drivers: PL011: refactor pl011_startup()

Split the pl011_startup() function into smaller chunks to allow
easier reuse later when adding SBSA support.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/amba-pl011.c

@@ -1556,6 +1556,32 @@ static void pl011_write_lcr_h(struct uart_amba_port *uap, unsigned int lcr_h)
 	}
 }
 
+static int pl011_allocate_irq(struct uart_amba_port *uap)
+{
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+
+	return request_irq(uap->port.irq, pl011_int, 0, "uart-pl011", uap);
+}
+
+/*
+ * Enable interrupts, only timeouts when using DMA
+ * if initial RX DMA job failed, start in interrupt mode
+ * as well.
+ */
+static void pl011_enable_interrupts(struct uart_amba_port *uap)
+{
+	spin_lock_irq(&uap->port.lock);
+
+	/* Clear out any spuriously appearing RX interrupts */
+	writew(UART011_RTIS | UART011_RXIS,
+	       uap->port.membase + UART011_ICR);
+	uap->im = UART011_RTIM;
+	if (!pl011_dma_rx_running(uap))
+		uap->im |= UART011_RXIM;
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+	spin_unlock_irq(&uap->port.lock);
+}
+
 static int pl011_startup(struct uart_port *port)
 {
 	struct uart_amba_port *uap =
@@ -1567,12 +1593,7 @@ static int pl011_startup(struct uart_port *port)
 	if (retval)
 		goto clk_dis;
 
-	writew(uap->im, uap->port.membase + UART011_IMSC);
-
-	/*
-	 * Allocate the IRQ
-	 */
-	retval = request_irq(uap->port.irq, pl011_int, 0, "uart-pl011", uap);
+	retval = pl011_allocate_irq(uap);
 	if (retval)
 		goto clk_dis;
 
@@ -1595,20 +1616,7 @@ static int pl011_startup(struct uart_port *port)
 	/* Startup DMA */
 	pl011_dma_startup(uap);
 
-	/*
-	 * Finally, enable interrupts, only timeouts when using DMA
-	 * if initial RX DMA job failed, start in interrupt mode
-	 * as well.
-	 */
-	spin_lock_irq(&uap->port.lock);
-	/* Clear out any spuriously appearing RX interrupts */
-	 writew(UART011_RTIS | UART011_RXIS,
-		uap->port.membase + UART011_ICR);
-	uap->im = UART011_RTIM;
-	if (!pl011_dma_rx_running(uap))
-		uap->im |= UART011_RXIM;
-	writew(uap->im, uap->port.membase + UART011_IMSC);
-	spin_unlock_irq(&uap->port.lock);
+	pl011_enable_interrupts(uap);
 
 	return 0;