serial: mvebu-uart: add soft reset at probe

The existing UART driver relies on the bootloader to initialize the
port(s). However, the secondary uart port may not be initialized
properly in early boot stage. This patch adds the UART soft reset when
probing, for all ports.
Signed-off-by: NAllen Yan <yanwei@marvell.com>
Signed-off-by: NMiquel Raynal <miquel.raynal@free-electrons.com>
Reviewed-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/mvebu-uart.c

@@ -660,6 +660,11 @@ static int mvebu_uart_probe(struct platform_device *pdev)
 	port->private_data = mvuart;
 	platform_set_drvdata(pdev, mvuart);
 
+	/* UART Soft Reset*/
+	writel(CTRL_SOFT_RST, port->membase + UART_CTRL(port));
+	udelay(1);
+	writel(0, port->membase + UART_CTRL(port));
+
 	ret = uart_add_one_port(&mvebu_uart_driver, port);
 	if (ret)
 		return ret;