/*
   *  file.c - part of debugfs, a tiny little debug file system
   *
   *  Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
   *  Copyright (C) 2004 IBM Inc.
   *
   *	This program is free software; you can redistribute it and/or
   *	modify it under the terms of the GNU General Public License version
   *	2 as published by the Free Software Foundation.
   *
   *  debugfs is for people to use instead of /proc or /sys.
   *  See Documentation/DocBook/kernel-api for more details.
   *
   */

  #include <linux/module.h>
  #include <linux/fs.h>
  #include <linux/pagemap.h>

  #include <linux/namei.h>

  #include <linux/debugfs.h>
  
  static ssize_t default_read_file(struct file *file, char __user *buf,
  				 size_t count, loff_t *ppos)
  {
  	return 0;
  }
  
  static ssize_t default_write_file(struct file *file, const char __user *buf,
  				   size_t count, loff_t *ppos)
  {
  	return count;
  }
  
  static int default_open(struct inode *inode, struct file *file)
  {

  	if (inode->i_private)
  		file->private_data = inode->i_private;

  
  	return 0;
  }

  const struct file_operations debugfs_file_operations = {

  	.read =		default_read_file,
  	.write =	default_write_file,
  	.open =		default_open,
  };

  static void *debugfs_follow_link(struct dentry *dentry, struct nameidata *nd)
  {
  	nd_set_link(nd, dentry->d_inode->i_private);
  	return NULL;
  }
  
  const struct inode_operations debugfs_link_operations = {
  	.readlink       = generic_readlink,
  	.follow_link    = debugfs_follow_link,
  };

  static void debugfs_u8_set(void *data, u64 val)
  {
  	*(u8 *)data = val;
  }
  static u64 debugfs_u8_get(void *data)
  {
  	return *(u8 *)data;
  }
  DEFINE_SIMPLE_ATTRIBUTE(fops_u8, debugfs_u8_get, debugfs_u8_set, "%llu
  ");

  
  /**

   * debugfs_create_u8 - create a debugfs file that is used to read and write an unsigned 8-bit value

   * @name: a pointer to a string containing the name of the file to create.
   * @mode: the permission that the file should have
   * @parent: a pointer to the parent dentry for this file.  This should be a

   *          directory dentry if set.  If this parameter is %NULL, then the

   *          file will be created in the root of the debugfs filesystem.
   * @value: a pointer to the variable that the file should read to and write
   *         from.
   *
   * This function creates a file in debugfs with the given name that
   * contains the value of the variable @value.  If the @mode variable is so
   * set, it can be read from, and written to.
   *
   * This function will return a pointer to a dentry if it succeeds.  This
   * pointer must be passed to the debugfs_remove() function when the file is
   * to be removed (no automatic cleanup happens if your module is unloaded,

   * you are responsible here.)  If an error occurs, %NULL will be returned.

   *

   * If debugfs is not enabled in the kernel, the value -%ENODEV will be

   * returned.  It is not wise to check for this value, but rather, check for

   * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling

   * code.
   */
  struct dentry *debugfs_create_u8(const char *name, mode_t mode,
  				 struct dentry *parent, u8 *value)
  {
  	return debugfs_create_file(name, mode, parent, value, &fops_u8);
  }
  EXPORT_SYMBOL_GPL(debugfs_create_u8);

  static void debugfs_u16_set(void *data, u64 val)
  {
  	*(u16 *)data = val;
  }
  static u64 debugfs_u16_get(void *data)
  {
  	return *(u16 *)data;
  }
  DEFINE_SIMPLE_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu
  ");

  /**

   * debugfs_create_u16 - create a debugfs file that is used to read and write an unsigned 16-bit value

   * @name: a pointer to a string containing the name of the file to create.
   * @mode: the permission that the file should have
   * @parent: a pointer to the parent dentry for this file.  This should be a

   *          directory dentry if set.  If this parameter is %NULL, then the

   *          file will be created in the root of the debugfs filesystem.
   * @value: a pointer to the variable that the file should read to and write
   *         from.
   *
   * This function creates a file in debugfs with the given name that
   * contains the value of the variable @value.  If the @mode variable is so
   * set, it can be read from, and written to.
   *
   * This function will return a pointer to a dentry if it succeeds.  This
   * pointer must be passed to the debugfs_remove() function when the file is
   * to be removed (no automatic cleanup happens if your module is unloaded,

   * you are responsible here.)  If an error occurs, %NULL will be returned.

