drm/i915: Add HDCP framework + base implementation

This patch adds the framework required to add HDCP support to intel
connectors. It implements Aksv loading from fuse, and parts 1/2/3
of the HDCP authentication scheme.

Note that without shim implementations, this does not actually implement
HDCP. That will come in subsequent patches.

Changes in v2:
- Don't open code wait_fors (Chris)
- drm_hdcp.c under MIT license (Daniel)
- Move intel_hdcp_disable() call above ddi_disable (Ram)
- Fix // comments (I wore a cone of shame for 12 hours to atone) (Daniel)
- Justify intel_hdcp_shim with comments (Daniel)
- Fixed async locking issues by adding hdcp_mutex (Daniel)
- Don't alter connector_state in enable/disable (Daniel)
Changes in v3:
- Added hdcp_mutex/hdcp_value to make async reasonable
- Added hdcp_prop_work to separate link checking & property setting
- Added new helper for atomic_check state tracking (Daniel)
- Moved enable/disable into atomic_commit with matching helpers
- Moved intel_hdcp_check_link out of all locks when called from dp
- Bumped up ksv_fifo timeout (noticed failure on one of my dongles)
Changes in v4:
- Remove SKL_ prefix from most register names (Daniel)
- Move enable/disable back to modeset path (Daniel)
- s/get_random_long/get_random_u32/ (Daniel)
- Remove mode_config.mutex lock in prop_work (Daniel)
- Add intel_hdcp_init to handle init of conn components (Daniel)
- Actually check return value of attach_property
- Check Bksv is valid before trying to authenticate (Ram)
Changes in v5:
- checkpatch whitespace changes
- s/DRM_MODE_CONTENT_PROTECTION_OFF/DRM_MODE_CONTENT_PROTECTION_UNDESIRED/
- Fix ksv list wait timeout (actually wait 5s)
- Increase the R0 timeout to 300ms (Ram)
Changes in v6:
- SPDX license

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ramalingam C <ramalingm.c@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180108195545.218615-6-seanpaul@chromium.org

1 files changed, 85 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 9848e8e..c59277c 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -301,6 +301,76 @@ struct intel_panel {
 	} backlight;
 };
 
+/*
+ * This structure serves as a translation layer between the generic HDCP code
+ * and the bus-specific code. What that means is that HDCP over HDMI differs
+ * from HDCP over DP, so to account for these differences, we need to
+ * communicate with the receiver through this shim.
+ *
+ * For completeness, the 2 buses differ in the following ways:
+ *	- DP AUX vs. DDC
+ *		HDCP registers on the receiver are set via DP AUX for DP, and
+ *		they are set via DDC for HDMI.
+ *	- Receiver register offsets
+ *		The offsets of the registers are different for DP vs. HDMI
+ *	- Receiver register masks/offsets
+ *		For instance, the ready bit for the KSV fifo is in a different
+ *		place on DP vs HDMI
+ *	- Receiver register names
+ *		Seriously. In the DP spec, the 16-bit register containing
+ *		downstream information is called BINFO, on HDMI it's called
+ *		BSTATUS. To confuse matters further, DP has a BSTATUS register
+ *		with a completely different definition.
+ *	- KSV FIFO
+ *		On HDMI, the ksv fifo is read all at once, whereas on DP it must
+ *		be read 3 keys at a time
+ *	- Aksv output
+ *		Since Aksv is hidden in hardware, there's different procedures
+ *		to send it over DP AUX vs DDC
+ */
+struct intel_hdcp_shim {
+	/* Outputs the transmitter's An and Aksv values to the receiver. */
+	int (*write_an_aksv)(struct intel_digital_port *intel_dig_port, u8 *an);
+
+	/* Reads the receiver's key selection vector */
+	int (*read_bksv)(struct intel_digital_port *intel_dig_port, u8 *bksv);
+
+	/*
+	 * Reads BINFO from DP receivers and BSTATUS from HDMI receivers. The
+	 * definitions are the same in the respective specs, but the names are
+	 * different. Call it BSTATUS since that's the name the HDMI spec
+	 * uses and it was there first.
+	 */
+	int (*read_bstatus)(struct intel_digital_port *intel_dig_port,
+			    u8 *bstatus);
+
+	/* Determines whether a repeater is present downstream */
+	int (*repeater_present)(struct intel_digital_port *intel_dig_port,
+				bool *repeater_present);
+
+	/* Reads the receiver's Ri' value */
+	int (*read_ri_prime)(struct intel_digital_port *intel_dig_port, u8 *ri);
+
+	/* Determines if the receiver's KSV FIFO is ready for consumption */
+	int (*read_ksv_ready)(struct intel_digital_port *intel_dig_port,
+			      bool *ksv_ready);
+
+	/* Reads the ksv fifo for num_downstream devices */
+	int (*read_ksv_fifo)(struct intel_digital_port *intel_dig_port,
+			     int num_downstream, u8 *ksv_fifo);
+
+	/* Reads a 32-bit part of V' from the receiver */
+	int (*read_v_prime_part)(struct intel_digital_port *intel_dig_port,
+				 int i, u32 *part);
+
+	/* Enables HDCP signalling on the port */
+	int (*toggle_signalling)(struct intel_digital_port *intel_dig_port,
+				 bool enable);
+
+	/* Ensures the link is still protected */
+	bool (*check_link)(struct intel_digital_port *intel_dig_port);
+};
+
 struct intel_connector {
 	struct drm_connector base;
 	/*
@@ -332,6 +402,12 @@ struct intel_connector {
 
 	/* Work struct to schedule a uevent on link train failure */
 	struct work_struct modeset_retry_work;
+
+	const struct intel_hdcp_shim *hdcp_shim;
+	struct mutex hdcp_mutex;
+	uint64_t hdcp_value; /* protected by hdcp_mutex */
+	struct delayed_work hdcp_check_work;
+	struct work_struct hdcp_prop_work;
 };
 
 struct intel_digital_connector_state {
@@ -1761,6 +1837,15 @@ static inline void intel_backlight_device_unregister(struct intel_connector *con
 }
 #endif /* CONFIG_BACKLIGHT_CLASS_DEVICE */
 
+/* intel_hdcp.c */
+void intel_hdcp_atomic_check(struct drm_connector *connector,
+			     struct drm_connector_state *old_state,
+			     struct drm_connector_state *new_state);
+int intel_hdcp_init(struct intel_connector *connector,
+		    const struct intel_hdcp_shim *hdcp_shim);
+int intel_hdcp_enable(struct intel_connector *connector);
+int intel_hdcp_disable(struct intel_connector *connector);
+int intel_hdcp_check_link(struct intel_connector *connector);
 
 /* intel_psr.c */
 void intel_psr_enable(struct intel_dp *intel_dp,