1/*
2 *  video.c - ACPI Video Driver
3 *
4 *  Copyright (C) 2004 Luming Yu <luming.yu@intel.com>
5 *  Copyright (C) 2004 Bruno Ducrot <ducrot@poupinou.org>
6 *  Copyright (C) 2006 Thomas Tuttle <linux-kernel@ttuttle.net>
7 *
8 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
9 *
10 *  This program is free software; you can redistribute it and/or modify
11 *  it under the terms of the GNU General Public License as published by
12 *  the Free Software Foundation; either version 2 of the License, or (at
13 *  your option) any later version.
14 *
15 *  This program is distributed in the hope that it will be useful, but
16 *  WITHOUT ANY WARRANTY; without even the implied warranty of
17 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18 *  General Public License for more details.
19 *
20 *  You should have received a copy of the GNU General Public License along
21 *  with this program; if not, write to the Free Software Foundation, Inc.,
22 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
23 *
24 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
25 */
26
27#include <linux/kernel.h>
28#include <linux/module.h>
29#include <linux/init.h>
30#include <linux/types.h>
31#include <linux/list.h>
32#include <linux/mutex.h>
33#include <linux/input.h>
34#include <linux/backlight.h>
35#include <linux/thermal.h>
36#include <linux/sort.h>
37#include <linux/pci.h>
38#include <linux/pci_ids.h>
39#include <linux/slab.h>
40#include <linux/dmi.h>
41#include <linux/suspend.h>
42#include <linux/acpi.h>
43#include <acpi/video.h>
44#include <asm/uaccess.h>
45
46#include "internal.h"
47
48#define ACPI_VIDEO_BUS_NAME		"Video Bus"
49#define ACPI_VIDEO_DEVICE_NAME		"Video Device"
50#define ACPI_VIDEO_NOTIFY_SWITCH	0x80
51#define ACPI_VIDEO_NOTIFY_PROBE		0x81
52#define ACPI_VIDEO_NOTIFY_CYCLE		0x82
53#define ACPI_VIDEO_NOTIFY_NEXT_OUTPUT	0x83
54#define ACPI_VIDEO_NOTIFY_PREV_OUTPUT	0x84
55
56#define ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS	0x85
57#define	ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS	0x86
58#define ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS	0x87
59#define ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS	0x88
60#define ACPI_VIDEO_NOTIFY_DISPLAY_OFF		0x89
61
62#define MAX_NAME_LEN	20
63
64#define _COMPONENT		ACPI_VIDEO_COMPONENT
65ACPI_MODULE_NAME("video");
66
67MODULE_AUTHOR("Bruno Ducrot");
68MODULE_DESCRIPTION("ACPI Video Driver");
69MODULE_LICENSE("GPL");
70
71static bool brightness_switch_enabled = 1;
72module_param(brightness_switch_enabled, bool, 0644);
73
74/*
75 * By default, we don't allow duplicate ACPI video bus devices
76 * under the same VGA controller
77 */
78static bool allow_duplicates;
79module_param(allow_duplicates, bool, 0644);
80
81/*
82 * For Windows 8 systems: used to decide if video module
83 * should skip registering backlight interface of its own.
84 */
85enum {
86	NATIVE_BACKLIGHT_NOT_SET = -1,
87	NATIVE_BACKLIGHT_OFF,
88	NATIVE_BACKLIGHT_ON,
89};
90
91static int use_native_backlight_param = NATIVE_BACKLIGHT_NOT_SET;
92module_param_named(use_native_backlight, use_native_backlight_param, int, 0444);
93static int use_native_backlight_dmi = NATIVE_BACKLIGHT_NOT_SET;
94
95static int register_count;
96static struct mutex video_list_lock;
97static struct list_head video_bus_head;
98static int acpi_video_bus_add(struct acpi_device *device);
99static int acpi_video_bus_remove(struct acpi_device *device);
100static void acpi_video_bus_notify(struct acpi_device *device, u32 event);
101
102static const struct acpi_device_id video_device_ids[] = {
103	{ACPI_VIDEO_HID, 0},
104	{"", 0},
105};
106MODULE_DEVICE_TABLE(acpi, video_device_ids);
107
108static struct acpi_driver acpi_video_bus = {
109	.name = "video",
110	.class = ACPI_VIDEO_CLASS,
111	.ids = video_device_ids,
112	.ops = {
113		.add = acpi_video_bus_add,
114		.remove = acpi_video_bus_remove,
115		.notify = acpi_video_bus_notify,
116		},
117};
118
119struct acpi_video_bus_flags {
120	u8 multihead:1;		/* can switch video heads */
121	u8 rom:1;		/* can retrieve a video rom */
122	u8 post:1;		/* can configure the head to */
123	u8 reserved:5;
124};
125
126struct acpi_video_bus_cap {
127	u8 _DOS:1;		/* Enable/Disable output switching */
128	u8 _DOD:1;		/* Enumerate all devices attached to display adapter */
129	u8 _ROM:1;		/* Get ROM Data */
130	u8 _GPD:1;		/* Get POST Device */
131	u8 _SPD:1;		/* Set POST Device */
132	u8 _VPO:1;		/* Video POST Options */
133	u8 reserved:2;
134};
135
136struct acpi_video_device_attrib {
137	u32 display_index:4;	/* A zero-based instance of the Display */
138	u32 display_port_attachment:4;	/* This field differentiates the display type */
139	u32 display_type:4;	/* Describe the specific type in use */
140	u32 vendor_specific:4;	/* Chipset Vendor Specific */
141	u32 bios_can_detect:1;	/* BIOS can detect the device */
142	u32 depend_on_vga:1;	/* Non-VGA output device whose power is related to
143				   the VGA device. */
144	u32 pipe_id:3;		/* For VGA multiple-head devices. */
145	u32 reserved:10;	/* Must be 0 */
146	u32 device_id_scheme:1;	/* Device ID Scheme */
147};
148
149struct acpi_video_enumerated_device {
150	union {
151		u32 int_val;
152		struct acpi_video_device_attrib attrib;
153	} value;
154	struct acpi_video_device *bind_info;
155};
156
157struct acpi_video_bus {
158	struct acpi_device *device;
159	bool backlight_registered;
160	bool backlight_notifier_registered;
161	u8 dos_setting;
162	struct acpi_video_enumerated_device *attached_array;
163	u8 attached_count;
164	u8 child_count;
165	struct acpi_video_bus_cap cap;
166	struct acpi_video_bus_flags flags;
167	struct list_head video_device_list;
168	struct mutex device_list_lock;	/* protects video_device_list */
169	struct list_head entry;
170	struct input_dev *input;
171	char phys[32];	/* for input device */
172	struct notifier_block pm_nb;
173	struct notifier_block backlight_nb;
174};
175
176struct acpi_video_device_flags {
177	u8 crt:1;
178	u8 lcd:1;
179	u8 tvout:1;
180	u8 dvi:1;
181	u8 bios:1;
182	u8 unknown:1;
183	u8 notify:1;
184	u8 reserved:1;
185};
186
187struct acpi_video_device_cap {
188	u8 _ADR:1;		/* Return the unique ID */
189	u8 _BCL:1;		/* Query list of brightness control levels supported */
190	u8 _BCM:1;		/* Set the brightness level */
191	u8 _BQC:1;		/* Get current brightness level */
192	u8 _BCQ:1;		/* Some buggy BIOS uses _BCQ instead of _BQC */
193	u8 _DDC:1;		/* Return the EDID for this device */
194};
195
196struct acpi_video_brightness_flags {
197	u8 _BCL_no_ac_battery_levels:1;	/* no AC/Battery levels in _BCL */
198	u8 _BCL_reversed:1;		/* _BCL package is in a reversed order */
199	u8 _BQC_use_index:1;		/* _BQC returns an index value */
200};
201
202struct acpi_video_device_brightness {
203	int curr;
204	int count;
205	int *levels;
206	struct acpi_video_brightness_flags flags;
207};
208
209struct acpi_video_device {
210	unsigned long device_id;
211	struct acpi_video_device_flags flags;
212	struct acpi_video_device_cap cap;
213	struct list_head entry;
214	struct delayed_work switch_brightness_work;
215	int switch_brightness_event;
216	struct acpi_video_bus *video;
217	struct acpi_device *dev;
218	struct acpi_video_device_brightness *brightness;
219	struct backlight_device *backlight;
220	struct thermal_cooling_device *cooling_dev;
221};
222
223static const char device_decode[][30] = {
224	"motherboard VGA device",
225	"PCI VGA device",
226	"AGP VGA device",
227	"UNKNOWN",
228};
229
230static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data);
231static void acpi_video_device_rebind(struct acpi_video_bus *video);
232static void acpi_video_device_bind(struct acpi_video_bus *video,
233				   struct acpi_video_device *device);
234static int acpi_video_device_enumerate(struct acpi_video_bus *video);
235static int acpi_video_device_lcd_set_level(struct acpi_video_device *device,
236			int level);
237static int acpi_video_device_lcd_get_level_current(
238			struct acpi_video_device *device,
239			unsigned long long *level, bool raw);
240static int acpi_video_get_next_level(struct acpi_video_device *device,
241				     u32 level_current, u32 event);
242static void acpi_video_switch_brightness(struct work_struct *work);
243
244static bool acpi_video_use_native_backlight(void)
245{
246	if (use_native_backlight_param != NATIVE_BACKLIGHT_NOT_SET)
247		return use_native_backlight_param;
248	else if (use_native_backlight_dmi != NATIVE_BACKLIGHT_NOT_SET)
