/*

   *  video.c - ACPI Video Driver

   *
   *  Copyright (C) 2004 Luming Yu <luming.yu@intel.com>
   *  Copyright (C) 2004 Bruno Ducrot <ducrot@poupinou.org>

   *  Copyright (C) 2006 Thomas Tuttle <linux-kernel@ttuttle.net>

   *
   * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   *
   *  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/list.h>

  #include <linux/mutex.h>

  #include <linux/input.h>

  #include <linux/backlight.h>

  #include <linux/thermal.h>

  #include <linux/sort.h>

  #include <linux/pci.h>
  #include <linux/pci_ids.h>

  #include <linux/slab.h>

  #include <linux/dmi.h>

  #include <linux/suspend.h>

  #include <linux/acpi.h>

  #include <acpi/video.h>

  #include <asm/uaccess.h>

  #include "internal.h"

  #define ACPI_VIDEO_BUS_NAME		"Video Bus"
  #define ACPI_VIDEO_DEVICE_NAME		"Video Device"
  #define ACPI_VIDEO_NOTIFY_SWITCH	0x80
  #define ACPI_VIDEO_NOTIFY_PROBE		0x81
  #define ACPI_VIDEO_NOTIFY_CYCLE		0x82
  #define ACPI_VIDEO_NOTIFY_NEXT_OUTPUT	0x83
  #define ACPI_VIDEO_NOTIFY_PREV_OUTPUT	0x84

  #define ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS	0x85
  #define	ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS	0x86
  #define ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS	0x87
  #define ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS	0x88
  #define ACPI_VIDEO_NOTIFY_DISPLAY_OFF		0x89

  #define MAX_NAME_LEN	20

  #define _COMPONENT		ACPI_VIDEO_COMPONENT

  ACPI_MODULE_NAME("video");

  MODULE_AUTHOR("Bruno Ducrot");

  MODULE_DESCRIPTION("ACPI Video Driver");

  MODULE_LICENSE("GPL");

  static bool brightness_switch_enabled = 1;

  module_param(brightness_switch_enabled, bool, 0644);

  /*
   * By default, we don't allow duplicate ACPI video bus devices
   * under the same VGA controller
   */

  static bool allow_duplicates;

  module_param(allow_duplicates, bool, 0644);

  /*

   * For Windows 8 systems: used to decide if video module
   * should skip registering backlight interface of its own.

   */

  static int use_native_backlight_param = -1;

  module_param_named(use_native_backlight, use_native_backlight_param, int, 0444);

  static bool use_native_backlight_dmi = true;

  static int register_count;

  static struct mutex video_list_lock;
  static struct list_head video_bus_head;

  static int acpi_video_bus_add(struct acpi_device *device);

  static int acpi_video_bus_remove(struct acpi_device *device);

  static void acpi_video_bus_notify(struct acpi_device *device, u32 event);

  static const struct acpi_device_id video_device_ids[] = {
  	{ACPI_VIDEO_HID, 0},
  	{"", 0},
  };
  MODULE_DEVICE_TABLE(acpi, video_device_ids);

  static struct acpi_driver acpi_video_bus = {

  	.name = "video",

  	.class = ACPI_VIDEO_CLASS,

  	.ids = video_device_ids,

  	.ops = {
  		.add = acpi_video_bus_add,
  		.remove = acpi_video_bus_remove,

  		.notify = acpi_video_bus_notify,

  		},

  };
  
  struct acpi_video_bus_flags {

  	u8 multihead:1;		/* can switch video heads */
  	u8 rom:1;		/* can retrieve a video rom */
  	u8 post:1;		/* can configure the head to */
  	u8 reserved:5;

  };
  
  struct acpi_video_bus_cap {

  	u8 _DOS:1;		/* Enable/Disable output switching */
  	u8 _DOD:1;		/* Enumerate all devices attached to display adapter */
  	u8 _ROM:1;		/* Get ROM Data */
  	u8 _GPD:1;		/* Get POST Device */
  	u8 _SPD:1;		/* Set POST Device */
  	u8 _VPO:1;		/* Video POST Options */

  	u8 reserved:2;

  };

  struct acpi_video_device_attrib {
  	u32 display_index:4;	/* A zero-based instance of the Display */

  	u32 display_port_attachment:4;	/* This field differentiates the display type */
  	u32 display_type:4;	/* Describe the specific type in use */
  	u32 vendor_specific:4;	/* Chipset Vendor Specific */
  	u32 bios_can_detect:1;	/* BIOS can detect the device */
  	u32 depend_on_vga:1;	/* Non-VGA output device whose power is related to

  				   the VGA device. */

  	u32 pipe_id:3;		/* For VGA multiple-head devices. */
  	u32 reserved:10;	/* Must be 0 */
  	u32 device_id_scheme:1;	/* Device ID Scheme */

  };
  
  struct acpi_video_enumerated_device {
  	union {
  		u32 int_val;

  		struct acpi_video_device_attrib attrib;

  	} value;
  	struct acpi_video_device *bind_info;
  };
  
  struct acpi_video_bus {

  	struct acpi_device *device;

  	bool backlight_registered;

  	bool backlight_notifier_registered;

  	u8 dos_setting;

  	struct acpi_video_enumerated_device *attached_array;

  	u8 attached_count;

  	u8 child_count;

  	struct acpi_video_bus_cap cap;

  	struct acpi_video_bus_flags flags;

  	struct list_head video_device_list;

  	struct mutex device_list_lock;	/* protects video_device_list */

  	struct list_head entry;

  	struct input_dev *input;
  	char phys[32];	/* for input device */

  	struct notifier_block pm_nb;

  	struct notifier_block backlight_nb;

  };
  
  struct acpi_video_device_flags {

  	u8 crt:1;
  	u8 lcd:1;
  	u8 tvout:1;

  	u8 dvi:1;

  	u8 bios:1;
  	u8 unknown:1;

  	u8 notify:1;
  	u8 reserved:1;

