Skip to content

Commit

Permalink
serial: fsl_lpuart: move DMA channel request to probe
Browse files Browse the repository at this point in the history 
Move the DMA channel request to probe to avoid requesting the DMA
channel on each opening of the ttyLPx device. This also fixes a
potential issue that TX channel is not freed when only RX channel
allocation fails. The DMA channels are now handled independently,
so one could use UART with DMA only in TX direction for instance.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  • Loading branch information
Stefan Agner authored and Greg Kroah-Hartman committed Feb 2, 2015
1 parent 5f1437f commit 4a818c4
Showing 1 changed file with 44 additions and 52 deletions.
96 changes: 44 additions & 52 deletions drivers/tty/serial/fsl_lpuart.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -237,7 +237,8 @@ struct lpuart_port {
unsigned int rxfifo_size;
bool lpuart32;

bool lpuart_dma_use;
bool lpuart_dma_tx_use;
bool lpuart_dma_rx_use;
struct dma_chan *dma_tx_chan;
struct dma_chan *dma_rx_chan;
struct dma_async_tx_descriptor *dma_tx_desc;
Expand Down Expand Up @@ -568,7 +569,7 @@ static void lpuart_start_tx(struct uart_port *port)
temp = readb(port->membase + UARTCR2);
writeb(temp | UARTCR2_TIE, port->membase + UARTCR2);

if (sport->lpuart_dma_use) {
if (sport->lpuart_dma_tx_use) {
if (!uart_circ_empty(xmit) && !sport->dma_tx_in_progress)
lpuart_prepare_tx(sport);
} else {
Expand Down Expand Up @@ -761,13 +762,13 @@ static irqreturn_t lpuart_int(int irq, void *dev_id)
crdma = readb(sport->port.membase + UARTCR5);

if (sts & UARTSR1_RDRF && !(crdma & UARTCR5_RDMAS)) {
if (sport->lpuart_dma_use)
if (sport->lpuart_dma_rx_use)
lpuart_prepare_rx(sport);
else
lpuart_rxint(irq, dev_id);
}
if (sts & UARTSR1_TDRE && !(crdma & UARTCR5_TDMAS)) {
if (sport->lpuart_dma_use)
if (sport->lpuart_dma_tx_use)
lpuart_pio_tx(sport);
else
lpuart_txint(irq, dev_id);
Expand Down Expand Up @@ -950,26 +951,17 @@ static int lpuart_dma_tx_request(struct uart_port *port)
{
struct lpuart_port *sport = container_of(port,
struct lpuart_port, port);
struct dma_chan *tx_chan;
struct dma_slave_config dma_tx_sconfig;
dma_addr_t dma_bus;
unsigned char *dma_buf;
int ret;

tx_chan = dma_request_slave_channel(sport->port.dev, "tx");

if (!tx_chan) {
dev_err(sport->port.dev, "Dma tx channel request failed!\n");
return -ENODEV;
}

dma_bus = dma_map_single(tx_chan->device->dev,
dma_bus = dma_map_single(sport->dma_tx_chan->device->dev,
sport->port.state->xmit.buf,
UART_XMIT_SIZE, DMA_TO_DEVICE);

if (dma_mapping_error(tx_chan->device->dev, dma_bus)) {
if (dma_mapping_error(sport->dma_tx_chan->device->dev, dma_bus)) {
dev_err(sport->port.dev, "dma_map_single tx failed\n");
dma_release_channel(tx_chan);
return -ENOMEM;
}

Expand All @@ -978,16 +970,14 @@ static int lpuart_dma_tx_request(struct uart_port *port)
dma_tx_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
dma_tx_sconfig.dst_maxburst = sport->txfifo_size;
dma_tx_sconfig.direction = DMA_MEM_TO_DEV;
ret = dmaengine_slave_config(tx_chan, &dma_tx_sconfig);
ret = dmaengine_slave_config(sport->dma_tx_chan, &dma_tx_sconfig);

if (ret < 0) {
dev_err(sport->port.dev,
"Dma slave config failed, err = %d\n", ret);
dma_release_channel(tx_chan);
return ret;
}

sport->dma_tx_chan = tx_chan;
sport->dma_tx_buf_virt = dma_buf;
sport->dma_tx_buf_bus = dma_bus;
sport->dma_tx_in_progress = 0;
Expand All @@ -999,51 +989,39 @@ static int lpuart_dma_rx_request(struct uart_port *port)
{
struct lpuart_port *sport = container_of(port,
struct lpuart_port, port);
struct dma_chan *rx_chan;
struct dma_slave_config dma_rx_sconfig;
dma_addr_t dma_bus;
unsigned char *dma_buf;
int ret;

rx_chan = dma_request_slave_channel(sport->port.dev, "rx");

if (!rx_chan) {
dev_err(sport->port.dev, "Dma rx channel request failed!\n");
return -ENODEV;
}

dma_buf = devm_kzalloc(sport->port.dev,
FSL_UART_RX_DMA_BUFFER_SIZE, GFP_KERNEL);

if (!dma_buf) {
dev_err(sport->port.dev, "Dma rx alloc failed\n");
dma_release_channel(rx_chan);
return -ENOMEM;
}

dma_bus = dma_map_single(rx_chan->device->dev, dma_buf,
dma_bus = dma_map_single(sport->dma_rx_chan->device->dev, dma_buf,
FSL_UART_RX_DMA_BUFFER_SIZE, DMA_FROM_DEVICE);

if (dma_mapping_error(rx_chan->device->dev, dma_bus)) {
if (dma_mapping_error(sport->dma_rx_chan->device->dev, dma_bus)) {
dev_err(sport->port.dev, "dma_map_single rx failed\n");
dma_release_channel(rx_chan);
return -ENOMEM;
}

