linux/drivers/acpi/video_detect.c
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   1/*
   2 *  Copyright (C) 2008       SuSE Linux Products GmbH
   3 *                           Thomas Renninger <trenn@suse.de>
   4 *
   5 *  May be copied or modified under the terms of the GNU General Public License
   6 *
   7 * video_detect.c:
   8 * Provides acpi_is_video_device() for early scanning of ACPI devices in scan.c
   9 * There a Linux specific (Spec does not provide a HID for video devices) is
  10 * assigned
  11 *
  12 * After PCI devices are glued with ACPI devices
  13 * acpi_get_pci_dev() can be called to identify ACPI graphics
  14 * devices for which a real graphics card is plugged in
  15 *
  16 * Now acpi_video_get_capabilities() can be called to check which
  17 * capabilities the graphics cards plugged in support. The check for general
  18 * video capabilities will be triggered by the first caller of
  19 * acpi_video_get_capabilities(NULL); which will happen when the first
  20 * backlight switching supporting driver calls:
  21 * acpi_video_backlight_support();
  22 *
  23 * Depending on whether ACPI graphics extensions (cmp. ACPI spec Appendix B)
  24 * are available, video.ko should be used to handle the device.
  25 *
  26 * Otherwise vendor specific drivers like thinkpad_acpi, asus-laptop,
  27 * sony_acpi,... can take care about backlight brightness.
  28 *
  29 * If CONFIG_ACPI_VIDEO is neither set as "compiled in" (y) nor as a module (m)
  30 * this file will not be compiled, acpi_video_get_capabilities() and
  31 * acpi_video_backlight_support() will always return 0 and vendor specific
  32 * drivers always can handle backlight.
  33 *
  34 */
  35
  36#include <linux/export.h>
  37#include <linux/acpi.h>
  38#include <linux/dmi.h>
  39#include <linux/pci.h>
  40
  41#define PREFIX "ACPI: "
  42
  43ACPI_MODULE_NAME("video");
  44#define _COMPONENT              ACPI_VIDEO_COMPONENT
  45
  46static long acpi_video_support;
  47static bool acpi_video_caps_checked;
  48
  49static acpi_status
  50acpi_backlight_cap_match(acpi_handle handle, u32 level, void *context,
  51                          void **retyurn_value)
  52{
  53        long *cap = context;
  54        acpi_handle h_dummy;
  55
  56        if (ACPI_SUCCESS(acpi_get_handle(handle, "_BCM", &h_dummy)) &&
  57            ACPI_SUCCESS(acpi_get_handle(handle, "_BCL", &h_dummy))) {
  58                ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found generic backlight "
  59                                  "support\n"));
  60                *cap |= ACPI_VIDEO_BACKLIGHT;
  61                if (ACPI_FAILURE(acpi_get_handle(handle, "_BQC", &h_dummy)))
  62                        printk(KERN_WARNING FW_BUG PREFIX "No _BQC method, "
  63                                "cannot determine initial brightness\n");
  64                /* We have backlight support, no need to scan further */
  65                return AE_CTRL_TERMINATE;
  66        }
  67        return 0;
  68}
  69
  70/* Returns true if the device is a video device which can be handled by
  71 * video.ko.
  72 * The device will get a Linux specific CID added in scan.c to
  73 * identify the device as an ACPI graphics device
  74 * Be aware that the graphics device may not be physically present
  75 * Use acpi_video_get_capabilities() to detect general ACPI video
  76 * capabilities of present cards
  77 */
  78long acpi_is_video_device(struct acpi_device *device)
  79{
  80        acpi_handle h_dummy;
  81        long video_caps = 0;
  82
  83        if (!device)
  84                return 0;
  85
  86        /* Is this device able to support video switching ? */
  87        if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_DOD", &h_dummy)) ||
  88            ACPI_SUCCESS(acpi_get_handle(device->handle, "_DOS", &h_dummy)))
  89                video_caps |= ACPI_VIDEO_OUTPUT_SWITCHING;
  90
  91        /* Is this device able to retrieve a video ROM ? */
  92        if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_ROM", &h_dummy)))
  93                video_caps |= ACPI_VIDEO_ROM_AVAILABLE;
  94
  95        /* Is this device able to configure which video head to be POSTed ? */
  96        if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_VPO", &h_dummy)) &&
  97            ACPI_SUCCESS(acpi_get_handle(device->handle, "_GPD", &h_dummy)) &&
  98            ACPI_SUCCESS(acpi_get_handle(device->handle, "_SPD", &h_dummy)))
  99                video_caps |= ACPI_VIDEO_DEVICE_POSTING;
 100
 101        /* Only check for backlight functionality if one of the above hit. */
 102        if (video_caps)
 103                acpi_walk_namespace(ACPI_TYPE_DEVICE, device->handle,
 104                                    ACPI_UINT32_MAX, acpi_backlight_cap_match, NULL,
 105                                    &video_caps, NULL);
 106
 107        return video_caps;
 108}
 109EXPORT_SYMBOL(acpi_is_video_device);
 110
 111static acpi_status
 112find_video(acpi_handle handle, u32 lvl, void *context, void **rv)
 113{
 114        long *cap = context;
 115        struct pci_dev *dev;
 116        struct acpi_device *acpi_dev;
 117
 118        const struct acpi_device_id video_ids[] = {
 119                {ACPI_VIDEO_HID, 0},
 120                {"", 0},
 121        };
 122        if (acpi_bus_get_device(handle, &acpi_dev))
 123                return AE_OK;
 124
 125        if (!acpi_match_device_ids(acpi_dev, video_ids)) {
 126                dev = acpi_get_pci_dev(handle);
 127                if (!dev)
 128                        return AE_OK;
 129                pci_dev_put(dev);
 130                *cap |= acpi_is_video_device(acpi_dev);
 131        }
 132        return AE_OK;
 133}
 134
 135/* Force to use vendor driver when the ACPI device is known to be
 136 * buggy */
 137static int video_detect_force_vendor(const struct dmi_system_id *d)
 138{
 139        acpi_video_support |= ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
 140        return 0;
 141}
 142
 143static struct dmi_system_id video_detect_dmi_table[] = {
 144        /* On Samsung X360, the BIOS will set a flag (VDRV) if generic
 145         * ACPI backlight device is used. This flag will definitively break
 146         * the backlight interface (even the vendor interface) untill next
 147         * reboot. It's why we should prevent video.ko from being used here
 148         * and we can't rely on a later call to acpi_video_unregister().
