xref: /openbmc/linux/fs/debugfs/file.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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/config.h>
17 #include <linux/module.h>
18 #include <linux/fs.h>
19 #include <linux/pagemap.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->u.generic_ip)
37 		file->private_data = inode->u.generic_ip;
38 
39 	return 0;
40 }
41 
42 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_u8_set(void *data, u64 val)
49 {
50 	*(u8 *)data = val;
51 }
52 static u64 debugfs_u8_get(void *data)
53 {
54 	return *(u8 *)data;
55 }
56 DEFINE_SIMPLE_ATTRIBUTE(fops_u8, debugfs_u8_get, debugfs_u8_set, "%llu\n");
57 
58 /**
59  * debugfs_create_u8 - create a file in the debugfs filesystem that is used to read and write a unsigned 8 bit value.
60  *
61  * @name: a pointer to a string containing the name of the file to create.
62  * @mode: the permission that the file should have
63  * @parent: a pointer to the parent dentry for this file.  This should be a
64  *          directory dentry if set.  If this paramater is NULL, then the
65  *          file will be created in the root of the debugfs filesystem.
66  * @value: a pointer to the variable that the file should read to and write
67  *         from.
68  *
69  * This function creates a file in debugfs with the given name that
70  * contains the value of the variable @value.  If the @mode variable is so
71  * set, it can be read from, and written to.
72  *
73  * This function will return a pointer to a dentry if it succeeds.  This
74  * pointer must be passed to the debugfs_remove() function when the file is
75  * to be removed (no automatic cleanup happens if your module is unloaded,
76  * you are responsible here.)  If an error occurs, NULL will be returned.
77  *
78  * If debugfs is not enabled in the kernel, the value -ENODEV will be
79  * returned.  It is not wise to check for this value, but rather, check for
80  * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
81  * code.
82  */
83 struct dentry *debugfs_create_u8(const char *name, mode_t mode,
84 				 struct dentry *parent, u8 *value)
85 {
86 	return debugfs_create_file(name, mode, parent, value, &fops_u8);
87 }
88 EXPORT_SYMBOL_GPL(debugfs_create_u8);
89 
90 static void debugfs_u16_set(void *data, u64 val)
91 {
92 	*(u16 *)data = val;
93 }
94 static u64 debugfs_u16_get(void *data)
95 {
96 	return *(u16 *)data;
97 }
98 DEFINE_SIMPLE_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu\n");
99 
100 /**
101  * debugfs_create_u16 - create a file in the debugfs filesystem that is used to read and write a unsigned 8 bit value.
102  *
103  * @name: a pointer to a string containing the name of the file to create.
104  * @mode: the permission that the file should have
105  * @parent: a pointer to the parent dentry for this file.  This should be a
106  *          directory dentry if set.  If this paramater is NULL, then the
107  *          file will be created in the root of the debugfs filesystem.
108  * @value: a pointer to the variable that the file should read to and write
109  *         from.
110  *
111  * This function creates a file in debugfs with the given name that
112  * contains the value of the variable @value.  If the @mode variable is so
113  * set, it can be read from, and written to.
114  *
115  * This function will return a pointer to a dentry if it succeeds.  This
116  * pointer must be passed to the debugfs_remove() function when the file is
117  * to be removed (no automatic cleanup happens if your module is unloaded,
118  * you are responsible here.)  If an error occurs, NULL will be returned.
119  *
120  * If debugfs is not enabled in the kernel, the value -ENODEV will be
121  * returned.  It is not wise to check for this value, but rather, check for
122  * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
123  * code.
124  */
125 struct dentry *debugfs_create_u16(const char *name, mode_t mode,
126 				  struct dentry *parent, u16 *value)
127 {
128 	return debugfs_create_file(name, mode, parent, value, &fops_u16);
129 }
130 EXPORT_SYMBOL_GPL(debugfs_create_u16);
131 
132 static void debugfs_u32_set(void *data, u64 val)
133 {
134 	*(u32 *)data = val;
135 }
136 static u64 debugfs_u32_get(void *data)
137 {
138 	return *(u32 *)data;
139 }
140 DEFINE_SIMPLE_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu\n");
141 
142 /**
143  * debugfs_create_u32 - create a file in the debugfs filesystem that is used to read and write a unsigned 8 bit value.
