[PATCH] atmel_serial: RS485: receiving enabled when sending data
Claudio Scordino
claudio at evidence.eu.com
Wed Aug 24 03:48:23 EDT 2011
Il 23/08/2011 17:39, Greg KH ha scritto:
> On Tue, Aug 23, 2011 at 10:30:46AM +0200, Claudio Scordino wrote:
>> Il 22/08/2011 23:18, Greg KH ha scritto:
>>> On Mon, Aug 15, 2011 at 04:28:15PM +0200, Bernhard Roth wrote:
>>>> 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<br at pwrnet.de>
>>>> Signed-off-by: Claudio Scordino<claudio at evidence.eu.com>
>>>> ---
>>>> 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<foo at foo.org>
>
> 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 <br at pwrnet.de>
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 <br at pwrnet.de>
Signed-off-by: Claudio Scordino <claudio at evidence.eu.com>
Acked-by: Alan Cox <alan at linux.intel.com>
---
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
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