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 /*
 281  * debugfs_create_x{8,16,32} - create a debugfs file that is used to read and write an unsigned {8,16,32}-bit value
 282  *
 283  * These functions are exactly the same as the above functions (but use a hex
 284  * output for the decimal challenged). For details look at the above unsigned
 285  * decimal functions.
 286  */
 287
 288 /**
 289  * debugfs_create_x8 - create a debugfs file that is used to read and write an unsigned 8-bit value
 290  * @name: a pointer to a string containing the name of the file to create.
 291  * @mode: the permission that the file should have
 292  * @parent: a pointer to the parent dentry for this file.  This should be a
 293  *          directory dentry if set.  If this parameter is %NULL, then the
 294  *          file will be created in the root of the debugfs filesystem.
 295  * @value: a pointer to the variable that the file should read to and write
 296  *         from.
 297  */
 298 struct dentry *debugfs_create_x8(const char *name, mode_t mode,
 299                                  struct dentry *parent, u8 *value)
 300 {
 301         /* if there are no write bits set, make read only */
 302         if (!(mode & S_IWUGO))
 303                 return debugfs_create_file(name, mode, parent, value, &fops_x8_ro);
 304         /* if there are no read bits set, make write only */
 305         if (!(mode & S_IRUGO))
 306                 return debugfs_create_file(name, mode, parent, value, &fops_x8_wo);
 307
 308         return debugfs_create_file(name, mode, parent, value, &fops_x8);
 309 }
 310 EXPORT_SYMBOL_GPL(debugfs_create_x8);
 311
 312 /**
 313  * debugfs_create_x16 - create a debugfs file that is used to read and write an unsigned 16-bit value
 314  * @name: a pointer to a string containing the name of the file to create.
 315  * @mode: the permission that the file should have
 316  * @parent: a pointer to the parent dentry for this file.  This should be a
 317  *          directory dentry if set.  If this parameter is %NULL, then the
 318  *          file will be created in the root of the debugfs filesystem.
 319  * @value: a pointer to the variable that the file should read to and write
 320  *         from.
 321  */
 322 struct dentry *debugfs_create_x16(const char *name, mode_t mode,
 323                                  struct dentry *parent, u16 *value)
 324 {
 325         /* if there are no write bits set, make read only */
 326         if (!(mode & S_IWUGO))
 327                 return debugfs_create_file(name, mode, parent, value, &fops_x16_ro);
 328         /* if there are no read bits set, make write only */
 329         if (!(mode & S_IRUGO))
 330                 return debugfs_create_file(name, mode, parent, value, &fops_x16_wo);
 331
 332         return debugfs_create_file(name, mode, parent, value, &fops_x16);
 333 }
 334 EXPORT_SYMBOL_GPL(debugfs_create_x16);
 335
 336 /**
 337  * debugfs_create_x32 - create a debugfs file that is used to read and write an unsigned 32-bit value
 338  * @name: a pointer to a string containing the name of the file to create.
 339  * @mode: the permission that the file should have
 340  * @parent: a pointer to the parent dentry for this file.  This should be a
 341  *          directory dentry if set.  If this parameter is %NULL, then the
 342  *          file will be created in the root of the debugfs filesystem.
 343  * @value: a pointer to the variable that the file should read to and write
 344  *         from.
 345  */
 346 struct dentry *debugfs_create_x32(const char *name, mode_t mode,
 347                                  struct dentry *parent, u32 *value)
 348 {
 349         /* if there are no write bits set, make read only */
 350         if (!(mode & S_IWUGO))
 351                 return debugfs_create_file(name, mode, parent, value, &fops_x32_ro);
 352         /* if there are no read bits set, make write only */
 353         if (!(mode & S_IRUGO))
 354                 return debugfs_create_file(name, mode, parent, value, &fops_x32_wo);
 355
 356         return debugfs_create_file(name, mode, parent, value, &fops_x32);
 357 }
 358 EXPORT_SYMBOL_GPL(debugfs_create_x32);
 359
 360
 361 static int debugfs_size_t_set(void *data, u64 val)
 362 {
 363         *(size_t *)data = val;
 364         return 0;
 365 }
 366 static int debugfs_size_t_get(void *data, u64 *val)
 367 {
 368         *val = *(size_t *)data;
 369         return 0;
 370 }
 371 DEFINE_SIMPLE_ATTRIBUTE(fops_size_t, debugfs_size_t_get, debugfs_size_t_set,
 372                         "%llu\n");      /* %llu and %zu are more or less the same */
 373
 374 /**
 375  * debugfs_create_size_t - create a debugfs file that is used to read and write an size_t value
 376  * @name: a pointer to a string containing the name of the file to create.
 377  * @mode: the permission that the file should have
 378  * @parent: a pointer to the parent dentry for this file.  This should be a
 379  *          directory dentry if set.  If this parameter is %NULL, then the
 380  *          file will be created in the root of the debugfs filesystem.
 381  * @value: a pointer to the variable that the file should read to and write
 382  *         from.