  };
  
  struct acpi_video_device_cap {

  	u8 _ADR:1;		/* Return the unique ID */
  	u8 _BCL:1;		/* Query list of brightness control levels supported */
  	u8 _BCM:1;		/* Set the brightness level */

  	u8 _BQC:1;		/* Get current brightness level */

  	u8 _BCQ:1;		/* Some buggy BIOS uses _BCQ instead of _BQC */

  	u8 _DDC:1;		/* Return the EDID for this device */

  };

  struct acpi_video_brightness_flags {
  	u8 _BCL_no_ac_battery_levels:1;	/* no AC/Battery levels in _BCL */

  	u8 _BCL_reversed:1;		/* _BCL package is in a reversed order */

  	u8 _BQC_use_index:1;		/* _BQC returns an index value */

  };

  struct acpi_video_device_brightness {

  	int curr;
  	int count;
  	int *levels;

  	struct acpi_video_brightness_flags flags;

  };
  
  struct acpi_video_device {

  	unsigned long device_id;
  	struct acpi_video_device_flags flags;
  	struct acpi_video_device_cap cap;
  	struct list_head entry;

  	struct delayed_work switch_brightness_work;
  	int switch_brightness_event;

  	struct acpi_video_bus *video;
  	struct acpi_device *dev;

  	struct acpi_video_device_brightness *brightness;

  	struct backlight_device *backlight;

  	struct thermal_cooling_device *cooling_dev;

  };

  static const char device_decode[][30] = {

  	"motherboard VGA device",
  	"PCI VGA device",
  	"AGP VGA device",
  	"UNKNOWN",
  };

  static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data);
  static void acpi_video_device_rebind(struct acpi_video_bus *video);
  static void acpi_video_device_bind(struct acpi_video_bus *video,
  				   struct acpi_video_device *device);

  static int acpi_video_device_enumerate(struct acpi_video_bus *video);

  static int acpi_video_device_lcd_set_level(struct acpi_video_device *device,
  			int level);
  static int acpi_video_device_lcd_get_level_current(
  			struct acpi_video_device *device,

  			unsigned long long *level, bool raw);

  static int acpi_video_get_next_level(struct acpi_video_device *device,
  				     u32 level_current, u32 event);

  static void acpi_video_switch_brightness(struct work_struct *work);

  static bool acpi_video_use_native_backlight(void)
  {
  	if (use_native_backlight_param != -1)
  		return use_native_backlight_param;
  	else
  		return use_native_backlight_dmi;
  }

  bool acpi_video_verify_backlight_support(void)

  {

  	if (acpi_osi_is_win8() && acpi_video_use_native_backlight() &&

  	    backlight_device_registered(BACKLIGHT_RAW))
  		return false;
  	return acpi_video_backlight_support();
  }

  EXPORT_SYMBOL_GPL(acpi_video_verify_backlight_support);

  /* backlight device sysfs support */

  static int acpi_video_get_brightness(struct backlight_device *bd)
  {

  	unsigned long long cur_level;

  	int i;

  	struct acpi_video_device *vd = bl_get_data(bd);

  	if (acpi_video_device_lcd_get_level_current(vd, &cur_level, false))

  		return -EINVAL;

  	for (i = 2; i < vd->brightness->count; i++) {
  		if (vd->brightness->levels[i] == cur_level)

  			/*
  			 * The first two entries are special - see page 575
  			 * of the ACPI spec 3.0
  			 */

  			return i - 2;

  	}
  	return 0;

  }
  
  static int acpi_video_set_brightness(struct backlight_device *bd)
  {

  	int request_level = bd->props.brightness + 2;

  	struct acpi_video_device *vd = bl_get_data(bd);

  	cancel_delayed_work(&vd->switch_brightness_work);

  	return acpi_video_device_lcd_set_level(vd,
  				vd->brightness->levels[request_level]);

  }

  static const struct backlight_ops acpi_backlight_ops = {

  	.get_brightness = acpi_video_get_brightness,
  	.update_status  = acpi_video_set_brightness,
  };

  /* thermal cooling device callbacks */

  static int video_get_max_state(struct thermal_cooling_device *cooling_dev, unsigned

  			       long *state)

  {

  	struct acpi_device *device = cooling_dev->devdata;

  	struct acpi_video_device *video = acpi_driver_data(device);

  	*state = video->brightness->count - 3;
  	return 0;

  }

  static int video_get_cur_state(struct thermal_cooling_device *cooling_dev, unsigned

  			       long *state)

  {

  	struct acpi_device *device = cooling_dev->devdata;

  	struct acpi_video_device *video = acpi_driver_data(device);

  	unsigned long long level;

  	int offset;

  	if (acpi_video_device_lcd_get_level_current(video, &level, false))

  		return -EINVAL;

  	for (offset = 2; offset < video->brightness->count; offset++)
  		if (level == video->brightness->levels[offset]) {
  			*state = video->brightness->count - offset - 1;
  			return 0;
  		}

  
  	return -EINVAL;
  }
  
  static int

  video_set_cur_state(struct thermal_cooling_device *cooling_dev, unsigned long state)

  {

  	struct acpi_device *device = cooling_dev->devdata;

  	struct acpi_video_device *video = acpi_driver_data(device);
  	int level;

  	if (state >= video->brightness->count - 2)

  		return -EINVAL;
  
  	state = video->brightness->count - state;

  	level = video->brightness->levels[state - 1];

  	return acpi_video_device_lcd_set_level(video, level);
  }

  static const struct thermal_cooling_device_ops video_cooling_ops = {

  	.get_max_state = video_get_max_state,
  	.get_cur_state = video_get_cur_state,
  	.set_cur_state = video_set_cur_state,
  };

  /*
   * --------------------------------------------------------------------------
   *                             Video Management
   * --------------------------------------------------------------------------
   */

  static int

  acpi_video_device_lcd_query_levels(struct acpi_video_device *device,
  				   union acpi_object **levels)

  {

  	int status;
  	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
  	union acpi_object *obj;

  
  	*levels = NULL;

  	status = acpi_evaluate_object(device->dev->handle, "_BCL", NULL, &buffer);

  	if (!ACPI_SUCCESS(status))

  		return status;

  	obj = (union acpi_object *)buffer.pointer;

  	if (!obj || (obj->type != ACPI_TYPE_PACKAGE)) {

  		printk(KERN_ERR PREFIX "Invalid _BCL data
  ");

  		status = -EFAULT;
  		goto err;
  	}
  
  	*levels = obj;

  	return 0;

  err:

  	kfree(buffer.pointer);

  	return status;

