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 = false;
  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         u8 dos_setting;
 154         struct acpi_video_enumerated_device *attached_array;
 155         u8 attached_count;
 156         struct acpi_video_bus_cap cap;
 157         struct acpi_video_bus_flags flags;
 158         struct list_head video_device_list;
 159         struct mutex device_list_lock;  /* protects video_device_list */
 160         struct list_head entry;
 161         struct input_dev *input;
 162         char phys[32];  /* for input device */
 163         struct notifier_block pm_nb;
 164 };
 165
 166 struct acpi_video_device_flags {
 167         u8 crt:1;
 168         u8 lcd:1;
 169         u8 tvout:1;
 170         u8 dvi:1;
 171         u8 bios:1;
 172         u8 unknown:1;
 173         u8 notify:1;
 174         u8 reserved:1;
 175 };
 176
 177 struct acpi_video_device_cap {
 178         u8 _ADR:1;              /* Return the unique ID */
 179         u8 _BCL:1;              /* Query list of brightness control levels supported */
 180         u8 _BCM:1;              /* Set the brightness level */
 181         u8 _BQC:1;              /* Get current brightness level */
 182         u8 _BCQ:1;              /* Some buggy BIOS uses _BCQ instead of _BQC */
 183         u8 _DDC:1;              /* Return the EDID for this device */
 184 };
 185
 186 struct acpi_video_brightness_flags {
 187         u8 _BCL_no_ac_battery_levels:1; /* no AC/Battery levels in _BCL */
 188         u8 _BCL_reversed:1;             /* _BCL package is in a reversed order */
 189         u8 _BQC_use_index:1;            /* _BQC returns an index value */
 190 };
 191
 192 struct acpi_video_device_brightness {
 193         int curr;
 194         int count;
 195         int *levels;
 196         struct acpi_video_brightness_flags flags;
 197 };
 198
 199 struct acpi_video_device {
 200         unsigned long device_id;
 201         struct acpi_video_device_flags flags;
 202         struct acpi_video_device_cap cap;
 203         struct list_head entry;
 204         struct acpi_video_bus *video;
 205         struct acpi_device *dev;
 206         struct acpi_video_device_brightness *brightness;
 207         struct backlight_device *backlight;
 208         struct thermal_cooling_device *cooling_dev;
 209 };
 210
 211 static const char device_decode[][30] = {
 212         "motherboard VGA device",
 213         "PCI VGA device",
 214         "AGP VGA device",
 215         "UNKNOWN",
 216 };
 217
 218 static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data);
 219 static void acpi_video_device_rebind(struct acpi_video_bus *video);
 220 static void acpi_video_device_bind(struct acpi_video_bus *video,
 221                                    struct acpi_video_device *device);
 222 static int acpi_video_device_enumerate(struct acpi_video_bus *video);
 223 static int acpi_video_device_lcd_set_level(struct acpi_video_device *device,
 224                         int level);
 225 static int acpi_video_device_lcd_get_level_current(
 226                         struct acpi_video_device *device,
 227                         unsigned long long *level, bool raw);
 228 static int acpi_video_get_next_level(struct acpi_video_device *device,
 229                                      u32 level_current, u32 event);
 230 static int acpi_video_switch_brightness(struct acpi_video_device *device,
 231                                          int event);
 232
 233 static bool acpi_video_use_native_backlight(void)
 234 {
 235         if (use_native_backlight_param != -1)
 236                 return use_native_backlight_param;
 237         else
 238                 return use_native_backlight_dmi;
 239 }
 240
 241 static bool acpi_video_verify_backlight_support(void)
 242 {
 243         if (acpi_osi_is_win8() && acpi_video_use_native_backlight() &&
 244             backlight_device_registered(BACKLIGHT_RAW))
 245                 return false;
 246         return acpi_video_backlight_support();
 247 }
 248
 249 /* backlight device sysfs support */
 250 static int acpi_video_get_brightness(struct backlight_device *bd)
 251 {
 252         unsigned long long cur_level;
 253         int i;
 254         struct acpi_video_device *vd = bl_get_data(bd);
 255
 256         if (acpi_video_device_lcd_get_level_current(vd, &cur_level, false))
 257                 return -EINVAL;
 258         for (i = 2; i < vd->brightness->count; i++) {
 259                 if (vd->brightness->levels[i] == cur_level)
 260                         /*
 261                          * The first two entries are special - see page 575
 262                          * of the ACPI spec 3.0
 263                          */
 264                         return i - 2;
 265         }
 266         return 0;
 267 }
 268
 269 static int acpi_video_set_brightness(struct backlight_device *bd)
 270 {
 271         int request_level = bd->props.brightness + 2;
 272         struct acpi_video_device *vd = bl_get_data(bd);
 273
 274         return acpi_video_device_lcd_set_level(vd,
 275                                 vd->brightness->levels[request_level]);
 276 }
 277
 278 static const struct backlight_ops acpi_backlight_ops = {
 279         .get_brightness = acpi_video_get_brightness,
 280         .update_status  = acpi_video_set_brightness,
 281 };
 282
 283 /* thermal cooling device callbacks */
 284 static int video_get_max_state(struct thermal_cooling_device *cooling_dev, unsigned
 285                                long *state)
 286 {
 287         struct acpi_device *device = cooling_dev->devdata;
 288         struct acpi_video_device *video = acpi_driver_data(device);
 289
 290         *state = video->brightness->count - 3;
 291         return 0;
 292 }
 293
 294 static int video_get_cur_state(struct thermal_cooling_device *cooling_dev, unsigned
 295                                long *state)
 296 {
 297         struct acpi_device *device = cooling_dev->devdata;
 298         struct acpi_video_device *video = acpi_driver_data(device);
 299         unsigned long long level;
 300         int offset;
 301
 302         if (acpi_video_device_lcd_get_level_current(video, &level, false))
 303                 return -EINVAL;
 304         for (offset = 2; offset < video->brightness->count; offset++)
 305                 if (level == video->brightness->levels[offset]) {
 306                         *state = video->brightness->count - offset - 1;
 307                         return 0;
 308                 }
 309
 310         return -EINVAL;
 311 }
 312
 313 static int
 314 video_set_cur_state(struct thermal_cooling_device *cooling_dev, unsigned long state)
 315 {
 316         struct acpi_device *device = cooling_dev->devdata;
 317         struct acpi_video_device *video = acpi_driver_data(device);
 318         int level;
 319
 320         if (state >= video->brightness->count - 2)
 321                 return -EINVAL;
 322
 323         state = video->brightness->count - state;
 324         level = video->brightness->levels[state - 1];
 325         return acpi_video_device_lcd_set_level(video, level);
 326 }
 327
 328 static const struct thermal_cooling_device_ops video_cooling_ops = {
 329         .get_max_state = video_get_max_state,
 330         .get_cur_state = video_get_cur_state,
 331         .set_cur_state = video_set_cur_state,
 332 };
 333
 334 /*
 335  * --------------------------------------------------------------------------
 336  *                             Video Management
 337  * --------------------------------------------------------------------------
 338  */
 339
 340 static int
 341 acpi_video_device_lcd_query_levels(struct acpi_video_device *device,
 342                                    union acpi_object **levels)
 343 {
 344         int status;
 345         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 346         union acpi_object *obj;
 347
 348
 349         *levels = NULL;
 350
 351         status = acpi_evaluate_object(device->dev->handle, "_BCL", NULL, &buffer);
 352         if (!ACPI_SUCCESS(status))
 353                 return status;
 354         obj = (union acpi_object *)buffer.pointer;
 355         if (!obj || (obj->type != ACPI_TYPE_PACKAGE)) {
 356                 printk(KERN_ERR PREFIX "Invalid _BCL data\n");
 357                 status = -EFAULT;
 358                 goto err;
 359         }
 360
 361         *levels = obj;
 362
 363         return 0;
 364
 365 err:
 366         kfree(buffer.pointer);
 367
 368         return status;
 369 }
 370
 371 static int
 372 acpi_video_device_lcd_set_level(struct acpi_video_device *device, int level)
 373 {
 374         int status;
 375         int state;
 376
 377         status = acpi_execute_simple_method(device->dev->handle,
 378                                             "_BCM", level);
 379         if (ACPI_FAILURE(status)) {
 380                 ACPI_ERROR((AE_INFO, "Evaluating _BCM failed"));
 381                 return -EIO;
 382         }
 383
 384         device->brightness->curr = level;
 385         for (state = 2; state < device->brightness->count; state++)
 386                 if (level == device->brightness->levels[state]) {
 387                         if (device->backlight)
 388                                 device->backlight->props.brightness = state - 2;
 389                         return 0;
 390                 }
 391
 392         ACPI_ERROR((AE_INFO, "Current brightness invalid"));
 393         return -EINVAL;
 394 }
 395
 396 /*
