drm/mst: Add support for QUERY_STREAM_ENCRYPTION_STATUS MST sideband message

Used to query whether an MST stream is encrypted or not.

Cc: Lyude Paul <lyude@redhat.com>
Reviewed-by: Anshuman Gupta <anshuman.gupta@intel.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>

Link: https://patchwork.freedesktop.org/patch/msgid/20200218220242.107265-14-sean@poorly.run #v4
Link: https://patchwork.freedesktop.org/patch/msgid/20200305201236.152307-15-sean@poorly.run #v5
Link: https://patchwork.freedesktop.org/patch/msgid/20200429195502.39919-15-sean@poorly.run #v6
Link: https://patchwork.freedesktop.org/patch/msgid/20200623155907.22961-16-sean@poorly.run #v7
Link: https://patchwork.freedesktop.org/patch/msgid/20200818153910.27894-16-sean@poorly.run #v8

Changes in v4:
-Added to the set
Changes in v5:
-None
Changes in v6:
-Use FIELD_PREP to generate request buffer bitfields (Lyude)
-Add mst selftest and dump/decode_sideband_req for QSES (Lyude)
Changes in v7:
-None
Changes in v8:
-Reverse the parsing on the hdcp_*x_device_present bits and leave
 breadcrumb in case this is incorrect (Anshuman)
Changes in v8.5:
-s/DRM_DEBUG_KMS/drm_dbg_kms/ (Lyude)

Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200819143133.46232-1-sean@poorly.run

2 files changed, 167 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index b23cb2fec3f3..b273d9ba7cbf 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -20,11 +20,13 @@
  * OF THIS SOFTWARE.
  */
 
+#include <linux/bitfield.h>
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/random.h>
 #include <linux/sched.h>
 #include <linux/seq_file.h>
 #include <linux/iopoll.h>
@@ -423,6 +425,22 @@ drm_dp_encode_sideband_req(const struct drm_dp_sideband_msg_req_body *req,
 		memcpy(&buf[idx], req->u.i2c_write.bytes, req->u.i2c_write.num_bytes);
 		idx += req->u.i2c_write.num_bytes;
 		break;
+	case DP_QUERY_STREAM_ENC_STATUS: {
+		const struct drm_dp_query_stream_enc_status *msg;
+
+		msg = &req->u.enc_status;
+		buf[idx] = msg->stream_id;
+		idx++;
+		memcpy(&buf[idx], msg->client_id, sizeof(msg->client_id));
+		idx += sizeof(msg->client_id);
+		buf[idx] = 0;
+		buf[idx] |= FIELD_PREP(GENMASK(1, 0), msg->stream_event);
+		buf[idx] |= msg->valid_stream_event ? BIT(2) : 0;
+		buf[idx] |= FIELD_PREP(GENMASK(4, 3), msg->stream_behavior);
+		buf[idx] |= msg->valid_stream_behavior ? BIT(5) : 0;
+		idx++;
+		}
+		break;
 	}
 	raw->cur_len = idx;
 }
@@ -551,6 +569,20 @@ drm_dp_decode_sideband_req(const struct drm_dp_sideband_msg_tx *raw,
 				return -ENOMEM;
 		}
 		break;
+	case DP_QUERY_STREAM_ENC_STATUS:
+		req->u.enc_status.stream_id = buf[idx++];
+		for (i = 0; i < sizeof(req->u.enc_status.client_id); i++)
+			req->u.enc_status.client_id[i] = buf[idx++];
+
+		req->u.enc_status.stream_event = FIELD_GET(GENMASK(1, 0),
+							   buf[idx]);
+		req->u.enc_status.valid_stream_event = FIELD_GET(BIT(2),
+								 buf[idx]);
+		req->u.enc_status.stream_behavior = FIELD_GET(GENMASK(4, 3),
+							      buf[idx]);
+		req->u.enc_status.valid_stream_behavior = FIELD_GET(BIT(5),
+								    buf[idx]);
+		break;
 	}
 
