text: /*
   *  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.
   *
   * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   */
  
  #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>
  
  #define PREFIX "ACPI: "
  
  #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);
  
  static int disable_backlight_sysfs_if = -1;
  module_param(disable_backlight_sysfs_if, int, 0444);
  
  #define REPORT_OUTPUT_KEY_EVENTS		0x01
  #define REPORT_BRIGHTNESS_KEY_EVENTS		0x02
  static int report_key_events = -1;
  module_param(report_key_events, int, 0644);
  MODULE_PARM_DESC(report_key_events,
  	"0: none, 1: output changes, 2: brightness changes, 3: all");
  
  static bool device_id_scheme = false;
  module_param(device_id_scheme, bool, 0444);
  
  static int only_lcd = -1;
  module_param(only_lcd, int, 0444);
  
  static int register_count;
  static DEFINE_MUTEX(register_count_mutex);
  static DEFINE_MUTEX(video_list_lock);
  static 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);
  void acpi_video_detect_exit(void);
  
  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;
  	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 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_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 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);
  
  /* 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(acpi_handle handle,
  				   union acpi_object **levels)
  {
  	int status;
  	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
  	union acpi_object *obj;
  
  
  	*levels = NULL;
  
  	status = acpi_evaluate_object(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\n");
  		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 video_set_bqc_offset(const struct dmi_system_id *d)
  {
  	bqc_offset_aml_bug_workaround = 9;
  	return 0;
  }
  
  static int video_disable_backlight_sysfs_if(
  	const struct dmi_system_id *d)
  {
  	if (disable_backlight_sysfs_if == -1)
  		disable_backlight_sysfs_if = 1;
  	return 0;
  }
  
  static int video_set_device_id_scheme(const struct dmi_system_id *d)
  {
  	device_id_scheme = true;
  	return 0;
  }
  
  static int video_enable_only_lcd(const struct dmi_system_id *d)
  {
  	only_lcd = true;
  	return 0;
  }
  
  static int video_set_report_key_events(const struct dmi_system_id *id)
  {
  	if (report_key_events == -1)
  		report_key_events = (uintptr_t)id->driver_data;
  	return 0;
  }
  
  static struct dmi_system_id video_dmi_table[] = {
  	/*
  	 * 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"),
  		},
  	},
  
  	/*
  	 * Some machines have a broken acpi-video interface for brightness
  	 * control, but still need an acpi_video_device_lcd_set_level() call
  	 * on resume to turn the backlight power on.  We Enable backlight
  	 * control on these systems, but do not register a backlight sysfs
  	 * as brightness control does not work.
  	 */
  	{
  	 /* https://bugzilla.kernel.org/show_bug.cgi?id=21012 */
  	 .callback = video_disable_backlight_sysfs_if,
  	 .ident = "Toshiba Portege R700",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
  		DMI_MATCH(DMI_PRODUCT_NAME, "PORTEGE R700"),
  		},
  	},
  	{
  	 /* https://bugs.freedesktop.org/show_bug.cgi?id=82634 */
  	 .callback = video_disable_backlight_sysfs_if,
  	 .ident = "Toshiba Portege R830",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
  		DMI_MATCH(DMI_PRODUCT_NAME, "PORTEGE R830"),
  		},
  	},
  	{
  	 /* https://bugzilla.kernel.org/show_bug.cgi?id=21012 */
  	 .callback = video_disable_backlight_sysfs_if,
  	 .ident = "Toshiba Satellite R830",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
  		DMI_MATCH(DMI_PRODUCT_NAME, "SATELLITE R830"),
  		},
  	},
  	/*
  	 * Some machine's _DOD IDs don't have bit 31(Device ID Scheme) set
  	 * but the IDs actually follow the Device ID Scheme.
  	 */
  	{
  	 /* https://bugzilla.kernel.org/show_bug.cgi?id=104121 */
  	 .callback = video_set_device_id_scheme,
  	 .ident = "ESPRIMO Mobile M9410",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU SIEMENS"),
  		DMI_MATCH(DMI_PRODUCT_NAME, "ESPRIMO Mobile M9410"),
  		},
  	},
  	/*
  	 * Some machines have multiple video output devices, but only the one
  	 * that is the type of LCD can do the backlight control so we should not
  	 * register backlight interface for other video output devices.
  	 */
  	{
  	 /* https://bugzilla.kernel.org/show_bug.cgi?id=104121 */
  	 .callback = video_enable_only_lcd,
  	 .ident = "ESPRIMO Mobile M9410",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU SIEMENS"),
  		DMI_MATCH(DMI_PRODUCT_NAME, "ESPRIMO Mobile M9410"),
  		},
  	},
  	/*
  	 * Some machines report wrong key events on the acpi-bus, suppress
  	 * key event reporting on these.  Note this is only intended to work
  	 * around events which are plain wrong. In some cases we get double
  	 * events, in this case acpi-video is considered the canonical source
  	 * and the events from the other source should be filtered. E.g.
  	 * by calling acpi_video_handles_brightness_key_presses() from the
  	 * vendor acpi/wmi driver or by using /lib/udev/hwdb.d/60-keyboard.hwdb
  	 */
  	{
  	 .callback = video_set_report_key_events,
  	 .driver_data = (void *)((uintptr_t)REPORT_OUTPUT_KEY_EVENTS),
  	 .ident = "Dell Vostro V131",
  	 .matches = {
  		DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
  		DMI_MATCH(DMI_PRODUCT_NAME, "Vostro V131"),
  		},
  	},
  	{}
  };
  