249		return use_native_backlight_dmi;
250	return acpi_osi_is_win8();
251}
252
253bool acpi_video_verify_backlight_support(void)
254{
255	if (acpi_video_use_native_backlight() &&
256	    backlight_device_registered(BACKLIGHT_RAW))
257		return false;
258	return acpi_video_backlight_support();
259}
260EXPORT_SYMBOL_GPL(acpi_video_verify_backlight_support);
261
262/* backlight device sysfs support */
263static int acpi_video_get_brightness(struct backlight_device *bd)
264{
265	unsigned long long cur_level;
266	int i;
267	struct acpi_video_device *vd = bl_get_data(bd);
268
269	if (acpi_video_device_lcd_get_level_current(vd, &cur_level, false))
270		return -EINVAL;
271	for (i = 2; i < vd->brightness->count; i++) {
272		if (vd->brightness->levels[i] == cur_level)
273			/*
274			 * The first two entries are special - see page 575
275			 * of the ACPI spec 3.0
276			 */
277			return i - 2;
278	}
279	return 0;
280}
281
282static int acpi_video_set_brightness(struct backlight_device *bd)
283{
284	int request_level = bd->props.brightness + 2;
285	struct acpi_video_device *vd = bl_get_data(bd);
286
287	cancel_delayed_work(&vd->switch_brightness_work);
288	return acpi_video_device_lcd_set_level(vd,
289				vd->brightness->levels[request_level]);
290}
291
292static const struct backlight_ops acpi_backlight_ops = {
293	.get_brightness = acpi_video_get_brightness,
294	.update_status  = acpi_video_set_brightness,
295};
296
297/* thermal cooling device callbacks */
298static int video_get_max_state(struct thermal_cooling_device *cooling_dev, unsigned
299			       long *state)
300{
301	struct acpi_device *device = cooling_dev->devdata;
302	struct acpi_video_device *video = acpi_driver_data(device);
303
304	*state = video->brightness->count - 3;
305	return 0;
306}
307
308static int video_get_cur_state(struct thermal_cooling_device *cooling_dev, unsigned
309			       long *state)
310{
311	struct acpi_device *device = cooling_dev->devdata;
312	struct acpi_video_device *video = acpi_driver_data(device);
313	unsigned long long level;
314	int offset;
315
316	if (acpi_video_device_lcd_get_level_current(video, &level, false))
317		return -EINVAL;
318	for (offset = 2; offset < video->brightness->count; offset++)
319		if (level == video->brightness->levels[offset]) {
320			*state = video->brightness->count - offset - 1;
321			return 0;
322		}
323
324	return -EINVAL;
325}
326
327static int
328video_set_cur_state(struct thermal_cooling_device *cooling_dev, unsigned long state)
329{
330	struct acpi_device *device = cooling_dev->devdata;
331	struct acpi_video_device *video = acpi_driver_data(device);
332	int level;
333
334	if (state >= video->brightness->count - 2)
335		return -EINVAL;
336
337	state = video->brightness->count - state;
338	level = video->brightness->levels[state - 1];
339	return acpi_video_device_lcd_set_level(video, level);
340}
341
342static const struct thermal_cooling_device_ops video_cooling_ops = {
343	.get_max_state = video_get_max_state,
344	.get_cur_state = video_get_cur_state,
345	.set_cur_state = video_set_cur_state,
346};
347
348/*
349 * --------------------------------------------------------------------------
350 *                             Video Management
351 * --------------------------------------------------------------------------
352 */
353
354static int
355acpi_video_device_lcd_query_levels(struct acpi_video_device *device,
356				   union acpi_object **levels)
357{
358	int status;
359	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
360	union acpi_object *obj;
361
362
363	*levels = NULL;
364
365	status = acpi_evaluate_object(device->dev->handle, "_BCL", NULL, &buffer);
366	if (!ACPI_SUCCESS(status))
367		return status;
368	obj = (union acpi_object *)buffer.pointer;
369	if (!obj || (obj->type != ACPI_TYPE_PACKAGE)) {
370		printk(KERN_ERR PREFIX "Invalid _BCL data\n");
371		status = -EFAULT;
372		goto err;
373	}
374
375	*levels = obj;
376
377	return 0;
378
379err:
380	kfree(buffer.pointer);
381
382	return status;
383}
384
385static int
386acpi_video_device_lcd_set_level(struct acpi_video_device *device, int level)
387{
388	int status;
389	int state;
390
391	status = acpi_execute_simple_method(device->dev->handle,
392					    "_BCM", level);
393	if (ACPI_FAILURE(status)) {
394		ACPI_ERROR((AE_INFO, "Evaluating _BCM failed"));
395		return -EIO;
396	}
397
398	device->brightness->curr = level;
399	for (state = 2; state < device->brightness->count; state++)
400		if (level == device->brightness->levels[state]) {
401			if (device->backlight)
402				device->backlight->props.brightness = state - 2;
403			return 0;
404		}
405
406	ACPI_ERROR((AE_INFO, "Current brightness invalid"));
407	return -EINVAL;
408}
409
410/*
411 * For some buggy _BQC methods, we need to add a constant value to
412 * the _BQC return value to get the actual current brightness level
413 */
414
415static int bqc_offset_aml_bug_workaround;
416static int __init video_set_bqc_offset(const struct dmi_system_id *d)
417{
418	bqc_offset_aml_bug_workaround = 9;
419	return 0;
420}
421
422static int __init video_disable_native_backlight(const struct dmi_system_id *d)
423{
424	use_native_backlight_dmi = NATIVE_BACKLIGHT_OFF;
425	return 0;
426}
427
428static int __init video_enable_native_backlight(const struct dmi_system_id *d)
429{
430	use_native_backlight_dmi = NATIVE_BACKLIGHT_ON;
431	return 0;
432}
433
434static struct dmi_system_id video_dmi_table[] __initdata = {
435	/*
436	 * Broken _BQC workaround http://bugzilla.kernel.org/show_bug.cgi?id=13121
437	 */
438	{
439	 .callback = video_set_bqc_offset,
440	 .ident = "Acer Aspire 5720",
441	 .matches = {
442		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
443		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5720"),
444		},
445	},
446	{
447	 .callback = video_set_bqc_offset,
448	 .ident = "Acer Aspire 5710Z",
449	 .matches = {
450		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
451		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5710Z"),
452		},
453	},
454	{
455	 .callback = video_set_bqc_offset,
456	 .ident = "eMachines E510",
457	 .matches = {
458		DMI_MATCH(DMI_BOARD_VENDOR, "EMACHINES"),
459		DMI_MATCH(DMI_PRODUCT_NAME, "eMachines E510"),
460		},
461	},
462	{
463	 .callback = video_set_bqc_offset,
464	 .ident = "Acer Aspire 5315",
465	 .matches = {
466		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
467		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5315"),
468		},
469	},
470	{
471	 .callback = video_set_bqc_offset,
472	 .ident = "Acer Aspire 7720",
473	 .matches = {
474		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
475		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 7720"),
476		},
477	},
478
479	/*
480	 * These models have a working acpi_video backlight control, and using
481	 * native backlight causes a regression where backlight does not work
482	 * when userspace is not handling brightness key events. Disable
483	 * native_backlight on these to fix this:
484	 * https://bugzilla.kernel.org/show_bug.cgi?id=81691
485	 */
486	{
487	 .callback = video_disable_native_backlight,
488	 .ident = "ThinkPad T420",
489	 .matches = {
490		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
491		DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T420"),
492		},
493	},
494	{
495	 .callback = video_disable_native_backlight,
496	 .ident = "ThinkPad T520",
497	 .matches = {
498		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
499		DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T520"),
500		},
501	},
502	{
503	 .callback = video_disable_native_backlight,
504	 .ident = "ThinkPad X201s",
505	 .matches = {
506		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
507		DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X201s"),
508		},
509	},
510
511	/* The native backlight controls do not work on some older machines */
512	{
513	 /* https://bugs.freedesktop.org/show_bug.cgi?id=81515 */
514	 .callback = video_disable_native_backlight,
515	 .ident = "HP ENVY 15 Notebook",
516	 .matches = {
517		DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
518		DMI_MATCH(DMI_PRODUCT_NAME, "HP ENVY 15 Notebook PC"),
519		},
520	},
521
522	{
523	 .callback = video_disable_native_backlight,
524	 .ident = "SAMSUNG 870Z5E/880Z5E/680Z5E",
525	 .matches = {
526		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
527		DMI_MATCH(DMI_PRODUCT_NAME, "870Z5E/880Z5E/680Z5E"),
528		},