 383  */
 384 struct dentry *debugfs_create_size_t(const char *name, mode_t mode,
 385                                      struct dentry *parent, size_t *value)
 386 {
 387         return debugfs_create_file(name, mode, parent, value, &fops_size_t);
 388 }
 389 EXPORT_SYMBOL_GPL(debugfs_create_size_t);
 390
 391
 392 static ssize_t read_file_bool(struct file *file, char __user *user_buf,
 393                               size_t count, loff_t *ppos)
 394 {
 395         char buf[3];
 396         u32 *val = file->private_data;
 397
 398         if (*val)
 399                 buf[0] = 'Y';
 400         else
 401                 buf[0] = 'N';
 402         buf[1] = '\n';
 403         buf[2] = 0x00;
 404         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
 405 }
 406
 407 static ssize_t write_file_bool(struct file *file, const char __user *user_buf,
 408                                size_t count, loff_t *ppos)
 409 {
 410         char buf[32];
 411         int buf_size;
 412         u32 *val = file->private_data;
 413
 414         buf_size = min(count, (sizeof(buf)-1));
 415         if (copy_from_user(buf, user_buf, buf_size))
 416                 return -EFAULT;
 417
 418         switch (buf[0]) {
 419         case 'y':
 420         case 'Y':
 421         case '1':
 422                 *val = 1;
 423                 break;
 424         case 'n':
 425         case 'N':
 426         case '0':
 427                 *val = 0;
 428                 break;
 429         }
 430
 431         return count;
 432 }
 433
 434 static const struct file_operations fops_bool = {
 435         .read =         read_file_bool,
 436         .write =        write_file_bool,
 437         .open =         default_open,
 438 };
 439
 440 /**
 441  * debugfs_create_bool - create a debugfs file that is used to read and write a boolean value
 442  * @name: a pointer to a string containing the name of the file to create.
 443  * @mode: the permission that the file should have
 444  * @parent: a pointer to the parent dentry for this file.  This should be a
 445  *          directory dentry if set.  If this parameter is %NULL, then the
 446  *          file will be created in the root of the debugfs filesystem.
 447  * @value: a pointer to the variable that the file should read to and write
 448  *         from.
 449  *
 450  * This function creates a file in debugfs with the given name that
 451  * contains the value of the variable @value.  If the @mode variable is so
 452  * set, it can be read from, and written to.
 453  *
 454  * This function will return a pointer to a dentry if it succeeds.  This
 455  * pointer must be passed to the debugfs_remove() function when the file is
 456  * to be removed (no automatic cleanup happens if your module is unloaded,
 457  * you are responsible here.)  If an error occurs, %NULL will be returned.
 458  *
 459  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 460  * returned.  It is not wise to check for this value, but rather, check for
 461  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 462  * code.
 463  */
 464 struct dentry *debugfs_create_bool(const char *name, mode_t mode,
 465                                    struct dentry *parent, u32 *value)
 466 {
 467         return debugfs_create_file(name, mode, parent, value, &fops_bool);
 468 }
 469 EXPORT_SYMBOL_GPL(debugfs_create_bool);
 470
 471 static ssize_t read_file_blob(struct file *file, char __user *user_buf,
 472                               size_t count, loff_t *ppos)
 473 {
 474         struct debugfs_blob_wrapper *blob = file->private_data;
 475         return simple_read_from_buffer(user_buf, count, ppos, blob->data,
 476                         blob->size);
 477 }
 478
 479 static const struct file_operations fops_blob = {
 480         .read =         read_file_blob,
 481         .open =         default_open,
 482 };
 483
 484 /**
 485  * debugfs_create_blob - create a debugfs file that is used to read a binary blob
 486  * @name: a pointer to a string containing the name of the file to create.
 487  * @mode: the permission that the file should have
 488  * @parent: a pointer to the parent dentry for this file.  This should be a
 489  *          directory dentry if set.  If this parameter is %NULL, then the
 490  *          file will be created in the root of the debugfs filesystem.
 491  * @blob: a pointer to a struct debugfs_blob_wrapper which contains a pointer
 492  *        to the blob data and the size of the data.
 493  *
 494  * This function creates a file in debugfs with the given name that exports
 495  * @blob->data as a binary blob. If the @mode variable is so set it can be
 496  * read from. Writing is not supported.
 497  *
 498  * This function will return a pointer to a dentry if it succeeds.  This
 499  * pointer must be passed to the debugfs_remove() function when the file is
 500  * to be removed (no automatic cleanup happens if your module is unloaded,
 501  * you are responsible here.)  If an error occurs, %NULL will be returned.
 502  *
 503  * If debugfs is not enabled in the kernel, the value -%ENODEV will be
 504  * returned.  It is not wise to check for this value, but rather, check for
 505  * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
 506  * code.
 507  */
 508 struct dentry *debugfs_create_blob(const char *name, mode_t mode,
 509                                    struct dentry *parent,
 510                                    struct debugfs_blob_wrapper *blob)
 511 {
 512         return debugfs_create_file(name, mode, parent, blob, &fops_blob);
 513 }
 514 EXPORT_SYMBOL_GPL(debugfs_create_blob);