wmi.c

/*
 *  ACPI-WMI mapping driver
 *
 *  Copyright (C) 2007-2008 Carlos Corbacho <carlos@strangeworlds.co.uk>
 *
 *  GUID parsing code from ldm.c is:
 *   Copyright (C) 2001,2002 Richard Russon <ldm@flatcap.org>
 *   Copyright (c) 2001-2007 Anton Altaparmakov
 *   Copyright (C) 2001,2002 Jakob Kemi <jakob.kemi@telia.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.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/device.h>
#include <linux/list.h>
#include <linux/acpi.h>
#include <linux/slab.h>
#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>

ACPI_MODULE_NAME("wmi");
MODULE_AUTHOR("Carlos Corbacho");
MODULE_DESCRIPTION("ACPI-WMI Mapping Driver");
MODULE_LICENSE("GPL");

#define ACPI_WMI_CLASS "wmi"

static DEFINE_MUTEX(wmi_data_lock);
static LIST_HEAD(wmi_block_list);

struct guid_block {
	char guid[16];
	union {
		char object_id[2];
		struct {
			unsigned char notify_id;
			unsigned char reserved;
		};
	};
	u8 instance_count;
	u8 flags;
};

struct wmi_block {
	struct list_head list;
	struct guid_block gblock;
	acpi_handle handle;
	wmi_notify_handler handler;
	void *handler_data;
	struct device dev;
};


/*
 * If the GUID data block is marked as expensive, we must enable and
 * explicitily disable data collection.
 */
#define ACPI_WMI_EXPENSIVE   0x1
#define ACPI_WMI_METHOD      0x2	/* GUID is a method */
#define ACPI_WMI_STRING      0x4	/* GUID takes & returns a string */
#define ACPI_WMI_EVENT       0x8	/* GUID is an event */

static int debug_event;
module_param(debug_event, bool, 0444);
MODULE_PARM_DESC(debug_event,
		 "Log WMI Events [0/1]");

static int debug_dump_wdg;
module_param(debug_dump_wdg, bool, 0444);
MODULE_PARM_DESC(debug_dump_wdg,
		 "Dump available WMI interfaces [0/1]");

static int acpi_wmi_remove(struct acpi_device *device, int type);
static int acpi_wmi_add(struct acpi_device *device);
static void acpi_wmi_notify(struct acpi_device *device, u32 event);

static const struct acpi_device_id wmi_device_ids[] = {
	{"PNP0C14", 0},
	{"pnp0c14", 0},
	{"", 0},
};
MODULE_DEVICE_TABLE(acpi, wmi_device_ids);

static struct acpi_driver acpi_wmi_driver = {
	.name = "wmi",
	.class = ACPI_WMI_CLASS,
	.ids = wmi_device_ids,
	.ops = {
		.add = acpi_wmi_add,
		.remove = acpi_wmi_remove,
		.notify = acpi_wmi_notify,
	},
};

/*
 * GUID parsing functions
 */

/**
 * wmi_parse_hexbyte - Convert a ASCII hex number to a byte
 * @src:  Pointer to at least 2 characters to convert.
 *
 * Convert a two character ASCII hex string to a number.
 *
 * Return:  0-255  Success, the byte was parsed correctly
 *          -1     Error, an invalid character was supplied
 */
static int wmi_parse_hexbyte(const u8 *src)
{
	int h;
	int value;

	/* high part */
	h = value = hex_to_bin(src[0]);
	if (value < 0)
		return -1;

	/* low part */
	value = hex_to_bin(src[1]);
	if (value >= 0)
		return (h << 4) | value;
	return -1;
}