529	},
530	{
531	 .callback = video_disable_native_backlight,
532	 .ident = "SAMSUNG 370R4E/370R4V/370R5E/3570RE/370R5V",
533	 .matches = {
534		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
535		DMI_MATCH(DMI_PRODUCT_NAME, "370R4E/370R4V/370R5E/3570RE/370R5V"),
536		},
537	},
538	{
539	 /* https://bugzilla.redhat.com/show_bug.cgi?id=1186097 */
540	 .callback = video_disable_native_backlight,
541	 .ident = "SAMSUNG 3570R/370R/470R/450R/510R/4450RV",
542	 .matches = {
543		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
544		DMI_MATCH(DMI_PRODUCT_NAME, "3570R/370R/470R/450R/510R/4450RV"),
545		},
546	},
547	{
548	 /* https://bugzilla.redhat.com/show_bug.cgi?id=1094948 */
549	 .callback = video_disable_native_backlight,
550	 .ident = "SAMSUNG 730U3E/740U3E",
551	 .matches = {
552		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
553		DMI_MATCH(DMI_PRODUCT_NAME, "730U3E/740U3E"),
554		},
555	},
556	{
557	 /* https://bugs.freedesktop.org/show_bug.cgi?id=87286 */
558	 .callback = video_disable_native_backlight,
559	 .ident = "SAMSUNG 900X3C/900X3D/900X3E/900X4C/900X4D",
560	 .matches = {
561		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
562		DMI_MATCH(DMI_PRODUCT_NAME, "900X3C/900X3D/900X3E/900X4C/900X4D"),
563		},
564	},
565
566	{
567	 /* https://bugzilla.redhat.com/show_bug.cgi?id=1163574 */
568	 .callback = video_disable_native_backlight,
569	 .ident = "Dell XPS15 L521X",
570	 .matches = {
571		DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
572		DMI_MATCH(DMI_PRODUCT_NAME, "XPS L521X"),
573		},
574	},
575
576	/* Non win8 machines which need native backlight nevertheless */
577	{
578	 /* https://bugzilla.redhat.com/show_bug.cgi?id=1187004 */
579	 .callback = video_enable_native_backlight,
580	 .ident = "Lenovo Ideapad Z570",
581	 .matches = {
582		DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
583		DMI_MATCH(DMI_PRODUCT_NAME, "102434U"),
584		},
585	},
586	{}
587};
588
589static unsigned long long
590acpi_video_bqc_value_to_level(struct acpi_video_device *device,
591			      unsigned long long bqc_value)
592{
593	unsigned long long level;
594
595	if (device->brightness->flags._BQC_use_index) {
596		/*
597		 * _BQC returns an index that doesn't account for
598		 * the first 2 items with special meaning, so we need
599		 * to compensate for that by offsetting ourselves
600		 */
601		if (device->brightness->flags._BCL_reversed)
602			bqc_value = device->brightness->count - 3 - bqc_value;
603
604		level = device->brightness->levels[bqc_value + 2];
605	} else {
606		level = bqc_value;
607	}
608
609	level += bqc_offset_aml_bug_workaround;
610
611	return level;
612}
613
614static int
615acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
616					unsigned long long *level, bool raw)
617{
618	acpi_status status = AE_OK;
619	int i;
620
621	if (device->cap._BQC || device->cap._BCQ) {
622		char *buf = device->cap._BQC ? "_BQC" : "_BCQ";
623
624		status = acpi_evaluate_integer(device->dev->handle, buf,
625						NULL, level);
626		if (ACPI_SUCCESS(status)) {
627			if (raw) {
628				/*
629				 * Caller has indicated he wants the raw
630				 * value returned by _BQC, so don't furtherly
631				 * mess with the value.
632				 */
633				return 0;
634			}
635
636			*level = acpi_video_bqc_value_to_level(device, *level);
637
638			for (i = 2; i < device->brightness->count; i++)
639				if (device->brightness->levels[i] == *level) {
640					device->brightness->curr = *level;
641					return 0;
642				}
643			/*
644			 * BQC returned an invalid level.
645			 * Stop using it.
646			 */
647			ACPI_WARNING((AE_INFO,
648				      "%s returned an invalid level",
649				      buf));
650			device->cap._BQC = device->cap._BCQ = 0;
651		} else {
652			/*
653			 * Fixme:
654			 * should we return an error or ignore this failure?
655			 * dev->brightness->curr is a cached value which stores
656			 * the correct current backlight level in most cases.
657			 * ACPI video backlight still works w/ buggy _BQC.
658			 * http://bugzilla.kernel.org/show_bug.cgi?id=12233
659			 */
660			ACPI_WARNING((AE_INFO, "Evaluating %s failed", buf));
661			device->cap._BQC = device->cap._BCQ = 0;
662		}
663	}
664
665	*level = device->brightness->curr;
666	return 0;
667}
668
669static int
670acpi_video_device_EDID(struct acpi_video_device *device,
671		       union acpi_object **edid, ssize_t length)
672{
673	int status;
674	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
675	union acpi_object *obj;
676	union acpi_object arg0 = { ACPI_TYPE_INTEGER };
677	struct acpi_object_list args = { 1, &arg0 };
678
679
680	*edid = NULL;
681
682	if (!device)
683		return -ENODEV;
684	if (length == 128)
685		arg0.integer.value = 1;
686	else if (length == 256)
687		arg0.integer.value = 2;
688	else
689		return -EINVAL;
690
691	status = acpi_evaluate_object(device->dev->handle, "_DDC", &args, &buffer);
692	if (ACPI_FAILURE(status))
693		return -ENODEV;
694
695	obj = buffer.pointer;
696
697	if (obj && obj->type == ACPI_TYPE_BUFFER)
698		*edid = obj;
699	else {
700		printk(KERN_ERR PREFIX "Invalid _DDC data\n");
701		status = -EFAULT;
702		kfree(obj);
703	}
704
705	return status;
706}
707
708/* bus */
709
710/*
711 *  Arg:
712 *	video		: video bus device pointer
713 *	bios_flag	:
714 *		0.	The system BIOS should NOT automatically switch(toggle)
715 *			the active display output.
716 *		1.	The system BIOS should automatically switch (toggle) the
717 *			active display output. No switch event.
718 *		2.	The _DGS value should be locked.
719 *		3.	The system BIOS should not automatically switch (toggle) the
720 *			active display output, but instead generate the display switch
721 *			event notify code.
722 *	lcd_flag	:
723 *		0.	The system BIOS should automatically control the brightness level
724 *			of the LCD when the power changes from AC to DC
725 *		1.	The system BIOS should NOT automatically control the brightness
726 *			level of the LCD when the power changes from AC to DC.
727 *  Return Value:
728 *		-EINVAL	wrong arg.
729 */
730
731static int
732acpi_video_bus_DOS(struct acpi_video_bus *video, int bios_flag, int lcd_flag)
733{
734	acpi_status status;
735
736	if (!video->cap._DOS)
737		return 0;
738
739	if (bios_flag < 0 || bios_flag > 3 || lcd_flag < 0 || lcd_flag > 1)
740		return -EINVAL;
741	video->dos_setting = (lcd_flag << 2) | bios_flag;
742	status = acpi_execute_simple_method(video->device->handle, "_DOS",
743					    (lcd_flag << 2) | bios_flag);
744	if (ACPI_FAILURE(status))
745		return -EIO;
746
747	return 0;
748}
749
750/*
751 * Simple comparison function used to sort backlight levels.
752 */
753
754static int
755acpi_video_cmp_level(const void *a, const void *b)
756{
757	return *(int *)a - *(int *)b;
758}
759
760/*
761 * Decides if _BQC/_BCQ for this system is usable
762 *
763 * We do this by changing the level first and then read out the current
764 * brightness level, if the value does not match, find out if it is using
765 * index. If not, clear the _BQC/_BCQ capability.
766 */
767static int acpi_video_bqc_quirk(struct acpi_video_device *device,
768				int max_level, int current_level)
769{
770	struct acpi_video_device_brightness *br = device->brightness;
771	int result;
772	unsigned long long level;
773	int test_level;
774
775	/* don't mess with existing known broken systems */
776	if (bqc_offset_aml_bug_workaround)
777		return 0;
778
779	/*
780	 * Some systems always report current brightness level as maximum
781	 * through _BQC, we need to test another value for them.
782	 */
783	test_level = current_level == max_level ? br->levels[3] : max_level;
784
785	result = acpi_video_device_lcd_set_level(device, test_level);
786	if (result)
787		return result;
788
789	result = acpi_video_device_lcd_get_level_current(device, &level, true);
790	if (result)
791		return result;
792
793	if (level != test_level) {
794		/* buggy _BQC found, need to find out if it uses index */
795		if (level < br->count) {
796			if (br->flags._BCL_reversed)
797				level = br->count - 3 - level;
798			if (br->levels[level + 2] == test_level)
799				br->flags._BQC_use_index = 1;
800		}
801
802		if (!br->flags._BQC_use_index)
803			device->cap._BQC = device->cap._BCQ = 0;
804	}
805
806	return 0;
807}
808
809
810/*
811 *  Arg:
812 *	device	: video output device (LCD, CRT, ..)
813 *
814 *  Return Value:
815 *	Maximum brightness level
816 *
817 *  Allocate and initialize device->brightness.