  }
  
  static int

  acpi_video_device_lcd_set_level(struct acpi_video_device *device, int level)

  {

  	int status;

  	int state;

  	status = acpi_execute_simple_method(device->dev->handle,
  					    "_BCM", level);

  	if (ACPI_FAILURE(status)) {
  		ACPI_ERROR((AE_INFO, "Evaluating _BCM failed"));
  		return -EIO;
  	}

  	device->brightness->curr = level;

  	for (state = 2; state < device->brightness->count; state++)

  		if (level == device->brightness->levels[state]) {

  			if (device->backlight)
  				device->backlight->props.brightness = state - 2;

  			return 0;
  		}

  	ACPI_ERROR((AE_INFO, "Current brightness invalid"));
  	return -EINVAL;

  }

  /*
   * For some buggy _BQC methods, we need to add a constant value to
   * the _BQC return value to get the actual current brightness level
   */
  
  static int bqc_offset_aml_bug_workaround;
  static int __init video_set_bqc_offset(const struct dmi_system_id *d)
  {
  	bqc_offset_aml_bug_workaround = 9;
  	return 0;
  }

  static int __init video_disable_native_backlight(const struct dmi_system_id *d)
  {
  	use_native_backlight_dmi = false;
  	return 0;
  }

  static struct dmi_system_id video_dmi_table[] __initdata = {
  	/*
  	 * Broken _BQC workaround http://bugzilla.kernel.org/show_bug.cgi?id=13121
  	 */
  	{
  	 .callback = video_set_bqc_offset,
  	 .ident = "Acer Aspire 5720",
  	 .matches = {
  		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
  		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5720"),
  		},
  	},

  	{
  	 .callback = video_set_bqc_offset,
  	 .ident = "Acer Aspire 5710Z",
  	 .matches = {
  		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
  		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5710Z"),
  		},
  	},

  	{
  	 .callback = video_set_bqc_offset,
  	 .ident = "eMachines E510",
  	 .matches = {
  		DMI_MATCH(DMI_BOARD_VENDOR, "EMACHINES"),
  		DMI_MATCH(DMI_PRODUCT_NAME, "eMachines E510"),
  		},
  	},

  	{
  	 .callback = video_set_bqc_offset,
  	 .ident = "Acer Aspire 5315",
  	 .matches = {
  		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
  		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5315"),
  		},
  	},

  	{
  	 .callback = video_set_bqc_offset,
  	 .ident = "Acer Aspire 7720",
  	 .matches = {
  		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
  		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 7720"),
  		},
  	},

  
  	/*
  	 * These models have a working acpi_video backlight control, and using
  	 * native backlight causes a regression where backlight does not work
  	 * when userspace is not handling brightness key events. Disable
  	 * native_backlight on these to fix this:
  	 * https://bugzilla.kernel.org/show_bug.cgi?id=81691
  	 */
  	{
  	 .callback = video_disable_native_backlight,
  	 .ident = "ThinkPad T420",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
  		DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T420"),
  		},
  	},
  	{
  	 .callback = video_disable_native_backlight,
  	 .ident = "ThinkPad T520",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
  		DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T520"),
  		},
  	},

  	{
  	 .callback = video_disable_native_backlight,
  	 .ident = "ThinkPad X201s",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
  		DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X201s"),
  		},
  	},

  
  	/* The native backlight controls do not work on some older machines */
  	{
  	 /* https://bugs.freedesktop.org/show_bug.cgi?id=81515 */
  	 .callback = video_disable_native_backlight,
  	 .ident = "HP ENVY 15 Notebook",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
  		DMI_MATCH(DMI_PRODUCT_NAME, "HP ENVY 15 Notebook PC"),
  		},
  	},

  
  	{
  	 .callback = video_disable_native_backlight,
  	 .ident = "SAMSUNG 870Z5E/880Z5E/680Z5E",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
  		DMI_MATCH(DMI_PRODUCT_NAME, "870Z5E/880Z5E/680Z5E"),
  		},
  	},
  	{
  	 .callback = video_disable_native_backlight,
  	 .ident = "SAMSUNG 370R4E/370R4V/370R5E/3570RE/370R5V",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
  		DMI_MATCH(DMI_PRODUCT_NAME, "370R4E/370R4V/370R5E/3570RE/370R5V"),
  		},
  	},

  	{}
  };

  static unsigned long long
  acpi_video_bqc_value_to_level(struct acpi_video_device *device,
  			      unsigned long long bqc_value)
  {
  	unsigned long long level;
  
  	if (device->brightness->flags._BQC_use_index) {
  		/*
  		 * _BQC returns an index that doesn't account for
  		 * the first 2 items with special meaning, so we need
  		 * to compensate for that by offsetting ourselves
  		 */
  		if (device->brightness->flags._BCL_reversed)
  			bqc_value = device->brightness->count - 3 - bqc_value;
  
  		level = device->brightness->levels[bqc_value + 2];
  	} else {
  		level = bqc_value;
  	}
  
  	level += bqc_offset_aml_bug_workaround;
  
  	return level;
  }

  static int

  acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,

  					unsigned long long *level, bool raw)

  {

  	acpi_status status = AE_OK;

  	int i;

  	if (device->cap._BQC || device->cap._BCQ) {
  		char *buf = device->cap._BQC ? "_BQC" : "_BCQ";
  
  		status = acpi_evaluate_integer(device->dev->handle, buf,

  						NULL, level);
  		if (ACPI_SUCCESS(status)) {

  			if (raw) {
  				/*
  				 * Caller has indicated he wants the raw
  				 * value returned by _BQC, so don't furtherly
  				 * mess with the value.
  				 */
  				return 0;
  			}

  			*level = acpi_video_bqc_value_to_level(device, *level);

  			for (i = 2; i < device->brightness->count; i++)
  				if (device->brightness->levels[i] == *level) {
  					device->brightness->curr = *level;
  					return 0;

