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tty: serial: 8250_omap: add custom DMA-RX callback 

The omap needs a DMA request pending right away. If it is
enqueued once the bytes are in the FIFO then nothing will happen
and the FIFO will be later purged via RX-timeout interrupt.
This patch enqueues RX-DMA request on completion but not if it
was aborted on error. The first enqueue will happen in the driver
in startup.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sebastian Andrzej Siewior 2014-09-29 20:06:44 +02:00 committed by Greg Kroah-Hartman
parent 31a171328e
commit 0e31c8d173
1 changed files with 96 additions and 0 deletions
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96
drivers/tty/serial/8250/8250_omap.c
View File

@ -619,6 +619,102 @@ static void omap_8250_unthrottle(struct uart_port *port)
}
#ifdef CONFIG_SERIAL_8250_DMA
static int omap_8250_rx_dma(struct uart_8250_port *p, unsigned int iir);
static void __dma_rx_do_complete(struct uart_8250_port *p, bool error)
{
struct uart_8250_dma *dma = p->dma;
struct tty_port *tty_port = &p->port.state->port;
struct dma_tx_state state;
int count;
dma_sync_single_for_cpu(dma->rxchan->device->dev, dma->rx_addr,
dma->rx_size, DMA_FROM_DEVICE);
dma->rx_running = 0;
dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
dmaengine_terminate_all(dma->rxchan);
count = dma->rx_size - state.residue;
tty_insert_flip_string(tty_port, dma->rx_buf, count);
p->port.icount.rx += count;
if (!error)
omap_8250_rx_dma(p, 0);
tty_flip_buffer_push(tty_port);
}
static void __dma_rx_complete(void *param)
{
__dma_rx_do_complete(param, false);
}
static int omap_8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
{
struct uart_8250_dma *dma = p->dma;
struct dma_async_tx_descriptor *desc;
switch (iir & 0x3f) {
case UART_IIR_RLSI:
/* 8250_core handles errors and break interrupts */
if (dma->rx_running) {
dmaengine_pause(dma->rxchan);
__dma_rx_do_complete(p, true);
}
return -EIO;
case UART_IIR_RX_TIMEOUT:
/*
* If RCVR FIFO trigger level was not reached, complete the
* transfer and let 8250_core copy the remaining data.
*/
if (dma->rx_running) {
dmaengine_pause(dma->rxchan);
__dma_rx_do_complete(p, true);
}
return -ETIMEDOUT;
case UART_IIR_RDI:
/*
* The OMAP UART is a special BEAST. If we receive RDI we _have_
* a DMA transfer programmed but it didn't work. One reason is
* that we were too slow and there were too many bytes in the
* FIFO, the UART counted wrong and never kicked the DMA engine
* to do anything. That means once we receive RDI on OMAP then
* the DMA won't do anything soon so we have to cancel the DMA
* transfer and purge the FIFO manually.
*/
if (dma->rx_running) {
dmaengine_pause(dma->rxchan);
__dma_rx_do_complete(p, true);
}
return -ETIMEDOUT;
default:
break;
}
if (dma->rx_running)
return 0;
desc = dmaengine_prep_slave_single(dma->rxchan, dma->rx_addr,
dma->rx_size, DMA_DEV_TO_MEM,
DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
if (!desc)
return -EBUSY;
dma->rx_running = 1;
desc->callback = __dma_rx_complete;
desc->callback_param = p;
dma->rx_cookie = dmaengine_submit(desc);
dma_sync_single_for_device(dma->rxchan->device->dev, dma->rx_addr,
dma->rx_size, DMA_FROM_DEVICE);
dma_async_issue_pending(dma->rxchan);
return 0;
}
static int omap_8250_tx_dma(struct uart_8250_port *p);
static void omap_8250_dma_tx_complete(void *param)