drivers: PL011: refactor pl011_shutdown()

Split the pl011_shutdown() 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

@@ -1635,34 +1635,15 @@ static void pl011_shutdown_channel(struct uart_amba_port *uap,
       writew(val, uap->port.membase + lcrh);
 }
 
-static void pl011_shutdown(struct uart_port *port)
+/*
+ * disable the port. It should not disable RTS and DTR.
+ * Also RTS and DTR state should be preserved to restore
+ * it during startup().
+ */
+static void pl011_disable_uart(struct uart_amba_port *uap)
 {
-	struct uart_amba_port *uap =
-	    container_of(port, struct uart_amba_port, port);
 	unsigned int cr;
 
-	/*
-	 * disable all interrupts
-	 */
-	spin_lock_irq(&uap->port.lock);
-	uap->im = 0;
-	writew(uap->im, uap->port.membase + UART011_IMSC);
-	writew(0xffff, uap->port.membase + UART011_ICR);
-	spin_unlock_irq(&uap->port.lock);
-
-	pl011_dma_shutdown(uap);
-
-	/*
-	 * Free the interrupt
-	 */
-	free_irq(uap->port.irq, uap);
-
-	/*
-	 * disable the port
-	 * disable the port. It should not disable RTS and DTR.
-	 * Also RTS and DTR state should be preserved to restore
-	 * it during startup().
-	 */
 	uap->autorts = false;
 	spin_lock_irq(&uap->port.lock);
 	cr = readw(uap->port.membase + UART011_CR);
@@ -1678,6 +1659,32 @@ static void pl011_shutdown(struct uart_port *port)
 	pl011_shutdown_channel(uap, uap->lcrh_rx);
 	if (uap->lcrh_rx != uap->lcrh_tx)
 		pl011_shutdown_channel(uap, uap->lcrh_tx);
+}
+
+static void pl011_disable_interrupts(struct uart_amba_port *uap)
+{
+	spin_lock_irq(&uap->port.lock);
+
+	/* mask all interrupts and clear all pending ones */
+	uap->im = 0;
+	writew(uap->im, uap->port.membase + UART011_IMSC);
+	writew(0xffff, uap->port.membase + UART011_ICR);
+
+	spin_unlock_irq(&uap->port.lock);
+}
+
+static void pl011_shutdown(struct uart_port *port)
+{
+	struct uart_amba_port *uap =
+		container_of(port, struct uart_amba_port, port);
+
+	pl011_disable_interrupts(uap);
+
+	pl011_dma_shutdown(uap);
+
+	free_irq(uap->port.irq, uap);
+
+	pl011_disable_uart(uap);
 
 	/*
 	 * Shut down the clock producer