xref: /openbmc/linux/drivers/acpi/acpi_video.c (revision 3ddc8b84)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  video.c - ACPI Video Driver
4  *
5  *  Copyright (C) 2004 Luming Yu <luming.yu@intel.com>
6  *  Copyright (C) 2004 Bruno Ducrot <ducrot@poupinou.org>
7  *  Copyright (C) 2006 Thomas Tuttle <linux-kernel@ttuttle.net>
8  */
9 
10 #define pr_fmt(fmt) "ACPI: video: " fmt
11 
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/init.h>
15 #include <linux/types.h>
16 #include <linux/list.h>
17 #include <linux/mutex.h>
18 #include <linux/input.h>
19 #include <linux/backlight.h>
20 #include <linux/thermal.h>
21 #include <linux/sort.h>
22 #include <linux/pci.h>
23 #include <linux/pci_ids.h>
24 #include <linux/slab.h>
25 #include <linux/dmi.h>
26 #include <linux/suspend.h>
27 #include <linux/acpi.h>
28 #include <acpi/video.h>
29 #include <linux/uaccess.h>
30 
31 #define ACPI_VIDEO_BUS_NAME		"Video Bus"
32 #define ACPI_VIDEO_DEVICE_NAME		"Video Device"
33 
34 #define MAX_NAME_LEN	20
35 
36 MODULE_AUTHOR("Bruno Ducrot");
37 MODULE_DESCRIPTION("ACPI Video Driver");
38 MODULE_LICENSE("GPL");
39 
40 static bool brightness_switch_enabled = true;
41 module_param(brightness_switch_enabled, bool, 0644);
42 
43 /*
44  * By default, we don't allow duplicate ACPI video bus devices
45  * under the same VGA controller
46  */
47 static bool allow_duplicates;
48 module_param(allow_duplicates, bool, 0644);
49 
50 #define REPORT_OUTPUT_KEY_EVENTS		0x01
51 #define REPORT_BRIGHTNESS_KEY_EVENTS		0x02
52 static int report_key_events = -1;
53 module_param(report_key_events, int, 0644);
54 MODULE_PARM_DESC(report_key_events,
55 	"0: none, 1: output changes, 2: brightness changes, 3: all");
56 
57 static int hw_changes_brightness = -1;
58 module_param(hw_changes_brightness, int, 0644);
59 MODULE_PARM_DESC(hw_changes_brightness,
60 	"Set this to 1 on buggy hw which changes the brightness itself when "
61 	"a hotkey is pressed: -1: auto, 0: normal 1: hw-changes-brightness");
62 
63 /*
64  * Whether the struct acpi_video_device_attrib::device_id_scheme bit should be
65  * assumed even if not actually set.
66  */
67 static bool device_id_scheme = false;
68 module_param(device_id_scheme, bool, 0444);
69 
70 static int only_lcd = -1;
71 module_param(only_lcd, int, 0444);
72 
73 static bool may_report_brightness_keys;
74 static int register_count;
75 static DEFINE_MUTEX(register_count_mutex);
76 static DEFINE_MUTEX(video_list_lock);
77 static LIST_HEAD(video_bus_head);
78 static int acpi_video_bus_add(struct acpi_device *device);
79 static void acpi_video_bus_remove(struct acpi_device *device);
80 static void acpi_video_bus_notify(acpi_handle handle, u32 event, void *data);
81 
82 /*
83  * Indices in the _BCL method response: the first two items are special,
84  * the rest are all supported levels.
85  *
86  * See page 575 of the ACPI spec 3.0
87  */
88 enum acpi_video_level_idx {
89 	ACPI_VIDEO_AC_LEVEL,		/* level when machine has full power */
90 	ACPI_VIDEO_BATTERY_LEVEL,	/* level when machine is on batteries */
91 	ACPI_VIDEO_FIRST_LEVEL,		/* actual supported levels begin here */
92 };
93 
94 static const struct acpi_device_id video_device_ids[] = {
95 	{ACPI_VIDEO_HID, 0},
96 	{"", 0},
97 };
98 MODULE_DEVICE_TABLE(acpi, video_device_ids);
99 
100 static struct acpi_driver acpi_video_bus = {
101 	.name = "video",
102 	.class = ACPI_VIDEO_CLASS,
103 	.ids = video_device_ids,
104 	.ops = {
105 		.add = acpi_video_bus_add,
106 		.remove = acpi_video_bus_remove,
107 		},
108 };
109 
110 struct acpi_video_bus_flags {
111 	u8 multihead:1;		/* can switch video heads */
112 	u8 rom:1;		/* can retrieve a video rom */
113 	u8 post:1;		/* can configure the head to */
114 	u8 reserved:5;
115 };
116 
117 struct acpi_video_bus_cap {
118 	u8 _DOS:1;		/* Enable/Disable output switching */
119 	u8 _DOD:1;		/* Enumerate all devices attached to display adapter */
120 	u8 _ROM:1;		/* Get ROM Data */
121 	u8 _GPD:1;		/* Get POST Device */
122 	u8 _SPD:1;		/* Set POST Device */
123 	u8 _VPO:1;		/* Video POST Options */
124 	u8 reserved:2;
125 };
126 
127 struct acpi_video_device_attrib {
128 	u32 display_index:4;	/* A zero-based instance of the Display */
129 	u32 display_port_attachment:4;	/* This field differentiates the display type */
130 	u32 display_type:4;	/* Describe the specific type in use */
131 	u32 vendor_specific:4;	/* Chipset Vendor Specific */
132 	u32 bios_can_detect:1;	/* BIOS can detect the device */
133 	u32 depend_on_vga:1;	/* Non-VGA output device whose power is related to
134 				   the VGA device. */
135 	u32 pipe_id:3;		/* For VGA multiple-head devices. */
136 	u32 reserved:10;	/* Must be 0 */
137 
138 	/*
139 	 * The device ID might not actually follow the scheme described by this
140 	 * struct acpi_video_device_attrib. If it does, then this bit
141 	 * device_id_scheme is set; otherwise, other fields should be ignored.
142 	 *
143 	 * (but also see the global flag device_id_scheme)
144 	 */
145 	u32 device_id_scheme:1;
146 };
147 
148 struct acpi_video_enumerated_device {
149 	union {
150 		u32 int_val;
151 		struct acpi_video_device_attrib attrib;
152 	} value;
153 	struct acpi_video_device *bind_info;
154 };
155 
156 struct acpi_video_bus {
157 	struct acpi_device *device;
158 	bool backlight_registered;
159 	u8 dos_setting;
160 	struct acpi_video_enumerated_device *attached_array;
161 	u8 attached_count;
162 	u8 child_count;
163 	struct acpi_video_bus_cap cap;
164 	struct acpi_video_bus_flags flags;
165 	struct list_head video_device_list;
166 	struct mutex device_list_lock;	/* protects video_device_list */
167 	struct list_head entry;
168 	struct input_dev *input;
169 	char phys[32];	/* for input device */
170 	struct notifier_block pm_nb;
171 };
172 
173 struct acpi_video_device_flags {
174 	u8 crt:1;
175 	u8 lcd:1;
176 	u8 tvout:1;
177 	u8 dvi:1;
178 	u8 bios:1;
179 	u8 unknown:1;
180 	u8 notify:1;
181 	u8 reserved:1;
182 };
183 
184 struct acpi_video_device_cap {
185 	u8 _ADR:1;		/* Return the unique ID */
186 	u8 _BCL:1;		/* Query list of brightness control levels supported */
187 	u8 _BCM:1;		/* Set the brightness level */
188 	u8 _BQC:1;		/* Get current brightness level */
189 	u8 _BCQ:1;		/* Some buggy BIOS uses _BCQ instead of _BQC */
190 	u8 _DDC:1;		/* Return the EDID for this device */
191 };
192 
193 struct acpi_video_device {
194 	unsigned long device_id;
195 	struct acpi_video_device_flags flags;
196 	struct acpi_video_device_cap cap;
197 	struct list_head entry;
198 	struct delayed_work switch_brightness_work;
199 	int switch_brightness_event;
200 	struct acpi_video_bus *video;
201 	struct acpi_device *dev;
202 	struct acpi_video_device_brightness *brightness;
203 	struct backlight_device *backlight;
204 	struct thermal_cooling_device *cooling_dev;
205 };
206 
207 static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data);
208 static void acpi_video_device_rebind(struct acpi_video_bus *video);
209 static void acpi_video_device_bind(struct acpi_video_bus *video,
210 				   struct acpi_video_device *device);
211 static int acpi_video_device_enumerate(struct acpi_video_bus *video);
212 static int acpi_video_device_lcd_set_level(struct acpi_video_device *device,
213 			int level);
214 static int acpi_video_device_lcd_get_level_current(
215 			struct acpi_video_device *device,
216 			unsigned long long *level, bool raw);
217 static int acpi_video_get_next_level(struct acpi_video_device *device,
218 				     u32 level_current, u32 event);
219 static void acpi_video_switch_brightness(struct work_struct *work);
220 
221 /* backlight device sysfs support */
222 static int acpi_video_get_brightness(struct backlight_device *bd)
223 {
224 	unsigned long long cur_level;
225 	int i;
226 	struct acpi_video_device *vd = bl_get_data(bd);
227 
228 	if (acpi_video_device_lcd_get_level_current(vd, &cur_level, false))
229 		return -EINVAL;
230 	for (i = ACPI_VIDEO_FIRST_LEVEL; i < vd->brightness->count; i++) {
231 		if (vd->brightness->levels[i] == cur_level)
232 			return i - ACPI_VIDEO_FIRST_LEVEL;
233 	}
234 	return 0;
235 }
236 
237 static int acpi_video_set_brightness(struct backlight_device *bd)
238 {
239 	int request_level = bd->props.brightness + ACPI_VIDEO_FIRST_LEVEL;
240 	struct acpi_video_device *vd = bl_get_data(bd);
241 
242 	cancel_delayed_work(&vd->switch_brightness_work);
243 	return acpi_video_device_lcd_set_level(vd,
