On Thu, Feb 01, 2024 at 11:55 +0100, Jiri Slaby (SUSE) wrote:
> And an enum with a flag: UART_TX_NOSTOP. To NOT call
> __port->ops->stop_tx() when the circular buffer is empty. mxs-uart needs
> this (see the next patch).
>
> Signed-off-by: Jiri Slaby (SUSE) <jirislaby@xxxxxxxxxx>
> Cc: Emil Kronborg <emil.kronborg@xxxxxxxxxxxxxx>
> ---
>
> Notes:
> [v2] fix/invert the condition
>
> include/linux/serial_core.h | 32 +++++++++++++++++++++++++++-----
> 1 file changed, 27 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
> index 536b2581d3e2..55b1f3ba48ac 100644
> --- a/include/linux/serial_core.h
> +++ b/include/linux/serial_core.h
> @@ -748,8 +748,17 @@ struct uart_driver {
>
> void uart_write_wakeup(struct uart_port *port);
>
> -#define __uart_port_tx(uport, ch, tx_ready, put_char, tx_done, for_test, \
> - for_post) \
> +/**
> + * enum UART_TX_FLAGS -- flags for uart_port_tx_flags()
> + *
> + * @UART_TX_NOSTOP: don't call port->ops->stop_tx() on empty buffer
> + */
> +enum UART_TX_FLAGS {
> + UART_TX_NOSTOP = BIT(0),
> +};
> +
> +#define __uart_port_tx(uport, ch, flags, tx_ready, put_char, tx_done, \
> + for_test, for_post) \
> ({ \
> struct uart_port *__port = (uport); \
> struct circ_buf *xmit = &__port->state->xmit; \
> @@ -777,7 +786,7 @@ void uart_write_wakeup(struct uart_port *port);
> if (pending < WAKEUP_CHARS) { \
> uart_write_wakeup(__port); \
> \
> - if (pending == 0) \
> + if (!((flags) & UART_TX_NOSTOP) && pending == 0) \
> __port->ops->stop_tx(__port); \
> } \
> \
> @@ -812,7 +821,7 @@ void uart_write_wakeup(struct uart_port *port);
> */
> #define uart_port_tx_limited(port, ch, count, tx_ready, put_char, tx_done) ({ \
> unsigned int __count = (count); \
> - __uart_port_tx(port, ch, tx_ready, put_char, tx_done, __count, \
> + __uart_port_tx(port, ch, 0, tx_ready, put_char, tx_done, __count, \
> __count--); \
> })
>
> @@ -826,8 +835,21 @@ void uart_write_wakeup(struct uart_port *port);
> * See uart_port_tx_limited() for more details.
> */
> #define uart_port_tx(port, ch, tx_ready, put_char) \
> - __uart_port_tx(port, ch, tx_ready, put_char, ({}), true, ({}))
> + __uart_port_tx(port, ch, 0, tx_ready, put_char, ({}), true, ({}))
> +
>
> +/**
> + * uart_port_tx_flags -- transmit helper for uart_port with flags
> + * @port: uart port
> + * @ch: variable to store a character to be written to the HW
> + * @flags: %UART_TX_NOSTOP or similar
> + * @tx_ready: can HW accept more data function
> + * @put_char: function to write a character
> + *
> + * See uart_port_tx_limited() for more details.
> + */
> +#define uart_port_tx_flags(port, ch, flags, tx_ready, put_char) \
> + __uart_port_tx(port, ch, flags, tx_ready, put_char, ({}), true, ({}))
> /*
> * Baud rate helpers.
> */
> --
> 2.43.0
>
Tested on i.MX28 board.
Tested-by: Emil Kronborg <emil.kronborg@xxxxxxxxxxxxxx>
--
Emil Kronborg