dma_rx_sconfig.src_addr = sport->port.mapbase + UARTDR;
dma_rx_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
dma_rx_sconfig.src_maxburst = 1;
dma_rx_sconfig.direction = DMA_DEV_TO_MEM;
ret = dmaengine_slave_config(rx_chan, &dma_rx_sconfig);
ret = dmaengine_slave_config(sport->dma_rx_chan, &dma_rx_sconfig);

if (ret < 0) {
dev_err(sport->port.dev,
"Dma slave config failed, err = %d\n", ret);
dma_release_channel(rx_chan);
return ret;
}

sport->dma_rx_chan = rx_chan;
sport->dma_rx_buf_virt = dma_buf;
sport->dma_rx_buf_bus = dma_bus;
sport->dma_rx_in_progress = 0;
Expand All @@ -1055,31 +1033,24 @@ static void lpuart_dma_tx_free(struct uart_port *port)
{
struct lpuart_port *sport = container_of(port,
struct lpuart_port, port);
struct dma_chan *dma_chan;

dma_unmap_single(sport->port.dev, sport->dma_tx_buf_bus,
UART_XMIT_SIZE, DMA_TO_DEVICE);
dma_chan = sport->dma_tx_chan;
sport->dma_tx_chan = NULL;

sport->dma_tx_buf_bus = 0;
sport->dma_tx_buf_virt = NULL;
dma_release_channel(dma_chan);
}

static void lpuart_dma_rx_free(struct uart_port *port)
{
struct lpuart_port *sport = container_of(port,
struct lpuart_port, port);
struct dma_chan *dma_chan;

dma_unmap_single(sport->port.dev, sport->dma_rx_buf_bus,
FSL_UART_RX_DMA_BUFFER_SIZE, DMA_FROM_DEVICE);

dma_chan = sport->dma_rx_chan;
sport->dma_rx_chan = NULL;
sport->dma_rx_buf_bus = 0;
sport->dma_rx_buf_virt = NULL;
dma_release_channel(dma_chan);
}

static int lpuart_startup(struct uart_port *port)
Expand All @@ -1098,17 +1069,21 @@ static int lpuart_startup(struct uart_port *port)
sport->rxfifo_size = 0x1 << (((temp >> UARTPFIFO_RXSIZE_OFF) &
UARTPFIFO_FIFOSIZE_MASK) + 1);

/* Whether use dma support by dma request results */
if (lpuart_dma_tx_request(port) || lpuart_dma_rx_request(port)) {
sport->lpuart_dma_use = false;
} else {
sport->lpuart_dma_use = true;
if (sport->dma_rx_chan && !lpuart_dma_rx_request(port)) {
sport->lpuart_dma_rx_use = true;
setup_timer(&sport->lpuart_timer, lpuart_timer_func,
(unsigned long)sport);
} else
sport->lpuart_dma_rx_use = false;


if (sport->dma_tx_chan && !lpuart_dma_tx_request(port)) {
sport->lpuart_dma_tx_use = true;
temp = readb(port->membase + UARTCR5);
temp &= ~UARTCR5_RDMAS;
writeb(temp | UARTCR5_TDMAS, port->membase + UARTCR5);
}
} else
sport->lpuart_dma_tx_use = false;

ret = devm_request_irq(port->dev, port->irq, lpuart_int, 0,
DRIVER_NAME, sport);
Expand Down Expand Up @@ -1179,12 +1154,13 @@ static void lpuart_shutdown(struct uart_port *port)

devm_free_irq(port->dev, port->irq, sport);

if (sport->lpuart_dma_use) {
if (sport->lpuart_dma_rx_use) {
lpuart_dma_rx_free(&sport->port);
del_timer_sync(&sport->lpuart_timer);

lpuart_dma_tx_free(port);
lpuart_dma_rx_free(port);
}

if (sport->lpuart_dma_tx_use)
lpuart_dma_tx_free(&sport->port);
}

static void lpuart32_shutdown(struct uart_port *port)
Expand Down Expand Up @@ -1306,7 +1282,7 @@ lpuart_set_termios(struct uart_port *port, struct ktermios *termios,
/* update the per-port timeout */
uart_update_timeout(port, termios->c_cflag, baud);

if (sport->lpuart_dma_use) {
if (sport->lpuart_dma_rx_use) {
/* Calculate delay for 1.5 DMA buffers */
sport->dma_rx_timeout = (sport->port.timeout - HZ / 50) *
FSL_UART_RX_DMA_BUFFER_SIZE * 3 /
Expand Down Expand Up @@ -1835,6 +1811,16 @@ static int lpuart_probe(struct platform_device *pdev)
return ret;
}

sport->dma_tx_chan = dma_request_slave_channel(sport->port.dev, "tx");
if (!sport->dma_tx_chan)
dev_info(sport->port.dev, "DMA tx channel request failed, "
"operating without tx DMA\n");

sport->dma_rx_chan = dma_request_slave_channel(sport->port.dev, "rx");
if (!sport->dma_rx_chan)
dev_info(sport->port.dev, "DMA rx channel request failed, "
"operating without rx DMA\n");

return 0;
}

Expand All @@ -1846,6 +1832,12 @@ static int lpuart_remove(struct platform_device *pdev)

clk_disable_unprepare(sport->clk);

if (sport->dma_tx_chan)
dma_release_channel(sport->dma_tx_chan);

if (sport->dma_rx_chan)
dma_release_channel(sport->dma_rx_chan);

return 0;
}

Expand Down

0 comments on commit 4a818c4

Please sign in to comment.