[RFC PATCH 6/6] drm/i915: Implement HDCP for DisplayPort

[Sean Paul]

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

Most of this is straightforward read/write from/to DPCD registers. One
thing worth pointing out is the Aksv output bit. It wasn't easily
separable like it's HDMI counterpart, so it's crammed in with the rest
of it.

Signed-off-by: Sean Paul <seanpaul@xxxxxxxxxxxx>
---
 drivers/gpu/drm/i915/intel_dp.c | 243 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 236 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index d11281004109..091c8bcc4645 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -36,7 +36,9 @@
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_crtc_helper.h>
+#include <drm/drm_dp_helper.h>
 #include <drm/drm_edid.h>
+#include <drm/drm_hdcp.h>
 #include "intel_drv.h"
 #include <drm/i915_drm.h>
 #include "i915_drv.h"
@@ -1039,10 +1041,29 @@ static uint32_t skl_get_aux_send_ctl(struct intel_dp *intel_dp,
 	       DP_AUX_CH_CTL_SYNC_PULSE_SKL(32);
 }
 
+static uint32_t intel_dp_get_aux_send_ctl(struct intel_dp *intel_dp,
+				          bool has_aux_irq,
+				          int send_bytes,
+				          uint32_t aux_clock_divider,
+					  bool aksv_write)
+{
+	uint32_t val = 0;
+
+	if (aksv_write) {
+		send_bytes += 5;
+		val |= DP_AUX_CH_CTL_AUX_AKSV_SELECT;
+	}
+
+	return val | intel_dp->get_aux_send_ctl(intel_dp,
+						has_aux_irq,
+						send_bytes,
+						aux_clock_divider);
+}
+
 static int
 intel_dp_aux_ch(struct intel_dp *intel_dp,
 		const uint8_t *send, int send_bytes,
-		uint8_t *recv, int recv_size)
+		uint8_t *recv, int recv_size, bool aksv_write)
 {
 	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
 	struct drm_i915_private *dev_priv =
@@ -1102,10 +1123,11 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
 	}
 
 	while ((aux_clock_divider = intel_dp->get_aux_clock_divider(intel_dp, clock++))) {
-		u32 send_ctl = intel_dp->get_aux_send_ctl(intel_dp,
-							  has_aux_irq,
-							  send_bytes,
-							  aux_clock_divider);
+		u32 send_ctl = intel_dp_get_aux_send_ctl(intel_dp,
+							 has_aux_irq,
+							 send_bytes,
+							 aux_clock_divider,
+							 aksv_write);
 
 		/* Must try at least 3 times according to DP spec */
 		for (try = 0; try < 5; try++) {
@@ -1242,7 +1264,8 @@ intel_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 		if (msg->buffer)
 			memcpy(txbuf + HEADER_SIZE, msg->buffer, msg->size);
 
-		ret = intel_dp_aux_ch(intel_dp, txbuf, txsize, rxbuf, rxsize);
+		ret = intel_dp_aux_ch(intel_dp, txbuf, txsize, rxbuf, rxsize,
+				      false);
 		if (ret > 0) {
 			msg->reply = rxbuf[0] >> 4;
 
@@ -1264,7 +1287,8 @@ intel_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 		if (WARN_ON(rxsize > 20))
 			return -E2BIG;
 
-		ret = intel_dp_aux_ch(intel_dp, txbuf, txsize, rxbuf, rxsize);
+		ret = intel_dp_aux_ch(intel_dp, txbuf, txsize, rxbuf, rxsize,
+				      false);
 		if (ret > 0) {
 			msg->reply = rxbuf[0] >> 4;
 			/*
@@ -4310,6 +4334,8 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
 
 		intel_dp_retrain_link(intel_dp);
 	}
+
+	intel_hdcp_check_link(intel_dp->attached_connector);
 }
 
 /*
@@ -4977,6 +5003,203 @@ void intel_dp_encoder_suspend(struct intel_encoder *intel_encoder)
 	pps_unlock(intel_dp);
 }
 
