[PATCH] atmel_serial: RS485: receiving enabled when sending data

Il 23/08/2011 17:39, Greg KH ha scritto:

On Tue, Aug 23, 2011 at 10:30:46AM +0200, Claudio Scordino wrote:

quoted

Il 22/08/2011 23:18, Greg KH ha scritto:

quoted

On Mon, Aug 15, 2011 at 04:28:15PM +0200, Bernhard Roth wrote:

quoted

Hello!

By default the atmel_serial driver in RS485 mode disables receiving
data until all data in the send buffer has been sent. This flag
allows to receive data even whilst sending data. This is very useful
to

- check if the data has been sent correctly over the RS485 bus
- assure that no collision happened
- check for short circuits/termination issues on the RS485 bus

Usually this functionality is realized by hardware, wether
controlling the RX-Enable pin of the RS485 transceiver with RTS
(driver control signal) or pulling it LOW permanently. The present
atmel_serial driver makes this impossible, thus requiring following
patch.

Usage example:

      struct serial_rs485     rs485;

      memset(&rs485, 0, sizeof(rs485));
      rs485.flags = SER_RS485_ENABLED | SER_RS485_RX_DURING_TX;
      ioctl(fd, TIOCSRS485,&rs485);




atmel_serial: RS485: receiving enabled when sending data

By default the atmel_serial driver in RS485 mode disables receiving
data until
all data in the send buffer has been sent. This flag allows to receive data
even whilst sending data.

Signed-off-by: Bernhard Roth<redacted>
Signed-off-by: Claudio Scordino<redacted>
---
   drivers/tty/serial/atmel_serial.c |   17 ++++++++++-------
   include/linux/serial.h            |    1 +
   2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/tty/serial/atmel_serial.c

b/drivers/tty/serial/atmel_serial.c
index af9b781..5f6c745 100644

--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c

@@ -339,8 +339,9 @@ static void atmel_stop_tx(struct uart_port *port)
       /* Disable interrupts */
       UART_PUT_IDR(port, atmel_port->tx_done_mask);

-    if (atmel_port->rs485.flags&   SER_RS485_ENABLED)
-        atmel_start_rx(port);
+    if ((atmel_port->rs485.flags&   SER_RS485_ENABLED)&&
+        !(atmel_port->rs485.flags&   SER_RS485_RX_DURING_TX))
+            atmel_start_rx(port);

Can you fix your email client to not strip patches of tabs and resend
this so that I can apply it?

thanks,

greg k-h

Hi Greg,

     please find below the patch with the right tabs.

Remind however that the main author of the patch is Bernhard, not me.

Then properly send the patch so that this is shown.  Please just add a:

From: foo<redacted>

as the first line of the patch changelog portion and git will fix things
up correctly.  Documentation/SubmittingPatches describes this in detail.

Care to resend your updated version, with this corrected author
information, so I get it right?

Here it is. I also added a few lines in the Documentation.

Many thanks,

	Claudio

Subject: atmel_serial: RS485: receiving enabled when sending data
From: Bernhard Roth <redacted> 

By default the atmel_serial driver in RS485 mode disables receiving data until
all data in the send buffer has been sent. This flag allows to receive data
even whilst sending data.

Signed-off-by: Bernhard Roth <redacted> 
Signed-off-by: Claudio Scordino <redacted>
Acked-by: Alan Cox <redacted>
---
 Documentation/serial/serial-rs485.txt |    3 +++
 drivers/tty/serial/atmel_serial.c     |    9 ++++++---
 include/linux/serial.h                |    1 +
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/Documentation/serial/serial-rs485.txt b/Documentation/serial/serial-rs485.txt
index a493238..c8878f8 100644
--- a/Documentation/serial/serial-rs485.txt
+++ b/Documentation/serial/serial-rs485.txt

@@ -104,6 +104,9 @@
 	rs485conf.flags |= SER_RS485_RTS_AFTER_SEND;
 	rs485conf.delay_rts_after_send = ...;
 
+	/* Set this flag if you want to receive data even whilst sending data */
+	rs485conf.flags |= SER_RS485_RX_DURING_TX;
+
 	if (ioctl (fd, TIOCSRS485, &rs485conf) < 0) {
 		/* Error handling. See errno. */
 	}

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index af9b781..c7232a9 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c

@@ -339,7 +339,8 @@ static void atmel_stop_tx(struct uart_port *port)
 	/* Disable interrupts */
 	UART_PUT_IDR(port, atmel_port->tx_done_mask);
 
-	if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+	if ((atmel_port->rs485.flags & SER_RS485_ENABLED) &&
+	    !(atmel_port->rs485.flags & SER_RS485_RX_DURING_TX))
 		atmel_start_rx(port);
 }
 

@@ -356,7 +357,8 @@ static void atmel_start_tx(struct uart_port *port)
 			   really need this.*/
 			return;
 
-		if (atmel_port->rs485.flags & SER_RS485_ENABLED)
+		if ((atmel_port->rs485.flags & SER_RS485_ENABLED) &&
+		    !(atmel_port->rs485.flags & SER_RS485_RX_DURING_TX))
 			atmel_stop_rx(port);
 
 		/* re-enable PDC transmit */

@@ -680,7 +682,8 @@ static void atmel_tx_dma(struct uart_port *port)
 		/* Enable interrupts */
 		UART_PUT_IER(port, atmel_port->tx_done_mask);
 	} else {
-		if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
+		if ((atmel_port->rs485.flags & SER_RS485_ENABLED) &&
+		    !(atmel_port->rs485.flags & SER_RS485_RX_DURING_TX)) {
 			/* DMA done, stop TX, start RX for RS485 */
 			atmel_start_rx(port);
 		}

diff --git a/include/linux/serial.h b/include/linux/serial.h
index ef91406..97ff8e2 100644
--- a/include/linux/serial.h
+++ b/include/linux/serial.h

@@ -211,6 +211,7 @@ struct serial_rs485 {
 #define SER_RS485_RTS_ON_SEND		(1 << 1)
 #define SER_RS485_RTS_AFTER_SEND	(1 << 2)
 #define SER_RS485_RTS_BEFORE_SEND	(1 << 3)
+#define SER_RS485_RX_DURING_TX		(1 << 4)
 	__u32	delay_rts_before_send;	/* Milliseconds */
 	__u32	delay_rts_after_send;	/* Milliseconds */
 	__u32	padding[5];		/* Memory is cheap, new structs

-- 
1.7.1