drm/amd/display: Read USB4 DP tunneling data from DPCD.

[Why]
We requires information from DPCD in order to identify USB4 DP
tunneling targets.

[How]
Add USB4 DP tunneling fields to DPCD struct and populate these fields
during sink detection.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Wayne Lin <Wayne.Lin@amd.com>
Acked-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/core/dc_link_dpia.c

@@ -34,14 +34,40 @@
 #include "inc/link_dpcd.h"
 #include "dm_helpers.h"
 #include "dmub/inc/dmub_cmd.h"
+#include "inc/link_dpcd.h"
 
 #define DC_LOGGER \
 	link->ctx->logger
 
 enum dc_status dpcd_get_tunneling_device_data(struct dc_link *link)
 {
-	/** @todo Read corresponding DPCD region and update link caps. */
-	return DC_OK;
+	enum dc_status status = DC_OK;
+	uint8_t dpcd_dp_tun_data[3] = {0};
+	uint8_t dpcd_topology_data[DPCD_USB4_TOPOLOGY_ID_LEN] = {0};
+	uint8_t i = 0;
+
+	status = core_link_read_dpcd(link,
+			DP_TUNNELING_CAPABILITIES_SUPPORT,
+			dpcd_dp_tun_data,
+			sizeof(dpcd_dp_tun_data));
+
+	status = core_link_read_dpcd(link,
+			DP_USB4_ROUTER_TOPOLOGY_ID,
+			dpcd_topology_data,
+			sizeof(dpcd_topology_data));
+
+	link->dpcd_caps.usb4_dp_tun_info.dp_tun_cap.raw =
+			dpcd_dp_tun_data[DP_TUNNELING_CAPABILITIES_SUPPORT -
+					 DP_TUNNELING_CAPABILITIES_SUPPORT];
+	link->dpcd_caps.usb4_dp_tun_info.dpia_info.raw =
+			dpcd_dp_tun_data[DP_IN_ADAPTER_INFO - DP_TUNNELING_CAPABILITIES_SUPPORT];
+	link->dpcd_caps.usb4_dp_tun_info.usb4_driver_id =
+			dpcd_dp_tun_data[DP_USB4_DRIVER_ID - DP_TUNNELING_CAPABILITIES_SUPPORT];
+
+	for (i = 0; i < DPCD_USB4_TOPOLOGY_ID_LEN; i++)
+		link->dpcd_caps.usb4_dp_tun_info.usb4_topology_id[i] = dpcd_topology_data[i];
+
+	return status;
 }
 
 /* Configure link as prescribed in link_setting; set LTTPR mode; and

drivers/gpu/drm/amd/display/dc/dc.h

@@ -1186,6 +1186,7 @@ struct dpcd_caps {
 	struct dpcd_dsc_capabilities dsc_caps;
 	struct dc_lttpr_caps lttpr_caps;
 	struct psr_caps psr_caps;
+	struct dpcd_usb4_dp_tunneling_info usb4_dp_tun_info;
 
 #if defined(CONFIG_DRM_AMD_DC_DCN)
 	union dp_128b_132b_supported_link_rates dp_128b_132b_supported_link_rates;

drivers/gpu/drm/amd/display/dc/dc_dp_types.h

@@ -859,6 +859,37 @@ struct psr_caps {
 	bool psr_exit_link_training_required;
 };
 
+/* Length of router topology ID read from DPCD in bytes. */
+#define DPCD_USB4_TOPOLOGY_ID_LEN 5
+
+/* DPCD[0xE000D] DP_TUNNELING_CAPABILITIES SUPPORT register. */
+union dp_tun_cap_support {
+	struct {
+		uint8_t dp_tunneling :1;
+		uint8_t rsvd :5;
+		uint8_t panel_replay_tun_opt :1;
+		uint8_t dpia_bw_alloc :1;
+	} bits;
+	uint8_t raw;
+};
+
+/* DPCD[0xE000E] DP_IN_ADAPTER_INFO register. */
+union dpia_info {
+	struct {
+		uint8_t dpia_num :5;
+		uint8_t rsvd :3;
+	} bits;
+	uint8_t raw;
+};
+
+/* DP Tunneling over USB4 */
+struct dpcd_usb4_dp_tunneling_info {
+	union dp_tun_cap_support dp_tun_cap;
+	union dpia_info dpia_info;
+	uint8_t usb4_driver_id;
+	uint8_t usb4_topology_id[DPCD_USB4_TOPOLOGY_ID_LEN];
+};
+
 #if defined(CONFIG_DRM_AMD_DC_DCN)
 #ifndef DP_MAIN_LINK_CHANNEL_CODING_CAP
 #define DP_MAIN_LINK_CHANNEL_CODING_CAP			0x006

drivers/gpu/drm/amd/display/dc/inc/dc_link_dpia.h

@@ -35,6 +35,13 @@ struct dc_link_settings;
 /* The approximate time (us) it takes to transmit 9 USB4 DP clock sync packets. */
 #define DPIA_CLK_SYNC_DELAY 16000
 
+/** @note Can remove once DP tunneling registers in upstream include/drm/drm_dp_helper.h */
+/* DPCD DP Tunneling over USB4 */
+#define DP_TUNNELING_CAPABILITIES_SUPPORT 0xe000d
+#define DP_IN_ADAPTER_INFO                0xe000e
+#define DP_USB4_DRIVER_ID                 0xe000f
+#define DP_USB4_ROUTER_TOPOLOGY_ID        0xe001b
+
 /* SET_CONFIG message types sent by driver. */
 enum dpia_set_config_type {
 	DPIA_SET_CFG_SET_LINK = 0x01,