 	return 0;
@@ -629,6 +661,16 @@ drm_dp_dump_sideband_msg_req_body(const struct drm_dp_sideband_msg_req_body *req
 		  req->u.i2c_write.num_bytes, req->u.i2c_write.num_bytes,
 		  req->u.i2c_write.bytes);
 		break;
+	case DP_QUERY_STREAM_ENC_STATUS:
+		P("stream_id=%u client_id=%*ph stream_event=%x "
+		  "valid_event=%d stream_behavior=%x valid_behavior=%d",
+		  req->u.enc_status.stream_id,
+		  (int)ARRAY_SIZE(req->u.enc_status.client_id),
+		  req->u.enc_status.client_id, req->u.enc_status.stream_event,
+		  req->u.enc_status.valid_stream_event,
+		  req->u.enc_status.stream_behavior,
+		  req->u.enc_status.valid_stream_behavior);
+		break;
 	default:
 		P("???\n");
 		break;
@@ -936,6 +978,42 @@ static bool drm_dp_sideband_parse_power_updown_phy_ack(struct drm_dp_sideband_ms
 	return true;
 }
 
+static bool
+drm_dp_sideband_parse_query_stream_enc_status(
+				struct drm_dp_sideband_msg_rx *raw,
+				struct drm_dp_sideband_msg_reply_body *repmsg)
+{
+	struct drm_dp_query_stream_enc_status_ack_reply *reply;
+
+	reply = &repmsg->u.enc_status;
+
+	reply->stream_id = raw->msg[3];
+
+	reply->reply_signed = raw->msg[2] & BIT(0);
+
+	/*
+	 * NOTE: It's my impression from reading the spec that the below parsing
+	 * is correct. However I noticed while testing with an HDCP 1.4 display
+	 * through an HDCP 2.2 hub that only bit 3 was set. In that case, I
+	 * would expect both bits to be set. So keep the parsing following the
+	 * spec, but beware reality might not match the spec (at least for some
+	 * configurations).
+	 */
+	reply->hdcp_1x_device_present = raw->msg[2] & BIT(4);
+	reply->hdcp_2x_device_present = raw->msg[2] & BIT(3);
+
+	reply->query_capable_device_present = raw->msg[2] & BIT(5);
+	reply->legacy_device_present = raw->msg[2] & BIT(6);
+	reply->unauthorizable_device_present = raw->msg[2] & BIT(7);
+
+	reply->auth_completed = !!(raw->msg[1] & BIT(3));
+	reply->encryption_enabled = !!(raw->msg[1] & BIT(4));
+	reply->repeater_present = !!(raw->msg[1] & BIT(5));
+	reply->state = (raw->msg[1] & GENMASK(7, 6)) >> 6;
+
+	return true;
+}
+
 static bool drm_dp_sideband_parse_reply(struct drm_dp_sideband_msg_rx *raw,
 					struct drm_dp_sideband_msg_reply_body *msg)
 {
@@ -970,6 +1048,8 @@ static bool drm_dp_sideband_parse_reply(struct drm_dp_sideband_msg_rx *raw,
 		return drm_dp_sideband_parse_power_updown_phy_ack(raw, msg);
 	case DP_CLEAR_PAYLOAD_ID_TABLE:
 		return true; /* since there's nothing to parse */
+	case DP_QUERY_STREAM_ENC_STATUS:
+		return drm_dp_sideband_parse_query_stream_enc_status(raw, msg);
 	default:
 		DRM_ERROR("Got unknown reply 0x%02x (%s)\n", msg->req_type,
 			  drm_dp_mst_req_type_str(msg->req_type));
@@ -1121,6 +1201,25 @@ static void build_power_updown_phy(struct drm_dp_sideband_msg_tx *msg,
 	msg->path_msg = true;
 }
 
