serial: mvebu-uart: support probe of multiple ports

Until now, the mvebu-uart driver only supported probing a single UART
port. However, some platforms have multiple instances of this UART
controller, and therefore the driver should support multiple ports.

In order to achieve this, we make sure to assign port->line properly,
instead of hardcoding it to zero.
Signed-off-by: Allen Yan <yanwei@marvell.com>
Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/mvebu-uart.c

@@ -547,20 +547,36 @@ static struct uart_driver mvebu_uart_driver = {
 #endif
 };
 
+/* Counter to keep track of each UART port id when not using CONFIG_OF */
+static int uart_num_counter;
+
 static int mvebu_uart_probe(struct platform_device *pdev)
 {
 	struct resource *reg = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 	struct uart_port *port;
 	struct mvebu_uart_data *data;
-	int ret;
+	int ret, id;
 
 	if (!reg || !irq) {
 		dev_err(&pdev->dev, "no registers/irq defined\n");
 		return -EINVAL;
 	}
 
-	port = &mvebu_uart_ports[0];
+	/* Assume that all UART ports have a DT alias or none has */
+	id = of_alias_get_id(pdev->dev.of_node, "serial");
+	if (!pdev->dev.of_node || id < 0)
+		pdev->id = uart_num_counter++;
+	else
+		pdev->id = id;
+
+	if (pdev->id >= MVEBU_NR_UARTS) {
+		dev_err(&pdev->dev, "cannot have more than %d UART ports\n",
+			MVEBU_NR_UARTS);
+		return -EINVAL;
+	}
+
+	port = &mvebu_uart_ports[pdev->id];
 
 	spin_lock_init(&port->lock);
 
@@ -572,7 +588,7 @@ static int mvebu_uart_probe(struct platform_device *pdev)
 	port->fifosize   = 32;
 	port->iotype     = UPIO_MEM32;
 	port->flags      = UPF_FIXED_PORT;
-	port->line       = 0; /* single port: force line number to  0 */
+	port->line       = pdev->id;
 
 	port->irq        = irq->start;
 	port->irqflags   = 0;