  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\n");
  		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;
  }
  
  int acpi_video_get_levels(struct acpi_device *device,
  			  struct acpi_video_device_brightness **dev_br,
  			  int *pmax_level)
  {
  	union acpi_object *obj = NULL;
  	int i, max_level = 0, count = 0, level_ac_battery = 0;
  	union acpi_object *o;
  	struct acpi_video_device_brightness *br = NULL;
  	int result = 0;
  	u32 value;
  
  	if (!ACPI_SUCCESS(acpi_video_device_lcd_query_levels(device->handle,
  								&obj))) {
  		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Could not query available "
  						"LCD brightness level\n"));
  		result = -ENODEV;
  		goto out;
  	}
  
  	if (obj->package.count < 2) {
  		result = -EINVAL;
  		goto out;
  	}
  
  	br = kzalloc(sizeof(*br), GFP_KERNEL);
  	if (!br) {
  		printk(KERN_ERR "can't allocate memory\n");
  		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\n");
  			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;
  	*dev_br = br;
  	if (pmax_level)
  		*pmax_level = max_level;
  
  out:
  	kfree(obj);
  	return result;
  out_free:
  	kfree(br);
  	goto out;
  }
  EXPORT_SYMBOL(acpi_video_get_levels);
  
  /*
   *  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)
  {
  	int i, max_level = 0;
  	unsigned long long level, level_old;
  	struct acpi_video_device_brightness *br = NULL;
  	int result = -EINVAL;
  
  	result = acpi_video_get_levels(device->dev, &br, &max_level);
  	if (result)
  		return result;
  	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\n", br->count - 2));
  	return 0;
  
  out_free_levels:
  	kfree(br->levels);
  	kfree(br);
  	device->brightness = NULL;
  	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\n");
  		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\n",
  				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 || 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\n", 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;
  
  	if (!video->cap._DOD)
  		return AE_NOT_EXIST;
  
  	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\n",
  			  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\n", 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\n", 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 (!device->backlight)
  		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\n");
  }
  
  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\n");
  			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]\n", event));
  		break;
  	}
  
  	if (acpi_notifier_call_chain(device, event, 0))
  		/* Something vetoed the keypress. */
  		keycode = 0;
  
  	if (keycode && (report_key_events & REPORT_OUTPUT_KEY_EVENTS)) {
  		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]\n", event));
  		break;
  	}
  
  	acpi_notifier_call_chain(device, event, 0);
  
  	if (keycode && (report_key_events & REPORT_BRIGHTNESS_KEY_EVENTS)) {
  		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\n");
  
  	for (i = 0; i < video->attached_count; i++) {
  		video_device = video->attached_array[i].bind_info;
  		if (video_device && video_device->brightness)
  			acpi_video_device_lcd_set_level(video_device,
  					video_device->brightness->curr);
  	}
  
  	return NOTIFY_OK;
  }
  
  static acpi_status
  acpi_video_bus_match(acpi_handle handle, u32 level, void *context,
  			void **return_value)
  {
  	struct acpi_device *device = context;
  	struct acpi_device *sibling;
  	int result;
  
  	if (handle == device->handle)
  		return AE_CTRL_TERMINATE;
  
  	result = acpi_bus_get_device(handle, &sibling);
  	if (result)
  		return AE_OK;
  
  	if (!strcmp(acpi_device_name(sibling), ACPI_VIDEO_BUS_NAME))
  			return AE_ALREADY_EXISTS;
  