244 				vd->brightness->levels[request_level]);
245 }
246 
247 static const struct backlight_ops acpi_backlight_ops = {
248 	.get_brightness = acpi_video_get_brightness,
249 	.update_status  = acpi_video_set_brightness,
250 };
251 
252 /* thermal cooling device callbacks */
253 static int video_get_max_state(struct thermal_cooling_device *cooling_dev,
254 			       unsigned long *state)
255 {
256 	struct acpi_video_device *video = cooling_dev->devdata;
257 
258 	*state = video->brightness->count - ACPI_VIDEO_FIRST_LEVEL - 1;
259 	return 0;
260 }
261 
262 static int video_get_cur_state(struct thermal_cooling_device *cooling_dev,
263 			       unsigned long *state)
264 {
265 	struct acpi_video_device *video = cooling_dev->devdata;
266 	unsigned long long level;
267 	int offset;
268 
269 	if (acpi_video_device_lcd_get_level_current(video, &level, false))
270 		return -EINVAL;
271 	for (offset = ACPI_VIDEO_FIRST_LEVEL; offset < video->brightness->count;
272 	     offset++)
273 		if (level == video->brightness->levels[offset]) {
274 			*state = video->brightness->count - offset - 1;
275 			return 0;
276 		}
277 
278 	return -EINVAL;
279 }
280 
281 static int
282 video_set_cur_state(struct thermal_cooling_device *cooling_dev, unsigned long state)
283 {
284 	struct acpi_video_device *video = cooling_dev->devdata;
285 	int level;
286 
287 	if (state >= video->brightness->count - ACPI_VIDEO_FIRST_LEVEL)
288 		return -EINVAL;
289 
290 	state = video->brightness->count - state;
291 	level = video->brightness->levels[state - 1];
292 	return acpi_video_device_lcd_set_level(video, level);
293 }
294 
295 static const struct thermal_cooling_device_ops video_cooling_ops = {
296 	.get_max_state = video_get_max_state,
297 	.get_cur_state = video_get_cur_state,
298 	.set_cur_state = video_set_cur_state,
299 };
300 
301 /*
302  * --------------------------------------------------------------------------
303  *                             Video Management
304  * --------------------------------------------------------------------------
305  */
306 
307 static int
308 acpi_video_device_lcd_query_levels(acpi_handle handle,
309 				   union acpi_object **levels)
310 {
311 	int status;
312 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
313 	union acpi_object *obj;
314 
315 
316 	*levels = NULL;
317 
318 	status = acpi_evaluate_object(handle, "_BCL", NULL, &buffer);
319 	if (ACPI_FAILURE(status))
320 		return status;
321 	obj = (union acpi_object *)buffer.pointer;
322 	if (!obj || (obj->type != ACPI_TYPE_PACKAGE)) {
323 		acpi_handle_info(handle, "Invalid _BCL data\n");
324 		status = -EFAULT;
325 		goto err;
326 	}
327 
328 	*levels = obj;
329 
330 	return 0;
331 
332 err:
333 	kfree(buffer.pointer);
334 
335 	return status;
336 }
337 
338 static int
339 acpi_video_device_lcd_set_level(struct acpi_video_device *device, int level)
340 {
341 	int status;
342 	int state;
343 
344 	status = acpi_execute_simple_method(device->dev->handle,
345 					    "_BCM", level);
346 	if (ACPI_FAILURE(status)) {
347 		acpi_handle_info(device->dev->handle, "_BCM evaluation failed\n");
348 		return -EIO;
349 	}
350 
351 	device->brightness->curr = level;
352 	for (state = ACPI_VIDEO_FIRST_LEVEL; state < device->brightness->count;
353 	     state++)
354 		if (level == device->brightness->levels[state]) {
355 			if (device->backlight)
356 				device->backlight->props.brightness =
357 					state - ACPI_VIDEO_FIRST_LEVEL;
358 			return 0;
359 		}
360 
361 	acpi_handle_info(device->dev->handle, "Current brightness invalid\n");
362 	return -EINVAL;
363 }
364 
365 /*
366  * For some buggy _BQC methods, we need to add a constant value to
367  * the _BQC return value to get the actual current brightness level
368  */
369 
370 static int bqc_offset_aml_bug_workaround;
371 static int video_set_bqc_offset(const struct dmi_system_id *d)
372 {
373 	bqc_offset_aml_bug_workaround = 9;
374 	return 0;
375 }
376 
377 static int video_set_device_id_scheme(const struct dmi_system_id *d)
378 {
379 	device_id_scheme = true;
380 	return 0;
381 }
382 
383 static int video_enable_only_lcd(const struct dmi_system_id *d)
384 {
385 	only_lcd = true;
386 	return 0;
387 }
388 
389 static int video_set_report_key_events(const struct dmi_system_id *id)
390 {
391 	if (report_key_events == -1)
392 		report_key_events = (uintptr_t)id->driver_data;
393 	return 0;
394 }
395 
396 static int video_hw_changes_brightness(
397 	const struct dmi_system_id *d)
398 {
399 	if (hw_changes_brightness == -1)
400 		hw_changes_brightness = 1;
401 	return 0;
402 }
403 
404 static const struct dmi_system_id video_dmi_table[] = {
405 	/*
406 	 * Broken _BQC workaround http://bugzilla.kernel.org/show_bug.cgi?id=13121
407 	 */
408 	{
409 	 .callback = video_set_bqc_offset,
410 	 .ident = "Acer Aspire 5720",
411 	 .matches = {
412 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
413 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5720"),
414 		},
415 	},
416 	{
417 	 .callback = video_set_bqc_offset,
418 	 .ident = "Acer Aspire 5710Z",
419 	 .matches = {
420 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
421 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5710Z"),
422 		},
423 	},
424 	{
425 	 .callback = video_set_bqc_offset,
426 	 .ident = "eMachines E510",
427 	 .matches = {
428 		DMI_MATCH(DMI_BOARD_VENDOR, "EMACHINES"),
429 		DMI_MATCH(DMI_PRODUCT_NAME, "eMachines E510"),
430 		},
431 	},
432 	{
433 	 .callback = video_set_bqc_offset,
434 	 .ident = "Acer Aspire 5315",
435 	 .matches = {
436 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
437 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5315"),
438 		},
439 	},
440 	{
441 	 .callback = video_set_bqc_offset,
442 	 .ident = "Acer Aspire 7720",
443 	 .matches = {
444 		DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
445 		DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 7720"),
446 		},
447 	},
448 
449 	/*
450 	 * Some machine's _DOD IDs don't have bit 31(Device ID Scheme) set
451 	 * but the IDs actually follow the Device ID Scheme.
452 	 */
453 	{
454 	 /* https://bugzilla.kernel.org/show_bug.cgi?id=104121 */
455 	 .callback = video_set_device_id_scheme,
456 	 .ident = "ESPRIMO Mobile M9410",
457 	 .matches = {
458 		DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU SIEMENS"),
459 		DMI_MATCH(DMI_PRODUCT_NAME, "ESPRIMO Mobile M9410"),
460 		},
461 	},
462 	/*
463 	 * Some machines have multiple video output devices, but only the one
464 	 * that is the type of LCD can do the backlight control so we should not
465 	 * register backlight interface for other video output devices.
466 	 */
467 	{
468 	 /* https://bugzilla.kernel.org/show_bug.cgi?id=104121 */
469 	 .callback = video_enable_only_lcd,
470 	 .ident = "ESPRIMO Mobile M9410",
471 	 .matches = {
472 		DMI_MATCH(DMI_SYS_VENDOR, "FUJITSU SIEMENS"),
473 		DMI_MATCH(DMI_PRODUCT_NAME, "ESPRIMO Mobile M9410"),
474 		},
475 	},
476 	/*
477 	 * Some machines report wrong key events on the acpi-bus, suppress
478 	 * key event reporting on these.  Note this is only intended to work
479 	 * around events which are plain wrong. In some cases we get double
480 	 * events, in this case acpi-video is considered the canonical source
481 	 * and the events from the other source should be filtered. E.g.
482 	 * by calling acpi_video_handles_brightness_key_presses() from the
483 	 * vendor acpi/wmi driver or by using /lib/udev/hwdb.d/60-keyboard.hwdb
484 	 */
485 	{
486 	 .callback = video_set_report_key_events,
487 	 .driver_data = (void *)((uintptr_t)REPORT_OUTPUT_KEY_EVENTS),
488 	 .ident = "Dell Vostro V131",
489 	 .matches = {
490 		DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
491 		DMI_MATCH(DMI_PRODUCT_NAME, "Vostro V131"),
492 		},
493 	},
494 	{
495 	 .callback = video_set_report_key_events,
496 	 .driver_data = (void *)((uintptr_t)REPORT_BRIGHTNESS_KEY_EVENTS),
497 	 .ident = "Dell Vostro 3350",
498 	 .matches = {
499 		DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
500 		DMI_MATCH(DMI_PRODUCT_NAME, "Vostro 3350"),
501 		},
502 	},
503 	/*
504 	 * Some machines change the brightness themselves when a brightness
505 	 * hotkey gets pressed, despite us telling them not to. In this case
506 	 * acpi_video_device_notify() should only call backlight_force_update(
507 	 * BACKLIGHT_UPDATE_HOTKEY) and not do anything else.
