serial: xilinx: Use platform_get_irq to get irq description structure

commit 5c90c07b upstream.

For systems with CONFIG_SERIAL_OF_PLATFORM=y and device_type =
"serial"; property in DT of_serial.c driver maps and unmaps IRQ (because
driver probe fails). Then a driver is called but irq mapping is not
created that's why driver is failing again in again on request_irq().
Based on this use platform_get_irq() instead of platform_get_resource()
which is doing irq_desc allocation and driver itself can request IRQ.

Fix both xilinx serial drivers in the tree.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2:
 - Adjust context
 - Return directly on failure in xuartps_probe()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/tty/serial/uartlite.c

@@ -573,7 +573,8 @@ MODULE_DEVICE_TABLE(of, ulite_of_match);
 
 static int __devinit ulite_probe(struct platform_device *pdev)
 {
-	struct resource *res, *res2;
+	struct resource *res;
+	int irq;
 	int id = pdev->id;
 #ifdef CONFIG_OF
 	const __be32 *prop;
@@ -587,11 +588,11 @@ static int __devinit ulite_probe(struct platform_device *pdev)
 	if (!res)
 		return -ENODEV;
 
-	res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
-	if (!res2)
-		return -ENODEV;
+	irq = platform_get_irq(pdev, 0);
+	if (irq <= 0)
+		return -ENXIO;
 
-	return ulite_assign(&pdev->dev, id, res->start, res2->start);
+	return ulite_assign(&pdev->dev, id, res->start, irq);
 }
 
 static int __devexit ulite_remove(struct platform_device *pdev)

drivers/tty/serial/xilinx_uartps.c

@@ -941,9 +941,9 @@ static struct uart_driver xuartps_uart_driver = {
  **/
 static int __devinit xuartps_probe(struct platform_device *pdev)
 {
-	int rc;
+	int rc, irq;
 	struct uart_port *port;
-	struct resource *res, *res2;
+	struct resource *res;
 	int clk = 0;
 
 #ifdef CONFIG_OF
@@ -964,9 +964,9 @@ static int __devinit xuartps_probe(struct platform_device *pdev)
 	if (!res)
 		return -ENODEV;
 
-	res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
-	if (!res2)
-		return -ENODEV;
+	irq = platform_get_irq(pdev, 0);
+	if (irq <= 0)
+		return -ENXIO;
 
 	/* Initialize the port structure */
 	port = xuartps_get_port();
@@ -980,7 +980,7 @@ static int __devinit xuartps_probe(struct platform_device *pdev)
 		 * and triggers invocation of the config_port() entry point.
 		 */
 		port->mapbase = res->start;
-		port->irq = res2->start;
+		port->irq = irq;
 		port->dev = &pdev->dev;
 		port->uartclk = clk;
 		dev_set_drvdata(&pdev->dev, port);