 149         */
 150        {
 151         .callback = video_detect_force_vendor,
 152         .ident = "X360",
 153         .matches = {
 154                DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
 155                DMI_MATCH(DMI_PRODUCT_NAME, "X360"),
 156                DMI_MATCH(DMI_BOARD_NAME, "X360"),
 157                },
 158        },
 159        { },
 160};
 161
 162/*
 163 * Returns the video capabilities of a specific ACPI graphics device
 164 *
 165 * if NULL is passed as argument all ACPI devices are enumerated and
 166 * all graphics capabilities of physically present devices are
 167 * summarized and returned. This is cached and done only once.
 168 */
 169long acpi_video_get_capabilities(acpi_handle graphics_handle)
 170{
 171        long caps = 0;
 172        struct acpi_device *tmp_dev;
 173        acpi_status status;
 174
 175        if (acpi_video_caps_checked && graphics_handle == NULL)
 176                return acpi_video_support;
 177
 178        if (!graphics_handle) {
 179                /* Only do the global walk through all graphics devices once */
 180                acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 181                                    ACPI_UINT32_MAX, find_video, NULL,
 182                                    &caps, NULL);
 183                /* There might be boot param flags set already... */
 184                acpi_video_support |= caps;
 185                acpi_video_caps_checked = 1;
 186                /* Add blacklists here. Be careful to use the right *DMI* bits
 187                 * to still be able to override logic via boot params, e.g.:
 188                 *
 189                 *   if (dmi_name_in_vendors("XY")) {
 190                 *      acpi_video_support |=
 191                 *              ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
 192                 *}
 193                 */
 194
 195                dmi_check_system(video_detect_dmi_table);
 196        } else {
 197                status = acpi_bus_get_device(graphics_handle, &tmp_dev);
 198                if (ACPI_FAILURE(status)) {
 199                        ACPI_EXCEPTION((AE_INFO, status, "Invalid device"));
 200                        return 0;
 201                }
 202                acpi_walk_namespace(ACPI_TYPE_DEVICE, graphics_handle,
 203                                    ACPI_UINT32_MAX, find_video, NULL,
 204                                    &caps, NULL);
 205        }
 206        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "We have 0x%lX video support %s %s\n",
 207                          graphics_handle ? caps : acpi_video_support,
 208                          graphics_handle ? "on device " : "in general",
 209                          graphics_handle ? acpi_device_bid(tmp_dev) : ""));
 210        return caps;
 211}
 212EXPORT_SYMBOL(acpi_video_get_capabilities);
 213
 214static void acpi_video_caps_check(void)
 215{
 216        /*
 217         * We must check whether the ACPI graphics device is physically plugged
 218         * in. Therefore this must be called after binding PCI and ACPI devices
 219         */
 220        if (!acpi_video_caps_checked)
 221                acpi_video_get_capabilities(NULL);
 222}
 223
 224/* Promote the vendor interface instead of the generic video module.
 225 * This function allow DMI blacklists to be implemented by externals
 226 * platform drivers instead of putting a big blacklist in video_detect.c
 227 * After calling this function you will probably want to call
 228 * acpi_video_unregister() to make sure the video module is not loaded
 229 */
 230void acpi_video_dmi_promote_vendor(void)
 231{
 232        acpi_video_caps_check();
 233        acpi_video_support |= ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
 234}
 235EXPORT_SYMBOL(acpi_video_dmi_promote_vendor);
 236
 237/* To be called when a driver who previously promoted the vendor
 238 * interface */
 239void acpi_video_dmi_demote_vendor(void)
 240{
 241        acpi_video_caps_check();
 242        acpi_video_support &= ~ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
 243}
 244EXPORT_SYMBOL(acpi_video_dmi_demote_vendor);
 245
 246/* Returns true if video.ko can do backlight switching */
 247int acpi_video_backlight_support(void)
 248{
 249        acpi_video_caps_check();
 250
 251        /* First check for boot param -> highest prio */
 252        if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR)
 253                return 0;
 254        else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO)
 255                return 1;
 256
 257        /* Then check for DMI blacklist -> second highest prio */
 258        if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VENDOR)
 259                return 0;
 260        else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VIDEO)
 261                return 1;
 262
 263        /* Then go the default way */
 264        return acpi_video_support & ACPI_VIDEO_BACKLIGHT;
 265}
 266EXPORT_SYMBOL(acpi_video_backlight_support);
 267
 268/*
 269 * Use acpi_backlight=vendor/video to force that backlight switching
 270 * is processed by vendor specific acpi drivers or video.ko driver.
 271 */
 272static int __init acpi_backlight(char *str)
 273{
 274        if (str == NULL || *str == '\0')
 275                return 1;
 276        else {
 277                if (!strcmp("vendor", str))
 278                        acpi_video_support |=
 279                                ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR;
 280                if (!strcmp("video", str))
 281                        acpi_video_support |=
 282                                ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO;
 283        }
 284        return 1;
 285}
 286__setup("acpi_backlight=", acpi_backlight);
 287
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