 397  * For some buggy _BQC methods, we need to add a constant value to
 398  * the _BQC return value to get the actual current brightness level
 399  */
 400
 401 static int bqc_offset_aml_bug_workaround;
 402 static int __init video_set_bqc_offset(const struct dmi_system_id *d)
 403 {
 404         bqc_offset_aml_bug_workaround = 9;
 405         return 0;
 406 }
 407
 408 static int __init video_set_use_native_backlight(const struct dmi_system_id *d)
 409 {
 410         use_native_backlight_dmi = true;
 411         return 0;
 412 }
 413
 414 static struct dmi_system_id video_dmi_table[] __initdata = {
 415         /*
 416          * Broken _BQC workaround http://bugzilla.kernel.org/show_bug.cgi?id=13121
 417          */
 418         {
 419          .callback = video_set_bqc_offset,
 420          .ident = "Acer Aspire 5720",
 421          .matches = {
 422                 DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
 423                 DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5720"),
 424                 },
 425         },
 426         {
 427          .callback = video_set_bqc_offset,
 428          .ident = "Acer Aspire 5710Z",
 429          .matches = {
 430                 DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
 431                 DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5710Z"),
 432                 },
 433         },
 434         {
 435          .callback = video_set_bqc_offset,
 436          .ident = "eMachines E510",
 437          .matches = {
 438                 DMI_MATCH(DMI_BOARD_VENDOR, "EMACHINES"),
 439                 DMI_MATCH(DMI_PRODUCT_NAME, "eMachines E510"),
 440                 },
 441         },
 442         {
 443          .callback = video_set_bqc_offset,
 444          .ident = "Acer Aspire 5315",
 445          .matches = {
 446                 DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
 447                 DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5315"),
 448                 },
 449         },
 450         {
 451          .callback = video_set_bqc_offset,
 452          .ident = "Acer Aspire 7720",
 453          .matches = {
 454                 DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
 455                 DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 7720"),
 456                 },
 457         },
 458         {
 459          .callback = video_set_use_native_backlight,
 460          .ident = "ThinkPad T430s",
 461          .matches = {
 462                 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
 463                 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T430s"),
 464                 },
 465         },
 466         {
 467          .callback = video_set_use_native_backlight,
 468          .ident = "ThinkPad X230",
 469          .matches = {
 470                 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
 471                 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X230"),
 472                 },
 473         },
 474         {
 475         .callback = video_set_use_native_backlight,
 476         .ident = "ThinkPad X1 Carbon",
 477         .matches = {
 478                 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
 479                 DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad X1 Carbon"),
 480                 },
 481         },
 482         {
 483          .callback = video_set_use_native_backlight,
 484          .ident = "Lenovo Yoga 13",
 485          .matches = {
 486                 DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
 487                 DMI_MATCH(DMI_PRODUCT_VERSION, "Lenovo IdeaPad Yoga 13"),
 488                 },
 489         },
 490         {
 491          .callback = video_set_use_native_backlight,
 492          .ident = "Dell Inspiron 7520",
 493          .matches = {
 494                 DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
 495                 DMI_MATCH(DMI_PRODUCT_VERSION, "Inspiron 7520"),
 496                 },
 497         },
 498         {
 499          .callback = video_set_use_native_backlight,
 500          .ident = "Acer Aspire 5733Z",
 501          .matches = {
 502                 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
 503                 DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 5733Z"),
 504                 },
 505         },
 506         {
 507          .callback = video_set_use_native_backlight,
 508          .ident = "Acer Aspire V5-431",
 509          .matches = {
 510                 DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
 511                 DMI_MATCH(DMI_PRODUCT_NAME, "Aspire V5-431"),
 512                 },
 513         },
 514         {
 515         .callback = video_set_use_native_backlight,
 516         .ident = "HP ProBook 4340s",
 517         .matches = {
 518                 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
 519                 DMI_MATCH(DMI_PRODUCT_VERSION, "HP ProBook 4340s"),
 520                 },
 521         },
 522         {
 523         .callback = video_set_use_native_backlight,
 524         .ident = "HP ProBook 2013 models",
 525         .matches = {
 526                 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
 527                 DMI_MATCH(DMI_PRODUCT_NAME, "HP ProBook "),
 528                 DMI_MATCH(DMI_PRODUCT_NAME, " G1"),
 529                 },
 530         },
 531         {
 532         .callback = video_set_use_native_backlight,
 533         .ident = "HP EliteBook 2013 models",
 534         .matches = {
 535                 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
 536                 DMI_MATCH(DMI_PRODUCT_NAME, "HP EliteBook "),
 537                 DMI_MATCH(DMI_PRODUCT_NAME, " G1"),
 538                 },
 539         },
 540         {
 541         .callback = video_set_use_native_backlight,
 542         .ident = "HP ZBook 14",
 543         .matches = {
 544                 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
 545                 DMI_MATCH(DMI_PRODUCT_NAME, "HP ZBook 14"),
 546                 },
 547         },
 548         {
 549         .callback = video_set_use_native_backlight,
 550         .ident = "HP ZBook 15",
 551         .matches = {
 552                 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
 553                 DMI_MATCH(DMI_PRODUCT_NAME, "HP ZBook 15"),
 554                 },
 555         },
 556         {
 557         .callback = video_set_use_native_backlight,
 558         .ident = "HP ZBook 17",
 559         .matches = {
 560                 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
 561                 DMI_MATCH(DMI_PRODUCT_NAME, "HP ZBook 17"),
 562                 },
 563         },
 564         {
 565         .callback = video_set_use_native_backlight,
 566         .ident = "HP EliteBook 8780w",
 567         .matches = {
 568                 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
 569                 DMI_MATCH(DMI_PRODUCT_NAME, "HP EliteBook 8780w"),
 570                 },
 571         },
 572         {}
 573 };
 574
 575 static unsigned long long
 576 acpi_video_bqc_value_to_level(struct acpi_video_device *device,
 577                               unsigned long long bqc_value)
 578 {
 579         unsigned long long level;
 580
 581         if (device->brightness->flags._BQC_use_index) {
 582                 /*
 583                  * _BQC returns an index that doesn't account for
 584                  * the first 2 items with special meaning, so we need
 585                  * to compensate for that by offsetting ourselves
 586                  */
 587                 if (device->brightness->flags._BCL_reversed)
 588                         bqc_value = device->brightness->count - 3 - bqc_value;
 589
 590                 level = device->brightness->levels[bqc_value + 2];
 591         } else {
 592                 level = bqc_value;
 593         }
 594
 595         level += bqc_offset_aml_bug_workaround;
 596
 597         return level;
 598 }
 599
 600 static int
 601 acpi_video_device_lcd_get_level_current(struct acpi_video_device *device,
 602                                         unsigned long long *level, bool raw)
 603 {
 604         acpi_status status = AE_OK;
 605         int i;
 606
 607         if (device->cap._BQC || device->cap._BCQ) {
 608                 char *buf = device->cap._BQC ? "_BQC" : "_BCQ";
 609
 610                 status = acpi_evaluate_integer(device->dev->handle, buf,
 611                                                 NULL, level);
 612                 if (ACPI_SUCCESS(status)) {
 613                         if (raw) {
 614                                 /*
 615                                  * Caller has indicated he wants the raw
 616                                  * value returned by _BQC, so don't furtherly
 617                                  * mess with the value.
 618                                  */
 619                                 return 0;
 620                         }
 621
 622                         *level = acpi_video_bqc_value_to_level(device, *level);
 623
 624                         for (i = 2; i < device->brightness->count; i++)
 625                                 if (device->brightness->levels[i] == *level) {
 626                                         device->brightness->curr = *level;
 627                                         return 0;
 628                                 }
 629                         /*
 630                          * BQC returned an invalid level.
