ACPI: WMI: Add ACPI-WMI mapping driver

The following is an implementation of the Windows Management
Instrumentation (WMI) ACPI interface mapper (PNP0C14).

What it does:

Parses the _WDG method and exports functions to process WMI method calls,
data block query/ set commands (both based on GUID) and does basic event
handling.

How: WMI presents an in kernel interface here (essentially, a minimal
wrapper around ACPI)

(const char *guid assume the 36 character ASCII representation of
a GUID - e.g. 67C3371D-95A3-4C37-BB61-DD47B491DAAB)

wmi_evaluate_method(const char *guid, u8 instance, u32 method_id,
const struct acpi_buffer *in, struct acpi_buffer *out)

wmi_query_block(const char *guid, u8 instance,
struct acpi_buffer *out)

wmi_set_block(const char *guid, u38 instance,
const struct acpi_buffer *in)

wmi_install_notify_handler(acpi_notify_handler handler);

wmi_remove_notify_handler(void);

wmi_get_event_data(u32 event, struct acpi_buffer *out)

wmi_has_guid(const char guid*)

wmi_has_guid() is a helper function to find if a GUID exists or not on the
system (a quick and easy way for WMI dependant drivers to see if the
the method/ block they want exists, since GUIDs are supposed to be unique).

Event handling - allow a WMI based driver to register a notifier handler
for each GUID with WMI. When a notification is sent to a GUID in WMI, the
handler registered with WMI is then called (it is left to the caller to
ask for the WMI event data associated with the GUID, if needed).

What it won't do:

Unicode - The MS article[1] calls for converting between ASCII and Unicode (or
vice versa) if a GUID is marked as "string". This is left up to the calling
driver.

Handle a MOF[1] - the WMI mapper just exports methods, data and events to
userspace. MOF handling is down to userspace.

Userspace interface - this will be added later.

[1] http://www.microsoft.com/whdc/system/pnppwr/wmi/wmi-acpi.mspx

===
ChangeLog
==

v1 (2007-10-02):

* Initial release

v2 (2007-10-05):

* Cleaned up code - split up super "wmi_evaluate_block" -> each external
  symbol now handles its own ACPI calls, rather than handing off to
  a "super" method (and in turn, is a lot simpler to read)
* Added a find_guid() symbol - return true if a given GUID exists on
  the system
* wmi_* functions now return type acpi_status (since they are just
  fancy wrappers around acpi_evaluate_object())
* Removed extra debug code

v3 (2007-10-27)

* More code clean up - now passes checkpatch.pl
* Change data block calls - ref MS spec, method ID is not required for
  them, so drop it from the function parameters.
* Const'ify guid in the function call parameters.
* Fix _WDG buffer handling - copy the data to our own private structure.
* Change WMI from tristate to bool - otherwise the external functions are
  not exported in linux/acpi.h if you try to build WMI as a module.
* Fix more flag comparisons.
* Add a maintainers entry - since I wrote this, I should take the blame
  for it.

v4 (2007-10-30)

* Add missing brace from after fixing checkpatch errors.
* Rewrote event handling - allow external drivers to register with WMI to
  handle WMI events
* Clean up flags and sanitise flag handling

v5 (2007-11-03)

* Add sysfs interface for userspace. Export events over netlink again.
* Remove module left overs, fully convert to built-in driver.
* Tweak in-kernel API to use u8 for instance, since this is what the GUID
  blocks use (so instance cannot be greater than u8).
* Export wmi_get_event_data() for in kernel WMI drivers.

v6 (2007-11-07)

* Split out userspace into a different patch

v7 (2007-11-20)

* Fix driver to handle multiple PNP0C14 devices - store all GUIDs using
  the kernel's built in list functions, and just keep adding to the list
  every time we handle a PNP0C14 devices - GUIDs will always be unique,
  and WMI callers do not know or care about different devices.
* Change WMI event handler registration to use its' own event handling
  struct; we should not pass an acpi_handle down to any WMI based drivers
  - they should be able to function with only the calls provided in WMI.
* Update my e-mail address

v8 (2007-11-28)

