From a4c639b04f301ddc3f71bc0f2600c3759846db43 Mon Sep 17 00:00:00 2001 From: Rob Herring Date: Mon, 26 Jan 2015 22:50:09 -0600 Subject: [PATCH] tty/serial: 8250_early: Add support for PXA UARTs The PXA variant of the 8250 UART adds a UART enable bit which must not be cleared. Make the earlycon support maintain this bit if it is set. This implies some initialization of the UART, but we cannot unconditionally set the bit as some other variants require this bit to be clear for other functions. Signed-off-by: Rob Herring Cc: Greg Kroah-Hartman Cc: Jiri Slaby Cc: linux-serial@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_early.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c index ce2a8abd1f54..c31a22b4f845 100644 --- a/drivers/tty/serial/8250/8250_early.c +++ b/drivers/tty/serial/8250/8250_early.c @@ -93,10 +93,10 @@ static void __init early_serial8250_write(struct console *console, struct uart_port *port = &early_device->port; unsigned int ier; - /* Save the IER and disable interrupts */ + /* Save the IER and disable interrupts preserving the UUE bit */ ier = serial8250_early_in(port, UART_IER); if (ier) - serial8250_early_out(port, UART_IER, 0); + serial8250_early_out(port, UART_IER, ier & UART_IER_UUE); uart_console_write(port, s, count, serial_putc); @@ -127,9 +127,11 @@ static void __init init_port(struct earlycon_device *device) struct uart_port *port = &device->port; unsigned int divisor; unsigned char c; + unsigned int ier; serial8250_early_out(port, UART_LCR, 0x3); /* 8n1 */ - serial8250_early_out(port, UART_IER, 0); /* no interrupt */ + ier = serial8250_early_in(port, UART_IER); + serial8250_early_out(port, UART_IER, ier & UART_IER_UUE); /* no interrupt */ serial8250_early_out(port, UART_FCR, 0); /* no fifo */ serial8250_early_out(port, UART_MCR, 0x3); /* DTR + RTS */ -- 2.11.0