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 int debugfs_u8_set(void *data, u64 val)
  60 {
  61         *(u8 *)data = val;
  62         return 0;
  63 }
  64 static int debugfs_u8_get(void *data, u64 *val)
  65 {
  66         *val = *(u8 *)data;
  67         return 0;
  68 }
  69 DEFINE_SIMPLE_ATTRIBUTE(fops_u8, debugfs_u8_get, debugfs_u8_set, "%llu\n");
  70
  71 /**
  72  * debugfs_create_u8 - create a debugfs file that is used to read and write an unsigned 8-bit value
  73  * @name: a pointer to a string containing the name of the file to create.
  74  * @mode: the permission that the file should have
  75  * @parent: a pointer to the parent dentry for this file.  This should be a
  76  *          directory dentry if set.  If this parameter is %NULL, then the
  77  *          file will be created in the root of the debugfs filesystem.
  78  * @value: a pointer to the variable that the file should read to and write
  79  *         from.
  80  *
  81  * This function creates a file in debugfs with the given name that
  82  * contains the value of the variable @value.  If the @mode variable is so
  83  * set, it can be read from, and written to.
  84  *
  85  * This function will return a pointer to a dentry if it succeeds.  This
  86  * pointer must be passed to the debugfs_remove() function when the file is
  87  * to be removed (no automatic cleanup happens if your module is unloaded,
  88  * you are responsible here.)  If an error occurs, %NULL will be returned.
  89  *
  90  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
  91  * returned.  It is not wise to check for this value, but rather, check for
  92  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
  93  * code.
  94  */
  95 struct dentry *debugfs_create_u8(const char *name, mode_t mode,
  96                                  struct dentry *parent, u8 *value)
  97 {
  98         return debugfs_create_file(name, mode, parent, value, &fops_u8);
  99 }
 100 EXPORT_SYMBOL_GPL(debugfs_create_u8);
 101
 102 static int debugfs_u16_set(void *data, u64 val)
 103 {
 104         *(u16 *)data = val;
 105         return 0;
 106 }
 107 static int debugfs_u16_get(void *data, u64 *val)
 108 {
 109         *val = *(u16 *)data;
 110         return 0;
 111 }
 112 DEFINE_SIMPLE_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu\n");
 113
 114 /**
 115  * debugfs_create_u16 - create a debugfs file that is used to read and write an unsigned 16-bit value
 116  * @name: a pointer to a string containing the name of the file to create.
 117  * @mode: the permission that the file should have
 118  * @parent: a pointer to the parent dentry for this file.  This should be a
 119  *          directory dentry if set.  If this parameter is %NULL, then the
 120  *          file will be created in the root of the debugfs filesystem.
 121  * @value: a pointer to the variable that the file should read to and write
 122  *         from.
 123  *
 124  * This function creates a file in debugfs with the given name that
 125  * contains the value of the variable @value.  If the @mode variable is so
 126  * set, it can be read from, and written to.
 127  *
 128  * This function will return a pointer to a dentry if it succeeds.  This
 129  * pointer must be passed to the debugfs_remove() function when the file is
 130  * to be removed (no automatic cleanup happens if your module is unloaded,
 131  * you are responsible here.)  If an error occurs, %NULL will be returned.
 132  *
 133  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 134  * returned.  It is not wise to check for this value, but rather, check for
 135  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 136  * code.
 137  */
 138 struct dentry *debugfs_create_u16(const char *name, mode_t mode,
 139                                   struct dentry *parent, u16 *value)
 140 {
 141         return debugfs_create_file(name, mode, parent, value, &fops_u16);
 142 }
 143 EXPORT_SYMBOL_GPL(debugfs_create_u16);
 144
 145 static int debugfs_u32_set(void *data, u64 val)
 146 {
 147         *(u32 *)data = val;
 148         return 0;
 149 }
 150 static int debugfs_u32_get(void *data, u64 *val)
 151 {
 152         *val = *(u32 *)data;
 153         return 0;
 154 }
 155 DEFINE_SIMPLE_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu\n");
 156
 157 /**
 158  * debugfs_create_u32 - create a debugfs file that is used to read and write an unsigned 32-bit value
 159  * @name: a pointer to a string containing the name of the file to create.
 160  * @mode: the permission that the file should have
 161  * @parent: a pointer to the parent dentry for this file.  This should be a
 162  *          directory dentry if set.  If this parameter is %NULL, then the
 163  *          file will be created in the root of the debugfs filesystem.
 164  * @value: a pointer to the variable that the file should read to and write
 165  *         from.
 166  *
 167  * This function creates a file in debugfs with the given name that
 168  * contains the value of the variable @value.  If the @mode variable is so
 169  * set, it can be read from, and written to.
 170  *
 171  * This function will return a pointer to a dentry if it succeeds.  This
 172  * pointer must be passed to the debugfs_remove() function when the file is
 173  * to be removed (no automatic cleanup happens if your module is unloaded,
 174  * you are responsible here.)  If an error occurs, %NULL will be returned.
 175  *
 176  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 177  * returned.  It is not wise to check for this value, but rather, check for
 178  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 179  * code.
