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/config.h>
  17 #include <linux/module.h>
  18 #include <linux/fs.h>
  19 #include <linux/pagemap.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->u.generic_ip)
  37                 file->private_data = inode->u.generic_ip;
  38
  39         return 0;
  40 }
  41
  42 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_u8_set(void *data, u64 val)
  49 {
  50         *(u8 *)data = val;
  51 }
  52 static u64 debugfs_u8_get(void *data)
  53 {
  54         return *(u8 *)data;
  55 }
  56 DEFINE_SIMPLE_ATTRIBUTE(fops_u8, debugfs_u8_get, debugfs_u8_set, "%llu\n");
  57
  58 /**
  59  * debugfs_create_u8 - create a file in the debugfs filesystem that is used to read and write an unsigned 8 bit value.
  60  *
  61  * @name: a pointer to a string containing the name of the file to create.
  62  * @mode: the permission that the file should have
  63  * @parent: a pointer to the parent dentry for this file.  This should be a
  64  *          directory dentry if set.  If this paramater is NULL, then the
  65  *          file will be created in the root of the debugfs filesystem.
  66  * @value: a pointer to the variable that the file should read to and write
  67  *         from.
  68  *
  69  * This function creates a file in debugfs with the given name that
  70  * contains the value of the variable @value.  If the @mode variable is so
  71  * set, it can be read from, and written to.
  72  *
  73  * This function will return a pointer to a dentry if it succeeds.  This
  74  * pointer must be passed to the debugfs_remove() function when the file is
  75  * to be removed (no automatic cleanup happens if your module is unloaded,
  76  * you are responsible here.)  If an error occurs, NULL will be returned.
  77  *
  78  * If debugfs is not enabled in the kernel, the value -ENODEV will be
  79  * returned.  It is not wise to check for this value, but rather, check for
  80  * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
  81  * code.
  82  */
  83 struct dentry *debugfs_create_u8(const char *name, mode_t mode,
  84                                  struct dentry *parent, u8 *value)
  85 {
  86         return debugfs_create_file(name, mode, parent, value, &fops_u8);
  87 }
  88 EXPORT_SYMBOL_GPL(debugfs_create_u8);
  89
  90 static void debugfs_u16_set(void *data, u64 val)
  91 {
  92         *(u16 *)data = val;
  93 }
  94 static u64 debugfs_u16_get(void *data)
  95 {
  96         return *(u16 *)data;
  97 }
  98 DEFINE_SIMPLE_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu\n");
  99
 100 /**
 101  * debugfs_create_u16 - create a file in the debugfs filesystem that is used to read and write an unsigned 16 bit value.
 102  *
 103  * @name: a pointer to a string containing the name of the file to create.
 104  * @mode: the permission that the file should have
 105  * @parent: a pointer to the parent dentry for this file.  This should be a
 106  *          directory dentry if set.  If this paramater is NULL, then the
 107  *          file will be created in the root of the debugfs filesystem.
 108  * @value: a pointer to the variable that the file should read to and write
 109  *         from.
 110  *
 111  * This function creates a file in debugfs with the given name that
 112  * contains the value of the variable @value.  If the @mode variable is so
 113  * set, it can be read from, and written to.
 114  *
 115  * This function will return a pointer to a dentry if it succeeds.  This
 116  * pointer must be passed to the debugfs_remove() function when the file is
 117  * to be removed (no automatic cleanup happens if your module is unloaded,
 118  * you are responsible here.)  If an error occurs, NULL will be returned.
 119  *
 120  * If debugfs is not enabled in the kernel, the value -ENODEV will be
 121  * returned.  It is not wise to check for this value, but rather, check for
 122  * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
 123  * code.
 124  */
 125 struct dentry *debugfs_create_u16(const char *name, mode_t mode,
 126                                   struct dentry *parent, u16 *value)
 127 {
 128         return debugfs_create_file(name, mode, parent, value, &fops_u16);
 129 }
 130 EXPORT_SYMBOL_GPL(debugfs_create_u16);
 131
 132 static void debugfs_u32_set(void *data, u64 val)
 133 {
 134         *(u32 *)data = val;
 135 }
 136 static u64 debugfs_u32_get(void *data)
 137 {
 138         return *(u32 *)data;
 139 }
 140 DEFINE_SIMPLE_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu\n");
 141
 142 /**
 143  * debugfs_create_u32 - create a file in the debugfs filesystem that is used to read and write an unsigned 32 bit value.