508 	 */
509 	{
510 	 /* https://bugzilla.kernel.org/show_bug.cgi?id=204077 */
511 	 .callback = video_hw_changes_brightness,
512 	 .ident = "Packard Bell EasyNote MZ35",
513 	 .matches = {
514 		DMI_MATCH(DMI_SYS_VENDOR, "Packard Bell"),
515 		DMI_MATCH(DMI_PRODUCT_NAME, "EasyNote MZ35"),
516 		},
517 	},
518 	{}
519 };
520 
521 static unsigned long long
522 acpi_video_bqc_value_to_level(struct acpi_video_device *device,
523 			      unsigned long long bqc_value)
524 {
525 	unsigned long long level;
526 
527 	if (device->brightness->flags._BQC_use_index) {
528 		/*
529 		 * _BQC returns an index that doesn't account for the first 2
530 		 * items with special meaning (see enum acpi_video_level_idx),
531 		 * so we need to compensate for that by offsetting ourselves
532 		 */
533 		if (device->brightness->flags._BCL_reversed)
534 			bqc_value = device->brightness->count -
535 				ACPI_VIDEO_FIRST_LEVEL - 1 - bqc_value;
536 
537 		level = device->brightness->levels[bqc_value +
538 						   ACPI_VIDEO_FIRST_LEVEL];
539 	} else {
540 		level = bqc_value;
541 	}
542 
543 	level += bqc_offset_aml_bug_workaround;
544 
545 	return level;
546 }
547 
548 static int
549 acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
550 					unsigned long long *level, bool raw)
551 {
552 	acpi_status status = AE_OK;
553 	int i;
554 
555 	if (device->cap._BQC || device->cap._BCQ) {
556 		char *buf = device->cap._BQC ? "_BQC" : "_BCQ";
557 
558 		status = acpi_evaluate_integer(device->dev->handle, buf,
559 						NULL, level);
560 		if (ACPI_SUCCESS(status)) {
561 			if (raw) {
562 				/*
563 				 * Caller has indicated he wants the raw
564 				 * value returned by _BQC, so don't furtherly
565 				 * mess with the value.
566 				 */
567 				return 0;
568 			}
569 
570 			*level = acpi_video_bqc_value_to_level(device, *level);
571 
572 			for (i = ACPI_VIDEO_FIRST_LEVEL;
573 			     i < device->brightness->count; i++)
574 				if (device->brightness->levels[i] == *level) {
575 					device->brightness->curr = *level;
576 					return 0;
577 				}
578 			/*
579 			 * BQC returned an invalid level.
580 			 * Stop using it.
581 			 */
582 			acpi_handle_info(device->dev->handle,
583 					 "%s returned an invalid level", buf);
584 			device->cap._BQC = device->cap._BCQ = 0;
585 		} else {
586 			/*
587 			 * Fixme:
588 			 * should we return an error or ignore this failure?
589 			 * dev->brightness->curr is a cached value which stores
590 			 * the correct current backlight level in most cases.
591 			 * ACPI video backlight still works w/ buggy _BQC.
592 			 * http://bugzilla.kernel.org/show_bug.cgi?id=12233
593 			 */
594 			acpi_handle_info(device->dev->handle,
595 					 "%s evaluation failed", buf);
596 			device->cap._BQC = device->cap._BCQ = 0;
597 		}
598 	}
599 
600 	*level = device->brightness->curr;
601 	return 0;
602 }
603 
604 static int
605 acpi_video_device_EDID(struct acpi_video_device *device,
606 		       union acpi_object **edid, ssize_t length)
607 {
608 	int status;
609 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
610 	union acpi_object *obj;
611 	union acpi_object arg0 = { ACPI_TYPE_INTEGER };
612 	struct acpi_object_list args = { 1, &arg0 };
613 
614 
615 	*edid = NULL;
616 
617 	if (!device)
618 		return -ENODEV;
619 	if (length == 128)
620 		arg0.integer.value = 1;
621 	else if (length == 256)
622 		arg0.integer.value = 2;
623 	else
624 		return -EINVAL;
625 
626 	status = acpi_evaluate_object(device->dev->handle, "_DDC", &args, &buffer);
627 	if (ACPI_FAILURE(status))
628 		return -ENODEV;
629 
630 	obj = buffer.pointer;
631 
632 	if (obj && obj->type == ACPI_TYPE_BUFFER)
633 		*edid = obj;
634 	else {
635 		acpi_handle_info(device->dev->handle, "Invalid _DDC data\n");
636 		status = -EFAULT;
637 		kfree(obj);
638 	}
639 
640 	return status;
641 }
642 
643 /* bus */
644 
645 /*
646  *  Arg:
647  *	video		: video bus device pointer
648  *	bios_flag	:
649  *		0.	The system BIOS should NOT automatically switch(toggle)
650  *			the active display output.
651  *		1.	The system BIOS should automatically switch (toggle) the
652  *			active display output. No switch event.
653  *		2.	The _DGS value should be locked.
654  *		3.	The system BIOS should not automatically switch (toggle) the
655  *			active display output, but instead generate the display switch
656  *			event notify code.
657  *	lcd_flag	:
658  *		0.	The system BIOS should automatically control the brightness level
659  *			of the LCD when:
660  *			- the power changes from AC to DC (ACPI appendix B)
661  *			- a brightness hotkey gets pressed (implied by Win7/8 backlight docs)
662  *		1.	The system BIOS should NOT automatically control the brightness
663  *			level of the LCD when:
664  *			- the power changes from AC to DC (ACPI appendix B)
665  *			- a brightness hotkey gets pressed (implied by Win7/8 backlight docs)
666  *  Return Value:
667  *		-EINVAL	wrong arg.
668  */
669 
670 static int
671 acpi_video_bus_DOS(struct acpi_video_bus *video, int bios_flag, int lcd_flag)
672 {
673 	acpi_status status;
674 
675 	if (!video->cap._DOS)
676 		return 0;
677 
678 	if (bios_flag < 0 || bios_flag > 3 || lcd_flag < 0 || lcd_flag > 1)
679 		return -EINVAL;
680 	video->dos_setting = (lcd_flag << 2) | bios_flag;
681 	status = acpi_execute_simple_method(video->device->handle, "_DOS",
682 					    (lcd_flag << 2) | bios_flag);
683 	if (ACPI_FAILURE(status))
684 		return -EIO;
685 
686 	return 0;
687 }
688 
689 /*
690  * Simple comparison function used to sort backlight levels.
691  */
692 
693 static int
694 acpi_video_cmp_level(const void *a, const void *b)
695 {
696 	return *(int *)a - *(int *)b;
697 }
698 
699 /*
700  * Decides if _BQC/_BCQ for this system is usable
701  *
702  * We do this by changing the level first and then read out the current
703  * brightness level, if the value does not match, find out if it is using
704  * index. If not, clear the _BQC/_BCQ capability.
705  */
706 static int acpi_video_bqc_quirk(struct acpi_video_device *device,
707 				int max_level, int current_level)
708 {
709 	struct acpi_video_device_brightness *br = device->brightness;
710 	int result;
711 	unsigned long long level;
712 	int test_level;
713 
714 	/* don't mess with existing known broken systems */
715 	if (bqc_offset_aml_bug_workaround)
716 		return 0;
717 
718 	/*
719 	 * Some systems always report current brightness level as maximum
720 	 * through _BQC, we need to test another value for them. However,
721 	 * there is a subtlety:
722 	 *
723 	 * If the _BCL package ordering is descending, the first level
724 	 * (br->levels[2]) is likely to be 0, and if the number of levels
725 	 * matches the number of steps, we might confuse a returned level to
726 	 * mean the index.
727 	 *
728 	 * For example:
729 	 *
730 	 *     current_level = max_level = 100
731 	 *     test_level = 0
732 	 *     returned level = 100
733 	 *
734 	 * In this case 100 means the level, not the index, and _BCM failed.
735 	 * Still, if the _BCL package ordering is descending, the index of
736 	 * level 0 is also 100, so we assume _BQC is indexed, when it's not.
737 	 *
738 	 * This causes all _BQC calls to return bogus values causing weird
739 	 * behavior from the user's perspective.  For example:
740 	 *
741 	 * xbacklight -set 10; xbacklight -set 20;
742 	 *
743 	 * would flash to 90% and then slowly down to the desired level (20).
744 	 *
745 	 * The solution is simple; test anything other than the first level
746 	 * (e.g. 1).
747 	 */
748 	test_level = current_level == max_level
749 		? br->levels[ACPI_VIDEO_FIRST_LEVEL + 1]
750 		: max_level;
751 
752 	result = acpi_video_device_lcd_set_level(device, test_level);
753 	if (result)
754 		return result;
755 
756 	result = acpi_video_device_lcd_get_level_current(device, &level, true);
757 	if (result)
758 		return result;
759 
760 	if (level != test_level) {
761 		/* buggy _BQC found, need to find out if it uses index */
762 		if (level < br->count) {
763 			if (br->flags._BCL_reversed)
764 				level = br->count - ACPI_VIDEO_FIRST_LEVEL - 1 - level;
765 			if (br->levels[level + ACPI_VIDEO_FIRST_LEVEL] == test_level)
766 				br->flags._BQC_use_index = 1;
767 		}
768 
769 		if (!br->flags._BQC_use_index)
770 			device->cap._BQC = device->cap._BCQ = 0;
771 	}
772 
773 	return 0;
774 }
775 
776 int acpi_video_get_levels(struct acpi_device *device,
777 			  struct acpi_video_device_brightness **dev_br,
778 			  int *pmax_level)
779 {
780 	union acpi_object *obj = NULL;
781 	int i, max_level = 0, count = 0, level_ac_battery = 0;
782 	union acpi_object *o;
783 	struct acpi_video_device_brightness *br = NULL;
784 	int result = 0;
785 	u32 value;
786 
787 	if (ACPI_FAILURE(acpi_video_device_lcd_query_levels(device->handle, &obj))) {
788 		acpi_handle_debug(device->handle,
789 				  "Could not query available LCD brightness level\n");
790 		result = -ENODEV;
791 		goto out;
792 	}
793 
794 	if (obj->package.count < ACPI_VIDEO_FIRST_LEVEL) {
795 		result = -EINVAL;
796 		goto out;
797 	}
798 
799 	br = kzalloc(sizeof(*br), GFP_KERNEL);
800 	if (!br) {
801 		result = -ENOMEM;
802 		goto out;
803 	}
804 
805 	/*
806 	 * Note that we have to reserve 2 extra items (ACPI_VIDEO_FIRST_LEVEL),
807 	 * in order to account for buggy BIOS which don't export the first two
808 	 * special levels (see below)
809 	 */
810 	br->levels = kmalloc_array(obj->package.count + ACPI_VIDEO_FIRST_LEVEL,
811 				   sizeof(*br->levels),
812 				   GFP_KERNEL);
813 	if (!br->levels) {
814 		result = -ENOMEM;
815 		goto out_free;
816 	}
817 
818 	for (i = 0; i < obj->package.count; i++) {
819 		o = (union acpi_object *)&obj->package.elements[i];
820 		if (o->type != ACPI_TYPE_INTEGER) {
821 			acpi_handle_info(device->handle, "Invalid data\n");
822 			continue;
823 		}
824 		value = (u32) o->integer.value;
825 		/* Skip duplicate entries */
826 		if (count > ACPI_VIDEO_FIRST_LEVEL
827 		    && br->levels[count - 1] == value)
828 			continue;
829 
830 		br->levels[count] = value;
831 
832 		if (br->levels[count] > max_level)
833 			max_level = br->levels[count];
834 		count++;
835 	}
836 
837 	/*
838 	 * some buggy BIOS don't export the levels
839 	 * when machine is on AC/Battery in _BCL package.
