Commit 7f28bcea authored by Valentin Caron's avatar Valentin Caron Committed by Greg Kroah-Hartman
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serial: stm32: group dma pause/resume error handling into single function 



Create new function "stm32_usart_dma_pause_resume" that called dmaengine_
pause/resume and in case of error, terminate dma transaction.

Two other functions are created to facilitate the use of stm32_usart_dma
_pause_resume : stm32_usart_tx_dma_pause, stm32_usart_tx_dma_resume.
Equivalent functions for rx will be added in future patch.

Signed-off-by: default avatarValentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20230808161906.178996-5-valentin.caron@foss.st.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 00d1f9c6

drivers/tty/serial/stm32-usart.c

+82 −45
Original line number Diff line number Diff line
@@ -290,14 +290,40 @@ static int stm32_usart_init_rs485(struct uart_port *port, 
}



static bool stm32_usart_rx_dma_started(struct stm32_port *stm32_port)

{

	return stm32_port->rx_ch ? stm32_port->rx_dma_busy : false;

}



static void stm32_usart_rx_dma_terminate(struct stm32_port *stm32_port)

{

	dmaengine_terminate_async(stm32_port->rx_ch);

	stm32_port->rx_dma_busy = false;

}



static int stm32_usart_dma_pause_resume(struct stm32_port *stm32_port,

					struct dma_chan *chan,

					enum dma_status expected_status,

					int dmaengine_pause_or_resume(struct dma_chan *),

					bool stm32_usart_xx_dma_started(struct stm32_port *),

					void stm32_usart_xx_dma_terminate(struct stm32_port *))

{

	struct uart_port *port = &stm32_port->port;

	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;

	enum dma_status dma_status;

	int ret;



	if (!stm32_port->rx_ch)

		return false;

	if (!stm32_usart_xx_dma_started(stm32_port))

		return -EPERM;



	return !!(readl_relaxed(port->membase + ofs->cr3) & USART_CR3_DMAR);

	dma_status = dmaengine_tx_status(chan, chan->cookie, NULL);

	if (dma_status != expected_status)

		return -EAGAIN;



	ret = dmaengine_pause_or_resume(chan);

	if (ret) {

		dev_err(port->dev, "DMA failed with error code: %d\n", ret);

		stm32_usart_xx_dma_terminate(stm32_port);

	}

	return ret;

}



/* Return true when data is pending (in pio mode), and false when no data is pending. */
@@ -475,7 +501,7 @@ static unsigned int stm32_usart_receive_chars(struct uart_port *port, bool force 
			}

		} else {

			/* Disable RX DMA */

			dmaengine_terminate_async(stm32_port->rx_ch);

			stm32_usart_rx_dma_terminate(stm32_port);

			stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR);

			/* Fall back to interrupt mode */

			dev_dbg(port->dev, "DMA error, fallback to irq mode\n");
@@ -506,6 +532,22 @@ static bool stm32_usart_tx_dma_started(struct stm32_port *stm32_port) 
	return stm32_port->tx_dma_busy;

}



static int stm32_usart_tx_dma_pause(struct stm32_port *stm32_port)

{

	return stm32_usart_dma_pause_resume(stm32_port, stm32_port->tx_ch,

					    DMA_IN_PROGRESS, dmaengine_pause,

					    stm32_usart_tx_dma_started,

					    stm32_usart_tx_dma_terminate);

}



static int stm32_usart_tx_dma_resume(struct stm32_port *stm32_port)

{

	return stm32_usart_dma_pause_resume(stm32_port, stm32_port->tx_ch,

					    DMA_PAUSED, dmaengine_resume,

					    stm32_usart_tx_dma_started,

					    stm32_usart_tx_dma_terminate);

}



static void stm32_usart_tx_dma_complete(void *arg)

{

	struct uart_port *port = arg;
@@ -606,13 +648,9 @@ static void stm32_usart_transmit_chars_dma(struct uart_port *port) 
	int ret;



	if (stm32_usart_tx_dma_started(stm32port)) {

		if (dmaengine_tx_status(stm32port->tx_ch,

					stm32port->tx_ch->cookie,

					NULL) == DMA_PAUSED) {

			ret = dmaengine_resume(stm32port->tx_ch);

			if (ret < 0)

				goto dma_err;

		}

		ret = stm32_usart_tx_dma_resume(stm32port);

		if (ret < 0 && ret != -EAGAIN)

			goto fallback_err;

		return;

	}
@@ -658,8 +696,12 @@ static void stm32_usart_transmit_chars_dma(struct uart_port *port) 


	/* Push current DMA TX transaction in the pending queue */

	/* DMA no yet started, safe to free resources */

	if (dma_submit_error(dmaengine_submit(desc)))

		goto dma_err;

	ret = dma_submit_error(dmaengine_submit(desc));

	if (ret) {

		dev_err(port->dev, "DMA failed with error code: %d\n", ret);

		stm32_usart_tx_dma_terminate(stm32port);

		goto fallback_err;

	}



	/* Issue pending DMA TX requests */

	dma_async_issue_pending(stm32port->tx_ch);
@@ -668,10 +710,6 @@ static void stm32_usart_transmit_chars_dma(struct uart_port *port) 


	return;



dma_err:

	dev_err(port->dev, "DMA failed with error code: %d\n", ret);

	stm32_usart_tx_dma_terminate(stm32port);



fallback_err:

	stm32_usart_transmit_chars_pio(port);