 180  */
 181 struct dentry *debugfs_create_u32(const char *name, mode_t mode,
 182                                  struct dentry *parent, u32 *value)
 183 {
 184         return debugfs_create_file(name, mode, parent, value, &fops_u32);
 185 }
 186 EXPORT_SYMBOL_GPL(debugfs_create_u32);
 187
 188 static int debugfs_u64_set(void *data, u64 val)
 189 {
 190         *(u64 *)data = val;
 191         return 0;
 192 }
 193
 194 static int debugfs_u64_get(void *data, u64 *val)
 195 {
 196         *val = *(u64 *)data;
 197         return 0;
 198 }
 199 DEFINE_SIMPLE_ATTRIBUTE(fops_u64, debugfs_u64_get, debugfs_u64_set, "%llu\n");
 200
 201 /**
 202  * debugfs_create_u64 - create a debugfs file that is used to read and write an unsigned 64-bit value
 203  * @name: a pointer to a string containing the name of the file to create.
 204  * @mode: the permission that the file should have
 205  * @parent: a pointer to the parent dentry for this file.  This should be a
 206  *          directory dentry if set.  If this parameter is %NULL, then the
 207  *          file will be created in the root of the debugfs filesystem.
 208  * @value: a pointer to the variable that the file should read to and write
 209  *         from.
 210  *
 211  * This function creates a file in debugfs with the given name that
 212  * contains the value of the variable @value.  If the @mode variable is so
 213  * set, it can be read from, and written to.
 214  *
 215  * This function will return a pointer to a dentry if it succeeds.  This
 216  * pointer must be passed to the debugfs_remove() function when the file is
 217  * to be removed (no automatic cleanup happens if your module is unloaded,
 218  * you are responsible here.)  If an error occurs, %NULL will be returned.
 219  *
 220  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 221  * returned.  It is not wise to check for this value, but rather, check for
 222  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 223  * code.
 224  */
 225 struct dentry *debugfs_create_u64(const char *name, mode_t mode,
 226                                  struct dentry *parent, u64 *value)
 227 {
 228         return debugfs_create_file(name, mode, parent, value, &fops_u64);
 229 }
 230 EXPORT_SYMBOL_GPL(debugfs_create_u64);
 231
 232 DEFINE_SIMPLE_ATTRIBUTE(fops_x8, debugfs_u8_get, debugfs_u8_set, "0x%02llx\n");
 233
 234 DEFINE_SIMPLE_ATTRIBUTE(fops_x16, debugfs_u16_get, debugfs_u16_set, "0x%04llx\n");
 235
 236 DEFINE_SIMPLE_ATTRIBUTE(fops_x32, debugfs_u32_get, debugfs_u32_set, "0x%08llx\n");
 237
 238 /*
 239  * debugfs_create_x{8,16,32} - create a debugfs file that is used to read and write an unsigned {8,16,32}-bit value
 240  *
 241  * These functions are exactly the same as the above functions (but use a hex
 242  * output for the decimal challenged). For details look at the above unsigned
 243  * decimal functions.
 244  */
 245
 246 /**
 247  * debugfs_create_x8 - create a debugfs file that is used to read and write an unsigned 8-bit value
 248  * @name: a pointer to a string containing the name of the file to create.
 249  * @mode: the permission that the file should have
 250  * @parent: a pointer to the parent dentry for this file.  This should be a
 251  *          directory dentry if set.  If this parameter is %NULL, then the
 252  *          file will be created in the root of the debugfs filesystem.
 253  * @value: a pointer to the variable that the file should read to and write
 254  *         from.
 255  */
 256 struct dentry *debugfs_create_x8(const char *name, mode_t mode,
 257                                  struct dentry *parent, u8 *value)
 258 {
 259         return debugfs_create_file(name, mode, parent, value, &fops_x8);
 260 }
 261 EXPORT_SYMBOL_GPL(debugfs_create_x8);
 262
 263 /**
 264  * debugfs_create_x16 - create a debugfs file that is used to read and write an unsigned 16-bit value
 265  * @name: a pointer to a string containing the name of the file to create.
 266  * @mode: the permission that the file should have
 267  * @parent: a pointer to the parent dentry for this file.  This should be a
 268  *          directory dentry if set.  If this parameter is %NULL, then the
 269  *          file will be created in the root of the debugfs filesystem.
 270  * @value: a pointer to the variable that the file should read to and write
 271  *         from.
 272  */
 273 struct dentry *debugfs_create_x16(const char *name, mode_t mode,
 274                                  struct dentry *parent, u16 *value)
 275 {
 276         return debugfs_create_file(name, mode, parent, value, &fops_x16);
 277 }
 278 EXPORT_SYMBOL_GPL(debugfs_create_x16);
 279
 280 /**
 281  * debugfs_create_x32 - create a debugfs file that is used to read and write an unsigned 32-bit value
 282  * @name: a pointer to a string containing the name of the file to create.
 283  * @mode: the permission that the file should have
 284  * @parent: a pointer to the parent dentry for this file.  This should be a
 285  *          directory dentry if set.  If this parameter is %NULL, then the
 286  *          file will be created in the root of the debugfs filesystem.