840 	 * In this case, the first two elements in _BCL packages
841 	 * are also supported brightness levels that OS should take care of.
842 	 */
843 	for (i = ACPI_VIDEO_FIRST_LEVEL; i < count; i++) {
844 		if (br->levels[i] == br->levels[ACPI_VIDEO_AC_LEVEL])
845 			level_ac_battery++;
846 		if (br->levels[i] == br->levels[ACPI_VIDEO_BATTERY_LEVEL])
847 			level_ac_battery++;
848 	}
849 
850 	if (level_ac_battery < ACPI_VIDEO_FIRST_LEVEL) {
851 		level_ac_battery = ACPI_VIDEO_FIRST_LEVEL - level_ac_battery;
852 		br->flags._BCL_no_ac_battery_levels = 1;
853 		for (i = (count - 1 + level_ac_battery);
854 		     i >= ACPI_VIDEO_FIRST_LEVEL; i--)
855 			br->levels[i] = br->levels[i - level_ac_battery];
856 		count += level_ac_battery;
857 	} else if (level_ac_battery > ACPI_VIDEO_FIRST_LEVEL)
858 		acpi_handle_info(device->handle,
859 				 "Too many duplicates in _BCL package");
860 
861 	/* Check if the _BCL package is in a reversed order */
862 	if (max_level == br->levels[ACPI_VIDEO_FIRST_LEVEL]) {
863 		br->flags._BCL_reversed = 1;
864 		sort(&br->levels[ACPI_VIDEO_FIRST_LEVEL],
865 		     count - ACPI_VIDEO_FIRST_LEVEL,
866 		     sizeof(br->levels[ACPI_VIDEO_FIRST_LEVEL]),
867 		     acpi_video_cmp_level, NULL);
868 	} else if (max_level != br->levels[count - 1])
869 		acpi_handle_info(device->handle,
870 				 "Found unordered _BCL package");
871 
872 	br->count = count;
873 	*dev_br = br;
874 	if (pmax_level)
875 		*pmax_level = max_level;
876 
877 out:
878 	kfree(obj);
879 	return result;
880 out_free:
881 	kfree(br);
882 	goto out;
883 }
884 EXPORT_SYMBOL(acpi_video_get_levels);
885 
886 /*
887  *  Arg:
888  *	device	: video output device (LCD, CRT, ..)
889  *
890  *  Return Value:
891  *	Maximum brightness level
892  *
893  *  Allocate and initialize device->brightness.
894  */
895 
896 static int
897 acpi_video_init_brightness(struct acpi_video_device *device)
898 {
899 	int i, max_level = 0;
900 	unsigned long long level, level_old;
901 	struct acpi_video_device_brightness *br = NULL;
902 	int result;
903 
904 	result = acpi_video_get_levels(device->dev, &br, &max_level);
905 	if (result)
906 		return result;
907 	device->brightness = br;
908 
909 	/* _BQC uses INDEX while _BCL uses VALUE in some laptops */
910 	br->curr = level = max_level;
911 
912 	if (!device->cap._BQC)
913 		goto set_level;
914 
915 	result = acpi_video_device_lcd_get_level_current(device,
916 							 &level_old, true);
917 	if (result)
918 		goto out_free_levels;
919 
920 	result = acpi_video_bqc_quirk(device, max_level, level_old);
921 	if (result)
922 		goto out_free_levels;
923 	/*
924 	 * cap._BQC may get cleared due to _BQC is found to be broken
925 	 * in acpi_video_bqc_quirk, so check again here.
926 	 */
927 	if (!device->cap._BQC)
928 		goto set_level;
929 
930 	level = acpi_video_bqc_value_to_level(device, level_old);
931 	/*
932 	 * On some buggy laptops, _BQC returns an uninitialized
933 	 * value when invoked for the first time, i.e.
934 	 * level_old is invalid (no matter whether it's a level
935 	 * or an index). Set the backlight to max_level in this case.
936 	 */
937 	for (i = ACPI_VIDEO_FIRST_LEVEL; i < br->count; i++)
938 		if (level == br->levels[i])
939 			break;
940 	if (i == br->count || !level)
941 		level = max_level;
942 
943 set_level:
944 	result = acpi_video_device_lcd_set_level(device, level);
945 	if (result)
946 		goto out_free_levels;
947 
948 	acpi_handle_debug(device->dev->handle, "found %d brightness levels\n",
949 			  br->count - ACPI_VIDEO_FIRST_LEVEL);
950 
951 	return 0;
952 
953 out_free_levels:
954 	kfree(br->levels);
955 	kfree(br);
956 	device->brightness = NULL;
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 
971 static 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 		acpi_handle_info(device->dev->handle,
983 				 "_BCQ is used instead of _BQC\n");
984 		device->cap._BCQ = 1;
985 	}
986 
987 	if (acpi_has_method(device->dev->handle, "_DDC"))
988 		device->cap._DDC = 1;
989 }
990 
991 /*
992  *  Arg:
993  *	device	: video output device (VGA)
994  *
995  *  Return Value:
996  *	None
997  *
998  *  Find out all required AML methods defined under the video bus device.
999  */
1000 
1001 static void acpi_video_bus_find_cap(struct acpi_video_bus *video)
1002 {
1003 	if (acpi_has_method(video->device->handle, "_DOS"))
1004 		video->cap._DOS = 1;
1005 	if (acpi_has_method(video->device->handle, "_DOD"))
1006 		video->cap._DOD = 1;
1007 	if (acpi_has_method(video->device->handle, "_ROM"))
1008 		video->cap._ROM = 1;
1009 	if (acpi_has_method(video->device->handle, "_GPD"))
1010 		video->cap._GPD = 1;
1011 	if (acpi_has_method(video->device->handle, "_SPD"))
1012 		video->cap._SPD = 1;
1013 	if (acpi_has_method(video->device->handle, "_VPO"))
1014 		video->cap._VPO = 1;
1015 }
1016 
1017 /*
1018  * Check whether the video bus device has required AML method to
1019  * support the desired features
1020  */
1021 
1022 static int acpi_video_bus_check(struct acpi_video_bus *video)
1023 {
1024 	acpi_status status = -ENOENT;
1025 	struct pci_dev *dev;
1026 
1027 	if (!video)
1028 		return -EINVAL;
1029 
1030 	dev = acpi_get_pci_dev(video->device->handle);
1031 	if (!dev)
1032 		return -ENODEV;
1033 	pci_dev_put(dev);
1034 
1035 	/*
1036 	 * Since there is no HID, CID and so on for VGA driver, we have
1037 	 * to check well known required nodes.
1038 	 */
1039 
1040 	/* Does this device support video switching? */
1041 	if (video->cap._DOS || video->cap._DOD) {
1042 		if (!video->cap._DOS) {
1043 			pr_info(FW_BUG "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 */
1072 static struct acpi_video_device_attrib *
1073 acpi_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 
1087 static int
1088 acpi_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 
1103 static int acpi_video_bus_get_one_device(struct acpi_device *device, void *arg)
1104 {
1105 	struct acpi_video_bus *video = arg;
1106 	struct acpi_video_device_attrib *attribute;
1107 	struct acpi_video_device *data;
1108 	unsigned long long device_id;
1109 	acpi_status status;
1110 	int device_type;
1111 
1112 	status = acpi_evaluate_integer(device->handle, "_ADR", NULL, &device_id);
1113 	/* Skip devices without _ADR instead of failing. */
1114 	if (ACPI_FAILURE(status))
1115 		goto exit;
1116 
1117 	data = kzalloc(sizeof(struct acpi_video_device), GFP_KERNEL);
1118 	if (!data) {
1119 		dev_dbg(&device->dev, "Cannot attach\n");
1120 		return -ENOMEM;
1121 	}
1122 
1123 	strcpy(acpi_device_name(device), ACPI_VIDEO_DEVICE_NAME);
1124 	strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);
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 || 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 	if (data->cap._BCM && data->cap._BCL)
1177 		may_report_brightness_keys = true;
1178 
1179 	mutex_lock(&video->device_list_lock);
1180 	list_add_tail(&data->entry, &video->video_device_list);
1181 	mutex_unlock(&video->device_list_lock);
1182 
1183 exit:
1184 	video->child_count++;
1185 	return 0;
1186 }
1187 
1188 /*
1189  *  Arg:
1190  *	video	: video bus device
1191  *
1192  *  Return:
1193  *	none
1194  *
1195  *  Enumerate the video device list of the video bus,
1196  *  bind the ids with the corresponding video devices
1197  *  under the video bus.
