[PATCH v3 3/3] drm/privacy_screen_x86: Add entry for ChromeOS privacy-screen

[Rajat Jain <rajatja@google.com>]

Add a static entry in the x86 table, to detect and wait for
privacy-screen on some ChromeOS platforms.

Please note that this means that if CONFIG_CHROMEOS_PRIVACY_SCREEN is
enabled, and if "GOOG0010" device is found in ACPI, then the i915 probe
shall return EPROBE_DEFER until a platform driver actually registers the
privacy-screen: https://hansdegoede.livejournal.com/25948.html

Signed-off-by: Rajat Jain <rajatja@google.com>
---
v3: * Remove the pr_info() from detect_chromeos_privacy_screen(), instead
      enhance the one already present in drm_privacy_screen_lookup_init()
v2: * Use #if instead of #elif
    * Reorder the patches in the series.
    * Rebased on drm-tip

 drivers/gpu/drm/drm_privacy_screen_x86.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_privacy_screen_x86.c b/drivers/gpu/drm/drm_privacy_screen_x86.c
index a2cafb294ca6..0fdd2b500e6d 100644
--- a/drivers/gpu/drm/drm_privacy_screen_x86.c
+++ b/drivers/gpu/drm/drm_privacy_screen_x86.c
@@ -47,6 +47,16 @@ static bool __init detect_thinkpad_privacy_screen(void)
 }
 #endif
 
+#if IS_ENABLED(CONFIG_CHROMEOS_PRIVACY_SCREEN)
+static bool __init detect_chromeos_privacy_screen(void)
+{
+	if (!acpi_dev_present("GOOG0010", NULL, -1))
+		return false;
+
+	return true;
+}
+#endif
+
 static const struct arch_init_data arch_init_data[] __initconst = {
 #if IS_ENABLED(CONFIG_THINKPAD_ACPI)
 	{
@@ -58,6 +68,16 @@ static const struct arch_init_data arch_init_data[] __initconst = {
 		.detect = detect_thinkpad_privacy_screen,
 	},
 #endif
+#if IS_ENABLED(CONFIG_CHROMEOS_PRIVACY_SCREEN)
+	{
+		.lookup = {
+			.dev_id = NULL,
+			.con_id = NULL,
+			.provider = "privacy_screen-GOOG0010:00",
+		},
+		.detect = detect_chromeos_privacy_screen,
+	},
+#endif
 };
 
 void __init drm_privacy_screen_lookup_init(void)
@@ -68,7 +88,8 @@ void __init drm_privacy_screen_lookup_init(void)
 		if (!arch_init_data[i].detect())
 			continue;
 
-		pr_info("Found '%s' privacy-screen provider\n",
+		pr_info("Found '%s' privacy-screen provider."
+			"Might have to defer probe for it...\n",
 			arch_init_data[i].lookup.provider);
 
 		/* Make a copy because arch_init_data is __initconst */
-- 
2.34.1.307.g9b7440fafd-goog