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->u.generic_ip)
  36                 file->private_data = inode->u.generic_ip;
  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 file in the debugfs filesystem that is used to read and write an unsigned 8 bit value.
  59  *
  60  * @name: a pointer to a string containing the name of the file to create.
  61  * @mode: the permission that the file should have
  62  * @parent: a pointer to the parent dentry for this file.  This should be a
  63  *          directory dentry if set.  If this paramater is NULL, then the
  64  *          file will be created in the root of the debugfs filesystem.
  65  * @value: a pointer to the variable that the file should read to and write
  66  *         from.
  67  *
  68  * This function creates a file in debugfs with the given name that
  69  * contains the value of the variable @value.  If the @mode variable is so
  70  * set, it can be read from, and written to.
  71  *
  72  * This function will return a pointer to a dentry if it succeeds.  This
  73  * pointer must be passed to the debugfs_remove() function when the file is
  74  * to be removed (no automatic cleanup happens if your module is unloaded,
  75  * you are responsible here.)  If an error occurs, NULL will be returned.
  76  *
  77  * If debugfs is not enabled in the kernel, the value -ENODEV will be
  78  * returned.  It is not wise to check for this value, but rather, check for
  79  * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
  80  * code.
  81  */
  82 struct dentry *debugfs_create_u8(const char *name, mode_t mode,
  83                                  struct dentry *parent, u8 *value)
  84 {
  85         return debugfs_create_file(name, mode, parent, value, &fops_u8);
  86 }
  87 EXPORT_SYMBOL_GPL(debugfs_create_u8);
  88
  89 static void debugfs_u16_set(void *data, u64 val)
  90 {
  91         *(u16 *)data = val;
  92 }
  93 static u64 debugfs_u16_get(void *data)
  94 {
  95         return *(u16 *)data;
  96 }
  97 DEFINE_SIMPLE_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu\n");
  98
  99 /**
 100  * debugfs_create_u16 - create a file in the debugfs filesystem that is used to read and write an unsigned 16 bit value.
 101  *
 102  * @name: a pointer to a string containing the name of the file to create.
 103  * @mode: the permission that the file should have
 104  * @parent: a pointer to the parent dentry for this file.  This should be a
 105  *          directory dentry if set.  If this paramater is NULL, then the
 106  *          file will be created in the root of the debugfs filesystem.
 107  * @value: a pointer to the variable that the file should read to and write
 108  *         from.
 109  *
 110  * This function creates a file in debugfs with the given name that
 111  * contains the value of the variable @value.  If the @mode variable is so
 112  * set, it can be read from, and written to.
 113  *
 114  * This function will return a pointer to a dentry if it succeeds.  This
 115  * pointer must be passed to the debugfs_remove() function when the file is
 116  * to be removed (no automatic cleanup happens if your module is unloaded,
 117  * you are responsible here.)  If an error occurs, NULL will be returned.
 118  *
 119  * If debugfs is not enabled in the kernel, the value -ENODEV will be
 120  * returned.  It is not wise to check for this value, but rather, check for
 121  * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
 122  * code.
 123  */
 124 struct dentry *debugfs_create_u16(const char *name, mode_t mode,
 125                                   struct dentry *parent, u16 *value)
 126 {
 127         return debugfs_create_file(name, mode, parent, value, &fops_u16);
 128 }
 129 EXPORT_SYMBOL_GPL(debugfs_create_u16);
 130
 131 static void debugfs_u32_set(void *data, u64 val)
 132 {
 133         *(u32 *)data = val;
 134 }
 135 static u64 debugfs_u32_get(void *data)
 136 {
 137         return *(u32 *)data;
 138 }
 139 DEFINE_SIMPLE_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu\n");
 140
 141 /**
 142  * debugfs_create_u32 - create a file in the debugfs filesystem that is used to read and write an unsigned 32 bit value.
 143  *
 144  * @name: a pointer to a string containing the name of the file to create.
 145  * @mode: the permission that the file should have
 146  * @parent: a pointer to the parent dentry for this file.  This should be a
 147  *          directory dentry if set.  If this paramater is NULL, then the
 148  *          file will be created in the root of the debugfs filesystem.
 149  * @value: a pointer to the variable that the file should read to and write
 150  *         from.
 151  *
 152  * This function creates a file in debugfs with the given name that
 153  * contains the value of the variable @value.  If the @mode variable is so
 154  * set, it can be read from, and written to.
 155  *
 156  * This function will return a pointer to a dentry if it succeeds.  This
 157  * pointer must be passed to the debugfs_remove() function when the file is
 158  * to be removed (no automatic cleanup happens if your module is unloaded,
 159  * you are responsible here.)  If an error occurs, NULL will be returned.
 160  *
 161  * If debugfs is not enabled in the kernel, the value -ENODEV will be
 162  * returned.  It is not wise to check for this value, but rather, check for
 163  * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
 164  * code.