  				}

  			/*
  			 * BQC returned an invalid level.
  			 * Stop using it.
  			 */
  			ACPI_WARNING((AE_INFO,
  				      "%s returned an invalid level",
  				      buf));
  			device->cap._BQC = device->cap._BCQ = 0;

  		} else {

  			/*
  			 * Fixme:

  			 * should we return an error or ignore this failure?
  			 * dev->brightness->curr is a cached value which stores
  			 * the correct current backlight level in most cases.
  			 * ACPI video backlight still works w/ buggy _BQC.
  			 * http://bugzilla.kernel.org/show_bug.cgi?id=12233
  			 */

  			ACPI_WARNING((AE_INFO, "Evaluating %s failed", buf));
  			device->cap._BQC = device->cap._BCQ = 0;

  		}
  	}

  	*level = device->brightness->curr;

  	return 0;

  }
  
  static int

  acpi_video_device_EDID(struct acpi_video_device *device,
  		       union acpi_object **edid, ssize_t length)

  {

  	int status;
  	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
  	union acpi_object *obj;
  	union acpi_object arg0 = { ACPI_TYPE_INTEGER };
  	struct acpi_object_list args = { 1, &arg0 };

  
  	*edid = NULL;
  
  	if (!device)

  		return -ENODEV;

  	if (length == 128)
  		arg0.integer.value = 1;
  	else if (length == 256)
  		arg0.integer.value = 2;
  	else

  		return -EINVAL;

  	status = acpi_evaluate_object(device->dev->handle, "_DDC", &args, &buffer);

  	if (ACPI_FAILURE(status))

  		return -ENODEV;

  	obj = buffer.pointer;

  
  	if (obj && obj->type == ACPI_TYPE_BUFFER)
  		*edid = obj;
  	else {

  		printk(KERN_ERR PREFIX "Invalid _DDC data
  ");

  		status = -EFAULT;
  		kfree(obj);
  	}

  	return status;

  }

  /* bus */

  /*
   *  Arg:

   *	video		: video bus device pointer
   *	bios_flag	:

   *		0.	The system BIOS should NOT automatically switch(toggle)
   *			the active display output.
   *		1.	The system BIOS should automatically switch (toggle) the

   *			active display output. No switch event.

   *		2.	The _DGS value should be locked.
   *		3.	The system BIOS should not automatically switch (toggle) the
   *			active display output, but instead generate the display switch
   *			event notify code.
   *	lcd_flag	:
   *		0.	The system BIOS should automatically control the brightness level

   *			of the LCD when the power changes from AC to DC

   *		1.	The system BIOS should NOT automatically control the brightness

   *			level of the LCD when the power changes from AC to DC.

   *  Return Value:

   *		-EINVAL	wrong arg.

   */
  
  static int

  acpi_video_bus_DOS(struct acpi_video_bus *video, int bios_flag, int lcd_flag)

  {

  	acpi_status status;

  	if (!video->cap._DOS)
  		return 0;

  	if (bios_flag < 0 || bios_flag > 3 || lcd_flag < 0 || lcd_flag > 1)
  		return -EINVAL;

  	video->dos_setting = (lcd_flag << 2) | bios_flag;
  	status = acpi_execute_simple_method(video->device->handle, "_DOS",
  					    (lcd_flag << 2) | bios_flag);

  	if (ACPI_FAILURE(status))
  		return -EIO;

  	return 0;

  }
  
  /*

   * Simple comparison function used to sort backlight levels.
   */
  
  static int
  acpi_video_cmp_level(const void *a, const void *b)
  {
  	return *(int *)a - *(int *)b;
  }
  
  /*

   * Decides if _BQC/_BCQ for this system is usable
   *
   * We do this by changing the level first and then read out the current
   * brightness level, if the value does not match, find out if it is using
   * index. If not, clear the _BQC/_BCQ capability.
   */
  static int acpi_video_bqc_quirk(struct acpi_video_device *device,
  				int max_level, int current_level)
  {
  	struct acpi_video_device_brightness *br = device->brightness;
  	int result;
  	unsigned long long level;
  	int test_level;
  
  	/* don't mess with existing known broken systems */
  	if (bqc_offset_aml_bug_workaround)
  		return 0;
  
  	/*
  	 * Some systems always report current brightness level as maximum
  	 * through _BQC, we need to test another value for them.
  	 */

  	test_level = current_level == max_level ? br->levels[3] : max_level;

  
  	result = acpi_video_device_lcd_set_level(device, test_level);
  	if (result)
  		return result;
  
  	result = acpi_video_device_lcd_get_level_current(device, &level, true);
  	if (result)
  		return result;
  
  	if (level != test_level) {
  		/* buggy _BQC found, need to find out if it uses index */
  		if (level < br->count) {
  			if (br->flags._BCL_reversed)
  				level = br->count - 3 - level;
  			if (br->levels[level + 2] == test_level)
  				br->flags._BQC_use_index = 1;
  		}
  
  		if (!br->flags._BQC_use_index)
  			device->cap._BQC = device->cap._BCQ = 0;
  	}
  
  	return 0;
  }
  
  
  /*

   *  Arg:
   *	device	: video output device (LCD, CRT, ..)

   *
   *  Return Value:

   *	Maximum brightness level
   *
   *  Allocate and initialize device->brightness.
   */
  
  static int
  acpi_video_init_brightness(struct acpi_video_device *device)
  {
  	union acpi_object *obj = NULL;

  	int i, max_level = 0, count = 0, level_ac_battery = 0;

  	unsigned long long level, level_old;

  	union acpi_object *o;
  	struct acpi_video_device_brightness *br = NULL;

  	int result = -EINVAL;

  	u32 value;

  
  	if (!ACPI_SUCCESS(acpi_video_device_lcd_query_levels(device, &obj))) {
  		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Could not query available "
  						"LCD brightness level
  "));
  		goto out;
  	}
  
  	if (obj->package.count < 2)
  		goto out;
  
  	br = kzalloc(sizeof(*br), GFP_KERNEL);
  	if (!br) {
  		printk(KERN_ERR "can't allocate memory
  ");

  		result = -ENOMEM;

  		goto out;
  	}

  	br->levels = kmalloc((obj->package.count + 2) * sizeof *(br->levels),

  				GFP_KERNEL);

  	if (!br->levels) {
  		result = -ENOMEM;

  		goto out_free;