818 */
819
820static int
821acpi_video_init_brightness(struct acpi_video_device *device)
822{
823	union acpi_object *obj = NULL;
824	int i, max_level = 0, count = 0, level_ac_battery = 0;
825	unsigned long long level, level_old;
826	union acpi_object *o;
827	struct acpi_video_device_brightness *br = NULL;
828	int result = -EINVAL;
829	u32 value;
830
831	if (!ACPI_SUCCESS(acpi_video_device_lcd_query_levels(device, &obj))) {
832		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Could not query available "
833						"LCD brightness level\n"));
834		goto out;
835	}
836
837	if (obj->package.count < 2)
838		goto out;
839
840	br = kzalloc(sizeof(*br), GFP_KERNEL);
841	if (!br) {
842		printk(KERN_ERR "can't allocate memory\n");
843		result = -ENOMEM;
844		goto out;
845	}
846
847	br->levels = kmalloc((obj->package.count + 2) * sizeof *(br->levels),
848				GFP_KERNEL);
849	if (!br->levels) {
850		result = -ENOMEM;
851		goto out_free;
852	}
853
854	for (i = 0; i < obj->package.count; i++) {
855		o = (union acpi_object *)&obj->package.elements[i];
856		if (o->type != ACPI_TYPE_INTEGER) {
857			printk(KERN_ERR PREFIX "Invalid data\n");
858			continue;
859		}
860		value = (u32) o->integer.value;
861		/* Skip duplicate entries */
862		if (count > 2 && br->levels[count - 1] == value)
863			continue;
864
865		br->levels[count] = value;
866
867		if (br->levels[count] > max_level)
868			max_level = br->levels[count];
869		count++;
870	}
871
872	/*
873	 * some buggy BIOS don't export the levels
874	 * when machine is on AC/Battery in _BCL package.
875	 * In this case, the first two elements in _BCL packages
876	 * are also supported brightness levels that OS should take care of.
877	 */
878	for (i = 2; i < count; i++) {
879		if (br->levels[i] == br->levels[0])
880			level_ac_battery++;
881		if (br->levels[i] == br->levels[1])
882			level_ac_battery++;
883	}
884
885	if (level_ac_battery < 2) {
886		level_ac_battery = 2 - level_ac_battery;
887		br->flags._BCL_no_ac_battery_levels = 1;
888		for (i = (count - 1 + level_ac_battery); i >= 2; i--)
889			br->levels[i] = br->levels[i - level_ac_battery];
890		count += level_ac_battery;
891	} else if (level_ac_battery > 2)
892		ACPI_ERROR((AE_INFO, "Too many duplicates in _BCL package"));
893
894	/* Check if the _BCL package is in a reversed order */
895	if (max_level == br->levels[2]) {
896		br->flags._BCL_reversed = 1;
897		sort(&br->levels[2], count - 2, sizeof(br->levels[2]),
898			acpi_video_cmp_level, NULL);
899	} else if (max_level != br->levels[count - 1])
900		ACPI_ERROR((AE_INFO,
901			    "Found unordered _BCL package"));
902
903	br->count = count;
904	device->brightness = br;
905
906	/* _BQC uses INDEX while _BCL uses VALUE in some laptops */
907	br->curr = level = max_level;
908
909	if (!device->cap._BQC)
910		goto set_level;
911
912	result = acpi_video_device_lcd_get_level_current(device,
913							 &level_old, true);
914	if (result)
915		goto out_free_levels;
916
917	result = acpi_video_bqc_quirk(device, max_level, level_old);
918	if (result)
919		goto out_free_levels;
920	/*
921	 * cap._BQC may get cleared due to _BQC is found to be broken
922	 * in acpi_video_bqc_quirk, so check again here.
923	 */
924	if (!device->cap._BQC)
925		goto set_level;
926
927	level = acpi_video_bqc_value_to_level(device, level_old);
928	/*
929	 * On some buggy laptops, _BQC returns an uninitialized
930	 * value when invoked for the first time, i.e.
931	 * level_old is invalid (no matter whether it's a level
932	 * or an index). Set the backlight to max_level in this case.
933	 */
934	for (i = 2; i < br->count; i++)
935		if (level == br->levels[i])
936			break;
937	if (i == br->count || !level)
938		level = max_level;
939
940set_level:
941	result = acpi_video_device_lcd_set_level(device, level);
942	if (result)
943		goto out_free_levels;
944
945	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
946			  "found %d brightness levels\n", count - 2));
947	kfree(obj);
948	return result;
949
950out_free_levels:
951	kfree(br->levels);
952out_free:
953	kfree(br);
954out:
955	device->brightness = NULL;
956	kfree(obj);
957	return result;
958}
959
960/*
961 *  Arg:
962 *	device	: video output device (LCD, CRT, ..)
963 *
964 *  Return Value:
965 *	None
966 *
967 *  Find out all required AML methods defined under the output
968 *  device.
969 */
970
971static void acpi_video_device_find_cap(struct acpi_video_device *device)
972{
973	if (acpi_has_method(device->dev->handle, "_ADR"))
974		device->cap._ADR = 1;
975	if (acpi_has_method(device->dev->handle, "_BCL"))
976		device->cap._BCL = 1;
977	if (acpi_has_method(device->dev->handle, "_BCM"))
978		device->cap._BCM = 1;
979	if (acpi_has_method(device->dev->handle, "_BQC")) {
980		device->cap._BQC = 1;
981	} else if (acpi_has_method(device->dev->handle, "_BCQ")) {
982		printk(KERN_WARNING FW_BUG "_BCQ is used instead of _BQC\n");
983		device->cap._BCQ = 1;
984	}
985
986	if (acpi_has_method(device->dev->handle, "_DDC"))
987		device->cap._DDC = 1;
988}
989
990/*
991 *  Arg:
992 *	device	: video output device (VGA)
993 *
994 *  Return Value:
995 *	None
996 *
997 *  Find out all required AML methods defined under the video bus device.
998 */
999
1000static void acpi_video_bus_find_cap(struct acpi_video_bus *video)
1001{
1002	if (acpi_has_method(video->device->handle, "_DOS"))
1003		video->cap._DOS = 1;
1004	if (acpi_has_method(video->device->handle, "_DOD"))
1005		video->cap._DOD = 1;
1006	if (acpi_has_method(video->device->handle, "_ROM"))
1007		video->cap._ROM = 1;
1008	if (acpi_has_method(video->device->handle, "_GPD"))
1009		video->cap._GPD = 1;
1010	if (acpi_has_method(video->device->handle, "_SPD"))
1011		video->cap._SPD = 1;
1012	if (acpi_has_method(video->device->handle, "_VPO"))
1013		video->cap._VPO = 1;
1014}
1015
1016/*
1017 * Check whether the video bus device has required AML method to
1018 * support the desired features
1019 */
1020
1021static int acpi_video_bus_check(struct acpi_video_bus *video)
1022{
1023	acpi_status status = -ENOENT;
1024	struct pci_dev *dev;
1025
1026	if (!video)
1027		return -EINVAL;
1028
1029	dev = acpi_get_pci_dev(video->device->handle);
1030	if (!dev)
1031		return -ENODEV;
1032	pci_dev_put(dev);
1033
1034	/*
1035	 * Since there is no HID, CID and so on for VGA driver, we have
1036	 * to check well known required nodes.