   *

   * If debugfs is not enabled in the kernel, the value -%ENODEV will be

   * returned.  It is not wise to check for this value, but rather, check for

   * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling

   * code.
   */
  struct dentry *debugfs_create_u16(const char *name, mode_t mode,
  				  struct dentry *parent, u16 *value)
  {
  	return debugfs_create_file(name, mode, parent, value, &fops_u16);
  }
  EXPORT_SYMBOL_GPL(debugfs_create_u16);

  static void debugfs_u32_set(void *data, u64 val)
  {
  	*(u32 *)data = val;
  }
  static u64 debugfs_u32_get(void *data)
  {
  	return *(u32 *)data;
  }
  DEFINE_SIMPLE_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu
  ");

  /**

   * debugfs_create_u32 - create a debugfs file that is used to read and write an unsigned 32-bit value

   * @name: a pointer to a string containing the name of the file to create.
   * @mode: the permission that the file should have
   * @parent: a pointer to the parent dentry for this file.  This should be a

   *          directory dentry if set.  If this parameter is %NULL, then the

   *          file will be created in the root of the debugfs filesystem.
   * @value: a pointer to the variable that the file should read to and write
   *         from.
   *
   * This function creates a file in debugfs with the given name that
   * contains the value of the variable @value.  If the @mode variable is so
   * set, it can be read from, and written to.
   *
   * This function will return a pointer to a dentry if it succeeds.  This
   * pointer must be passed to the debugfs_remove() function when the file is
   * to be removed (no automatic cleanup happens if your module is unloaded,

   * you are responsible here.)  If an error occurs, %NULL will be returned.

   *

   * If debugfs is not enabled in the kernel, the value -%ENODEV will be

   * returned.  It is not wise to check for this value, but rather, check for

   * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling

   * code.
   */
  struct dentry *debugfs_create_u32(const char *name, mode_t mode,
  				 struct dentry *parent, u32 *value)
  {
  	return debugfs_create_file(name, mode, parent, value, &fops_u32);
  }
  EXPORT_SYMBOL_GPL(debugfs_create_u32);

  static void debugfs_u64_set(void *data, u64 val)
  {
  	*(u64 *)data = val;
  }
  
  static u64 debugfs_u64_get(void *data)
  {
  	return *(u64 *)data;
  }
  DEFINE_SIMPLE_ATTRIBUTE(fops_u64, debugfs_u64_get, debugfs_u64_set, "%llu
  ");
  
  /**
   * debugfs_create_u64 - create a debugfs file that is used to read and write an unsigned 64-bit value
   * @name: a pointer to a string containing the name of the file to create.
   * @mode: the permission that the file should have
   * @parent: a pointer to the parent dentry for this file.  This should be a
   *          directory dentry if set.  If this parameter is %NULL, then the
   *          file will be created in the root of the debugfs filesystem.
   * @value: a pointer to the variable that the file should read to and write
   *         from.
   *
   * This function creates a file in debugfs with the given name that
   * contains the value of the variable @value.  If the @mode variable is so
   * set, it can be read from, and written to.
   *
   * This function will return a pointer to a dentry if it succeeds.  This
   * pointer must be passed to the debugfs_remove() function when the file is
   * to be removed (no automatic cleanup happens if your module is unloaded,
   * you are responsible here.)  If an error occurs, %NULL will be returned.
   *
   * If debugfs is not enabled in the kernel, the value -%ENODEV will be
   * returned.  It is not wise to check for this value, but rather, check for
   * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
   * code.
   */
  struct dentry *debugfs_create_u64(const char *name, mode_t mode,
  				 struct dentry *parent, u64 *value)
  {
  	return debugfs_create_file(name, mode, parent, value, &fops_u64);
  }
  EXPORT_SYMBOL_GPL(debugfs_create_u64);

  static ssize_t read_file_bool(struct file *file, char __user *user_buf,
  			      size_t count, loff_t *ppos)
  {
  	char buf[3];
  	u32 *val = file->private_data;
  	