  	}

  
  	for (i = 0; i < obj->package.count; i++) {
  		o = (union acpi_object *)&obj->package.elements[i];
  		if (o->type != ACPI_TYPE_INTEGER) {
  			printk(KERN_ERR PREFIX "Invalid data
  ");
  			continue;
  		}

  		value = (u32) o->integer.value;
  		/* Skip duplicate entries */
  		if (count > 2 && br->levels[count - 1] == value)
  			continue;
  
  		br->levels[count] = value;

  
  		if (br->levels[count] > max_level)
  			max_level = br->levels[count];
  		count++;
  	}

  	/*
  	 * some buggy BIOS don't export the levels
  	 * when machine is on AC/Battery in _BCL package.
  	 * In this case, the first two elements in _BCL packages
  	 * are also supported brightness levels that OS should take care of.
  	 */

  	for (i = 2; i < count; i++) {
  		if (br->levels[i] == br->levels[0])

  			level_ac_battery++;

  		if (br->levels[i] == br->levels[1])
  			level_ac_battery++;
  	}

  
  	if (level_ac_battery < 2) {
  		level_ac_battery = 2 - level_ac_battery;
  		br->flags._BCL_no_ac_battery_levels = 1;
  		for (i = (count - 1 + level_ac_battery); i >= 2; i--)
  			br->levels[i] = br->levels[i - level_ac_battery];
  		count += level_ac_battery;
  	} else if (level_ac_battery > 2)

  		ACPI_ERROR((AE_INFO, "Too many duplicates in _BCL package"));

  	/* Check if the _BCL package is in a reversed order */
  	if (max_level == br->levels[2]) {
  		br->flags._BCL_reversed = 1;
  		sort(&br->levels[2], count - 2, sizeof(br->levels[2]),
  			acpi_video_cmp_level, NULL);
  	} else if (max_level != br->levels[count - 1])
  		ACPI_ERROR((AE_INFO,

  			    "Found unordered _BCL package"));

  
  	br->count = count;
  	device->brightness = br;

  	/* _BQC uses INDEX while _BCL uses VALUE in some laptops */

  	br->curr = level = max_level;

  
  	if (!device->cap._BQC)
  		goto set_level;

  	result = acpi_video_device_lcd_get_level_current(device,
  							 &level_old, true);

  	if (result)
  		goto out_free_levels;

  	result = acpi_video_bqc_quirk(device, max_level, level_old);

  	if (result)
  		goto out_free_levels;

  	/*
  	 * cap._BQC may get cleared due to _BQC is found to be broken
  	 * in acpi_video_bqc_quirk, so check again here.
  	 */
  	if (!device->cap._BQC)
  		goto set_level;

  	level = acpi_video_bqc_value_to_level(device, level_old);
  	/*
  	 * On some buggy laptops, _BQC returns an uninitialized
  	 * value when invoked for the first time, i.e.
  	 * level_old is invalid (no matter whether it's a level
  	 * or an index). Set the backlight to max_level in this case.
  	 */
  	for (i = 2; i < br->count; i++)
  		if (level == br->levels[i])
  			break;
  	if (i == br->count || !level)
  		level = max_level;

  set_level:

  	result = acpi_video_device_lcd_set_level(device, level);

  	if (result)
  		goto out_free_levels;

  	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
  			  "found %d brightness levels
  ", count - 2));

  	kfree(obj);

  	return result;

  
  out_free_levels:
  	kfree(br->levels);
  out_free:
  	kfree(br);
  out:
  	device->brightness = NULL;
  	kfree(obj);

  	return result;

  }
  
  /*
   *  Arg:
   *	device	: video output device (LCD, CRT, ..)
   *
   *  Return Value:

   *	None

   *

   *  Find out all required AML methods defined under the output

   *  device.
   */

  static void acpi_video_device_find_cap(struct acpi_video_device *device)

  {

  	if (acpi_has_method(device->dev->handle, "_ADR"))

  		device->cap._ADR = 1;

  	if (acpi_has_method(device->dev->handle, "_BCL"))

  		device->cap._BCL = 1;

  	if (acpi_has_method(device->dev->handle, "_BCM"))

  		device->cap._BCM = 1;

  	if (acpi_has_method(device->dev->handle, "_BQC")) {

  		device->cap._BQC = 1;

  	} else if (acpi_has_method(device->dev->handle, "_BCQ")) {

  		printk(KERN_WARNING FW_BUG "_BCQ is used instead of _BQC
  ");
  		device->cap._BCQ = 1;
  	}

  	if (acpi_has_method(device->dev->handle, "_DDC"))

  		device->cap._DDC = 1;

  }
  
  /*

   *  Arg:
   *	device	: video output device (VGA)

   *
   *  Return Value:

   *	None

   *

   *  Find out all required AML methods defined under the video bus device.

   */

  static void acpi_video_bus_find_cap(struct acpi_video_bus *video)

  {

  	if (acpi_has_method(video->device->handle, "_DOS"))

  		video->cap._DOS = 1;

  	if (acpi_has_method(video->device->handle, "_DOD"))

  		video->cap._DOD = 1;

  	if (acpi_has_method(video->device->handle, "_ROM"))

  		video->cap._ROM = 1;

  	if (acpi_has_method(video->device->handle, "_GPD"))

  		video->cap._GPD = 1;

  	if (acpi_has_method(video->device->handle, "_SPD"))

  		video->cap._SPD = 1;

  	if (acpi_has_method(video->device->handle, "_VPO"))

  		video->cap._VPO = 1;

  }
  
  /*
   * Check whether the video bus device has required AML method to
   * support the desired features
   */

  static int acpi_video_bus_check(struct acpi_video_bus *video)

  {

  	acpi_status status = -ENOENT;

  	struct pci_dev *dev;

  
  	if (!video)

  		return -EINVAL;

  	dev = acpi_get_pci_dev(video->device->handle);

  	if (!dev)
  		return -ENODEV;

  	pci_dev_put(dev);

