fs/debugfs/file.c

   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/debugfs.h>
  20
  21 static ssize_t default_read_file(struct file *file, char __user *buf,
  22                                  size_t count, loff_t *ppos)
  23 {
  24         return 0;
  25 }
  26
  27 static ssize_t default_write_file(struct file *file, const char __user *buf,
  28                                    size_t count, loff_t *ppos)
  29 {
  30         return count;
  31 }
  32
  33 static int default_open(struct inode *inode, struct file *file)
  34 {
  35         if (inode->i_private)
  36                 file->private_data = inode->i_private;
  37
  38         return 0;
  39 }
  40
  41 const struct file_operations debugfs_file_operations = {
  42         .read =         default_read_file,
  43         .write =        default_write_file,
  44         .open =         default_open,
  45 };
  46
  47 static void debugfs_u8_set(void *data, u64 val)
  48 {
  49         *(u8 *)data = val;
  50 }
  51 static u64 debugfs_u8_get(void *data)
  52 {
  53         return *(u8 *)data;
  54 }
  55 DEFINE_SIMPLE_ATTRIBUTE(fops_u8, debugfs_u8_get, debugfs_u8_set, "%llu\n");
  56
  57 /**
  58  * debugfs_create_u8 - create a debugfs file that is used to read and write an unsigned 8-bit value
  59  * @name: a pointer to a string containing the name of the file to create.
  60  * @mode: the permission that the file should have
  61  * @parent: a pointer to the parent dentry for this file.  This should be a
  62  *          directory dentry if set.  If this parameter is %NULL, then the
  63  *          file will be created in the root of the debugfs filesystem.
  64  * @value: a pointer to the variable that the file should read to and write
  65  *         from.
  66  *
  67  * This function creates a file in debugfs with the given name that
  68  * contains the value of the variable @value.  If the @mode variable is so
  69  * set, it can be read from, and written to.
  70  *
  71  * This function will return a pointer to a dentry if it succeeds.  This
  72  * pointer must be passed to the debugfs_remove() function when the file is
  73  * to be removed (no automatic cleanup happens if your module is unloaded,
  74  * you are responsible here.)  If an error occurs, %NULL will be returned.
  75  *
  76  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
  77  * returned.  It is not wise to check for this value, but rather, check for
  78  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
  79  * code.
  80  */
  81 struct dentry *debugfs_create_u8(const char *name, mode_t mode,
  82                                  struct dentry *parent, u8 *value)
  83 {
  84         return debugfs_create_file(name, mode, parent, value, &fops_u8);
  85 }
  86 EXPORT_SYMBOL_GPL(debugfs_create_u8);
  87
  88 static void debugfs_u16_set(void *data, u64 val)
  89 {
  90         *(u16 *)data = val;
  91 }
  92 static u64 debugfs_u16_get(void *data)
  93 {
  94         return *(u16 *)data;
  95 }
  96 DEFINE_SIMPLE_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu\n");
  97
  98 /**
  99  * debugfs_create_u16 - create a debugfs file that is used to read and write an unsigned 16-bit value
 100  * @name: a pointer to a string containing the name of the file to create.
 101  * @mode: the permission that the file should have
 102  * @parent: a pointer to the parent dentry for this file.  This should be a
 103  *          directory dentry if set.  If this parameter is %NULL, then the
 104  *          file will be created in the root of the debugfs filesystem.
 105  * @value: a pointer to the variable that the file should read to and write
 106  *         from.
 107  *
 108  * This function creates a file in debugfs with the given name that
 109  * contains the value of the variable @value.  If the @mode variable is so
 110  * set, it can be read from, and written to.
 111  *
 112  * This function will return a pointer to a dentry if it succeeds.  This
 113  * pointer must be passed to the debugfs_remove() function when the file is
 114  * to be removed (no automatic cleanup happens if your module is unloaded,
 115  * you are responsible here.)  If an error occurs, %NULL will be returned.
 116  *
 117  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 118  * returned.  It is not wise to check for this value, but rather, check for
 119  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 120  * code.
 121  */
 122 struct dentry *debugfs_create_u16(const char *name, mode_t mode,
 123                                   struct dentry *parent, u16 *value)
 124 {
 125         return debugfs_create_file(name, mode, parent, value, &fops_u16);
 126 }
 127 EXPORT_SYMBOL_GPL(debugfs_create_u16);
 128
 129 static void debugfs_u32_set(void *data, u64 val)
 130 {
 131         *(u32 *)data = val;
 132 }
 133 static u64 debugfs_u32_get(void *data)
 134 {
 135         return *(u32 *)data;
 136 }
 137 DEFINE_SIMPLE_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu\n");
 138
 139 /**
 140  * debugfs_create_u32 - create a debugfs file that is used to read and write an unsigned 32-bit value
 141  * @name: a pointer to a string containing the name of the file to create.
 142  * @mode: the permission that the file should have
 143  * @parent: a pointer to the parent dentry for this file.  This should be a
 144  *          directory dentry if set.  If this parameter is %NULL, then the
 145  *          file will be created in the root of the debugfs filesystem.
 146  * @value: a pointer to the variable that the file should read to and write
 147  *         from.
 148  *
 149  * This function creates a file in debugfs with the given name that
 150  * contains the value of the variable @value.  If the @mode variable is so
 151  * set, it can be read from, and written to.
