soc/intel/common: Add helper function to get DP mode

The patch adds helper function to get the DP mode.

TEST=Build the code for Rex

Signed-off-by: Sridhar Siricilla <sridhar.siricilla@intel.com>
Change-Id: I02ed1f818e77c37ead8ce962fa12fddfdc8efeb6
Reviewed-on: https://review.coreboot.org/c/coreboot/+/70507
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>
diff --git a/src/soc/intel/common/block/tcss/tcss.c b/src/soc/intel/common/block/tcss/tcss.c
index 2ae07fd..16669ba 100644
--- a/src/soc/intel/common/block/tcss/tcss.c
+++ b/src/soc/intel/common/block/tcss/tcss.c
@@ -11,6 +11,7 @@
 #include <intelblocks/systemagent.h>
 #include <intelblocks/tcss.h>
 #include <inttypes.h>
+#include <lib.h>
 #include <security/vboot/vboot_common.h>
 #include <soc/pci_devs.h>
 #include <soc/pcr_ids.h>
@@ -204,6 +205,21 @@
 	return send_pmc_req(HPD_REQ, &req, &rsp, PMC_IPC_HPD_REQ_SIZE);
 }
 
+static uint8_t get_dp_mode(uint8_t dp_pin_mode)
+{
+	switch (dp_pin_mode) {
+	case MODE_DP_PIN_A:
+	case MODE_DP_PIN_B:
+	case MODE_DP_PIN_C:
+	case MODE_DP_PIN_D:
+	case MODE_DP_PIN_E:
+	case MODE_DP_PIN_F:
+		return log2(dp_pin_mode) + 1;
+	default:
+		return 0;
+	}
+}
+
 static int send_pmc_dp_mode_request(int port, const struct usbc_mux_info *mux_data,
 					const struct tcss_port_map *port_map)
 {
@@ -227,30 +243,7 @@
 		GET_TCSS_ALT_FIELD(USB3, cmd),
 		GET_TCSS_ALT_FIELD(MODE, cmd));
 
-	switch (mux_data->dp_pin_mode) {
-	case MODE_DP_PIN_A:
-		dp_mode = 1;
-		break;
-	case MODE_DP_PIN_B:
-		dp_mode = 2;
-		break;
-	case MODE_DP_PIN_C:
-		dp_mode = 3;
-		break;
-	case MODE_DP_PIN_D:
-		dp_mode = 4;
-		break;
-	case MODE_DP_PIN_E:
-		dp_mode = 5;
-		break;
-	case MODE_DP_PIN_F:
-		dp_mode = 6;
-		break;
-	default:
-		dp_mode = 0;
-		break;
-	}
-
+	dp_mode = get_dp_mode(mux_data->dp_pin_mode);
 	cmd = tcss_make_alt_mode_cmd_buf_1(
 		mux_data->polarity,
 		mux_data->cable,