Re: [PATCH 3/3] tty: serial: fsl_lpuart: Add support for RS-485

[Bhuvanchandra DV]

On 05/29/2015 03:48 PM, Jakub KiciÅski 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@xxxxxxxxxxx>
> > ---
> >   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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