  	return AE_OK;
  }
  
  static void acpi_video_dev_register_backlight(struct acpi_video_device *device)
  {
  	struct backlight_properties props;
  	struct pci_dev *pdev;
  	acpi_handle acpi_parent;
  	struct device *parent = NULL;
  	int result;
  	static int count;
  	char *name;
  
  	result = acpi_video_init_brightness(device);
  	if (result)
  		return;
  
  	if (disable_backlight_sysfs_if > 0)
  		return;
  
  	name = kasprintf(GFP_KERNEL, "acpi_video%d", count);
  	if (!name)
  		return;
  	count++;
  
  	acpi_get_parent(device->dev->handle, &acpi_parent);
  
  	pdev = acpi_get_pci_dev(acpi_parent);
  	if (pdev) {
  		parent = &pdev->dev;
  		pci_dev_put(pdev);
  	}
  
  	memset(&props, 0, sizeof(struct backlight_properties));
  	props.type = BACKLIGHT_FIRMWARE;
  	props.max_brightness = device->brightness->count - 3;
  	device->backlight = backlight_device_register(name,
  						      parent,
  						      device,
  						      &acpi_backlight_ops,
  						      &props);
  	kfree(name);
  	if (IS_ERR(device->backlight)) {
  		device->backlight = NULL;
  		return;
  	}
  
  	/*
  	 * Save current brightness level in case we have to restore it
  	 * before acpi_video_device_lcd_set_level() is called next time.
  	 */
  	device->backlight->props.brightness =
  			acpi_video_get_brightness(device->backlight);
  
  	device->cooling_dev = thermal_cooling_device_register("LCD",
  				device->dev, &video_cooling_ops);
  	if (IS_ERR(device->cooling_dev)) {
  		/*
  		 * Set cooling_dev to NULL so we don't crash trying to free it.
  		 * Also, why the hell we are returning early and not attempt to
  		 * register video output if cooling device registration failed?
  		 * -- dtor
  		 */
  		device->cooling_dev = NULL;
  		return;
  	}
  
  	dev_info(&device->dev->dev, "registered as cooling_device%d\n",
  		 device->cooling_dev->id);
  	result = sysfs_create_link(&device->dev->dev.kobj,
  			&device->cooling_dev->device.kobj,
  			"thermal_cooling");
  	if (result)
  		printk(KERN_ERR PREFIX "Create sysfs link\n");
  	result = sysfs_create_link(&device->cooling_dev->device.kobj,
  			&device->dev->dev.kobj, "device");
  	if (result)
  		printk(KERN_ERR PREFIX "Create sysfs link\n");
  }
  
  static void acpi_video_run_bcl_for_osi(struct acpi_video_bus *video)
  {
  	struct acpi_video_device *dev;
  	union acpi_object *levels;
  
  	mutex_lock(&video->device_list_lock);
  	list_for_each_entry(dev, &video->video_device_list, entry) {
  		if (!acpi_video_device_lcd_query_levels(dev->dev->handle, &levels))
  			kfree(levels);
  	}
  	mutex_unlock(&video->device_list_lock);
  }
  
  static bool acpi_video_should_register_backlight(struct acpi_video_device *dev)
  {
  	/*
  	 * Do not create backlight device for video output
  	 * device that is not in the enumerated list.
  	 */
  	if (!acpi_video_device_in_dod(dev)) {
  		dev_dbg(&dev->dev->dev, "not in _DOD list, ignore\n");
  		return false;
  	}
  
  	if (only_lcd)
  		return dev->flags.lcd;
  	return true;
  }
  
  static int acpi_video_bus_register_backlight(struct acpi_video_bus *video)
  {
  	struct acpi_video_device *dev;
  
  	if (video->backlight_registered)
  		return 0;
  
  	acpi_video_run_bcl_for_osi(video);
  
  	if (acpi_video_get_backlight_type() != acpi_backlight_video)
  		return 0;
  
  	mutex_lock(&video->device_list_lock);
  	list_for_each_entry(dev, &video->video_device_list, entry) {
  		if (acpi_video_should_register_backlight(dev))
  			acpi_video_dev_register_backlight(dev);
  	}
  	mutex_unlock(&video->device_list_lock);
  
  	video->backlight_registered = true;
  
  	video->pm_nb.notifier_call = acpi_video_resume;
  	video->pm_nb.priority = 0;
  	return register_pm_notifier(&video->pm_nb);
  }
  
