xref: /openbmc/linux/drivers/acpi/acpi_video.c (revision 7587eb18)
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  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
21  */
22 
23 #include <linux/kernel.h>
24 #include <linux/module.h>
25 #include <linux/init.h>
26 #include <linux/types.h>
27 #include <linux/list.h>
28 #include <linux/mutex.h>
29 #include <linux/input.h>
30 #include <linux/backlight.h>
31 #include <linux/thermal.h>
32 #include <linux/sort.h>
33 #include <linux/pci.h>
34 #include <linux/pci_ids.h>
35 #include <linux/slab.h>
36 #include <linux/dmi.h>
37 #include <linux/suspend.h>
38 #include <linux/acpi.h>
39 #include <acpi/video.h>
40 #include <asm/uaccess.h>
41 
42 #define PREFIX "ACPI: "
43 
44 #define ACPI_VIDEO_BUS_NAME		"Video Bus"
45 #define ACPI_VIDEO_DEVICE_NAME		"Video Device"
46 #define ACPI_VIDEO_NOTIFY_SWITCH	0x80
47 #define ACPI_VIDEO_NOTIFY_PROBE		0x81
48 #define ACPI_VIDEO_NOTIFY_CYCLE		0x82
49 #define ACPI_VIDEO_NOTIFY_NEXT_OUTPUT	0x83
50 #define ACPI_VIDEO_NOTIFY_PREV_OUTPUT	0x84
51 
52 #define ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS	0x85
53 #define	ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS	0x86
54 #define ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS	0x87
55 #define ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS	0x88
56 #define ACPI_VIDEO_NOTIFY_DISPLAY_OFF		0x89
57 
58 #define MAX_NAME_LEN	20
59 
60 #define _COMPONENT		ACPI_VIDEO_COMPONENT
61 ACPI_MODULE_NAME("video");
62 
63 MODULE_AUTHOR("Bruno Ducrot");
64 MODULE_DESCRIPTION("ACPI Video Driver");
65 MODULE_LICENSE("GPL");
66 
67 static bool brightness_switch_enabled = 1;
68 module_param(brightness_switch_enabled, bool, 0644);
69 
70 /*
71  * By default, we don't allow duplicate ACPI video bus devices
72  * under the same VGA controller
73  */
74 static bool allow_duplicates;
75 module_param(allow_duplicates, bool, 0644);
76 
77 static int disable_backlight_sysfs_if = -1;
78 module_param(disable_backlight_sysfs_if, int, 0444);
79 
80 #define REPORT_OUTPUT_KEY_EVENTS		0x01
81 #define REPORT_BRIGHTNESS_KEY_EVENTS		0x02
82 static int report_key_events = -1;
83 module_param(report_key_events, int, 0644);
84 MODULE_PARM_DESC(report_key_events,
85 	"0: none, 1: output changes, 2: brightness changes, 3: all");
86 
87 static bool device_id_scheme = false;
88 module_param(device_id_scheme, bool, 0444);
89 
90 static bool only_lcd = false;
91 module_param(only_lcd, bool, 0444);
92 
93 static int register_count;
94 static DEFINE_MUTEX(register_count_mutex);
95 static DEFINE_MUTEX(video_list_lock);
96 static LIST_HEAD(video_bus_head);
97 static int acpi_video_bus_add(struct acpi_device *device);
98 static int acpi_video_bus_remove(struct acpi_device *device);
99 static void acpi_video_bus_notify(struct acpi_device *device, u32 event);
100 void acpi_video_detect_exit(void);
101 
102 static const struct acpi_device_id video_device_ids[] = {
103 	{ACPI_VIDEO_HID, 0},
104 	{"", 0},
105 };
106 MODULE_DEVICE_TABLE(acpi, video_device_ids);
107 
108 static 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 
119 struct 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 
126 struct 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 
136 struct 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 
149 struct 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 
157 struct acpi_video_bus {
158 	struct acpi_device *device;
159 	bool backlight_registered;
160 	u8 dos_setting;
161 	struct acpi_video_enumerated_device *attached_array;
162 	u8 attached_count;
163 	u8 child_count;
164 	struct acpi_video_bus_cap cap;
165 	struct acpi_video_bus_flags flags;
166 	struct list_head video_device_list;
167 	struct mutex device_list_lock;	/* protects video_device_list */
168 	struct list_head entry;
169 	struct input_dev *input;
170 	char phys[32];	/* for input device */
171 	struct notifier_block pm_nb;
172 };
173 
174 struct acpi_video_device_flags {
175 	u8 crt:1;
176 	u8 lcd:1;
177 	u8 tvout:1;
178 	u8 dvi:1;
179 	u8 bios:1;
180 	u8 unknown:1;
181 	u8 notify:1;
182 	u8 reserved:1;
183 };
184 
185 struct acpi_video_device_cap {
186 	u8 _ADR:1;		/* Return the unique ID */
187 	u8 _BCL:1;		/* Query list of brightness control levels supported */
188 	u8 _BCM:1;		/* Set the brightness level */
189 	u8 _BQC:1;		/* Get current brightness level */
190 	u8 _BCQ:1;		/* Some buggy BIOS uses _BCQ instead of _BQC */
191 	u8 _DDC:1;		/* Return the EDID for this device */
192 };
193 
194 struct acpi_video_device {
195 	unsigned long device_id;
196 	struct acpi_video_device_flags flags;
197 	struct acpi_video_device_cap cap;
198 	struct list_head entry;
199 	struct delayed_work switch_brightness_work;
200 	int switch_brightness_event;
201 	struct acpi_video_bus *video;
202 	struct acpi_device *dev;
203 	struct acpi_video_device_brightness *brightness;
204 	struct backlight_device *backlight;
205 	struct thermal_cooling_device *cooling_dev;
206 };
207 
208 static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data);
209 static void acpi_video_device_rebind(struct acpi_video_bus *video);
210 static void acpi_video_device_bind(struct acpi_video_bus *video,
211 				   struct acpi_video_device *device);
212 static int acpi_video_device_enumerate(struct acpi_video_bus *video);
213 static int acpi_video_device_lcd_set_level(struct acpi_video_device *device,
214 			int level);
215 static int acpi_video_device_lcd_get_level_current(
216 			struct acpi_video_device *device,
217 			unsigned long long *level, bool raw);
218 static int acpi_video_get_next_level(struct acpi_video_device *device,
219 				     u32 level_current, u32 event);
220 static void acpi_video_switch_brightness(struct work_struct *work);
221 
222 /* backlight device sysfs support */
223 static int acpi_video_get_brightness(struct backlight_device *bd)
224 {
225 	unsigned long long cur_level;
226 	int i;
227 	struct acpi_video_device *vd = bl_get_data(bd);
228 
229 	if (acpi_video_device_lcd_get_level_current(vd, &cur_level, false))
230 		return -EINVAL;
231 	for (i = 2; i < vd->brightness->count; i++) {
232 		if (vd->brightness->levels[i] == cur_level)
233 			/*
234 			 * The first two entries are special - see page 575
235 			 * of the ACPI spec 3.0
236 			 */
237 			return i - 2;
238 	}
239 	return 0;
240 }
241 
242 static int acpi_video_set_brightness(struct backlight_device *bd)
243 {
244 	int request_level = bd->props.brightness + 2;
245 	struct acpi_video_device *vd = bl_get_data(bd);
246 
247 	cancel_delayed_work(&vd->switch_brightness_work);
248 	return acpi_video_device_lcd_set_level(vd,
249 				vd->brightness->levels[request_level]);
250 }
251 
252 static const struct backlight_ops acpi_backlight_ops = {
253 	.get_brightness = acpi_video_get_brightness,
254 	.update_status  = acpi_video_set_brightness,
255 };
256 
257 /* thermal cooling device callbacks */
258 static int video_get_max_state(struct thermal_cooling_device *cooling_dev, unsigned
259 			       long *state)
260 {
261 	struct acpi_device *device = cooling_dev->devdata;
262 	struct acpi_video_device *video = acpi_driver_data(device);
263 
264 	*state = video->brightness->count - 3;
265 	return 0;
266 }
267 
268 static int video_get_cur_state(struct thermal_cooling_device *cooling_dev, unsigned
269 			       long *state)
270 {
271 	struct acpi_device *device = cooling_dev->devdata;
272 	struct acpi_video_device *video = acpi_driver_data(device);
273 	unsigned long long level;
274 	int offset;
275 
276 	if (acpi_video_device_lcd_get_level_current(video, &level, false))
277 		return -EINVAL;
278 	for (offset = 2; offset < video->brightness->count; offset++)
279 		if (level == video->brightness->levels[offset]) {
280 			*state = video->brightness->count - offset - 1;
281 			return 0;
282 		}
283 
284 	return -EINVAL;
285 }
286 
287 static int
288 video_set_cur_state(struct thermal_cooling_device *cooling_dev, unsigned long state)
289 {
290 	struct acpi_device *device = cooling_dev->devdata;
291 	struct acpi_video_device *video = acpi_driver_data(device);
292 	int level;
293 
294 	if (state >= video->brightness->count - 2)
295 		return -EINVAL;
296 
297 	state = video->brightness->count - state;
298 	level = video->brightness->levels[state - 1];
299 	return acpi_video_device_lcd_set_level(video, level);
300 }
301 
302 static const struct thermal_cooling_device_ops video_cooling_ops = {
303 	.get_max_state = video_get_max_state,
304 	.get_cur_state = video_get_cur_state,