1198  */
1199 
1200 static void acpi_video_device_rebind(struct acpi_video_bus *video)
1201 {
1202 	struct acpi_video_device *dev;
1203 
1204 	mutex_lock(&video->device_list_lock);
1205 
1206 	list_for_each_entry(dev, &video->video_device_list, entry)
1207 		acpi_video_device_bind(video, dev);
1208 
1209 	mutex_unlock(&video->device_list_lock);
1210 }
1211 
1212 /*
1213  *  Arg:
1214  *	video	: video bus device
1215  *	device	: video output device under the video
1216  *		bus
1217  *
1218  *  Return:
1219  *	none
1220  *
1221  *  Bind the ids with the corresponding video devices
1222  *  under the video bus.
1223  */
1224 
1225 static void
1226 acpi_video_device_bind(struct acpi_video_bus *video,
1227 		       struct acpi_video_device *device)
1228 {
1229 	struct acpi_video_enumerated_device *ids;
1230 	int i;
1231 
1232 	for (i = 0; i < video->attached_count; i++) {
1233 		ids = &video->attached_array[i];
1234 		if (device->device_id == (ids->value.int_val & 0xffff)) {
1235 			ids->bind_info = device;
1236 			acpi_handle_debug(video->device->handle, "%s: %d\n",
1237 					  __func__, i);
1238 		}
1239 	}
1240 }
1241 
1242 static bool acpi_video_device_in_dod(struct acpi_video_device *device)
1243 {
1244 	struct acpi_video_bus *video = device->video;
1245 	int i;
1246 
1247 	/*
1248 	 * If we have a broken _DOD or we have more than 8 output devices
1249 	 * under the graphics controller node that we can't proper deal with
1250 	 * in the operation region code currently, no need to test.
1251 	 */
1252 	if (!video->attached_count || video->child_count > 8)
1253 		return true;
1254 
1255 	for (i = 0; i < video->attached_count; i++) {
1256 		if ((video->attached_array[i].value.int_val & 0xfff) ==
1257 		    (device->device_id & 0xfff))
1258 			return true;
1259 	}
1260 
1261 	return false;
1262 }
1263 
1264 /*
1265  *  Arg:
1266  *	video	: video bus device
1267  *
1268  *  Return:
1269  *	< 0	: error
1270  *
1271  *  Call _DOD to enumerate all devices attached to display adapter
1272  *
1273  */
1274 
1275 static int acpi_video_device_enumerate(struct acpi_video_bus *video)
1276 {
1277 	int status;
1278 	int count;
1279 	int i;
1280 	struct acpi_video_enumerated_device *active_list;
1281 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
1282 	union acpi_object *dod = NULL;
1283 	union acpi_object *obj;
1284 
1285 	if (!video->cap._DOD)
1286 		return AE_NOT_EXIST;
1287 
1288 	status = acpi_evaluate_object(video->device->handle, "_DOD", NULL, &buffer);
1289 	if (ACPI_FAILURE(status)) {
1290 		acpi_handle_info(video->device->handle,
1291 				 "_DOD evaluation failed: %s\n",
1292 				 acpi_format_exception(status));
1293 		return status;
1294 	}
1295 
1296 	dod = buffer.pointer;
1297 	if (!dod || (dod->type != ACPI_TYPE_PACKAGE)) {
1298 		acpi_handle_info(video->device->handle, "Invalid _DOD data\n");
1299 		status = -EFAULT;
1300 		goto out;
1301 	}
1302 
1303 	acpi_handle_debug(video->device->handle, "Found %d video heads in _DOD\n",
1304 			  dod->package.count);
1305 
1306 	active_list = kcalloc(1 + dod->package.count,
1307 			      sizeof(struct acpi_video_enumerated_device),
1308 			      GFP_KERNEL);
1309 	if (!active_list) {
1310 		status = -ENOMEM;
1311 		goto out;
1312 	}
1313 
1314 	count = 0;
1315 	for (i = 0; i < dod->package.count; i++) {
1316 		obj = &dod->package.elements[i];
1317 
1318 		if (obj->type != ACPI_TYPE_INTEGER) {
1319 			acpi_handle_info(video->device->handle,
1320 					 "Invalid _DOD data in element %d\n", i);
1321 			continue;
1322 		}
1323 
1324 		active_list[count].value.int_val = obj->integer.value;
1325 		active_list[count].bind_info = NULL;
1326 
1327 		acpi_handle_debug(video->device->handle,
1328 				  "_DOD element[%d] = %d\n", i,
1329 				  (int)obj->integer.value);
1330 
1331 		count++;
1332 	}
1333 
1334 	kfree(video->attached_array);
1335 
1336 	video->attached_array = active_list;
1337 	video->attached_count = count;
1338 
1339 out:
1340 	kfree(buffer.pointer);
1341 	return status;
1342 }
1343 
1344 static int
1345 acpi_video_get_next_level(struct acpi_video_device *device,
1346 			  u32 level_current, u32 event)
1347 {
1348 	int min, max, min_above, max_below, i, l, delta = 255;
1349 	max = max_below = 0;
1350 	min = min_above = 255;
1351 	/* Find closest level to level_current */
1352 	for (i = ACPI_VIDEO_FIRST_LEVEL; i < device->brightness->count; i++) {
1353 		l = device->brightness->levels[i];
1354 		if (abs(l - level_current) < abs(delta)) {
1355 			delta = l - level_current;
1356 			if (!delta)
1357 				break;
1358 		}
1359 	}
1360 	/* Adjust level_current to closest available level */
1361 	level_current += delta;
1362 	for (i = ACPI_VIDEO_FIRST_LEVEL; i < device->brightness->count; i++) {
1363 		l = device->brightness->levels[i];
1364 		if (l < min)
1365 			min = l;
1366 		if (l > max)
1367 			max = l;
1368 		if (l < min_above && l > level_current)
1369 			min_above = l;
1370 		if (l > max_below && l < level_current)
1371 			max_below = l;
1372 	}
1373 
1374 	switch (event) {
1375 	case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:
1376 		return (level_current < max) ? min_above : min;
1377 	case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:
1378 		return (level_current < max) ? min_above : max;
1379 	case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:
1380 		return (level_current > min) ? max_below : min;
1381 	case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS:
1382 	case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:
1383 		return 0;
1384 	default:
1385 		return level_current;
1386 	}
1387 }
1388 
1389 static void
1390 acpi_video_switch_brightness(struct work_struct *work)
1391 {
1392 	struct acpi_video_device *device = container_of(to_delayed_work(work),
1393 			     struct acpi_video_device, switch_brightness_work);
1394 	unsigned long long level_current, level_next;
1395 	int event = device->switch_brightness_event;
1396 	int result = -EINVAL;
1397 
1398 	/* no warning message if acpi_backlight=vendor or a quirk is used */
1399 	if (!device->backlight)
1400 		return;
1401 
1402 	if (!device->brightness)
1403 		goto out;
1404 
1405 	result = acpi_video_device_lcd_get_level_current(device,
1406 							 &level_current,
1407 							 false);
1408 	if (result)
1409 		goto out;
1410 
1411 	level_next = acpi_video_get_next_level(device, level_current, event);
1412 
1413 	result = acpi_video_device_lcd_set_level(device, level_next);
1414 
1415 	if (!result)
1416 		backlight_force_update(device->backlight,
1417 				       BACKLIGHT_UPDATE_HOTKEY);
1418 
1419 out:
1420 	if (result)
1421 		acpi_handle_info(device->dev->handle,
1422 				 "Failed to switch brightness\n");
1423 }
1424 
1425 int acpi_video_get_edid(struct acpi_device *device, int type, int device_id,
1426 			void **edid)
1427 {
1428 	struct acpi_video_bus *video;
1429 	struct acpi_video_device *video_device;
1430 	union acpi_object *buffer = NULL;
1431 	acpi_status status;
1432 	int i, length;
1433 
1434 	if (!device || !acpi_driver_data(device))
1435 		return -EINVAL;
1436 
1437 	video = acpi_driver_data(device);
1438 
1439 	for (i = 0; i < video->attached_count; i++) {
1440 		video_device = video->attached_array[i].bind_info;
1441 		length = 256;
1442 
1443 		if (!video_device)
1444 			continue;
1445 
1446 		if (!video_device->cap._DDC)
1447 			continue;
1448 
1449 		if (type) {
1450 			switch (type) {
1451 			case ACPI_VIDEO_DISPLAY_CRT:
1452 				if (!video_device->flags.crt)
1453 					continue;
1454 				break;
1455 			case ACPI_VIDEO_DISPLAY_TV:
1456 				if (!video_device->flags.tvout)
1457 					continue;
1458 				break;
1459 			case ACPI_VIDEO_DISPLAY_DVI:
1460 				if (!video_device->flags.dvi)
1461 					continue;
1462 				break;
1463 			case ACPI_VIDEO_DISPLAY_LCD:
1464 				if (!video_device->flags.lcd)
1465 					continue;
1466 				break;
1467 			}
1468 		} else if (video_device->device_id != device_id) {
1469 			continue;
1470 		}
1471 
1472 		status = acpi_video_device_EDID(video_device, &buffer, length);
1473 
1474 		if (ACPI_FAILURE(status) || !buffer ||
1475 		    buffer->type != ACPI_TYPE_BUFFER) {
1476 			length = 128;
1477 			status = acpi_video_device_EDID(video_device, &buffer,
1478 							length);
1479 			if (ACPI_FAILURE(status) || !buffer ||
1480 			    buffer->type != ACPI_TYPE_BUFFER) {
1481 				continue;
1482 			}
1483 		}
1484 
1485 		*edid = buffer->buffer.pointer;
1486 		return length;
1487 	}
1488 
1489 	return -ENODEV;
1490 }
1491 EXPORT_SYMBOL(acpi_video_get_edid);
1492 
1493 static int
1494 acpi_video_bus_get_devices(struct acpi_video_bus *video,
1495 			   struct acpi_device *device)
1496 {
1497 	/*
1498 	 * There are systems where video module known to work fine regardless
1499 	 * of broken _DOD and ignoring returned value here doesn't cause
1500 	 * any issues later.
