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serial: core: introduce uart_port_tx_flags()

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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@kernel.org>
Cc: stable <stable@kernel.org>
Tested-by: Emil Kronborg <emil.kronborg@protonmail.com>
Link: https://lore.kernel.org/r/20240201105557.28043-1-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby (SUSE) 2024-02-01 11:55:56 +01:00 committed by Greg Kroah-Hartman
parent 720e78d7fa
commit 3ee07964d4
1 changed files with 27 additions and 5 deletions
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32
include/linux/serial_core.h
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@ -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.
*/