serial: imx: Fix the reporting of interrupts

On a imx system with ttymxc0, ttymxc1 and ttymxc4 registered we see the
following output from 'cat /proc/interrupts':

$ cat /proc/interrupts
           CPU0
...
 58:         39       GIC  58  2020000.serial
 67:        115       GIC  67  21f8000.i2c

The only uart irq that appears is ttymxc0, which is the console.

As ttymxc1 and ttymxc4 will only have their irq registered at imx_startup(),
they are not shown right after probe.

Transmitting to ttymxc1 and ttymxc4 will cause their irqs to be registered, but
the output shows:

$ echo "111111" > /dev/ttymxc1
$ echo "444444" > /dev/ttymxc4
$ cat /proc/interrupts
           CPU0
...
 58:        150       GIC  58  2020000.serial
 59:          1       GIC  59
 62:          1       GIC  62
 67:        115       GIC  67  21f8000.i2c

,which misses printing the associated device address.

In order to fix this, register all the irqs inside the probe function via
devm_request_irq(), which will correctly report the serial interrupts associated
with their correspondent serial device and also helps simplyfing the code by
avoiding the calls to free_irq().

$ echo "111111" > /dev/ttymxc1
$ echo "444444" > /dev/ttymxc4
$ cat /proc/interrupts

	   CPU0
....
 58:        202       GIC  58  2020000.serial
 59:          1       GIC  59  21e8000.serial
 62:          1       GIC  62  21f4000.serial
 67:        115       GIC  67  21f8000.i2c

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/imx.c

@@ -1109,37 +1109,6 @@ static int imx_startup(struct uart_port *port)
 	while (!(readl(sport->port.membase + UCR2) & UCR2_SRST) && (--i > 0))
 		udelay(1);
 
-	/*
-	 * Allocate the IRQ(s) i.MX1 has three interrupts whereas later
-	 * chips only have one interrupt.
-	 */
-	if (sport->txirq > 0) {
-		retval = request_irq(sport->rxirq, imx_rxint, 0,
-				     dev_name(port->dev), sport);
-		if (retval)
-			goto error_out1;
-
-		retval = request_irq(sport->txirq, imx_txint, 0,
-				     dev_name(port->dev), sport);
-		if (retval)
-			goto error_out2;
-
-		/* do not use RTS IRQ on IrDA */
-		if (!USE_IRDA(sport)) {
-			retval = request_irq(sport->rtsirq, imx_rtsint, 0,
-					     dev_name(port->dev), sport);
-			if (retval)
-				goto error_out3;
-		}
-	} else {
-		retval = request_irq(sport->port.irq, imx_int, 0,
-				     dev_name(port->dev), sport);
-		if (retval) {
-			free_irq(sport->port.irq, sport);
-			goto error_out1;
-		}
-	}
-
 	spin_lock_irqsave(&sport->port.lock, flags);
 	/*
 	 * Finally, clear and enable interrupts
@@ -1202,12 +1171,6 @@ static int imx_startup(struct uart_port *port)
 
 	return 0;
 
-error_out3:
-	if (sport->txirq)
-		free_irq(sport->txirq, sport);
-error_out2:
-	if (sport->rxirq)
-		free_irq(sport->rxirq, sport);
 error_out1:
 	return retval;
 }
@@ -1254,17 +1217,6 @@ static void imx_shutdown(struct uart_port *port)
 	 */
 	del_timer_sync(&sport->timer);
 
-	/*
-	 * Free the interrupts
-	 */
-	if (sport->txirq > 0) {
-		if (!USE_IRDA(sport))
-			free_irq(sport->rtsirq, sport);
-		free_irq(sport->txirq, sport);
-		free_irq(sport->rxirq, sport);
-	} else
-		free_irq(sport->port.irq, sport);
-
 	/*
 	 * Disable all interrupts, port and break condition.
 	 */
@@ -1929,6 +1881,36 @@ static int serial_imx_probe(struct platform_device *pdev)
 
 	sport->port.uartclk = clk_get_rate(sport->clk_per);
 
+	/*
+	 * Allocate the IRQ(s) i.MX1 has three interrupts whereas later
+	 * chips only have one interrupt.
+	 */
+	if (sport->txirq > 0) {
+		ret = devm_request_irq(&pdev->dev, sport->rxirq, imx_rxint, 0,
+				       dev_name(&pdev->dev), sport);
+		if (ret)
+			return ret;
+
+		ret = devm_request_irq(&pdev->dev, sport->txirq, imx_txint, 0,
+				       dev_name(&pdev->dev), sport);
+		if (ret)
+			return ret;
+
+		/* do not use RTS IRQ on IrDA */
+		if (!USE_IRDA(sport)) {
+			ret = devm_request_irq(&pdev->dev, sport->rtsirq,
+					       imx_rtsint, 0,
+					       dev_name(&pdev->dev), sport);
+			if (ret)
+				return ret;
+		}
+	} else {
+		ret = devm_request_irq(&pdev->dev, sport->port.irq, imx_int, 0,
+				       dev_name(&pdev->dev), sport);
+		if (ret)
+			return ret;
+	}
+
 	imx_ports[sport->port.line] = sport;
 
 	platform_set_drvdata(pdev, sport);