 631                          * Stop using it.
 632                          */
 633                         ACPI_WARNING((AE_INFO,
 634                                       "%s returned an invalid level",
 635                                       buf));
 636                         device->cap._BQC = device->cap._BCQ = 0;
 637                 } else {
 638                         /*
 639                          * Fixme:
 640                          * should we return an error or ignore this failure?
 641                          * dev->brightness->curr is a cached value which stores
 642                          * the correct current backlight level in most cases.
 643                          * ACPI video backlight still works w/ buggy _BQC.
 644                          * http://bugzilla.kernel.org/show_bug.cgi?id=12233
 645                          */
 646                         ACPI_WARNING((AE_INFO, "Evaluating %s failed", buf));
 647                         device->cap._BQC = device->cap._BCQ = 0;
 648                 }
 649         }
 650
 651         *level = device->brightness->curr;
 652         return 0;
 653 }
 654
 655 static int
 656 acpi_video_device_EDID(struct acpi_video_device *device,
 657                        union acpi_object **edid, ssize_t length)
 658 {
 659         int status;
 660         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 661         union acpi_object *obj;
 662         union acpi_object arg0 = { ACPI_TYPE_INTEGER };
 663         struct acpi_object_list args = { 1, &arg0 };
 664
 665
 666         *edid = NULL;
 667
 668         if (!device)
 669                 return -ENODEV;
 670         if (length == 128)
 671                 arg0.integer.value = 1;
 672         else if (length == 256)
 673                 arg0.integer.value = 2;
 674         else
 675                 return -EINVAL;
 676
 677         status = acpi_evaluate_object(device->dev->handle, "_DDC", &args, &buffer);
 678         if (ACPI_FAILURE(status))
 679                 return -ENODEV;
 680
 681         obj = buffer.pointer;
 682
 683         if (obj && obj->type == ACPI_TYPE_BUFFER)
 684                 *edid = obj;
 685         else {
 686                 printk(KERN_ERR PREFIX "Invalid _DDC data\n");
 687                 status = -EFAULT;
 688                 kfree(obj);
 689         }
 690
 691         return status;
 692 }
 693
 694 /* bus */
 695
 696 /*
 697  *  Arg:
 698  *      video           : video bus device pointer
 699  *      bios_flag       :
 700  *              0.      The system BIOS should NOT automatically switch(toggle)
 701  *                      the active display output.
 702  *              1.      The system BIOS should automatically switch (toggle) the
 703  *                      active display output. No switch event.
 704  *              2.      The _DGS value should be locked.
 705  *              3.      The system BIOS should not automatically switch (toggle) the
 706  *                      active display output, but instead generate the display switch
 707  *                      event notify code.
 708  *      lcd_flag        :
 709  *              0.      The system BIOS should automatically control the brightness level
 710  *                      of the LCD when the power changes from AC to DC
 711  *              1.      The system BIOS should NOT automatically control the brightness
 712  *                      level of the LCD when the power changes from AC to DC.
 713  *  Return Value:
 714  *              -EINVAL wrong arg.
 715  */
 716
 717 static int
 718 acpi_video_bus_DOS(struct acpi_video_bus *video, int bios_flag, int lcd_flag)
 719 {
 720         acpi_status status;
 721
 722         if (!video->cap._DOS)
 723                 return 0;
 724
 725         if (bios_flag < 0 || bios_flag > 3 || lcd_flag < 0 || lcd_flag > 1)
 726                 return -EINVAL;
 727         video->dos_setting = (lcd_flag << 2) | bios_flag;
 728         status = acpi_execute_simple_method(video->device->handle, "_DOS",
 729                                             (lcd_flag << 2) | bios_flag);
 730         if (ACPI_FAILURE(status))
 731                 return -EIO;
 732
 733         return 0;
 734 }
 735
 736 /*
 737  * Simple comparison function used to sort backlight levels.
 738  */
 739
 740 static int
 741 acpi_video_cmp_level(const void *a, const void *b)
 742 {
 743         return *(int *)a - *(int *)b;
 744 }
 745
 746 /*
 747  * Decides if _BQC/_BCQ for this system is usable
 748  *
 749  * We do this by changing the level first and then read out the current
 750  * brightness level, if the value does not match, find out if it is using
 751  * index. If not, clear the _BQC/_BCQ capability.
 752  */
 753 static int acpi_video_bqc_quirk(struct acpi_video_device *device,
 754                                 int max_level, int current_level)
 755 {
 756         struct acpi_video_device_brightness *br = device->brightness;
 757         int result;
 758         unsigned long long level;
 759         int test_level;
 760
 761         /* don't mess with existing known broken systems */
 762         if (bqc_offset_aml_bug_workaround)
 763                 return 0;
 764
 765         /*
 766          * Some systems always report current brightness level as maximum
 767          * through _BQC, we need to test another value for them.
 768          */
 769         test_level = current_level == max_level ? br->levels[3] : max_level;
 770
 771         result = acpi_video_device_lcd_set_level(device, test_level);
 772         if (result)
 773                 return result;
 774
 775         result = acpi_video_device_lcd_get_level_current(device, &level, true);
 776         if (result)
 777                 return result;
 778
 779         if (level != test_level) {
 780                 /* buggy _BQC found, need to find out if it uses index */
 781                 if (level < br->count) {
 782                         if (br->flags._BCL_reversed)
 783                                 level = br->count - 3 - level;
 784                         if (br->levels[level + 2] == test_level)
 785                                 br->flags._BQC_use_index = 1;
 786                 }
 787
 788                 if (!br->flags._BQC_use_index)
 789                         device->cap._BQC = device->cap._BCQ = 0;
 790         }
 791
 792         return 0;
 793 }
 794
 795
 796 /*
 797  *  Arg:
 798  *      device  : video output device (LCD, CRT, ..)
 799  *
 800  *  Return Value:
 801  *      Maximum brightness level
 802  *
 803  *  Allocate and initialize device->brightness.
 804  */
 805
 806 static int
 807 acpi_video_init_brightness(struct acpi_video_device *device)
 808 {
 809         union acpi_object *obj = NULL;
 810         int i, max_level = 0, count = 0, level_ac_battery = 0;
 811         unsigned long long level, level_old;
 812         union acpi_object *o;
 813         struct acpi_video_device_brightness *br = NULL;
 814         int result = -EINVAL;
 815         u32 value;
 816
 817         if (!ACPI_SUCCESS(acpi_video_device_lcd_query_levels(device, &obj))) {
 818                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Could not query available "
 819                                                 "LCD brightness level\n"));
 820                 goto out;
 821         }
 822
 823         if (obj->package.count < 2)
 824                 goto out;
 825
 826         br = kzalloc(sizeof(*br), GFP_KERNEL);
 827         if (!br) {
 828                 printk(KERN_ERR "can't allocate memory\n");
 829                 result = -ENOMEM;
 830                 goto out;
 831         }
 832
 833         br->levels = kmalloc((obj->package.count + 2) * sizeof *(br->levels),
 834                                 GFP_KERNEL);
 835         if (!br->levels) {
 836                 result = -ENOMEM;
 837                 goto out_free;
 838         }
 839
 840         for (i = 0; i < obj->package.count; i++) {
 841                 o = (union acpi_object *)&obj->package.elements[i];
 842                 if (o->type != ACPI_TYPE_INTEGER) {
 843                         printk(KERN_ERR PREFIX "Invalid data\n");
 844                         continue;
 845                 }
 846                 value = (u32) o->integer.value;
 847                 /* Skip duplicate entries */
 848                 if (count > 2 && br->levels[count - 1] == value)
 849                         continue;
 850
 851                 br->levels[count] = value;
 852
 853                 if (br->levels[count] > max_level)
 854                         max_level = br->levels[count];
 855                 count++;
 856         }
 857
 858         /*
 859          * some buggy BIOS don't export the levels
 860          * when machine is on AC/Battery in _BCL package.
 861          * In this case, the first two elements in _BCL packages
 862          * are also supported brightness levels that OS should take care of.
