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/filesystems 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 DEFINE_SIMPLE_ATTRIBUTE(fops_u8_ro, debugfs_u8_get, NULL, "%llu\n");
  71 DEFINE_SIMPLE_ATTRIBUTE(fops_u8_wo, NULL, debugfs_u8_set, "%llu\n");
  72
  73 /**
  74  * debugfs_create_u8 - create a debugfs file that is used to read and write an unsigned 8-bit value
  75  * @name: a pointer to a string containing the name of the file to create.
  76  * @mode: the permission that the file should have
  77  * @parent: a pointer to the parent dentry for this file.  This should be a
  78  *          directory dentry if set.  If this parameter is %NULL, then the
  79  *          file will be created in the root of the debugfs filesystem.
  80  * @value: a pointer to the variable that the file should read to and write
  81  *         from.
  82  *
  83  * This function creates a file in debugfs with the given name that
  84  * contains the value of the variable @value.  If the @mode variable is so
  85  * set, it can be read from, and written to.
  86  *
  87  * This function will return a pointer to a dentry if it succeeds.  This
  88  * pointer must be passed to the debugfs_remove() function when the file is
  89  * to be removed (no automatic cleanup happens if your module is unloaded,
  90  * you are responsible here.)  If an error occurs, %NULL will be returned.
  91  *
  92  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
  93  * returned.  It is not wise to check for this value, but rather, check for
  94  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
  95  * code.
  96  */
  97 struct dentry *debugfs_create_u8(const char *name, mode_t mode,
  98                                  struct dentry *parent, u8 *value)
  99 {
 100         /* if there are no write bits set, make read only */
 101         if (!(mode & S_IWUGO))
 102                 return debugfs_create_file(name, mode, parent, value, &fops_u8_ro);
 103         /* if there are no read bits set, make write only */
 104         if (!(mode & S_IRUGO))
 105                 return debugfs_create_file(name, mode, parent, value, &fops_u8_wo);
 106
 107         return debugfs_create_file(name, mode, parent, value, &fops_u8);
 108 }
 109 EXPORT_SYMBOL_GPL(debugfs_create_u8);
 110
 111 static int debugfs_u16_set(void *data, u64 val)
 112 {
 113         *(u16 *)data = val;
 114         return 0;
 115 }
 116 static int debugfs_u16_get(void *data, u64 *val)
 117 {
 118         *val = *(u16 *)data;
 119         return 0;
 120 }
 121 DEFINE_SIMPLE_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu\n");
 122 DEFINE_SIMPLE_ATTRIBUTE(fops_u16_ro, debugfs_u16_get, NULL, "%llu\n");
 123 DEFINE_SIMPLE_ATTRIBUTE(fops_u16_wo, NULL, debugfs_u16_set, "%llu\n");
 124
 125 /**
 126  * debugfs_create_u16 - create a debugfs file that is used to read and write an unsigned 16-bit value
 127  * @name: a pointer to a string containing the name of the file to create.
 128  * @mode: the permission that the file should have
 129  * @parent: a pointer to the parent dentry for this file.  This should be a
 130  *          directory dentry if set.  If this parameter is %NULL, then the
 131  *          file will be created in the root of the debugfs filesystem.
 132  * @value: a pointer to the variable that the file should read to and write
 133  *         from.
 134  *
 135  * This function creates a file in debugfs with the given name that
 136  * contains the value of the variable @value.  If the @mode variable is so
 137  * set, it can be read from, and written to.
 138  *
 139  * This function will return a pointer to a dentry if it succeeds.  This
 140  * pointer must be passed to the debugfs_remove() function when the file is
 141  * to be removed (no automatic cleanup happens if your module is unloaded,
 142  * you are responsible here.)  If an error occurs, %NULL will be returned.
 143  *
 144  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 145  * returned.  It is not wise to check for this value, but rather, check for
 146  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 147  * code.