1037	 */
1038
1039	/* Does this device support video switching? */
1040	if (video->cap._DOS || video->cap._DOD) {
1041		if (!video->cap._DOS) {
1042			printk(KERN_WARNING FW_BUG
1043				"ACPI(%s) defines _DOD but not _DOS\n",
1044				acpi_device_bid(video->device));
1045		}
1046		video->flags.multihead = 1;
1047		status = 0;
1048	}
1049
1050	/* Does this device support retrieving a video ROM? */
1051	if (video->cap._ROM) {
1052		video->flags.rom = 1;
1053		status = 0;
1054	}
1055
1056	/* Does this device support configuring which video device to POST? */
1057	if (video->cap._GPD && video->cap._SPD && video->cap._VPO) {
1058		video->flags.post = 1;
1059		status = 0;
1060	}
1061
1062	return status;
1063}
1064
1065/*
1066 * --------------------------------------------------------------------------
1067 *                               Driver Interface
1068 * --------------------------------------------------------------------------
1069 */
1070
1071/* device interface */
1072static struct acpi_video_device_attrib *
1073acpi_video_get_device_attr(struct acpi_video_bus *video, unsigned long device_id)
1074{
1075	struct acpi_video_enumerated_device *ids;
1076	int i;
1077
1078	for (i = 0; i < video->attached_count; i++) {
1079		ids = &video->attached_array[i];
1080		if ((ids->value.int_val & 0xffff) == device_id)
1081			return &ids->value.attrib;
1082	}
1083
1084	return NULL;
1085}
1086
1087static int
1088acpi_video_get_device_type(struct acpi_video_bus *video,
1089			   unsigned long device_id)
1090{
1091	struct acpi_video_enumerated_device *ids;
1092	int i;
1093
1094	for (i = 0; i < video->attached_count; i++) {
1095		ids = &video->attached_array[i];
1096		if ((ids->value.int_val & 0xffff) == device_id)
1097			return ids->value.int_val;
1098	}
1099
1100	return 0;
1101}
1102
1103static int
1104acpi_video_bus_get_one_device(struct acpi_device *device,
1105			      struct acpi_video_bus *video)
1106{
1107	unsigned long long device_id;
1108	int status, device_type;
1109	struct acpi_video_device *data;
1110	struct acpi_video_device_attrib *attribute;
1111
1112	status =
1113	    acpi_evaluate_integer(device->handle, "_ADR", NULL, &device_id);
1114	/* Some device omits _ADR, we skip them instead of fail */
1115	if (ACPI_FAILURE(status))
1116		return 0;
1117
1118	data = kzalloc(sizeof(struct acpi_video_device), GFP_KERNEL);
1119	if (!data)
1120		return -ENOMEM;
1121
1122	strcpy(acpi_device_name(device), ACPI_VIDEO_DEVICE_NAME);
1123	strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);
1124	device->driver_data = data;
1125
1126	data->device_id = device_id;
1127	data->video = video;
1128	data->dev = device;
1129	INIT_DELAYED_WORK(&data->switch_brightness_work,
1130			  acpi_video_switch_brightness);
1131
1132	attribute = acpi_video_get_device_attr(video, device_id);
1133
1134	if (attribute && attribute->device_id_scheme) {
1135		switch (attribute->display_type) {
1136		case ACPI_VIDEO_DISPLAY_CRT:
1137			data->flags.crt = 1;
1138			break;
1139		case ACPI_VIDEO_DISPLAY_TV:
1140			data->flags.tvout = 1;
1141			break;
1142		case ACPI_VIDEO_DISPLAY_DVI:
1143			data->flags.dvi = 1;
1144			break;
1145		case ACPI_VIDEO_DISPLAY_LCD:
1146			data->flags.lcd = 1;
1147			break;
1148		default:
1149			data->flags.unknown = 1;
1150			break;
1151		}
1152		if (attribute->bios_can_detect)
1153			data->flags.bios = 1;
1154	} else {
1155		/* Check for legacy IDs */
1156		device_type = acpi_video_get_device_type(video, device_id);
1157		/* Ignore bits 16 and 18-20 */
1158		switch (device_type & 0xffe2ffff) {
1159		case ACPI_VIDEO_DISPLAY_LEGACY_MONITOR:
1160			data->flags.crt = 1;
1161			break;
1162		case ACPI_VIDEO_DISPLAY_LEGACY_PANEL:
1163			data->flags.lcd = 1;
1164			break;
1165		case ACPI_VIDEO_DISPLAY_LEGACY_TV:
1166			data->flags.tvout = 1;
1167			break;
1168		default:
1169			data->flags.unknown = 1;
1170		}
1171	}
1172
1173	acpi_video_device_bind(video, data);
1174	acpi_video_device_find_cap(data);
1175
1176	mutex_lock(&video->device_list_lock);
1177	list_add_tail(&data->entry, &video->video_device_list);
1178	mutex_unlock(&video->device_list_lock);
1179
1180	return status;
1181}
1182
1183/*
1184 *  Arg:
1185 *	video	: video bus device
1186 *
1187 *  Return:
1188 *	none
1189 *
1190 *  Enumerate the video device list of the video bus,
1191 *  bind the ids with the corresponding video devices
1192 *  under the video bus.
1193 */
1194
1195static void acpi_video_device_rebind(struct acpi_video_bus *video)
1196{
1197	struct acpi_video_device *dev;
1198
1199	mutex_lock(&video->device_list_lock);
1200
1201	list_for_each_entry(dev, &video->video_device_list, entry)
1202		acpi_video_device_bind(video, dev);
1203
1204	mutex_unlock(&video->device_list_lock);
1205}
1206
1207/*
1208 *  Arg:
1209 *	video	: video bus device
1210 *	device	: video output device under the video
1211 *		bus
1212 *
1213 *  Return:
1214 *	none
1215 *
1216 *  Bind the ids with the corresponding video devices
1217 *  under the video bus.
1218 */
1219
1220static void
1221acpi_video_device_bind(struct acpi_video_bus *video,
1222		       struct acpi_video_device *device)
1223{
1224	struct acpi_video_enumerated_device *ids;
1225	int i;
1226
1227	for (i = 0; i < video->attached_count; i++) {
1228		ids = &video->attached_array[i];
1229		if (device->device_id == (ids->value.int_val & 0xffff)) {
1230			ids->bind_info = device;
1231			ACPI_DEBUG_PRINT((ACPI_DB_INFO, "device_bind %d\n", i));
1232		}
1233	}
1234}
1235
1236static bool acpi_video_device_in_dod(struct acpi_video_device *device)
1237{
1238	struct acpi_video_bus *video = device->video;
1239	int i;
1240
1241	/*
1242	 * If we have a broken _DOD or we have more than 8 output devices
1243	 * under the graphics controller node that we can't proper deal with
1244	 * in the operation region code currently, no need to test.
1245	 */
1246	if (!video->attached_count || video->child_count > 8)
1247		return true;
1248
1249	for (i = 0; i < video->attached_count; i++) {
1250		if ((video->attached_array[i].value.int_val & 0xfff) ==
1251		    (device->device_id & 0xfff))
1252			return true;
1253	}
1254
1255	return false;
1256}
1257
1258/*
1259 *  Arg:
1260 *	video	: video bus device
1261 *
1262 *  Return:
1263 *	< 0	: error
1264 *
1265 *  Call _DOD to enumerate all devices attached to display adapter
1266 *
1267 */
1268
1269static int acpi_video_device_enumerate(struct acpi_video_bus *video)
1270{
1271	int status;
1272	int count;
1273	int i;
1274	struct acpi_video_enumerated_device *active_list;
1275	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
1276	union acpi_object *dod = NULL;
1277	union acpi_object *obj;
1278
1279	status = acpi_evaluate_object(video->device->handle, "_DOD", NULL, &buffer);
1280	if (!ACPI_SUCCESS(status)) {
1281		ACPI_EXCEPTION((AE_INFO, status, "Evaluating _DOD"));
1282		return status;
1283	}
1284
1285	dod = buffer.pointer;
1286	if (!dod || (dod->type != ACPI_TYPE_PACKAGE)) {
1287		ACPI_EXCEPTION((AE_INFO, status, "Invalid _DOD data"));
1288		status = -EFAULT;
1289		goto out;
1290	}
1291
1292	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d video heads in _DOD\n",
1293			  dod->package.count));
1294
1295	active_list = kcalloc(1 + dod->package.count,
1296			      sizeof(struct acpi_video_enumerated_device),
1297			      GFP_KERNEL);
1298	if (!active_list) {
1299		status = -ENOMEM;
1300		goto out;
1301	}
1302
1303	count = 0;
1304	for (i = 0; i < dod->package.count; i++) {
1305		obj = &dod->package.elements[i];
1306
1307		if (obj->type != ACPI_TYPE_INTEGER) {
1308			printk(KERN_ERR PREFIX
1309				"Invalid _DOD data in element %d\n", i);
1310			continue;
1311		}
1312
1313		active_list[count].value.int_val = obj->integer.value;
1314		active_list[count].bind_info = NULL;
1315		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "dod element[%d] = %d\n", i,
1316				  (int)obj->integer.value));
1317		count++;
1318	}
1319
1320	kfree(video->attached_array);
1321
1322	video->attached_array = active_list;
1323	video->attached_count = count;
1324
1325out:
1326	kfree(buffer.pointer);
1327	return status;
1328}
1329
1330static int
1331acpi_video_get_next_level(struct acpi_video_device *device,
1332			  u32 level_current, u32 event)
1333{
1334	int min, max, min_above, max_below, i, l, delta = 255;
1335	max = max_below = 0;
1336	min = min_above = 255;
1337	/* Find closest level to level_current */
1338	for (i = 2; i < device->brightness->count; i++) {
1339		l = device->brightness->levels[i];
1340		if (abs(l - level_current) < abs(delta)) {
1341			delta = l - level_current;
1342			if (!delta)
1343				break;
1344		}
1345	}
1346	/* Ajust level_current to closest available level */
1347	level_current += delta;
1348	for (i = 2; i < device->brightness->count; i++) {
1349		l = device->brightness->levels[i];
1350		if (l < min)
1351			min = l;
1352		if (l > max)
1353			max = l;
1354		if (l < min_above && l > level_current)
1355			min_above = l;
1356		if (l > max_below && l < level_current)
1357			max_below = l;
1358	}
1359
1360	switch (event) {
1361	case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:
1362		return (level_current < max) ? min_above : min;
1363	case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:
1364		return (level_current < max) ? min_above : max;
1365	case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:
1366		return (level_current > min) ? max_below : min;
1367	case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS:
1368	case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:
1369		return 0;
1370	default:
1371		return level_current;
1372	}
1373}
1374
1375static void
1376acpi_video_switch_brightness(struct work_struct *work)
1377{
1378	struct acpi_video_device *device = container_of(to_delayed_work(work),
1379			     struct acpi_video_device, switch_brightness_work);
1380	unsigned long long level_current, level_next;
1381	int event = device->switch_brightness_event;
1382	int result = -EINVAL;
1383
1384	/* no warning message if acpi_backlight=vendor or a quirk is used */
1385	if (!acpi_video_verify_backlight_support())
1386		return;
1387
1388	if (!device->brightness)
1389		goto out;
1390
1391	result = acpi_video_device_lcd_get_level_current(device,
1392							 &level_current,
1393							 false);
1394	if (result)
1395		goto out;
1396
1397	level_next = acpi_video_get_next_level(device, level_current, event);
1398
1399	result = acpi_video_device_lcd_set_level(device, level_next);
1400
1401	if (!result)
1402		backlight_force_update(device->backlight,
1403				       BACKLIGHT_UPDATE_HOTKEY);
1404
1405out:
1406	if (result)
1407		printk(KERN_ERR PREFIX "Failed to switch the brightness\n");
1408}
1409
1410int acpi_video_get_edid(struct acpi_device *device, int type, int device_id,
1411			void **edid)
1412{
1413	struct acpi_video_bus *video;
1414	struct acpi_video_device *video_device;
1415	union acpi_object *buffer = NULL;
1416	acpi_status status;
1417	int i, length;
1418
1419	if (!device || !acpi_driver_data(device))
1420		return -EINVAL;
1421
1422	video = acpi_driver_data(device);
1423
1424	for (i = 0; i < video->attached_count; i++) {
1425		video_device = video->attached_array[i].bind_info;
1426		length = 256;
1427
1428		if (!video_device)
1429			continue;
1430
1431		if (!video_device->cap._DDC)
1432			continue;
1433
1434		if (type) {
1435			switch (type) {
1436			case ACPI_VIDEO_DISPLAY_CRT:
1437				if (!video_device->flags.crt)
1438					continue;
1439				break;
1440			case ACPI_VIDEO_DISPLAY_TV:
1441				if (!video_device->flags.tvout)
1442					continue;
1443				break;
1444			case ACPI_VIDEO_DISPLAY_DVI:
1445				if (!video_device->flags.dvi)
1446					continue;
1447				break;
1448			case ACPI_VIDEO_DISPLAY_LCD:
1449				if (!video_device->flags.lcd)
1450					continue;
1451				break;
1452			}
1453		} else if (video_device->device_id != device_id) {
1454			continue;
1455		}
1456
1457		status = acpi_video_device_EDID(video_device, &buffer, length);
1458
1459		if (ACPI_FAILURE(status) || !buffer ||
1460		    buffer->type != ACPI_TYPE_BUFFER) {
1461			length = 128;
1462			status = acpi_video_device_EDID(video_device, &buffer,
1463							length);
1464			if (ACPI_FAILURE(status) || !buffer ||
1465			    buffer->type != ACPI_TYPE_BUFFER) {
1466				continue;
1467			}
1468		}
1469
1470		*edid = buffer->buffer.pointer;
1471		return length;
1472	}
1473
1474	return -ENODEV;
1475}
1476EXPORT_SYMBOL(acpi_video_get_edid);
1477
1478static int
1479acpi_video_bus_get_devices(struct acpi_video_bus *video,
1480			   struct acpi_device *device)
1481{
1482	int status = 0;
1483	struct acpi_device *dev;
1484
1485	/*
1486	 * There are systems where video module known to work fine regardless
1487	 * of broken _DOD and ignoring returned value here doesn't cause
1488	 * any issues later.