 863          */
 864         for (i = 2; i < count; i++) {
 865                 if (br->levels[i] == br->levels[0])
 866                         level_ac_battery++;
 867                 if (br->levels[i] == br->levels[1])
 868                         level_ac_battery++;
 869         }
 870
 871         if (level_ac_battery < 2) {
 872                 level_ac_battery = 2 - level_ac_battery;
 873                 br->flags._BCL_no_ac_battery_levels = 1;
 874                 for (i = (count - 1 + level_ac_battery); i >= 2; i--)
 875                         br->levels[i] = br->levels[i - level_ac_battery];
 876                 count += level_ac_battery;
 877         } else if (level_ac_battery > 2)
 878                 ACPI_ERROR((AE_INFO, "Too many duplicates in _BCL package"));
 879
 880         /* Check if the _BCL package is in a reversed order */
 881         if (max_level == br->levels[2]) {
 882                 br->flags._BCL_reversed = 1;
 883                 sort(&br->levels[2], count - 2, sizeof(br->levels[2]),
 884                         acpi_video_cmp_level, NULL);
 885         } else if (max_level != br->levels[count - 1])
 886                 ACPI_ERROR((AE_INFO,
 887                             "Found unordered _BCL package"));
 888
 889         br->count = count;
 890         device->brightness = br;
 891
 892         /* _BQC uses INDEX while _BCL uses VALUE in some laptops */
 893         br->curr = level = max_level;
 894
 895         if (!device->cap._BQC)
 896                 goto set_level;
 897
 898         result = acpi_video_device_lcd_get_level_current(device,
 899                                                          &level_old, true);
 900         if (result)
 901                 goto out_free_levels;
 902
 903         result = acpi_video_bqc_quirk(device, max_level, level_old);
 904         if (result)
 905                 goto out_free_levels;
 906         /*
 907          * cap._BQC may get cleared due to _BQC is found to be broken
 908          * in acpi_video_bqc_quirk, so check again here.
 909          */
 910         if (!device->cap._BQC)
 911                 goto set_level;
 912
 913         level = acpi_video_bqc_value_to_level(device, level_old);
 914         /*
 915          * On some buggy laptops, _BQC returns an uninitialized
 916          * value when invoked for the first time, i.e.
 917          * level_old is invalid (no matter whether it's a level
 918          * or an index). Set the backlight to max_level in this case.
 919          */
 920         for (i = 2; i < br->count; i++)
 921                 if (level == br->levels[i])
 922                         break;
 923         if (i == br->count || !level)
 924                 level = max_level;
 925
 926 set_level:
 927         result = acpi_video_device_lcd_set_level(device, level);
 928         if (result)
 929                 goto out_free_levels;
 930
 931         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 932                           "found %d brightness levels\n", count - 2));
 933         kfree(obj);
 934         return result;
 935
 936 out_free_levels:
 937         kfree(br->levels);
 938 out_free:
 939         kfree(br);
 940 out:
 941         device->brightness = NULL;
 942         kfree(obj);
 943         return result;
 944 }
 945
 946 /*
 947  *  Arg:
 948  *      device  : video output device (LCD, CRT, ..)
 949  *
 950  *  Return Value:
 951  *      None
 952  *
 953  *  Find out all required AML methods defined under the output
 954  *  device.
 955  */
 956
 957 static void acpi_video_device_find_cap(struct acpi_video_device *device)
 958 {
 959         if (acpi_has_method(device->dev->handle, "_ADR"))
 960                 device->cap._ADR = 1;
 961         if (acpi_has_method(device->dev->handle, "_BCL"))
 962                 device->cap._BCL = 1;
 963         if (acpi_has_method(device->dev->handle, "_BCM"))
 964                 device->cap._BCM = 1;
 965         if (acpi_has_method(device->dev->handle, "_BQC")) {
 966                 device->cap._BQC = 1;
 967         } else if (acpi_has_method(device->dev->handle, "_BCQ")) {
 968                 printk(KERN_WARNING FW_BUG "_BCQ is used instead of _BQC\n");
 969                 device->cap._BCQ = 1;
 970         }
 971
 972         if (acpi_has_method(device->dev->handle, "_DDC"))
 973                 device->cap._DDC = 1;
 974 }
 975
 976 /*
 977  *  Arg:
 978  *      device  : video output device (VGA)
 979  *
 980  *  Return Value:
 981  *      None
 982  *
 983  *  Find out all required AML methods defined under the video bus device.
 984  */
 985
 986 static void acpi_video_bus_find_cap(struct acpi_video_bus *video)
 987 {
 988         if (acpi_has_method(video->device->handle, "_DOS"))
 989                 video->cap._DOS = 1;
 990         if (acpi_has_method(video->device->handle, "_DOD"))
 991                 video->cap._DOD = 1;
 992         if (acpi_has_method(video->device->handle, "_ROM"))
 993                 video->cap._ROM = 1;
 994         if (acpi_has_method(video->device->handle, "_GPD"))
 995                 video->cap._GPD = 1;
 996         if (acpi_has_method(video->device->handle, "_SPD"))
 997                 video->cap._SPD = 1;
 998         if (acpi_has_method(video->device->handle, "_VPO"))
 999                 video->cap._VPO = 1;
1000 }
1001
1002 /*
1003  * Check whether the video bus device has required AML method to
1004  * support the desired features
1005  */
1006
1007 static int acpi_video_bus_check(struct acpi_video_bus *video)
1008 {
1009         acpi_status status = -ENOENT;
1010         struct pci_dev *dev;
1011
1012         if (!video)
1013                 return -EINVAL;
1014
1015         dev = acpi_get_pci_dev(video->device->handle);
1016         if (!dev)
1017                 return -ENODEV;
1018         pci_dev_put(dev);
1019
1020         /*
1021          * Since there is no HID, CID and so on for VGA driver, we have
1022          * to check well known required nodes.
