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/*
 *  acpi_battery.c - ACPI Battery Driver ($Revision: 1.1.1.1 $)
 *
 *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or (at
 *  your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */
 
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/compatmac.h>
#include <linux/proc_fs.h>
#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>
 
 
#define _COMPONENT		ACPI_BATTERY_COMPONENT
ACPI_MODULE_NAME		("acpi_battery")
 
MODULE_AUTHOR("Paul Diefenbaugh");
MODULE_DESCRIPTION(ACPI_BATTERY_DRIVER_NAME);
MODULE_LICENSE("GPL");
 
#define PREFIX			"ACPI: "
 
 
#define ACPI_BATTERY_VALUE_UNKNOWN 0xFFFFFFFF
 
#define ACPI_BATTERY_FORMAT_BIF	"NNNNNNNNNSSSS"
#define ACPI_BATTERY_FORMAT_BST	"NNNN"
 
static int acpi_battery_add (struct acpi_device *device);
static int acpi_battery_remove (struct acpi_device *device, int type);
 
static struct acpi_driver acpi_battery_driver = {
	.name =		ACPI_BATTERY_DRIVER_NAME,
	.class =	ACPI_BATTERY_CLASS,
	.ids =		ACPI_BATTERY_HID,
	.ops =		{
				.add =		acpi_battery_add,
				.remove =	acpi_battery_remove,
			},
};
 
struct acpi_battery_status {
	acpi_integer		state;
	acpi_integer		present_rate;
	acpi_integer		remaining_capacity;
	acpi_integer		present_voltage;
};
 
struct acpi_battery_info {
	acpi_integer		power_unit;
	acpi_integer		design_capacity;
	acpi_integer		last_full_capacity;
	acpi_integer		battery_technology;
	acpi_integer		design_voltage;
	acpi_integer		design_capacity_warning;
	acpi_integer		design_capacity_low;
	acpi_integer		battery_capacity_granularity_1;
	acpi_integer		battery_capacity_granularity_2;
	acpi_string		model_number;
	acpi_string		serial_number;
	acpi_string		battery_type;
	acpi_string		oem_info;
};
 
struct acpi_battery_flags {
	u8			present:1;	/* Bay occupied? */
	u8			power_unit:1;	/* 0=watts, 1=apms */
	u8			alarm:1;	/* _BTP present? */
	u8			reserved:5;
};
 
struct acpi_battery_trips {
	unsigned long		warning;
	unsigned long		low;
};
 
struct acpi_battery {
	acpi_handle		handle;
	struct acpi_battery_flags flags;
	struct acpi_battery_trips trips;
	unsigned long		alarm;
	struct acpi_battery_info *info;
};
 
 
/* --------------------------------------------------------------------------
                               Battery Management
   -------------------------------------------------------------------------- */
 
static int
acpi_battery_get_info (
	struct acpi_battery	*battery,
	struct acpi_battery_info **bif)
{
	int			result = 0;
	acpi_status 		status = 0;
	struct acpi_buffer	buffer = {ACPI_ALLOCATE_BUFFER, NULL};
	struct acpi_buffer	format = {sizeof(ACPI_BATTERY_FORMAT_BIF),
						ACPI_BATTERY_FORMAT_BIF};
	struct acpi_buffer	data = {0, NULL};
	union acpi_object	*package = NULL;
 
	ACPI_FUNCTION_TRACE("acpi_battery_get_info");
 
	if (!battery || !bif)
		return_VALUE(-EINVAL);
 
	/* Evalute _BIF */
 
	status = acpi_evaluate_object(battery->handle, "_BIF", NULL, &buffer);
	if (ACPI_FAILURE(status)) {
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Error evaluating _BIF\n"));
		return_VALUE(-ENODEV);
	}
 
	package = (union acpi_object *) buffer.pointer;
 