 144  *
 145  * @name: a pointer to a string containing the name of the file to create.
 146  * @mode: the permission that the file should have
 147  * @parent: a pointer to the parent dentry for this file.  This should be a
 148  *          directory dentry if set.  If this paramater is NULL, then the
 149  *          file will be created in the root of the debugfs filesystem.
 150  * @value: a pointer to the variable that the file should read to and write
 151  *         from.
 152  *
 153  * This function creates a file in debugfs with the given name that
 154  * contains the value of the variable @value.  If the @mode variable is so
 155  * set, it can be read from, and written to.
 156  *
 157  * This function will return a pointer to a dentry if it succeeds.  This
 158  * pointer must be passed to the debugfs_remove() function when the file is
 159  * to be removed (no automatic cleanup happens if your module is unloaded,
 160  * you are responsible here.)  If an error occurs, NULL will be returned.
 161  *
 162  * If debugfs is not enabled in the kernel, the value -ENODEV will be
 163  * returned.  It is not wise to check for this value, but rather, check for
 164  * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
 165  * code.
 166  */
 167 struct dentry *debugfs_create_u32(const char *name, mode_t mode,
 168                                  struct dentry *parent, u32 *value)
 169 {
 170         return debugfs_create_file(name, mode, parent, value, &fops_u32);
 171 }
 172 EXPORT_SYMBOL_GPL(debugfs_create_u32);
 173
 174 static ssize_t read_file_bool(struct file *file, char __user *user_buf,
 175                               size_t count, loff_t *ppos)
 176 {
 177         char buf[3];
 178         u32 *val = file->private_data;
 179
 180         if (*val)
 181                 buf[0] = 'Y';
 182         else
 183                 buf[0] = 'N';
 184         buf[1] = '\n';
 185         buf[2] = 0x00;
 186         return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
 187 }
 188
 189 static ssize_t write_file_bool(struct file *file, const char __user *user_buf,
 190                                size_t count, loff_t *ppos)
 191 {
 192         char buf[32];
 193         int buf_size;
 194         u32 *val = file->private_data;
 195
 196         buf_size = min(count, (sizeof(buf)-1));
 197         if (copy_from_user(buf, user_buf, buf_size))
 198                 return -EFAULT;
 199
 200         switch (buf[0]) {
 201         case 'y':
 202         case 'Y':
 203         case '1':
 204                 *val = 1;
 205                 break;
 206         case 'n':
 207         case 'N':
 208         case '0':
 209                 *val = 0;
 210                 break;
 211         }
 212
 213         return count;
 214 }
 215
 216 static struct file_operations fops_bool = {
 217         .read =         read_file_bool,
 218         .write =        write_file_bool,
 219         .open =         default_open,
 220 };
 221
 222 /**
 223  * debugfs_create_bool - create a file in the debugfs filesystem that is used to read and write a boolean value.
 224  *
 225  * @name: a pointer to a string containing the name of the file to create.
 226  * @mode: the permission that the file should have
 227  * @parent: a pointer to the parent dentry for this file.  This should be a
 228  *          directory dentry if set.  If this paramater is NULL, then the
 229  *          file will be created in the root of the debugfs filesystem.
 230  * @value: a pointer to the variable that the file should read to and write
 231  *         from.
 232  *
 233  * This function creates a file in debugfs with the given name that
 234  * contains the value of the variable @value.  If the @mode variable is so
 235  * set, it can be read from, and written to.
 236  *
 237  * This function will return a pointer to a dentry if it succeeds.  This
 238  * pointer must be passed to the debugfs_remove() function when the file is
 239  * to be removed (no automatic cleanup happens if your module is unloaded,
 240  * you are responsible here.)  If an error occurs, NULL will be returned.
 241  *
 242  * If debugfs is not enabled in the kernel, the value -ENODEV will be
 243  * returned.  It is not wise to check for this value, but rather, check for
 244  * NULL or !NULL instead as to eliminate the need for #ifdef in the calling
 245  * code.
 246  */
 247 struct dentry *debugfs_create_bool(const char *name, mode_t mode,
 248                                    struct dentry *parent, u32 *value)
 249 {
 250         return debugfs_create_file(name, mode, parent, value, &fops_bool);
 251 }
 252 EXPORT_SYMBOL_GPL(debugfs_create_bool);
 253