spi: atmel: convert to dma_request_slave_channel_compat()

Use generic DMA DT helper.
Platforms booting with or without DT populated are both supported.

Based on Ludovic Desroches <ludovic.desroches@atmel.com> patchset
"ARM: at91: move to generic DMA device tree binding"

Signed-off-by: Richard Genoud <richard.genoud@gmail.com>
Acked-by: Ludovic Desroches <ludovic.desroches@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/spi/spi-atmel.c

@@ -424,10 +424,15 @@ static int atmel_spi_dma_slave_config(struct atmel_spi *as,
 	return err;
 }
 
-static bool filter(struct dma_chan *chan, void *slave)
+static bool filter(struct dma_chan *chan, void *pdata)
 {
-	struct	at_dma_slave *sl = slave;
+	struct atmel_spi_dma *sl_pdata = pdata;
+	struct at_dma_slave *sl;
 
+	if (!sl_pdata)
+		return false;
+
+	sl = &sl_pdata->dma_slave;
 	if (sl->dma_dev == chan->device->dev) {
 		chan->private = sl;
 		return true;
@@ -438,24 +443,31 @@ static bool filter(struct dma_chan *chan, void *slave)
 
 static int atmel_spi_configure_dma(struct atmel_spi *as)
 {
-	struct at_dma_slave *sdata = &as->dma.dma_slave;
 	struct dma_slave_config	slave_config;
+	struct device *dev = &as->pdev->dev;
 	int err;
 
-	if (sdata && sdata->dma_dev) {
-		dma_cap_mask_t mask;
+	dma_cap_mask_t mask;
+	dma_cap_zero(mask);
+	dma_cap_set(DMA_SLAVE, mask);
 
-		/* Try to grab two DMA channels */
-		dma_cap_zero(mask);
-		dma_cap_set(DMA_SLAVE, mask);
-		as->dma.chan_tx = dma_request_channel(mask, filter, sdata);
-		if (as->dma.chan_tx)
-			as->dma.chan_rx =
-				dma_request_channel(mask, filter, sdata);
+	as->dma.chan_tx = dma_request_slave_channel_compat(mask, filter,
+							   &as->dma,
+							   dev, "tx");
+	if (!as->dma.chan_tx) {
+		dev_err(dev,
+			"DMA TX channel not available, SPI unable to use DMA\n");
+		err = -EBUSY;
+		goto error;
 	}
-	if (!as->dma.chan_rx || !as->dma.chan_tx) {
-		dev_err(&as->pdev->dev,
-			"DMA channel not available, SPI unable to use DMA\n");
+
+	as->dma.chan_rx = dma_request_slave_channel_compat(mask, filter,
+							   &as->dma,
+							   dev, "rx");
+
+	if (!as->dma.chan_rx) {
+		dev_err(dev,
+			"DMA RX channel not available, SPI unable to use DMA\n");
 		err = -EBUSY;
 		goto error;
 	}