1489	 */
1490	acpi_video_device_enumerate(video);
1491
1492	list_for_each_entry(dev, &device->children, node) {
1493
1494		status = acpi_video_bus_get_one_device(dev, video);
1495		if (status) {
1496			dev_err(&dev->dev, "Can't attach device\n");
1497			break;
1498		}
1499		video->child_count++;
1500	}
1501	return status;
1502}
1503
1504/* acpi_video interface */
1505
1506/*
1507 * Win8 requires setting bit2 of _DOS to let firmware know it shouldn't
1508 * preform any automatic brightness change on receiving a notification.
1509 */
1510static int acpi_video_bus_start_devices(struct acpi_video_bus *video)
1511{
1512	return acpi_video_bus_DOS(video, 0,
1513				  acpi_osi_is_win8() ? 1 : 0);
1514}
1515
1516static int acpi_video_bus_stop_devices(struct acpi_video_bus *video)
1517{
1518	return acpi_video_bus_DOS(video, 0,
1519				  acpi_osi_is_win8() ? 0 : 1);
1520}
1521
1522static void acpi_video_bus_notify(struct acpi_device *device, u32 event)
1523{
1524	struct acpi_video_bus *video = acpi_driver_data(device);
1525	struct input_dev *input;
1526	int keycode = 0;
1527
1528	if (!video || !video->input)
1529		return;
1530
1531	input = video->input;
1532
1533	switch (event) {
1534	case ACPI_VIDEO_NOTIFY_SWITCH:	/* User requested a switch,
1535					 * most likely via hotkey. */
1536		keycode = KEY_SWITCHVIDEOMODE;
1537		break;
1538
1539	case ACPI_VIDEO_NOTIFY_PROBE:	/* User plugged in or removed a video
1540					 * connector. */
1541		acpi_video_device_enumerate(video);
1542		acpi_video_device_rebind(video);
1543		keycode = KEY_SWITCHVIDEOMODE;
1544		break;
1545
1546	case ACPI_VIDEO_NOTIFY_CYCLE:	/* Cycle Display output hotkey pressed. */
1547		keycode = KEY_SWITCHVIDEOMODE;
1548		break;
1549	case ACPI_VIDEO_NOTIFY_NEXT_OUTPUT:	/* Next Display output hotkey pressed. */
1550		keycode = KEY_VIDEO_NEXT;
1551		break;
1552	case ACPI_VIDEO_NOTIFY_PREV_OUTPUT:	/* previous Display output hotkey pressed. */
1553		keycode = KEY_VIDEO_PREV;
1554		break;
1555
1556	default:
1557		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
1558				  "Unsupported event [0x%x]\n", event));
1559		break;
1560	}
1561
1562	if (acpi_notifier_call_chain(device, event, 0))
1563		/* Something vetoed the keypress. */
1564		keycode = 0;
1565
1566	if (keycode) {
1567		input_report_key(input, keycode, 1);
1568		input_sync(input);
1569		input_report_key(input, keycode, 0);
1570		input_sync(input);
1571	}
1572
1573	return;
1574}
1575
1576static void brightness_switch_event(struct acpi_video_device *video_device,
1577				    u32 event)
1578{
1579	if (!brightness_switch_enabled)
1580		return;
1581
1582	video_device->switch_brightness_event = event;
1583	schedule_delayed_work(&video_device->switch_brightness_work, HZ / 10);
1584}
1585
1586static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data)
1587{
1588	struct acpi_video_device *video_device = data;
1589	struct acpi_device *device = NULL;
1590	struct acpi_video_bus *bus;
1591	struct input_dev *input;
1592	int keycode = 0;
1593
1594	if (!video_device)
1595		return;
1596
1597	device = video_device->dev;
1598	bus = video_device->video;
1599	input = bus->input;
1600
1601	switch (event) {
1602	case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:	/* Cycle brightness */
1603		brightness_switch_event(video_device, event);
1604		keycode = KEY_BRIGHTNESS_CYCLE;
1605		break;
1606	case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:	/* Increase brightness */
1607		brightness_switch_event(video_device, event);
1608		keycode = KEY_BRIGHTNESSUP;
1609		break;
1610	case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:	/* Decrease brightness */
1611		brightness_switch_event(video_device, event);
1612		keycode = KEY_BRIGHTNESSDOWN;
1613		break;
1614	case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS:	/* zero brightness */
1615		brightness_switch_event(video_device, event);
1616		keycode = KEY_BRIGHTNESS_ZERO;
1617		break;
1618	case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:	/* display device off */
1619		brightness_switch_event(video_device, event);
1620		keycode = KEY_DISPLAY_OFF;
1621		break;
1622	default:
1623		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
1624				  "Unsupported event [0x%x]\n", event));
1625		break;
1626	}
1627
1628	acpi_notifier_call_chain(device, event, 0);
1629
1630	if (keycode) {
1631		input_report_key(input, keycode, 1);
1632		input_sync(input);
1633		input_report_key(input, keycode, 0);
1634		input_sync(input);
1635	}
1636
1637	return;
1638}
1639
1640static int acpi_video_resume(struct notifier_block *nb,
1641				unsigned long val, void *ign)
1642{
1643	struct acpi_video_bus *video;
1644	struct acpi_video_device *video_device;
1645	int i;
1646
1647	switch (val) {
1648	case PM_HIBERNATION_PREPARE:
1649	case PM_SUSPEND_PREPARE:
1650	case PM_RESTORE_PREPARE:
1651		return NOTIFY_DONE;
1652	}
1653
1654	video = container_of(nb, struct acpi_video_bus, pm_nb);
1655
1656	dev_info(&video->device->dev, "Restoring backlight state\n");
1657
1658	for (i = 0; i < video->attached_count; i++) {
1659		video_device = video->attached_array[i].bind_info;
1660		if (video_device && video_device->backlight)
1661			acpi_video_set_brightness(video_device->backlight);
1662	}
1663
1664	return NOTIFY_OK;
1665}
1666
1667static acpi_status
1668acpi_video_bus_match(acpi_handle handle, u32 level, void *context,
1669			void **return_value)
1670{
1671	struct acpi_device *device = context;
1672	struct acpi_device *sibling;
1673	int result;
1674
1675	if (handle == device->handle)
1676		return AE_CTRL_TERMINATE;
1677
1678	result = acpi_bus_get_device(handle, &sibling);
1679	if (result)
1680		return AE_OK;
1681
1682	if (!strcmp(acpi_device_name(sibling), ACPI_VIDEO_BUS_NAME))
1683			return AE_ALREADY_EXISTS;
1684
1685	return AE_OK;
1686}
1687
1688static void acpi_video_dev_register_backlight(struct acpi_video_device *device)
1689{
1690	struct backlight_properties props;
1691	struct pci_dev *pdev;
1692	acpi_handle acpi_parent;
1693	struct device *parent = NULL;
1694	int result;
1695	static int count;
1696	char *name;
1697
1698	/*
1699	 * Do not create backlight device for video output
1700	 * device that is not in the enumerated list.
