serial: 8250: Extract IIR logic steering from rx dma

Using fake IIR values to perform rx dma operations unnecessarily
conflates separate operations, stopping in-progress dma with starting
new dma.

Introduce serial8250_rx_dma_flush() to handle stopping in-progress dma
[omap8250 already has equivalent omap_8250_rx_dma_flush()].
Replace rx_dma(UART_IIR_RX_TIMEOUT) with the equivalent *_rx_dma_flush(),
and rx_dma(0) with the equivalent *_rx_dma(). Handle IIR steering
in the irq handler with handle_rx_dma() helper.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 12 insertions, 20 deletions

diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c
index 7a26c4d13b18..7f33d1c8d1a9 100644
--- a/drivers/tty/serial/8250/8250_dma.c
+++ b/drivers/tty/serial/8250/8250_dma.c
@@ -110,30 +110,11 @@ err:
 	return ret;
 }
 
-int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
+int serial8250_rx_dma(struct uart_8250_port *p)
 {
 	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 */
-		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_complete(p);
-			dmaengine_terminate_all(dma->rxchan);
-		}
-		return -ETIMEDOUT;
-	default:
-		break;
-	}
-
 	if (dma->rx_running)
 		return 0;
 
@@ -154,6 +135,17 @@ int serial8250_rx_dma(struct uart_8250_port *p, unsigned int iir)
 	return 0;
 }
 
+void serial8250_rx_dma_flush(struct uart_8250_port *p)
+{
+	struct uart_8250_dma *dma = p->dma;
+
+	if (dma->rx_running) {
+		dmaengine_pause(dma->rxchan);
+		__dma_rx_complete(p);
+		dmaengine_terminate_all(dma->rxchan);
+	}
+}
+
 int serial8250_request_dma(struct uart_8250_port *p)
 {
 	struct uart_8250_dma	*dma = p->dma;