	/* Extract Package Data */
 
	status = acpi_extract_package(package, &format, &data);
	if (status != AE_BUFFER_OVERFLOW) {
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Error extracting _BIF\n"));
		result = -ENODEV;
		goto end;
	}
 
	data.pointer = kmalloc(data.length, GFP_KERNEL);
	if (!data.pointer) {
		result = -ENOMEM;
		goto end;
	}
	memset(data.pointer, 0, data.length);
 
	status = acpi_extract_package(package, &format, &data);
	if (ACPI_FAILURE(status)) {
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Error extracting _BIF\n"));
		kfree(data.pointer);
		result = -ENODEV;
		goto end;
	}
 
end:
	acpi_os_free(buffer.pointer);
 
	if (!result)
		(*bif) = (struct acpi_battery_info *) data.pointer;
 
	return_VALUE(result);
}
 
static int
acpi_battery_get_status (
	struct acpi_battery	*battery,
	struct acpi_battery_status **bst)
{
	int			result = 0;
	acpi_status 		status = 0;
	struct acpi_buffer	buffer = {ACPI_ALLOCATE_BUFFER, NULL};
	struct acpi_buffer	format = {sizeof(ACPI_BATTERY_FORMAT_BST),
						ACPI_BATTERY_FORMAT_BST};
	struct acpi_buffer	data = {0, NULL};
	union acpi_object	*package = NULL;
 
	ACPI_FUNCTION_TRACE("acpi_battery_get_status");
 
	if (!battery || !bst)
		return_VALUE(-EINVAL);
 
	/* Evalute _BST */
 
	status = acpi_evaluate_object(battery->handle, "_BST", NULL, &buffer);
	if (ACPI_FAILURE(status)) {
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Error evaluating _BST\n"));
		return_VALUE(-ENODEV);
	}
 
	package = (union acpi_object *) buffer.pointer;
 
	/* Extract Package Data */
 
	status = acpi_extract_package(package, &format, &data);
	if (status != AE_BUFFER_OVERFLOW) {
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Error extracting _BST\n"));
		result = -ENODEV;
		goto end;
	}
 
	data.pointer = kmalloc(data.length, GFP_KERNEL);
	if (!data.pointer) {
		result = -ENOMEM;
		goto end;
	}
	memset(data.pointer, 0, data.length);
 
	status = acpi_extract_package(package, &format, &data);
	if (ACPI_FAILURE(status)) {
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Error extracting _BST\n"));
		kfree(data.pointer);
		result = -ENODEV;
		goto end;
	}
 
end:
	acpi_os_free(buffer.pointer);
 
	if (!result)
		(*bst) = (struct acpi_battery_status *) data.pointer;
 
	return_VALUE(result);
}
 
 
static int
acpi_battery_set_alarm (
	struct acpi_battery	*battery,
	unsigned long		alarm)
{
	acpi_status		status = 0;
	union acpi_object	arg0 = {ACPI_TYPE_INTEGER};
	struct acpi_object_list	arg_list = {1, &arg0};
 
	ACPI_FUNCTION_TRACE("acpi_battery_set_alarm");
 
	if (!battery)
		return_VALUE(-EINVAL);
 
	if (!battery->flags.alarm)
		return_VALUE(-ENODEV);
 
	arg0.integer.value = alarm;
 
	status = acpi_evaluate_object(battery->handle, "_BTP", &arg_list, NULL);
	if (ACPI_FAILURE(status))
		return_VALUE(-ENODEV);
 
	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Alarm set to %d\n", (u32) alarm));
 
	battery->alarm = alarm;
 
	return_VALUE(0);
}
 
 
static int
acpi_battery_check (
	struct acpi_battery	*battery)
{
	int			result = 0;
	acpi_status		status = AE_OK;
	acpi_handle		handle = NULL;
	struct acpi_device	*device = NULL;
	struct acpi_battery_info *bif = NULL;
 
	ACPI_FUNCTION_TRACE("acpi_battery_check");
 
	if (!battery)
		return_VALUE(-EINVAL);
 
	result = acpi_bus_get_device(battery->handle, &device);
	if (result)
		return_VALUE(result);
 
	result = acpi_bus_get_status(device);
	if (result)
		return_VALUE(result);
 
