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Message-ID: <20240405060826.2521-16-jirislaby@kernel.org>
Date: Fri, 5 Apr 2024 08:08:26 +0200
From: "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
To: gregkh@...uxfoundation.org
Cc: linux-serial@...r.kernel.org,
linux-kernel@...r.kernel.org,
"Jiri Slaby (SUSE)" <jirislaby@...nel.org>,
Richard Genoud <richard.genoud@...il.com>,
Nicolas Ferre <nicolas.ferre@...rochip.com>,
Alexandre Belloni <alexandre.belloni@...tlin.com>,
Claudiu Beznea <claudiu.beznea@...on.dev>,
linux-arm-kernel@...ts.infradead.org
Subject: [PATCH 15/15] 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: Jiri Slaby (SUSE) <jirislaby@...nel.org>
Cc: Richard Genoud <richard.genoud@...il.com>
Cc: Nicolas Ferre <nicolas.ferre@...rochip.com>
Cc: Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc: Claudiu Beznea <claudiu.beznea@...on.dev>
Cc: linux-arm-kernel@...ts.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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