/**
 * wmi_swap_bytes - Rearrange GUID bytes to match GUID binary
 * @src:   Memory block holding binary GUID (16 bytes)
 * @dest:  Memory block to hold byte swapped binary GUID (16 bytes)
 *
 * Byte swap a binary GUID to match it's real GUID value
 */
static void wmi_swap_bytes(u8 *src, u8 *dest)
{
	int i;

	for (i = 0; i <= 3; i++)
		memcpy(dest + i, src + (3 - i), 1);

	for (i = 0; i <= 1; i++)
		memcpy(dest + 4 + i, src + (5 - i), 1);

	for (i = 0; i <= 1; i++)
		memcpy(dest + 6 + i, src + (7 - i), 1);

	memcpy(dest + 8, src + 8, 8);
}

/**
 * wmi_parse_guid - Convert GUID from ASCII to binary
 * @src:   36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
 * @dest:  Memory block to hold binary GUID (16 bytes)
 *
 * N.B. The GUID need not be NULL terminated.
 *
 * Return:  'true'   @dest contains binary GUID
 *          'false'  @dest contents are undefined
 */
static bool wmi_parse_guid(const u8 *src, u8 *dest)
{
	static const int size[] = { 4, 2, 2, 2, 6 };
	int i, j, v;

	if (src[8]  != '-' || src[13] != '-' ||
		src[18] != '-' || src[23] != '-')
		return false;

	for (j = 0; j < 5; j++, src++) {
		for (i = 0; i < size[j]; i++, src += 2, *dest++ = v) {
			v = wmi_parse_hexbyte(src);
			if (v < 0)
				return false;
		}
	}

	return true;
}

/*
 * Convert a raw GUID to the ACII string representation
 */
static int wmi_gtoa(const char *in, char *out)
{
	int i;

	for (i = 3; i >= 0; i--)
		out += sprintf(out, "%02X", in[i] & 0xFF);

	out += sprintf(out, "-");
	out += sprintf(out, "%02X", in[5] & 0xFF);
	out += sprintf(out, "%02X", in[4] & 0xFF);
	out += sprintf(out, "-");
	out += sprintf(out, "%02X", in[7] & 0xFF);
	out += sprintf(out, "%02X", in[6] & 0xFF);
	out += sprintf(out, "-");
	out += sprintf(out, "%02X", in[8] & 0xFF);
	out += sprintf(out, "%02X", in[9] & 0xFF);
	out += sprintf(out, "-");

	for (i = 10; i <= 15; i++)
		out += sprintf(out, "%02X", in[i] & 0xFF);

	*out = '\0';
	return 0;
}

static bool find_guid(const char *guid_string, struct wmi_block **out)
{
	char tmp[16], guid_input[16];
	struct wmi_block *wblock;
	struct guid_block *block;
	struct list_head *p;

	wmi_parse_guid(guid_string, tmp);
	wmi_swap_bytes(tmp, guid_input);

	list_for_each(p, &wmi_block_list) {
		wblock = list_entry(p, struct wmi_block, list);
		block = &wblock->gblock;

		if (memcmp(block->guid, guid_input, 16) == 0) {
			if (out)
				*out = wblock;
			return 1;
		}
	}
	return 0;
}

static acpi_status wmi_method_enable(struct wmi_block *wblock, int enable)
{
	struct guid_block *block = NULL;
	char method[5];
	struct acpi_object_list input;
	union acpi_object params[1];
	acpi_status status;
	acpi_handle handle;

	block = &wblock->gblock;
	handle = wblock->handle;

	if (!block)
		return AE_NOT_EXIST;

	input.count = 1;
	input.pointer = params;
	params[0].type = ACPI_TYPE_INTEGER;
	params[0].integer.value = enable;

	snprintf(method, 5, "WE%02X", block->notify_id);
	status = acpi_evaluate_object(handle, method, &input, NULL);

	if (status != AE_OK && status != AE_NOT_FOUND)
		return status;
	else
		return AE_OK;
}