 165  */
 166 struct dentry *debugfs_create_u32(const char *name, mode_t mode,
 167                                  struct dentry *parent, u32 *value)
 168 {
 169         return debugfs_create_file(name, mode, parent, value, &fops_u32);
 170 }
 171 EXPORT_SYMBOL_GPL(debugfs_create_u32);
 172
 173 static ssize_t read_file_bool(struct file *file, char __user *user_buf,
 174                               size_t count, loff_t *ppos)
 175 {
 176         char buf[3];
 177         u32 *val = file->private_data;
 178
 179         if (*val)
 180                 buf[0] = 'Y';
 181         else
 182                 buf[0] = 'N';
 183         buf[1] = '\n';
 184         buf[2] = 0x00;
 185         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
 186 }
 187
 188 static ssize_t write_file_bool(struct file *file, const char __user *user_buf,
 189                                size_t count, loff_t *ppos)
 190 {
 191         char buf[32];
 192         int buf_size;
 193         u32 *val = file->private_data;
 194
 195         buf_size = min(count, (sizeof(buf)-1));
 196         if (copy_from_user(buf, user_buf, buf_size))
 197                 return -EFAULT;
 198
 199         switch (buf[0]) {
 200         case 'y':
 201         case 'Y':
 202         case '1':
 203                 *val = 1;
 204                 break;
 205         case 'n':
 206         case 'N':
 207         case '0':
 208                 *val = 0;
 209                 break;
 210         }
 211
 212         return count;
 213 }
 214
 215 static const struct file_operations fops_bool = {
 216         .read =         read_file_bool,
 217         .write =        write_file_bool,
 218         .open =         default_open,
 219 };
 220
 221 /**
 222  * debugfs_create_bool - create a file in the debugfs filesystem that is used to read and write a boolean value.
 223  *
 224  * @name: a pointer to a string containing the name of the file to create.
 225  * @mode: the permission that the file should have
 226  * @parent: a pointer to the parent dentry for this file.  This should be a
 227  *          directory dentry if set.  If this paramater is NULL, then the
 228  *          file will be created in the root of the debugfs filesystem.
 229  * @value: a pointer to the variable that the file should read to and write
 230  *         from.
 231  *
 232  * This function creates a file in debugfs with the given name that
 233  * contains the value of the variable @value.  If the @mode variable is so
 234  * set, it can be read from, and written to.
 235  *
 236  * This function will return a pointer to a dentry if it succeeds.  This
 237  * pointer must be passed to the debugfs_remove() function when the file is
 238  * to be removed (no automatic cleanup happens if your module is unloaded,
 239  * you are responsible here.)  If an error occurs, NULL will be returned.
 240  *
 241  * If debugfs is not enabled in the kernel, the value -ENODEV will be
 242  * returned.  It is not wise to check for this value, but rather, check for
 243  * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
 244  * code.
 245  */
 246 struct dentry *debugfs_create_bool(const char *name, mode_t mode,
 247                                    struct dentry *parent, u32 *value)
 248 {
 249         return debugfs_create_file(name, mode, parent, value, &fops_bool);
 250 }
 251 EXPORT_SYMBOL_GPL(debugfs_create_bool);
 252
 253 static ssize_t read_file_blob(struct file *file, char __user *user_buf,
 254                               size_t count, loff_t *ppos)
 255 {
 256         struct debugfs_blob_wrapper *blob = file->private_data;
 257         return simple_read_from_buffer(user_buf, count, ppos, blob->data,
 258                         blob->size);
 259 }
 260
 261 static struct file_operations fops_blob = {
 262         .read =         read_file_blob,
 263         .open =         default_open,
 264 };
 265
 266 /**
 267  * debugfs_create_blob - create a file in the debugfs filesystem that is
 268  * used to read and write a binary blob.
 269  *
 270  * @name: a pointer to a string containing the name of the file to create.
 271  * @mode: the permission that the file should have
 272  * @parent: a pointer to the parent dentry for this file.  This should be a
 273  *          directory dentry if set.  If this paramater is NULL, then the
 274  *          file will be created in the root of the debugfs filesystem.
 275  * @blob: a pointer to a struct debugfs_blob_wrapper which contains a pointer
 276  *        to the blob data and the size of the data.
 277  *
 278  * This function creates a file in debugfs with the given name that exports
 279  * @blob->data as a binary blob. If the @mode variable is so set it can be
 280  * read from. Writing is not supported.
 281  *
 282  * This function will return a pointer to a dentry if it succeeds.  This
 283  * pointer must be passed to the debugfs_remove() function when the file is
 284  * to be removed (no automatic cleanup happens if your module is unloaded,
 285  * you are responsible here.)  If an error occurs, NULL will be returned.
 286  *
 287  * If debugfs is not enabled in the kernel, the value -ENODEV will be
 288  * returned.  It is not wise to check for this value, but rather, check for
 289  * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
 290  * code.
 291  */
 292 struct dentry *debugfs_create_blob(const char *name, mode_t mode,
 293                                    struct dentry *parent,
 294                                    struct debugfs_blob_wrapper *blob)
 295 {
 296         return debugfs_create_file(name, mode, parent, blob, &fops_blob);
 297 }
 298 EXPORT_SYMBOL_GPL(debugfs_create_blob);