}
@@ -693,16 +731,9 @@ static void stm32_usart_transmit_chars(struct uart_port *port) 
	}



	if (port->x_char) {

		if (stm32_usart_tx_dma_started(stm32_port) &&

		    dmaengine_tx_status(stm32_port->tx_ch,

					stm32_port->tx_ch->cookie,

					NULL) == DMA_IN_PROGRESS) {

			ret = dmaengine_pause(stm32_port->tx_ch);

			if (ret < 0) {

				dev_err(port->dev, "DMA failed with error code: %d\n", ret);

				stm32_usart_tx_dma_terminate(stm32_port);

			}

		}

		/* dma terminate may have been called in case of dma pause failure */

		stm32_usart_tx_dma_pause(stm32_port);



		/* Check that TDR is empty before filling FIFO */

		ret =

		readl_relaxed_poll_timeout_atomic(port->membase + ofs->isr,
@@ -716,13 +747,8 @@ static void stm32_usart_transmit_chars(struct uart_port *port) 
		port->x_char = 0;

		port->icount.tx++;



		if (stm32_usart_tx_dma_started(stm32_port)) {

			ret = dmaengine_resume(stm32_port->tx_ch);

			if (ret < 0) {

				dev_err(port->dev, "DMA failed with error code: %d\n", ret);

				stm32_usart_tx_dma_terminate(stm32_port);

			}

		}

		/* dma terminate may have been called in case of dma resume failure */

		stm32_usart_tx_dma_resume(stm32_port);

		return;

	}
@@ -855,16 +881,11 @@ static void stm32_usart_disable_ms(struct uart_port *port) 
static void stm32_usart_stop_tx(struct uart_port *port)

{

	struct stm32_port *stm32_port = to_stm32_port(port);

	int ret;



	stm32_usart_tx_interrupt_disable(port);

	if (stm32_usart_tx_dma_started(stm32_port)) {

		ret = dmaengine_pause(stm32_port->tx_ch);

		if (ret < 0) {

			dev_err(port->dev, "DMA failed with error code: %d\n", ret);

			stm32_usart_tx_dma_terminate(stm32_port);

		}

	}



	/* dma terminate may have been called in case of dma pause failure */

	stm32_usart_tx_dma_pause(stm32_port);



	stm32_usart_rs485_rts_disable(port);

}
@@ -965,8 +986,22 @@ static int stm32_usart_start_rx_dma_cyclic(struct uart_port *port) 
	struct stm32_port *stm32_port = to_stm32_port(port);

	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;

	struct dma_async_tx_descriptor *desc;

	enum dma_status rx_dma_status;

	int ret;



	if (stm32_port->rx_dma_busy) {

		rx_dma_status = dmaengine_tx_status(stm32_port->rx_ch,

						    stm32_port->rx_ch->cookie,

						    NULL);

		if (rx_dma_status == DMA_IN_PROGRESS)

			return 0;



		dev_err(port->dev, "DMA failed : status error.\n");

		stm32_usart_rx_dma_terminate(stm32_port);

	}



	stm32_port->rx_dma_busy = true;



	stm32_port->last_res = RX_BUF_L;

	/* Prepare a DMA cyclic transaction */

	desc = dmaengine_prep_dma_cyclic(stm32_port->rx_ch,
@@ -976,6 +1011,7 @@ static int stm32_usart_start_rx_dma_cyclic(struct uart_port *port) 
					 DMA_PREP_INTERRUPT);

	if (!desc) {

		dev_err(port->dev, "rx dma prep cyclic failed\n");

		stm32_port->rx_dma_busy = false;

		return -ENODEV;

	}
@@ -986,6 +1022,7 @@ static int stm32_usart_start_rx_dma_cyclic(struct uart_port *port) 
	ret = dma_submit_error(dmaengine_submit(desc));

	if (ret) {

		dmaengine_terminate_sync(stm32_port->rx_ch);

		stm32_port->rx_dma_busy = false;

		return ret;

	}
@@ -1074,7 +1111,7 @@ static void stm32_usart_shutdown(struct uart_port *port) 


	/* Disable RX DMA. */

	if (stm32_port->rx_ch)

		dmaengine_terminate_async(stm32_port->rx_ch);

		stm32_usart_rx_dma_terminate(stm32_port);



	/* flush RX & TX FIFO */

	if (ofs->rqr != UNDEF_REG)
@@ -1988,7 +2025,7 @@ static int __maybe_unused stm32_usart_serial_en_wakeup(struct uart_port *port, 
			stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR);

			/* Poll data from DMA RX buffer if any */

			size = stm32_usart_receive_chars(port, true);

			dmaengine_terminate_async(stm32_port->rx_ch);

			stm32_usart_rx_dma_terminate(stm32_port);

			uart_unlock_and_check_sysrq_irqrestore(port, flags);

			if (size)

				tty_flip_buffer_push(tport);

drivers/tty/serial/stm32-usart.h

+1 −0
Original line number Diff line number Diff line
@@ -199,6 +199,7 @@ struct stm32_port { 
	u32 cr3_irq;		 /* USART_CR3_RXFTIE */

	int last_res;

	bool tx_dma_busy;	 /* dma tx transaction in progress */

	bool rx_dma_busy;	 /* dma rx transaction in progress */

	bool throttled;		 /* port throttled            */

	bool hw_flow_control;

	bool swap;		 /* swap RX & TX pins */