From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Herring Subject: [PATCH 3/3] tty/serial: 8250_early: Add support for PXA UARTs Date: Mon, 26 Jan 2015 22:50:09 -0600 Message-ID: <1422334209-23125-3-git-send-email-robh@kernel.org> References: <1422334209-23125-1-git-send-email-robh@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1422334209-23125-1-git-send-email-robh@kernel.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: linux-serial@vger.kernel.org Cc: Rob Herring , Jiri Slaby , linux-arm-kernel@lists.infradead.org, Greg Kroah-Hartman List-Id: linux-serial@vger.kernel.org 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 --- 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 ce2a8ab..c31a22b 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 */ -- 2.1.0