	/* Insertion? */
 
	if (!battery->flags.present && device->status.battery_present) {
 
		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Battery inserted\n"));
 
		/* Evalute _BIF to get certain static information */
 
		result = acpi_battery_get_info(battery, &bif);
		if (result)
			return_VALUE(result);
 
		battery->flags.power_unit = bif->power_unit;
		battery->trips.warning = bif->design_capacity_warning;
		battery->trips.low = bif->design_capacity_low;
		kfree(bif);
 
		/* See if alarms are supported, and if so, set default */
 
		status = acpi_get_handle(battery->handle, "_BTP", &handle);
		if (ACPI_SUCCESS(status)) {
			battery->flags.alarm = 1;
			acpi_battery_set_alarm(battery, battery->trips.warning);
		}
	}
 
	/* Removal? */
 
	else if (battery->flags.present && !device->status.battery_present) {
		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Battery removed\n"));
	}
 
	battery->flags.present = device->status.battery_present;
 
	return_VALUE(result);
}
 
 
/* --------------------------------------------------------------------------
                              FS Interface (/proc)
   -------------------------------------------------------------------------- */
 
struct proc_dir_entry		*acpi_battery_dir;
 
static int
acpi_battery_read_info (
	char			*page,
	char			**start,
	off_t			off,
	int 			count,
	int 			*eof,
	void			*data)
{
	int			result = 0;
	struct acpi_battery	*battery = (struct acpi_battery *) data;
	struct acpi_battery_info *bif = NULL;
	char			*units = "?";
	char			*p = page;
	int			len = 0;
 
	ACPI_FUNCTION_TRACE("acpi_battery_read_info");
 
	if (!battery || (off != 0))
		goto end;
 
	if (battery->flags.present)
		p += sprintf(p, "present:                 yes\n");
	else {
		p += sprintf(p, "present:                 no\n");
		goto end;
	}
 
	/* Battery Info (_BIF) */
 
	result = acpi_battery_get_info(battery, &bif);
	if (result || !bif) {
		p += sprintf(p, "ERROR: Unable to read battery information\n");
		goto end;
	}
 
	units = bif->power_unit ? ACPI_BATTERY_UNITS_AMPS : ACPI_BATTERY_UNITS_WATTS;
 
	if (bif->design_capacity == ACPI_BATTERY_VALUE_UNKNOWN)
		p += sprintf(p, "design capacity:         unknown\n");
	else
		p += sprintf(p, "design capacity:         %d %sh\n",
			(u32) bif->design_capacity, units);
 
	if (bif->last_full_capacity == ACPI_BATTERY_VALUE_UNKNOWN)
		p += sprintf(p, "last full capacity:      unknown\n");
	else
		p += sprintf(p, "last full capacity:      %d %sh\n",
			(u32) bif->last_full_capacity, units);
 
	switch ((u32) bif->battery_technology) {
	case 0:
		p += sprintf(p, "battery technology:      non-rechargeable\n");
		break;
	case 1:
		p += sprintf(p, "battery technology:      rechargeable\n");
		break;
	default:
		p += sprintf(p, "battery technology:      unknown\n");
		break;
	}
 
	if (bif->design_voltage == ACPI_BATTERY_VALUE_UNKNOWN)
		p += sprintf(p, "design voltage:          unknown\n");
	else
		p += sprintf(p, "design voltage:          %d mV\n",
			(u32) bif->design_voltage);
 
	p += sprintf(p, "design capacity warning: %d %sh\n",
		(u32) bif->design_capacity_warning, units);
	p += sprintf(p, "design capacity low:     %d %sh\n",
		(u32) bif->design_capacity_low, units);
	p += sprintf(p, "capacity granularity 1:  %d %sh\n",
		(u32) bif->battery_capacity_granularity_1, units);
	p += sprintf(p, "capacity granularity 2:  %d %sh\n",
		(u32) bif->battery_capacity_granularity_2, units);
	p += sprintf(p, "model number:            %s\n",
		bif->model_number);
	p += sprintf(p, "serial number:           %s\n",
		bif->serial_number);
	p += sprintf(p, "battery type:            %s\n",
		bif->battery_type);
	p += sprintf(p, "OEM info:                %s\n",
		bif->oem_info);
 