  	/*
  	 * Since there is no HID, CID and so on for VGA driver, we have

  	 * to check well known required nodes.
  	 */

  	/* Does this device support video switching? */

  	if (video->cap._DOS || video->cap._DOD) {
  		if (!video->cap._DOS) {
  			printk(KERN_WARNING FW_BUG
  				"ACPI(%s) defines _DOD but not _DOS
  ",
  				acpi_device_bid(video->device));
  		}

  		video->flags.multihead = 1;
  		status = 0;
  	}

  	/* Does this device support retrieving a video ROM? */

  	if (video->cap._ROM) {

  		video->flags.rom = 1;
  		status = 0;
  	}

  	/* Does this device support configuring which video device to POST? */

  	if (video->cap._GPD && video->cap._SPD && video->cap._VPO) {

  		video->flags.post = 1;
  		status = 0;
  	}

  	return status;

  }

  /*
   * --------------------------------------------------------------------------
   *                               Driver Interface
   * --------------------------------------------------------------------------
   */

  
  /* device interface */

  static struct acpi_video_device_attrib *

  acpi_video_get_device_attr(struct acpi_video_bus *video, unsigned long device_id)
  {

  	struct acpi_video_enumerated_device *ids;
  	int i;
  
  	for (i = 0; i < video->attached_count; i++) {
  		ids = &video->attached_array[i];
  		if ((ids->value.int_val & 0xffff) == device_id)
  			return &ids->value.attrib;
  	}

  	return NULL;
  }

  
  static int

  acpi_video_get_device_type(struct acpi_video_bus *video,
  			   unsigned long device_id)
  {
  	struct acpi_video_enumerated_device *ids;
  	int i;
  
  	for (i = 0; i < video->attached_count; i++) {
  		ids = &video->attached_array[i];
  		if ((ids->value.int_val & 0xffff) == device_id)
  			return ids->value.int_val;
  	}
  
  	return 0;
  }
  
  static int

  acpi_video_bus_get_one_device(struct acpi_device *device,
  			      struct acpi_video_bus *video)

  {

  	unsigned long long device_id;

  	int status, device_type;

  	struct acpi_video_device *data;

  	struct acpi_video_device_attrib *attribute;

  	status =
  	    acpi_evaluate_integer(device->handle, "_ADR", NULL, &device_id);

  	/* Some device omits _ADR, we skip them instead of fail */
  	if (ACPI_FAILURE(status))
  		return 0;

  	data = kzalloc(sizeof(struct acpi_video_device), GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;

  	strcpy(acpi_device_name(device), ACPI_VIDEO_DEVICE_NAME);
  	strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);
  	device->driver_data = data;
  
  	data->device_id = device_id;
  	data->video = video;
  	data->dev = device;

  	INIT_DELAYED_WORK(&data->switch_brightness_work,
  			  acpi_video_switch_brightness);

  
  	attribute = acpi_video_get_device_attr(video, device_id);

  	if (attribute && attribute->device_id_scheme) {

  		switch (attribute->display_type) {
  		case ACPI_VIDEO_DISPLAY_CRT:
  			data->flags.crt = 1;
  			break;
  		case ACPI_VIDEO_DISPLAY_TV:
  			data->flags.tvout = 1;
  			break;
  		case ACPI_VIDEO_DISPLAY_DVI:
  			data->flags.dvi = 1;
  			break;
  		case ACPI_VIDEO_DISPLAY_LCD:
  			data->flags.lcd = 1;
  			break;
  		default:
  			data->flags.unknown = 1;
  			break;
  		}

  		if (attribute->bios_can_detect)

  			data->flags.bios = 1;
  	} else {
  		/* Check for legacy IDs */
  		device_type = acpi_video_get_device_type(video, device_id);
  		/* Ignore bits 16 and 18-20 */
  		switch (device_type & 0xffe2ffff) {

  		case ACPI_VIDEO_DISPLAY_LEGACY_MONITOR:
  			data->flags.crt = 1;
  			break;
  		case ACPI_VIDEO_DISPLAY_LEGACY_PANEL:
  			data->flags.lcd = 1;
  			break;
  		case ACPI_VIDEO_DISPLAY_LEGACY_TV:
  			data->flags.tvout = 1;
  			break;
  		default:
  			data->flags.unknown = 1;

  		}

  	}

  	acpi_video_device_bind(video, data);
  	acpi_video_device_find_cap(data);

  	mutex_lock(&video->device_list_lock);
  	list_add_tail(&data->entry, &video->video_device_list);
  	mutex_unlock(&video->device_list_lock);

  	return status;

  }
  
  /*
   *  Arg:

   *	video	: video bus device

   *
   *  Return:

   *	none
   *
   *  Enumerate the video device list of the video bus,

   *  bind the ids with the corresponding video devices
   *  under the video bus.

   */

  static void acpi_video_device_rebind(struct acpi_video_bus *video)

  {

  	struct acpi_video_device *dev;

  	mutex_lock(&video->device_list_lock);

  
  	list_for_each_entry(dev, &video->video_device_list, entry)

  		acpi_video_device_bind(video, dev);

  	mutex_unlock(&video->device_list_lock);

  }
  
  /*
   *  Arg:

   *	video	: video bus device
   *	device	: video output device under the video
   *		bus

   *
   *  Return:

   *	none
   *

   *  Bind the ids with the corresponding video devices
   *  under the video bus.