305 	.set_cur_state = video_set_cur_state,
306 };
307 
308 /*
309  * --------------------------------------------------------------------------
310  *                             Video Management
311  * --------------------------------------------------------------------------
312  */
313 
314 static int
315 acpi_video_device_lcd_query_levels(acpi_handle handle,
316 				   union acpi_object **levels)
317 {
318 	int status;
319 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
320 	union acpi_object *obj;
321 
322 
323 	*levels = NULL;
324 
325 	status = acpi_evaluate_object(handle, "_BCL", NULL, &buffer);
326 	if (!ACPI_SUCCESS(status))
327 		return status;
328 	obj = (union acpi_object *)buffer.pointer;
329 	if (!obj || (obj->type != ACPI_TYPE_PACKAGE)) {
330 		printk(KERN_ERR PREFIX "Invalid _BCL data\n");
331 		status = -EFAULT;
332 		goto err;
333 	}
334 
335 	*levels = obj;
336 
337 	return 0;
338 
339 err:
340 	kfree(buffer.pointer);
341 
342 	return status;
343 }
344 
345 static int
346 acpi_video_device_lcd_set_level(struct acpi_video_device *device, int level)
347 {
348 	int status;
349 	int state;
350 
351 	status = acpi_execute_simple_method(device->dev->handle,
352 					    "_BCM", level);
353 	if (ACPI_FAILURE(status)) {
354 		ACPI_ERROR((AE_INFO, "Evaluating _BCM failed"));
355 		return -EIO;
356 	}
357 
358 	device->brightness->curr = level;
359 	for (state = 2; state < device->brightness->count; state++)
360 		if (level == device->brightness->levels[state]) {
361 			if (device->backlight)
362 				device->backlight->props.brightness = state - 2;
363 			return 0;
364 		}
365 
366 	ACPI_ERROR((AE_INFO, "Current brightness invalid"));
367 	return -EINVAL;
368 }
369 
370 /*
371  * For some buggy _BQC methods, we need to add a constant value to
372  * the _BQC return value to get the actual current brightness level
373  */
374 
375 static int bqc_offset_aml_bug_workaround;
376 static int video_set_bqc_offset(const struct dmi_system_id *d)
377 {
378 	bqc_offset_aml_bug_workaround = 9;
379 	return 0;
380 }
381 
382 static int video_disable_backlight_sysfs_if(
383 	const struct dmi_system_id *d)
384 {
385 	if (disable_backlight_sysfs_if == -1)
386 		disable_backlight_sysfs_if = 1;
387 	return 0;
388 }
389 
390 static int video_set_device_id_scheme(const struct dmi_system_id *d)
391 {
392 	device_id_scheme = true;
393 	return 0;
394 }
395 
396 static int video_enable_only_lcd(const struct dmi_system_id *d)
397 {
398 	only_lcd = true;
399 	return 0;
400 }
401 
402 static int video_set_report_key_events(const struct dmi_system_id *id)
403 {
404 	if (report_key_events == -1)
405 		report_key_events = (uintptr_t)id->driver_data;
406 	return 0;
407 }
408 
409 static struct dmi_system_id video_dmi_table[] = {
410 	/*
411 	 * Broken _BQC workaround http://bugzilla.kernel.org/show_bug.cgi?id=13121
412 	 */
413 	{
414 	 .callback = video_set_bqc_offset,
415 	 .ident = "Acer Aspire 5720",
416 	 .matches = {
417 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
418 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5720"),
419 		},
420 	},
421 	{
422 	 .callback = video_set_bqc_offset,
423 	 .ident = "Acer Aspire 5710Z",
424 	 .matches = {
425 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
426 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5710Z"),
427 		},
428 	},
429 	{
430 	 .callback = video_set_bqc_offset,
431 	 .ident = "eMachines E510",
432 	 .matches = {
433 		DMI_MATCH(DMI_BOARD_VENDOR, "EMACHINES"),
434 		DMI_MATCH(DMI_PRODUCT_NAME, "eMachines E510"),
435 		},
436 	},
437 	{
438 	 .callback = video_set_bqc_offset,
439 	 .ident = "Acer Aspire 5315",
440 	 .matches = {
441 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
442 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5315"),
443 		},
444 	},
445 	{
446 	 .callback = video_set_bqc_offset,
447 	 .ident = "Acer Aspire 7720",
448 	 .matches = {
449 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
450 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 7720"),
451 		},
452 	},
453 
454 	/*
455 	 * Some machines have a broken acpi-video interface for brightness
456 	 * control, but still need an acpi_video_device_lcd_set_level() call
457 	 * on resume to turn the backlight power on.  We Enable backlight
458 	 * control on these systems, but do not register a backlight sysfs
459 	 * as brightness control does not work.
460 	 */
461 	{
462 	 /* https://bugzilla.kernel.org/show_bug.cgi?id=21012 */
463 	 .callback = video_disable_backlight_sysfs_if,
464 	 .ident = "Toshiba Portege R700",
465 	 .matches = {
466 		DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
467 		DMI_MATCH(DMI_PRODUCT_NAME, "PORTEGE R700"),
468 		},
469 	},
470 	{
471 	 /* https://bugs.freedesktop.org/show_bug.cgi?id=82634 */
472 	 .callback = video_disable_backlight_sysfs_if,
473 	 .ident = "Toshiba Portege R830",
474 	 .matches = {
475 		DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
476 		DMI_MATCH(DMI_PRODUCT_NAME, "PORTEGE R830"),
477 		},
478 	},
479 	{
480 	 /* https://bugzilla.kernel.org/show_bug.cgi?id=21012 */
481 	 .callback = video_disable_backlight_sysfs_if,
482 	 .ident = "Toshiba Satellite R830",
483 	 .matches = {
484 		DMI_MATCH(DMI_SYS_VENDOR, "TOSHIBA"),
485 		DMI_MATCH(DMI_PRODUCT_NAME, "SATELLITE R830"),
486 		},
487 	},
488 	/*
489 	 * Some machine's _DOD IDs don't have bit 31(Device ID Scheme) set
490 	 * but the IDs actually follow the Device ID Scheme.
491 	 */
492 	{
493 	 /* https://bugzilla.kernel.org/show_bug.cgi?id=104121 */
494 	 .callback = video_set_device_id_scheme,
495 	 .ident = "ESPRIMO Mobile M9410",
496 	 .matches = {
497 		DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU SIEMENS"),
498 		DMI_MATCH(DMI_PRODUCT_NAME, "ESPRIMO Mobile M9410"),
499 		},
500 	},
501 	/*
502 	 * Some machines have multiple video output devices, but only the one
503 	 * that is the type of LCD can do the backlight control so we should not
504 	 * register backlight interface for other video output devices.
505 	 */
506 	{
507 	 /* https://bugzilla.kernel.org/show_bug.cgi?id=104121 */
508 	 .callback = video_enable_only_lcd,
509 	 .ident = "ESPRIMO Mobile M9410",
510 	 .matches = {
511 		DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU SIEMENS"),
512 		DMI_MATCH(DMI_PRODUCT_NAME, "ESPRIMO Mobile M9410"),
513 		},
514 	},
515 	/*
516 	 * Some machines report wrong key events on the acpi-bus, suppress
517 	 * key event reporting on these.  Note this is only intended to work
518 	 * around events which are plain wrong. In some cases we get double
519 	 * events, in this case acpi-video is considered the canonical source
520 	 * and the events from the other source should be filtered. E.g.
521 	 * by calling acpi_video_handles_brightness_key_presses() from the
522 	 * vendor acpi/wmi driver or by using /lib/udev/hwdb.d/60-keyboard.hwdb
523 	 */
524 	{
525 	 .callback = video_set_report_key_events,
526 	 .driver_data = (void *)((uintptr_t)REPORT_OUTPUT_KEY_EVENTS),
527 	 .ident = "Dell Vostro V131",
528 	 .matches = {
529 		DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
530 		DMI_MATCH(DMI_PRODUCT_NAME, "Vostro V131"),
531 		},
532 	},
533 	{}
534 };
535 
536 static unsigned long long
537 acpi_video_bqc_value_to_level(struct acpi_video_device *device,
538 			      unsigned long long bqc_value)
539 {
540 	unsigned long long level;
541 
542 	if (device->brightness->flags._BQC_use_index) {
543 		/*
544 		 * _BQC returns an index that doesn't account for
545 		 * the first 2 items with special meaning, so we need
546 		 * to compensate for that by offsetting ourselves
547 		 */
548 		if (device->brightness->flags._BCL_reversed)
549 			bqc_value = device->brightness->count - 3 - bqc_value;
550 
551 		level = device->brightness->levels[bqc_value + 2];
552 	} else {
553 		level = bqc_value;
554 	}
555 
556 	level += bqc_offset_aml_bug_workaround;
557 
558 	return level;
559 }
560 
561 static int
562 acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
563 					unsigned long long *level, bool raw)
564 {
565 	acpi_status status = AE_OK;
566 	int i;
567 
568 	if (device->cap._BQC || device->cap._BCQ) {
569 		char *buf = device->cap._BQC ? "_BQC" : "_BCQ";
570 
571 		status = acpi_evaluate_integer(device->dev->handle, buf,
572 						NULL, level);
573 		if (ACPI_SUCCESS(status)) {
574 			if (raw) {
575 				/*
576 				 * Caller has indicated he wants the raw
577 				 * value returned by _BQC, so don't furtherly
578 				 * mess with the value.
