tty: xuartps: Initialize ports according to aliases

Register port numbers according to order in DT aliases.
If aliases are not defined, order in DT is used.
If aliases are defined, register port id based
on that.
This patch ensures proper ttyPS0/1 assignment.

[soren]: Combined integer declarations in probe(), removed warning message
if no alias is found.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/xilinx_uartps.c

@@ -1031,17 +1031,21 @@ static struct uart_port xuartps_port[2];
  * xuartps_get_port - Configure the port from the platform device resource
  *			info
  *
+ * @id: Port id
+ *
  * Return: a pointer to a uart_port or NULL for failure
  */
-static struct uart_port *xuartps_get_port(void)
+static struct uart_port *xuartps_get_port(int id)
 {
 	struct uart_port *port;
-	int id;
 
-	/* Find the next unused port */
-	for (id = 0; id < XUARTPS_NR_PORTS; id++)
-		if (xuartps_port[id].mapbase == 0)
-			break;
+	/* Try the given port id if failed use default method */
+	if (xuartps_port[id].mapbase != 0) {
+		/* Find the next unused port */
+		for (id = 0; id < XUARTPS_NR_PORTS; id++)
+			if (xuartps_port[id].mapbase == 0)
+				break;
+	}
 
 	if (id >= XUARTPS_NR_PORTS)
 		return NULL;
@@ -1329,7 +1333,7 @@ static SIMPLE_DEV_PM_OPS(xuartps_dev_pm_ops, xuartps_suspend, xuartps_resume);
  */
 static int xuartps_probe(struct platform_device *pdev)
 {
-	int rc;
+	int rc, id;
 	struct uart_port *port;
 	struct resource *res, *res2;
 	struct xuartps *xuartps_data;
@@ -1380,9 +1384,13 @@ static int xuartps_probe(struct platform_device *pdev)
 				&xuartps_data->clk_rate_change_nb))
 		dev_warn(&pdev->dev, "Unable to register clock notifier.\n");
 #endif
+	/* Look for a serialN alias */
+	id = of_alias_get_id(pdev->dev.of_node, "serial");
+	if (id < 0)
+		id = 0;
 
 	/* Initialize the port structure */
-	port = xuartps_get_port();
+	port = xuartps_get_port(id);
 
 	if (!port) {
 		dev_err(&pdev->dev, "Cannot get uart_port structure\n");