   */

  
  static void

  acpi_video_device_bind(struct acpi_video_bus *video,
  		       struct acpi_video_device *device)

  {

  	struct acpi_video_enumerated_device *ids;

  	int i;

  	for (i = 0; i < video->attached_count; i++) {
  		ids = &video->attached_array[i];
  		if (device->device_id == (ids->value.int_val & 0xffff)) {
  			ids->bind_info = device;

  			ACPI_DEBUG_PRINT((ACPI_DB_INFO, "device_bind %d
  ", i));
  		}
  	}

  }

  static bool acpi_video_device_in_dod(struct acpi_video_device *device)
  {
  	struct acpi_video_bus *video = device->video;
  	int i;

  	/*
  	 * If we have a broken _DOD or we have more than 8 output devices
  	 * under the graphics controller node that we can't proper deal with
  	 * in the operation region code currently, no need to test.
  	 */
  	if (!video->attached_count || video->child_count > 8)

  		return true;
  
  	for (i = 0; i < video->attached_count; i++) {

  		if ((video->attached_array[i].value.int_val & 0xfff) ==
  		    (device->device_id & 0xfff))

  			return true;
  	}
  
  	return false;
  }

  /*
   *  Arg:

   *	video	: video bus device

   *
   *  Return:

   *	< 0	: error
   *

   *  Call _DOD to enumerate all devices attached to display adapter
   *

   */

  
  static int acpi_video_device_enumerate(struct acpi_video_bus *video)
  {

  	int status;
  	int count;
  	int i;

  	struct acpi_video_enumerated_device *active_list;

  	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
  	union acpi_object *dod = NULL;
  	union acpi_object *obj;

  	status = acpi_evaluate_object(video->device->handle, "_DOD", NULL, &buffer);

  	if (!ACPI_SUCCESS(status)) {

  		ACPI_EXCEPTION((AE_INFO, status, "Evaluating _DOD"));

  		return status;

  	}

  	dod = buffer.pointer;

  	if (!dod || (dod->type != ACPI_TYPE_PACKAGE)) {

  		ACPI_EXCEPTION((AE_INFO, status, "Invalid _DOD data"));

  		status = -EFAULT;
  		goto out;
  	}
  
  	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d video heads in _DOD
  ",

  			  dod->package.count));

  	active_list = kcalloc(1 + dod->package.count,
  			      sizeof(struct acpi_video_enumerated_device),
  			      GFP_KERNEL);
  	if (!active_list) {

  		status = -ENOMEM;
  		goto out;
  	}
  
  	count = 0;
  	for (i = 0; i < dod->package.count; i++) {

  		obj = &dod->package.elements[i];

  
  		if (obj->type != ACPI_TYPE_INTEGER) {

  			printk(KERN_ERR PREFIX
  				"Invalid _DOD data in element %d
  ", i);
  			continue;

  		}

  
  		active_list[count].value.int_val = obj->integer.value;
  		active_list[count].bind_info = NULL;

  		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "dod element[%d] = %d
  ", i,
  				  (int)obj->integer.value));

  		count++;
  	}

  	kfree(video->attached_array);

  	video->attached_array = active_list;

  	video->attached_count = count;

  out:

  	kfree(buffer.pointer);

  	return status;

  }

  static int
  acpi_video_get_next_level(struct acpi_video_device *device,
  			  u32 level_current, u32 event)

  {

  	int min, max, min_above, max_below, i, l, delta = 255;

  	max = max_below = 0;
  	min = min_above = 255;

  	/* Find closest level to level_current */

  	for (i = 2; i < device->brightness->count; i++) {

  		l = device->brightness->levels[i];
  		if (abs(l - level_current) < abs(delta)) {
  			delta = l - level_current;
  			if (!delta)
  				break;
  		}
  	}
  	/* Ajust level_current to closest available level */
  	level_current += delta;

  	for (i = 2; i < device->brightness->count; i++) {

  		l = device->brightness->levels[i];
  		if (l < min)
  			min = l;
  		if (l > max)
  			max = l;
  		if (l < min_above && l > level_current)
  			min_above = l;
  		if (l > max_below && l < level_current)
  			max_below = l;
  	}
  
  	switch (event) {
  	case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:
  		return (level_current < max) ? min_above : min;
  	case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:
  		return (level_current < max) ? min_above : max;
  	case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:
  		return (level_current > min) ? max_below : min;
  	case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS:
  	case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:
  		return 0;
  	default:
  		return level_current;
  	}

  }

  static void
  acpi_video_switch_brightness(struct work_struct *work)

  {

  	struct acpi_video_device *device = container_of(to_delayed_work(work),
  			     struct acpi_video_device, switch_brightness_work);

  	unsigned long long level_current, level_next;

  	int event = device->switch_brightness_event;

  	int result = -EINVAL;

  	/* no warning message if acpi_backlight=vendor or a quirk is used */
  	if (!acpi_video_verify_backlight_support())

  		return;

  	if (!device->brightness)

  		goto out;
  
  	result = acpi_video_device_lcd_get_level_current(device,

  							 &level_current,
  							 false);

  	if (result)
  		goto out;

  	level_next = acpi_video_get_next_level(device, level_current, event);

  	result = acpi_video_device_lcd_set_level(device, level_next);

  	if (!result)
  		backlight_force_update(device->backlight,
  				       BACKLIGHT_UPDATE_HOTKEY);

  out:
  	if (result)
  		printk(KERN_ERR PREFIX "Failed to switch the brightness
  ");

  }

  int acpi_video_get_edid(struct acpi_device *device, int type, int device_id,
  			void **edid)
  {
  	struct acpi_video_bus *video;
  	struct acpi_video_device *video_device;
  	union acpi_object *buffer = NULL;
  	acpi_status status;
  	int i, length;
  
  	if (!device || !acpi_driver_data(device))
  		return -EINVAL;
  
  	video = acpi_driver_data(device);
  
  	for (i = 0; i < video->attached_count; i++) {
  		video_device = video->attached_array[i].bind_info;
  		length = 256;
  
  		if (!video_device)
  			continue;

  		if (!video_device->cap._DDC)
  			continue;

  		if (type) {
  			switch (type) {
  			case ACPI_VIDEO_DISPLAY_CRT:
  				if (!video_device->flags.crt)
  					continue;
  				break;
  			case ACPI_VIDEO_DISPLAY_TV:
  				if (!video_device->flags.tvout)
  					continue;
  				break;
  			case ACPI_VIDEO_DISPLAY_DVI:
  				if (!video_device->flags.dvi)
  					continue;
  				break;
  			case ACPI_VIDEO_DISPLAY_LCD:
  				if (!video_device->flags.lcd)
  					continue;
  				break;
  			}
  		} else if (video_device->device_id != device_id) {
  			continue;
  		}
  
  		status = acpi_video_device_EDID(video_device, &buffer, length);
  
  		if (ACPI_FAILURE(status) || !buffer ||
  		    buffer->type != ACPI_TYPE_BUFFER) {
  			length = 128;
  			status = acpi_video_device_EDID(video_device, &buffer,
  							length);
  			if (ACPI_FAILURE(status) || !buffer ||
  			    buffer->type != ACPI_TYPE_BUFFER) {
  				continue;
  			}
  		}
  