579 				 */
580 				return 0;
581 			}
582 
583 			*level = acpi_video_bqc_value_to_level(device, *level);
584 
585 			for (i = 2; i < device->brightness->count; i++)
586 				if (device->brightness->levels[i] == *level) {
587 					device->brightness->curr = *level;
588 					return 0;
589 				}
590 			/*
591 			 * BQC returned an invalid level.
592 			 * Stop using it.
593 			 */
594 			ACPI_WARNING((AE_INFO,
595 				      "%s returned an invalid level",
596 				      buf));
597 			device->cap._BQC = device->cap._BCQ = 0;
598 		} else {
599 			/*
600 			 * Fixme:
601 			 * should we return an error or ignore this failure?
602 			 * dev->brightness->curr is a cached value which stores
603 			 * the correct current backlight level in most cases.
604 			 * ACPI video backlight still works w/ buggy _BQC.
605 			 * http://bugzilla.kernel.org/show_bug.cgi?id=12233
606 			 */
607 			ACPI_WARNING((AE_INFO, "Evaluating %s failed", buf));
608 			device->cap._BQC = device->cap._BCQ = 0;
609 		}
610 	}
611 
612 	*level = device->brightness->curr;
613 	return 0;
614 }
615 
616 static int
617 acpi_video_device_EDID(struct acpi_video_device *device,
618 		       union acpi_object **edid, ssize_t length)
619 {
620 	int status;
621 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
622 	union acpi_object *obj;
623 	union acpi_object arg0 = { ACPI_TYPE_INTEGER };
624 	struct acpi_object_list args = { 1, &arg0 };
625 
626 
627 	*edid = NULL;
628 
629 	if (!device)
630 		return -ENODEV;
631 	if (length == 128)
632 		arg0.integer.value = 1;
633 	else if (length == 256)
634 		arg0.integer.value = 2;
635 	else
636 		return -EINVAL;
637 
638 	status = acpi_evaluate_object(device->dev->handle, "_DDC", &args, &buffer);
639 	if (ACPI_FAILURE(status))
640 		return -ENODEV;
641 
642 	obj = buffer.pointer;
643 
644 	if (obj && obj->type == ACPI_TYPE_BUFFER)
645 		*edid = obj;
646 	else {
647 		printk(KERN_ERR PREFIX "Invalid _DDC data\n");
648 		status = -EFAULT;
649 		kfree(obj);
650 	}
651 
652 	return status;
653 }
654 
655 /* bus */
656 
657 /*
658  *  Arg:
659  *	video		: video bus device pointer
660  *	bios_flag	:
661  *		0.	The system BIOS should NOT automatically switch(toggle)
662  *			the active display output.
663  *		1.	The system BIOS should automatically switch (toggle) the
664  *			active display output. No switch event.
665  *		2.	The _DGS value should be locked.
666  *		3.	The system BIOS should not automatically switch (toggle) the
667  *			active display output, but instead generate the display switch
668  *			event notify code.
669  *	lcd_flag	:
670  *		0.	The system BIOS should automatically control the brightness level
671  *			of the LCD when the power changes from AC to DC
672  *		1.	The system BIOS should NOT automatically control the brightness
673  *			level of the LCD when the power changes from AC to DC.
674  *  Return Value:
675  *		-EINVAL	wrong arg.
676  */
677 
678 static int
679 acpi_video_bus_DOS(struct acpi_video_bus *video, int bios_flag, int lcd_flag)
680 {
681 	acpi_status status;
682 
683 	if (!video->cap._DOS)
684 		return 0;
685 
686 	if (bios_flag < 0 || bios_flag > 3 || lcd_flag < 0 || lcd_flag > 1)
687 		return -EINVAL;
688 	video->dos_setting = (lcd_flag << 2) | bios_flag;
689 	status = acpi_execute_simple_method(video->device->handle, "_DOS",
690 					    (lcd_flag << 2) | bios_flag);
691 	if (ACPI_FAILURE(status))
692 		return -EIO;
693 
694 	return 0;
695 }
696 
697 /*
698  * Simple comparison function used to sort backlight levels.
699  */
700 
701 static int
702 acpi_video_cmp_level(const void *a, const void *b)
703 {
704 	return *(int *)a - *(int *)b;
705 }
706 
707 /*
708  * Decides if _BQC/_BCQ for this system is usable
709  *
710  * We do this by changing the level first and then read out the current
711  * brightness level, if the value does not match, find out if it is using
712  * index. If not, clear the _BQC/_BCQ capability.
713  */
714 static int acpi_video_bqc_quirk(struct acpi_video_device *device,
715 				int max_level, int current_level)
716 {
717 	struct acpi_video_device_brightness *br = device->brightness;
718 	int result;
719 	unsigned long long level;
720 	int test_level;
721 
722 	/* don't mess with existing known broken systems */
723 	if (bqc_offset_aml_bug_workaround)
724 		return 0;
725 
726 	/*
727 	 * Some systems always report current brightness level as maximum
728 	 * through _BQC, we need to test another value for them.
729 	 */
730 	test_level = current_level == max_level ? br->levels[3] : max_level;
731 
732 	result = acpi_video_device_lcd_set_level(device, test_level);
733 	if (result)
734 		return result;
735 
736 	result = acpi_video_device_lcd_get_level_current(device, &level, true);
737 	if (result)
738 		return result;
739 
740 	if (level != test_level) {
741 		/* buggy _BQC found, need to find out if it uses index */
742 		if (level < br->count) {
743 			if (br->flags._BCL_reversed)
744 				level = br->count - 3 - level;
745 			if (br->levels[level + 2] == test_level)
746 				br->flags._BQC_use_index = 1;
747 		}
748 
749 		if (!br->flags._BQC_use_index)
750 			device->cap._BQC = device->cap._BCQ = 0;
751 	}
752 
753 	return 0;
754 }
755 
756 int acpi_video_get_levels(struct acpi_device *device,
757 			  struct acpi_video_device_brightness **dev_br,
758 			  int *pmax_level)
759 {
760 	union acpi_object *obj = NULL;
761 	int i, max_level = 0, count = 0, level_ac_battery = 0;
762 	union acpi_object *o;
763 	struct acpi_video_device_brightness *br = NULL;
764 	int result = 0;
765 	u32 value;
766 
767 	if (!ACPI_SUCCESS(acpi_video_device_lcd_query_levels(device->handle,
768 								&obj))) {
769 		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Could not query available "
770 						"LCD brightness level\n"));
771 		result = -ENODEV;
772 		goto out;
773 	}
774 
775 	if (obj->package.count < 2) {
776 		result = -EINVAL;
777 		goto out;
778 	}
779 
780 	br = kzalloc(sizeof(*br), GFP_KERNEL);
781 	if (!br) {
782 		printk(KERN_ERR "can't allocate memory\n");
783 		result = -ENOMEM;
784 		goto out;
785 	}
786 
787 	br->levels = kmalloc((obj->package.count + 2) * sizeof *(br->levels),
788 				GFP_KERNEL);
789 	if (!br->levels) {
790 		result = -ENOMEM;
791 		goto out_free;
792 	}
793 
794 	for (i = 0; i < obj->package.count; i++) {
795 		o = (union acpi_object *)&obj->package.elements[i];
796 		if (o->type != ACPI_TYPE_INTEGER) {
797 			printk(KERN_ERR PREFIX "Invalid data\n");
798 			continue;
799 		}
800 		value = (u32) o->integer.value;
801 		/* Skip duplicate entries */
802 		if (count > 2 && br->levels[count - 1] == value)
803 			continue;
804 
805 		br->levels[count] = value;
806 
807 		if (br->levels[count] > max_level)
808 			max_level = br->levels[count];
809 		count++;
810 	}
811 
812 	/*
813 	 * some buggy BIOS don't export the levels
814 	 * when machine is on AC/Battery in _BCL package.
815 	 * In this case, the first two elements in _BCL packages
816 	 * are also supported brightness levels that OS should take care of.
817 	 */
818 	for (i = 2; i < count; i++) {
819 		if (br->levels[i] == br->levels[0])
820 			level_ac_battery++;
821 		if (br->levels[i] == br->levels[1])
822 			level_ac_battery++;
823 	}
824 
825 	if (level_ac_battery < 2) {
826 		level_ac_battery = 2 - level_ac_battery;
827 		br->flags._BCL_no_ac_battery_levels = 1;
828 		for (i = (count - 1 + level_ac_battery); i >= 2; i--)
829 			br->levels[i] = br->levels[i - level_ac_battery];
830 		count += level_ac_battery;
831 	} else if (level_ac_battery > 2)
832 		ACPI_ERROR((AE_INFO, "Too many duplicates in _BCL package"));
833 
834 	/* Check if the _BCL package is in a reversed order */
835 	if (max_level == br->levels[2]) {
836 		br->flags._BCL_reversed = 1;
837 		sort(&br->levels[2], count - 2, sizeof(br->levels[2]),
838 			acpi_video_cmp_level, NULL);
839 	} else if (max_level != br->levels[count - 1])
840 		ACPI_ERROR((AE_INFO,
841 			    "Found unordered _BCL package"));
842 
843 	br->count = count;
844 	*dev_br = br;
845 	if (pmax_level)
846 		*pmax_level = max_level;
847 
848 out:
849 	kfree(obj);
850 	return result;
851 out_free:
852 	kfree(br);
853 	goto out;
854 }
855 EXPORT_SYMBOL(acpi_video_get_levels);
856 
857 /*
858  *  Arg:
859  *	device	: video output device (LCD, CRT, ..)
