Version:  2.0.40 2.2.26 2.4.37 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19

Linux/drivers/acpi/video.c

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

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