end:
	kfree(bif);
 
	len = (p - page);
	if (len <= off+count) *eof = 1;
	*start = page + off;
	len -= off;
	if (len>count) len = count;
	if (len<0) len = 0;
 
	return_VALUE(len);
}
 
 
static int
acpi_battery_read_state (
	char			*page,
	char			**start,
	off_t			off,
	int 			count,
	int 			*eof,
	void			*data)
{
	int			result = 0;
	struct acpi_battery	*battery = (struct acpi_battery *) data;
	struct acpi_battery_status *bst = NULL;
	char			*units = "?";
	char			*p = page;
	int			len = 0;
 
	ACPI_FUNCTION_TRACE("acpi_battery_read_state");
 
	if (!battery || (off != 0))
		goto end;
 
	if (battery->flags.present)
		p += sprintf(p, "present:                 yes\n");
	else {
		p += sprintf(p, "present:                 no\n");
		goto end;
	}
 
	/* Battery Units */
 
	units = battery->flags.power_unit ? ACPI_BATTERY_UNITS_AMPS : ACPI_BATTERY_UNITS_WATTS;
 
	/* Battery Status (_BST) */
 
	result = acpi_battery_get_status(battery, &bst);
	if (result || !bst) {
		p += sprintf(p, "ERROR: Unable to read battery status\n");
		goto end;
	}
 
	if (!(bst->state & 0x04))
		p += sprintf(p, "capacity state:          ok\n");
	else
		p += sprintf(p, "capacity state:          critical\n");
 
	if ((bst->state & 0x01) && (bst->state & 0x02))
		p += sprintf(p, "charging state:          charging/discharging\n");
	else if (bst->state & 0x01)
		p += sprintf(p, "charging state:          discharging\n");
	else if (bst->state & 0x02)
		p += sprintf(p, "charging state:          charging\n");
	else
		p += sprintf(p, "charging state:          unknown\n");
 
	if (bst->present_rate == ACPI_BATTERY_VALUE_UNKNOWN)
		p += sprintf(p, "present rate:            unknown\n");
	else
		p += sprintf(p, "present rate:            %d %s\n",
			(u32) bst->present_rate, units);
 
	if (bst->remaining_capacity == ACPI_BATTERY_VALUE_UNKNOWN)
		p += sprintf(p, "remaining capacity:      unknown\n");
	else
		p += sprintf(p, "remaining capacity:      %d %sh\n",
			(u32) bst->remaining_capacity, units);
 
	if (bst->present_voltage == ACPI_BATTERY_VALUE_UNKNOWN)
		p += sprintf(p, "present voltage:         unknown\n");
	else
		p += sprintf(p, "present voltage:         %d mV\n",
			(u32) bst->present_voltage);
 
end:
	kfree(bst);
 
	len = (p - page);
	if (len <= off+count) *eof = 1;
	*start = page + off;
	len -= off;
	if (len>count) len = count;
	if (len<0) len = 0;
 
	return_VALUE(len);
}
 
 
static int
acpi_battery_read_alarm (
	char			*page,
	char			**start,
	off_t			off,
	int 			count,
	int 			*eof,
	void			*data)
{
	struct acpi_battery	*battery = (struct acpi_battery *) data;
	char			*units = "?";
	char			*p = page;
	int			len = 0;
 
	ACPI_FUNCTION_TRACE("acpi_battery_read_alarm");
 
	if (!battery || (off != 0))
		goto end;
 
	if (!battery->flags.present) {
		p += sprintf(p, "present:                 no\n");
		goto end;
	}
 
	/* Battery Units */
 
	units = battery->flags.power_unit ? ACPI_BATTERY_UNITS_AMPS : ACPI_BATTERY_UNITS_WATTS;
 