 152  *
 153  * This function will return a pointer to a dentry if it succeeds.  This
 154  * pointer must be passed to the debugfs_remove() function when the file is
 155  * to be removed (no automatic cleanup happens if your module is unloaded,
 156  * you are responsible here.)  If an error occurs, %NULL will be returned.
 157  *
 158  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 159  * returned.  It is not wise to check for this value, but rather, check for
 160  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 161  * code.
 162  */
 163 struct dentry *debugfs_create_u32(const char *name, mode_t mode,
 164                                  struct dentry *parent, u32 *value)
 165 {
 166         return debugfs_create_file(name, mode, parent, value, &fops_u32);
 167 }
 168 EXPORT_SYMBOL_GPL(debugfs_create_u32);
 169
 170 static ssize_t read_file_bool(struct file *file, char __user *user_buf,
 171                               size_t count, loff_t *ppos)
 172 {
 173         char buf[3];
 174         u32 *val = file->private_data;
 175
 176         if (*val)
 177                 buf[0] = 'Y';
 178         else
 179                 buf[0] = 'N';
 180         buf[1] = '\n';
 181         buf[2] = 0x00;
 182         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
 183 }
 184
 185 static ssize_t write_file_bool(struct file *file, const char __user *user_buf,
 186                                size_t count, loff_t *ppos)
 187 {
 188         char buf[32];
 189         int buf_size;
 190         u32 *val = file->private_data;
 191
 192         buf_size = min(count, (sizeof(buf)-1));
 193         if (copy_from_user(buf, user_buf, buf_size))
 194                 return -EFAULT;
 195
 196         switch (buf[0]) {
 197         case 'y':
 198         case 'Y':
 199         case '1':
 200                 *val = 1;
 201                 break;
 202         case 'n':
 203         case 'N':
 204         case '0':
 205                 *val = 0;
 206                 break;
 207         }
 208
 209         return count;
 210 }
 211
 212 static const struct file_operations fops_bool = {
 213         .read =         read_file_bool,
 214         .write =        write_file_bool,
 215         .open =         default_open,
 216 };
 217
 218 /**
 219  * debugfs_create_bool - create a debugfs file that is used to read and write a boolean value
 220  * @name: a pointer to a string containing the name of the file to create.
 221  * @mode: the permission that the file should have
 222  * @parent: a pointer to the parent dentry for this file.  This should be a
 223  *          directory dentry if set.  If this parameter is %NULL, then the
 224  *          file will be created in the root of the debugfs filesystem.
 225  * @value: a pointer to the variable that the file should read to and write
 226  *         from.
 227  *
 228  * This function creates a file in debugfs with the given name that
 229  * contains the value of the variable @value.  If the @mode variable is so
 230  * set, it can be read from, and written to.
 231  *
 232  * This function will return a pointer to a dentry if it succeeds.  This
 233  * pointer must be passed to the debugfs_remove() function when the file is
 234  * to be removed (no automatic cleanup happens if your module is unloaded,
 235  * you are responsible here.)  If an error occurs, %NULL will be returned.
 236  *
 237  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 238  * returned.  It is not wise to check for this value, but rather, check for
 239  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 240  * code.
 241  */
 242 struct dentry *debugfs_create_bool(const char *name, mode_t mode,
 243                                    struct dentry *parent, u32 *value)
 244 {
 245         return debugfs_create_file(name, mode, parent, value, &fops_bool);
 246 }
 247 EXPORT_SYMBOL_GPL(debugfs_create_bool);
 248
 249 static ssize_t read_file_blob(struct file *file, char __user *user_buf,
 250                               size_t count, loff_t *ppos)
 251 {
 252         struct debugfs_blob_wrapper *blob = file->private_data;
 253         return simple_read_from_buffer(user_buf, count, ppos, blob->data,
 254                         blob->size);
 255 }
 256
 257 static const struct file_operations fops_blob = {
 258         .read =         read_file_blob,
 259         .open =         default_open,
 260 };
 261
 262 /**
 263  * debugfs_create_blob - create a debugfs file that is used to read and write a binary blob
 264  * @name: a pointer to a string containing the name of the file to create.
 265  * @mode: the permission that the file should have
 266  * @parent: a pointer to the parent dentry for this file.  This should be a
 267  *          directory dentry if set.  If this parameter is %NULL, then the
 268  *          file will be created in the root of the debugfs filesystem.
 269  * @blob: a pointer to a struct debugfs_blob_wrapper which contains a pointer
 270  *        to the blob data and the size of the data.
 271  *
 272  * This function creates a file in debugfs with the given name that exports
 273  * @blob->data as a binary blob. If the @mode variable is so set it can be
 274  * read from. Writing is not supported.
 275  *
 276  * This function will return a pointer to a dentry if it succeeds.  This
 277  * pointer must be passed to the debugfs_remove() function when the file is
 278  * to be removed (no automatic cleanup happens if your module is unloaded,
 279  * you are responsible here.)  If an error occurs, %NULL will be returned.
 280  *
 281  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 282  * returned.  It is not wise to check for this value, but rather, check for
 283  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 284  * code.
 285  */
 286 struct dentry *debugfs_create_blob(const char *name, mode_t mode,
 287                                    struct dentry *parent,
 288                                    struct debugfs_blob_wrapper *blob)
 289 {
 290         return debugfs_create_file(name, mode, parent, blob, &fops_blob);
 291 }
 292 EXPORT_SYMBOL_GPL(debugfs_create_blob);