  		*edid = buffer->buffer.pointer;
  		return length;
  	}
  
  	return -ENODEV;
  }
  EXPORT_SYMBOL(acpi_video_get_edid);

  static int

  acpi_video_bus_get_devices(struct acpi_video_bus *video,
  			   struct acpi_device *device)

  {

  	int status = 0;

  	struct acpi_device *dev;

  	/*
  	 * There are systems where video module known to work fine regardless
  	 * of broken _DOD and ignoring returned value here doesn't cause
  	 * any issues later.
  	 */
  	acpi_video_device_enumerate(video);

  	list_for_each_entry(dev, &device->children, node) {

  
  		status = acpi_video_bus_get_one_device(dev, video);

  		if (status) {

  			dev_err(&dev->dev, "Can't attach device
  ");
  			break;

  		}

  		video->child_count++;

  	}

  	return status;

  }

  /* acpi_video interface */

  /*
   * Win8 requires setting bit2 of _DOS to let firmware know it shouldn't
   * preform any automatic brightness change on receiving a notification.
   */

  static int acpi_video_bus_start_devices(struct acpi_video_bus *video)

  {

  	return acpi_video_bus_DOS(video, 0,

  				  acpi_osi_is_win8() ? 1 : 0);

  }

  static int acpi_video_bus_stop_devices(struct acpi_video_bus *video)

  {

  	return acpi_video_bus_DOS(video, 0,

  				  acpi_osi_is_win8() ? 0 : 1);

  }

  static void acpi_video_bus_notify(struct acpi_device *device, u32 event)

  {

  	struct acpi_video_bus *video = acpi_driver_data(device);

  	struct input_dev *input;

  	int keycode = 0;

  	if (!video || !video->input)

  		return;

  	input = video->input;

  
  	switch (event) {

  	case ACPI_VIDEO_NOTIFY_SWITCH:	/* User requested a switch,

  					 * most likely via hotkey. */

  		keycode = KEY_SWITCHVIDEOMODE;

  		break;

  	case ACPI_VIDEO_NOTIFY_PROBE:	/* User plugged in or removed a video

  					 * connector. */
  		acpi_video_device_enumerate(video);
  		acpi_video_device_rebind(video);

  		keycode = KEY_SWITCHVIDEOMODE;

  		break;

  	case ACPI_VIDEO_NOTIFY_CYCLE:	/* Cycle Display output hotkey pressed. */

  		keycode = KEY_SWITCHVIDEOMODE;
  		break;

  	case ACPI_VIDEO_NOTIFY_NEXT_OUTPUT:	/* Next Display output hotkey pressed. */

  		keycode = KEY_VIDEO_NEXT;
  		break;

  	case ACPI_VIDEO_NOTIFY_PREV_OUTPUT:	/* previous Display output hotkey pressed. */

  		keycode = KEY_VIDEO_PREV;

  		break;
  
  	default:
  		ACPI_DEBUG_PRINT((ACPI_DB_INFO,

  				  "Unsupported event [0x%x]
  ", event));

  		break;
  	}

  	if (acpi_notifier_call_chain(device, event, 0))
  		/* Something vetoed the keypress. */
  		keycode = 0;

  
  	if (keycode) {
  		input_report_key(input, keycode, 1);
  		input_sync(input);
  		input_report_key(input, keycode, 0);
  		input_sync(input);
  	}

  	return;

  }

  static void brightness_switch_event(struct acpi_video_device *video_device,
  				    u32 event)
  {
  	if (!brightness_switch_enabled)
  		return;
  
  	video_device->switch_brightness_event = event;
  	schedule_delayed_work(&video_device->switch_brightness_work, HZ / 10);
  }

  static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data)

  {

  	struct acpi_video_device *video_device = data;

  	struct acpi_device *device = NULL;

  	struct acpi_video_bus *bus;
  	struct input_dev *input;

  	int keycode = 0;

  	if (!video_device)

  		return;

  	device = video_device->dev;

  	bus = video_device->video;
  	input = bus->input;

  
  	switch (event) {

  	case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:	/* Cycle brightness */

  		brightness_switch_event(video_device, event);

  		keycode = KEY_BRIGHTNESS_CYCLE;
  		break;

  	case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:	/* Increase brightness */

  		brightness_switch_event(video_device, event);

  		keycode = KEY_BRIGHTNESSUP;
  		break;

  	case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:	/* Decrease brightness */

  		brightness_switch_event(video_device, event);

  		keycode = KEY_BRIGHTNESSDOWN;
  		break;

  	case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS:	/* zero brightness */

  		brightness_switch_event(video_device, event);

  		keycode = KEY_BRIGHTNESS_ZERO;
  		break;

  	case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:	/* display device off */

  		brightness_switch_event(video_device, event);

  		keycode = KEY_DISPLAY_OFF;

  		break;
  	default:
  		ACPI_DEBUG_PRINT((ACPI_DB_INFO,

  				  "Unsupported event [0x%x]
  ", event));

  		break;
  	}

  	acpi_notifier_call_chain(device, event, 0);

  
  	if (keycode) {
  		input_report_key(input, keycode, 1);
  		input_sync(input);
  		input_report_key(input, keycode, 0);
  		input_sync(input);
  	}

  	return;

  }

  static int acpi_video_resume(struct notifier_block *nb,
  				unsigned long val, void *ign)

  {
  	struct acpi_video_bus *video;
  	struct acpi_video_device *video_device;
  	int i;

  	switch (val) {
  	case PM_HIBERNATION_PREPARE:
  	case PM_SUSPEND_PREPARE:
  	case PM_RESTORE_PREPARE:
  		return NOTIFY_DONE;
  	}

  	video = container_of(nb, struct acpi_video_bus, pm_nb);
  
  	dev_info(&video->device->dev, "Restoring backlight state
  ");