[PATCH 13/15] tty: atmel_serial: use single DMA mapping for TX

[PATCH 13/15] tty: atmel_serial: use single DMA mapping for TX

[Jiri Slaby (SUSE)]

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: Jiri 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
---
 drivers/tty/serial/atmel_serial.c | 35 +++++++++++++------------------
 1 file changed, 14 insertions(+), 21 deletions(-)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 5bb5e4303754..69ec80ffc97b 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -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 */
-- 
2.44.0


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[PATCH 14/15] tty: atmel_serial: define macro for RX size

[Jiri Slaby (SUSE)]

It is repeated in the code and there is also a big warning by
ATMEL_SERIAL_RINGSIZE. So define ATMEL_SERIAL_RX_SIZE and use it
appropriatelly.

The macro uses array_size() and kmalloc_array() is switched to
kmalloc().

Signed-off-by: Jiri 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
---
 drivers/tty/serial/atmel_serial.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 69ec80ffc97b..5cde5077c429 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -96,7 +96,9 @@ struct atmel_uart_char {
  * can contain up to 1024 characters in PIO mode and up to 4096 characters in
  * DMA mode.
  */
-#define ATMEL_SERIAL_RINGSIZE 1024
+#define ATMEL_SERIAL_RINGSIZE	1024
+#define ATMEL_SERIAL_RX_SIZE	array_size(sizeof(struct atmel_uart_char), \
+					   ATMEL_SERIAL_RINGSIZE)
 
 /*
  * at91: 6 USARTs and one DBGU port (SAM9260)
@@ -1208,7 +1210,7 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
 	BUG_ON(!PAGE_ALIGNED(ring->buf));
 	sg_set_page(&atmel_port->sg_rx,
 		    virt_to_page(ring->buf),
-		    sizeof(struct atmel_uart_char) * ATMEL_SERIAL_RINGSIZE,
+		    ATMEL_SERIAL_RX_SIZE,
 		    offset_in_page(ring->buf));
 	nent = dma_map_sg(port->dev,
 			  &atmel_port->sg_rx,
@@ -2947,9 +2949,7 @@ static int atmel_serial_probe(struct platform_device *pdev)
 
 	if (!atmel_use_pdc_rx(&atmel_port->uart)) {
 		ret = -ENOMEM;
-		data = kmalloc_array(ATMEL_SERIAL_RINGSIZE,
-				     sizeof(struct atmel_uart_char),
-				     GFP_KERNEL);
+		data = kmalloc(ATMEL_SERIAL_RX_SIZE, GFP_KERNEL);
 		if (!data)
 			goto err_clk_disable_unprepare;
 		atmel_port->rx_ring.buf = data;
-- 
2.44.0


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[PATCH 15/15] tty: atmel_serial: use single DMA mapping for RX

[Jiri Slaby (SUSE)]

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: Jiri 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
---
 drivers/tty/serial/atmel_serial.c | 56 ++++++++++++-------------------
 1 file changed, 22 insertions(+), 34 deletions(-)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 5cde5077c429..0a90964d6d10 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -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_SERIAL_RX_SIZE,
-		    offset_in_page(ring->buf));
-	nent = dma_map_sg(port->dev,
-			  &atmel_port->sg_rx,
-			  1,
-			  DMA_FROM_DEVICE);
-
-	if (!nent) {
+	atmel_port->rx_phys = dma_map_single(port->dev, ring->buf,
+					     ATMEL_SERIAL_RX_SIZE,
+					     DMA_FROM_DEVICE);
+
+	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) {
-- 
2.44.0


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