/*
 *  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_x{8,16,32} - create a debugfs file that is used to read and write an unsigned {8,16,32}-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.
 */

/**
 * debugfs_create_x8 - 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.
 */
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);

/**
 * debugfs_create_x16 - 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.
 */
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);

/**
 * debugfs_create_x32 - 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.
 */
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);