Commit b9cea51b 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 TX 



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

Note that it is not easy (maybe impossible) to use kfifo_dma_* API for
atmel's serial purposes. It handles DMA very specially.

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/20240405060826.2521-14-jirislaby@kernel.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1788cf6a

drivers/tty/serial/atmel_serial.c

+14 −21
Original line number Diff line number Diff line
@@ -132,7 +132,7 @@ struct atmel_uart_port { 
	struct dma_async_tx_descriptor	*desc_rx;

	dma_cookie_t			cookie_tx;

	dma_cookie_t			cookie_rx;

	struct scatterlist		sg_tx;

	dma_addr_t			tx_phys;

	struct scatterlist		sg_rx;

	struct tasklet_struct	tasklet_rx;

	struct tasklet_struct	tasklet_tx;
@@ -904,8 +904,8 @@ static void atmel_release_tx_dma(struct uart_port *port) 
	if (chan) {

		dmaengine_terminate_all(chan);

		dma_release_channel(chan);

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

				DMA_TO_DEVICE);

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

				 UART_XMIT_SIZE, DMA_TO_DEVICE);

	}



	atmel_port->desc_tx = NULL;
@@ -922,7 +922,7 @@ static void atmel_tx_dma(struct uart_port *port) 
	struct tty_port *tport = &port->state->port;

	struct dma_chan *chan = atmel_port->chan_tx;

	struct dma_async_tx_descriptor *desc;

	struct scatterlist sgl[2], *sg, *sg_tx = &atmel_port->sg_tx;

	struct scatterlist sgl[2], *sg;

	unsigned int tx_len, tail, part1_len, part2_len, sg_len;

	dma_addr_t phys_addr;
@@ -955,7 +955,7 @@ static void atmel_tx_dma(struct uart_port *port) 


		sg_init_table(sgl, 2);

		sg_len = 0;

		phys_addr = sg_dma_address(sg_tx) + tail;

		phys_addr = atmel_port->tx_phys + tail;

		if (part1_len) {

			sg = &sgl[sg_len++];

			sg_dma_address(sg) = phys_addr;
@@ -987,7 +987,8 @@ static void atmel_tx_dma(struct uart_port *port) 
			return;

		}



		dma_sync_sg_for_device(port->dev, sg_tx, 1, DMA_TO_DEVICE);

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

					   UART_XMIT_SIZE, DMA_TO_DEVICE);



		atmel_port->desc_tx = desc;

		desc->callback = atmel_complete_tx_dma;
@@ -1014,7 +1015,7 @@ static int atmel_prepare_tx_dma(struct uart_port *port) 
	dma_cap_mask_t		mask;

	struct dma_slave_config config;

	struct dma_chan *chan;

	int ret, nent;

	int ret;



	dma_cap_zero(mask);

	dma_cap_set(DMA_SLAVE, mask);
@@ -1029,26 +1030,18 @@ static int atmel_prepare_tx_dma(struct uart_port *port) 
		dma_chan_name(atmel_port->chan_tx));



	spin_lock_init(&atmel_port->lock_tx);

	sg_init_table(&atmel_port->sg_tx, 1);

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

	BUG_ON(!PAGE_ALIGNED(tport->xmit_buf));

	sg_set_page(&atmel_port->sg_tx,

			virt_to_page(tport->xmit_buf),

			UART_XMIT_SIZE,

			offset_in_page(tport->xmit_buf));

	nent = dma_map_sg(port->dev,

				&atmel_port->sg_tx,

				1,

				DMA_TO_DEVICE);

	atmel_port->tx_phys = dma_map_single(port->dev, tport->xmit_buf,

					     UART_XMIT_SIZE, DMA_TO_DEVICE);



	if (!nent) {

	if (dma_mapping_error(port->dev, atmel_port->tx_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_tx),

			tport->xmit_buf,

			&sg_dma_address(&atmel_port->sg_tx));

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

			UART_XMIT_SIZE, tport->xmit_buf,

			&atmel_port->tx_phys);

	}



	/* Configure the slave DMA */