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SubjectRe: [PATCH 3/3] tty: serial: fsl_lpuart: Add support for RS-485
On 05/29/2015 03:48 PM, Jakub Kiciński wrote:
> On Fri, 29 May 2015 13:35:54 +0530, Bhuvanchandra DV wrote:
>> Enable Vybrid's build-in support for RS-485 auto RTS for
>> controlling line direction of RS-485 transceiver driver.
>>
>> Signed-off-by: Bhuvanchandra DV <bhuvanchandra.dv@toradex.com>
>> ---
>> drivers/tty/serial/fsl_lpuart.c | 60 +++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 60 insertions(+)
>>
>> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
>> index 357f623..c553b14 100644
>> --- a/drivers/tty/serial/fsl_lpuart.c
>> +++ b/drivers/tty/serial/fsl_lpuart.c
>> @@ -820,6 +820,50 @@ static unsigned int lpuart32_tx_empty(struct uart_port *port)
>> TIOCSER_TEMT : 0;
>> }
>>
>> +static int lpuart_config_rs485(struct uart_port *port,
>> + struct serial_rs485 *rs485)
>> +{
>> + struct lpuart_port *sport = container_of(port,
>> + struct lpuart_port, port);
>> + u8 modem = readb(sport->port.membase + UARTMODEM) &
>> + ~(UARTMODEM_TXRTSPOL | UARTMODEM_TXRTSE);
>
> Please put empty line between variables and code.
Ok
>
>> + writeb(modem, sport->port.membase + UARTMODEM);
>> +
>> + if (rs485->flags & SER_RS485_ENABLED) {
>> + /* Enable auto RS-485 RTS mode */
>> + modem |= UARTMODEM_TXRTSE;
>> +
>> + /*
>> + * RTS needs to be logic HIGH either during transer _or_ after
>> + * transfer, other variants are not supported by the hardware.
>> + */
>
> Indentation is off here. '*' should be aligned.
Ok
>
>> + if (!(rs485->flags & (SER_RS485_RTS_ON_SEND |
>> + SER_RS485_RTS_AFTER_SEND)))
>
> and here - things should be aligned on the containing bracket (SER_
> under SER_ here).
Ok
>
>> + rs485->flags |= SER_RS485_RTS_ON_SEND;
>> +
>> + if (rs485->flags & SER_RS485_RTS_ON_SEND &&
>> + rs485->flags & SER_RS485_RTS_AFTER_SEND)
>
> and here - same bracket rule (rs485-> under rs485->)
Ok
>
>> + rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
>> +
>> + /*
>> + * The hardware defaults to RTS logic HIGH while transfer.
>> + * Switch polarity in case RTS shall be logic HIGH
>> + * after transfer.
>> + * Note: UART is assumed to be active high.
>> + */
>> + if (rs485->flags & SER_RS485_RTS_ON_SEND)
>> + modem &= ~UARTMODEM_TXRTSPOL;
>
> UARTMODEM_TXRTSPOL was already clear when you read modem.
Ok
>
>> + else if (rs485->flags & SER_RS485_RTS_AFTER_SEND)
>> + modem |= UARTMODEM_TXRTSPOL;
>> + }
>> +
>> + /* Store the new configuration */
>> + sport->port.rs485 = *rs485;
>> +
>> + writeb(modem, sport->port.membase + UARTMODEM);
>> + return 0;
>> +}
>> +
>> static unsigned int lpuart_get_mctrl(struct uart_port *port)
>> {
>> return TIOCM_CAR | TIOCM_CTS | TIOCM_DSR;
> [...]
>> @@ -1802,6 +1854,14 @@ static int lpuart_probe(struct platform_device *pdev)
>> dev_info(sport->port.dev, "DMA rx channel request failed, "
>> "operating without rx DMA\n");
>>
>> + if (of_property_read_bool(np, "linux,rs485-enabled-at-boot-time")) {
>> + sport->port.rs485.flags |= SER_RS485_ENABLED;
>> + sport->port.rs485.flags |= SER_RS485_RTS_ON_SEND;
>> + writeb(UARTMODEM_TXRTSE, sport->port.membase + UARTMODEM);
>> + } else {
>> + sport->port.rs485.flags &= ~SER_RS485_ENABLED;
>
> Why the need to clear the flag? sport was kzalloc'ed.
Will remove it.
>

Best Regards,
Bhuvan


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