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serial: sh-sci: Switch to dma_map_single() for DMA transmission 

Simplify the DMA transmit code by using dma_map_single() instead of
constantly modifying the single-entry scatterlist to match what's
currently being transmitted.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Geert Uytterhoeven 2015-08-21 20:02:42 +02:00 committed by Greg Kroah-Hartman
parent 092248aa32
commit 79904420b7
1 changed files with 20 additions and 30 deletions
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50
drivers/tty/serial/sh-sci.c
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@ -109,8 +109,8 @@ struct sci_port {
dma_cookie_t cookie_tx;
dma_cookie_t cookie_rx[2];
dma_cookie_t active_rx;
struct scatterlist sg_tx;
unsigned int sg_len_tx;
dma_addr_t tx_dma_addr;
unsigned int tx_dma_len;
struct scatterlist sg_rx[2];
size_t buf_len_rx;
struct sh_dmae_slave param_tx;
@ -1280,10 +1280,10 @@ static void sci_dma_tx_complete(void *arg)
spin_lock_irqsave(&port->lock, flags);
xmit->tail += sg_dma_len(&s->sg_tx);
xmit->tail += s->tx_dma_len;
xmit->tail &= UART_XMIT_SIZE - 1;
port->icount.tx += sg_dma_len(&s->sg_tx);
port->icount.tx += s->tx_dma_len;
async_tx_ack(s->desc_tx);
s->desc_tx = NULL;
@ -1494,7 +1494,7 @@ static void work_fn_tx(struct work_struct *work)
struct dma_chan *chan = s->chan_tx;
struct uart_port *port = &s->port;
struct circ_buf *xmit = &port->state->xmit;
struct scatterlist *sg = &s->sg_tx;
dma_addr_t buf;
/*
* DMA is idle now.
@ -1504,19 +1504,15 @@ static void work_fn_tx(struct work_struct *work)
* consistent xmit buffer state.
*/
spin_lock_irq(&port->lock);
sg->offset = xmit->tail & (UART_XMIT_SIZE - 1);
sg_dma_address(sg) = (sg_dma_address(sg) & ~(UART_XMIT_SIZE - 1)) +
sg->offset;
sg_dma_len(sg) = min_t(unsigned int,
buf = s->tx_dma_addr + (xmit->tail & (UART_XMIT_SIZE - 1));
s->tx_dma_len = min_t(unsigned int,
CIRC_CNT(xmit->head, xmit->tail, UART_XMIT_SIZE),
CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE));
spin_unlock_irq(&port->lock);
BUG_ON(!sg_dma_len(sg));
desc = dmaengine_prep_slave_sg(chan,
sg, s->sg_len_tx, DMA_MEM_TO_DEV,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
desc = dmaengine_prep_slave_single(chan, buf, s->tx_dma_len,
DMA_MEM_TO_DEV,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc) {
dev_warn(port->dev, "Failed preparing Tx DMA descriptor\n");
/* switch to PIO */
@ -1524,7 +1520,8 @@ static void work_fn_tx(struct work_struct *work)
return;
}
dma_sync_sg_for_device(chan->device->dev, sg, 1, DMA_TO_DEVICE);
dma_sync_single_for_device(chan->device->dev, buf, s->tx_dma_len,
DMA_TO_DEVICE);
spin_lock_irq(&port->lock);
s->desc_tx = desc;
@ -1680,7 +1677,6 @@ static void sci_request_dma(struct uart_port *port)
struct sh_dmae_slave *param;
struct dma_chan *chan;
dma_cap_mask_t mask;
int nent;
dev_dbg(port->dev, "%s: port %d\n", __func__, port->line);
@ -1700,27 +1696,21 @@ static void sci_request_dma(struct uart_port *port)
dev_dbg(port->dev, "%s: TX: got channel %p\n", __func__, chan);
if (chan) {
s->chan_tx = chan;
sg_init_table(&s->sg_tx, 1);
/* UART circular tx buffer is an aligned page. */
BUG_ON((uintptr_t)port->state->xmit.buf & ~PAGE_MASK);
sg_set_page(&s->sg_tx, virt_to_page(port->state->xmit.buf),
UART_XMIT_SIZE,
(uintptr_t)port->state->xmit.buf & ~PAGE_MASK);
nent = dma_map_sg(chan->device->dev, &s->sg_tx, 1,
DMA_TO_DEVICE);
if (!nent) {
s->tx_dma_addr = dma_map_single(chan->device->dev,
port->state->xmit.buf,
UART_XMIT_SIZE,
DMA_TO_DEVICE);
if (dma_mapping_error(chan->device->dev, s->tx_dma_addr)) {
dev_warn(port->dev, "Failed mapping Tx DMA descriptor\n");
dma_release_channel(chan);
s->chan_tx = NULL;
} else {
dev_dbg(port->dev, "%s: mapped %d@%p to %pad\n",
__func__,
sg_dma_len(&s->sg_tx), port->state->xmit.buf,
&sg_dma_address(&s->sg_tx));
dev_dbg(port->dev, "%s: mapped %lu@%p to %pad\n",
__func__, UART_XMIT_SIZE,
port->state->xmit.buf, &s->tx_dma_addr);
}
s->sg_len_tx = nent;
INIT_WORK(&s->work_tx, work_fn_tx);
}