drm/i915: Implement HDCP for HDMI

This patch adds HDCP support for HDMI connectors by implementing
the intel_hdcp_shim.

Nothing too special, just a bunch of DDC reads/writes.

Changes in v2:
- Rebased on drm-intel-next
Changes in v3:
- Initialize new worker
Changes in v4:
- Remove SKL_ prefix from most register names (Daniel)
- Wrap sanity checks in WARN_ON (Daniel)
- Consolidate the enable/disable functions into one toggle fn
- Use intel_hdcp_init (Daniel)
Changes in v5:
- checkpatch whitespace nits
Changes in v6:
- None

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Ramalingam C <ramalingam.c@intel.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180108195545.218615-9-seanpaul@chromium.org
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 2766b5e..6260a88 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1615,6 +1615,35 @@ void intel_ddi_disable_transcoder_func(struct drm_i915_private *dev_priv,
 	I915_WRITE(reg, val);
 }
 
+int intel_ddi_toggle_hdcp_signalling(struct intel_encoder *intel_encoder,
+				     bool enable)
+{
+	struct drm_device *dev = intel_encoder->base.dev;
+	struct drm_i915_private *dev_priv = to_i915(dev);
+	enum pipe pipe = 0;
+	int ret = 0;
+	uint32_t tmp;
+
+	if (WARN_ON(!intel_display_power_get_if_enabled(dev_priv,
+						intel_encoder->power_domain)))
+		return -ENXIO;
+
+	if (WARN_ON(!intel_encoder->get_hw_state(intel_encoder, &pipe))) {
+		ret = -EIO;
+		goto out;
+	}
+
+	tmp = I915_READ(TRANS_DDI_FUNC_CTL(pipe));
+	if (enable)
+		tmp |= TRANS_DDI_HDCP_SIGNALLING;
+	else
+		tmp &= ~TRANS_DDI_HDCP_SIGNALLING;
+	I915_WRITE(TRANS_DDI_FUNC_CTL(pipe), tmp);
+out:
+	intel_display_power_put(dev_priv, intel_encoder->power_domain);
+	return ret;
+}
+
 bool intel_ddi_connector_get_hw_state(struct intel_connector *intel_connector)
 {
 	struct drm_device *dev = intel_connector->base.dev;