 148  */
 149 struct dentry *debugfs_create_u16(const char *name, mode_t mode,
 150                                   struct dentry *parent, u16 *value)
 151 {
 152         /* if there are no write bits set, make read only */
 153         if (!(mode & S_IWUGO))
 154                 return debugfs_create_file(name, mode, parent, value, &fops_u16_ro);
 155         /* if there are no read bits set, make write only */
 156         if (!(mode & S_IRUGO))
 157                 return debugfs_create_file(name, mode, parent, value, &fops_u16_wo);
 158
 159         return debugfs_create_file(name, mode, parent, value, &fops_u16);
 160 }
 161 EXPORT_SYMBOL_GPL(debugfs_create_u16);
 162
 163 static int debugfs_u32_set(void *data, u64 val)
 164 {
 165         *(u32 *)data = val;
 166         return 0;
 167 }
 168 static int debugfs_u32_get(void *data, u64 *val)
 169 {
 170         *val = *(u32 *)data;
 171         return 0;
 172 }
 173 DEFINE_SIMPLE_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu\n");
 174 DEFINE_SIMPLE_ATTRIBUTE(fops_u32_ro, debugfs_u32_get, NULL, "%llu\n");
 175 DEFINE_SIMPLE_ATTRIBUTE(fops_u32_wo, NULL, debugfs_u32_set, "%llu\n");
 176
 177 /**
 178  * debugfs_create_u32 - create a debugfs file that is used to read and write an unsigned 32-bit value
 179  * @name: a pointer to a string containing the name of the file to create.
 180  * @mode: the permission that the file should have
 181  * @parent: a pointer to the parent dentry for this file.  This should be a
 182  *          directory dentry if set.  If this parameter is %NULL, then the
 183  *          file will be created in the root of the debugfs filesystem.
 184  * @value: a pointer to the variable that the file should read to and write
 185  *         from.
 186  *
 187  * This function creates a file in debugfs with the given name that
 188  * contains the value of the variable @value.  If the @mode variable is so
 189  * set, it can be read from, and written to.
 190  *
 191  * This function will return a pointer to a dentry if it succeeds.  This
 192  * pointer must be passed to the debugfs_remove() function when the file is
 193  * to be removed (no automatic cleanup happens if your module is unloaded,
 194  * you are responsible here.)  If an error occurs, %NULL will be returned.
 195  *
 196  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 197  * returned.  It is not wise to check for this value, but rather, check for
 198  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 199  * code.
 200  */
 201 struct dentry *debugfs_create_u32(const char *name, mode_t mode,
 202                                  struct dentry *parent, u32 *value)
 203 {
 204         /* if there are no write bits set, make read only */
 205         if (!(mode & S_IWUGO))
 206                 return debugfs_create_file(name, mode, parent, value, &fops_u32_ro);
 207         /* if there are no read bits set, make write only */
 208         if (!(mode & S_IRUGO))
 209                 return debugfs_create_file(name, mode, parent, value, &fops_u32_wo);
 210
 211         return debugfs_create_file(name, mode, parent, value, &fops_u32);
 212 }
 213 EXPORT_SYMBOL_GPL(debugfs_create_u32);
 214
 215 static int debugfs_u64_set(void *data, u64 val)
 216 {
 217         *(u64 *)data = val;
 218         return 0;
 219 }
 220
 221 static int debugfs_u64_get(void *data, u64 *val)
 222 {
 223         *val = *(u64 *)data;
 224         return 0;
 225 }
 226 DEFINE_SIMPLE_ATTRIBUTE(fops_u64, debugfs_u64_get, debugfs_u64_set, "%llu\n");
 227 DEFINE_SIMPLE_ATTRIBUTE(fops_u64_ro, debugfs_u64_get, NULL, "%llu\n");
 228 DEFINE_SIMPLE_ATTRIBUTE(fops_u64_wo, NULL, debugfs_u64_set, "%llu\n");
 229
 230 /**
 231  * debugfs_create_u64 - create a debugfs file that is used to read and write an unsigned 64-bit 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_u64(const char *name, mode_t mode,
 255                                  struct dentry *parent, u64 *value)
 256 {
 257         /* if there are no write bits set, make read only */
 258         if (!(mode & S_IWUGO))
 259                 return debugfs_create_file(name, mode, parent, value, &fops_u64_ro);
 260         /* if there are no read bits set, make write only */
