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tty: atmel_serial: use single DMA mapping for TX

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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
Link: https://lore.kernel.org/r/20240405060826.2521-14-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby (SUSE) 2024-04-05 08:08:24 +02:00 committed by Greg Kroah-Hartman
parent 1788cf6a91
commit b9cea51b65
1 changed files with 14 additions and 21 deletions
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35
drivers/tty/serial/atmel_serial.c
View File

@ -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 */