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/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 ssize_t read_file_bool(struct file *file, char __user *user_buf,
 183                               size_t count, loff_t *ppos)
 184 {
 185         char buf[3];
 186         u32 *val = file->private_data;
 187
 188         if (*val)
 189                 buf[0] = 'Y';
 190         else
 191                 buf[0] = 'N';
 192         buf[1] = '\n';
 193         buf[2] = 0x00;
 194         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
 195 }
 196
 197 static ssize_t write_file_bool(struct file *file, const char __user *user_buf,
 198                                size_t count, loff_t *ppos)
 199 {
 200         char buf[32];
 201         int buf_size;
 202         u32 *val = file->private_data;
 203
 204         buf_size = min(count, (sizeof(buf)-1));
 205         if (copy_from_user(buf, user_buf, buf_size))
 206                 return -EFAULT;
 207
 208         switch (buf[0]) {
 209         case 'y':
 210         case 'Y':
 211         case '1':
 212                 *val = 1;
 213                 break;
 214         case 'n':
 215         case 'N':
 216         case '0':
 217                 *val = 0;
 218                 break;
 219         }
 220
 221         return count;
 222 }
 223
 224 static const struct file_operations fops_bool = {
 225         .read =         read_file_bool,
 226         .write =        write_file_bool,
 227         .open =         default_open,
 228 };
 229
 230 /**
 231  * debugfs_create_bool - create a debugfs file that is used to read and write a boolean value
 232  * @name: a pointer to a string containing the name of the file to create.
 233  * @mode: the permission that the file should have
 234  * @parent: a pointer to the parent dentry for this file.  This should be a
 235  *          directory dentry if set.  If this parameter is %NULL, then the
 236  *          file will be created in the root of the debugfs filesystem.
 237  * @value: a pointer to the variable that the file should read to and write
 238  *         from.
 239  *
 240  * This function creates a file in debugfs with the given name that
 241  * contains the value of the variable @value.  If the @mode variable is so
 242  * set, it can be read from, and written to.
 243  *
 244  * This function will return a pointer to a dentry if it succeeds.  This
 245  * pointer must be passed to the debugfs_remove() function when the file is
 246  * to be removed (no automatic cleanup happens if your module is unloaded,
 247  * you are responsible here.)  If an error occurs, %NULL will be returned.
 248  *
 249  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 250  * returned.  It is not wise to check for this value, but rather, check for
 251  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 252  * code.
 253  */
 254 struct dentry *debugfs_create_bool(const char *name, mode_t mode,
 255                                    struct dentry *parent, u32 *value)
 256 {
 257         return debugfs_create_file(name, mode, parent, value, &fops_bool);
 258 }
 259 EXPORT_SYMBOL_GPL(debugfs_create_bool);
 260
 261 static ssize_t read_file_blob(struct file *file, char __user *user_buf,
 262                               size_t count, loff_t *ppos)
 263 {
 264         struct debugfs_blob_wrapper *blob = file->private_data;
 265         return simple_read_from_buffer(user_buf, count, ppos, blob->data,
 266                         blob->size);
 267 }
 268
 269 static const struct file_operations fops_blob = {
 270         .read =         read_file_blob,
 271         .open =         default_open,
 272 };
 273
 274 /**
 275  * debugfs_create_blob - create a debugfs file that is used to read and write a binary blob
 276  * @name: a pointer to a string containing the name of the file to create.
 277  * @mode: the permission that the file should have
 278  * @parent: a pointer to the parent dentry for this file.  This should be a
 279  *          directory dentry if set.  If this parameter is %NULL, then the
 280  *          file will be created in the root of the debugfs filesystem.
 281  * @blob: a pointer to a struct debugfs_blob_wrapper which contains a pointer
 282  *        to the blob data and the size of the data.
 283  *
 284  * This function creates a file in debugfs with the given name that exports
 285  * @blob->data as a binary blob. If the @mode variable is so set it can be
 286  * read from. Writing is not supported.
 287  *
 288  * This function will return a pointer to a dentry if it succeeds.  This
 289  * pointer must be passed to the debugfs_remove() function when the file is
 290  * to be removed (no automatic cleanup happens if your module is unloaded,
 291  * you are responsible here.)  If an error occurs, %NULL will be returned.
 292  *
 293  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 294  * returned.  It is not wise to check for this value, but rather, check for
 295  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 296  * code.
 297  */
 298 struct dentry *debugfs_create_blob(const char *name, mode_t mode,
 299                                    struct dentry *parent,
 300                                    struct debugfs_blob_wrapper *blob)
 301 {
 302         return debugfs_create_file(name, mode, parent, blob, &fops_blob);
 303 }
 304 EXPORT_SYMBOL_GPL(debugfs_create_blob);