1501 	 */
1502 	acpi_video_device_enumerate(video);
1503 
1504 	return acpi_dev_for_each_child(device, acpi_video_bus_get_one_device, video);
1505 }
1506 
1507 /* acpi_video interface */
1508 
1509 /*
1510  * Win8 requires setting bit2 of _DOS to let firmware know it shouldn't
1511  * perform any automatic brightness change on receiving a notification.
1512  */
1513 static int acpi_video_bus_start_devices(struct acpi_video_bus *video)
1514 {
1515 	return acpi_video_bus_DOS(video, 0,
1516 				  acpi_osi_is_win8() ? 1 : 0);
1517 }
1518 
1519 static int acpi_video_bus_stop_devices(struct acpi_video_bus *video)
1520 {
1521 	return acpi_video_bus_DOS(video, 0,
1522 				  acpi_osi_is_win8() ? 0 : 1);
1523 }
1524 
1525 static void acpi_video_bus_notify(acpi_handle handle, u32 event, void *data)
1526 {
1527 	struct acpi_device *device = data;
1528 	struct acpi_video_bus *video = acpi_driver_data(device);
1529 	struct input_dev *input;
1530 	int keycode = 0;
1531 
1532 	if (!video || !video->input)
1533 		return;
1534 
1535 	input = video->input;
1536 
1537 	switch (event) {
1538 	case ACPI_VIDEO_NOTIFY_SWITCH:	/* User requested a switch,
1539 					 * most likely via hotkey. */
1540 		keycode = KEY_SWITCHVIDEOMODE;
1541 		break;
1542 
1543 	case ACPI_VIDEO_NOTIFY_PROBE:	/* User plugged in or removed a video
1544 					 * connector. */
1545 		acpi_video_device_enumerate(video);
1546 		acpi_video_device_rebind(video);
1547 		keycode = KEY_SWITCHVIDEOMODE;
1548 		break;
1549 
1550 	case ACPI_VIDEO_NOTIFY_CYCLE:	/* Cycle Display output hotkey pressed. */
1551 		keycode = KEY_SWITCHVIDEOMODE;
1552 		break;
1553 	case ACPI_VIDEO_NOTIFY_NEXT_OUTPUT:	/* Next Display output hotkey pressed. */
1554 		keycode = KEY_VIDEO_NEXT;
1555 		break;
1556 	case ACPI_VIDEO_NOTIFY_PREV_OUTPUT:	/* previous Display output hotkey pressed. */
1557 		keycode = KEY_VIDEO_PREV;
1558 		break;
1559 
1560 	default:
1561 		acpi_handle_debug(device->handle, "Unsupported event [0x%x]\n",
1562 				  event);
1563 		break;
1564 	}
1565 
1566 	if (acpi_notifier_call_chain(device, event, 0))
1567 		/* Something vetoed the keypress. */
1568 		keycode = 0;
1569 
1570 	if (keycode && (report_key_events & REPORT_OUTPUT_KEY_EVENTS)) {
1571 		input_report_key(input, keycode, 1);
1572 		input_sync(input);
1573 		input_report_key(input, keycode, 0);
1574 		input_sync(input);
1575 	}
1576 }
1577 
1578 static void brightness_switch_event(struct acpi_video_device *video_device,
1579 				    u32 event)
1580 {
1581 	if (!brightness_switch_enabled)
1582 		return;
1583 
1584 	video_device->switch_brightness_event = event;
1585 	schedule_delayed_work(&video_device->switch_brightness_work, HZ / 10);
1586 }
1587 
1588 static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data)
1589 {
1590 	struct acpi_video_device *video_device = data;
1591 	struct acpi_device *device = NULL;
1592 	struct acpi_video_bus *bus;
1593 	struct input_dev *input;
1594 	int keycode = 0;
1595 
1596 	if (!video_device)
1597 		return;
1598 
1599 	device = video_device->dev;
1600 	bus = video_device->video;
1601 	input = bus->input;
1602 
1603 	if (hw_changes_brightness > 0) {
1604 		if (video_device->backlight)
1605 			backlight_force_update(video_device->backlight,
1606 					       BACKLIGHT_UPDATE_HOTKEY);
1607 		acpi_notifier_call_chain(device, event, 0);
1608 		return;
1609 	}
1610 
1611 	switch (event) {
1612 	case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:	/* Cycle brightness */
1613 		brightness_switch_event(video_device, event);
1614 		keycode = KEY_BRIGHTNESS_CYCLE;
1615 		break;
1616 	case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:	/* Increase brightness */
1617 		brightness_switch_event(video_device, event);
1618 		keycode = KEY_BRIGHTNESSUP;
1619 		break;
1620 	case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:	/* Decrease brightness */
1621 		brightness_switch_event(video_device, event);
1622 		keycode = KEY_BRIGHTNESSDOWN;
1623 		break;
1624 	case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS:	/* zero brightness */
1625 		brightness_switch_event(video_device, event);
1626 		keycode = KEY_BRIGHTNESS_ZERO;
1627 		break;
1628 	case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:	/* display device off */
1629 		brightness_switch_event(video_device, event);
1630 		keycode = KEY_DISPLAY_OFF;
1631 		break;
1632 	default:
1633 		acpi_handle_debug(handle, "Unsupported event [0x%x]\n", event);
1634 		break;
1635 	}
1636 
1637 	if (keycode)
1638 		may_report_brightness_keys = true;
1639 
1640 	acpi_notifier_call_chain(device, event, 0);
1641 
1642 	if (keycode && (report_key_events & REPORT_BRIGHTNESS_KEY_EVENTS)) {
1643 		input_report_key(input, keycode, 1);
1644 		input_sync(input);
1645 		input_report_key(input, keycode, 0);
1646 		input_sync(input);
1647 	}
1648 }
1649 
1650 static int acpi_video_resume(struct notifier_block *nb,
1651 				unsigned long val, void *ign)
1652 {
1653 	struct acpi_video_bus *video;
1654 	struct acpi_video_device *video_device;
1655 	int i;
1656 
1657 	switch (val) {
1658 	case PM_POST_HIBERNATION:
1659 	case PM_POST_SUSPEND:
1660 	case PM_POST_RESTORE:
1661 		video = container_of(nb, struct acpi_video_bus, pm_nb);
1662 
1663 		dev_info(&video->device->dev, "Restoring backlight state\n");
1664 
1665 		for (i = 0; i < video->attached_count; i++) {
1666 			video_device = video->attached_array[i].bind_info;
1667 			if (video_device && video_device->brightness)
1668 				acpi_video_device_lcd_set_level(video_device,
1669 						video_device->brightness->curr);
1670 		}
1671 
1672 		return NOTIFY_OK;
1673 	}
1674 	return NOTIFY_DONE;
1675 }
1676 
1677 static acpi_status
1678 acpi_video_bus_match(acpi_handle handle, u32 level, void *context,
1679 			void **return_value)
1680 {
1681 	struct acpi_device *device = context;
1682 	struct acpi_device *sibling;
1683 
1684 	if (handle == device->handle)
1685 		return AE_CTRL_TERMINATE;
1686 
1687 	sibling = acpi_fetch_acpi_dev(handle);
1688 	if (!sibling)
1689 		return AE_OK;
1690 
1691 	if (!strcmp(acpi_device_name(sibling), ACPI_VIDEO_BUS_NAME))
1692 			return AE_ALREADY_EXISTS;
1693 
1694 	return AE_OK;
1695 }
1696 
1697 static void acpi_video_dev_register_backlight(struct acpi_video_device *device)
1698 {
1699 	struct backlight_properties props;
1700 	struct pci_dev *pdev;
1701 	acpi_handle acpi_parent;
1702 	struct device *parent = NULL;
1703 	int result;
1704 	static int count;
1705 	char *name;
1706 
1707 	result = acpi_video_init_brightness(device);
1708 	if (result)
1709 		return;
1710 
1711 	name = kasprintf(GFP_KERNEL, "acpi_video%d", count);
1712 	if (!name)
1713 		return;
1714 	count++;
1715 
1716 	if (ACPI_SUCCESS(acpi_get_parent(device->dev->handle, &acpi_parent))) {
1717 		pdev = acpi_get_pci_dev(acpi_parent);
1718 		if (pdev) {
1719 			parent = &pdev->dev;
1720 			pci_dev_put(pdev);
1721 		}
1722 	}
1723 
1724 	memset(&props, 0, sizeof(struct backlight_properties));
1725 	props.type = BACKLIGHT_FIRMWARE;
1726 	props.max_brightness =
1727 		device->brightness->count - ACPI_VIDEO_FIRST_LEVEL - 1;
1728 	device->backlight = backlight_device_register(name,
1729 						      parent,
1730 						      device,
1731 						      &acpi_backlight_ops,
1732 						      &props);
1733 	kfree(name);
1734 	if (IS_ERR(device->backlight)) {
1735 		device->backlight = NULL;
1736 		return;
1737 	}
1738 
1739 	/*
1740 	 * Save current brightness level in case we have to restore it
1741 	 * before acpi_video_device_lcd_set_level() is called next time.
1742 	 */
1743 	device->backlight->props.brightness =
1744 			acpi_video_get_brightness(device->backlight);
1745 
1746 	device->cooling_dev = thermal_cooling_device_register("LCD", device,
1747 							      &video_cooling_ops);
1748 	if (IS_ERR(device->cooling_dev)) {
1749 		/*
1750 		 * Set cooling_dev to NULL so we don't crash trying to free it.
1751 		 * Also, why the hell we are returning early and not attempt to
1752 		 * register video output if cooling device registration failed?