/*
 * Exported WMI functions
 */
/**
 * wmi_evaluate_method - Evaluate a WMI method
 * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
 * @instance: Instance index
 * @method_id: Method ID to call
 * &in: Buffer containing input for the method call
 * &out: Empty buffer to return the method results
 *
 * Call an ACPI-WMI method
 */
acpi_status wmi_evaluate_method(const char *guid_string, u8 instance,
u32 method_id, const struct acpi_buffer *in, struct acpi_buffer *out)
{
	struct guid_block *block = NULL;
	struct wmi_block *wblock = NULL;
	acpi_handle handle;
	acpi_status status;
	struct acpi_object_list input;
	union acpi_object params[3];
	char method[5] = "WM";

	if (!find_guid(guid_string, &wblock))
		return AE_ERROR;

	block = &wblock->gblock;
	handle = wblock->handle;

	if (!(block->flags & ACPI_WMI_METHOD))
		return AE_BAD_DATA;

	if (block->instance_count < instance)
		return AE_BAD_PARAMETER;

	input.count = 2;
	input.pointer = params;
	params[0].type = ACPI_TYPE_INTEGER;
	params[0].integer.value = instance;
	params[1].type = ACPI_TYPE_INTEGER;
	params[1].integer.value = method_id;

	if (in) {
		input.count = 3;

		if (block->flags & ACPI_WMI_STRING) {
			params[2].type = ACPI_TYPE_STRING;
		} else {
			params[2].type = ACPI_TYPE_BUFFER;
		}
		params[2].buffer.length = in->length;
		params[2].buffer.pointer = in->pointer;
	}

	strncat(method, block->object_id, 2);

	status = acpi_evaluate_object(handle, method, &input, out);

	return status;
}
EXPORT_SYMBOL_GPL(wmi_evaluate_method);

/**
 * wmi_query_block - Return contents of a WMI block
 * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
 * @instance: Instance index
 * &out: Empty buffer to return the contents of the data block to
 *
 * Return the contents of an ACPI-WMI data block to a buffer
 */
acpi_status wmi_query_block(const char *guid_string, u8 instance,
struct acpi_buffer *out)
{
	struct guid_block *block = NULL;
	struct wmi_block *wblock = NULL;
	acpi_handle handle, wc_handle;
	acpi_status status, wc_status = AE_ERROR;
	struct acpi_object_list input, wc_input;
	union acpi_object wc_params[1], wq_params[1];
	char method[5];
	char wc_method[5] = "WC";

	if (!guid_string || !out)
		return AE_BAD_PARAMETER;

	if (!find_guid(guid_string, &wblock))
		return AE_ERROR;

	block = &wblock->gblock;
	handle = wblock->handle;

	if (block->instance_count < instance)
		return AE_BAD_PARAMETER;

	/* Check GUID is a data block */
	if (block->flags & (ACPI_WMI_EVENT | ACPI_WMI_METHOD))
		return AE_ERROR;

	input.count = 1;
	input.pointer = wq_params;
	wq_params[0].type = ACPI_TYPE_INTEGER;
	wq_params[0].integer.value = instance;

	/*
	 * If ACPI_WMI_EXPENSIVE, call the relevant WCxx method first to
	 * enable collection.
	 */
	if (block->flags & ACPI_WMI_EXPENSIVE) {
		wc_input.count = 1;
		wc_input.pointer = wc_params;
		wc_params[0].type = ACPI_TYPE_INTEGER;
		wc_params[0].integer.value = 1;

		strncat(wc_method, block->object_id, 2);

		/*
		 * Some GUIDs break the specification by declaring themselves
		 * expensive, but have no corresponding WCxx method. So we
		 * should not fail if this happens.
		 */
		wc_status = acpi_get_handle(handle, wc_method, &wc_handle);
		if (ACPI_SUCCESS(wc_status))
			wc_status = acpi_evaluate_object(handle, wc_method,
				&wc_input, NULL);
	}

	strcpy(method, "WQ");
	strncat(method, block->object_id, 2);

	status = acpi_evaluate_object(handle, method, &input, out);

