[PATCH v2 8/8] 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.

Changes in v2:
- Moved intel_hdcp_check_link out of intel_dp_check_link and only call
  it on short pulse. Since intel_hdcp_check_link does its own locking,
  this ensures we don't deadlock when intel_dp_check_link is called
  holding connection_mutex.
- Rebased on drm-intel-next

Signed-off-by: Sean Paul <seanpaul@xxxxxxxxxxxx>
---
 drivers/gpu/drm/i915/intel_dp.c | 245 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 238 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index bc61f38b131d..b237cac822fa 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"
@@ -1025,10 +1027,29 @@ 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 =
@@ -1088,10 +1109,11 @@ 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++) {
@@ -1228,7 +1250,8 @@ 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;
 
@@ -1250,7 +1273,8 @@ 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;
 			/*
@@ -4373,6 +4397,9 @@ intel_dp_short_pulse(struct intel_dp *intel_dp)
 		drm_kms_helper_hotplug_event(&dev_priv->drm);
 	}
 
+	/* Short pulse can signify loss of hdcp authentication */
+	intel_hdcp_check_link(intel_dp->attached_connector);
+
 	return true;
 }
 
@@ -4963,6 +4990,203 @@ 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 drm_i915_private *dev_priv = to_i915(intel_dp_to_dev(intel_dp));
@@ -6066,6 +6290,13 @@ 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;
+		mutex_init(&intel_connector->hdcp_mutex);
+		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