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serial: stm32: add support for "flush_buffer" ops

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Add the support for "flush_buffer" ops in order to flush any write buffers,
reset any DMA state and stop any ongoing DMA transfers when the
port->state->xmit circular buffer is cleared.

Signed-off-by: Erwan Le Ray <erwan.leray@foss.st.com>
Link: https://lore.kernel.org/r/20210304162308.8984-14-erwan.leray@foss.st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Erwan Le Ray 2021-03-04 17:23:08 +01:00 committed by Greg Kroah-Hartman
parent 3db1d52466
commit 3d82be8be6
1 changed files with 14 additions and 0 deletions
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14
drivers/tty/serial/stm32-usart.c
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@ -597,6 +597,19 @@ static void stm32_usart_start_tx(struct uart_port *port)
stm32_usart_transmit_chars(port);
}
/* Flush the transmit buffer. */
static void stm32_usart_flush_buffer(struct uart_port *port)
{
struct stm32_port *stm32_port = to_stm32_port(port);
const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
if (stm32_port->tx_ch) {
dmaengine_terminate_async(stm32_port->tx_ch);
stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAT);
stm32_port->tx_dma_busy = false;
}
}
/* Throttle the remote when input buffer is about to overflow. */
static void stm32_usart_throttle(struct uart_port *port)
{
@ -992,6 +1005,7 @@ static const struct uart_ops stm32_uart_ops = {
.break_ctl = stm32_usart_break_ctl,
.startup = stm32_usart_startup,
.shutdown = stm32_usart_shutdown,
.flush_buffer = stm32_usart_flush_buffer,
.set_termios = stm32_usart_set_termios,
.pm = stm32_usart_pm,
.type = stm32_usart_type,