 261         if (!(mode & S_IRUGO))
 262                 return debugfs_create_file(name, mode, parent, value, &fops_u64_wo);
 263
 264         return debugfs_create_file(name, mode, parent, value, &fops_u64);
 265 }
 266 EXPORT_SYMBOL_GPL(debugfs_create_u64);
 267
 268 DEFINE_SIMPLE_ATTRIBUTE(fops_x8, debugfs_u8_get, debugfs_u8_set, "0x%02llx\n");
 269 DEFINE_SIMPLE_ATTRIBUTE(fops_x8_ro, debugfs_u8_get, NULL, "0x%02llx\n");
 270 DEFINE_SIMPLE_ATTRIBUTE(fops_x8_wo, NULL, debugfs_u8_set, "0x%02llx\n");
 271
 272 DEFINE_SIMPLE_ATTRIBUTE(fops_x16, debugfs_u16_get, debugfs_u16_set, "0x%04llx\n");
 273 DEFINE_SIMPLE_ATTRIBUTE(fops_x16_ro, debugfs_u16_get, NULL, "0x%04llx\n");
 274 DEFINE_SIMPLE_ATTRIBUTE(fops_x16_wo, NULL, debugfs_u16_set, "0x%04llx\n");
 275
 276 DEFINE_SIMPLE_ATTRIBUTE(fops_x32, debugfs_u32_get, debugfs_u32_set, "0x%08llx\n");
 277 DEFINE_SIMPLE_ATTRIBUTE(fops_x32_ro, debugfs_u32_get, NULL, "0x%08llx\n");
 278 DEFINE_SIMPLE_ATTRIBUTE(fops_x32_wo, NULL, debugfs_u32_set, "0x%08llx\n");
 279
 280 DEFINE_SIMPLE_ATTRIBUTE(fops_x64, debugfs_u64_get, debugfs_u64_set, "0x%016llx\n");
 281
 282 /*
 283  * debugfs_create_x{8,16,32,64} - create a debugfs file that is used to read and write an unsigned {8,16,32,64}-bit value
 284  *
 285  * These functions are exactly the same as the above functions (but use a hex
 286  * output for the decimal challenged). For details look at the above unsigned
 287  * decimal functions.
 288  */
 289
 290 /**
 291  * debugfs_create_x8 - create a debugfs file that is used to read and write an unsigned 8-bit value
 292  * @name: a pointer to a string containing the name of the file to create.
 293  * @mode: the permission that the file should have
 294  * @parent: a pointer to the parent dentry for this file.  This should be a
 295  *          directory dentry if set.  If this parameter is %NULL, then the
 296  *          file will be created in the root of the debugfs filesystem.
 297  * @value: a pointer to the variable that the file should read to and write
 298  *         from.
 299  */
 300 struct dentry *debugfs_create_x8(const char *name, mode_t mode,
 301                                  struct dentry *parent, u8 *value)
 302 {
 303         /* if there are no write bits set, make read only */
 304         if (!(mode & S_IWUGO))
 305                 return debugfs_create_file(name, mode, parent, value, &fops_x8_ro);
 306         /* if there are no read bits set, make write only */
 307         if (!(mode & S_IRUGO))
 308                 return debugfs_create_file(name, mode, parent, value, &fops_x8_wo);
 309
 310         return debugfs_create_file(name, mode, parent, value, &fops_x8);
 311 }
 312 EXPORT_SYMBOL_GPL(debugfs_create_x8);
 313
 314 /**
 315  * debugfs_create_x16 - create a debugfs file that is used to read and write an unsigned 16-bit value
 316  * @name: a pointer to a string containing the name of the file to create.
 317  * @mode: the permission that the file should have
 318  * @parent: a pointer to the parent dentry for this file.  This should be a
 319  *          directory dentry if set.  If this parameter is %NULL, then the
 320  *          file will be created in the root of the debugfs filesystem.
 321  * @value: a pointer to the variable that the file should read to and write
 322  *         from.
 323  */
 324 struct dentry *debugfs_create_x16(const char *name, mode_t mode,
 325                                  struct dentry *parent, u16 *value)
 326 {
 327         /* if there are no write bits set, make read only */
 328         if (!(mode & S_IWUGO))
 329                 return debugfs_create_file(name, mode, parent, value, &fops_x16_ro);
 330         /* if there are no read bits set, make write only */
 331         if (!(mode & S_IRUGO))
 332                 return debugfs_create_file(name, mode, parent, value, &fops_x16_wo);
 333
 334         return debugfs_create_file(name, mode, parent, value, &fops_x16);
 335 }
 336 EXPORT_SYMBOL_GPL(debugfs_create_x16);
 337
 338 /**
 339  * debugfs_create_x32 - create a debugfs file that is used to read and write an unsigned 32-bit value
 340  * @name: a pointer to a string containing the name of the file to create.