	/*
	 * If ACPI_WMI_EXPENSIVE, call the relevant WCxx method, even if
	 * the WQxx method failed - we should disable collection anyway.
	 */
	if ((block->flags & ACPI_WMI_EXPENSIVE) && ACPI_SUCCESS(wc_status)) {
		wc_params[0].integer.value = 0;
		status = acpi_evaluate_object(handle,
		wc_method, &wc_input, NULL);
	}

	return status;
}
EXPORT_SYMBOL_GPL(wmi_query_block);

/**
 * wmi_set_block - Write to a WMI block
 * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
 * @instance: Instance index
 * &in: Buffer containing new values for the data block
 *
 * Write the contents of the input buffer to an ACPI-WMI data block
 */
acpi_status wmi_set_block(const char *guid_string, u8 instance,
const struct acpi_buffer *in)
{
	struct guid_block *block = NULL;
	struct wmi_block *wblock = NULL;
	acpi_handle handle;
	struct acpi_object_list input;
	union acpi_object params[2];
	char method[5] = "WS";

	if (!guid_string || !in)
		return AE_BAD_DATA;

	if (!find_guid(guid_string, &wblock))
		return AE_ERROR;

	block = &wblock->gblock;
	handle = wblock->handle;

	if (block->instance_count < instance)
		return AE_BAD_PARAMETER;

	/* Check GUID is a data block */
	if (block->flags & (ACPI_WMI_EVENT | ACPI_WMI_METHOD))
		return AE_ERROR;

	input.count = 2;
	input.pointer = params;
	params[0].type = ACPI_TYPE_INTEGER;
	params[0].integer.value = instance;

	if (block->flags & ACPI_WMI_STRING) {
		params[1].type = ACPI_TYPE_STRING;
	} else {
		params[1].type = ACPI_TYPE_BUFFER;
	}
	params[1].buffer.length = in->length;
	params[1].buffer.pointer = in->pointer;

	strncat(method, block->object_id, 2);

	return acpi_evaluate_object(handle, method, &input, NULL);
}
EXPORT_SYMBOL_GPL(wmi_set_block);

static void wmi_dump_wdg(const struct guid_block *g)
{
	char guid_string[37];

	wmi_gtoa(g->guid, guid_string);

	pr_info("%s:\n", guid_string);
	pr_info("\tobject_id: %c%c\n", g->object_id[0], g->object_id[1]);
	pr_info("\tnotify_id: %02X\n", g->notify_id);
	pr_info("\treserved: %02X\n", g->reserved);
	pr_info("\tinstance_count: %d\n", g->instance_count);
	pr_info("\tflags: %#x ", g->flags);
	if (g->flags) {
		if (g->flags & ACPI_WMI_EXPENSIVE)
			pr_cont("ACPI_WMI_EXPENSIVE ");
		if (g->flags & ACPI_WMI_METHOD)
			pr_cont("ACPI_WMI_METHOD ");
		if (g->flags & ACPI_WMI_STRING)
			pr_cont("ACPI_WMI_STRING ");
		if (g->flags & ACPI_WMI_EVENT)
			pr_cont("ACPI_WMI_EVENT ");
	}
	pr_cont("\n");

}

static void wmi_notify_debug(u32 value, void *context)
{
	struct acpi_buffer response = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object *obj;
	acpi_status status;

	status = wmi_get_event_data(value, &response);
	if (status != AE_OK) {
		pr_info("bad event status 0x%x\n", status);
		return;
	}

	obj = (union acpi_object *)response.pointer;

	if (!obj)
		return;

	pr_info("DEBUG Event ");
	switch(obj->type) {
	case ACPI_TYPE_BUFFER:
		pr_cont("BUFFER_TYPE - length %d\n", obj->buffer.length);
		break;
	case ACPI_TYPE_STRING:
		pr_cont("STRING_TYPE - %s\n", obj->string.pointer);
		break;
	case ACPI_TYPE_INTEGER:
		pr_cont("INTEGER_TYPE - %llu\n", obj->integer.value);
		break;
	case ACPI_TYPE_PACKAGE:
		pr_cont("PACKAGE_TYPE - %d elements\n", obj->package.count);
		break;
	default:
		pr_cont("object type 0x%X\n", obj->type);
	}
	kfree(obj);
}