1023          */
1024
1025         /* Does this device support video switching? */
1026         if (video->cap._DOS || video->cap._DOD) {
1027                 if (!video->cap._DOS) {
1028                         printk(KERN_WARNING FW_BUG
1029                                 "ACPI(%s) defines _DOD but not _DOS\n",
1030                                 acpi_device_bid(video->device));
1031                 }
1032                 video->flags.multihead = 1;
1033                 status = 0;
1034         }
1035
1036         /* Does this device support retrieving a video ROM? */
1037         if (video->cap._ROM) {
1038                 video->flags.rom = 1;
1039                 status = 0;
1040         }
1041
1042         /* Does this device support configuring which video device to POST? */
1043         if (video->cap._GPD && video->cap._SPD && video->cap._VPO) {
1044                 video->flags.post = 1;
1045                 status = 0;
1046         }
1047
1048         return status;
1049 }
1050
1051 /*
1052  * --------------------------------------------------------------------------
1053  *                               Driver Interface
1054  * --------------------------------------------------------------------------
1055  */
1056
1057 /* device interface */
1058 static struct acpi_video_device_attrib *
1059 acpi_video_get_device_attr(struct acpi_video_bus *video, unsigned long device_id)
1060 {
1061         struct acpi_video_enumerated_device *ids;
1062         int i;
1063
1064         for (i = 0; i < video->attached_count; i++) {
1065                 ids = &video->attached_array[i];
1066                 if ((ids->value.int_val & 0xffff) == device_id)
1067                         return &ids->value.attrib;
1068         }
1069
1070         return NULL;
1071 }
1072
1073 static int
1074 acpi_video_get_device_type(struct acpi_video_bus *video,
1075                            unsigned long device_id)
1076 {
1077         struct acpi_video_enumerated_device *ids;
1078         int i;
1079
1080         for (i = 0; i < video->attached_count; i++) {
1081                 ids = &video->attached_array[i];
1082                 if ((ids->value.int_val & 0xffff) == device_id)
1083                         return ids->value.int_val;
1084         }
1085
1086         return 0;
1087 }
1088
1089 static int
1090 acpi_video_bus_get_one_device(struct acpi_device *device,
1091                               struct acpi_video_bus *video)
1092 {
1093         unsigned long long device_id;
1094         int status, device_type;
1095         struct acpi_video_device *data;
1096         struct acpi_video_device_attrib *attribute;
1097
1098         status =
1099             acpi_evaluate_integer(device->handle, "_ADR", NULL, &device_id);
1100         /* Some device omits _ADR, we skip them instead of fail */
1101         if (ACPI_FAILURE(status))
1102                 return 0;
1103
1104         data = kzalloc(sizeof(struct acpi_video_device), GFP_KERNEL);
1105         if (!data)
1106                 return -ENOMEM;
1107
1108         strcpy(acpi_device_name(device), ACPI_VIDEO_DEVICE_NAME);
1109         strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);
1110         device->driver_data = data;
1111
1112         data->device_id = device_id;
1113         data->video = video;
1114         data->dev = device;
1115
1116         attribute = acpi_video_get_device_attr(video, device_id);
1117
1118         if (attribute && attribute->device_id_scheme) {
1119                 switch (attribute->display_type) {
1120                 case ACPI_VIDEO_DISPLAY_CRT:
1121                         data->flags.crt = 1;
1122                         break;
1123                 case ACPI_VIDEO_DISPLAY_TV:
1124                         data->flags.tvout = 1;
1125                         break;
1126                 case ACPI_VIDEO_DISPLAY_DVI:
1127                         data->flags.dvi = 1;
1128                         break;
1129                 case ACPI_VIDEO_DISPLAY_LCD:
1130                         data->flags.lcd = 1;
1131                         break;
1132                 default:
1133                         data->flags.unknown = 1;
1134                         break;
1135                 }
1136                 if (attribute->bios_can_detect)
1137                         data->flags.bios = 1;
1138         } else {
1139                 /* Check for legacy IDs */
1140                 device_type = acpi_video_get_device_type(video, device_id);
1141                 /* Ignore bits 16 and 18-20 */
1142                 switch (device_type & 0xffe2ffff) {
1143                 case ACPI_VIDEO_DISPLAY_LEGACY_MONITOR:
1144                         data->flags.crt = 1;
1145                         break;
1146                 case ACPI_VIDEO_DISPLAY_LEGACY_PANEL:
1147                         data->flags.lcd = 1;
1148                         break;
1149                 case ACPI_VIDEO_DISPLAY_LEGACY_TV:
1150                         data->flags.tvout = 1;
1151                         break;
1152                 default:
1153                         data->flags.unknown = 1;
1154                 }
1155         }
1156
1157         acpi_video_device_bind(video, data);
1158         acpi_video_device_find_cap(data);
1159
1160         mutex_lock(&video->device_list_lock);
1161         list_add_tail(&data->entry, &video->video_device_list);
1162         mutex_unlock(&video->device_list_lock);
1163
1164         return status;
1165 }
1166
1167 /*
1168  *  Arg:
1169  *      video   : video bus device
1170  *
1171  *  Return:
1172  *      none
1173  *
1174  *  Enumerate the video device list of the video bus,
1175  *  bind the ids with the corresponding video devices
1176  *  under the video bus.
1177  */
1178
1179 static void acpi_video_device_rebind(struct acpi_video_bus *video)
1180 {
1181         struct acpi_video_device *dev;
1182
1183         mutex_lock(&video->device_list_lock);
1184
1185         list_for_each_entry(dev, &video->video_device_list, entry)
1186                 acpi_video_device_bind(video, dev);
1187
1188         mutex_unlock(&video->device_list_lock);
1189 }
1190
1191 /*
1192  *  Arg:
1193  *      video   : video bus device
1194  *      device  : video output device under the video
1195  *              bus
1196  *
1197  *  Return:
1198  *      none
1199  *
1200  *  Bind the ids with the corresponding video devices
1201  *  under the video bus.
1202  */
1203
1204 static void
1205 acpi_video_device_bind(struct acpi_video_bus *video,
1206                        struct acpi_video_device *device)
1207 {
1208         struct acpi_video_enumerated_device *ids;
1209         int i;
1210
1211         for (i = 0; i < video->attached_count; i++) {
1212                 ids = &video->attached_array[i];
1213                 if (device->device_id == (ids->value.int_val & 0xffff)) {
1214                         ids->bind_info = device;
1215                         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "device_bind %d\n", i));
1216                 }
1217         }
1218 }
1219
1220 /*
1221  *  Arg:
1222  *      video   : video bus device
1223  *
1224  *  Return:
1225  *      < 0     : error
1226  *
1227  *  Call _DOD to enumerate all devices attached to display adapter
1228  *
1229  */
1230
1231 static int acpi_video_device_enumerate(struct acpi_video_bus *video)
1232 {
1233         int status;
1234         int count;
1235         int i;
1236         struct acpi_video_enumerated_device *active_list;
1237         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
1238         union acpi_object *dod = NULL;
1239         union acpi_object *obj;
1240
1241         status = acpi_evaluate_object(video->device->handle, "_DOD", NULL, &buffer);
1242         if (!ACPI_SUCCESS(status)) {
1243                 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _DOD"));
1244                 return status;
1245         }
1246
1247         dod = buffer.pointer;
1248         if (!dod || (dod->type != ACPI_TYPE_PACKAGE)) {
1249                 ACPI_EXCEPTION((AE_INFO, status, "Invalid _DOD data"));
1250                 status = -EFAULT;
1251                 goto out;
1252         }
1253
1254         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d video heads in _DOD\n",
1255                           dod->package.count));
1256
1257         active_list = kcalloc(1 + dod->package.count,
1258                               sizeof(struct acpi_video_enumerated_device),
1259                               GFP_KERNEL);
1260         if (!active_list) {
1261                 status = -ENOMEM;
1262                 goto out;
1263         }
1264
1265         count = 0;
1266         for (i = 0; i < dod->package.count; i++) {
1267                 obj = &dod->package.elements[i];
1268
1269                 if (obj->type != ACPI_TYPE_INTEGER) {
1270                         printk(KERN_ERR PREFIX
1271                                 "Invalid _DOD data in element %d\n", i);
1272                         continue;
1273                 }
1274
1275                 active_list[count].value.int_val = obj->integer.value;
1276                 active_list[count].bind_info = NULL;
1277                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "dod element[%d] = %d\n", i,
1278                                   (int)obj->integer.value));
1279                 count++;
1280         }
1281
1282         kfree(video->attached_array);
1283
1284         video->attached_array = active_list;
1285         video->attached_count = count;
1286
1287 out:
1288         kfree(buffer.pointer);
1289         return status;
1290 }
1291
1292 static int
1293 acpi_video_get_next_level(struct acpi_video_device *device,
1294                           u32 level_current, u32 event)
1295 {