 287  * @value: a pointer to the variable that the file should read to and write
 288  *         from.
 289  */
 290 struct dentry *debugfs_create_x32(const char *name, mode_t mode,
 291                                  struct dentry *parent, u32 *value)
 292 {
 293         return debugfs_create_file(name, mode, parent, value, &fops_x32);
 294 }
 295 EXPORT_SYMBOL_GPL(debugfs_create_x32);
 296
 297 static ssize_t read_file_bool(struct file *file, char __user *user_buf,
 298                               size_t count, loff_t *ppos)
 299 {
 300         char buf[3];
 301         u32 *val = file->private_data;
 302
 303         if (*val)
 304                 buf[0] = 'Y';
 305         else
 306                 buf[0] = 'N';
 307         buf[1] = '\n';
 308         buf[2] = 0x00;
 309         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
 310 }
 311
 312 static ssize_t write_file_bool(struct file *file, const char __user *user_buf,
 313                                size_t count, loff_t *ppos)
 314 {
 315         char buf[32];
 316         int buf_size;
 317         u32 *val = file->private_data;
 318
 319         buf_size = min(count, (sizeof(buf)-1));
 320         if (copy_from_user(buf, user_buf, buf_size))
 321                 return -EFAULT;
 322
 323         switch (buf[0]) {
 324         case 'y':
 325         case 'Y':
 326         case '1':
 327                 *val = 1;
 328                 break;
 329         case 'n':
 330         case 'N':
 331         case '0':
 332                 *val = 0;
 333                 break;
 334         }
 335
 336         return count;
 337 }
 338
 339 static const struct file_operations fops_bool = {
 340         .read =         read_file_bool,
 341         .write =        write_file_bool,
 342         .open =         default_open,
 343 };
 344
 345 /**
 346  * debugfs_create_bool - create a debugfs file that is used to read and write a boolean value
 347  * @name: a pointer to a string containing the name of the file to create.
 348  * @mode: the permission that the file should have
 349  * @parent: a pointer to the parent dentry for this file.  This should be a
 350  *          directory dentry if set.  If this parameter is %NULL, then the
 351  *          file will be created in the root of the debugfs filesystem.
 352  * @value: a pointer to the variable that the file should read to and write
 353  *         from.
 354  *
 355  * This function creates a file in debugfs with the given name that
 356  * contains the value of the variable @value.  If the @mode variable is so
 357  * set, it can be read from, and written to.
 358  *
 359  * This function will return a pointer to a dentry if it succeeds.  This
 360  * pointer must be passed to the debugfs_remove() function when the file is
 361  * to be removed (no automatic cleanup happens if your module is unloaded,
 362  * you are responsible here.)  If an error occurs, %NULL will be returned.
 363  *
 364  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 365  * returned.  It is not wise to check for this value, but rather, check for
 366  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 367  * code.
 368  */
 369 struct dentry *debugfs_create_bool(const char *name, mode_t mode,
 370                                    struct dentry *parent, u32 *value)
 371 {
 372         return debugfs_create_file(name, mode, parent, value, &fops_bool);
 373 }
 374 EXPORT_SYMBOL_GPL(debugfs_create_bool);
 375
 376 static ssize_t read_file_blob(struct file *file, char __user *user_buf,
 377                               size_t count, loff_t *ppos)
 378 {
 379         struct debugfs_blob_wrapper *blob = file->private_data;
 380         return simple_read_from_buffer(user_buf, count, ppos, blob->data,
 381                         blob->size);
 382 }
 383
 384 static const struct file_operations fops_blob = {
 385         .read =         read_file_blob,
 386         .open =         default_open,
 387 };
 388
 389 /**
 390  * debugfs_create_blob - create a debugfs file that is used to read and write a binary blob
 391  * @name: a pointer to a string containing the name of the file to create.
 392  * @mode: the permission that the file should have
 393  * @parent: a pointer to the parent dentry for this file.  This should be a
 394  *          directory dentry if set.  If this parameter is %NULL, then the
 395  *          file will be created in the root of the debugfs filesystem.
 396  * @blob: a pointer to a struct debugfs_blob_wrapper which contains a pointer
 397  *        to the blob data and the size of the data.
 398  *
 399  * This function creates a file in debugfs with the given name that exports
 400  * @blob->data as a binary blob. If the @mode variable is so set it can be
 401  * read from. Writing is not supported.
 402  *
 403  * This function will return a pointer to a dentry if it succeeds.  This
 404  * pointer must be passed to the debugfs_remove() function when the file is
 405  * to be removed (no automatic cleanup happens if your module is unloaded,
 406  * you are responsible here.)  If an error occurs, %NULL will be returned.
 407  *
 408  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 409  * returned.  It is not wise to check for this value, but rather, check for
 410  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 411  * code.
 412  */
 413 struct dentry *debugfs_create_blob(const char *name, mode_t mode,
 414                                    struct dentry *parent,
 415                                    struct debugfs_blob_wrapper *blob)
 416 {
 417         return debugfs_create_file(name, mode, parent, blob, &fops_blob);
 418 }
 419 EXPORT_SYMBOL_GPL(debugfs_create_blob);