* Convert back to a module.
* Update Kconfig to default to building as a module.
* Remove an erroneous printk.
* Simply comments for string flag (since we now leave the handling to the
  caller).

v9 (2007-12-07)

* Add back missing MODULE_DEVICE_TABLE for autoloading
* Checkpatch fixes

v10 (2007-12-12)

* Workaround broken GUIDs declared expensive without a WCxx method.
* Minor cleanups

v11 (2007-12-17)

* More fixing for broken GUIDs declared expensive without a WCxx method.
* Add basic EmbeddedControl region handling.

v12 (2007-12-18)

* Changed EC region handling code, as per Alexey's comments.

v13 (2007-12-27)

* Changed event handling so that we can have one event handler registered
  per GUID, as per Matthew Garrett's suggestion.

v14 (2008-01-12)

* Remove ACPI debug statements

v15 (2008-02-01)

* Replace two remaining 'x == NULL' type tests with '!x'

v16 (2008-02-05)

* Change MAINTAINERS entry, as I am not, and never have been, paid to work
  on WMI
* Remove 'default' line from Kconfig

Signed-off-by: Carlos Corbacho <carlos@strangeworlds.co.uk>
CC: Matthew Garrett <mjg59@srcf.ucam.org>
CC: Alexey Starikovskiy <aystarik@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>

MAINTAINERS

@@ -252,6 +252,13 @@ L:	linux-acpi@vger.kernel.org
 W:	http://acpi.sourceforge.net/
 S:	Supported
 
+ACPI WMI DRIVER
+P:      Carlos Corbacho
+M:      carlos@strangeworlds.co.uk
+L:      linux-acpi@vger.kernel.org
+W:      http://www.lesswatts.org/projects/acpi/
+S:      Maintained
+
 ADM1025 HARDWARE MONITOR DRIVER
 P:	Jean Delvare
 M:	khali@linux-fr.org

drivers/acpi/Kconfig

@@ -199,6 +199,16 @@ config ACPI_NUMA
 	depends on (X86 || IA64)
 	default y if IA64_GENERIC || IA64_SGI_SN2
 
+config ACPI_WMI
+	tristate "WMI (EXPERIMENTAL)"
+	depends on EXPERIMENTAL
+	help
+	  This driver adds support for the ACPI-WMI mapper device (PNP0C14)
+	  found on some systems.
+
+	  NOTE: You will need another driver or userspace application on top of
+	  this to actually use anything defined in the ACPI-WMI mapper.
+
 config ACPI_ASUS
         tristate "ASUS/Medion Laptop Extras"
 	depends on X86

drivers/acpi/Makefile

@@ -55,6 +55,7 @@ obj-$(CONFIG_ACPI_THERMAL)	+= thermal.o
 obj-$(CONFIG_ACPI_SYSTEM)	+= system.o event.o
 obj-$(CONFIG_ACPI_DEBUG)	+= debug.o
 obj-$(CONFIG_ACPI_NUMA)		+= numa.o
+obj-$(CONFIG_ACPI_WMI)		+= wmi.o
 obj-$(CONFIG_ACPI_ASUS)		+= asus_acpi.o
 obj-$(CONFIG_ACPI_TOSHIBA)	+= toshiba_acpi.o
 obj-$(CONFIG_ACPI_HOTPLUG_MEMORY)	+= acpi_memhotplug.o