860  *
861  *  Return Value:
862  *	Maximum brightness level
863  *
864  *  Allocate and initialize device->brightness.
865  */
866 
867 static int
868 acpi_video_init_brightness(struct acpi_video_device *device)
869 {
870 	int i, max_level = 0;
871 	unsigned long long level, level_old;
872 	struct acpi_video_device_brightness *br = NULL;
873 	int result = -EINVAL;
874 
875 	result = acpi_video_get_levels(device->dev, &br, &max_level);
876 	if (result)
877 		return result;
878 	device->brightness = br;
879 
880 	/* _BQC uses INDEX while _BCL uses VALUE in some laptops */
881 	br->curr = level = max_level;
882 
883 	if (!device->cap._BQC)
884 		goto set_level;
885 
886 	result = acpi_video_device_lcd_get_level_current(device,
887 							 &level_old, true);
888 	if (result)
889 		goto out_free_levels;
890 
891 	result = acpi_video_bqc_quirk(device, max_level, level_old);
892 	if (result)
893 		goto out_free_levels;
894 	/*
895 	 * cap._BQC may get cleared due to _BQC is found to be broken
896 	 * in acpi_video_bqc_quirk, so check again here.
897 	 */
898 	if (!device->cap._BQC)
899 		goto set_level;
900 
901 	level = acpi_video_bqc_value_to_level(device, level_old);
902 	/*
903 	 * On some buggy laptops, _BQC returns an uninitialized
904 	 * value when invoked for the first time, i.e.
905 	 * level_old is invalid (no matter whether it's a level
906 	 * or an index). Set the backlight to max_level in this case.
907 	 */
908 	for (i = 2; i < br->count; i++)
909 		if (level == br->levels[i])
910 			break;
911 	if (i == br->count || !level)
912 		level = max_level;
913 
914 set_level:
915 	result = acpi_video_device_lcd_set_level(device, level);
916 	if (result)
917 		goto out_free_levels;
918 
919 	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
920 			  "found %d brightness levels\n", br->count - 2));
921 	return 0;
922 
923 out_free_levels:
924 	kfree(br->levels);
925 	kfree(br);
926 	device->brightness = NULL;
927 	return result;
928 }
929 
930 /*
931  *  Arg:
932  *	device	: video output device (LCD, CRT, ..)
933  *
934  *  Return Value:
935  *	None
936  *
937  *  Find out all required AML methods defined under the output
938  *  device.
939  */
940 
941 static void acpi_video_device_find_cap(struct acpi_video_device *device)
942 {
943 	if (acpi_has_method(device->dev->handle, "_ADR"))
944 		device->cap._ADR = 1;
945 	if (acpi_has_method(device->dev->handle, "_BCL"))
946 		device->cap._BCL = 1;
947 	if (acpi_has_method(device->dev->handle, "_BCM"))
948 		device->cap._BCM = 1;
949 	if (acpi_has_method(device->dev->handle, "_BQC")) {
950 		device->cap._BQC = 1;
951 	} else if (acpi_has_method(device->dev->handle, "_BCQ")) {
952 		printk(KERN_WARNING FW_BUG "_BCQ is used instead of _BQC\n");
953 		device->cap._BCQ = 1;
954 	}
955 
956 	if (acpi_has_method(device->dev->handle, "_DDC"))
957 		device->cap._DDC = 1;
958 }
959 
960 /*
961  *  Arg:
962  *	device	: video output device (VGA)
963  *
964  *  Return Value:
965  *	None
966  *
967  *  Find out all required AML methods defined under the video bus device.
968  */
969 
970 static void acpi_video_bus_find_cap(struct acpi_video_bus *video)
971 {
972 	if (acpi_has_method(video->device->handle, "_DOS"))
973 		video->cap._DOS = 1;
974 	if (acpi_has_method(video->device->handle, "_DOD"))
975 		video->cap._DOD = 1;
976 	if (acpi_has_method(video->device->handle, "_ROM"))
977 		video->cap._ROM = 1;
978 	if (acpi_has_method(video->device->handle, "_GPD"))
979 		video->cap._GPD = 1;
980 	if (acpi_has_method(video->device->handle, "_SPD"))
981 		video->cap._SPD = 1;
982 	if (acpi_has_method(video->device->handle, "_VPO"))
983 		video->cap._VPO = 1;
984 }
985 
986 /*
987  * Check whether the video bus device has required AML method to
988  * support the desired features
989  */
990 
991 static int acpi_video_bus_check(struct acpi_video_bus *video)
992 {
993 	acpi_status status = -ENOENT;
994 	struct pci_dev *dev;
995 
996 	if (!video)
997 		return -EINVAL;
998 
999 	dev = acpi_get_pci_dev(video->device->handle);
1000 	if (!dev)
1001 		return -ENODEV;
1002 	pci_dev_put(dev);
1003 
1004 	/*
1005 	 * Since there is no HID, CID and so on for VGA driver, we have
1006 	 * to check well known required nodes.
1007 	 */
1008 
1009 	/* Does this device support video switching? */
1010 	if (video->cap._DOS || video->cap._DOD) {
1011 		if (!video->cap._DOS) {
1012 			printk(KERN_WARNING FW_BUG
1013 				"ACPI(%s) defines _DOD but not _DOS\n",
1014 				acpi_device_bid(video->device));
1015 		}
1016 		video->flags.multihead = 1;
1017 		status = 0;
1018 	}
1019 
1020 	/* Does this device support retrieving a video ROM? */
1021 	if (video->cap._ROM) {
1022 		video->flags.rom = 1;
1023 		status = 0;
1024 	}
1025 
1026 	/* Does this device support configuring which video device to POST? */
1027 	if (video->cap._GPD && video->cap._SPD && video->cap._VPO) {
1028 		video->flags.post = 1;
1029 		status = 0;
1030 	}
1031 
1032 	return status;
1033 }
1034 
1035 /*
1036  * --------------------------------------------------------------------------
1037  *                               Driver Interface
1038  * --------------------------------------------------------------------------
1039  */
1040 
1041 /* device interface */
1042 static struct acpi_video_device_attrib *
1043 acpi_video_get_device_attr(struct acpi_video_bus *video, unsigned long device_id)
1044 {
1045 	struct acpi_video_enumerated_device *ids;
1046 	int i;
1047 
1048 	for (i = 0; i < video->attached_count; i++) {
1049 		ids = &video->attached_array[i];
1050 		if ((ids->value.int_val & 0xffff) == device_id)
1051 			return &ids->value.attrib;
1052 	}
1053 
1054 	return NULL;
1055 }
1056 
1057 static int
1058 acpi_video_get_device_type(struct acpi_video_bus *video,
1059 			   unsigned long device_id)
1060 {
1061 	struct acpi_video_enumerated_device *ids;
1062 	int i;
1063 
1064 	for (i = 0; i < video->attached_count; i++) {
1065 		ids = &video->attached_array[i];
1066 		if ((ids->value.int_val & 0xffff) == device_id)
1067 			return ids->value.int_val;
1068 	}
1069 
1070 	return 0;
1071 }
1072 
1073 static int
1074 acpi_video_bus_get_one_device(struct acpi_device *device,
1075 			      struct acpi_video_bus *video)
1076 {
1077 	unsigned long long device_id;
1078 	int status, device_type;
1079 	struct acpi_video_device *data;
1080 	struct acpi_video_device_attrib *attribute;
1081 
1082 	status =
1083 	    acpi_evaluate_integer(device->handle, "_ADR", NULL, &device_id);
1084 	/* Some device omits _ADR, we skip them instead of fail */
1085 	if (ACPI_FAILURE(status))
1086 		return 0;
1087 
1088 	data = kzalloc(sizeof(struct acpi_video_device), GFP_KERNEL);
1089 	if (!data)
1090 		return -ENOMEM;
1091 
1092 	strcpy(acpi_device_name(device), ACPI_VIDEO_DEVICE_NAME);
1093 	strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);
1094 	device->driver_data = data;
1095 
1096 	data->device_id = device_id;
1097 	data->video = video;
1098 	data->dev = device;
1099 	INIT_DELAYED_WORK(&data->switch_brightness_work,
1100 			  acpi_video_switch_brightness);
1101 
1102 	attribute = acpi_video_get_device_attr(video, device_id);
1103 
1104 	if (attribute && (attribute->device_id_scheme || device_id_scheme)) {
1105 		switch (attribute->display_type) {
1106 		case ACPI_VIDEO_DISPLAY_CRT:
1107 			data->flags.crt = 1;
1108 			break;
1109 		case ACPI_VIDEO_DISPLAY_TV:
1110 			data->flags.tvout = 1;
1111 			break;
1112 		case ACPI_VIDEO_DISPLAY_DVI:
1113 			data->flags.dvi = 1;
1114 			break;
1115 		case ACPI_VIDEO_DISPLAY_LCD:
1116 			data->flags.lcd = 1;
1117 			break;
1118 		default:
1119 			data->flags.unknown = 1;
1120 			break;
1121 		}
1122 		if (attribute->bios_can_detect)
1123 			data->flags.bios = 1;
1124 	} else {
1125 		/* Check for legacy IDs */
1126 		device_type = acpi_video_get_device_type(video, device_id);
1127 		/* Ignore bits 16 and 18-20 */
1128 		switch (device_type & 0xffe2ffff) {
1129 		case ACPI_VIDEO_DISPLAY_LEGACY_MONITOR:
1130 			data->flags.crt = 1;
1131 			break;
1132 		case ACPI_VIDEO_DISPLAY_LEGACY_PANEL:
1133 			data->flags.lcd = 1;
1134 			break;
1135 		case ACPI_VIDEO_DISPLAY_LEGACY_TV:
1136 			data->flags.tvout = 1;
1137 			break;
1138 		default:
1139 			data->flags.unknown = 1;
1140 		}
1141 	}
1142 
1143 	acpi_video_device_bind(video, data);
1144 	acpi_video_device_find_cap(data);
1145 
1146 	mutex_lock(&video->device_list_lock);
1147 	list_add_tail(&data->entry, &video->video_device_list);
1148 	mutex_unlock(&video->device_list_lock);
1149 
1150 	return status;
1151 }
1152 
1153 /*
1154  *  Arg:
1155  *	video	: video bus device
1156  *
1157  *  Return:
1158  *	none
1159  *
1160  *  Enumerate the video device list of the video bus,
1161  *  bind the ids with the corresponding video devices
1162  *  under the video bus.
