = regmap_calc_reg_len(map->max_register,
171 							   buf, count);
172 		map->debugfs_val_len = 2 * map->format.val_bytes;
173 		map->debugfs_tot_len = map->debugfs_reg_len +
174 			map->debugfs_val_len + 3;      /* : \n */
175 	}
176 
177 	/* Work out which register we're starting at */
178 	start_reg = regmap_debugfs_get_dump_start(map, from, *ppos, &p);
179 
180 	for (i = start_reg; i <= to; i += map->reg_stride) {
181 		if (!regmap_readable(map, i))
182 			continue;
183 
184 		if (regmap_precious(map, i))
185 			continue;
186 
187 		/* If we're in the region the user is trying to read */
188 		if (p >= *ppos) {
189 			/* ...but not beyond it */
190 			if (buf_pos + 1 + map->debugfs_tot_len >= count)
191 				break;
192 
193 			/* Format the register */
194 			snprintf(buf + buf_pos, count - buf_pos, "%.*x: ",
195 				 map->debugfs_reg_len, i - from);
196 			buf_pos += map->debugfs_reg_len + 2;
197 
198 			/* Format the value, write all X if we can't read */
199 			ret = regmap_read(map, i, &val);
200 			if (ret == 0)
201 				snprintf(buf + buf_pos, count - buf_pos,
202 					 "%.*x", map->debugfs_val_len, val);
203 			else
204 				memset(buf + buf_pos, 'X',
205 				       map->debugfs_val_len);
206 			buf_pos += 2 * map->format.val_bytes;
207 
208 			buf[buf_pos++] = '\n';
209 		}
210 		p += map->debugfs_tot_len;
211 	}
212 
213 	ret = buf_pos;
214 
215 	if (copy_to_user(user_buf, buf, buf_pos)) {
216 		ret = -EFAULT;
217 		goto out;
218 	}
219 
220 	*ppos += buf_pos;
221 
222 out:
223 	kfree(buf);
224 	return ret;
225 }
226 
227 static ssize_t regmap_map_read_file(struct file *file, char __user *user_buf,
228 				    size_t count, loff_t *ppos)
229 {
230 	struct regmap *map = file->private_data;
231 
232 	return regmap_read_debugfs(map, 0, map->max_register, user_buf,
233 				   count, ppos);
234 }
235 
236 #undef REGMAP_ALLOW_WRITE_DEBUGFS
237 #ifdef REGMAP_ALLOW_WRITE_DEBUGFS
238 /*
239  * This can be dangerous especially when we have clients such as
240  * PMICs, therefore don't provide any real compile time configuration option
241  * for this feature, people who want to use this will need to modify
242  * the source code directly.
243  */
244 static ssize_t regmap_map_write_file(struct file *file,
245 				     const char __user *user_buf,
246 				     size_t count, loff_t *ppos)
247 {
248 	char buf[32];
249 	size_t buf_size;
250 	char *start = buf;
251 	unsigned long reg, value;
252 	struct regmap *map = file->private_data;
253 
254 	buf_size = min(count, (sizeof(buf)-1));
255 	if (copy_from_user(buf, user_buf, buf_size))
256 		return -EFAULT;
257 	buf[buf_size] = 0;
258 
259 	while (*start == ' ')
260 		start++;
261 	reg = simple_strtoul(start, &start, 16);
262 	while (*start == ' ')
263 		start++;
264 	if (strict_strtoul(start, 16, &value))
265 		return -EINVAL;
266 
267 	/* Userspace has been fiddling around behind the kernel's back */
268 	add_taint(TAINT_USER);
269 
270 	regmap_write(map, reg, value);
271 	return buf_size;
272 }
273 #else
274 #define regmap_map_write_file NULL
275 #endif
276 
277 static const struct file_operations regmap_map_fops = {
278 	.open = simple_open,
279 	.read = regmap_map_read_file,
280 	.write = regmap_map_write_file,
281 	.llseek = default_llseek,
282 };
283 
284 static ssize_t regmap_range_read_file(struct file *file, char __user *user_buf,
285 				      size_t count, loff_t *ppos)
286 {
287 	struct regmap_range_node *range = file->private_data;
288 	struct regmap *map = range->map;
289 
290 	return regmap_read_debugfs(map, range->range_min, range->range_max,
291 				   user_buf, count, ppos);
292 }
293 
294 static const struct file_operations regmap_range_fops = {
295 	.open = simple_open,
296 	.read = regmap_range_read_file,
297 	.llseek = default_llseek,
298 };
299 
