drivers/gpu/drm/drm_privacy_screen_x86.c

   1 // SPDX-License-Identifier: MIT
   2 /*
   3  * Copyright (C) 2020 Red Hat, Inc.
   4  *
   5  * Authors:
   6  * Hans de Goede <hdegoede@redhat.com>
   7  */
   8
   9 #include <linux/acpi.h>
  10 #include <drm/drm_privacy_screen_machine.h>
  11
  12 #ifdef CONFIG_X86
  13 static struct drm_privacy_screen_lookup arch_lookup;
  14
  15 struct arch_init_data {
  16         struct drm_privacy_screen_lookup lookup;
  17         bool (*detect)(void);
  18 };
  19
  20 #if IS_ENABLED(CONFIG_THINKPAD_ACPI)
  21 static acpi_status __init acpi_set_handle(acpi_handle handle, u32 level,
  22                                           void *context, void **return_value)
  23 {
  24         *(acpi_handle *)return_value = handle;
  25         return AE_CTRL_TERMINATE;
  26 }
  27
  28 static bool __init detect_thinkpad_privacy_screen(void)
  29 {
  30         union acpi_object obj = { .type = ACPI_TYPE_INTEGER };
  31         struct acpi_object_list args = { .count = 1, .pointer = &obj, };
  32         acpi_handle ec_handle = NULL;
  33         unsigned long long output;
  34         acpi_status status;
  35
  36         if (acpi_disabled)
  37                 return false;
  38
  39         /* Get embedded-controller handle */
  40         status = acpi_get_devices("PNP0C09", acpi_set_handle, NULL, &ec_handle);
  41         if (ACPI_FAILURE(status) || !ec_handle)
  42                 return false;
  43
  44         /* And call the privacy-screen get-status method */
  45         status = acpi_evaluate_integer(ec_handle, "HKEY.GSSS", &args, &output);
  46         if (ACPI_FAILURE(status))
  47                 return false;
  48
  49         return (output & 0x10000) ? true : false;
  50 }
  51 #endif
  52
  53 static const struct arch_init_data arch_init_data[] __initconst = {
  54 #if IS_ENABLED(CONFIG_THINKPAD_ACPI)
  55         {
  56                 .lookup = {
  57                         .dev_id = NULL,
  58                         .con_id = NULL,
  59                         .provider = "privacy_screen-thinkpad_acpi",
  60                 },
  61                 .detect = detect_thinkpad_privacy_screen,
  62         },
  63 #endif
  64 };
  65
  66 void __init drm_privacy_screen_lookup_init(void)
  67 {
  68         int i;
  69
  70         for (i = 0; i < ARRAY_SIZE(arch_init_data); i++) {
  71                 if (!arch_init_data[i].detect())
  72                         continue;
  73
  74                 pr_info("Found '%s' privacy-screen provider\n",
  75                         arch_init_data[i].lookup.provider);
  76
  77                 /* Make a copy because arch_init_data is __initconst */
  78                 arch_lookup = arch_init_data[i].lookup;
  79                 drm_privacy_screen_lookup_add(&arch_lookup);
  80                 break;
  81         }
  82 }
  83
  84 void drm_privacy_screen_lookup_exit(void)
  85 {
  86         if (arch_lookup.provider)
  87                 drm_privacy_screen_lookup_remove(&arch_lookup);
  88 }
  89 #endif /* ifdef CONFIG_X86 */