1753 		 * -- dtor
1754 		 */
1755 		device->cooling_dev = NULL;
1756 		return;
1757 	}
1758 
1759 	dev_info(&device->dev->dev, "registered as cooling_device%d\n",
1760 		 device->cooling_dev->id);
1761 	result = sysfs_create_link(&device->dev->dev.kobj,
1762 			&device->cooling_dev->device.kobj,
1763 			"thermal_cooling");
1764 	if (result)
1765 		pr_info("sysfs link creation failed\n");
1766 
1767 	result = sysfs_create_link(&device->cooling_dev->device.kobj,
1768 			&device->dev->dev.kobj, "device");
1769 	if (result)
1770 		pr_info("Reverse sysfs link creation failed\n");
1771 }
1772 
1773 static void acpi_video_run_bcl_for_osi(struct acpi_video_bus *video)
1774 {
1775 	struct acpi_video_device *dev;
1776 	union acpi_object *levels;
1777 
1778 	mutex_lock(&video->device_list_lock);
1779 	list_for_each_entry(dev, &video->video_device_list, entry) {
1780 		if (!acpi_video_device_lcd_query_levels(dev->dev->handle, &levels))
1781 			kfree(levels);
1782 	}
1783 	mutex_unlock(&video->device_list_lock);
1784 }
1785 
1786 static bool acpi_video_should_register_backlight(struct acpi_video_device *dev)
1787 {
1788 	/*
1789 	 * Do not create backlight device for video output
1790 	 * device that is not in the enumerated list.
1791 	 */
1792 	if (!acpi_video_device_in_dod(dev)) {
1793 		dev_dbg(&dev->dev->dev, "not in _DOD list, ignore\n");
1794 		return false;
1795 	}
1796 
1797 	if (only_lcd)
1798 		return dev->flags.lcd;
1799 	return true;
1800 }
1801 
1802 static int acpi_video_bus_register_backlight(struct acpi_video_bus *video)
1803 {
1804 	struct acpi_video_device *dev;
1805 
1806 	if (video->backlight_registered)
1807 		return 0;
1808 
1809 	if (acpi_video_get_backlight_type() != acpi_backlight_video)
1810 		return 0;
1811 
1812 	mutex_lock(&video->device_list_lock);
1813 	list_for_each_entry(dev, &video->video_device_list, entry) {
1814 		if (acpi_video_should_register_backlight(dev))
1815 			acpi_video_dev_register_backlight(dev);
1816 	}
1817 	mutex_unlock(&video->device_list_lock);
1818 
1819 	video->backlight_registered = true;
1820 
1821 	video->pm_nb.notifier_call = acpi_video_resume;
1822 	video->pm_nb.priority = 0;
1823 	return register_pm_notifier(&video->pm_nb);
1824 }
1825 
1826 static void acpi_video_dev_unregister_backlight(struct acpi_video_device *device)
1827 {
1828 	if (device->backlight) {
1829 		backlight_device_unregister(device->backlight);
1830 		device->backlight = NULL;
1831 	}
1832 	if (device->brightness) {
1833 		kfree(device->brightness->levels);
1834 		kfree(device->brightness);
1835 		device->brightness = NULL;
1836 	}
1837 	if (device->cooling_dev) {
1838 		sysfs_remove_link(&device->dev->dev.kobj, "thermal_cooling");
1839 		sysfs_remove_link(&device->cooling_dev->device.kobj, "device");
1840 		thermal_cooling_device_unregister(device->cooling_dev);
1841 		device->cooling_dev = NULL;
1842 	}
1843 }
1844 
1845 static int acpi_video_bus_unregister_backlight(struct acpi_video_bus *video)
1846 {
1847 	struct acpi_video_device *dev;
1848 	int error;
1849 
1850 	if (!video->backlight_registered)
1851 		return 0;
1852 
1853 	error = unregister_pm_notifier(&video->pm_nb);
1854 
1855 	mutex_lock(&video->device_list_lock);
1856 	list_for_each_entry(dev, &video->video_device_list, entry)
1857 		acpi_video_dev_unregister_backlight(dev);
1858 	mutex_unlock(&video->device_list_lock);
1859 
1860 	video->backlight_registered = false;
1861 
1862 	return error;
1863 }
1864 
1865 static void acpi_video_dev_add_notify_handler(struct acpi_video_device *device)
1866 {
1867 	acpi_status status;
1868 	struct acpi_device *adev = device->dev;
1869 
1870 	status = acpi_install_notify_handler(adev->handle, ACPI_DEVICE_NOTIFY,
1871 					     acpi_video_device_notify, device);
1872 	if (ACPI_FAILURE(status))
1873 		dev_err(&adev->dev, "Error installing notify handler\n");
1874 	else
1875 		device->flags.notify = 1;
1876 }
1877 
1878 static int acpi_video_bus_add_notify_handler(struct acpi_video_bus *video)
1879 {
1880 	struct input_dev *input;
1881 	struct acpi_video_device *dev;
1882 	int error;
1883 
1884 	video->input = input = input_allocate_device();
1885 	if (!input) {
1886 		error = -ENOMEM;
1887 		goto out;
1888 	}
1889 
1890 	error = acpi_video_bus_start_devices(video);
1891 	if (error)
1892 		goto err_free_input;
1893 
1894 	snprintf(video->phys, sizeof(video->phys),
1895 			"%s/video/input0", acpi_device_hid(video->device));
1896 
1897 	input->name = acpi_device_name(video->device);
1898 	input->phys = video->phys;
1899 	input->id.bustype = BUS_HOST;
1900 	input->id.product = 0x06;
1901 	input->dev.parent = &video->device->dev;
1902 	input->evbit[0] = BIT(EV_KEY);
1903 	set_bit(KEY_SWITCHVIDEOMODE, input->keybit);
1904 	set_bit(KEY_VIDEO_NEXT, input->keybit);
1905 	set_bit(KEY_VIDEO_PREV, input->keybit);
1906 	set_bit(KEY_BRIGHTNESS_CYCLE, input->keybit);
1907 	set_bit(KEY_BRIGHTNESSUP, input->keybit);
1908 	set_bit(KEY_BRIGHTNESSDOWN, input->keybit);
1909 	set_bit(KEY_BRIGHTNESS_ZERO, input->keybit);
1910 	set_bit(KEY_DISPLAY_OFF, input->keybit);
1911 
1912 	error = input_register_device(input);
1913 	if (error)
1914 		goto err_stop_dev;
1915 
1916 	mutex_lock(&video->device_list_lock);
1917 	list_for_each_entry(dev, &video->video_device_list, entry)
1918 		acpi_video_dev_add_notify_handler(dev);
1919 	mutex_unlock(&video->device_list_lock);
1920 
1921 	return 0;
1922 
1923 err_stop_dev:
1924 	acpi_video_bus_stop_devices(video);
1925 err_free_input:
1926 	input_free_device(input);
1927 	video->input = NULL;
1928 out:
1929 	return error;
1930 }
1931 
1932 static void acpi_video_dev_remove_notify_handler(struct acpi_video_device *dev)
1933 {
1934 	if (dev->flags.notify) {
1935 		acpi_remove_notify_handler(dev->dev->handle, ACPI_DEVICE_NOTIFY,
1936 					   acpi_video_device_notify);
1937 		dev->flags.notify = 0;
1938 	}
1939 }
1940 
1941 static void acpi_video_bus_remove_notify_handler(struct acpi_video_bus *video)
1942 {
1943 	struct acpi_video_device *dev;
1944 
1945 	mutex_lock(&video->device_list_lock);
1946 	list_for_each_entry(dev, &video->video_device_list, entry)
1947 		acpi_video_dev_remove_notify_handler(dev);
1948 	mutex_unlock(&video->device_list_lock);
1949 
1950 	acpi_video_bus_stop_devices(video);
1951 	input_unregister_device(video->input);
1952 	video->input = NULL;
1953 }
1954 
1955 static int acpi_video_bus_put_devices(struct acpi_video_bus *video)
1956 {
1957 	struct acpi_video_device *dev, *next;
1958 
1959 	mutex_lock(&video->device_list_lock);
1960 	list_for_each_entry_safe(dev, next, &video->video_device_list, entry) {
1961 		list_del(&dev->entry);
1962 		kfree(dev);
1963 	}
1964 	mutex_unlock(&video->device_list_lock);
1965 
1966 	return 0;
1967 }
1968 
1969 static int instance;
1970 
1971 static int acpi_video_bus_add(struct acpi_device *device)
1972 {
1973 	struct acpi_video_bus *video;
1974 	bool auto_detect;
1975 	int error;
1976 	acpi_status status;
1977 
1978 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
1979 				acpi_dev_parent(device)->handle, 1,
1980 				acpi_video_bus_match, NULL,
1981 				device, NULL);
1982 	if (status == AE_ALREADY_EXISTS) {
1983 		pr_info(FW_BUG
1984 			"Duplicate ACPI video bus devices for the"
1985 			" same VGA controller, please try module "
1986 			"parameter \"video.allow_duplicates=1\""
1987 			"if the current driver doesn't work.\n");
1988 		if (!allow_duplicates)
1989 			return -ENODEV;
1990 	}
1991 
1992 	video = kzalloc(sizeof(struct acpi_video_bus), GFP_KERNEL);
1993 	if (!video)
1994 		return -ENOMEM;
1995 
1996 	/* a hack to fix the duplicate name "VID" problem on T61 */
1997 	if (!strcmp(device->pnp.bus_id, "VID")) {
1998 		if (instance)
1999 			device->pnp.bus_id[3] = '0' + instance;
2000 		instance++;
2001 	}
2002 	/* a hack to fix the duplicate name "VGA" problem on Pa 3553 */
2003 	if (!strcmp(device->pnp.bus_id, "VGA")) {
2004 		if (instance)
2005 			device->pnp.bus_id[3] = '0' + instance;
2006 		instance++;
2007 	}
2008 
2009 	video->device = device;
2010 	strcpy(acpi_device_name(device), ACPI_VIDEO_BUS_NAME);
2011 	strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);
2012 	device->driver_data = video;
2013 
2014 	acpi_video_bus_find_cap(video);
2015 	error = acpi_video_bus_check(video);
2016 	if (error)
2017 		goto err_free_video;
2018 
2019 	mutex_init(&video->device_list_lock);
2020 	INIT_LIST_HEAD(&video->video_device_list);
2021 
2022 	error = acpi_video_bus_get_devices(video, device);
2023 	if (error)
2024 		goto err_put_video;
2025 
2026 	/*
2027 	 * HP ZBook Fury 16 G10 requires ACPI video's child devices have _PS0
2028 	 * evaluated to have functional panel brightness control.