	/* Battery Alarm */
 
	p += sprintf(p, "alarm:                   ");
	if (!battery->alarm)
		p += sprintf(p, "unsupported\n");
	else
		p += sprintf(p, "%d %sh\n", (u32) battery->alarm, units);
 
end:
	len = (p - page);
	if (len <= off+count) *eof = 1;
	*start = page + off;
	len -= off;
	if (len>count) len = count;
	if (len<0) len = 0;
 
	return_VALUE(len);
}
 
 
static int
acpi_battery_write_alarm (
	struct file		*file,
	const char		*buffer,
	unsigned long		count,
	void			*data)
{
	int			result = 0;
	struct acpi_battery	*battery = (struct acpi_battery *) data;
	char			alarm_string[12] = {'\0'};
 
	ACPI_FUNCTION_TRACE("acpi_battery_write_alarm");
 
	if (!battery || (count > sizeof(alarm_string) - 1))
		return_VALUE(-EINVAL);
 
	if (!battery->flags.present)
		return_VALUE(-ENODEV);
 
	if (copy_from_user(alarm_string, buffer, count))
		return_VALUE(-EFAULT);
 
	alarm_string[count] = '\0';
 
	result = acpi_battery_set_alarm(battery, 
		simple_strtoul(alarm_string, NULL, 0));
	if (result)
		return_VALUE(result);
 
	return_VALUE(count);
}
 
 
static int
acpi_battery_add_fs (
	struct acpi_device	*device)
{
	struct proc_dir_entry	*entry = NULL;
 
	ACPI_FUNCTION_TRACE("acpi_battery_add_fs");
 
	if (!acpi_device_dir(device)) {
		acpi_device_dir(device) = proc_mkdir(acpi_device_bid(device),
			acpi_battery_dir);
		if (!acpi_device_dir(device))
			return_VALUE(-ENODEV);
	}
 
	/* 'info' [R] */
	entry = create_proc_entry(ACPI_BATTERY_FILE_INFO,
		S_IRUGO, acpi_device_dir(device));
	if (!entry)
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
			"Unable to create '%s' fs entry\n",
			ACPI_BATTERY_FILE_INFO));
	else {
		entry->read_proc = acpi_battery_read_info;
		entry->data = acpi_driver_data(device);
	}
 
	/* 'status' [R] */
	entry = create_proc_entry(ACPI_BATTERY_FILE_STATUS,
		S_IRUGO, acpi_device_dir(device));
	if (!entry)
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
			"Unable to create '%s' fs entry\n",
			ACPI_BATTERY_FILE_STATUS));
	else {
		entry->read_proc = acpi_battery_read_state;
		entry->data = acpi_driver_data(device);
	}
 
	/* 'alarm' [R/W] */
	entry = create_proc_entry(ACPI_BATTERY_FILE_ALARM,
		S_IFREG|S_IRUGO|S_IWUSR, acpi_device_dir(device));
	if (!entry)
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
			"Unable to create '%s' fs entry\n",
			ACPI_BATTERY_FILE_ALARM));
	else {
		entry->read_proc = acpi_battery_read_alarm;
		entry->write_proc = acpi_battery_write_alarm;
		entry->data = acpi_driver_data(device);
	}
 
	return_VALUE(0);
}
 
 
static int
acpi_battery_remove_fs (
	struct acpi_device	*device)
{
	ACPI_FUNCTION_TRACE("acpi_battery_remove_fs");
 
	if (acpi_device_dir(device)) {
		remove_proc_entry(acpi_device_bid(device), acpi_battery_dir);
		acpi_device_dir(device) = NULL;
	}
 
	return_VALUE(0);
}
 
 
/* --------------------------------------------------------------------------
                                 Driver Interface
   -------------------------------------------------------------------------- */
 
static void
acpi_battery_notify (
	acpi_handle		handle,
	u32			event,
	void			*data)
{
	struct acpi_battery	*battery = (struct acpi_battery *) data;
	struct acpi_device	*device = NULL;
 
