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/export.h>
  37 #include <linux/acpi.h>
  38 #include <linux/dmi.h>
  39 #include <linux/pci.h>
  40
  41 #define PREFIX "ACPI: "
  42
  43 ACPI_MODULE_NAME("video");
  44 #define _COMPONENT              ACPI_VIDEO_COMPONENT
  45
  46 static long acpi_video_support;
  47 static bool acpi_video_caps_checked;
  48
  49 static acpi_status
  50 acpi_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  */
  78 long 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 }
 109 EXPORT_SYMBOL(acpi_is_video_device);
 110
 111 static acpi_status
 112 find_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 /*
 136  * Returns the video capabilities of a specific ACPI graphics device
 137  *
 138  * if NULL is passed as argument all ACPI devices are enumerated and
 139  * all graphics capabilities of physically present devices are
 140  * summarized and returned. This is cached and done only once.
 141  */
 142 long acpi_video_get_capabilities(acpi_handle graphics_handle)
 143 {
 144         long caps = 0;
 145         struct acpi_device *tmp_dev;
 146         acpi_status status;
 147
 148         if (acpi_video_caps_checked && graphics_handle == NULL)
 149                 return acpi_video_support;
 150
 151         if (!graphics_handle) {
 152                 /* Only do the global walk through all graphics devices once */
 153                 acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
 154                                     ACPI_UINT32_MAX, find_video, NULL,
 155                                     &caps, NULL);
 156                 /* There might be boot param flags set already... */
 157                 acpi_video_support |= caps;
 158                 acpi_video_caps_checked = 1;
 159                 /* Add blacklists here. Be careful to use the right *DMI* bits
 160                  * to still be able to override logic via boot params, e.g.:
 161                  *
 162                  *   if (dmi_name_in_vendors("XY")) {
 163                  *      acpi_video_support |=
 164                  *              ACPI_VIDEO_BACKLIGHT_DMI_VENDOR;
 165                  *}
 166                  */
 167         } else {
 168                 status = acpi_bus_get_device(graphics_handle, &tmp_dev);
 169                 if (ACPI_FAILURE(status)) {
 170                         ACPI_EXCEPTION((AE_INFO, status, "Invalid device"));
 171                         return 0;
 172                 }
 173                 acpi_walk_namespace(ACPI_TYPE_DEVICE, graphics_handle,
 174                                     ACPI_UINT32_MAX, find_video, NULL,
 175                                     &caps, NULL);
 176         }
 177         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "We have 0x%lX video support %s %s\n",
 178                           graphics_handle ? caps : acpi_video_support,
 179                           graphics_handle ? "on device " : "in general",
 180                           graphics_handle ? acpi_device_bid(tmp_dev) : ""));
 181         return caps;
 182 }
 183 EXPORT_SYMBOL(acpi_video_get_capabilities);
 184
 185 /* Returns true if video.ko can do backlight switching */
 186 int acpi_video_backlight_support(void)
 187 {
 188         /*
 189          * We must check whether the ACPI graphics device is physically plugged
 190          * in. Therefore this must be called after binding PCI and ACPI devices
 191          */
 192         if (!acpi_video_caps_checked)
 193                 acpi_video_get_capabilities(NULL);
 194
 195         /* First check for boot param -> highest prio */
 196         if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR)
 197                 return 0;
 198         else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO)
 199                 return 1;
 200
 201         /* Then check for DMI blacklist -> second highest prio */
 202         if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VENDOR)
 203                 return 0;
 204         else if (acpi_video_support & ACPI_VIDEO_BACKLIGHT_DMI_VIDEO)
 205                 return 1;
 206
 207         /* Then go the default way */
 208         return acpi_video_support & ACPI_VIDEO_BACKLIGHT;
 209 }
 210 EXPORT_SYMBOL(acpi_video_backlight_support);
 211
 212 /*
 213  * Use acpi_backlight=vendor/video to force that backlight switching
 214  * is processed by vendor specific acpi drivers or video.ko driver.
 215  */
 216 static int __init acpi_backlight(char *str)
 217 {
 218         if (str == NULL || *str == '\0')
 219                 return 1;
 220         else {
 221                 if (!strcmp("vendor", str))
 222                         acpi_video_support |=
 223                                 ACPI_VIDEO_BACKLIGHT_FORCE_VENDOR;
 224                 if (!strcmp("video", str))
 225                         acpi_video_support |=
 226                                 ACPI_VIDEO_BACKLIGHT_FORCE_VIDEO;
 227         }
 228         return 1;
 229 }
 230 __setup("acpi_backlight=", acpi_backlight);