linux-kernel - [PATCH RESEND 4/8] serial: 8250: add RX_DURING

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Date:	Fri,  9 Dec 2011 18:07:16 +0100
From:	Wolfram Sang <w.sang@...gutronix.de>
To:	linux-serial@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Greg KH <gregkh@...e.de>,
	Alan Cox <alan@...ux.intel.com>,
	Claudio Scordino <claudio@...dence.eu.com>,
	Wolfram Sang <w.sang@...gutronix.de>,
	Juergen Beisert <jbe@...gutronix.de>
Subject: [PATCH RESEND 4/8] serial: 8250: add RX_DURING_TX capability to RS485 mode

To prevent echo in some configurations, make sure we do not read back
when we are sending if RS485 is configured this way. We need to shuffle
stop_rx() around, implement start_rx() and call it in apropriate places.

Signed-off-by: Juergen Beisert <jbe@...gutronix.de>
Signed-off-by: Wolfram Sang <w.sang@...gutronix.de>
---
 drivers/tty/serial/8250.c |   34 +++++++++++++++++++++++++---------
 1 files changed, 25 insertions(+), 9 deletions(-)

diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c
index b5d3248..6a2f47f 100644
--- a/drivers/tty/serial/8250.c
+++ b/drivers/tty/serial/8250.c
@@ -1304,6 +1304,26 @@ static void autoconfig_irq(struct uart_8250_port *up)
 	up->port.irq = (irq > 0) ? irq : 0;
 }
 
+static void serial8250_stop_rx(struct uart_port *port)
+{
+	struct uart_8250_port *up =
+		container_of(port, struct uart_8250_port, port);
+
+	up->ier &= ~UART_IER_RLSI;
+	up->port.read_status_mask &= ~UART_LSR_DR;
+	serial_out(up, UART_IER, up->ier);
+}
+
+static void serial8250_start_rx(struct uart_port *port)
+{
+	struct uart_8250_port *up =
+		container_of(port, struct uart_8250_port, port);
+
+	up->ier |= UART_IER_RLSI;
+	up->port.read_status_mask |= UART_LSR_DR;
+	serial_out(up, UART_IER, up->ier);
+}
+
 static inline void __stop_tx(struct uart_8250_port *p)
 {
 	if (p->ier & UART_IER_THRI) {
@@ -1326,6 +1346,9 @@ static void serial8250_stop_tx(struct uart_port *port)
 		up->acr |= UART_ACR_TXDIS;
 		serial_icr_write(up, UART_ACR, up->acr);
 	}
+
+	if (!(up->rs485_flags & SER_RS485_RX_DURING_TX))
+		serial8250_start_rx(port);
 }
 
 static void transmit_chars(struct uart_8250_port *up);
@@ -1357,16 +1380,9 @@ static void serial8250_start_tx(struct uart_port *port)
 		up->acr &= ~UART_ACR_TXDIS;
 		serial_icr_write(up, UART_ACR, up->acr);
 	}
-}
 
-static void serial8250_stop_rx(struct uart_port *port)
-{
-	struct uart_8250_port *up =
-		container_of(port, struct uart_8250_port, port);
-
-	up->ier &= ~UART_IER_RLSI;
-	up->port.read_status_mask &= ~UART_LSR_DR;
-	serial_out(up, UART_IER, up->ier);
+	if (!(up->rs485_flags & SER_RS485_RX_DURING_TX))
+		serial8250_stop_rx(port);
 }
 
 static void serial8250_enable_ms(struct uart_port *port)
-- 
1.7.7.3

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