	ACPI_FUNCTION_TRACE("acpi_battery_notify");
 
	if (!battery)
		return_VOID;
 
	if (acpi_bus_get_device(handle, &device))
		return_VOID;
 
	switch (event) {
	case ACPI_BATTERY_NOTIFY_STATUS:
	case ACPI_BATTERY_NOTIFY_INFO:
		acpi_battery_check(battery);
		acpi_bus_generate_event(device, event, battery->flags.present);
		break;
	default:
		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
			"Unsupported event [0x%x]\n", event));
		break;
	}
 
	return_VOID;
}
 
 
static int
acpi_battery_add (
	struct acpi_device	*device)
{
	int			result = 0;
	acpi_status		status = 0;
	struct acpi_battery	*battery = NULL;
 
	ACPI_FUNCTION_TRACE("acpi_battery_add");
 
	if (!device)
		return_VALUE(-EINVAL);
 
	battery = kmalloc(sizeof(struct acpi_battery), GFP_KERNEL);
	if (!battery)
		return_VALUE(-ENOMEM);
	memset(battery, 0, sizeof(struct acpi_battery));
 
	battery->handle = device->handle;
	sprintf(acpi_device_name(device), "%s", ACPI_BATTERY_DEVICE_NAME);
	sprintf(acpi_device_class(device), "%s", ACPI_BATTERY_CLASS);
	acpi_driver_data(device) = battery;
 
	result = acpi_battery_check(battery);
	if (result)
		goto end;
 
	result = acpi_battery_add_fs(device);
	if (result)
		goto end;
 
	status = acpi_install_notify_handler(battery->handle,
		ACPI_DEVICE_NOTIFY, acpi_battery_notify, battery);
	if (ACPI_FAILURE(status)) {
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
			"Error installing notify handler\n"));
		result = -ENODEV;
		goto end;
	}
 
	printk(KERN_INFO PREFIX "%s Slot [%s] (battery %s)\n",
		ACPI_BATTERY_DEVICE_NAME, acpi_device_bid(device),
		device->status.battery_present?"present":"absent");
 
end:
	if (result) {
		acpi_battery_remove_fs(device);
		kfree(battery);
	}
 
	return_VALUE(result);
}
 
 
static int
acpi_battery_remove (
	struct acpi_device	*device,
	int			type)
{
	acpi_status		status = 0;
	struct acpi_battery	*battery = NULL;
 
	ACPI_FUNCTION_TRACE("acpi_battery_remove");
 
	if (!device || !acpi_driver_data(device))
		return_VALUE(-EINVAL);
 
	battery = (struct acpi_battery *) acpi_driver_data(device);
 
	status = acpi_remove_notify_handler(battery->handle,
		ACPI_DEVICE_NOTIFY, acpi_battery_notify);
	if (ACPI_FAILURE(status))
		ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
			"Error removing notify handler\n"));
 
	acpi_battery_remove_fs(device);
 
	kfree(battery);
 
	return_VALUE(0);
}
 
 
static int __init
acpi_battery_init (void)
{
	int			result = 0;
 
	ACPI_FUNCTION_TRACE("acpi_battery_init");
 
	acpi_battery_dir = proc_mkdir(ACPI_BATTERY_CLASS, acpi_root_dir);
	if (!acpi_battery_dir)
		return_VALUE(-ENODEV);
 
	result = acpi_bus_register_driver(&acpi_battery_driver);
	if (result < 0) {
		remove_proc_entry(ACPI_BATTERY_CLASS, acpi_root_dir);
		return_VALUE(-ENODEV);
	}
 
	return_VALUE(0);
}
 
 
static void __exit
acpi_battery_exit (void)
{
	ACPI_FUNCTION_TRACE("acpi_battery_exit");
 
	acpi_bus_unregister_driver(&acpi_battery_driver);
 
	remove_proc_entry(ACPI_BATTERY_CLASS, acpi_root_dir);
 
	return_VOID;
}
 
 
module_init(acpi_battery_init);
module_exit(acpi_battery_exit);