This makes sense. I did have to fix up my user space app to set
SER_RS485_RTS_ON_SEND after applying this patch.
On Mon, 16 Mar 2015, Jakub Kicinski wrote:
> From: Jakub Kicinski <kubakici@xxxxx>
>
> Hardware is capable of inverting RTS signal when working
> in RS-485 mode. Expose this functionality to user space.
> Relay on a matching combination of standard flags
> (SER_RS485_RTS_ON_SEND and SER_RS485_RTS_AFTER_SEND) to
> detect when user space is requesting inverted RTS mode.
>
> Signed-off-by: Jakub Kicinski <kubakici@xxxxx>
Signed-off-by: Jon Ringle <jringle@xxxxxxxxxxxxx>
> ---
> drivers/tty/serial/sc16is7xx.c | 32 +++++++++++++++++++++++---------
> 1 file changed, 23 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
> index e6b396e584f3..24902d589b07 100644
> --- a/drivers/tty/serial/sc16is7xx.c
> +++ b/drivers/tty/serial/sc16is7xx.c
> @@ -829,16 +829,30 @@ static void sc16is7xx_set_termios(struct uart_port *port,
> }
>
> static int sc16is7xx_config_rs485(struct uart_port *port,
> - struct serial_rs485 *rs485)
> + struct serial_rs485 *rs485)
> {
> - if (port->rs485.flags & SER_RS485_ENABLED)
> - sc16is7xx_port_update(port, SC16IS7XX_EFCR_REG,
> - SC16IS7XX_EFCR_AUTO_RS485_BIT,
> - SC16IS7XX_EFCR_AUTO_RS485_BIT);
> - else
> - sc16is7xx_port_update(port, SC16IS7XX_EFCR_REG,
> - SC16IS7XX_EFCR_AUTO_RS485_BIT,
> - 0);
> + const u32 mask = SC16IS7XX_EFCR_AUTO_RS485_BIT |
> + SC16IS7XX_EFCR_RTS_INVERT_BIT;
> + u32 efcr = 0;
> +
> + if (rs485->flags & SER_RS485_ENABLED) {
> + bool rts_during_rx, rts_during_tx;
> +
> + rts_during_rx = rs485->flags & SER_RS485_RTS_AFTER_SEND;
> + rts_during_tx = rs485->flags & SER_RS485_RTS_ON_SEND;
> +
> + efcr |= SC16IS7XX_EFCR_AUTO_RS485_BIT;
> +
> + if (!rts_during_rx && rts_during_tx)
> + /* default */;
> + else if (rts_during_rx && !rts_during_tx)
> + efcr |= SC16IS7XX_EFCR_RTS_INVERT_BIT;
> + else
> + return -EINVAL;
> + }
> +
> + sc16is7xx_port_update(port, SC16IS7XX_EFCR_REG, mask, efcr);
> +
> port->rs485 = *rs485;
>
> return 0;
> --
> 2.1.0
>
>
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