[PATCH] serial: mps2-uart: Initialize early console
From: linux@roeck-us.net (Guenter Roeck)
Date: 2018-06-19 04:55:05
Also in:
linux-serial, lkml
Subsystem:
the rest, tty layer and serial drivers · Maintainers:
Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
The early console code for mps2-uart assumes that the serial hardware is enabled for transmit when the system boots. However, this is not the case after reset. This results in a hang in mps2_early_putchar() if the serial transmitter is not enabled by a boot loader or ROM monitor. Signed-off-by: Guenter Roeck <linux@roeck-us.net> --- drivers/tty/serial/mps2-uart.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/drivers/tty/serial/mps2-uart.c b/drivers/tty/serial/mps2-uart.c
index 9f8f63719126..0743a0551ce1 100644
--- a/drivers/tty/serial/mps2-uart.c
+++ b/drivers/tty/serial/mps2-uart.c@@ -448,6 +448,14 @@ static struct console mps2_uart_console = { #define MPS2_SERIAL_CONSOLE (&mps2_uart_console) +static void mps2_early_init(struct uart_port *port) +{ + u8 control = readb(port->membase + UARTn_CTRL); + + control |= UARTn_CTRL_TX_ENABLE; + writeb(control, port->membase + UARTn_CTRL); +} + static void mps2_early_putchar(struct uart_port *port, int ch) { while (readb(port->membase + UARTn_STATE) & UARTn_STATE_TX_FULL)
@@ -469,6 +477,7 @@ static int __init mps2_early_console_setup(struct earlycon_device *device, if (!device->port.membase) return -ENODEV; + mps2_early_init(&device->port); device->con->write = mps2_early_write; return 0;
--
2.7.4