1701	 */
1702	if (!acpi_video_device_in_dod(device)) {
1703		dev_dbg(&device->dev->dev, "not in _DOD list, ignore\n");
1704		return;
1705	}
1706
1707	result = acpi_video_init_brightness(device);
1708	if (result)
1709		return;
1710	name = kasprintf(GFP_KERNEL, "acpi_video%d", count);
1711	if (!name)
1712		return;
1713	count++;
1714
1715	acpi_get_parent(device->dev->handle, &acpi_parent);
1716
1717	pdev = acpi_get_pci_dev(acpi_parent);
1718	if (pdev) {
1719		parent = &pdev->dev;
1720		pci_dev_put(pdev);
1721	}
1722
1723	memset(&props, 0, sizeof(struct backlight_properties));
1724	props.type = BACKLIGHT_FIRMWARE;
1725	props.max_brightness = device->brightness->count - 3;
1726	device->backlight = backlight_device_register(name,
1727						      parent,
1728						      device,
1729						      &acpi_backlight_ops,
1730						      &props);
1731	kfree(name);
1732	if (IS_ERR(device->backlight))
1733		return;
1734
1735	/*
1736	 * Save current brightness level in case we have to restore it
1737	 * before acpi_video_device_lcd_set_level() is called next time.
1738	 */
1739	device->backlight->props.brightness =
1740			acpi_video_get_brightness(device->backlight);
1741
1742	device->cooling_dev = thermal_cooling_device_register("LCD",
1743				device->dev, &video_cooling_ops);
1744	if (IS_ERR(device->cooling_dev)) {
1745		/*
1746		 * Set cooling_dev to NULL so we don't crash trying to free it.
1747		 * Also, why the hell we are returning early and not attempt to
1748		 * register video output if cooling device registration failed?
1749		 * -- dtor
1750		 */
1751		device->cooling_dev = NULL;
1752		return;
1753	}
1754
1755	dev_info(&device->dev->dev, "registered as cooling_device%d\n",
1756		 device->cooling_dev->id);
1757	result = sysfs_create_link(&device->dev->dev.kobj,
1758			&device->cooling_dev->device.kobj,
1759			"thermal_cooling");
1760	if (result)
1761		printk(KERN_ERR PREFIX "Create sysfs link\n");
1762	result = sysfs_create_link(&device->cooling_dev->device.kobj,
1763			&device->dev->dev.kobj, "device");
1764	if (result)
1765		printk(KERN_ERR PREFIX "Create sysfs link\n");
1766}
1767
1768static void acpi_video_run_bcl_for_osi(struct acpi_video_bus *video)
1769{
1770	struct acpi_video_device *dev;
1771	union acpi_object *levels;
1772
1773	mutex_lock(&video->device_list_lock);
1774	list_for_each_entry(dev, &video->video_device_list, entry) {
1775		if (!acpi_video_device_lcd_query_levels(dev, &levels))
1776			kfree(levels);
1777	}
1778	mutex_unlock(&video->device_list_lock);
1779}
1780
1781static int acpi_video_bus_register_backlight(struct acpi_video_bus *video)
1782{
1783	struct acpi_video_device *dev;
1784
1785	if (video->backlight_registered)
1786		return 0;
1787
1788	acpi_video_run_bcl_for_osi(video);
1789
1790	if (!acpi_video_verify_backlight_support())
1791		return 0;
1792
1793	mutex_lock(&video->device_list_lock);
1794	list_for_each_entry(dev, &video->video_device_list, entry)
1795		acpi_video_dev_register_backlight(dev);
1796	mutex_unlock(&video->device_list_lock);
1797
1798	video->backlight_registered = true;
1799
1800	video->pm_nb.notifier_call = acpi_video_resume;
1801	video->pm_nb.priority = 0;
1802	return register_pm_notifier(&video->pm_nb);
1803}
1804
1805static void acpi_video_dev_unregister_backlight(struct acpi_video_device *device)
1806{
1807	if (device->backlight) {
1808		backlight_device_unregister(device->backlight);
1809		device->backlight = NULL;
1810	}
1811	if (device->brightness) {
1812		kfree(device->brightness->levels);
1813		kfree(device->brightness);
1814		device->brightness = NULL;
1815	}
1816	if (device->cooling_dev) {
1817		sysfs_remove_link(&device->dev->dev.kobj, "thermal_cooling");
1818		sysfs_remove_link(&device->cooling_dev->device.kobj, "device");
1819		thermal_cooling_device_unregister(device->cooling_dev);
1820		device->cooling_dev = NULL;
1821	}
1822}
1823
1824static int acpi_video_bus_unregister_backlight(struct acpi_video_bus *video)
1825{
1826	struct acpi_video_device *dev;
1827	int error;
1828
1829	if (!video->backlight_registered)
1830		return 0;
1831
1832	error = unregister_pm_notifier(&video->pm_nb);
1833
1834	mutex_lock(&video->device_list_lock);
1835	list_for_each_entry(dev, &video->video_device_list, entry)
1836		acpi_video_dev_unregister_backlight(dev);
1837	mutex_unlock(&video->device_list_lock);
1838
1839	video->backlight_registered = false;
1840
1841	return error;
1842}
1843
1844static void acpi_video_dev_add_notify_handler(struct acpi_video_device *device)
1845{
1846	acpi_status status;
1847	struct acpi_device *adev = device->dev;
1848
1849	status = acpi_install_notify_handler(adev->handle, ACPI_DEVICE_NOTIFY,
1850					     acpi_video_device_notify, device);
1851	if (ACPI_FAILURE(status))
1852		dev_err(&adev->dev, "Error installing notify handler\n");
1853	else
1854		device->flags.notify = 1;
1855}
1856
1857static int acpi_video_bus_add_notify_handler(struct acpi_video_bus *video)
1858{
1859	struct input_dev *input;
1860	struct acpi_video_device *dev;
1861	int error;
1862
1863	video->input = input = input_allocate_device();
1864	if (!input) {
1865		error = -ENOMEM;
1866		goto out;
1867	}
1868
1869	error = acpi_video_bus_start_devices(video);
1870	if (error)
1871		goto err_free_input;
1872
1873	snprintf(video->phys, sizeof(video->phys),
1874			"%s/video/input0", acpi_device_hid(video->device));
1875
1876	input->name = acpi_device_name(video->device);
1877	input->phys = video->phys;
1878	input->id.bustype = BUS_HOST;
1879	input->id.product = 0x06;
1880	input->dev.parent = &video->device->dev;
1881	input->evbit[0] = BIT(EV_KEY);
1882	set_bit(KEY_SWITCHVIDEOMODE, input->keybit);
1883	set_bit(KEY_VIDEO_NEXT, input->keybit);
1884	set_bit(KEY_VIDEO_PREV, input->keybit);
1885	set_bit(KEY_BRIGHTNESS_CYCLE, input->keybit);
1886	set_bit(KEY_BRIGHTNESSUP, input->keybit);
1887	set_bit(KEY_BRIGHTNESSDOWN, input->keybit);
1888	set_bit(KEY_BRIGHTNESS_ZERO, input->keybit);
1889	set_bit(KEY_DISPLAY_OFF, input->keybit);
1890
1891	error = input_register_device(input);
1892	if (error)
1893		goto err_stop_dev;
1894
1895	mutex_lock(&video->device_list_lock);
1896	list_for_each_entry(dev, &video->video_device_list, entry)
1897		acpi_video_dev_add_notify_handler(dev);
1898	mutex_unlock(&video->device_list_lock);
1899
1900	return 0;
1901
1902err_stop_dev:
1903	acpi_video_bus_stop_devices(video);
1904err_free_input:
1905	input_free_device(input);
1906	video->input = NULL;
1907out:
1908	return error;
1909}
1910
1911static void acpi_video_dev_remove_notify_handler(struct acpi_video_device *dev)
1912{
1913	if (dev->flags.notify) {
1914		acpi_remove_notify_handler(dev->dev->handle, ACPI_DEVICE_NOTIFY,
1915					   acpi_video_device_notify);
1916		dev->flags.notify = 0;
1917	}
1918}
1919
1920static void acpi_video_bus_remove_notify_handler(struct acpi_video_bus *video)
1921{
1922	struct acpi_video_device *dev;
1923
1924	mutex_lock(&video->device_list_lock);
1925	list_for_each_entry(dev, &video->video_device_list, entry)
1926		acpi_video_dev_remove_notify_handler(dev);
1927	mutex_unlock(&video->device_list_lock);
1928
1929	acpi_video_bus_stop_devices(video);
1930	input_unregister_device(video->input);
1931	video->input = NULL;
1932}
1933
1934static int acpi_video_backlight_notify(struct notifier_block *nb,
1935					unsigned long val, void *bd)
1936{
1937	struct backlight_device *backlight = bd;
1938	struct acpi_video_bus *video;
1939
1940	/* acpi_video_verify_backlight_support only cares about raw devices */
1941	if (backlight->props.type != BACKLIGHT_RAW)
1942		return NOTIFY_DONE;
1943
1944	video = container_of(nb, struct acpi_video_bus, backlight_nb);
1945
1946	switch (val) {
1947	case BACKLIGHT_REGISTERED:
