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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: 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/20240405060826.2521-16-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -135,7 +135,7 @@ struct atmel_uart_port {
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dma_cookie_t cookie_tx;
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dma_cookie_t cookie_rx;
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dma_addr_t tx_phys;
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struct scatterlist sg_rx;
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dma_addr_t rx_phys;
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struct tasklet_struct tasklet_rx;
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struct tasklet_struct tasklet_tx;
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atomic_t tasklet_shutdown;
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@ -1088,8 +1088,8 @@ static void atmel_release_rx_dma(struct uart_port *port)
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if (chan) {
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dmaengine_terminate_all(chan);
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dma_release_channel(chan);
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dma_unmap_sg(port->dev, &atmel_port->sg_rx, 1,
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DMA_FROM_DEVICE);
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dma_unmap_single(port->dev, atmel_port->rx_phys,
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ATMEL_SERIAL_RX_SIZE, DMA_FROM_DEVICE);
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}
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atmel_port->desc_rx = NULL;
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@ -1122,10 +1122,8 @@ static void atmel_rx_from_dma(struct uart_port *port)
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}
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/* CPU claims ownership of RX DMA buffer */
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dma_sync_sg_for_cpu(port->dev,
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&atmel_port->sg_rx,
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1,
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DMA_FROM_DEVICE);
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dma_sync_single_for_cpu(port->dev, atmel_port->rx_phys,
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ATMEL_SERIAL_RX_SIZE, DMA_FROM_DEVICE);
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/*
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* ring->head points to the end of data already written by the DMA.
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@ -1134,8 +1132,8 @@ static void atmel_rx_from_dma(struct uart_port *port)
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* The current transfer size should not be larger than the dma buffer
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* length.
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*/
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ring->head = sg_dma_len(&atmel_port->sg_rx) - state.residue;
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BUG_ON(ring->head > sg_dma_len(&atmel_port->sg_rx));
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ring->head = ATMEL_SERIAL_RX_SIZE - state.residue;
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BUG_ON(ring->head > ATMEL_SERIAL_RX_SIZE);
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/*
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* At this point ring->head may point to the first byte right after the
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* last byte of the dma buffer:
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@ -1149,7 +1147,7 @@ static void atmel_rx_from_dma(struct uart_port *port)
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* tail to the end of the buffer then reset tail.
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*/
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if (ring->head < ring->tail) {
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count = sg_dma_len(&atmel_port->sg_rx) - ring->tail;
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count = ATMEL_SERIAL_RX_SIZE - ring->tail;
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tty_insert_flip_string(tport, ring->buf + ring->tail, count);
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ring->tail = 0;
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@ -1162,17 +1160,15 @@ static void atmel_rx_from_dma(struct uart_port *port)
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tty_insert_flip_string(tport, ring->buf + ring->tail, count);
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/* Wrap ring->head if needed */
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if (ring->head >= sg_dma_len(&atmel_port->sg_rx))
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if (ring->head >= ATMEL_SERIAL_RX_SIZE)
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ring->head = 0;
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ring->tail = ring->head;
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port->icount.rx += count;
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}
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/* USART retreives ownership of RX DMA buffer */
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dma_sync_sg_for_device(port->dev,
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&atmel_port->sg_rx,
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1,
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DMA_FROM_DEVICE);
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dma_sync_single_for_device(port->dev, atmel_port->rx_phys,
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ATMEL_SERIAL_RX_SIZE, DMA_FROM_DEVICE);
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tty_flip_buffer_push(tport);
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@ -1188,7 +1184,7 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
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struct dma_slave_config config;
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struct circ_buf *ring;
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struct dma_chan *chan;
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int ret, nent;
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int ret;
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ring = &atmel_port->rx_ring;
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@ -1205,26 +1201,18 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
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dma_chan_name(atmel_port->chan_rx));
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spin_lock_init(&atmel_port->lock_rx);
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sg_init_table(&atmel_port->sg_rx, 1);
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/* UART circular rx buffer is an aligned page. */
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BUG_ON(!PAGE_ALIGNED(ring->buf));
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sg_set_page(&atmel_port->sg_rx,
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virt_to_page(ring->buf),
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ATMEL_SERIAL_RX_SIZE,
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offset_in_page(ring->buf));
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nent = dma_map_sg(port->dev,
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&atmel_port->sg_rx,
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1,
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DMA_FROM_DEVICE);
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atmel_port->rx_phys = dma_map_single(port->dev, ring->buf,
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ATMEL_SERIAL_RX_SIZE,
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DMA_FROM_DEVICE);
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if (!nent) {
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if (dma_mapping_error(port->dev, atmel_port->rx_phys)) {
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dev_dbg(port->dev, "need to release resource of dma\n");
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goto chan_err;
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} else {
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dev_dbg(port->dev, "%s: mapped %d@%p to %pad\n", __func__,
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sg_dma_len(&atmel_port->sg_rx),
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ring->buf,
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&sg_dma_address(&atmel_port->sg_rx));
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dev_dbg(port->dev, "%s: mapped %zu@%p to %pad\n", __func__,
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ATMEL_SERIAL_RX_SIZE, ring->buf, &atmel_port->rx_phys);
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}
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/* Configure the slave DMA */
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@ -1245,9 +1233,9 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
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* each one is half ring buffer size
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*/
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desc = dmaengine_prep_dma_cyclic(atmel_port->chan_rx,
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sg_dma_address(&atmel_port->sg_rx),
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sg_dma_len(&atmel_port->sg_rx),
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sg_dma_len(&atmel_port->sg_rx)/2,
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atmel_port->rx_phys,
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ATMEL_SERIAL_RX_SIZE,
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ATMEL_SERIAL_RX_SIZE / 2,
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DMA_DEV_TO_MEM,
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DMA_PREP_INTERRUPT);
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if (!desc) {
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