  static void acpi_video_dev_unregister_backlight(struct acpi_video_device *device)
  {
  	if (device->backlight) {
  		backlight_device_unregister(device->backlight);
  		device->backlight = NULL;
  	}
  	if (device->brightness) {
  		kfree(device->brightness->levels);
  		kfree(device->brightness);
  		device->brightness = NULL;
  	}
  	if (device->cooling_dev) {
  		sysfs_remove_link(&device->dev->dev.kobj, "thermal_cooling");
  		sysfs_remove_link(&device->cooling_dev->device.kobj, "device");
  		thermal_cooling_device_unregister(device->cooling_dev);
  		device->cooling_dev = NULL;
  	}
  }
  
  static int acpi_video_bus_unregister_backlight(struct acpi_video_bus *video)
  {
  	struct acpi_video_device *dev;
  	int error;
  
  	if (!video->backlight_registered)
  		return 0;
  
  	error = unregister_pm_notifier(&video->pm_nb);
  
  	mutex_lock(&video->device_list_lock);
  	list_for_each_entry(dev, &video->video_device_list, entry)
  		acpi_video_dev_unregister_backlight(dev);
  	mutex_unlock(&video->device_list_lock);
  
  	video->backlight_registered = false;
  
  	return error;
  }
  
  static void acpi_video_dev_add_notify_handler(struct acpi_video_device *device)
  {
  	acpi_status status;
  	struct acpi_device *adev = device->dev;
  
  	status = acpi_install_notify_handler(adev->handle, ACPI_DEVICE_NOTIFY,
  					     acpi_video_device_notify, device);
  	if (ACPI_FAILURE(status))
  		dev_err(&adev->dev, "Error installing notify handler\n");
  	else
  		device->flags.notify = 1;
  }
  
  static int acpi_video_bus_add_notify_handler(struct acpi_video_bus *video)
  {
  	struct input_dev *input;
  	struct acpi_video_device *dev;
  	int error;
  
  	video->input = input = input_allocate_device();
  	if (!input) {
  		error = -ENOMEM;
  		goto out;
  	}
  
  	error = acpi_video_bus_start_devices(video);
  	if (error)
  		goto err_free_input;
  
  	snprintf(video->phys, sizeof(video->phys),
  			"%s/video/input0", acpi_device_hid(video->device));
  
  	input->name = acpi_device_name(video->device);
  	input->phys = video->phys;
  	input->id.bustype = BUS_HOST;
  	input->id.product = 0x06;
  	input->dev.parent = &video->device->dev;
  	input->evbit[0] = BIT(EV_KEY);
  	set_bit(KEY_SWITCHVIDEOMODE, input->keybit);
  	set_bit(KEY_VIDEO_NEXT, input->keybit);
  	set_bit(KEY_VIDEO_PREV, input->keybit);
  	set_bit(KEY_BRIGHTNESS_CYCLE, input->keybit);
  	set_bit(KEY_BRIGHTNESSUP, input->keybit);
  	set_bit(KEY_BRIGHTNESSDOWN, input->keybit);
  	set_bit(KEY_BRIGHTNESS_ZERO, input->keybit);
  	set_bit(KEY_DISPLAY_OFF, input->keybit);
  
  	error = input_register_device(input);
  	if (error)
  		goto err_stop_dev;
  
  	mutex_lock(&video->device_list_lock);
  	list_for_each_entry(dev, &video->video_device_list, entry)
  		acpi_video_dev_add_notify_handler(dev);
  	mutex_unlock(&video->device_list_lock);
  
  	return 0;
  
  err_stop_dev:
  	acpi_video_bus_stop_devices(video);
  err_free_input:
  	input_free_device(input);
  	video->input = NULL;
  out:
  	return error;
  }
  
  static void acpi_video_dev_remove_notify_handler(struct acpi_video_device *dev)
  {
  	if (dev->flags.notify) {
  		acpi_remove_notify_handler(dev->dev->handle, ACPI_DEVICE_NOTIFY,
  					   acpi_video_device_notify);
  		dev->flags.notify = 0;
  	}
  }
  
  static void acpi_video_bus_remove_notify_handler(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_dev_remove_notify_handler(dev);
  	mutex_unlock(&video->device_list_lock);
  
  	acpi_video_bus_stop_devices(video);
  	input_unregister_device(video->input);
  	video->input = NULL;
  }
  
  static int acpi_video_bus_put_devices(struct acpi_video_bus *video)
  {
  	struct acpi_video_device *dev, *next;
  