1163  */
1164 
1165 static void acpi_video_device_rebind(struct acpi_video_bus *video)
1166 {
1167 	struct acpi_video_device *dev;
1168 
1169 	mutex_lock(&video->device_list_lock);
1170 
1171 	list_for_each_entry(dev, &video->video_device_list, entry)
1172 		acpi_video_device_bind(video, dev);
1173 
1174 	mutex_unlock(&video->device_list_lock);
1175 }
1176 
1177 /*
1178  *  Arg:
1179  *	video	: video bus device
1180  *	device	: video output device under the video
1181  *		bus
1182  *
1183  *  Return:
1184  *	none
1185  *
1186  *  Bind the ids with the corresponding video devices
1187  *  under the video bus.
1188  */
1189 
1190 static void
1191 acpi_video_device_bind(struct acpi_video_bus *video,
1192 		       struct acpi_video_device *device)
1193 {
1194 	struct acpi_video_enumerated_device *ids;
1195 	int i;
1196 
1197 	for (i = 0; i < video->attached_count; i++) {
1198 		ids = &video->attached_array[i];
1199 		if (device->device_id == (ids->value.int_val & 0xffff)) {
1200 			ids->bind_info = device;
1201 			ACPI_DEBUG_PRINT((ACPI_DB_INFO, "device_bind %d\n", i));
1202 		}
1203 	}
1204 }
1205 
1206 static bool acpi_video_device_in_dod(struct acpi_video_device *device)
1207 {
1208 	struct acpi_video_bus *video = device->video;
1209 	int i;
1210 
1211 	/*
1212 	 * If we have a broken _DOD or we have more than 8 output devices
1213 	 * under the graphics controller node that we can't proper deal with
1214 	 * in the operation region code currently, no need to test.
1215 	 */
1216 	if (!video->attached_count || video->child_count > 8)
1217 		return true;
1218 
1219 	for (i = 0; i < video->attached_count; i++) {
1220 		if ((video->attached_array[i].value.int_val & 0xfff) ==
1221 		    (device->device_id & 0xfff))
1222 			return true;
1223 	}
1224 
1225 	return false;
1226 }
1227 
1228 /*
1229  *  Arg:
1230  *	video	: video bus device
1231  *
1232  *  Return:
1233  *	< 0	: error
1234  *
1235  *  Call _DOD to enumerate all devices attached to display adapter
1236  *
1237  */
1238 
1239 static int acpi_video_device_enumerate(struct acpi_video_bus *video)
1240 {
1241 	int status;
1242 	int count;
1243 	int i;
1244 	struct acpi_video_enumerated_device *active_list;
1245 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
1246 	union acpi_object *dod = NULL;
1247 	union acpi_object *obj;
1248 
1249 	status = acpi_evaluate_object(video->device->handle, "_DOD", NULL, &buffer);
1250 	if (!ACPI_SUCCESS(status)) {
1251 		ACPI_EXCEPTION((AE_INFO, status, "Evaluating _DOD"));
1252 		return status;
1253 	}
1254 
1255 	dod = buffer.pointer;
1256 	if (!dod || (dod->type != ACPI_TYPE_PACKAGE)) {
1257 		ACPI_EXCEPTION((AE_INFO, status, "Invalid _DOD data"));
1258 		status = -EFAULT;
1259 		goto out;
1260 	}
1261 
1262 	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d video heads in _DOD\n",
1263 			  dod->package.count));
1264 
1265 	active_list = kcalloc(1 + dod->package.count,
1266 			      sizeof(struct acpi_video_enumerated_device),
1267 			      GFP_KERNEL);
1268 	if (!active_list) {
1269 		status = -ENOMEM;
1270 		goto out;
1271 	}
1272 
1273 	count = 0;
1274 	for (i = 0; i < dod->package.count; i++) {
1275 		obj = &dod->package.elements[i];
1276 
1277 		if (obj->type != ACPI_TYPE_INTEGER) {
1278 			printk(KERN_ERR PREFIX
1279 				"Invalid _DOD data in element %d\n", i);
1280 			continue;
1281 		}
1282 
1283 		active_list[count].value.int_val = obj->integer.value;
1284 		active_list[count].bind_info = NULL;
1285 		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "dod element[%d] = %d\n", i,
1286 				  (int)obj->integer.value));
1287 		count++;
1288 	}
1289 
1290 	kfree(video->attached_array);
1291 
1292 	video->attached_array = active_list;
1293 	video->attached_count = count;
1294 
1295 out:
1296 	kfree(buffer.pointer);
1297 	return status;
1298 }
1299 
1300 static int
1301 acpi_video_get_next_level(struct acpi_video_device *device,
1302 			  u32 level_current, u32 event)
1303 {
1304 	int min, max, min_above, max_below, i, l, delta = 255;
1305 	max = max_below = 0;
1306 	min = min_above = 255;
1307 	/* Find closest level to level_current */
1308 	for (i = 2; i < device->brightness->count; i++) {
1309 		l = device->brightness->levels[i];
1310 		if (abs(l - level_current) < abs(delta)) {
1311 			delta = l - level_current;
1312 			if (!delta)
1313 				break;
1314 		}
1315 	}
1316 	/* Ajust level_current to closest available level */
1317 	level_current += delta;
1318 	for (i = 2; i < device->brightness->count; i++) {
1319 		l = device->brightness->levels[i];
1320 		if (l < min)
1321 			min = l;
1322 		if (l > max)
1323 			max = l;
1324 		if (l < min_above && l > level_current)
1325 			min_above = l;
1326 		if (l > max_below && l < level_current)
1327 			max_below = l;
1328 	}
1329 
1330 	switch (event) {
1331 	case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:
1332 		return (level_current < max) ? min_above : min;
1333 	case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:
1334 		return (level_current < max) ? min_above : max;
1335 	case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:
1336 		return (level_current > min) ? max_below : min;
1337 	case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS:
1338 	case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:
1339 		return 0;
1340 	default:
1341 		return level_current;
1342 	}
1343 }
1344 
1345 static void
1346 acpi_video_switch_brightness(struct work_struct *work)
1347 {
1348 	struct acpi_video_device *device = container_of(to_delayed_work(work),
1349 			     struct acpi_video_device, switch_brightness_work);
1350 	unsigned long long level_current, level_next;
1351 	int event = device->switch_brightness_event;
1352 	int result = -EINVAL;
1353 
1354 	/* no warning message if acpi_backlight=vendor or a quirk is used */
1355 	if (!device->backlight)
1356 		return;
1357 
1358 	if (!device->brightness)
1359 		goto out;
1360 
1361 	result = acpi_video_device_lcd_get_level_current(device,
1362 							 &level_current,
1363 							 false);
1364 	if (result)
1365 		goto out;
1366 
1367 	level_next = acpi_video_get_next_level(device, level_current, event);
1368 
1369 	result = acpi_video_device_lcd_set_level(device, level_next);
1370 
1371 	if (!result)
1372 		backlight_force_update(device->backlight,
1373 				       BACKLIGHT_UPDATE_HOTKEY);
1374 
1375 out:
1376 	if (result)
1377 		printk(KERN_ERR PREFIX "Failed to switch the brightness\n");
1378 }
1379 
1380 int acpi_video_get_edid(struct acpi_device *device, int type, int device_id,
1381 			void **edid)
1382 {
1383 	struct acpi_video_bus *video;
1384 	struct acpi_video_device *video_device;
1385 	union acpi_object *buffer = NULL;
1386 	acpi_status status;
1387 	int i, length;
1388 
1389 	if (!device || !acpi_driver_data(device))
1390 		return -EINVAL;
1391 
1392 	video = acpi_driver_data(device);
1393 
1394 	for (i = 0; i < video->attached_count; i++) {
1395 		video_device = video->attached_array[i].bind_info;
1396 		length = 256;
1397 
1398 		if (!video_device)
1399 			continue;
1400 
1401 		if (!video_device->cap._DDC)
1402 			continue;
1403 
1404 		if (type) {
1405 			switch (type) {
1406 			case ACPI_VIDEO_DISPLAY_CRT:
1407 				if (!video_device->flags.crt)
1408 					continue;
1409 				break;
1410 			case ACPI_VIDEO_DISPLAY_TV:
1411 				if (!video_device->flags.tvout)
1412 					continue;
1413 				break;
1414 			case ACPI_VIDEO_DISPLAY_DVI:
1415 				if (!video_device->flags.dvi)
1416 					continue;
1417 				break;
1418 			case ACPI_VIDEO_DISPLAY_LCD:
1419 				if (!video_device->flags.lcd)
1420 					continue;
1421 				break;
1422 			}
1423 		} else if (video_device->device_id != device_id) {
1424 			continue;
1425 		}
1426 
1427 		status = acpi_video_device_EDID(video_device, &buffer, length);
1428 
1429 		if (ACPI_FAILURE(status) || !buffer ||
1430 		    buffer->type != ACPI_TYPE_BUFFER) {
1431 			length = 128;
1432 			status = acpi_video_device_EDID(video_device, &buffer,
1433 							length);
1434 			if (ACPI_FAILURE(status) || !buffer ||
1435 			    buffer->type != ACPI_TYPE_BUFFER) {
1436 				continue;
1437 			}
1438 		}
1439 
1440 		*edid = buffer->buffer.pointer;
1441 		return length;
1442 	}
1443 
1444 	return -ENODEV;
1445 }
1446 EXPORT_SYMBOL(acpi_video_get_edid);
1447 
1448 static int
1449 acpi_video_bus_get_devices(struct acpi_video_bus *video,
1450 			   struct acpi_device *device)
1451 {
1452 	int status = 0;
1453 	struct acpi_device *dev;
1454 
1455 	/*
1456 	 * There are systems where video module known to work fine regardless
1457 	 * of broken _DOD and ignoring returned value here doesn't cause
1458 	 * any issues later.
