xref: /openbmc/linux/fs/debugfs/file.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  *  file.c - part of debugfs, a tiny little debug file system
3  *
4  *  Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
5  *  Copyright (C) 2004 IBM Inc.
6  *
7  *	This program is free software; you can redistribute it and/or
8  *	modify it under the terms of the GNU General Public License version
9  *	2 as published by the Free Software Foundation.
10  *
11  *  debugfs is for people to use instead of /proc or /sys.
12  *  See Documentation/DocBook/kernel-api for more details.
13  *
14  */
15 
16 #include <linux/module.h>
17 #include <linux/fs.h>
18 #include <linux/pagemap.h>
19 #include <linux/namei.h>
20 #include <linux/debugfs.h>
21 
22 static ssize_t default_read_file(struct file *file, char __user *buf,
23 				 size_t count, loff_t *ppos)
24 {
25 	return 0;
26 }
27 
28 static ssize_t default_write_file(struct file *file, const char __user *buf,
29 				   size_t count, loff_t *ppos)
30 {
31 	return count;
32 }
33 
34 static int default_open(struct inode *inode, struct file *file)
35 {
36 	if (inode->i_private)
37 		file->private_data = inode->i_private;
38 
39 	return 0;
40 }
41 
42 const struct file_operations debugfs_file_operations = {
43 	.read =		default_read_file,
44 	.write =	default_write_file,
45 	.open =		default_open,
46 };
47 
48 static void *debugfs_follow_link(struct dentry *dentry, struct nameidata *nd)
49 {
50 	nd_set_link(nd, dentry->d_inode->i_private);
51 	return NULL;
52 }
53 
54 const struct inode_operations debugfs_link_operations = {
55 	.readlink       = generic_readlink,
56 	.follow_link    = debugfs_follow_link,
57 };
58 
59 static void debugfs_u8_set(void *data, u64 val)
60 {
61 	*(u8 *)data = val;
62 }
63 static u64 debugfs_u8_get(void *data)
64 {
65 	return *(u8 *)data;
66 }
67 DEFINE_SIMPLE_ATTRIBUTE(fops_u8, debugfs_u8_get, debugfs_u8_set, "%llu\n");
68 
69 /**
70  * debugfs_create_u8 - create a debugfs file that is used to read and write an unsigned 8-bit value
71  * @name: a pointer to a string containing the name of the file to create.
72  * @mode: the permission that the file should have
73  * @parent: a pointer to the parent dentry for this file.  This should be a
74  *          directory dentry if set.  If this parameter is %NULL, then the
75  *          file will be created in the root of the debugfs filesystem.
76  * @value: a pointer to the variable that the file should read to and write
77  *         from.
78  *
79  * This function creates a file in debugfs with the given name that
80  * contains the value of the variable @value.  If the @mode variable is so
81  * set, it can be read from, and written to.
82  *
83  * This function will return a pointer to a dentry if it succeeds.  This
84  * pointer must be passed to the debugfs_remove() function when the file is
85  * to be removed (no automatic cleanup happens if your module is unloaded,
86  * you are responsible here.)  If an error occurs, %NULL will be returned.
87  *
88  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
89  * returned.  It is not wise to check for this value, but rather, check for
90  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
91  * code.
92  */
93 struct dentry *debugfs_create_u8(const char *name, mode_t mode,
94 				 struct dentry *parent, u8 *value)
95 {
96 	return debugfs_create_file(name, mode, parent, value, &fops_u8);
97 }
98 EXPORT_SYMBOL_GPL(debugfs_create_u8);
99 
100 static void debugfs_u16_set(void *data, u64 val)
101 {
102 	*(u16 *)data = val;
103 }
104 static u64 debugfs_u16_get(void *data)
105 {
106 	return *(u16 *)data;
107 }
108 DEFINE_SIMPLE_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu\n");
109 
110 /**
111  * debugfs_create_u16 - create a debugfs file that is used to read and write an unsigned 16-bit value
112  * @name: a pointer to a string containing the name of the file to create.
113  * @mode: the permission that the file should have
114  * @parent: a pointer to the parent dentry for this file.  This should be a
115  *          directory dentry if set.  If this parameter is %NULL, then the
116  *          file will be created in the root of the debugfs filesystem.
117  * @value: a pointer to the variable that the file should read to and write
118  *         from.