/**
 * wmi_install_notify_handler - Register handler for WMI events
 * @handler: Function to handle notifications
 * @data: Data to be returned to handler when event is fired
 *
 * Register a handler for events sent to the ACPI-WMI mapper device.
 */
acpi_status wmi_install_notify_handler(const char *guid,
wmi_notify_handler handler, void *data)
{
	struct wmi_block *block;
	acpi_status status;

	if (!guid || !handler)
		return AE_BAD_PARAMETER;

	if (!find_guid(guid, &block))
		return AE_NOT_EXIST;

	if (block->handler && block->handler != wmi_notify_debug)
		return AE_ALREADY_ACQUIRED;

	block->handler = handler;
	block->handler_data = data;

	status = wmi_method_enable(block, 1);

	return status;
}
EXPORT_SYMBOL_GPL(wmi_install_notify_handler);

/**
 * wmi_uninstall_notify_handler - Unregister handler for WMI events
 *
 * Unregister handler for events sent to the ACPI-WMI mapper device.
 */
acpi_status wmi_remove_notify_handler(const char *guid)
{
	struct wmi_block *block;
	acpi_status status = AE_OK;

	if (!guid)
		return AE_BAD_PARAMETER;

	if (!find_guid(guid, &block))
		return AE_NOT_EXIST;

	if (!block->handler || block->handler == wmi_notify_debug)
		return AE_NULL_ENTRY;

	if (debug_event) {
		block->handler = wmi_notify_debug;
	} else {
		status = wmi_method_enable(block, 0);
		block->handler = NULL;
		block->handler_data = NULL;
	}
	return status;
}
EXPORT_SYMBOL_GPL(wmi_remove_notify_handler);

/**
 * wmi_get_event_data - Get WMI data associated with an event
 *
 * @event: Event to find
 * @out: Buffer to hold event data. out->pointer should be freed with kfree()
 *
 * Returns extra data associated with an event in WMI.
 */
acpi_status wmi_get_event_data(u32 event, struct acpi_buffer *out)
{
	struct acpi_object_list input;
	union acpi_object params[1];
	struct guid_block *gblock;
	struct wmi_block *wblock;
	struct list_head *p;

	input.count = 1;
	input.pointer = params;
	params[0].type = ACPI_TYPE_INTEGER;
	params[0].integer.value = event;

	list_for_each(p, &wmi_block_list) {
		wblock = list_entry(p, struct wmi_block, list);
		gblock = &wblock->gblock;

		if ((gblock->flags & ACPI_WMI_EVENT) &&
			(gblock->notify_id == event))
			return acpi_evaluate_object(wblock->handle, "_WED",
				&input, out);
	}

	return AE_NOT_FOUND;
}
EXPORT_SYMBOL_GPL(wmi_get_event_data);

/**
 * wmi_has_guid - Check if a GUID is available
 * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
 *
 * Check if a given GUID is defined by _WDG
 */
bool wmi_has_guid(const char *guid_string)
{
	return find_guid(guid_string, NULL);
}
EXPORT_SYMBOL_GPL(wmi_has_guid);

/*
 * sysfs interface
 */
static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
			     char *buf)
{
	char guid_string[37];
	struct wmi_block *wblock;

	wblock = dev_get_drvdata(dev);
	if (!wblock)
		return -ENOMEM;

	wmi_gtoa(wblock->gblock.guid, guid_string);

	return sprintf(buf, "wmi:%s\n", guid_string);
}

static struct device_attribute wmi_dev_attrs[] = {
	__ATTR_RO(modalias),
	__ATTR_NULL
};

static int wmi_dev_uevent(struct device *dev, struct kobj_uevent_env *env)
{
	char guid_string[37];

	struct wmi_block *wblock;