  	if (*val)
  		buf[0] = 'Y';
  	else
  		buf[0] = 'N';
  	buf[1] = '
  ';
  	buf[2] = 0x00;
  	return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
  }
  
  static ssize_t write_file_bool(struct file *file, const char __user *user_buf,
  			       size_t count, loff_t *ppos)
  {
  	char buf[32];
  	int buf_size;
  	u32 *val = file->private_data;
  
  	buf_size = min(count, (sizeof(buf)-1));
  	if (copy_from_user(buf, user_buf, buf_size))
  		return -EFAULT;
  
  	switch (buf[0]) {
  	case 'y':
  	case 'Y':
  	case '1':
  		*val = 1;
  		break;
  	case 'n':
  	case 'N':
  	case '0':
  		*val = 0;
  		break;
  	}
  	
  	return count;
  }

  static const struct file_operations fops_bool = {

  	.read =		read_file_bool,
  	.write =	write_file_bool,
  	.open =		default_open,
  };
  
  /**

   * debugfs_create_bool - create a debugfs file that is used to read and write a boolean value

   * @name: a pointer to a string containing the name of the file to create.
   * @mode: the permission that the file should have
   * @parent: a pointer to the parent dentry for this file.  This should be a

   *          directory dentry if set.  If this parameter is %NULL, then the

   *          file will be created in the root of the debugfs filesystem.
   * @value: a pointer to the variable that the file should read to and write
   *         from.
   *
   * This function creates a file in debugfs with the given name that
   * contains the value of the variable @value.  If the @mode variable is so
   * set, it can be read from, and written to.
   *
   * This function will return a pointer to a dentry if it succeeds.  This
   * pointer must be passed to the debugfs_remove() function when the file is
   * to be removed (no automatic cleanup happens if your module is unloaded,

   * you are responsible here.)  If an error occurs, %NULL will be returned.

   *

   * If debugfs is not enabled in the kernel, the value -%ENODEV will be

   * returned.  It is not wise to check for this value, but rather, check for

   * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling

   * code.
   */
  struct dentry *debugfs_create_bool(const char *name, mode_t mode,
  				   struct dentry *parent, u32 *value)
  {
  	return debugfs_create_file(name, mode, parent, value, &fops_bool);
  }
  EXPORT_SYMBOL_GPL(debugfs_create_bool);

  static ssize_t read_file_blob(struct file *file, char __user *user_buf,
  			      size_t count, loff_t *ppos)
  {
  	struct debugfs_blob_wrapper *blob = file->private_data;
  	return simple_read_from_buffer(user_buf, count, ppos, blob->data,
  			blob->size);
  }

  static const struct file_operations fops_blob = {

  	.read =		read_file_blob,
  	.open =		default_open,
  };
  
  /**

   * debugfs_create_blob - create a debugfs file that is used to read and write a binary blob

   * @name: a pointer to a string containing the name of the file to create.
   * @mode: the permission that the file should have
   * @parent: a pointer to the parent dentry for this file.  This should be a

   *          directory dentry if set.  If this parameter is %NULL, then the

   *          file will be created in the root of the debugfs filesystem.
   * @blob: a pointer to a struct debugfs_blob_wrapper which contains a pointer
   *        to the blob data and the size of the data.
   *
   * This function creates a file in debugfs with the given name that exports
   * @blob->data as a binary blob. If the @mode variable is so set it can be
   * read from. Writing is not supported.
   *
   * This function will return a pointer to a dentry if it succeeds.  This
   * pointer must be passed to the debugfs_remove() function when the file is
   * to be removed (no automatic cleanup happens if your module is unloaded,

   * you are responsible here.)  If an error occurs, %NULL will be returned.

   *

   * If debugfs is not enabled in the kernel, the value -%ENODEV will be

   * returned.  It is not wise to check for this value, but rather, check for

   * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling

   * code.
   */
  struct dentry *debugfs_create_blob(const char *name, mode_t mode,
  				   struct dentry *parent,
  				   struct debugfs_blob_wrapper *blob)
  {
  	return debugfs_create_file(name, mode, parent, blob, &fops_blob);
  }
  EXPORT_SYMBOL_GPL(debugfs_create_blob);