1296         int min, max, min_above, max_below, i, l, delta = 255;
1297         max = max_below = 0;
1298         min = min_above = 255;
1299         /* Find closest level to level_current */
1300         for (i = 2; i < device->brightness->count; i++) {
1301                 l = device->brightness->levels[i];
1302                 if (abs(l - level_current) < abs(delta)) {
1303                         delta = l - level_current;
1304                         if (!delta)
1305                                 break;
1306                 }
1307         }
1308         /* Ajust level_current to closest available level */
1309         level_current += delta;
1310         for (i = 2; i < device->brightness->count; i++) {
1311                 l = device->brightness->levels[i];
1312                 if (l < min)
1313                         min = l;
1314                 if (l > max)
1315                         max = l;
1316                 if (l < min_above && l > level_current)
1317                         min_above = l;
1318                 if (l > max_below && l < level_current)
1319                         max_below = l;
1320         }
1321
1322         switch (event) {
1323         case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:
1324                 return (level_current < max) ? min_above : min;
1325         case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:
1326                 return (level_current < max) ? min_above : max;
1327         case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:
1328                 return (level_current > min) ? max_below : min;
1329         case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS:
1330         case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:
1331                 return 0;
1332         default:
1333                 return level_current;
1334         }
1335 }
1336
1337 static int
1338 acpi_video_switch_brightness(struct acpi_video_device *device, int event)
1339 {
1340         unsigned long long level_current, level_next;
1341         int result = -EINVAL;
1342
1343         /* no warning message if acpi_backlight=vendor or a quirk is used */
1344         if (!acpi_video_verify_backlight_support())
1345                 return 0;
1346
1347         if (!device->brightness)
1348                 goto out;
1349
1350         result = acpi_video_device_lcd_get_level_current(device,
1351                                                          &level_current,
1352                                                          false);
1353         if (result)
1354                 goto out;
1355
1356         level_next = acpi_video_get_next_level(device, level_current, event);
1357
1358         result = acpi_video_device_lcd_set_level(device, level_next);
1359
1360         if (!result)
1361                 backlight_force_update(device->backlight,
1362                                        BACKLIGHT_UPDATE_HOTKEY);
1363
1364 out:
1365         if (result)
1366                 printk(KERN_ERR PREFIX "Failed to switch the brightness\n");
1367
1368         return result;
1369 }
1370
1371 int acpi_video_get_edid(struct acpi_device *device, int type, int device_id,
1372                         void **edid)
1373 {
1374         struct acpi_video_bus *video;
1375         struct acpi_video_device *video_device;
1376         union acpi_object *buffer = NULL;
1377         acpi_status status;
1378         int i, length;
1379
1380         if (!device || !acpi_driver_data(device))
1381                 return -EINVAL;
1382
1383         video = acpi_driver_data(device);
1384
1385         for (i = 0; i < video->attached_count; i++) {
1386                 video_device = video->attached_array[i].bind_info;
1387                 length = 256;
1388
1389                 if (!video_device)
1390                         continue;
1391
1392                 if (!video_device->cap._DDC)
1393                         continue;
1394
1395                 if (type) {
1396                         switch (type) {
1397                         case ACPI_VIDEO_DISPLAY_CRT:
1398                                 if (!video_device->flags.crt)
1399                                         continue;
1400                                 break;
1401                         case ACPI_VIDEO_DISPLAY_TV:
1402                                 if (!video_device->flags.tvout)
1403                                         continue;
1404                                 break;
1405                         case ACPI_VIDEO_DISPLAY_DVI:
1406                                 if (!video_device->flags.dvi)
1407                                         continue;
1408                                 break;
1409                         case ACPI_VIDEO_DISPLAY_LCD:
1410                                 if (!video_device->flags.lcd)
1411                                         continue;
1412                                 break;
1413                         }
1414                 } else if (video_device->device_id != device_id) {
1415                         continue;
1416                 }
1417
1418                 status = acpi_video_device_EDID(video_device, &buffer, length);
1419
1420                 if (ACPI_FAILURE(status) || !buffer ||
1421                     buffer->type != ACPI_TYPE_BUFFER) {
1422                         length = 128;
1423                         status = acpi_video_device_EDID(video_device, &buffer,
1424                                                         length);
1425                         if (ACPI_FAILURE(status) || !buffer ||
1426                             buffer->type != ACPI_TYPE_BUFFER) {
1427                                 continue;
1428                         }
1429                 }
1430
1431                 *edid = buffer->buffer.pointer;
1432                 return length;
1433         }
1434
1435         return -ENODEV;
1436 }
1437 EXPORT_SYMBOL(acpi_video_get_edid);
1438
1439 static int
1440 acpi_video_bus_get_devices(struct acpi_video_bus *video,
1441                            struct acpi_device *device)
1442 {
1443         int status = 0;
1444         struct acpi_device *dev;
1445
1446         /*
1447          * There are systems where video module known to work fine regardless
1448          * of broken _DOD and ignoring returned value here doesn't cause
1449          * any issues later.
1450          */
1451         acpi_video_device_enumerate(video);
1452
1453         list_for_each_entry(dev, &device->children, node) {
1454
1455                 status = acpi_video_bus_get_one_device(dev, video);
1456                 if (status) {
1457                         dev_err(&dev->dev, "Can't attach device\n");
1458                         break;
1459                 }
1460         }
1461         return status;
1462 }
1463
1464 /* acpi_video interface */
1465
1466 /*
1467  * Win8 requires setting bit2 of _DOS to let firmware know it shouldn't
1468  * preform any automatic brightness change on receiving a notification.
1469  */
1470 static int acpi_video_bus_start_devices(struct acpi_video_bus *video)
1471 {
1472         return acpi_video_bus_DOS(video, 0,
1473                                   acpi_osi_is_win8() ? 1 : 0);
1474 }
1475
1476 static int acpi_video_bus_stop_devices(struct acpi_video_bus *video)
1477 {
1478         return acpi_video_bus_DOS(video, 0,
1479                                   acpi_osi_is_win8() ? 0 : 1);
1480 }
1481
1482 static void acpi_video_bus_notify(struct acpi_device *device, u32 event)
1483 {
1484         struct acpi_video_bus *video = acpi_driver_data(device);
1485         struct input_dev *input;
1486         int keycode = 0;
1487
1488         if (!video || !video->input)
1489                 return;
1490
1491         input = video->input;
1492
1493         switch (event) {
1494         case ACPI_VIDEO_NOTIFY_SWITCH:  /* User requested a switch,
1495                                          * most likely via hotkey. */
1496                 keycode = KEY_SWITCHVIDEOMODE;
1497                 break;
1498
1499         case ACPI_VIDEO_NOTIFY_PROBE:   /* User plugged in or removed a video
1500                                          * connector. */
1501                 acpi_video_device_enumerate(video);
1502                 acpi_video_device_rebind(video);
1503                 keycode = KEY_SWITCHVIDEOMODE;
1504                 break;
1505
1506         case ACPI_VIDEO_NOTIFY_CYCLE:   /* Cycle Display output hotkey pressed. */
1507                 keycode = KEY_SWITCHVIDEOMODE;
1508                 break;
1509         case ACPI_VIDEO_NOTIFY_NEXT_OUTPUT:     /* Next Display output hotkey pressed. */
1510                 keycode = KEY_VIDEO_NEXT;
1511                 break;
1512         case ACPI_VIDEO_NOTIFY_PREV_OUTPUT:     /* previous Display output hotkey pressed. */
1513                 keycode = KEY_VIDEO_PREV;
1514                 break;
1515
1516         default:
1517                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
1518                                   "Unsupported event [0x%x]\n", event));
1519                 break;
1520         }
1521
1522         if (acpi_notifier_call_chain(device, event, 0))
1523                 /* Something vetoed the keypress. */
1524                 keycode = 0;
1525
1526         if (keycode) {
1527                 input_report_key(input, keycode, 1);
1528                 input_sync(input);
1529                 input_report_key(input, keycode, 0);
1530                 input_sync(input);
1531         }
1532
1533         return;
1534 }
1535
1536 static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data)
1537 {
1538         struct acpi_video_device *video_device = data;
1539         struct acpi_device *device = NULL;
1540         struct acpi_video_bus *bus;