 341  * @mode: the permission that the file should have
 342  * @parent: a pointer to the parent dentry for this file.  This should be a
 343  *          directory dentry if set.  If this parameter is %NULL, then the
 344  *          file will be created in the root of the debugfs filesystem.
 345  * @value: a pointer to the variable that the file should read to and write
 346  *         from.
 347  */
 348 struct dentry *debugfs_create_x32(const char *name, mode_t mode,
 349                                  struct dentry *parent, u32 *value)
 350 {
 351         /* if there are no write bits set, make read only */
 352         if (!(mode & S_IWUGO))
 353                 return debugfs_create_file(name, mode, parent, value, &fops_x32_ro);
 354         /* if there are no read bits set, make write only */
 355         if (!(mode & S_IRUGO))
 356                 return debugfs_create_file(name, mode, parent, value, &fops_x32_wo);
 357
 358         return debugfs_create_file(name, mode, parent, value, &fops_x32);
 359 }
 360 EXPORT_SYMBOL_GPL(debugfs_create_x32);
 361
 362 /**
 363  * debugfs_create_x64 - create a debugfs file that is used to read and write an unsigned 64-bit value
 364  * @name: a pointer to a string containing the name of the file to create.
 365  * @mode: the permission that the file should have
 366  * @parent: a pointer to the parent dentry for this file.  This should be a
 367  *          directory dentry if set.  If this parameter is %NULL, then the
 368  *          file will be created in the root of the debugfs filesystem.
 369  * @value: a pointer to the variable that the file should read to and write
 370  *         from.
 371  */
 372 struct dentry *debugfs_create_x64(const char *name, mode_t mode,
 373                                  struct dentry *parent, u64 *value)
 374 {
 375         return debugfs_create_file(name, mode, parent, value, &fops_x64);
 376 }
 377 EXPORT_SYMBOL_GPL(debugfs_create_x64);
 378
 379
 380 static int debugfs_size_t_set(void *data, u64 val)
 381 {
 382         *(size_t *)data = val;
 383         return 0;
 384 }
 385 static int debugfs_size_t_get(void *data, u64 *val)
 386 {
 387         *val = *(size_t *)data;
 388         return 0;
 389 }
 390 DEFINE_SIMPLE_ATTRIBUTE(fops_size_t, debugfs_size_t_get, debugfs_size_t_set,
 391                         "%llu\n");      /* %llu and %zu are more or less the same */
 392
 393 /**
 394  * debugfs_create_size_t - create a debugfs file that is used to read and write an size_t value
 395  * @name: a pointer to a string containing the name of the file to create.
 396  * @mode: the permission that the file should have
 397  * @parent: a pointer to the parent dentry for this file.  This should be a
 398  *          directory dentry if set.  If this parameter is %NULL, then the
 399  *          file will be created in the root of the debugfs filesystem.
 400  * @value: a pointer to the variable that the file should read to and write
 401  *         from.