drivers/acpi/wmi.c

@@ -0,0 +1,710 @@
+/*
+ *  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.
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/acpi.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"
+
+#undef PREFIX
+#define PREFIX "ACPI: WMI: "
+
+static DEFINE_MUTEX(wmi_data_lock);
+
+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;
+};
+
+static struct wmi_block wmi_blocks;
+
+/*
+ * 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 acpi_wmi_remove(struct acpi_device *device, int type);
+static int acpi_wmi_add(struct acpi_device *device);
+
+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,
+		},
+};
+
+/*
+ * 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)
+{
+	unsigned int x; /* For correct wrapping */
+	int h;
+
+	/* high part */
+	x = src[0];
+	if (x - '0' <= '9' - '0') {
+		h = x - '0';
+	} else if (x - 'a' <= 'f' - 'a') {
+		h = x - 'a' + 10;
+	} else if (x - 'A' <= 'F' - 'A') {
+		h = x - 'A' + 10;
+	} else {
+		return -1;
+	}
+	h <<= 4;
+
+	/* low part */
+	x = src[1];
+	if (x - '0' <= '9' - '0')
+		return h | (x - '0');
+	if (x - 'a' <= 'f' - 'a')
+		return h | (x - 'a' + 10);
+	if (x - 'A' <= 'F' - 'A')
+		return h | (x - 'A' + 10);
+	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;
+}
+
+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_blocks.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;
+}
+
+/*
+ * 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[4] = "WM";
+
+	if (!find_guid(guid_string, &wblock))
+		return AE_BAD_ADDRESS;
+
+	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;
+	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[4];
+	char wc_method[4] = "WC";
+
+	if (!guid_string || !out)
+		return AE_BAD_PARAMETER;
+
+	if (!find_guid(guid_string, &wblock))
+		return AE_BAD_ADDRESS;
+
+	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_BAD_ADDRESS;
+
+	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_evaluate_object(handle, wc_method,
+			&wc_input, NULL);
+	}
+
+	strcpy(method, "WQ");
+	strncat(method, block->object_id, 2);
+
+	status = acpi_evaluate_object(handle, method, NULL, 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) && 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[4] = "WS";
+
+	if (!guid_string || !in)
+		return AE_BAD_DATA;
+
+	if (!find_guid(guid_string, &wblock))
+		return AE_BAD_ADDRESS;
+
+	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_BAD_ADDRESS;
+
+	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);
+
+/**
+ * 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;
+
+	if (!guid || !handler)
+		return AE_BAD_PARAMETER;
+
+	find_guid(guid, &block);
+	if (!block)
+		return AE_NOT_EXIST;
+
+	if (block->handler)
+		return AE_ALREADY_ACQUIRED;
+
+	block->handler = handler;
+	block->handler_data = data;
+
+	return AE_OK;
+}
+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;
+
+	if (!guid)
+		return AE_BAD_PARAMETER;
+
+	find_guid(guid, &block);
+	if (!block)
+		return AE_NOT_EXIST;
+
+	if (!block->handler)
+		return AE_NULL_ENTRY;
+
+	block->handler = NULL;
+	block->handler_data = NULL;
+
+	return AE_OK;
+}
+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
+ *
+ * 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_blocks.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);
+
+/*
+ * Parse the _WDG method for the GUID data blocks
+ */
+static __init acpi_status parse_wdg(acpi_handle handle)
+{
+	struct acpi_buffer out = {ACPI_ALLOCATE_BUFFER, NULL};
+	union acpi_object *obj;
+	struct guid_block *gblock;
+	struct wmi_block *wblock;
+	acpi_status status;
+	u32 i, total;
+
+	status = acpi_evaluate_object(handle, "_WDG", NULL, &out);
+
+	if (ACPI_FAILURE(status))
+		return status;
+
+	obj = (union acpi_object *) out.pointer;
+
+	if (obj->type != ACPI_TYPE_BUFFER)
+		return AE_ERROR;
+
+	total = obj->buffer.length / sizeof(struct guid_block);
+
+	gblock = kzalloc(obj->buffer.length, GFP_KERNEL);
+	if (!gblock)
+		return AE_NO_MEMORY;
+
+	memcpy(gblock, obj->buffer.pointer, obj->buffer.length);
+
+	for (i = 0; i < total; i++) {
+		wblock = kzalloc(sizeof(struct wmi_block), GFP_KERNEL);
+		if (!wblock)
+			return AE_NO_MEMORY;
+
+		wblock->gblock = gblock[i];
+		wblock->handle = handle;
+		list_add_tail(&wblock->list, &wmi_blocks.list);
+	}
+
+	kfree(out.pointer);
+	kfree(gblock);
+
+	return status;
+}
+
+/*
+ * 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, acpi_integer * 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) |= ((acpi_integer)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(acpi_handle handle, u32 event, void *data)
+{
+	struct guid_block *block;
+	struct wmi_block *wblock;
+	struct list_head *p;
+	struct acpi_device *device = data;
+
+	list_for_each(p, &wmi_blocks.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);
+
+			acpi_bus_generate_netlink_event(
+				device->pnp.device_class, device->dev.bus_id,
+				event, 0);
+			break;
+		}
+	}
+}
+
+static int acpi_wmi_remove(struct acpi_device *device, int type)
+{
+	acpi_remove_notify_handler(device->handle, ACPI_DEVICE_NOTIFY,
+		acpi_wmi_notify);
+
+	acpi_remove_address_space_handler(device->handle,
+				ACPI_ADR_SPACE_EC, &acpi_wmi_ec_space_handler);
+
+	return 0;
+}
+
+static int __init acpi_wmi_add(struct acpi_device *device)
+{
+	acpi_status status;
+	int result = 0;
+
+	status = acpi_install_notify_handler(device->handle, ACPI_DEVICE_NOTIFY,
+		acpi_wmi_notify, device);
+	if (ACPI_FAILURE(status)) {
+		printk(KERN_ERR PREFIX "Error installing notify handler\n");
+		return -ENODEV;
+	}
+
+	status = acpi_install_address_space_handler(device->handle,
+						    ACPI_ADR_SPACE_EC,
+						    &acpi_wmi_ec_space_handler,
+						    NULL, NULL);
+	if (ACPI_FAILURE(status))
+		return -ENODEV;
+
+	status = parse_wdg(device->handle);
+	if (ACPI_FAILURE(status)) {
+		printk(KERN_ERR PREFIX "Error installing EC region handler\n");
+		return -ENODEV;
+	}
+
+	return result;
+}
+
+static int __init acpi_wmi_init(void)
+{
+	acpi_status result;
+
+	if (acpi_disabled)
+		return -ENODEV;
+
+	INIT_LIST_HEAD(&wmi_blocks.list);
+
+	result = acpi_bus_register_driver(&acpi_wmi_driver);
+
+	if (result < 0) {
+		printk(KERN_INFO PREFIX "Error loading mapper\n");
+	} else {
+		printk(KERN_INFO PREFIX "Mapper loaded\n");
+	}
+
+	return result;
+}
+
+static void __exit acpi_wmi_exit(void)
+{
+	struct list_head *p, *tmp;
+	struct wmi_block *wblock;
+
+	acpi_bus_unregister_driver(&acpi_wmi_driver);
+
+	list_for_each_safe(p, tmp, &wmi_blocks.list) {
+		wblock = list_entry(p, struct wmi_block, list);
+
+		list_del(p);
+		kfree(wblock);
+	}
+
+	printk(KERN_INFO PREFIX "Mapper unloaded\n");
+}
+
+subsys_initcall(acpi_wmi_init);
+module_exit(acpi_wmi_exit);

