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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 <robh@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: linux-serial@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Rob Herring 2015-01-26 22:50:09 -06:00 committed by Greg Kroah-Hartman
parent 6ad991b699
commit a4c639b04f
1 changed files with 5 additions and 3 deletions
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8
drivers/tty/serial/8250/8250_early.c
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@ -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 */