Blackfin SPI Driver: pass DMA overflow error to the higher level

If the SPI bus registers a receive overflow error, pass the result back up
to the higher levels.
Signed-off-by: NMike Frysinger <vapier.adi@gmail.com>
Signed-off-by: NBryan Wu <cooloney@kernel.org>
Acked-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/spi/spi_bfin5xx.c

@@ -559,6 +559,7 @@ static irqreturn_t dma_irq_handler(int irq, void *dev_id)
 	struct driver_data *drv_data = dev_id;
 	struct chip_data *chip = drv_data->cur_chip;
 	struct spi_message *msg = drv_data->cur_msg;
+	u16 spistat = read_STAT(drv_data);
 
 	dev_dbg(&drv_data->pdev->dev, "in dma_irq_handler\n");
 	clear_dma_irqstat(drv_data->dma_channel);
@@ -582,13 +583,18 @@ static irqreturn_t dma_irq_handler(int irq, void *dev_id)
 	while (!(read_STAT(drv_data) & SPIF))
 		cpu_relax();
 
-	msg->actual_length += drv_data->len_in_bytes;
+	if (spistat & RBSY) {
+		msg->state = ERROR_STATE;
+		dev_err(&drv_data->pdev->dev, "dma receive: fifo/buffer overflow\n");
+	} else {
+		msg->actual_length += drv_data->len_in_bytes;
 
-	if (drv_data->cs_change)
-		cs_deactive(drv_data, chip);
+		if (drv_data->cs_change)
+			cs_deactive(drv_data, chip);
 
-	/* Move to next transfer */
-	msg->state = next_transfer(drv_data);
+		/* Move to next transfer */
+		msg->state = next_transfer(drv_data);
+	}
 
 	/* Schedule transfer tasklet */
 	tasklet_schedule(&drv_data->pump_transfers);