drm: Add Content Protection property

This patch adds a new optional connector property to allow userspace to enable
protection over the content it is displaying. This will typically be implemented
by the driver using HDCP.

The property is a tri-state with the following values:
- OFF: Self explanatory, no content protection
- DESIRED: Userspace requests that the driver enable protection
- ENABLED: Once the driver has authenticated the link, it sets this value

The driver is responsible for downgrading ENABLED to DESIRED if the link becomes
unprotected. The driver should also maintain the desiredness of protection
across hotplug/dpms/suspend.

If this looks familiar, I posted [1] this 3 years ago. We have been using this
in ChromeOS across exynos, mediatek, and rockchip over that time.

Changes in v2:
 - Pimp kerneldoc for content_protection_property (Daniel)
 - Drop sysfs attribute
Changes in v3:
 - None
Changes in v4:
- Changed kerneldoc to recommend userspace polling (Daniel)
- Changed kerneldoc to briefly describe how to attach the property (Daniel)
Changes in v5:
- checkpatch whitespace noise
- Change DRM_MODE_CONTENT_PROTECTION_OFF to DRM_MODE_CONTENT_PROTECTION_UNDESIRED
Changes in v6:
- None

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Sean Paul <seanpaul@chromium.org>

[1] https://lists.freedesktop.org/archives/dri-devel/2014-December/073336.html
Link: https://patchwork.freedesktop.org/patch/msgid/20180108195545.218615-4-seanpaul@chromium.org

1 files changed, 15 insertions, 0 deletions

diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index fb563a1b0448..3e9e4b632bc7 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -380,6 +380,11 @@ struct drm_connector_state {
 	 */
 	struct drm_property_blob *hdr_source_metadata_blob_ptr;
 	bool hdr_metadata_changed : 1;
+	/**
+	 * @content_protection: Connector property to request content
+	 * protection. This is most commonly used for HDCP.
+	 */
+	unsigned int content_protection;
 };
 
 /**
@@ -728,6 +733,7 @@ struct drm_cmdline_mode {
  * @tile_h_size: horizontal size of this tile.
  * @tile_v_size: vertical size of this tile.
  * @scaling_mode_property:  Optional atomic property to control the upscaling.
+ * @content_protection_property: Optional property to control content protection
  *
  * Each connector may be connected to one or more CRTCs, or may be clonable by
  * another connector if they can share a CRTC.  Each connector also has a specific
@@ -819,6 +825,12 @@ struct drm_connector {
 	struct drm_property *scaling_mode_property;
 
 	/**
+	 * @content_protection_property: DRM ENUM property for content
+	 * protection
+	 */
+	struct drm_property *content_protection_property;
+
+	/**
 	 * @path_blob_ptr:
 	 *
 	 * DRM blob property data for the DP MST path property.
@@ -1015,6 +1027,7 @@ const char *drm_get_dvi_i_subconnector_name(int val);
 const char *drm_get_dvi_i_select_name(int val);
 const char *drm_get_tv_subconnector_name(int val);
 const char *drm_get_tv_select_name(int val);
+const char *drm_get_content_protection_name(int val);
 
 int drm_mode_create_dvi_i_properties(struct drm_device *dev);
 int drm_mode_create_tv_properties(struct drm_device *dev,
@@ -1023,6 +1036,8 @@ int drm_mode_create_tv_properties(struct drm_device *dev,
 int drm_mode_create_scaling_mode_property(struct drm_device *dev);
 int drm_connector_attach_scaling_mode_property(struct drm_connector *connector,
 					       u32 scaling_mode_mask);
+int drm_connector_attach_content_protection_property(
+		struct drm_connector *connector);
 int drm_mode_create_aspect_ratio_property(struct drm_device *dev);
 int drm_mode_create_suggested_offset_properties(struct drm_device *dev);