	if (add_uevent_var(env, "MODALIAS="))
		return -ENOMEM;

	wblock = dev_get_drvdata(dev);
	if (!wblock)
		return -ENOMEM;

	wmi_gtoa(wblock->gblock.guid, guid_string);

	strcpy(&env->buf[env->buflen - 1], "wmi:");
	memcpy(&env->buf[env->buflen - 1 + 4], guid_string, 36);
	env->buflen += 40;

	return 0;
}

static void wmi_dev_free(struct device *dev)
{
	struct wmi_block *wmi_block = container_of(dev, struct wmi_block, dev);

	kfree(wmi_block);
}

static struct class wmi_class = {
	.name = "wmi",
	.dev_release = wmi_dev_free,
	.dev_uevent = wmi_dev_uevent,
	.dev_attrs = wmi_dev_attrs,
};

static struct wmi_block *wmi_create_device(const struct guid_block *gblock,
					   acpi_handle handle)
{
	struct wmi_block *wblock;
	int error;
	char guid_string[37];

	wblock = kzalloc(sizeof(struct wmi_block), GFP_KERNEL);
	if (!wblock) {
		error = -ENOMEM;
		goto err_out;
	}

	wblock->handle = handle;
	wblock->gblock = *gblock;

	wblock->dev.class = &wmi_class;

	wmi_gtoa(gblock->guid, guid_string);
	dev_set_name(&wblock->dev, guid_string);

	dev_set_drvdata(&wblock->dev, wblock);

	error = device_register(&wblock->dev);
	if (error)
		goto err_free;

	list_add_tail(&wblock->list, &wmi_block_list);
	return wblock;

err_free:
	kfree(wblock);
err_out:
	return ERR_PTR(error);
}

static void wmi_free_devices(void)
{
	struct wmi_block *wblock, *next;

	/* Delete devices for all the GUIDs */
	list_for_each_entry_safe(wblock, next, &wmi_block_list, list)
		device_unregister(&wblock->dev);
}

static bool guid_already_parsed(const char *guid_string)
{
	struct wmi_block *wblock;

	list_for_each_entry(wblock, &wmi_block_list, list)
		if (memcmp(wblock->gblock.guid, guid_string, 16) == 0)
			return true;

	return false;
}

/*
 * Parse the _WDG method for the GUID data blocks
 */
static acpi_status parse_wdg(acpi_handle handle)
{
	struct acpi_buffer out = {ACPI_ALLOCATE_BUFFER, NULL};
	union acpi_object *obj;
	const struct guid_block *gblock;
	struct wmi_block *wblock;
	char guid_string[37];
	acpi_status status;
	int retval;
	u32 i, total;

	status = acpi_evaluate_object(handle, "_WDG", NULL, &out);
	if (ACPI_FAILURE(status))
		return -ENXIO;

	obj = (union acpi_object *) out.pointer;
	if (!obj)
		return -ENXIO;

	if (obj->type != ACPI_TYPE_BUFFER) {
		retval = -ENXIO;
		goto out_free_pointer;
	}

	gblock = (const struct guid_block *)obj->buffer.pointer;
	total = obj->buffer.length / sizeof(struct guid_block);

	for (i = 0; i < total; i++) {
		/*
		  Some WMI devices, like those for nVidia hooks, have a
		  duplicate GUID. It's not clear what we should do in this
		  case yet, so for now, we'll just ignore the duplicate.
		  Anyone who wants to add support for that device can come
		  up with a better workaround for the mess then.
		*/
		if (guid_already_parsed(gblock[i].guid) == true) {
			wmi_gtoa(gblock[i].guid, guid_string);
			pr_info("Skipping duplicate GUID %s\n", guid_string);
			continue;
		}

		if (debug_dump_wdg)
			wmi_dump_wdg(&gblock[i]);

		wblock = wmi_create_device(&gblock[i], handle);
		if (IS_ERR(wblock)) {
			retval = PTR_ERR(wblock);
			wmi_free_devices();
			break;
		}