119  *
120  * This function creates a file in debugfs with the given name that
121  * contains the value of the variable @value.  If the @mode variable is so
122  * set, it can be read from, and written to.
123  *
124  * This function will return a pointer to a dentry if it succeeds.  This
125  * pointer must be passed to the debugfs_remove() function when the file is
126  * to be removed (no automatic cleanup happens if your module is unloaded,
127  * you are responsible here.)  If an error occurs, %NULL will be returned.
128  *
129  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
130  * returned.  It is not wise to check for this value, but rather, check for
131  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
132  * code.
133  */
134 struct dentry *debugfs_create_u16(const char *name, mode_t mode,
135 				  struct dentry *parent, u16 *value)
136 {
137 	return debugfs_create_file(name, mode, parent, value, &fops_u16);
138 }
139 EXPORT_SYMBOL_GPL(debugfs_create_u16);
140 
141 static void debugfs_u32_set(void *data, u64 val)
142 {
143 	*(u32 *)data = val;
144 }
145 static u64 debugfs_u32_get(void *data)
146 {
147 	return *(u32 *)data;
148 }
149 DEFINE_SIMPLE_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu\n");
150 
151 /**
152  * debugfs_create_u32 - create a debugfs file that is used to read and write an unsigned 32-bit value
153  * @name: a pointer to a string containing the name of the file to create.
154  * @mode: the permission that the file should have
155  * @parent: a pointer to the parent dentry for this file.  This should be a
156  *          directory dentry if set.  If this parameter is %NULL, then the
157  *          file will be created in the root of the debugfs filesystem.
158  * @value: a pointer to the variable that the file should read to and write
159  *         from.
160  *
161  * This function creates a file in debugfs with the given name that
162  * contains the value of the variable @value.  If the @mode variable is so
163  * set, it can be read from, and written to.
164  *
165  * This function will return a pointer to a dentry if it succeeds.  This
166  * pointer must be passed to the debugfs_remove() function when the file is
167  * to be removed (no automatic cleanup happens if your module is unloaded,
168  * you are responsible here.)  If an error occurs, %NULL will be returned.
169  *
170  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
171  * returned.  It is not wise to check for this value, but rather, check for
172  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
173  * code.
174  */
175 struct dentry *debugfs_create_u32(const char *name, mode_t mode,
176 				 struct dentry *parent, u32 *value)
177 {
178 	return debugfs_create_file(name, mode, parent, value, &fops_u32);
179 }
180 EXPORT_SYMBOL_GPL(debugfs_create_u32);
181 
182 static void debugfs_u64_set(void *data, u64 val)
183 {
184 	*(u64 *)data = val;
185 }
186 
187 static u64 debugfs_u64_get(void *data)
188 {
189 	return *(u64 *)data;
190 }
191 DEFINE_SIMPLE_ATTRIBUTE(fops_u64, debugfs_u64_get, debugfs_u64_set, "%llu\n");
192 
193 /**
194  * debugfs_create_u64 - create a debugfs file that is used to read and write an unsigned 64-bit value
195  * @name: a pointer to a string containing the name of the file to create.
196  * @mode: the permission that the file should have
197  * @parent: a pointer to the parent dentry for this file.  This should be a
198  *          directory dentry if set.  If this parameter is %NULL, then the
199  *          file will be created in the root of the debugfs filesystem.
200  * @value: a pointer to the variable that the file should read to and write
201  *         from.
202  *
203  * This function creates a file in debugfs with the given name that
204  * contains the value of the variable @value.  If the @mode variable is so
205  * set, it can be read from, and written to.
206  *
207  * This function will return a pointer to a dentry if it succeeds.  This
208  * pointer must be passed to the debugfs_remove() function when the file is
209  * to be removed (no automatic cleanup happens if your module is unloaded,
210  * you are responsible here.)  If an error occurs, %NULL will be returned.
211  *
212  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
213  * returned.  It is not wise to check for this value, but rather, check for
214  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
215  * code.
