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