1541         struct input_dev *input;
1542         int keycode = 0;
1543
1544         if (!video_device)
1545                 return;
1546
1547         device = video_device->dev;
1548         bus = video_device->video;
1549         input = bus->input;
1550
1551         switch (event) {
1552         case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:        /* Cycle brightness */
1553                 if (brightness_switch_enabled)
1554                         acpi_video_switch_brightness(video_device, event);
1555                 keycode = KEY_BRIGHTNESS_CYCLE;
1556                 break;
1557         case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:  /* Increase brightness */
1558                 if (brightness_switch_enabled)
1559                         acpi_video_switch_brightness(video_device, event);
1560                 keycode = KEY_BRIGHTNESSUP;
1561                 break;
1562         case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:  /* Decrease brightness */
1563                 if (brightness_switch_enabled)
1564                         acpi_video_switch_brightness(video_device, event);
1565                 keycode = KEY_BRIGHTNESSDOWN;
1566                 break;
1567         case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS: /* zero brightness */
1568                 if (brightness_switch_enabled)
1569                         acpi_video_switch_brightness(video_device, event);
1570                 keycode = KEY_BRIGHTNESS_ZERO;
1571                 break;
1572         case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:     /* display device off */
1573                 if (brightness_switch_enabled)
1574                         acpi_video_switch_brightness(video_device, event);
1575                 keycode = KEY_DISPLAY_OFF;
1576                 break;
1577         default:
1578                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
1579                                   "Unsupported event [0x%x]\n", event));
1580                 break;
1581         }
1582
1583         acpi_notifier_call_chain(device, event, 0);
1584
1585         if (keycode) {
1586                 input_report_key(input, keycode, 1);
1587                 input_sync(input);
1588                 input_report_key(input, keycode, 0);
1589                 input_sync(input);
1590         }
1591
1592         return;
1593 }
1594
1595 static int acpi_video_resume(struct notifier_block *nb,
1596                                 unsigned long val, void *ign)
1597 {
1598         struct acpi_video_bus *video;
1599         struct acpi_video_device *video_device;
1600         int i;
1601
1602         switch (val) {
1603         case PM_HIBERNATION_PREPARE:
1604         case PM_SUSPEND_PREPARE:
1605         case PM_RESTORE_PREPARE:
1606                 return NOTIFY_DONE;
1607         }
1608
1609         video = container_of(nb, struct acpi_video_bus, pm_nb);
1610
1611         dev_info(&video->device->dev, "Restoring backlight state\n");
1612
1613         for (i = 0; i < video->attached_count; i++) {
1614                 video_device = video->attached_array[i].bind_info;
1615                 if (video_device && video_device->backlight)
1616                         acpi_video_set_brightness(video_device->backlight);
1617         }
1618
1619         return NOTIFY_OK;
1620 }
1621
1622 static acpi_status
1623 acpi_video_bus_match(acpi_handle handle, u32 level, void *context,
1624                         void **return_value)
1625 {
1626         struct acpi_device *device = context;
1627         struct acpi_device *sibling;
1628         int result;
1629
1630         if (handle == device->handle)
1631                 return AE_CTRL_TERMINATE;
1632
1633         result = acpi_bus_get_device(handle, &sibling);
1634         if (result)
1635                 return AE_OK;
1636
1637         if (!strcmp(acpi_device_name(sibling), ACPI_VIDEO_BUS_NAME))
1638                         return AE_ALREADY_EXISTS;
1639
1640         return AE_OK;
1641 }
1642
1643 static void acpi_video_dev_register_backlight(struct acpi_video_device *device)
1644 {
1645         if (acpi_video_verify_backlight_support()) {
1646                 struct backlight_properties props;
1647                 struct pci_dev *pdev;
1648                 acpi_handle acpi_parent;
1649                 struct device *parent = NULL;
1650                 int result;
1651                 static int count;
1652                 char *name;
1653
1654                 result = acpi_video_init_brightness(device);
1655                 if (result)
1656                         return;
1657                 name = kasprintf(GFP_KERNEL, "acpi_video%d", count);
1658                 if (!name)
1659                         return;
1660                 count++;
1661
1662                 acpi_get_parent(device->dev->handle, &acpi_parent);
1663
1664                 pdev = acpi_get_pci_dev(acpi_parent);
1665                 if (pdev) {
1666                         parent = &pdev->dev;
1667                         pci_dev_put(pdev);
1668                 }
1669
1670                 memset(&props, 0, sizeof(struct backlight_properties));
1671                 props.type = BACKLIGHT_FIRMWARE;
1672                 props.max_brightness = device->brightness->count - 3;
1673                 device->backlight = backlight_device_register(name,
1674                                                               parent,
1675                                                               device,
1676                                                               &acpi_backlight_ops,
1677                                                               &props);
1678                 kfree(name);
1679                 if (IS_ERR(device->backlight))
1680                         return;
1681
1682                 /*
1683                  * Save current brightness level in case we have to restore it
1684                  * before acpi_video_device_lcd_set_level() is called next time.
1685                  */
1686                 device->backlight->props.brightness =
1687                                 acpi_video_get_brightness(device->backlight);
1688
1689                 device->cooling_dev = thermal_cooling_device_register("LCD",
1690                                         device->dev, &video_cooling_ops);
1691                 if (IS_ERR(device->cooling_dev)) {
1692                         /*
1693                          * Set cooling_dev to NULL so we don't crash trying to
1694                          * free it.
1695                          * Also, why the hell we are returning early and
1696                          * not attempt to register video output if cooling
1697                          * 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
1718 static int acpi_video_bus_register_backlight(struct acpi_video_bus *video)
1719 {
1720         struct acpi_video_device *dev;
1721
1722         mutex_lock(&video->device_list_lock);
1723         list_for_each_entry(dev, &video->video_device_list, entry)
1724                 acpi_video_dev_register_backlight(dev);
1725         mutex_unlock(&video->device_list_lock);
1726
1727         video->pm_nb.notifier_call = acpi_video_resume;
1728         video->pm_nb.priority = 0;
1729         return register_pm_notifier(&video->pm_nb);
1730 }
1731
1732 static void acpi_video_dev_unregister_backlight(struct acpi_video_device *device)
1733 {
1734         if (device->backlight) {
1735                 backlight_device_unregister(device->backlight);
1736                 device->backlight = NULL;
1737         }
1738         if (device->brightness) {
1739                 kfree(device->brightness->levels);
1740                 kfree(device->brightness);
1741                 device->brightness = NULL;
1742         }
1743         if (device->cooling_dev) {
1744                 sysfs_remove_link(&device->dev->dev.kobj, "thermal_cooling");
1745                 sysfs_remove_link(&device->cooling_dev->device.kobj, "device");
1746                 thermal_cooling_device_unregister(device->cooling_dev);
1747                 device->cooling_dev = NULL;
1748         }
1749 }
1750
1751 static int acpi_video_bus_unregister_backlight(struct acpi_video_bus *video)
1752 {
1753         struct acpi_video_device *dev;
1754         int error = unregister_pm_notifier(&video->pm_nb);
1755
1756         mutex_lock(&video->device_list_lock);
1757         list_for_each_entry(dev, &video->video_device_list, entry)
1758                 acpi_video_dev_unregister_backlight(dev);
1759         mutex_unlock(&video->device_list_lock);
1760
1761         return error;
1762 }
1763
1764 static void acpi_video_dev_add_notify_handler(struct acpi_video_device *device)
1765 {
1766         acpi_status status;
1767         struct acpi_device *adev = device->dev;
1768
1769         status = acpi_install_notify_handler(adev->handle, ACPI_DEVICE_NOTIFY,
1770                                              acpi_video_device_notify, device);
1771         if (ACPI_FAILURE(status))
1772                 dev_err(&adev->dev, "Error installing notify handler\n");
1773         else
1774                 device->flags.notify = 1;
1775 }
1776
1777 static int acpi_video_bus_add_notify_handler(struct acpi_video_bus *video)
1778 {
1779         struct input_dev *input;
1780         struct acpi_video_device *dev;
1781         int error;
1782
1783         video->input = input = input_allocate_device();
1784         if (!input) {
1785                 error = -ENOMEM;
1786                 goto out;
1787         }
1788
1789         error = acpi_video_bus_start_devices(video);
1790         if (error)
1791                 goto err_free_input;
1792
1793         snprintf(video->phys, sizeof(video->phys),