300 static ssize_t regmap_access_read_file(struct file *file,
301 				       char __user *user_buf, size_t count,
302 				       loff_t *ppos)
303 {
304 	int reg_len, tot_len;
305 	size_t buf_pos = 0;
306 	loff_t p = 0;
307 	ssize_t ret;
308 	int i;
309 	struct regmap *map = file->private_data;
310 	char *buf;
311 
312 	if (*ppos < 0 || !count)
313 		return -EINVAL;
314 
315 	buf = kmalloc(count, GFP_KERNEL);
316 	if (!buf)
317 		return -ENOMEM;
318 
319 	/* Calculate the length of a fixed format  */
320 	reg_len = regmap_calc_reg_len(map->max_register, buf, count);
321 	tot_len = reg_len + 10; /* ': R W V P\n' */
322 
323 	for (i = 0; i <= map->max_register; i += map->reg_stride) {
324 		/* Ignore registers which are neither readable nor writable */
325 		if (!regmap_readable(map, i) && !regmap_writeable(map, i))
326 			continue;
327 
328 		/* If we're in the region the user is trying to read */
329 		if (p >= *ppos) {
330 			/* ...but not beyond it */
331 			if (buf_pos >= count - 1 - tot_len)
332 				break;
333 
334 			/* Format the register */
335 			snprintf(buf + buf_pos, count - buf_pos,
336 				 "%.*x: %c %c %c %c\n",
337 				 reg_len, i,
338 				 regmap_readable(map, i) ? 'y' : 'n',
339 				 regmap_writeable(map, i) ? 'y' : 'n',
340 				 regmap_volatile(map, i) ? 'y' : 'n',
341 				 regmap_precious(map, i) ? 'y' : 'n');
342 
343 			buf_pos += tot_len;
344 		}
345 		p += tot_len;
346 	}
347 
348 	ret = buf_pos;
349 
350 	if (copy_to_user(user_buf, buf, buf_pos)) {
351 		ret = -EFAULT;
352 		goto out;
353 	}
354 
355 	*ppos += buf_pos;
356 
357 out:
358 	kfree(buf);
359 	return ret;
360 }
361 
362 static const struct file_operations regmap_access_fops = {
363 	.open = simple_open,
364 	.read = regmap_access_read_file,
365 	.llseek = default_llseek,
366 };
367 
368 void regmap_debugfs_init(struct regmap *map, const char *name)
369 {
370 	struct rb_node *next;
371 	struct regmap_range_node *range_node;
372 
373 	INIT_LIST_HEAD(&map->debugfs_off_cache);
374 
375 	if (name) {
376 		map->debugfs_name = kasprintf(GFP_KERNEL, "%s-%s",
377 					      dev_name(map->dev), name);
378 		name = map->debugfs_name;
379 	} else {
380 		name = dev_name(map->dev);
381 	}
382 
383 	map->debugfs = debugfs_create_dir(name, regmap_debugfs_root);
384 	if (!map->debugfs) {
385 		dev_warn(map->dev, "Failed to create debugfs directory\n");
386 		return;
387 	}
388 
389 	debugfs_create_file("name", 0400, map->debugfs,
390 			    map, &regmap_name_fops);
391 
392 	if (map->max_register) {
393 		debugfs_create_file("registers", 0400, map->debugfs,
394 				    map, &regmap_map_fops);
395 		debugfs_create_file("access", 0400, map->debugfs,
396 				    map, &regmap_access_fops);
397 	}
398 
399 	if (map->cache_type) {
400 		debugfs_create_bool("cache_only", 0400, map->debugfs,
401 				    &map->cache_only);
402 		debugfs_create_bool("cache_dirty", 0400, map->debugfs,
403 				    &map->cache_dirty);
404 		debugfs_create_bool("cache_bypass", 0400, map->debugfs,
405 				    &map->cache_bypass);
406 	}
407 
408 	next = rb_first(&map->range_tree);
409 	while (next) {
410 		range_node = rb_entry(next, struct regmap_range_node, node);
411 
412 		if (range_node->name)
413 			debugfs_create_file(range_node->name, 0400,
414 					    map->debugfs, range_node,
415 					    &regmap_range_fops);
416 
417 		next = rb_next(&range_node->node);
418 	}
419 }
420 
421 void regmap_debugfs_exit(struct regmap *map)
422 {
423 	debugfs_remove_recursive(map->debugfs);
424 	regmap_debugfs_free_dump_cache(map);
425 	kfree(map->debugfs_name);
426 }
427 
428 void regmap_debugfs_initcall(void)
429 {
430 	regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
431 	if (!regmap_debugfs_root) {
432 		pr_warn("regmap: Failed to create debugfs root\n");
433 		return;
434 	}
435 }
436