1459 	 */
1460 	acpi_video_device_enumerate(video);
1461 
1462 	list_for_each_entry(dev, &device->children, node) {
1463 
1464 		status = acpi_video_bus_get_one_device(dev, video);
1465 		if (status) {
1466 			dev_err(&dev->dev, "Can't attach device\n");
1467 			break;
1468 		}
1469 		video->child_count++;
1470 	}
1471 	return status;
1472 }
1473 
1474 /* acpi_video interface */
1475 
1476 /*
1477  * Win8 requires setting bit2 of _DOS to let firmware know it shouldn't
1478  * preform any automatic brightness change on receiving a notification.
1479  */
1480 static int acpi_video_bus_start_devices(struct acpi_video_bus *video)
1481 {
1482 	return acpi_video_bus_DOS(video, 0,
1483 				  acpi_osi_is_win8() ? 1 : 0);
1484 }
1485 
1486 static int acpi_video_bus_stop_devices(struct acpi_video_bus *video)
1487 {
1488 	return acpi_video_bus_DOS(video, 0,
1489 				  acpi_osi_is_win8() ? 0 : 1);
1490 }
1491 
1492 static void acpi_video_bus_notify(struct acpi_device *device, u32 event)
1493 {
1494 	struct acpi_video_bus *video = acpi_driver_data(device);
1495 	struct input_dev *input;
1496 	int keycode = 0;
1497 
1498 	if (!video || !video->input)
1499 		return;
1500 
1501 	input = video->input;
1502 
1503 	switch (event) {
1504 	case ACPI_VIDEO_NOTIFY_SWITCH:	/* User requested a switch,
1505 					 * most likely via hotkey. */
1506 		keycode = KEY_SWITCHVIDEOMODE;
1507 		break;
1508 
1509 	case ACPI_VIDEO_NOTIFY_PROBE:	/* User plugged in or removed a video
1510 					 * connector. */
1511 		acpi_video_device_enumerate(video);
1512 		acpi_video_device_rebind(video);
1513 		keycode = KEY_SWITCHVIDEOMODE;
1514 		break;
1515 
1516 	case ACPI_VIDEO_NOTIFY_CYCLE:	/* Cycle Display output hotkey pressed. */
1517 		keycode = KEY_SWITCHVIDEOMODE;
1518 		break;
1519 	case ACPI_VIDEO_NOTIFY_NEXT_OUTPUT:	/* Next Display output hotkey pressed. */
1520 		keycode = KEY_VIDEO_NEXT;
1521 		break;
1522 	case ACPI_VIDEO_NOTIFY_PREV_OUTPUT:	/* previous Display output hotkey pressed. */
1523 		keycode = KEY_VIDEO_PREV;
1524 		break;
1525 
1526 	default:
1527 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
1528 				  "Unsupported event [0x%x]\n", event));
1529 		break;
1530 	}
1531 
1532 	if (acpi_notifier_call_chain(device, event, 0))
1533 		/* Something vetoed the keypress. */
1534 		keycode = 0;
1535 
1536 	if (keycode && (report_key_events & REPORT_OUTPUT_KEY_EVENTS)) {
1537 		input_report_key(input, keycode, 1);
1538 		input_sync(input);
1539 		input_report_key(input, keycode, 0);
1540 		input_sync(input);
1541 	}
1542 
1543 	return;
1544 }
1545 
1546 static void brightness_switch_event(struct acpi_video_device *video_device,
1547 				    u32 event)
1548 {
1549 	if (!brightness_switch_enabled)
1550 		return;
1551 
1552 	video_device->switch_brightness_event = event;
1553 	schedule_delayed_work(&video_device->switch_brightness_work, HZ / 10);
1554 }
1555 
1556 static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data)
1557 {
1558 	struct acpi_video_device *video_device = data;
1559 	struct acpi_device *device = NULL;
1560 	struct acpi_video_bus *bus;
1561 	struct input_dev *input;
1562 	int keycode = 0;
1563 
1564 	if (!video_device)
1565 		return;
1566 
1567 	device = video_device->dev;
1568 	bus = video_device->video;
1569 	input = bus->input;
1570 
1571 	switch (event) {
1572 	case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:	/* Cycle brightness */
1573 		brightness_switch_event(video_device, event);
1574 		keycode = KEY_BRIGHTNESS_CYCLE;
1575 		break;
1576 	case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:	/* Increase brightness */
1577 		brightness_switch_event(video_device, event);
1578 		keycode = KEY_BRIGHTNESSUP;
1579 		break;
1580 	case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:	/* Decrease brightness */
1581 		brightness_switch_event(video_device, event);
1582 		keycode = KEY_BRIGHTNESSDOWN;
1583 		break;
1584 	case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS:	/* zero brightness */
1585 		brightness_switch_event(video_device, event);
1586 		keycode = KEY_BRIGHTNESS_ZERO;
1587 		break;
1588 	case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:	/* display device off */
1589 		brightness_switch_event(video_device, event);
1590 		keycode = KEY_DISPLAY_OFF;
1591 		break;
1592 	default:
1593 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
1594 				  "Unsupported event [0x%x]\n", event));
1595 		break;
1596 	}
1597 
1598 	acpi_notifier_call_chain(device, event, 0);
1599 
1600 	if (keycode && (report_key_events & REPORT_BRIGHTNESS_KEY_EVENTS)) {
1601 		input_report_key(input, keycode, 1);
1602 		input_sync(input);
1603 		input_report_key(input, keycode, 0);
1604 		input_sync(input);
1605 	}
1606 
1607 	return;
1608 }
1609 
1610 static int acpi_video_resume(struct notifier_block *nb,
1611 				unsigned long val, void *ign)
1612 {
1613 	struct acpi_video_bus *video;
1614 	struct acpi_video_device *video_device;
1615 	int i;
1616 
1617 	switch (val) {
1618 	case PM_HIBERNATION_PREPARE:
1619 	case PM_SUSPEND_PREPARE:
1620 	case PM_RESTORE_PREPARE:
1621 		return NOTIFY_DONE;
1622 	}
1623 
1624 	video = container_of(nb, struct acpi_video_bus, pm_nb);
1625 
1626 	dev_info(&video->device->dev, "Restoring backlight state\n");
1627 
1628 	for (i = 0; i < video->attached_count; i++) {
1629 		video_device = video->attached_array[i].bind_info;
1630 		if (video_device && video_device->brightness)
1631 			acpi_video_device_lcd_set_level(video_device,
1632 					video_device->brightness->curr);
1633 	}
1634 
1635 	return NOTIFY_OK;
1636 }
1637 
1638 static acpi_status
1639 acpi_video_bus_match(acpi_handle handle, u32 level, void *context,
1640 			void **return_value)
1641 {
1642 	struct acpi_device *device = context;
1643 	struct acpi_device *sibling;
1644 	int result;
1645 
1646 	if (handle == device->handle)
1647 		return AE_CTRL_TERMINATE;
1648 
1649 	result = acpi_bus_get_device(handle, &sibling);
1650 	if (result)
1651 		return AE_OK;
1652 
1653 	if (!strcmp(acpi_device_name(sibling), ACPI_VIDEO_BUS_NAME))
1654 			return AE_ALREADY_EXISTS;
1655 
1656 	return AE_OK;
1657 }
1658 
1659 static void acpi_video_dev_register_backlight(struct acpi_video_device *device)
1660 {
1661 	struct backlight_properties props;
1662 	struct pci_dev *pdev;
1663 	acpi_handle acpi_parent;
1664 	struct device *parent = NULL;
1665 	int result;
1666 	static int count;
1667 	char *name;
1668 
1669 	result = acpi_video_init_brightness(device);
1670 	if (result)
1671 		return;
1672 
1673 	if (disable_backlight_sysfs_if > 0)
1674 		return;
1675 
1676 	name = kasprintf(GFP_KERNEL, "acpi_video%d", count);
1677 	if (!name)
1678 		return;
1679 	count++;
1680 
1681 	acpi_get_parent(device->dev->handle, &acpi_parent);
1682 
1683 	pdev = acpi_get_pci_dev(acpi_parent);
1684 	if (pdev) {
1685 		parent = &pdev->dev;
1686 		pci_dev_put(pdev);
1687 	}
1688 
1689 	memset(&props, 0, sizeof(struct backlight_properties));
1690 	props.type = BACKLIGHT_FIRMWARE;
1691 	props.max_brightness = device->brightness->count - 3;
1692 	device->backlight = backlight_device_register(name,
1693 						      parent,
1694 						      device,
1695 						      &acpi_backlight_ops,
1696 						      &props);
1697 	kfree(name);
1698 	if (IS_ERR(device->backlight)) {
1699 		device->backlight = NULL;
1700 		return;
1701 	}
1702 
1703 	/*
1704 	 * Save current brightness level in case we have to restore it
1705 	 * before acpi_video_device_lcd_set_level() is called next time.