1948		if (!acpi_video_verify_backlight_support())
1949			acpi_video_bus_unregister_backlight(video);
1950		break;
1951	case BACKLIGHT_UNREGISTERED:
1952		acpi_video_bus_register_backlight(video);
1953		break;
1954	}
1955
1956	return NOTIFY_OK;
1957}
1958
1959static int acpi_video_bus_add_backlight_notify_handler(
1960						struct acpi_video_bus *video)
1961{
1962	int error;
1963
1964	video->backlight_nb.notifier_call = acpi_video_backlight_notify;
1965	video->backlight_nb.priority = 0;
1966	error = backlight_register_notifier(&video->backlight_nb);
1967	if (error == 0)
1968		video->backlight_notifier_registered = true;
1969
1970	return error;
1971}
1972
1973static int acpi_video_bus_remove_backlight_notify_handler(
1974						struct acpi_video_bus *video)
1975{
1976	if (!video->backlight_notifier_registered)
1977		return 0;
1978
1979	video->backlight_notifier_registered = false;
1980
1981	return backlight_unregister_notifier(&video->backlight_nb);
1982}
1983
1984static int acpi_video_bus_put_devices(struct acpi_video_bus *video)
1985{
1986	struct acpi_video_device *dev, *next;
1987
1988	mutex_lock(&video->device_list_lock);
1989	list_for_each_entry_safe(dev, next, &video->video_device_list, entry) {
1990		list_del(&dev->entry);
1991		kfree(dev);
1992	}
1993	mutex_unlock(&video->device_list_lock);
1994
1995	return 0;
1996}
1997
1998static int instance;
1999
2000static int acpi_video_bus_add(struct acpi_device *device)
2001{
2002	struct acpi_video_bus *video;
2003	int error;
2004	acpi_status status;
2005
2006	status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
2007				device->parent->handle, 1,
2008				acpi_video_bus_match, NULL,
2009				device, NULL);
2010	if (status == AE_ALREADY_EXISTS) {
2011		printk(KERN_WARNING FW_BUG
2012			"Duplicate ACPI video bus devices for the"
2013			" same VGA controller, please try module "
2014			"parameter \"video.allow_duplicates=1\""
2015			"if the current driver doesn't work.\n");
2016		if (!allow_duplicates)
2017			return -ENODEV;
2018	}
2019
2020	video = kzalloc(sizeof(struct acpi_video_bus), GFP_KERNEL);
2021	if (!video)
2022		return -ENOMEM;
2023
2024	/* a hack to fix the duplicate name "VID" problem on T61 */
2025	if (!strcmp(device->pnp.bus_id, "VID")) {
2026		if (instance)
2027			device->pnp.bus_id[3] = '0' + instance;
2028		instance++;
2029	}
2030	/* a hack to fix the duplicate name "VGA" problem on Pa 3553 */
2031	if (!strcmp(device->pnp.bus_id, "VGA")) {
2032		if (instance)
2033			device->pnp.bus_id[3] = '0' + instance;
2034		instance++;
2035	}
2036
2037	video->device = device;
2038	strcpy(acpi_device_name(device), ACPI_VIDEO_BUS_NAME);
2039	strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);
2040	device->driver_data = video;
2041
2042	acpi_video_bus_find_cap(video);
2043	error = acpi_video_bus_check(video);
2044	if (error)
2045		goto err_free_video;
2046
2047	mutex_init(&video->device_list_lock);
2048	INIT_LIST_HEAD(&video->video_device_list);
2049
2050	error = acpi_video_bus_get_devices(video, device);
2051	if (error)
2052		goto err_put_video;
2053
2054	printk(KERN_INFO PREFIX "%s [%s] (multi-head: %s  rom: %s  post: %s)\n",
2055	       ACPI_VIDEO_DEVICE_NAME, acpi_device_bid(device),
2056	       video->flags.multihead ? "yes" : "no",
2057	       video->flags.rom ? "yes" : "no",
2058	       video->flags.post ? "yes" : "no");
2059	mutex_lock(&video_list_lock);
2060	list_add_tail(&video->entry, &video_bus_head);
2061	mutex_unlock(&video_list_lock);
2062
2063	acpi_video_bus_register_backlight(video);
2064	acpi_video_bus_add_notify_handler(video);
2065	acpi_video_bus_add_backlight_notify_handler(video);
2066
2067	return 0;
2068
2069err_put_video:
2070	acpi_video_bus_put_devices(video);
2071	kfree(video->attached_array);
2072err_free_video:
2073	kfree(video);
2074	device->driver_data = NULL;
2075
2076	return error;
2077}
2078
2079static int acpi_video_bus_remove(struct acpi_device *device)
2080{
2081	struct acpi_video_bus *video = NULL;
2082
2083
2084	if (!device || !acpi_driver_data(device))
2085		return -EINVAL;
2086
2087	video = acpi_driver_data(device);
2088
2089	acpi_video_bus_remove_backlight_notify_handler(video);
2090	acpi_video_bus_remove_notify_handler(video);
2091	acpi_video_bus_unregister_backlight(video);
2092	acpi_video_bus_put_devices(video);
2093
2094	mutex_lock(&video_list_lock);
2095	list_del(&video->entry);
2096	mutex_unlock(&video_list_lock);
2097
2098	kfree(video->attached_array);
2099	kfree(video);
2100
2101	return 0;
2102}
2103
2104static int __init is_i740(struct pci_dev *dev)
2105{
2106	if (dev->device == 0x00D1)
2107		return 1;
2108	if (dev->device == 0x7000)
2109		return 1;
2110	return 0;
2111}
2112
2113static int __init intel_opregion_present(void)
2114{
2115	int opregion = 0;
2116	struct pci_dev *dev = NULL;
2117	u32 address;
2118
2119	for_each_pci_dev(dev) {
2120		if ((dev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
2121			continue;
2122		if (dev->vendor != PCI_VENDOR_ID_INTEL)
2123			continue;
2124		/* We don't want to poke around undefined i740 registers */
2125		if (is_i740(dev))
2126			continue;
2127		pci_read_config_dword(dev, 0xfc, &address);
2128		if (!address)
2129			continue;
2130		opregion = 1;
2131	}
2132	return opregion;
2133}
2134
2135int acpi_video_register(void)
2136{
2137	int ret;
2138
2139	if (register_count) {
2140		/*
2141		 * if the function of acpi_video_register is already called,
2142		 * don't register the acpi_vide_bus again and return no error.
2143		 */
2144		return 0;
2145	}
2146
2147	mutex_init(&video_list_lock);
2148	INIT_LIST_HEAD(&video_bus_head);
2149
2150	ret = acpi_bus_register_driver(&acpi_video_bus);
2151	if (ret)
2152		return ret;
2153
2154	/*
2155	 * When the acpi_video_bus is loaded successfully, increase
2156	 * the counter reference.
2157	 */
2158	register_count = 1;
2159
2160	return 0;
2161}
2162EXPORT_SYMBOL(acpi_video_register);
2163
2164void acpi_video_unregister(void)
2165{
2166	if (!register_count) {
2167		/*
2168		 * If the acpi video bus is already unloaded, don't
2169		 * unload it again and return directly.
2170		 */
2171		return;
2172	}
2173	acpi_bus_unregister_driver(&acpi_video_bus);
2174
2175	register_count = 0;
2176
2177	return;
2178}
2179EXPORT_SYMBOL(acpi_video_unregister);
2180
2181void acpi_video_unregister_backlight(void)
2182{
2183	struct acpi_video_bus *video;
2184
2185	if (!register_count)
2186		return;
2187
2188	mutex_lock(&video_list_lock);
2189	list_for_each_entry(video, &video_bus_head, entry)
2190		acpi_video_bus_unregister_backlight(video);
2191	mutex_unlock(&video_list_lock);
2192}
2193EXPORT_SYMBOL(acpi_video_unregister_backlight);
2194
2195/*
2196 * This is kind of nasty. Hardware using Intel chipsets may require
2197 * the video opregion code to be run first in order to initialise
2198 * state before any ACPI video calls are made. To handle this we defer
2199 * registration of the video class until the opregion code has run.
2200 */
2201
2202static int __init acpi_video_init(void)
2203{
2204	/*
2205	 * Let the module load even if ACPI is disabled (e.g. due to
2206	 * a broken BIOS) so that i915.ko can still be loaded on such
2207	 * old systems without an AcpiOpRegion.
2208	 *
2209	 * acpi_video_register() will report -ENODEV later as well due
2210	 * to acpi_disabled when i915.ko tries to register itself afterwards.
2211	 */
2212	if (acpi_disabled)
2213		return 0;
2214
2215	dmi_check_system(video_dmi_table);
2216
2217	if (intel_opregion_present())
2218		return 0;
2219
2220	return acpi_video_register();
2221}
2222
2223static void __exit acpi_video_exit(void)
2224{
2225	acpi_video_unregister();
2226
2227	return;
2228}
2229
2230module_init(acpi_video_init);
2231module_exit(acpi_video_exit);
2232