+static
+int intel_dp_hdcp_write_an_aksv(struct intel_digital_port *intel_dig_port,
+				u8 *an)
+{
+	struct intel_dp *intel_dp = enc_to_intel_dp(&intel_dig_port->base.base);
+	uint8_t txbuf[4], rxbuf[2], reply = 0;
+	ssize_t dpcd_ret;
+	int ret;
+
+	/* Output An first, that's easy */
+	dpcd_ret = drm_dp_dpcd_write(&intel_dig_port->dp.aux, DP_AUX_HDCP_AN,
+				     an, DRM_HDCP_AN_LEN);
+	if (dpcd_ret != DRM_HDCP_AN_LEN) {
+		DRM_ERROR("Failed to write An over DP/AUX (%ld)\n", dpcd_ret);
+		return dpcd_ret >= 0 ? -EIO : dpcd_ret;
+	}
+
+	/*
+	 * Since Aksv is Oh-So-Secret, we can't access it in software. So in
+	 * order to get it on the wire, we need to create the AUX header as if
+	 * we were writing the data, and then tickle the hardware to output the
+	 * data once the header is sent out.
+	 */
+	txbuf[0] = (DP_AUX_NATIVE_WRITE << 4) |
+		   ((DP_AUX_HDCP_AKSV >> 16) & 0xf);
+	txbuf[1] = (DP_AUX_HDCP_AKSV >> 8) & 0xff;
+	txbuf[2] = DP_AUX_HDCP_AKSV & 0xff;
+	txbuf[3] = DRM_HDCP_KSV_LEN - 1;
+
+	ret = intel_dp_aux_ch(intel_dp, txbuf, sizeof(txbuf), rxbuf,
+			      sizeof(rxbuf), true);
+	if (ret < 0) {
+		DRM_ERROR("Write Aksv over DP/AUX failed (%d)\n", ret);
+		return ret;
+	} else if (ret == 0) {
+		DRM_ERROR("Aksv write over DP/AUX was empty\n");
+		return -EIO;
+	}
+
+	reply = (rxbuf[0] >> 4) & DP_AUX_NATIVE_REPLY_MASK;
+	return reply == DP_AUX_NATIVE_REPLY_ACK ? 0 : -EIO;
+}
+
+static int intel_dp_hdcp_read_bksv(struct intel_digital_port *intel_dig_port,
+				   u8 *bksv)
+{
+	ssize_t ret;
+	ret = drm_dp_dpcd_read(&intel_dig_port->dp.aux, DP_AUX_HDCP_BKSV, bksv,
+			       DRM_HDCP_KSV_LEN);
+	if (ret != DRM_HDCP_KSV_LEN) {
+		DRM_ERROR("Read Bksv from DP/AUX failed (%ld)\n", ret);
+		return ret >= 0 ? -EIO : ret;
+	}
+	return 0;
+}
+
+static int intel_dp_hdcp_read_bstatus(struct intel_digital_port *intel_dig_port,
+				      u8 *bstatus)
+{
+	ssize_t ret;
+	/*
+	 * For some reason the HDMI and DP HDCP specs call this register
+	 * definition by different names. In the HDMI spec, it's called BSTATUS,
+	 * but in DP it's called BINFO.
+	 */
+	ret = drm_dp_dpcd_read(&intel_dig_port->dp.aux, DP_AUX_HDCP_BINFO,
+			       bstatus, DRM_HDCP_BSTATUS_LEN);
+	if (ret != DRM_HDCP_BSTATUS_LEN) {
+		DRM_ERROR("Read bstatus from DP/AUX failed (%ld)\n", ret);
+		return ret >= 0 ? -EIO : ret;
+	}
+	return 0;
+}
+
+static
+int intel_dp_hdcp_repeater_present(struct intel_digital_port *intel_dig_port,
+				   bool *repeater_present)
+{
+	ssize_t ret;
+	u8 bcaps;
+	ret = drm_dp_dpcd_read(&intel_dig_port->dp.aux, DP_AUX_HDCP_BCAPS,
+			       &bcaps, 1);
+	if (ret != 1) {
+		DRM_ERROR("Read bcaps from DP/AUX failed (%ld)\n", ret);
+		return ret >= 0 ? -EIO : ret;
+	}
+	*repeater_present = bcaps & DP_BCAPS_REPEATER_PRESENT;
+	return 0;
+}
+
+static
+int intel_dp_hdcp_read_ri_prime(struct intel_digital_port *intel_dig_port,
+				u8 *ri_prime)
+{
+	ssize_t ret;
+	ret = drm_dp_dpcd_read(&intel_dig_port->dp.aux, DP_AUX_HDCP_RI_PRIME,
+			       ri_prime, DRM_HDCP_RI_LEN);
+	if (ret != DRM_HDCP_RI_LEN) {
+		DRM_ERROR("Read Ri' from DP/AUX failed (%ld)\n", ret);
+		return ret >= 0 ? -EIO : ret;
+	}
+	return 0;
+}
+
+static
+int intel_dp_hdcp_read_ksv_ready(struct intel_digital_port *intel_dig_port,
+				 bool *ksv_ready)
+{