include/linux/acpi.h

@@ -192,6 +192,26 @@ extern int ec_transaction(u8 command,
 
 #endif /*CONFIG_ACPI_EC*/
 
+#if defined(CONFIG_ACPI_WMI) || defined(CONFIG_ACPI_WMI_MODULE)
+
+typedef void (*wmi_notify_handler) (u32 value, void *context);
+
+extern acpi_status wmi_evaluate_method(const char *guid, u8 instance,
+					u32 method_id,
+					const struct acpi_buffer *in,
+					struct acpi_buffer *out);
+extern acpi_status wmi_query_block(const char *guid, u8 instance,
+					struct acpi_buffer *out);
+extern acpi_status wmi_set_block(const char *guid, u8 instance,
+					const struct acpi_buffer *in);
+extern acpi_status wmi_install_notify_handler(const char *guid,
+					wmi_notify_handler handler, void *data);
+extern acpi_status wmi_remove_notify_handler(const char *guid);
+extern acpi_status wmi_get_event_data(u32 event, struct acpi_buffer *out);
+extern bool wmi_has_guid(const char *guid);
+
+#endif	/* CONFIG_ACPI_WMI */
+
 extern int acpi_blacklisted(void);
 #ifdef CONFIG_DMI
 extern void acpi_dmi_osi_linux(int enable, const struct dmi_system_id *d);