  	mutex_lock(&video->device_list_lock);
  	list_for_each_entry_safe(dev, next, &video->video_device_list, entry) {
  		list_del(&dev->entry);
  		kfree(dev);
  	}
  	mutex_unlock(&video->device_list_lock);
  
  	return 0;
  }
  
  static int instance;
  
  static int acpi_video_bus_add(struct acpi_device *device)
  {
  	struct acpi_video_bus *video;
  	int error;
  	acpi_status status;
  
  	status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
  				device->parent->handle, 1,
  				acpi_video_bus_match, NULL,
  				device, NULL);
  	if (status == AE_ALREADY_EXISTS) {
  		printk(KERN_WARNING FW_BUG
  			"Duplicate ACPI video bus devices for the"
  			" same VGA controller, please try module "
  			"parameter \"video.allow_duplicates=1\""
  			"if the current driver doesn't work.\n");
  		if (!allow_duplicates)
  			return -ENODEV;
  	}
  
  	video = kzalloc(sizeof(struct acpi_video_bus), GFP_KERNEL);
  	if (!video)
  		return -ENOMEM;
  
  	/* a hack to fix the duplicate name "VID" problem on T61 */
  	if (!strcmp(device->pnp.bus_id, "VID")) {
  		if (instance)
  			device->pnp.bus_id[3] = '0' + instance;
  		instance++;
  	}
  	/* a hack to fix the duplicate name "VGA" problem on Pa 3553 */
  	if (!strcmp(device->pnp.bus_id, "VGA")) {
  		if (instance)
  			device->pnp.bus_id[3] = '0' + instance;
  		instance++;
  	}
  
  	video->device = device;
  	strcpy(acpi_device_name(device), ACPI_VIDEO_BUS_NAME);
  	strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);
  	device->driver_data = video;
  
  	acpi_video_bus_find_cap(video);
  	error = acpi_video_bus_check(video);
  	if (error)
  		goto err_free_video;
  
  	mutex_init(&video->device_list_lock);
  	INIT_LIST_HEAD(&video->video_device_list);
  
  	error = acpi_video_bus_get_devices(video, device);
  	if (error)
  		goto err_put_video;
  
  	printk(KERN_INFO PREFIX "%s [%s] (multi-head: %s  rom: %s  post: %s)\n",
  	       ACPI_VIDEO_DEVICE_NAME, acpi_device_bid(device),
  	       video->flags.multihead ? "yes" : "no",
  	       video->flags.rom ? "yes" : "no",
  	       video->flags.post ? "yes" : "no");
  	mutex_lock(&video_list_lock);
  	list_add_tail(&video->entry, &video_bus_head);
  	mutex_unlock(&video_list_lock);
  
  	acpi_video_bus_register_backlight(video);
  	acpi_video_bus_add_notify_handler(video);
  
  	return 0;
  
  err_put_video:
  	acpi_video_bus_put_devices(video);
  	kfree(video->attached_array);
  err_free_video:
  	kfree(video);
  	device->driver_data = NULL;
  
  	return error;
  }
  
  static int acpi_video_bus_remove(struct acpi_device *device)
  {
  	struct acpi_video_bus *video = NULL;
  
  
  	if (!device || !acpi_driver_data(device))
  		return -EINVAL;
  
  	video = acpi_driver_data(device);
  
  	acpi_video_bus_remove_notify_handler(video);
  	acpi_video_bus_unregister_backlight(video);
  	acpi_video_bus_put_devices(video);
  
  	mutex_lock(&video_list_lock);
  	list_del(&video->entry);
  	mutex_unlock(&video_list_lock);
  
  	kfree(video->attached_array);
  	kfree(video);
  
  	return 0;
  }
  
  static int __init is_i740(struct pci_dev *dev)
  {
  	if (dev->device == 0x00D1)
  		return 1;
  	if (dev->device == 0x7000)
  		return 1;
  	return 0;
  }
  
  static int __init intel_opregion_present(void)
  {
  	int opregion = 0;
  	struct pci_dev *dev = NULL;
  	u32 address;
  
  	for_each_pci_dev(dev) {
  		if ((dev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
  			continue;
  		if (dev->vendor != PCI_VENDOR_ID_INTEL)
  			continue;
  		/* We don't want to poke around undefined i740 registers */
  		if (is_i740(dev))
  			continue;
  		pci_read_config_dword(dev, 0xfc, &address);
  		if (!address)
  			continue;
  		opregion = 1;
  	}
  	return opregion;
  }
  
