Commit e51c3e1d authored by Jiri Slaby (SUSE)'s avatar Jiri Slaby (SUSE) Committed by Greg Kroah-Hartman
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tty: atmel_serial: use single DMA mapping for RX 



dma_map_single() provides much easier interface for simple mappings as
used for RX in atmel_serial. So switch to that, removing all the s-g
unnecessary handling.

Signed-off-by: default avatarJiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Richard Genoud <richard.genoud@gmail.com>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Claudiu Beznea <claudiu.beznea@tuxon.dev>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20240405060826.2521-16-jirislaby@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 12bedddb

drivers/tty/serial/atmel_serial.c

+22 −34
Original line number Diff line number Diff line
@@ -135,7 +135,7 @@ struct atmel_uart_port { 
	dma_cookie_t			cookie_tx;

	dma_cookie_t			cookie_rx;

	dma_addr_t			tx_phys;

	struct scatterlist		sg_rx;

	dma_addr_t			rx_phys;

	struct tasklet_struct	tasklet_rx;

	struct tasklet_struct	tasklet_tx;

	atomic_t		tasklet_shutdown;
@@ -1088,8 +1088,8 @@ static void atmel_release_rx_dma(struct uart_port *port) 
	if (chan) {

		dmaengine_terminate_all(chan);

		dma_release_channel(chan);

		dma_unmap_sg(port->dev, &atmel_port->sg_rx, 1,

				DMA_FROM_DEVICE);

		dma_unmap_single(port->dev, atmel_port->rx_phys,

				 ATMEL_SERIAL_RX_SIZE, DMA_FROM_DEVICE);

	}



	atmel_port->desc_rx = NULL;
@@ -1122,10 +1122,8 @@ static void atmel_rx_from_dma(struct uart_port *port) 
	}



	/* CPU claims ownership of RX DMA buffer */

	dma_sync_sg_for_cpu(port->dev,

			    &atmel_port->sg_rx,

			    1,

			    DMA_FROM_DEVICE);

	dma_sync_single_for_cpu(port->dev, atmel_port->rx_phys,

				ATMEL_SERIAL_RX_SIZE, DMA_FROM_DEVICE);



	/*

	 * ring->head points to the end of data already written by the DMA.
@@ -1134,8 +1132,8 @@ static void atmel_rx_from_dma(struct uart_port *port) 
	 * The current transfer size should not be larger than the dma buffer

	 * length.

	 */

	ring->head = sg_dma_len(&atmel_port->sg_rx) - state.residue;

	BUG_ON(ring->head > sg_dma_len(&atmel_port->sg_rx));

	ring->head = ATMEL_SERIAL_RX_SIZE - state.residue;

	BUG_ON(ring->head > ATMEL_SERIAL_RX_SIZE);

	/*

	 * At this point ring->head may point to the first byte right after the

	 * last byte of the dma buffer:
@@ -1149,7 +1147,7 @@ static void atmel_rx_from_dma(struct uart_port *port) 
	 * tail to the end of the buffer then reset tail.

	 */

	if (ring->head < ring->tail) {

		count = sg_dma_len(&atmel_port->sg_rx) - ring->tail;

		count = ATMEL_SERIAL_RX_SIZE - ring->tail;



		tty_insert_flip_string(tport, ring->buf + ring->tail, count);

		ring->tail = 0;
@@ -1162,17 +1160,15 @@ static void atmel_rx_from_dma(struct uart_port *port) 


		tty_insert_flip_string(tport, ring->buf + ring->tail, count);

		/* Wrap ring->head if needed */

		if (ring->head >= sg_dma_len(&atmel_port->sg_rx))

		if (ring->head >= ATMEL_SERIAL_RX_SIZE)

			ring->head = 0;

		ring->tail = ring->head;

		port->icount.rx += count;

	}



	/* USART retreives ownership of RX DMA buffer */

	dma_sync_sg_for_device(port->dev,

			       &atmel_port->sg_rx,

			       1,

			       DMA_FROM_DEVICE);

	dma_sync_single_for_device(port->dev, atmel_port->rx_phys,

				   ATMEL_SERIAL_RX_SIZE, DMA_FROM_DEVICE);



	tty_flip_buffer_push(tport);
@@ -1188,7 +1184,7 @@ static int atmel_prepare_rx_dma(struct uart_port *port) 
	struct dma_slave_config config;

	struct circ_buf		*ring;

	struct dma_chan *chan;

	int ret, nent;

	int ret;



	ring = &atmel_port->rx_ring;
@@ -1205,26 +1201,18 @@ static int atmel_prepare_rx_dma(struct uart_port *port) 
		dma_chan_name(atmel_port->chan_rx));



	spin_lock_init(&atmel_port->lock_rx);

	sg_init_table(&atmel_port->sg_rx, 1);

	/* UART circular rx buffer is an aligned page. */

	BUG_ON(!PAGE_ALIGNED(ring->buf));

	sg_set_page(&atmel_port->sg_rx,

		    virt_to_page(ring->buf),

	atmel_port->rx_phys = dma_map_single(port->dev, ring->buf,

					     ATMEL_SERIAL_RX_SIZE,

		    offset_in_page(ring->buf));

	nent = dma_map_sg(port->dev,

			  &atmel_port->sg_rx,

			  1,

					     DMA_FROM_DEVICE);



	if (!nent) {

	if (dma_mapping_error(port->dev, atmel_port->rx_phys)) {

		dev_dbg(port->dev, "need to release resource of dma\n");

		goto chan_err;

	} else {

		dev_dbg(port->dev, "%s: mapped %d@%p to %pad\n", __func__,

			sg_dma_len(&atmel_port->sg_rx),

			ring->buf,

			&sg_dma_address(&atmel_port->sg_rx));

		dev_dbg(port->dev, "%s: mapped %zu@%p to %pad\n", __func__,

			ATMEL_SERIAL_RX_SIZE, ring->buf, &atmel_port->rx_phys);

	}



	/* Configure the slave DMA */
@@ -1245,9 +1233,9 @@ static int atmel_prepare_rx_dma(struct uart_port *port) 
	 * each one is half ring buffer size

	 */

	desc = dmaengine_prep_dma_cyclic(atmel_port->chan_rx,

					 sg_dma_address(&atmel_port->sg_rx),

					 sg_dma_len(&atmel_port->sg_rx),

					 sg_dma_len(&atmel_port->sg_rx)/2,

					 atmel_port->rx_phys,

					 ATMEL_SERIAL_RX_SIZE,

					 ATMEL_SERIAL_RX_SIZE / 2,

					 DMA_DEV_TO_MEM,

					 DMA_PREP_INTERRUPT);

	if (!desc) {