 402  */
 403 struct dentry *debugfs_create_size_t(const char *name, mode_t mode,
 404                                      struct dentry *parent, size_t *value)
 405 {
 406         return debugfs_create_file(name, mode, parent, value, &fops_size_t);
 407 }
 408 EXPORT_SYMBOL_GPL(debugfs_create_size_t);
 409
 410
 411 static ssize_t read_file_bool(struct file *file, char __user *user_buf,
 412                               size_t count, loff_t *ppos)
 413 {
 414         char buf[3];
 415         u32 *val = file->private_data;
 416
 417         if (*val)
 418                 buf[0] = 'Y';
 419         else
 420                 buf[0] = 'N';
 421         buf[1] = '\n';
 422         buf[2] = 0x00;
 423         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
 424 }
 425
 426 static ssize_t write_file_bool(struct file *file, const char __user *user_buf,
 427                                size_t count, loff_t *ppos)
 428 {
 429         char buf[32];
 430         int buf_size;
 431         u32 *val = file->private_data;
 432
 433         buf_size = min(count, (sizeof(buf)-1));
 434         if (copy_from_user(buf, user_buf, buf_size))
 435                 return -EFAULT;
 436
 437         switch (buf[0]) {
 438         case 'y':
 439         case 'Y':
 440         case '1':
 441                 *val = 1;
 442                 break;
 443         case 'n':
 444         case 'N':
 445         case '0':
 446                 *val = 0;
 447                 break;
 448         }
 449
 450         return count;
 451 }
 452
 453 static const struct file_operations fops_bool = {
 454         .read =         read_file_bool,
 455         .write =        write_file_bool,
 456         .open =         default_open,
 457 };
 458
 459 /**
 460  * debugfs_create_bool - create a debugfs file that is used to read and write a boolean value
 461  * @name: a pointer to a string containing the name of the file to create.
 462  * @mode: the permission that the file should have
 463  * @parent: a pointer to the parent dentry for this file.  This should be a
 464  *          directory dentry if set.  If this parameter is %NULL, then the
 465  *          file will be created in the root of the debugfs filesystem.
 466  * @value: a pointer to the variable that the file should read to and write
 467  *         from.
 468  *
 469  * This function creates a file in debugfs with the given name that
 470  * contains the value of the variable @value.  If the @mode variable is so
 471  * set, it can be read from, and written to.
 472  *
 473  * This function will return a pointer to a dentry if it succeeds.  This
 474  * pointer must be passed to the debugfs_remove() function when the file is
 475  * to be removed (no automatic cleanup happens if your module is unloaded,
 476  * you are responsible here.)  If an error occurs, %NULL will be returned.
 477  *
 478  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 479  * returned.  It is not wise to check for this value, but rather, check for
 480  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 481  * code.
 482  */
 483 struct dentry *debugfs_create_bool(const char *name, mode_t mode,
 484                                    struct dentry *parent, u32 *value)
 485 {
 486         return debugfs_create_file(name, mode, parent, value, &fops_bool);
 487 }
 488 EXPORT_SYMBOL_GPL(debugfs_create_bool);
 489
 490 static ssize_t read_file_blob(struct file *file, char __user *user_buf,
 491                               size_t count, loff_t *ppos)
 492 {
 493         struct debugfs_blob_wrapper *blob = file->private_data;
 494         return simple_read_from_buffer(user_buf, count, ppos, blob->data,
 495                         blob->size);
 496 }
 497
 498 static const struct file_operations fops_blob = {
 499         .read =         read_file_blob,
 500         .open =         default_open,
 501 };
 502
 503 /**
 504  * debugfs_create_blob - create a debugfs file that is used to read a binary blob
 505  * @name: a pointer to a string containing the name of the file to create.
 506  * @mode: the permission that the file should have
 507  * @parent: a pointer to the parent dentry for this file.  This should be a
 508  *          directory dentry if set.  If this parameter is %NULL, then the
 509  *          file will be created in the root of the debugfs filesystem.
 510  * @blob: a pointer to a struct debugfs_blob_wrapper which contains a pointer
 511  *        to the blob data and the size of the data.
 512  *
 513  * This function creates a file in debugfs with the given name that exports
 514  * @blob->data as a binary blob. If the @mode variable is so set it can be
 515  * read from. Writing is not supported.
 516  *
 517  * This function will return a pointer to a dentry if it succeeds.  This
 518  * pointer must be passed to the debugfs_remove() function when the file is
 519  * to be removed (no automatic cleanup happens if your module is unloaded,
 520  * you are responsible here.)  If an error occurs, %NULL will be returned.
 521  *
 522  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 523  * returned.  It is not wise to check for this value, but rather, check for
 524  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 525  * code.
 526  */
 527 struct dentry *debugfs_create_blob(const char *name, mode_t mode,
 528                                    struct dentry *parent,
 529                                    struct debugfs_blob_wrapper *blob)
 530 {
 531         return debugfs_create_file(name, mode, parent, blob, &fops_blob);
 532 }
 533 EXPORT_SYMBOL_GPL(debugfs_create_blob);