/*
   * ec_sys.c
   *
   * Copyright (C) 2010 SUSE Products GmbH/Novell
   * Author:
   *      Thomas Renninger <trenn@suse.de>
   *
   * This work is licensed under the terms of the GNU GPL, version 2.
   */

  #include <linux/kernel.h>
  #include <linux/acpi.h>
  #include <linux/debugfs.h>

  #include <linux/module.h>

  #include <linux/uaccess.h>

  #include "internal.h"
  
  MODULE_AUTHOR("Thomas Renninger <trenn@suse.de>");
  MODULE_DESCRIPTION("ACPI EC sysfs access driver");
  MODULE_LICENSE("GPL");

  static bool write_support;
  module_param(write_support, bool, 0644);
  MODULE_PARM_DESC(write_support, "Dangerous, reboot and removal of battery may "
  		 "be needed.");

  #define EC_SPACE_SIZE 256

  static struct dentry *acpi_ec_debugfs_dir;

  static ssize_t acpi_ec_read_io(struct file *f, char __user *buf,
  			       size_t count, loff_t *off)
  {
  	/* Use this if support reading/writing multiple ECs exists in ec.c:
  	 * struct acpi_ec *ec = ((struct seq_file *)f->private_data)->private;
  	 */
  	unsigned int size = EC_SPACE_SIZE;

  	loff_t init_off = *off;
  	int err = 0;
  
  	if (*off >= size)
  		return 0;
  	if (*off + count >= size) {
  		size -= *off;
  		count = size;
  	} else
  		size = count;
  
  	while (size) {

  		u8 byte_read;
  		err = ec_read(*off, &byte_read);

  		if (err)
  			return err;

  		if (put_user(byte_read, buf + *off - init_off)) {
  			if (*off - init_off)
  				return *off - init_off; /* partial read */
  			return -EFAULT;
  		}

  		*off += 1;
  		size--;
  	}
  	return count;
  }
  
  static ssize_t acpi_ec_write_io(struct file *f, const char __user *buf,
  				size_t count, loff_t *off)
  {
  	/* Use this if support reading/writing multiple ECs exists in ec.c:
  	 * struct acpi_ec *ec = ((struct seq_file *)f->private_data)->private;
  	 */
  
  	unsigned int size = count;
  	loff_t init_off = *off;

  	int err = 0;

  	if (!write_support)
  		return -EINVAL;

  	if (*off >= EC_SPACE_SIZE)
  		return 0;
  	if (*off + count >= EC_SPACE_SIZE) {
  		size = EC_SPACE_SIZE - *off;
  		count = size;
  	}
  
  	while (size) {

  		u8 byte_write;
  		if (get_user(byte_write, buf + *off - init_off)) {
  			if (*off - init_off)
  				return *off - init_off; /* partial write */
  			return -EFAULT;
  		}

  		err = ec_write(*off, byte_write);
  		if (err)
  			return err;
  
  		*off += 1;
  		size--;
  	}
  	return count;
  }

  static const struct file_operations acpi_ec_io_ops = {

  	.owner = THIS_MODULE,

  	.open  = simple_open,

  	.read  = acpi_ec_read_io,
  	.write = acpi_ec_write_io,

  	.llseek = default_llseek,

  };

  static int acpi_ec_add_debugfs(struct acpi_ec *ec, unsigned int ec_device_count)

  {
  	struct dentry *dev_dir;
  	char name[64];

  	umode_t mode = 0400;

  	if (ec_device_count == 0) {
  		acpi_ec_debugfs_dir = debugfs_create_dir("ec", NULL);
  		if (!acpi_ec_debugfs_dir)
  			return -ENOMEM;
  	}
  
  	sprintf(name, "ec%u", ec_device_count);
  	dev_dir = debugfs_create_dir(name, acpi_ec_debugfs_dir);
  	if (!dev_dir) {

  		if (ec_device_count != 0)
  			goto error;

  		return -ENOMEM;
  	}

  	if (!debugfs_create_x32("gpe", 0444, dev_dir, (u32 *)&first_ec->gpe))
  		goto error;
  	if (!debugfs_create_bool("use_global_lock", 0444, dev_dir,

  				 &first_ec->global_lock))

  		goto error;
  
  	if (write_support)
  		mode = 0600;
  	if (!debugfs_create_file("io", mode, dev_dir, ec, &acpi_ec_io_ops))
  		goto error;

  	return 0;

  
  error:
  	debugfs_remove_recursive(acpi_ec_debugfs_dir);
  	return -ENOMEM;

  }
  
  static int __init acpi_ec_sys_init(void)
  {
  	int err = 0;
  	if (first_ec)
  		err = acpi_ec_add_debugfs(first_ec, 0);
  	else
  		err = -ENODEV;
  	return err;
  }
  
  static void __exit acpi_ec_sys_exit(void)
  {
  	debugfs_remove_recursive(acpi_ec_debugfs_dir);
  }
  
  module_init(acpi_ec_sys_init);
  module_exit(acpi_ec_sys_exit);