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: Allen Yan <[email protected]>
Signed-off-by: Miquel Raynal <[email protected]>
Reviewed-by: Gregory CLEMENT <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Allen Yan

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;