1706 	 */
1707 	device->backlight->props.brightness =
1708 			acpi_video_get_brightness(device->backlight);
1709 
1710 	device->cooling_dev = thermal_cooling_device_register("LCD",
1711 				device->dev, &video_cooling_ops);
1712 	if (IS_ERR(device->cooling_dev)) {
1713 		/*
1714 		 * Set cooling_dev to NULL so we don't crash trying to free it.
1715 		 * Also, why the hell we are returning early and not attempt to
1716 		 * register video output if cooling device registration failed?
1717 		 * -- dtor
1718 		 */
1719 		device->cooling_dev = NULL;
1720 		return;
1721 	}
1722 
1723 	dev_info(&device->dev->dev, "registered as cooling_device%d\n",
1724 		 device->cooling_dev->id);
1725 	result = sysfs_create_link(&device->dev->dev.kobj,
1726 			&device->cooling_dev->device.kobj,
1727 			"thermal_cooling");
1728 	if (result)
1729 		printk(KERN_ERR PREFIX "Create sysfs link\n");
1730 	result = sysfs_create_link(&device->cooling_dev->device.kobj,
1731 			&device->dev->dev.kobj, "device");
1732 	if (result)
1733 		printk(KERN_ERR PREFIX "Create sysfs link\n");
1734 }
1735 
1736 static void acpi_video_run_bcl_for_osi(struct acpi_video_bus *video)
1737 {
1738 	struct acpi_video_device *dev;
1739 	union acpi_object *levels;
1740 
1741 	mutex_lock(&video->device_list_lock);
1742 	list_for_each_entry(dev, &video->video_device_list, entry) {
1743 		if (!acpi_video_device_lcd_query_levels(dev->dev->handle, &levels))
1744 			kfree(levels);
1745 	}
1746 	mutex_unlock(&video->device_list_lock);
1747 }
1748 
1749 static bool acpi_video_should_register_backlight(struct acpi_video_device *dev)
1750 {
1751 	/*
1752 	 * Do not create backlight device for video output
1753 	 * device that is not in the enumerated list.
1754 	 */
1755 	if (!acpi_video_device_in_dod(dev)) {
1756 		dev_dbg(&dev->dev->dev, "not in _DOD list, ignore\n");
1757 		return false;
1758 	}
1759 
1760 	if (only_lcd)
1761 		return dev->flags.lcd;
1762 	return true;
1763 }
1764 
1765 static int acpi_video_bus_register_backlight(struct acpi_video_bus *video)
1766 {
1767 	struct acpi_video_device *dev;
1768 
1769 	if (video->backlight_registered)
1770 		return 0;
1771 
1772 	acpi_video_run_bcl_for_osi(video);
1773 
1774 	if (acpi_video_get_backlight_type() != acpi_backlight_video)
1775 		return 0;
1776 
1777 	mutex_lock(&video->device_list_lock);
1778 	list_for_each_entry(dev, &video->video_device_list, entry) {
1779 		if (acpi_video_should_register_backlight(dev))
1780 			acpi_video_dev_register_backlight(dev);
1781 	}
1782 	mutex_unlock(&video->device_list_lock);
1783 
1784 	video->backlight_registered = true;
1785 
1786 	video->pm_nb.notifier_call = acpi_video_resume;
1787 	video->pm_nb.priority = 0;
1788 	return register_pm_notifier(&video->pm_nb);
1789 }
1790 
1791 static void acpi_video_dev_unregister_backlight(struct acpi_video_device *device)
1792 {
1793 	if (device->backlight) {
1794 		backlight_device_unregister(device->backlight);
1795 		device->backlight = NULL;
1796 	}
1797 	if (device->brightness) {
1798 		kfree(device->brightness->levels);
1799 		kfree(device->brightness);
1800 		device->brightness = NULL;
1801 	}
1802 	if (device->cooling_dev) {
1803 		sysfs_remove_link(&device->dev->dev.kobj, "thermal_cooling");
1804 		sysfs_remove_link(&device->cooling_dev->device.kobj, "device");
1805 		thermal_cooling_device_unregister(device->cooling_dev);
1806 		device->cooling_dev = NULL;
1807 	}
1808 }
1809 
1810 static int acpi_video_bus_unregister_backlight(struct acpi_video_bus *video)
1811 {
1812 	struct acpi_video_device *dev;
1813 	int error;
1814 
1815 	if (!video->backlight_registered)
1816 		return 0;
1817 
1818 	error = unregister_pm_notifier(&video->pm_nb);
1819 
1820 	mutex_lock(&video->device_list_lock);
1821 	list_for_each_entry(dev, &video->video_device_list, entry)
1822 		acpi_video_dev_unregister_backlight(dev);
1823 	mutex_unlock(&video->device_list_lock);
1824 
1825 	video->backlight_registered = false;
1826 
1827 	return error;
1828 }
1829 
1830 static void acpi_video_dev_add_notify_handler(struct acpi_video_device *device)
1831 {
1832 	acpi_status status;
1833 	struct acpi_device *adev = device->dev;
1834 
1835 	status = acpi_install_notify_handler(adev->handle, ACPI_DEVICE_NOTIFY,
1836 					     acpi_video_device_notify, device);
1837 	if (ACPI_FAILURE(status))
1838 		dev_err(&adev->dev, "Error installing notify handler\n");
1839 	else
1840 		device->flags.notify = 1;
1841 }
1842 
1843 static int acpi_video_bus_add_notify_handler(struct acpi_video_bus *video)
1844 {
1845 	struct input_dev *input;
1846 	struct acpi_video_device *dev;
1847 	int error;
1848 
1849 	video->input = input = input_allocate_device();
1850 	if (!input) {
1851 		error = -ENOMEM;
1852 		goto out;
1853 	}
1854 
1855 	error = acpi_video_bus_start_devices(video);
1856 	if (error)
1857 		goto err_free_input;
1858 
1859 	snprintf(video->phys, sizeof(video->phys),
1860 			"%s/video/input0", acpi_device_hid(video->device));
1861 
1862 	input->name = acpi_device_name(video->device);
1863 	input->phys = video->phys;
1864 	input->id.bustype = BUS_HOST;
1865 	input->id.product = 0x06;
1866 	input->dev.parent = &video->device->dev;
1867 	input->evbit[0] = BIT(EV_KEY);
1868 	set_bit(KEY_SWITCHVIDEOMODE, input->keybit);
1869 	set_bit(KEY_VIDEO_NEXT, input->keybit);
1870 	set_bit(KEY_VIDEO_PREV, input->keybit);
1871 	set_bit(KEY_BRIGHTNESS_CYCLE, input->keybit);
1872 	set_bit(KEY_BRIGHTNESSUP, input->keybit);
1873 	set_bit(KEY_BRIGHTNESSDOWN, input->keybit);
1874 	set_bit(KEY_BRIGHTNESS_ZERO, input->keybit);
1875 	set_bit(KEY_DISPLAY_OFF, input->keybit);
1876 
1877 	error = input_register_device(input);
1878 	if (error)
1879 		goto err_stop_dev;
1880 
1881 	mutex_lock(&video->device_list_lock);
1882 	list_for_each_entry(dev, &video->video_device_list, entry)
1883 		acpi_video_dev_add_notify_handler(dev);
1884 	mutex_unlock(&video->device_list_lock);
1885 
1886 	return 0;
1887 
1888 err_stop_dev:
1889 	acpi_video_bus_stop_devices(video);
1890 err_free_input:
1891 	input_free_device(input);
1892 	video->input = NULL;
1893 out:
1894 	return error;
1895 }
1896 
1897 static void acpi_video_dev_remove_notify_handler(struct acpi_video_device *dev)
1898 {
1899 	if (dev->flags.notify) {
1900 		acpi_remove_notify_handler(dev->dev->handle, ACPI_DEVICE_NOTIFY,
1901 					   acpi_video_device_notify);
1902 		dev->flags.notify = 0;
1903 	}
1904 }
1905 
1906 static void acpi_video_bus_remove_notify_handler(struct acpi_video_bus *video)
1907 {
1908 	struct acpi_video_device *dev;
1909 
1910 	mutex_lock(&video->device_list_lock);
1911 	list_for_each_entry(dev, &video->video_device_list, entry)
1912 		acpi_video_dev_remove_notify_handler(dev);
1913 	mutex_unlock(&video->device_list_lock);
1914 
1915 	acpi_video_bus_stop_devices(video);
1916 	input_unregister_device(video->input);
1917 	video->input = NULL;
1918 }
1919 
1920 static int acpi_video_bus_put_devices(struct acpi_video_bus *video)
1921 {
1922 	struct acpi_video_device *dev, *next;
1923 
1924 	mutex_lock(&video->device_list_lock);
