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Commit 62c37eed authored by Robert Baldyga's avatar Robert Baldyga Committed by Greg Kroah-Hartman
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serial: samsung: add dma reqest/release functions 



Add functions requesting and releasing RX and TX DMA channels. This
function are called only when "dmas" property in serial device-tree
node is defined.

Based on previous work of Sylwester Nawrocki and Lukasz Czerwinski.

Signed-off-by: default avatarRobert Baldyga <r.baldyga@samsung.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a291b7d5

drivers/tty/serial/samsung.c

+101 −0
Original line number Diff line number Diff line
@@ -28,6 +28,9 @@ 
#define SUPPORT_SYSRQ

#endif



#include <linux/dmaengine.h>

#include <linux/dma-mapping.h>

#include <linux/slab.h>

#include <linux/module.h>

#include <linux/ioport.h>

#include <linux/io.h>
@@ -453,6 +456,93 @@ static void s3c24xx_serial_break_ctl(struct uart_port *port, int break_state) 
	spin_unlock_irqrestore(&port->lock, flags);

}



static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)

{

	struct s3c24xx_uart_dma	*dma = p->dma;

	dma_cap_mask_t mask;

	unsigned long flags;



	/* Default slave configuration parameters */

	dma->rx_conf.direction		= DMA_DEV_TO_MEM;

	dma->rx_conf.src_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;

	dma->rx_conf.src_addr		= p->port.mapbase + S3C2410_URXH;

	dma->rx_conf.src_maxburst	= 16;



	dma->tx_conf.direction		= DMA_MEM_TO_DEV;

	dma->tx_conf.dst_addr_width	= DMA_SLAVE_BUSWIDTH_1_BYTE;

	dma->tx_conf.dst_addr		= p->port.mapbase + S3C2410_UTXH;

	if (dma_get_cache_alignment() >= 16)

		dma->tx_conf.dst_maxburst = 16;

	else

		dma->tx_conf.dst_maxburst = 1;



	dma_cap_zero(mask);

	dma_cap_set(DMA_SLAVE, mask);



	dma->rx_chan = dma_request_slave_channel_compat(mask, dma->fn,

					dma->rx_param, p->port.dev, "rx");

	if (!dma->rx_chan)

		return -ENODEV;



	dmaengine_slave_config(dma->rx_chan, &dma->rx_conf);



	dma->tx_chan = dma_request_slave_channel_compat(mask, dma->fn,

					dma->tx_param, p->port.dev, "tx");

	if (!dma->tx_chan) {

		dma_release_channel(dma->rx_chan);

		return -ENODEV;

	}



	dmaengine_slave_config(dma->tx_chan, &dma->tx_conf);



	/* RX buffer */

	dma->rx_size = PAGE_SIZE;



	dma->rx_buf = kmalloc(dma->rx_size, GFP_KERNEL);



	if (!dma->rx_buf) {

		dma_release_channel(dma->rx_chan);

		dma_release_channel(dma->tx_chan);

		return -ENOMEM;

	}



	dma->rx_addr = dma_map_single(dma->rx_chan->device->dev, dma->rx_buf,

				dma->rx_size, DMA_FROM_DEVICE);



	spin_lock_irqsave(&p->port.lock, flags);



	/* TX buffer */

	dma->tx_addr = dma_map_single(dma->tx_chan->device->dev,

				p->port.state->xmit.buf,

				UART_XMIT_SIZE, DMA_TO_DEVICE);



	spin_unlock_irqrestore(&p->port.lock, flags);



	return 0;

}



static void s3c24xx_serial_release_dma(struct s3c24xx_uart_port *p)

{

	struct s3c24xx_uart_dma	*dma = p->dma;



	if (dma->rx_chan) {

		dmaengine_terminate_all(dma->rx_chan);

		dma_unmap_single(dma->rx_chan->device->dev, dma->rx_addr,

				dma->rx_size, DMA_FROM_DEVICE);

		kfree(dma->rx_buf);

		dma_release_channel(dma->rx_chan);

		dma->rx_chan = NULL;

	}



	if (dma->tx_chan) {

		dmaengine_terminate_all(dma->tx_chan);

		dma_unmap_single(dma->tx_chan->device->dev, dma->tx_addr,

				UART_XMIT_SIZE, DMA_TO_DEVICE);

		dma_release_channel(dma->tx_chan);

		dma->tx_chan = NULL;

	}

}



static void s3c24xx_serial_shutdown(struct uart_port *port)

{

	struct s3c24xx_uart_port *ourport = to_ourport(port);
@@ -478,6 +568,10 @@ static void s3c24xx_serial_shutdown(struct uart_port *port) 
		wr_regl(port, S3C64XX_UINTP, 0xf);

		wr_regl(port, S3C64XX_UINTM, 0xf);

	}



	if (ourport->dma)

		s3c24xx_serial_release_dma(ourport);



}



static int s3c24xx_serial_startup(struct uart_port *port)
@@ -535,6 +629,13 @@ static int s3c64xx_serial_startup(struct uart_port *port) 
	    port, (unsigned long long)port->mapbase, port->membase);



	wr_regl(port, S3C64XX_UINTM, 0xf);

	if (ourport->dma) {

		ret = s3c24xx_serial_request_dma(ourport);

		if (ret < 0) {

			dev_warn(port->dev, "DMA request failed\n");

			return ret;

		}

	}



	ret = request_irq(port->irq, s3c64xx_serial_handle_irq, IRQF_SHARED,

			  s3c24xx_serial_portname(port), ourport);