216  */
217 struct dentry *debugfs_create_u64(const char *name, mode_t mode,
218 				 struct dentry *parent, u64 *value)
219 {
220 	return debugfs_create_file(name, mode, parent, value, &fops_u64);
221 }
222 EXPORT_SYMBOL_GPL(debugfs_create_u64);
223 
224 static ssize_t read_file_bool(struct file *file, char __user *user_buf,
225 			      size_t count, loff_t *ppos)
226 {
227 	char buf[3];
228 	u32 *val = file->private_data;
229 
230 	if (*val)
231 		buf[0] = 'Y';
232 	else
233 		buf[0] = 'N';
234 	buf[1] = '\n';
235 	buf[2] = 0x00;
236 	return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
237 }
238 
239 static ssize_t write_file_bool(struct file *file, const char __user *user_buf,
240 			       size_t count, loff_t *ppos)
241 {
242 	char buf[32];
243 	int buf_size;
244 	u32 *val = file->private_data;
245 
246 	buf_size = min(count, (sizeof(buf)-1));
247 	if (copy_from_user(buf, user_buf, buf_size))
248 		return -EFAULT;
249 
250 	switch (buf[0]) {
251 	case 'y':
252 	case 'Y':
253 	case '1':
254 		*val = 1;
255 		break;
256 	case 'n':
257 	case 'N':
258 	case '0':
259 		*val = 0;
260 		break;
261 	}
262 
263 	return count;
264 }
265 
266 static const struct file_operations fops_bool = {
267 	.read =		read_file_bool,
268 	.write =	write_file_bool,
269 	.open =		default_open,
270 };
271 
272 /**
273  * debugfs_create_bool - create a debugfs file that is used to read and write a boolean value
274  * @name: a pointer to a string containing the name of the file to create.
275  * @mode: the permission that the file should have
276  * @parent: a pointer to the parent dentry for this file.  This should be a
277  *          directory dentry if set.  If this parameter is %NULL, then the
278  *          file will be created in the root of the debugfs filesystem.
279  * @value: a pointer to the variable that the file should read to and write
280  *         from.
281  *
282  * This function creates a file in debugfs with the given name that
283  * contains the value of the variable @value.  If the @mode variable is so
284  * set, it can be read from, and written to.
285  *
286  * This function will return a pointer to a dentry if it succeeds.  This
287  * pointer must be passed to the debugfs_remove() function when the file is
288  * to be removed (no automatic cleanup happens if your module is unloaded,
289  * you are responsible here.)  If an error occurs, %NULL will be returned.
290  *
291  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
292  * returned.  It is not wise to check for this value, but rather, check for
293  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
294  * code.
295  */
296 struct dentry *debugfs_create_bool(const char *name, mode_t mode,
297 				   struct dentry *parent, u32 *value)
298 {
299 	return debugfs_create_file(name, mode, parent, value, &fops_bool);
300 }
301 EXPORT_SYMBOL_GPL(debugfs_create_bool);
302 
303 static ssize_t read_file_blob(struct file *file, char __user *user_buf,
304 			      size_t count, loff_t *ppos)
305 {
306 	struct debugfs_blob_wrapper *blob = file->private_data;
307 	return simple_read_from_buffer(user_buf, count, ppos, blob->data,
308 			blob->size);
309 }
310 
311 static const struct file_operations fops_blob = {
312 	.read =		read_file_blob,
313 	.open =		default_open,
314 };
315 
316 /**
317  * debugfs_create_blob - create a debugfs file that is used to read and write a binary blob
318  * @name: a pointer to a string containing the name of the file to create.
319  * @mode: the permission that the file should have
320  * @parent: a pointer to the parent dentry for this file.  This should be a
321  *          directory dentry if set.  If this parameter is %NULL, then the
322  *          file will be created in the root of the debugfs filesystem.
323  * @blob: a pointer to a struct debugfs_blob_wrapper which contains a pointer
324  *        to the blob data and the size of the data.
325  *
326  * This function creates a file in debugfs with the given name that exports
327  * @blob->data as a binary blob. If the @mode variable is so set it can be
328  * read from. Writing is not supported.
329  *
330  * This function will return a pointer to a dentry if it succeeds.  This
331  * pointer must be passed to the debugfs_remove() function when the file is
332  * to be removed (no automatic cleanup happens if your module is unloaded,
333  * you are responsible here.)  If an error occurs, %NULL will be returned.
334  *
335  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
336  * returned.  It is not wise to check for this value, but rather, check for
337  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
338  * code.
339  */
340 struct dentry *debugfs_create_blob(const char *name, mode_t mode,
341 				   struct dentry *parent,
342 				   struct debugfs_blob_wrapper *blob)
343 {
344 	return debugfs_create_file(name, mode, parent, blob, &fops_blob);
345 }
346 EXPORT_SYMBOL_GPL(debugfs_create_blob);
347