+static int
+build_query_stream_enc_status(struct drm_dp_sideband_msg_tx *msg, u8 stream_id,
+			      u8 *q_id)
+{
+	struct drm_dp_sideband_msg_req_body req;
+
+	req.req_type = DP_QUERY_STREAM_ENC_STATUS;
+	req.u.enc_status.stream_id = stream_id;
+	memcpy(req.u.enc_status.client_id, q_id,
+	       sizeof(req.u.enc_status.client_id));
+	req.u.enc_status.stream_event = 0;
+	req.u.enc_status.valid_stream_event = false;
+	req.u.enc_status.stream_behavior = 0;
+	req.u.enc_status.valid_stream_behavior = false;
+
+	drm_dp_encode_sideband_req(&req, msg);
+	return 0;
+}
+
 static int drm_dp_mst_assign_payload_id(struct drm_dp_mst_topology_mgr *mgr,
 					struct drm_dp_vcpi *vcpi)
 {
@@ -3153,6 +3252,57 @@ int drm_dp_send_power_updown_phy(struct drm_dp_mst_topology_mgr *mgr,
 }
 EXPORT_SYMBOL(drm_dp_send_power_updown_phy);
 
+int drm_dp_send_query_stream_enc_status(struct drm_dp_mst_topology_mgr *mgr,
+		struct drm_dp_mst_port *port,
+		struct drm_dp_query_stream_enc_status_ack_reply *status)
+{
+	struct drm_dp_sideband_msg_tx *txmsg;
+	u8 nonce[7];
+	int len, ret;
+
+	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
+	if (!txmsg)
+		return -ENOMEM;
+
+	port = drm_dp_mst_topology_get_port_validated(mgr, port);
+	if (!port) {
+		ret = -EINVAL;
+		goto out_get_port;
+	}
+
+	get_random_bytes(nonce, sizeof(nonce));
+
+	/*
+	 * "Source device targets the QUERY_STREAM_ENCRYPTION_STATUS message
+	 *  transaction at the MST Branch device directly connected to the
+	 *  Source"
+	 */
+	txmsg->dst = mgr->mst_primary;
+
+	len = build_query_stream_enc_status(txmsg, port->vcpi.vcpi, nonce);
+
+	drm_dp_queue_down_tx(mgr, txmsg);
+
+	ret = drm_dp_mst_wait_tx_reply(mgr->mst_primary, txmsg);
+	if (ret < 0) {
+		goto out;
+	} else if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
+		drm_dbg_kms(mgr->dev, "query encryption status nak received\n");
+		ret = -ENXIO;
+		goto out;
+	}
+
+	ret = 0;
+	memcpy(status, &txmsg->reply.u.enc_status, sizeof(*status));
+
+out:
+	drm_dp_mst_topology_put_port(port);
+out_get_port:
+	kfree(txmsg);
+	return ret;
+}
+EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
+
 static int drm_dp_create_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
 				       int id,
 				       struct drm_dp_payload *payload)
diff --git a/drivers/gpu/drm/selftests/test-drm_dp_mst_helper.c b/drivers/gpu/drm/selftests/test-drm_dp_mst_helper.c
index bd990d178765..1d696ec001cf 100644
--- a/drivers/gpu/drm/selftests/test-drm_dp_mst_helper.c
+++ b/drivers/gpu/drm/selftests/test-drm_dp_mst_helper.c
@@ -5,6 +5,8 @@
 
 #define PREFIX_STR "[drm_dp_mst_helper]"
 
+#include <linux/random.h>
+
 #include <drm/drm_dp_mst_helper.h>
 #include <drm/drm_print.h>
 
@@ -237,6 +239,21 @@ int igt_dp_mst_sideband_msg_req_decode(void *unused)
 	in.u.i2c_write.bytes = data;
 	DO_TEST();
 
+	in.req_type = DP_QUERY_STREAM_ENC_STATUS;
+	in.u.enc_status.stream_id = 1;
+	DO_TEST();
+	get_random_bytes(in.u.enc_status.client_id,
+			 sizeof(in.u.enc_status.client_id));
+	DO_TEST();
+	in.u.enc_status.stream_event = 3;
+	DO_TEST();
+	in.u.enc_status.valid_stream_event = 0;
+	DO_TEST();
+	in.u.enc_status.stream_behavior = 3;
+	DO_TEST();
+	in.u.enc_status.valid_stream_behavior = 1;
+	DO_TEST();
+
 #undef DO_TEST
 	return 0;
 }