1794                         "%s/video/input0", acpi_device_hid(video->device));
1795
1796         input->name = acpi_device_name(video->device);
1797         input->phys = video->phys;
1798         input->id.bustype = BUS_HOST;
1799         input->id.product = 0x06;
1800         input->dev.parent = &video->device->dev;
1801         input->evbit[0] = BIT(EV_KEY);
1802         set_bit(KEY_SWITCHVIDEOMODE, input->keybit);
1803         set_bit(KEY_VIDEO_NEXT, input->keybit);
1804         set_bit(KEY_VIDEO_PREV, input->keybit);
1805         set_bit(KEY_BRIGHTNESS_CYCLE, input->keybit);
1806         set_bit(KEY_BRIGHTNESSUP, input->keybit);
1807         set_bit(KEY_BRIGHTNESSDOWN, input->keybit);
1808         set_bit(KEY_BRIGHTNESS_ZERO, input->keybit);
1809         set_bit(KEY_DISPLAY_OFF, input->keybit);
1810
1811         error = input_register_device(input);
1812         if (error)
1813                 goto err_stop_dev;
1814
1815         mutex_lock(&video->device_list_lock);
1816         list_for_each_entry(dev, &video->video_device_list, entry)
1817                 acpi_video_dev_add_notify_handler(dev);
1818         mutex_unlock(&video->device_list_lock);
1819
1820         return 0;
1821
1822 err_stop_dev:
1823         acpi_video_bus_stop_devices(video);
1824 err_free_input:
1825         input_free_device(input);
1826         video->input = NULL;
1827 out:
1828         return error;
1829 }
1830
1831 static void acpi_video_dev_remove_notify_handler(struct acpi_video_device *dev)
1832 {
1833         if (dev->flags.notify) {
1834                 acpi_remove_notify_handler(dev->dev->handle, ACPI_DEVICE_NOTIFY,
1835                                            acpi_video_device_notify);
1836                 dev->flags.notify = 0;
1837         }
1838 }
1839
1840 static void acpi_video_bus_remove_notify_handler(struct acpi_video_bus *video)
1841 {
1842         struct acpi_video_device *dev;
1843
1844         mutex_lock(&video->device_list_lock);
1845         list_for_each_entry(dev, &video->video_device_list, entry)
1846                 acpi_video_dev_remove_notify_handler(dev);
1847         mutex_unlock(&video->device_list_lock);
1848
1849         acpi_video_bus_stop_devices(video);
1850         input_unregister_device(video->input);
1851         video->input = NULL;
1852 }
1853
1854 static int acpi_video_bus_put_devices(struct acpi_video_bus *video)
1855 {
1856         struct acpi_video_device *dev, *next;
1857
1858         mutex_lock(&video->device_list_lock);
1859         list_for_each_entry_safe(dev, next, &video->video_device_list, entry) {
1860                 list_del(&dev->entry);
1861                 kfree(dev);
1862         }
1863         mutex_unlock(&video->device_list_lock);
1864
1865         return 0;
1866 }
1867
1868 static int instance;
1869
1870 static int acpi_video_bus_add(struct acpi_device *device)
1871 {
1872         struct acpi_video_bus *video;
1873         int error;
1874         acpi_status status;
1875
1876         status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
1877                                 device->parent->handle, 1,
1878                                 acpi_video_bus_match, NULL,
1879                                 device, NULL);
1880         if (status == AE_ALREADY_EXISTS) {
1881                 printk(KERN_WARNING FW_BUG
1882                         "Duplicate ACPI video bus devices for the"
1883                         " same VGA controller, please try module "
1884                         "parameter \"video.allow_duplicates=1\""
1885                         "if the current driver doesn't work.\n");
1886                 if (!allow_duplicates)
1887                         return -ENODEV;
1888         }
1889
1890         video = kzalloc(sizeof(struct acpi_video_bus), GFP_KERNEL);
1891         if (!video)
1892                 return -ENOMEM;
1893
1894         /* a hack to fix the duplicate name "VID" problem on T61 */
1895         if (!strcmp(device->pnp.bus_id, "VID")) {
1896                 if (instance)
1897                         device->pnp.bus_id[3] = '0' + instance;
1898                 instance++;
1899         }
1900         /* a hack to fix the duplicate name "VGA" problem on Pa 3553 */
1901         if (!strcmp(device->pnp.bus_id, "VGA")) {
1902                 if (instance)
1903                         device->pnp.bus_id[3] = '0' + instance;
1904                 instance++;
1905         }
1906
1907         video->device = device;
1908         strcpy(acpi_device_name(device), ACPI_VIDEO_BUS_NAME);
1909         strcpy(acpi_device_class(device), ACPI_VIDEO_CLASS);
1910         device->driver_data = video;
1911
1912         acpi_video_bus_find_cap(video);
1913         error = acpi_video_bus_check(video);
1914         if (error)
1915                 goto err_free_video;
1916
1917         mutex_init(&video->device_list_lock);
1918         INIT_LIST_HEAD(&video->video_device_list);
1919
1920         error = acpi_video_bus_get_devices(video, device);
1921         if (error)
1922                 goto err_put_video;
1923
1924         printk(KERN_INFO PREFIX "%s [%s] (multi-head: %s  rom: %s  post: %s)\n",
1925                ACPI_VIDEO_DEVICE_NAME, acpi_device_bid(device),
1926                video->flags.multihead ? "yes" : "no",
1927                video->flags.rom ? "yes" : "no",
1928                video->flags.post ? "yes" : "no");
1929         mutex_lock(&video_list_lock);
1930         list_add_tail(&video->entry, &video_bus_head);
1931         mutex_unlock(&video_list_lock);
1932
1933         acpi_video_bus_register_backlight(video);
1934         acpi_video_bus_add_notify_handler(video);
1935
1936         return 0;
1937
1938 err_put_video:
1939         acpi_video_bus_put_devices(video);
1940         kfree(video->attached_array);
1941 err_free_video:
1942         kfree(video);
1943         device->driver_data = NULL;
1944
1945         return error;
1946 }
1947
1948 static int acpi_video_bus_remove(struct acpi_device *device)
1949 {
1950         struct acpi_video_bus *video = NULL;
1951
1952
1953         if (!device || !acpi_driver_data(device))
1954                 return -EINVAL;
1955
1956         video = acpi_driver_data(device);
1957
1958         acpi_video_bus_remove_notify_handler(video);
1959         acpi_video_bus_unregister_backlight(video);
1960         acpi_video_bus_put_devices(video);
1961
1962         mutex_lock(&video_list_lock);
1963         list_del(&video->entry);
1964         mutex_unlock(&video_list_lock);
1965
1966         kfree(video->attached_array);
1967         kfree(video);
1968
1969         return 0;
1970 }
1971
1972 static int __init is_i740(struct pci_dev *dev)
1973 {
1974         if (dev->device == 0x00D1)
1975                 return 1;
1976         if (dev->device == 0x7000)
1977                 return 1;
1978         return 0;
1979 }
1980
1981 static int __init intel_opregion_present(void)
1982 {
1983         int opregion = 0;
1984         struct pci_dev *dev = NULL;
1985         u32 address;
1986
1987         for_each_pci_dev(dev) {
1988                 if ((dev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
1989                         continue;
1990                 if (dev->vendor != PCI_VENDOR_ID_INTEL)
1991                         continue;
1992                 /* We don't want to poke around undefined i740 registers */
1993                 if (is_i740(dev))
1994                         continue;
1995                 pci_read_config_dword(dev, 0xfc, &address);
1996                 if (!address)
1997                         continue;
1998                 opregion = 1;
1999         }
2000         return opregion;
2001 }
2002
2003 int acpi_video_register(void)
2004 {
2005         int result = 0;
2006         if (register_count) {
2007                 /*
2008                  * if the function of acpi_video_register is already called,
2009                  * don't register the acpi_vide_bus again and return no error.
2010                  */
2011                 return 0;
2012         }
2013
2014         mutex_init(&video_list_lock);
2015         INIT_LIST_HEAD(&video_bus_head);
2016
2017         result = acpi_bus_register_driver(&acpi_video_bus);
2018         if (result < 0)
2019                 return -ENODEV;
2020
2021         /*
2022          * When the acpi_video_bus is loaded successfully, increase
2023          * the counter reference.
2024          */
2025         register_count = 1;
2026
2027         return 0;
2028 }
2029 EXPORT_SYMBOL(acpi_video_register);
2030
2031 void acpi_video_unregister(void)
2032 {
2033         if (!register_count) {
2034                 /*
2035                  * If the acpi video bus is already unloaded, don't
2036                  * unload it again and return directly.
2037                  */
2038                 return;
2039         }
2040         acpi_bus_unregister_driver(&acpi_video_bus);
2041
2042         register_count = 0;
2043
2044         return;
2045 }
2046 EXPORT_SYMBOL(acpi_video_unregister);
2047
2048 /*
2049  * This is kind of nasty. Hardware using Intel chipsets may require
2050  * the video opregion code to be run first in order to initialise
2051  * state before any ACPI video calls are made. To handle this we defer
2052  * registration of the video class until the opregion code has run.
2053  */
2054
2055 static int __init acpi_video_init(void)
2056 {
2057         dmi_check_system(video_dmi_table);
2058
2059         if (intel_opregion_present())
2060                 return 0;
2061
2062         return acpi_video_register();
2063 }
2064
2065 static void __exit acpi_video_exit(void)
2066 {
2067         acpi_video_unregister();
2068
2069         return;
2070 }
2071
2072 module_init(acpi_video_init);
2073 module_exit(acpi_video_exit);