  static bool dmi_is_desktop(void)
  {
  	const char *chassis_type;
  
  	chassis_type = dmi_get_system_info(DMI_CHASSIS_TYPE);
  	if (!chassis_type)
  		return false;
  
  	if (!strcmp(chassis_type, "3") || /*  3: Desktop */
  	    !strcmp(chassis_type, "4") || /*  4: Low Profile Desktop */
  	    !strcmp(chassis_type, "5") || /*  5: Pizza Box */
  	    !strcmp(chassis_type, "6") || /*  6: Mini Tower */
  	    !strcmp(chassis_type, "7") || /*  7: Tower */
  	    !strcmp(chassis_type, "11"))  /* 11: Main Server Chassis */
  		return true;
  
  	return false;
  }
  
  int acpi_video_register(void)
  {
  	int ret = 0;
  
  	mutex_lock(&register_count_mutex);
  	if (register_count) {
  		/*
  		 * if the function of acpi_video_register is already called,
  		 * don't register the acpi_vide_bus again and return no error.
  		 */
  		goto leave;
  	}
  
  	/*
  	 * We're seeing a lot of bogus backlight interfaces on newer machines
  	 * without a LCD such as desktops, servers and HDMI sticks. Checking
  	 * the lcd flag fixes this, so enable this on any machines which are
  	 * win8 ready (where we also prefer the native backlight driver, so
  	 * normally the acpi_video code should not register there anyways).
  	 */
  	if (only_lcd == -1) {
  		if (dmi_is_desktop() && acpi_osi_is_win8())
  			only_lcd = true;
  		else
  			only_lcd = false;
  	}
  
  	dmi_check_system(video_dmi_table);
  
  	ret = acpi_bus_register_driver(&acpi_video_bus);
  	if (ret)
  		goto leave;
  
  	/*
  	 * When the acpi_video_bus is loaded successfully, increase
  	 * the counter reference.
  	 */
  	register_count = 1;
  
  leave:
  	mutex_unlock(&register_count_mutex);
  	return ret;
  }
  EXPORT_SYMBOL(acpi_video_register);
  
  void acpi_video_unregister(void)
  {
  	mutex_lock(&register_count_mutex);
  	if (register_count) {
  		acpi_bus_unregister_driver(&acpi_video_bus);
  		register_count = 0;
  	}
  	mutex_unlock(&register_count_mutex);
  }
  EXPORT_SYMBOL(acpi_video_unregister);
  
  void acpi_video_unregister_backlight(void)
  {
  	struct acpi_video_bus *video;
  
  	mutex_lock(&register_count_mutex);
  	if (register_count) {
  		mutex_lock(&video_list_lock);
  		list_for_each_entry(video, &video_bus_head, entry)
  			acpi_video_bus_unregister_backlight(video);
  		mutex_unlock(&video_list_lock);
  	}
  	mutex_unlock(&register_count_mutex);
  }
  
  bool acpi_video_handles_brightness_key_presses(void)
  {
  	bool have_video_busses;
  
  	mutex_lock(&video_list_lock);
  	have_video_busses = !list_empty(&video_bus_head);
  	mutex_unlock(&video_list_lock);
  
  	return have_video_busses &&
  	       (report_key_events & REPORT_BRIGHTNESS_KEY_EVENTS);
  }
  EXPORT_SYMBOL(acpi_video_handles_brightness_key_presses);
  
  /*
   * This is kind of nasty. Hardware using Intel chipsets may require
   * the video opregion code to be run first in order to initialise
   * state before any ACPI video calls are made. To handle this we defer
   * registration of the video class until the opregion code has run.
   */
  
  static int __init acpi_video_init(void)
  {
  	/*
  	 * Let the module load even if ACPI is disabled (e.g. due to
  	 * a broken BIOS) so that i915.ko can still be loaded on such
  	 * old systems without an AcpiOpRegion.
  	 *
  	 * acpi_video_register() will report -ENODEV later as well due
  	 * to acpi_disabled when i915.ko tries to register itself afterwards.
  	 */
  	if (acpi_disabled)
  		return 0;
  
  	if (intel_opregion_present())
  		return 0;
  
  	return acpi_video_register();
  }
  
  static void __exit acpi_video_exit(void)
  {
  	acpi_video_detect_exit();
  	acpi_video_unregister();
  
  	return;
  }
  
  module_init(acpi_video_init);
  module_exit(acpi_video_exit);
  