fs/debugfs/file.c - kernel/msm-4.9 - Gitiles

 /*
  *  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\n");

 /**
  * 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\n");

 /**
  * 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\n");

 /**
  * 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\n");

 /**
  * 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);

 DEFINE_SIMPLE_ATTRIBUTE(fops_x8, debugfs_u8_get, debugfs_u8_set, "0x%02llx\n");

 DEFINE_SIMPLE_ATTRIBUTE(fops_x16, debugfs_u16_get, debugfs_u16_set, "0x%04llx\n");

 DEFINE_SIMPLE_ATTRIBUTE(fops_x32, debugfs_u32_get, debugfs_u32_set, "0x%08llx\n");

 /**
  * debugfs_create_x8 - create a debugfs file that is used to read and write an unsigned 8-bit value
  * debugfs_create_x16 - create a debugfs file that is used to read and write an unsigned 16-bit value
  * debugfs_create_x32 - create a debugfs file that is used to read and write an unsigned 32-bit value
  *
  * These functions are exactly the same as the above functions, (but use a hex
  * output for the decimal challenged) for details look at the above unsigned
  * decimal functions.
  */
 struct dentry *debugfs_create_x8(const char *name, mode_t mode,
 				 struct dentry *parent, u8 *value)
 {
 	return debugfs_create_file(name, mode, parent, value, &fops_x8);
 }
 EXPORT_SYMBOL_GPL(debugfs_create_x8);

 struct dentry *debugfs_create_x16(const char *name, mode_t mode,
 				 struct dentry *parent, u16 *value)
 {
 	return debugfs_create_file(name, mode, parent, value, &fops_x16);
 }
 EXPORT_SYMBOL_GPL(debugfs_create_x16);

 struct dentry *debugfs_create_x32(const char *name, mode_t mode,
 				 struct dentry *parent, u32 *value)
 {
 	return debugfs_create_file(name, mode, parent, value, &fops_x32);
 }
 EXPORT_SYMBOL_GPL(debugfs_create_x32);

 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] = '\n';
 	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);
	/*
	* 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\n");

	/**
	* 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\n");

	/**
	* 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\n");

	/**
	* 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\n");

	/**
	* 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);

	DEFINE_SIMPLE_ATTRIBUTE(fops_x8, debugfs_u8_get, debugfs_u8_set, "0x%02llx\n");

	DEFINE_SIMPLE_ATTRIBUTE(fops_x16, debugfs_u16_get, debugfs_u16_set, "0x%04llx\n");

	DEFINE_SIMPLE_ATTRIBUTE(fops_x32, debugfs_u32_get, debugfs_u32_set, "0x%08llx\n");

	/**
	* debugfs_create_x8 - create a debugfs file that is used to read and write an unsigned 8-bit value
	* debugfs_create_x16 - create a debugfs file that is used to read and write an unsigned 16-bit value
	* debugfs_create_x32 - create a debugfs file that is used to read and write an unsigned 32-bit value
	*
	* These functions are exactly the same as the above functions, (but use a hex
	* output for the decimal challenged) for details look at the above unsigned
	* decimal functions.
	*/
	struct dentry debugfs_create_x8(const char name, mode_t mode,
	struct dentry parent, u8 value)
	{
	return debugfs_create_file(name, mode, parent, value, &fops_x8);
	}
	EXPORT_SYMBOL_GPL(debugfs_create_x8);

	struct dentry debugfs_create_x16(const char name, mode_t mode,
	struct dentry parent, u16 value)
	{
	return debugfs_create_file(name, mode, parent, value, &fops_x16);
	}
	EXPORT_SYMBOL_GPL(debugfs_create_x16);

	struct dentry debugfs_create_x32(const char name, mode_t mode,
	struct dentry parent, u32 value)
	{
	return debugfs_create_file(name, mode, parent, value, &fops_x32);
	}
	EXPORT_SYMBOL_GPL(debugfs_create_x32);

	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] = '\n';
	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);