144  *
145  * @name: a pointer to a string containing the name of the file to create.
146  * @mode: the permission that the file should have
147  * @parent: a pointer to the parent dentry for this file.  This should be a
148  *          directory dentry if set.  If this paramater is NULL, then the
149  *          file will be created in the root of the debugfs filesystem.
150  * @value: a pointer to the variable that the file should read to and write
151  *         from.
152  *
153  * This function creates a file in debugfs with the given name that
154  * contains the value of the variable @value.  If the @mode variable is so
155  * set, it can be read from, and written to.
156  *
157  * This function will return a pointer to a dentry if it succeeds.  This
158  * pointer must be passed to the debugfs_remove() function when the file is
159  * to be removed (no automatic cleanup happens if your module is unloaded,
160  * you are responsible here.)  If an error occurs, NULL will be returned.
161  *
162  * If debugfs is not enabled in the kernel, the value -ENODEV will be
163  * returned.  It is not wise to check for this value, but rather, check for
164  * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
165  * code.
166  */
167 struct dentry *debugfs_create_u32(const char *name, mode_t mode,
168 				 struct dentry *parent, u32 *value)
169 {
170 	return debugfs_create_file(name, mode, parent, value, &fops_u32);
171 }
172 EXPORT_SYMBOL_GPL(debugfs_create_u32);
173 
174 static ssize_t read_file_bool(struct file *file, char __user *user_buf,
175 			      size_t count, loff_t *ppos)
176 {
177 	char buf[3];
178 	u32 *val = file->private_data;
179 
180 	if (*val)
181 		buf[0] = 'Y';
182 	else
183 		buf[0] = 'N';
184 	buf[1] = '\n';
185 	buf[2] = 0x00;
186 	return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
187 }
188 
189 static ssize_t write_file_bool(struct file *file, const char __user *user_buf,
190 			       size_t count, loff_t *ppos)
191 {
192 	char buf[32];
193 	int buf_size;
194 	u32 *val = file->private_data;
195 
196 	buf_size = min(count, (sizeof(buf)-1));
197 	if (copy_from_user(buf, user_buf, buf_size))
198 		return -EFAULT;
199 
200 	switch (buf[0]) {
201 	case 'y':
202 	case 'Y':
203 	case '1':
204 		*val = 1;
205 		break;
206 	case 'n':
207 	case 'N':
208 	case '0':
209 		*val = 0;
210 		break;
211 	}
212 
213 	return count;
214 }
215 
216 static struct file_operations fops_bool = {
217 	.read =		read_file_bool,
218 	.write =	write_file_bool,
219 	.open =		default_open,
220 };
221 
222 /**
223  * debugfs_create_bool - create a file in the debugfs filesystem that is used to read and write a boolean value.
224  *
225  * @name: a pointer to a string containing the name of the file to create.
226  * @mode: the permission that the file should have
227  * @parent: a pointer to the parent dentry for this file.  This should be a
228  *          directory dentry if set.  If this paramater is NULL, then the
229  *          file will be created in the root of the debugfs filesystem.
230  * @value: a pointer to the variable that the file should read to and write
231  *         from.
232  *
233  * This function creates a file in debugfs with the given name that
234  * contains the value of the variable @value.  If the @mode variable is so
235  * set, it can be read from, and written to.
236  *
237  * This function will return a pointer to a dentry if it succeeds.  This
238  * pointer must be passed to the debugfs_remove() function when the file is
239  * to be removed (no automatic cleanup happens if your module is unloaded,
240  * you are responsible here.)  If an error occurs, NULL will be returned.
241  *
242  * If debugfs is not enabled in the kernel, the value -ENODEV will be
243  * returned.  It is not wise to check for this value, but rather, check for
244  * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
245  * code.
246  */
247 struct dentry *debugfs_create_bool(const char *name, mode_t mode,
248 				   struct dentry *parent, u32 *value)
249 {
250 	return debugfs_create_file(name, mode, parent, value, &fops_bool);
251 }
252 EXPORT_SYMBOL_GPL(debugfs_create_bool);
253 
254