arm: socfpga: stratix10: Fix mailbox urgent command with urgent register

According to mailbox spec, software should send urgent command with
urgent register instead of COUT location. This patch write urgent
command index to urgent register.

Signed-off-by: Ley Foon Tan <ley.foon.tan@intel.com>

arch/arm/mach-socfpga/mailbox_s10.c

@@ -160,15 +160,15 @@ static __always_inline int mbox_send_cmd_common(u8 id, u32 cmd, u8 is_indirect,
 	u32 buf_len;
 	int ret;
 
-	ret = mbox_prepare_cmd_only(id, cmd, is_indirect, len, arg);
-	if (ret)
-		return ret;
-
 	if (urgent) {
 		/* Read status because it is toggled */
 		status = MBOX_READL(MBOX_STATUS) & MBOX_STATUS_UA_MSK;
-		/* Send command as urgent command */
-		MBOX_WRITEL(1, MBOX_URG);
+		/* Write urgent command to urgent register */
+		MBOX_WRITEL(cmd, MBOX_URG);
+	} else {
+		ret = mbox_prepare_cmd_only(id, cmd, is_indirect, len, arg);
+		if (ret)
+			return ret;
 	}
 
 	/* write doorbell */
@@ -188,8 +188,7 @@ static __always_inline int mbox_send_cmd_common(u8 id, u32 cmd, u8 is_indirect,
 
 		if (urgent) {
 			u32 new_status = MBOX_READL(MBOX_STATUS);
-			/* urgent command doesn't have response */
-			MBOX_WRITEL(0, MBOX_URG);
+
 			/* Urgent ACK is toggled */
 			if ((new_status & MBOX_STATUS_UA_MSK) ^ status)
 				return 0;