1925 	list_for_each_entry_safe(dev, next, &video->video_device_list, entry) {
1926 		list_del(&dev->entry);
1927 		kfree(dev);
1928 	}
1929 	mutex_unlock(&video->device_list_lock);
1930 
1931 	return 0;
1932 }
1933 
1934 static int instance;
1935 
1936 static int acpi_video_bus_add(struct acpi_device *device)
1937 {
1938 	struct acpi_video_bus *video;
1939 	int error;
1940 	acpi_status status;
1941 
1942 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
1943 				device->parent->handle, 1,
1944 				acpi_video_bus_match, NULL,
1945 				device, NULL);
1946 	if (status == AE_ALREADY_EXISTS) {
1947 		printk(KERN_WARNING FW_BUG
1948 			"Duplicate ACPI video bus devices for the"
1949 			" same VGA controller, please try module "
1950 			"parameter \"video.allow_duplicates=1\""
1951 			"if the current driver doesn't work.\n");
1952 		if (!allow_duplicates)
1953 			return -ENODEV;
1954 	}
1955 
1956 	video = kzalloc(sizeof(struct acpi_video_bus), GFP_KERNEL);
1957 	if (!video)
1958 		return -ENOMEM;
1959 
1960 	/* a hack to fix the duplicate name "VID" problem on T61 */
1961 	if (!strcmp(device->pnp.bus_id, "VID")) {
1962 		if (instance)
1963 			device->pnp.bus_id[3] = '0' + instance;
1964 		instance++;
1965 	}
1966 	/* a hack to fix the duplicate name "VGA" problem on Pa 3553 */
1967 	if (!strcmp(device->pnp.bus_id, "VGA")) {
1968 		if (instance)
1969 			device->pnp.bus_id[3] = '0' + instance;
1970 		instance++;
1971 	}
1972 
1973 	video->device = device;
1974 	strcpy(acpi_device_name(device), ACPI_VIDEO_BUS_NAME);
1975 	strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);
1976 	device->driver_data = video;
1977 
1978 	acpi_video_bus_find_cap(video);
1979 	error = acpi_video_bus_check(video);
1980 	if (error)
1981 		goto err_free_video;
1982 
1983 	mutex_init(&video->device_list_lock);
1984 	INIT_LIST_HEAD(&video->video_device_list);
1985 
1986 	error = acpi_video_bus_get_devices(video, device);
1987 	if (error)
1988 		goto err_put_video;
1989 
1990 	printk(KERN_INFO PREFIX "%s [%s] (multi-head: %s  rom: %s  post: %s)\n",
1991 	       ACPI_VIDEO_DEVICE_NAME, acpi_device_bid(device),
1992 	       video->flags.multihead ? "yes" : "no",
1993 	       video->flags.rom ? "yes" : "no",
1994 	       video->flags.post ? "yes" : "no");
1995 	mutex_lock(&video_list_lock);
1996 	list_add_tail(&video->entry, &video_bus_head);
1997 	mutex_unlock(&video_list_lock);
1998 
1999 	acpi_video_bus_register_backlight(video);
2000 	acpi_video_bus_add_notify_handler(video);
2001 
2002 	return 0;
2003 
2004 err_put_video:
2005 	acpi_video_bus_put_devices(video);
2006 	kfree(video->attached_array);
2007 err_free_video:
2008 	kfree(video);
2009 	device->driver_data = NULL;
2010 
2011 	return error;
2012 }
2013 
2014 static int acpi_video_bus_remove(struct acpi_device *device)
2015 {
2016 	struct acpi_video_bus *video = NULL;
2017 
2018 
2019 	if (!device || !acpi_driver_data(device))
2020 		return -EINVAL;
2021 
2022 	video = acpi_driver_data(device);
2023 
2024 	acpi_video_bus_remove_notify_handler(video);
2025 	acpi_video_bus_unregister_backlight(video);
2026 	acpi_video_bus_put_devices(video);
2027 
2028 	mutex_lock(&video_list_lock);
2029 	list_del(&video->entry);
2030 	mutex_unlock(&video_list_lock);
2031 
2032 	kfree(video->attached_array);
2033 	kfree(video);
2034 
2035 	return 0;
2036 }
2037 
2038 static int __init is_i740(struct pci_dev *dev)
2039 {
2040 	if (dev->device == 0x00D1)
2041 		return 1;
2042 	if (dev->device == 0x7000)
2043 		return 1;
2044 	return 0;
2045 }
2046 
2047 static int __init intel_opregion_present(void)
2048 {
2049 	int opregion = 0;
2050 	struct pci_dev *dev = NULL;
2051 	u32 address;
2052 
2053 	for_each_pci_dev(dev) {
2054 		if ((dev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
2055 			continue;
2056 		if (dev->vendor != PCI_VENDOR_ID_INTEL)
2057 			continue;
2058 		/* We don't want to poke around undefined i740 registers */
2059 		if (is_i740(dev))
2060 			continue;
2061 		pci_read_config_dword(dev, 0xfc, &address);
2062 		if (!address)
2063 			continue;
2064 		opregion = 1;
2065 	}
2066 	return opregion;
2067 }
2068 
2069 int acpi_video_register(void)
2070 {
2071 	int ret = 0;
2072 
2073 	mutex_lock(&register_count_mutex);
2074 	if (register_count) {
2075 		/*
2076 		 * if the function of acpi_video_register is already called,
2077 		 * don't register the acpi_vide_bus again and return no error.
2078 		 */
2079 		goto leave;
2080 	}
2081 
2082 	dmi_check_system(video_dmi_table);
2083 
2084 	ret = acpi_bus_register_driver(&acpi_video_bus);
2085 	if (ret)
2086 		goto leave;
2087 
2088 	/*
2089 	 * When the acpi_video_bus is loaded successfully, increase
2090 	 * the counter reference.
2091 	 */
2092 	register_count = 1;
2093 
2094 leave:
2095 	mutex_unlock(&register_count_mutex);
2096 	return ret;
2097 }
2098 EXPORT_SYMBOL(acpi_video_register);
2099 
2100 void acpi_video_unregister(void)
2101 {
2102 	mutex_lock(&register_count_mutex);
2103 	if (register_count) {
2104 		acpi_bus_unregister_driver(&acpi_video_bus);
2105 		register_count = 0;
2106 	}
2107 	mutex_unlock(&register_count_mutex);
2108 }
2109 EXPORT_SYMBOL(acpi_video_unregister);
2110 
2111 void acpi_video_unregister_backlight(void)
2112 {
2113 	struct acpi_video_bus *video;
2114 
2115 	mutex_lock(&register_count_mutex);
2116 	if (register_count) {
2117 		mutex_lock(&video_list_lock);
2118 		list_for_each_entry(video, &video_bus_head, entry)
2119 			acpi_video_bus_unregister_backlight(video);
2120 		mutex_unlock(&video_list_lock);
2121 	}
2122 	mutex_unlock(&register_count_mutex);
2123 }
2124 
2125 bool acpi_video_handles_brightness_key_presses(void)
2126 {
2127 	bool have_video_busses;
2128 
2129 	mutex_lock(&video_list_lock);
2130 	have_video_busses = !list_empty(&video_bus_head);
2131 	mutex_unlock(&video_list_lock);
2132 
2133 	return have_video_busses &&
2134 	       (report_key_events & REPORT_BRIGHTNESS_KEY_EVENTS);
2135 }
2136 EXPORT_SYMBOL(acpi_video_handles_brightness_key_presses);
2137 
2138 /*
2139  * This is kind of nasty. Hardware using Intel chipsets may require
2140  * the video opregion code to be run first in order to initialise
2141  * state before any ACPI video calls are made. To handle this we defer
2142  * registration of the video class until the opregion code has run.
2143  */
2144 
2145 static int __init acpi_video_init(void)
2146 {
2147 	/*
2148 	 * Let the module load even if ACPI is disabled (e.g. due to
2149 	 * a broken BIOS) so that i915.ko can still be loaded on such
2150 	 * old systems without an AcpiOpRegion.
2151 	 *
2152 	 * acpi_video_register() will report -ENODEV later as well due
2153 	 * to acpi_disabled when i915.ko tries to register itself afterwards.
2154 	 */
2155 	if (acpi_disabled)
2156 		return 0;
2157 
2158 	if (intel_opregion_present())
2159 		return 0;
2160 
2161 	return acpi_video_register();
2162 }
2163 
2164 static void __exit acpi_video_exit(void)
2165 {
2166 	acpi_video_detect_exit();
2167 	acpi_video_unregister();
2168 
2169 	return;
2170 }
2171 
2172 module_init(acpi_video_init);
2173 module_exit(acpi_video_exit);
2174