		if (debug_event) {
			wblock->handler = wmi_notify_debug;
			wmi_method_enable(wblock, 1);
		}
	}

	retval = 0;

out_free_pointer:
	kfree(out.pointer);

	return retval;
}

/*
 * WMI can have EmbeddedControl access regions. In which case, we just want to
 * hand these off to the EC driver.
 */
static acpi_status
acpi_wmi_ec_space_handler(u32 function, acpi_physical_address address,
		      u32 bits, u64 *value,
		      void *handler_context, void *region_context)
{
	int result = 0, i = 0;
	u8 temp = 0;

	if ((address > 0xFF) || !value)
		return AE_BAD_PARAMETER;

	if (function != ACPI_READ && function != ACPI_WRITE)
		return AE_BAD_PARAMETER;

	if (bits != 8)
		return AE_BAD_PARAMETER;

	if (function == ACPI_READ) {
		result = ec_read(address, &temp);
		(*value) |= ((u64)temp) << i;
	} else {
		temp = 0xff & ((*value) >> i);
		result = ec_write(address, temp);
	}

	switch (result) {
	case -EINVAL:
		return AE_BAD_PARAMETER;
		break;
	case -ENODEV:
		return AE_NOT_FOUND;
		break;
	case -ETIME:
		return AE_TIME;
		break;
	default:
		return AE_OK;
	}
}

static void acpi_wmi_notify(struct acpi_device *device, u32 event)
{
	struct guid_block *block;
	struct wmi_block *wblock;
	struct list_head *p;
	char guid_string[37];

	list_for_each(p, &wmi_block_list) {
		wblock = list_entry(p, struct wmi_block, list);
		block = &wblock->gblock;

		if ((block->flags & ACPI_WMI_EVENT) &&
			(block->notify_id == event)) {
			if (wblock->handler)
				wblock->handler(event, wblock->handler_data);
			if (debug_event) {
				wmi_gtoa(wblock->gblock.guid, guid_string);
				pr_info("DEBUG Event GUID: %s\n", guid_string);
			}

			acpi_bus_generate_netlink_event(
				device->pnp.device_class, dev_name(&device->dev),
				event, 0);
			break;
		}
	}
}

static int acpi_wmi_remove(struct acpi_device *device, int type)
{
	acpi_remove_address_space_handler(device->handle,
				ACPI_ADR_SPACE_EC, &acpi_wmi_ec_space_handler);
	wmi_free_devices();

	return 0;
}

static int acpi_wmi_add(struct acpi_device *device)
{
	acpi_status status;
	int error;

	status = acpi_install_address_space_handler(device->handle,
						    ACPI_ADR_SPACE_EC,
						    &acpi_wmi_ec_space_handler,
						    NULL, NULL);
	if (ACPI_FAILURE(status)) {
		pr_err("Error installing EC region handler\n");
		return -ENODEV;
	}

	error = parse_wdg(device->handle);
	if (error) {
		acpi_remove_address_space_handler(device->handle,
						  ACPI_ADR_SPACE_EC,
						  &acpi_wmi_ec_space_handler);
		pr_err("Failed to parse WDG method\n");
		return error;
	}

	return 0;
}

static int __init acpi_wmi_init(void)
{
	int error;

	if (acpi_disabled)
		return -ENODEV;

	error = class_register(&wmi_class);
	if (error)
		return error;

	error = acpi_bus_register_driver(&acpi_wmi_driver);
	if (error) {
		pr_err("Error loading mapper\n");
		class_unregister(&wmi_class);
		return error;
	}

	pr_info("Mapper loaded\n");
	return 0;
}

static void __exit acpi_wmi_exit(void)
{
	acpi_bus_unregister_driver(&acpi_wmi_driver);
	class_unregister(&wmi_class);

	pr_info("Mapper unloaded\n");
}

subsys_initcall(acpi_wmi_init);
module_exit(acpi_wmi_exit);