2029 	 */
2030 	acpi_device_fix_up_power_children(device);
2031 
2032 	pr_info("%s [%s] (multi-head: %s  rom: %s  post: %s)\n",
2033 	       ACPI_VIDEO_DEVICE_NAME, acpi_device_bid(device),
2034 	       video->flags.multihead ? "yes" : "no",
2035 	       video->flags.rom ? "yes" : "no",
2036 	       video->flags.post ? "yes" : "no");
2037 	mutex_lock(&video_list_lock);
2038 	list_add_tail(&video->entry, &video_bus_head);
2039 	mutex_unlock(&video_list_lock);
2040 
2041 	/*
2042 	 * If backlight-type auto-detection is used then a native backlight may
2043 	 * show up later and this may change the result from video to native.
2044 	 * Therefor normally the userspace visible /sys/class/backlight device
2045 	 * gets registered separately by the GPU driver calling
2046 	 * acpi_video_register_backlight() when an internal panel is detected.
2047 	 * Register the backlight now when not using auto-detection, so that
2048 	 * when the kernel cmdline or DMI-quirks are used the backlight will
2049 	 * get registered even if acpi_video_register_backlight() is not called.
2050 	 */
2051 	acpi_video_run_bcl_for_osi(video);
2052 	if (__acpi_video_get_backlight_type(false, &auto_detect) == acpi_backlight_video &&
2053 	    !auto_detect)
2054 		acpi_video_bus_register_backlight(video);
2055 
2056 	error = acpi_video_bus_add_notify_handler(video);
2057 	if (error)
2058 		goto err_del;
2059 
2060 	error = acpi_dev_install_notify_handler(device, ACPI_DEVICE_NOTIFY,
2061 						acpi_video_bus_notify);
2062 	if (error)
2063 		goto err_remove;
2064 
2065 	return 0;
2066 
2067 err_remove:
2068 	acpi_video_bus_remove_notify_handler(video);
2069 err_del:
2070 	mutex_lock(&video_list_lock);
2071 	list_del(&video->entry);
2072 	mutex_unlock(&video_list_lock);
2073 	acpi_video_bus_unregister_backlight(video);
2074 err_put_video:
2075 	acpi_video_bus_put_devices(video);
2076 	kfree(video->attached_array);
2077 err_free_video:
2078 	kfree(video);
2079 	device->driver_data = NULL;
2080 
2081 	return error;
2082 }
2083 
2084 static void acpi_video_bus_remove(struct acpi_device *device)
2085 {
2086 	struct acpi_video_bus *video = NULL;
2087 
2088 
2089 	if (!device || !acpi_driver_data(device))
2090 		return;
2091 
2092 	video = acpi_driver_data(device);
2093 
2094 	acpi_dev_remove_notify_handler(device, ACPI_DEVICE_NOTIFY,
2095 				       acpi_video_bus_notify);
2096 
2097 	mutex_lock(&video_list_lock);
2098 	list_del(&video->entry);
2099 	mutex_unlock(&video_list_lock);
2100 
2101 	acpi_video_bus_remove_notify_handler(video);
2102 	acpi_video_bus_unregister_backlight(video);
2103 	acpi_video_bus_put_devices(video);
2104 
2105 	kfree(video->attached_array);
2106 	kfree(video);
2107 }
2108 
2109 static int __init is_i740(struct pci_dev *dev)
2110 {
2111 	if (dev->device == 0x00D1)
2112 		return 1;
2113 	if (dev->device == 0x7000)
2114 		return 1;
2115 	return 0;
2116 }
2117 
2118 static int __init intel_opregion_present(void)
2119 {
2120 	int opregion = 0;
2121 	struct pci_dev *dev = NULL;
2122 	u32 address;
2123 
2124 	for_each_pci_dev(dev) {
2125 		if ((dev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
2126 			continue;
2127 		if (dev->vendor != PCI_VENDOR_ID_INTEL)
2128 			continue;
2129 		/* We don't want to poke around undefined i740 registers */
2130 		if (is_i740(dev))
2131 			continue;
2132 		pci_read_config_dword(dev, 0xfc, &address);
2133 		if (!address)
2134 			continue;
2135 		opregion = 1;
2136 	}
2137 	return opregion;
2138 }
2139 
2140 /* Check if the chassis-type indicates there is no builtin LCD panel */
2141 static bool dmi_is_desktop(void)
2142 {
2143 	const char *chassis_type;
2144 	unsigned long type;
2145 
2146 	chassis_type = dmi_get_system_info(DMI_CHASSIS_TYPE);
2147 	if (!chassis_type)
2148 		return false;
2149 
2150 	if (kstrtoul(chassis_type, 10, &type) != 0)
2151 		return false;
2152 
2153 	switch (type) {
2154 	case 0x03: /* Desktop */
2155 	case 0x04: /* Low Profile Desktop */
2156 	case 0x05: /* Pizza Box */
2157 	case 0x06: /* Mini Tower */
2158 	case 0x07: /* Tower */
2159 	case 0x10: /* Lunch Box */
2160 	case 0x11: /* Main Server Chassis */
2161 		return true;
2162 	}
2163 
2164 	return false;
2165 }
2166 
2167 /*
2168  * We're seeing a lot of bogus backlight interfaces on newer machines
2169  * without a LCD such as desktops, servers and HDMI sticks. Checking the
2170  * lcd flag fixes this, enable this by default on any machines which are:
2171  * 1.  Win8 ready (where we also prefer the native backlight driver, so
2172  *     normally the acpi_video code should not register there anyways); *and*
2173  * 2.1 Report a desktop/server DMI chassis-type, or
2174  * 2.2 Are an ACPI-reduced-hardware platform (and thus won't use the EC for
2175        backlight control)
2176  */
2177 static bool should_check_lcd_flag(void)
2178 {
2179 	if (!acpi_osi_is_win8())
2180 		return false;
2181 
2182 	if (dmi_is_desktop())
2183 		return true;
2184 
2185 	if (acpi_reduced_hardware())
2186 		return true;
2187 
2188 	return false;
2189 }
2190 
2191 int acpi_video_register(void)
2192 {
2193 	int ret = 0;
2194 
2195 	mutex_lock(&register_count_mutex);
2196 	if (register_count) {
2197 		/*
2198 		 * if the function of acpi_video_register is already called,
2199 		 * don't register the acpi_video_bus again and return no error.
2200 		 */
2201 		goto leave;
2202 	}
2203 
2204 	if (only_lcd == -1)
2205 		only_lcd = should_check_lcd_flag();
2206 
2207 	dmi_check_system(video_dmi_table);
2208 
2209 	ret = acpi_bus_register_driver(&acpi_video_bus);
2210 	if (ret)
2211 		goto leave;
2212 
2213 	/*
2214 	 * When the acpi_video_bus is loaded successfully, increase
2215 	 * the counter reference.
2216 	 */
2217 	register_count = 1;
2218 
2219 leave:
2220 	mutex_unlock(&register_count_mutex);
2221 	return ret;
2222 }
2223 EXPORT_SYMBOL(acpi_video_register);
2224 
2225 void acpi_video_unregister(void)
2226 {
2227 	mutex_lock(&register_count_mutex);
2228 	if (register_count) {
2229 		acpi_bus_unregister_driver(&acpi_video_bus);
2230 		register_count = 0;
2231 		may_report_brightness_keys = false;
2232 	}
2233 	mutex_unlock(&register_count_mutex);
2234 }
2235 EXPORT_SYMBOL(acpi_video_unregister);
2236 
2237 void acpi_video_register_backlight(void)
2238 {
2239 	struct acpi_video_bus *video;
2240 
2241 	mutex_lock(&video_list_lock);
2242 	list_for_each_entry(video, &video_bus_head, entry)
2243 		acpi_video_bus_register_backlight(video);
2244 	mutex_unlock(&video_list_lock);
2245 }
2246 EXPORT_SYMBOL(acpi_video_register_backlight);
2247 
2248 bool acpi_video_handles_brightness_key_presses(void)
2249 {
2250 	return may_report_brightness_keys &&
2251 	       (report_key_events & REPORT_BRIGHTNESS_KEY_EVENTS);
2252 }
2253 EXPORT_SYMBOL(acpi_video_handles_brightness_key_presses);
2254 
2255 /*
2256  * This is kind of nasty. Hardware using Intel chipsets may require
2257  * the video opregion code to be run first in order to initialise
2258  * state before any ACPI video calls are made. To handle this we defer
2259  * registration of the video class until the opregion code has run.
2260  */
2261 
2262 static int __init acpi_video_init(void)
2263 {
2264 	/*
2265 	 * Let the module load even if ACPI is disabled (e.g. due to
2266 	 * a broken BIOS) so that i915.ko can still be loaded on such
2267 	 * old systems without an AcpiOpRegion.
2268 	 *
2269 	 * acpi_video_register() will report -ENODEV later as well due
2270 	 * to acpi_disabled when i915.ko tries to register itself afterwards.
2271 	 */
2272 	if (acpi_disabled)
2273 		return 0;
2274 
2275 	if (intel_opregion_present())
2276 		return 0;
2277 
2278 	return acpi_video_register();
2279 }
2280 
2281 static void __exit acpi_video_exit(void)
2282 {
2283 	acpi_video_unregister();
2284 }
2285 
2286 module_init(acpi_video_init);
2287 module_exit(acpi_video_exit);
2288