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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: Robert Baldyga <r.baldyga@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Robert Baldyga 2014-12-10 12:49:25 +01:00 committed by Greg Kroah-Hartman
parent a291b7d5f6
commit 62c37eedb7
1 changed files with 101 additions and 0 deletions
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101
drivers/tty/serial/samsung.c
View File

@ -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);