[PATCH v5 17/40] drm/i915: Implement HDCP2.2 link integrity check

[Ramalingam C]

Implements the link integrity check once in 500mSec.

Once encryption is enabled, an ongoing Link Integrity Check is
performed by the HDCP Receiver to check that cipher synchronization
is maintained between the HDCP Transmitter and the HDCP Receiver.

On the detection of synchronization lost, the HDCP Receiver must assert
the corresponding bits of the RxStatus register. The Transmitter polls
the RxStatus register and it may initiate re-authentication.

v2:
  Rebased.
v3:
  No Changes.
v4:
  enum check_link_response is used check the link status [Uma]
v5:
  Rebased as part of patch reordering.

Signed-off-by: Ramalingam C <ramalingam.c at intel.com>
---
 drivers/gpu/drm/i915/intel_hdcp.c | 82 +++++++++++++++++++++++++++++++++++++++
 include/drm/drm_hdcp.h            |  8 ++++
 2 files changed, 90 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_hdcp.c b/drivers/gpu/drm/i915/intel_hdcp.c
index cf1c5f20b62e..ec840c1178bb 100644
--- a/drivers/gpu/drm/i915/intel_hdcp.c
+++ b/drivers/gpu/drm/i915/intel_hdcp.c
@@ -25,6 +25,8 @@
 static int intel_hdcp2_init(struct intel_connector *connector);
 static int _intel_hdcp2_enable(struct intel_connector *connector);
 static int _intel_hdcp2_disable(struct intel_connector *connector);
+static void intel_hdcp2_check_work(struct work_struct *work);
+static int intel_hdcp2_check_link(struct intel_connector *connector);
 static
 int intel_hdcp_read_valid_bksv(struct intel_digital_port *intel_dig_port,
 			       const struct intel_hdcp_shim *shim, u8 *bksv);
@@ -841,6 +843,7 @@ int intel_hdcp_init(struct intel_connector *connector,
 	hdcp->hdcp_shim = hdcp_shim;
 	mutex_init(&hdcp->hdcp_mutex);
 	INIT_DELAYED_WORK(&hdcp->hdcp_check_work, intel_hdcp_check_work);
+	INIT_DELAYED_WORK(&hdcp->hdcp2_check_work, intel_hdcp2_check_work);
 	INIT_WORK(&hdcp->hdcp_prop_work, intel_hdcp_prop_work);
 
 	if (hdcp2_supported)
@@ -1709,6 +1712,8 @@ static int _intel_hdcp2_enable(struct intel_connector *connector)
 	hdcp->hdcp2_in_use = true;
 	hdcp->hdcp_value = DRM_MODE_CONTENT_PROTECTION_ENABLED;
 	schedule_work(&hdcp->hdcp_prop_work);
+	schedule_delayed_work(&hdcp->hdcp2_check_work,
+			      DRM_HDCP2_CHECK_PERIOD_MS);
 	return 0;
 }
 
@@ -1914,3 +1919,80 @@ static int intel_hdcp2_init(struct intel_connector *connector)
 exit:
 	return ret;
 }
+
+static int intel_hdcp2_check_link(struct intel_connector *connector)
+{
+	struct intel_digital_port *intel_dig_port = conn_to_dig_port(connector);
+	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
+	struct intel_hdcp *hdcp = &connector->hdcp;
+	enum port port = connector->encoder->port;
+	int ret = 0;
+
+	if (!hdcp->hdcp_shim)
+		return -ENOENT;
+
+	mutex_lock(&hdcp->hdcp_mutex);
+
+	if (hdcp->hdcp_value == DRM_MODE_CONTENT_PROTECTION_UNDESIRED)
+		goto out;
+
+	if (!(I915_READ(HDCP2_STATUS_DDI(port)) & LINK_ENCRYPTION_STATUS)) {
+		DRM_ERROR("HDCP check failed: link is not encrypted, %x\n",
+			  I915_READ(HDCP2_STATUS_DDI(port)));
+		ret = -ENXIO;
+		hdcp->hdcp_value = DRM_MODE_CONTENT_PROTECTION_DESIRED;
+		schedule_work(&hdcp->hdcp_prop_work);
+		goto out;
+	}
+
+	ret = hdcp->hdcp_shim->check_2_2_link(intel_dig_port);
+	if (ret == DRM_HDCP_LINK_PROTECTED) {
+		if (hdcp->hdcp_value != DRM_MODE_CONTENT_PROTECTION_UNDESIRED) {
+			hdcp->hdcp_value = DRM_MODE_CONTENT_PROTECTION_ENABLED;
+			schedule_work(&hdcp->hdcp_prop_work);
+		}
+		goto out;
+	}
+
+	DRM_ERROR("[%s:%d] HDCP2.2 link failed, retrying auth\n",
+		  connector->base.name, connector->base.base.id);
+
+	ret = _intel_hdcp2_disable(connector);
+	if (ret) {
+		DRM_ERROR("[%s:%d] Failed to disable hdcp2.2 (%d)\n",
+			  connector->base.name, connector->base.base.id, ret);
+
+		hdcp->hdcp_value = DRM_MODE_CONTENT_PROTECTION_DESIRED;
+		schedule_work(&hdcp->hdcp_prop_work);
+		goto out;
+	}
+
+	ret = _intel_hdcp2_enable(connector);
+	if (ret) {
+		DRM_ERROR("[%s:%d] Failed to enable hdcp2.2 (%d)\n",
+			  connector->base.name, connector->base.base.id, ret);
+
+		hdcp->hdcp_value = DRM_MODE_CONTENT_PROTECTION_DESIRED;
+		schedule_work(&hdcp->hdcp_prop_work);
+		goto out;
+	}
+
+out:
+	mutex_unlock(&hdcp->hdcp_mutex);
+
+	return ret;
+}
+
+static void intel_hdcp2_check_work(struct work_struct *work)
+{
+	struct intel_hdcp *hdcp = container_of(to_delayed_work(work),
+						struct intel_hdcp,
+						hdcp2_check_work);
+	struct intel_connector *connector = container_of(hdcp,
+						struct intel_connector,
+						hdcp);
+
+	if (!intel_hdcp2_check_link(connector))
+		schedule_delayed_work(&hdcp->hdcp2_check_work,
+				      DRM_HDCP2_CHECK_PERIOD_MS);
+}
diff --git a/include/drm/drm_hdcp.h b/include/drm/drm_hdcp.h
index 0c222b5b685c..76c84d60202f 100644
--- a/include/drm/drm_hdcp.h
+++ b/include/drm/drm_hdcp.h
@@ -11,6 +11,14 @@
 
 /* Period of hdcp checks (to ensure we're still authenticated) */
 #define DRM_HDCP_CHECK_PERIOD_MS		(128 * 16)
+#define DRM_HDCP2_CHECK_PERIOD_MS		500
+
+enum check_link_response {
+	DRM_HDCP_LINK_PROTECTED	= 0,
+	DRM_HDCP_TOPOLOGY_CHANGE,
+	DRM_HDCP_LINK_INTEGRITY_FAILURE,
+	DRM_HDCP_REAUTH_REQUEST
+};
 
 /* Shared lengths/masks between HDMI/DVI/DisplayPort */
 #define DRM_HDCP_AN_LEN				8
-- 
2.7.4