drm/amd/display: Add Validate BW for USB4 Links

[WHY]
To validate the BW used for DPIAs per HostRouter

[HOW]
Add the Validate function in C source file
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Mustapha Ghaddar <mghaddar@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_dpia_bw.c

@@ -33,6 +33,10 @@
 #define DC_LOGGER \
 	link->ctx->logger
 
+/* Number of Host Routers per motherboard is 2 */
+#define MAX_HR_NUM			2
+/* Number of DPIA per host router is 2 */
+#define MAX_DPIA_NUM		(MAX_HR_NUM * 2)
 #define Kbps_TO_Gbps (1000 * 1000)
 
 // ------------------------------------------------------------------
@@ -458,3 +462,33 @@ int link_dp_dpia_allocate_usb4_bandwidth_for_stream(struct dc_link *link, int re
 out:
 	return ret;
 }
+bool dpia_validate_usb4_bw(struct dc_link **link, int *bw_needed_per_dpia, uint8_t num_dpias)
+{
+	bool ret = true;
+	int bw_needed_per_hr[MAX_HR_NUM] = { 0, 0 };
+	uint8_t lowest_dpia_index = 0, dpia_index = 0;
+
+	if (!num_dpias || num_dpias > MAX_DPIA_NUM)
+		return ret;
+
+	//Get total Host Router BW & Validate against each Host Router max BW
+	for (uint8_t i = 0; i < num_dpias; ++i) {
+
+		if (!link[i]->dpia_bw_alloc_config.bw_alloc_enabled)
+			continue;
+
+		lowest_dpia_index = get_lowest_dpia_index(link[i]);
+		if (link[i]->link_index < lowest_dpia_index)
+			continue;
+
+		dpia_index = (link[i]->link_index - lowest_dpia_index) / 2;
+		bw_needed_per_hr[dpia_index] += bw_needed_per_dpia[i];
+		if (bw_needed_per_hr[dpia_index] > get_host_router_total_bw(link[i], HOST_ROUTER_BW_ALLOCATED)) {
+
+			ret = false;
+			break;
+		}
+	}
+
+	return ret;
+}

drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_dpia_bw.h

@@ -25,7 +25,9 @@
 
 #ifndef DC_INC_LINK_DP_DPIA_BW_H_
 #define DC_INC_LINK_DP_DPIA_BW_H_
+
 #include "link.h"
+
 /*
  * Host Router BW type
  */
@@ -80,4 +82,16 @@ int dpia_handle_usb4_bandwidth_allocation_for_link(struct dc_link *link, int pea
  */
 void dpia_handle_bw_alloc_response(struct dc_link *link, uint8_t bw, uint8_t result);
 
+/*
+ * Handle the validation of total BW here and confirm that the bw used by each
+ * DPIA doesn't exceed available BW for each host router (HR)
+ *
+ * @link[]: array of link pointer to all possible DPIA links
+ * @bw_needed[]: bw needed for each DPIA link based on timing
+ * @num_dpias: Number of DPIAs for the above 2 arrays. Should always be <= MAX_DPIA_NUM
+ *
+ * return: TRUE if bw used by DPIAs doesn't exceed available BW else return FALSE
+ */
+bool dpia_validate_usb4_bw(struct dc_link **link, int *bw_needed, uint8_t num_dpias);
+
 #endif /* DC_INC_LINK_DP_DPIA_BW_H_ */