drivers/acpi/video_detect.c

   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_acpi,
  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/acpi.h>
  37 #include <linux/dmi.h>
  38 #include <linux/pci.h>
  39
  40 #define PREFIX "ACPI: "
  41
  42 ACPI_MODULE_NAME("video");
  43 #define _COMPONENT              ACPI_VIDEO_COMPONENT
  44
  45 static long acpi_video_support;
  46 static bool acpi_video_caps_checked;
  47
  48 static acpi_status
  49 acpi_backlight_cap_match(acpi_handle handle, u32 level, void *context,
  50                           void **retyurn_value)
  51 {
  52         long *cap = context;
  53         acpi_handle h_dummy;
  54
  55         if (ACPI_SUCCESS(acpi_get_handle(handle, "_BCM", &h_dummy)) &&
  56             ACPI_SUCCESS(acpi_get_handle(handle, "_BCL", &h_dummy))) {
  57                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found generic backlight "
  58                                   "support\n"));
  59                 *cap |= ACPI_VIDEO_BACKLIGHT;
  60                 if (ACPI_FAILURE(acpi_get_handle(handle, "_BQC", &h_dummy)))
  61                         printk(KERN_WARNING FW_BUG PREFIX "No _BQC method, "
  62                                 "cannot determine initial brightness\n");
  63                 /* We have backlight support, no need to scan further */
  64                 return AE_CTRL_TERMINATE;
  65         }
  66         return 0;
  67 }
  68
  69 /* Returns true if the device is a video device which can be handled by
  70  * video.ko.
  71  * The device will get a Linux specific CID added in scan.c to
  72  * identify the device as an ACPI graphics device
  73  * Be aware that the graphics device may not be physically present
  74  * Use acpi_video_get_capabilities() to detect general ACPI video
  75  * capabilities of present cards
  76  */
  77 long acpi_is_video_device(struct acpi_device *device)
  78 {
  79         acpi_handle h_dummy;
  80         long video_caps = 0;
  81
  82         if (!device)
  83                 return 0;
  84
  85         /* Is this device able to retrieve a video ROM ? */
  86         if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_ROM", &h_dummy)))
  87                 video_caps |= ACPI_VIDEO_ROM_AVAILABLE;
  88
  89         /* Is this device able to configure which video head to be POSTed ? */
  90         if (ACPI_SUCCESS(acpi_get_handle(device->handle, "_VPO", &h_dummy)) &&
  91             ACPI_SUCCESS(acpi_get_handle(device->handle, "_GPD", &h_dummy)) &&
  92             ACPI_SUCCESS(acpi_get_handle(device->handle, "_SPD", &h_dummy)))
  93                 video_caps |= ACPI_VIDEO_DEVICE_POSTING;
  94
  95         /* Only check for backlight functionality if one of the above hit. */
  96         if (video_caps)
  97                 acpi_walk_namespace(ACPI_TYPE_DEVICE, device->handle,
  98                                     ACPI_UINT32_MAX, acpi_backlight_cap_match, NULL,
  99                                     &video_caps, NULL);
 100
 101         return video_caps;
 102 }
 103 EXPORT_SYMBOL(acpi_is_video_device);
 104
 105 static acpi_status
 106 find_video(acpi_handle handle, u32 lvl, void *context, void **rv)
 107 {
 108         long *cap = context;
 109         struct pci_dev *dev;
 110         struct acpi_device *acpi_dev;
 111
 112         const struct acpi_device_id video_ids[] = {
 113                 {ACPI_VIDEO_HID, 0},
 114                 {"", 0},
 115         };
 116         if (acpi_bus_get_device(handle, &acpi_dev))
 117                 return AE_OK;
 118
 119         if (!acpi_match_device_ids(acpi_dev, video_ids)) {
 120                 dev = acpi_get_pci_dev(handle);
 121                 if (!dev)
 122                         return AE_OK;
 123                 pci_dev_put(dev);
 124                 *cap |= acpi_is_video_device(acpi_dev);
 125         }
 126         return AE_OK;
 127 }
 128
 129 /*
 130  * Returns the video capabilities of a specific ACPI graphics device
 131  *
 132  * if NULL is passed as argument all ACPI devices are enumerated and
 133  * all graphics capabilities of physically present devices are
 134  * summarized and returned. This is cached and done only once.
 135  */
 136 long acpi_video_get_capabilities(acpi_handle graphics_handle)
 137 {
 138         long caps = 0;
 139         struct acpi_device *tmp_dev;
 140         acpi_status status;
 141
 142         if (acpi_video_caps_checked && graphics_handle == NULL)
 143                 return acpi_video_support;
 144
 145         if (!graphics_handle) {
 146                 /* Only do the global walk through all graphics devices once */
 147                 acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 148                                     ACPI_UINT32_MAX, find_video, NULL,
 149                                     &caps, NULL);
 150                 /* There might be boot param flags set already... */
 151                 acpi_video_support |= caps;
 152                 acpi_video_caps_checked = 1;
 153                 /* Add blacklists here. Be careful to use the right *DMI* bits
 154                  * to still be able to override logic via boot params, e.g.:
 155                  *
 156                  *   if (dmi_name_in_vendors("XY")) {
 157                  *      acpi_video_support |=
 158                  *              ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
 159                  *}
 160                  */
 161         } else {
 162                 status = acpi_bus_get_device(graphics_handle, &tmp_dev);
 163                 if (ACPI_FAILURE(status)) {
 164                         ACPI_EXCEPTION((AE_INFO, status, "Invalid device"));
 165                         return 0;
 166                 }
 167                 acpi_walk_namespace(ACPI_TYPE_DEVICE, graphics_handle,
 168                                     ACPI_UINT32_MAX, find_video, NULL,
 169                                     &caps, NULL);
 170         }
 171         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "We have 0x%lX video support %s %s\n",
 172                           graphics_handle ? caps : acpi_video_support,
 173                           graphics_handle ? "on device " : "in general",
 174                           graphics_handle ? acpi_device_bid(tmp_dev) : ""));
 175         return caps;
 176 }
 177 EXPORT_SYMBOL(acpi_video_get_capabilities);
 178
 179 /* Returns true if video.ko can do backlight switching */
 180 int acpi_video_backlight_support(void)
 181 {
 182         /*
 183          * We must check whether the ACPI graphics device is physically plugged
 184          * in. Therefore this must be called after binding PCI and ACPI devices
 185          */
 186         if (!acpi_video_caps_checked)
 187                 acpi_video_get_capabilities(NULL);
 188
 189         /* First check for boot param -> highest prio */
 190         if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR)
 191                 return 0;
 192         else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO)
 193                 return 1;
 194
 195         /* Then check for DMI blacklist -> second highest prio */
 196         if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VENDOR)
 197                 return 0;
 198         else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VIDEO)
 199                 return 1;
 200
 201         /* Then go the default way */
 202         return acpi_video_support & ACPI_VIDEO_BACKLIGHT;
 203 }
 204 EXPORT_SYMBOL(acpi_video_backlight_support);
 205
 206 /*
 207  * Use acpi_backlight=vendor/video to force that backlight switching
 208  * is processed by vendor specific acpi drivers or video.ko driver.
 209  */
 210 static int __init acpi_backlight(char *str)
 211 {
 212         if (str == NULL || *str == '\0')
 213                 return 1;
 214         else {
 215                 if (!strcmp("vendor", str))
 216                         acpi_video_support |=
 217                                 ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR;
 218                 if (!strcmp("video", str))
 219                         acpi_video_support |=
 220                                 ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO;
 221         }
 222         return 1;
 223 }
 224 __setup("acpi_backlight=", acpi_backlight);