On Wed, Feb 16, 2022 at 01:17:55AM +0100, Lino Sanfilippo wrote:
> Several drivers that support setting the RS485 configuration via userspace
> implement one or more of the following tasks:
>
> - in case of an invalid RTS configuration (both RTS after send and RTS on
> send set or both unset) fall back to enable RTS on send and disable RTS
> after send
>
> - nullify the padding field of the returned serial_rs485 struct
>
> - copy the configuration into the uart port struct
>
> - limit RTS delays to 100 ms
>
> Move these tasks into the serial core to make them generic and to provide
> a consistent behaviour among all drivers.
>
> Signed-off-by: Lino Sanfilippo <LinoSanfilippo@xxxxxx>
> ---
> drivers/tty/serial/serial_core.c | 18 ++++++++++++++++++
> include/uapi/linux/serial.h | 3 +++
> 2 files changed, 21 insertions(+)
>
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index 846192a7b4bf..a4f7e847d414 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -1282,8 +1282,26 @@ static int uart_set_rs485_config(struct uart_port *port,
> if (copy_from_user(&rs485, rs485_user, sizeof(*rs485_user)))
> return -EFAULT;
>
> + /* pick sane settings if the user hasn't */
> + if (!(rs485.flags & SER_RS485_RTS_ON_SEND) ==
> + !(rs485.flags & SER_RS485_RTS_AFTER_SEND)) {
> + rs485.flags |= SER_RS485_RTS_ON_SEND;
> + rs485.flags &= ~SER_RS485_RTS_AFTER_SEND;
> + }
> +
> + rs485.delay_rts_before_send = min_t(unsigned int,
> + rs485.delay_rts_before_send,
> + SER_RS485_MAX_RTS_DELAY);
> + rs485.delay_rts_after_send = min_t(unsigned int,
> + rs485.delay_rts_after_send,
> + SER_RS485_MAX_RTS_DELAY);
> + /* Return clean padding area to userspace */
> + memset(rs485.padding, 0, sizeof(rs485.padding));
> +
> spin_lock_irqsave(&port->lock, flags);
> ret = port->rs485_config(port, &rs485);
> + if (!ret)
> + port->rs485 = rs485;
> spin_unlock_irqrestore(&port->lock, flags);
> if (ret)
> return ret;
> diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h
> index fa6b16e5fdd8..859045a53231 100644
> --- a/include/uapi/linux/serial.h
> +++ b/include/uapi/linux/serial.h
> @@ -128,6 +128,9 @@ struct serial_rs485 {
> (if supported) */
> __u32 delay_rts_before_send; /* Delay before send (milliseconds) */
> __u32 delay_rts_after_send; /* Delay after send (milliseconds) */
> +#define SER_RS485_MAX_RTS_DELAY 100 /* Max time with active
> + RTS before/after
> + data sent (msecs) */
Why is this a userspace value now? What can userspace do with this
number? Once we add this, it's fixed for forever.
thanks,
greg k-h
