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