+	ssize_t ret;
+	u8 bstatus;
+	ret = drm_dp_dpcd_read(&intel_dig_port->dp.aux, DP_AUX_HDCP_BSTATUS,
+			       &bstatus, 1);
+	if (ret != 1) {
+		DRM_ERROR("Read bstatus from DP/AUX failed (%ld)\n", ret);
+		return ret >= 0 ? -EIO : ret;
+	}
+	*ksv_ready = bstatus & DP_BSTATUS_READY;
+	return 0;
+}
+
+static
+int intel_dp_hdcp_read_ksv_fifo(struct intel_digital_port *intel_dig_port,
+			        int num_downstream, u8 *ksv_fifo)
+{
+	ssize_t ret;
+	int i;
+
+	// KSV list is read via 15 byte window (3 entries @ 5 bytes each)
+	for (i = 0; i < num_downstream; i += 3) {
+		size_t len = min(num_downstream - i, 3) * DRM_HDCP_KSV_LEN;
+		ret = drm_dp_dpcd_read(&intel_dig_port->dp.aux,
+				       DP_AUX_HDCP_KSV_FIFO,
+				       ksv_fifo + i * DRM_HDCP_KSV_LEN,
+				       len);
+		if (ret != len) {
+			DRM_ERROR("Read ksv[%d] from DP/AUX failed (%ld)\n", i,
+				  ret);
+			return ret >= 0 ? -EIO : ret;
+		}
+	}
+	return 0;
+}
+
+static
+int intel_dp_hdcp_read_v_prime_part(struct intel_digital_port *intel_dig_port,
+				    int i, u32 *part)
+{
+	ssize_t ret;
+
+	if (i >= DRM_HDCP_V_PRIME_NUM_PARTS)
+		return -EINVAL;
+
+	ret = drm_dp_dpcd_read(&intel_dig_port->dp.aux,
+			       DP_AUX_HDCP_V_PRIME(i), part,
+			       DRM_HDCP_V_PRIME_PART_LEN);
+	if (ret != DRM_HDCP_V_PRIME_PART_LEN) {
+		DRM_ERROR("Read v'[%d] from DP/AUX failed (%ld)\n", i, ret);
+		return ret >= 0 ? -EIO : ret;
+	}
+	return 0;
+}
+
+static
+int intel_dp_hdcp_toggle_signalling(struct intel_digital_port *intel_dig_port,
+				    bool enable)
+{
+	/* Not used for single stream DisplayPort setups */
+	return 0;
+}
+
+static
+bool intel_dp_hdcp_check_link(struct intel_digital_port *intel_dig_port)
+{
+	ssize_t ret;
+	u8 bstatus;
+	ret = drm_dp_dpcd_read(&intel_dig_port->dp.aux, DP_AUX_HDCP_BSTATUS,
+			       &bstatus, 1);
+	if (ret != 1) {
+		DRM_ERROR("Read bstatus from DP/AUX failed (%ld)\n", ret);
+		return ret >= 0 ? -EIO : ret;
+	}
+	return !(bstatus & DP_BSTATUS_LINK_FAILURE);
+}
+
+static const struct intel_hdcp_shim intel_dp_hdcp_shim = {
+	.write_an_aksv = intel_dp_hdcp_write_an_aksv,
+	.read_bksv = intel_dp_hdcp_read_bksv,
+	.read_bstatus = intel_dp_hdcp_read_bstatus,
+	.repeater_present = intel_dp_hdcp_repeater_present,
+	.read_ri_prime = intel_dp_hdcp_read_ri_prime,
+	.read_ksv_ready = intel_dp_hdcp_read_ksv_ready,
+	.read_ksv_fifo = intel_dp_hdcp_read_ksv_fifo,
+	.read_v_prime_part = intel_dp_hdcp_read_v_prime_part,
+	.toggle_signalling = intel_dp_hdcp_toggle_signalling,
+	.check_link = intel_dp_hdcp_check_link,
+};
+
 static void intel_edp_panel_vdd_sanitize(struct intel_dp *intel_dp)
 {
 	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
@@ -6097,6 +6320,12 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
 
 	intel_dp_add_properties(intel_dp, connector);
 
+	if (INTEL_GEN(dev_priv) >= 9 && !intel_dp_is_edp(intel_dp)) {
+		drm_connector_attach_content_protection_property(connector);
+		intel_connector->hdcp_shim = &intel_dp_hdcp_shim;
+		INIT_DELAYED_WORK(&intel_connector->hdcp_work, intel_hdcp_work);
+	}
+
 	/* For G4X desktop chip, PEG_BAND_GAP_DATA 3:0 must first be written
 	 * 0xd.  Failure to do so will result in spurious interrupts being
 	 * generated on the port when a cable is not attached.
-- 
2.15.0.531.g2ccb3012c9-goog