[PATCH 2/5] spi: pl022: use generic DMA slave configuration if possible

[Arnd Bergmann]

With the new OF DMA binding, it is possible to completely avoid the
need for platform_data for configuring a DMA channel. In cases where the
platform has already been converted, calling dma_request_slave_channel
should get all the necessary information from the device tree.

Like the patch that converts the dw_dma controller, this is completely
untested and is looking for someone to try it out.

Signed-off-by: Arnd Bergmann <arnd at arndb.de>
Cc: Grant Likely <grant.likely at secretlab.ca>
Cc: Mark Brown <broonie at opensource.wolfsonmicro.com>
Cc: spi-devel-general at lists.sourceforge.net
Cc: Viresh Kumar <viresh.kumar at linaro.org>
Cc: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
Cc: Vinod Koul <vinod.koul at linux.intel.com>
Cc: devicetree-discuss at lists.ozlabs.org
Cc: linux-arm-kernel at vger.kernel.org
---
 drivers/spi/spi-pl022.c | 43 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 41 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-pl022.c b/drivers/spi/spi-pl022.c
index b0fe393..371cc66f 100644
--- a/drivers/spi/spi-pl022.c
+++ b/drivers/spi/spi-pl022.c
@@ -1139,6 +1139,35 @@ err_no_rxchan:
 	return -ENODEV;
 }
 
+static int pl022_dma_autoprobe(struct pl022 *pl022)
+{
+	struct device *dev = &pl022->adev->dev;
+
+	/* automatically configure DMA channels from platform, normally using DT */
+	pl022->dma_rx_channel = dma_request_slave_channel(dev, "rx");
+	if (!pl022->dma_rx_channel)
+		goto err_no_rxchan;
+
+	pl022->dma_tx_channel = dma_request_slave_channel(dev, "tx");
+	if (!pl022->dma_tx_channel)
+		goto err_no_txchan;
+
+	pl022->dummypage = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!pl022->dummypage)
+		goto err_no_dummypage;
+
+	return 0;
+
+err_no_dummypage:
+	dma_release_channel(pl022->dma_tx_channel);
+	pl022->dma_tx_channel = NULL;
+err_no_txchan:
+	dma_release_channel(pl022->dma_rx_channel);
+	pl022->dma_rx_channel = NULL;
+err_no_rxchan:
+	return -ENODEV;
+}
+		
 static void terminate_dma(struct pl022 *pl022)
 {
 	struct dma_chan *rxchan = pl022->dma_rx_channel;
@@ -1167,6 +1196,11 @@ static inline int configure_dma(struct pl022 *pl022)
 	return -ENODEV;
 }
 
+static inline int pl022_dma_autoprobe(struct pl022 *pl022)
+{
+	return 0;
+}
+
 static inline int pl022_dma_probe(struct pl022 *pl022)
 {
 	return 0;
@@ -2226,8 +2260,13 @@ static int pl022_probe(struct amba_device *adev, const struct amba_id *id)
 		goto err_no_irq;
 	}
 
-	/* Get DMA channels */
-	if (platform_info->enable_dma) {
+	/* Get DMA channels, try autoconfiguration first */
+	status = pl022_dma_autoprobe(pl022);
+
+	/* If that failed, use channels from platform_info */
+	if (status == 0)
+		platform_info->enable_dma = 1;
+	else if (platform_info->enable_dma) {
 		status = pl022_dma_probe(pl022);
 		if (status != 0)
 			platform_info->enable_dma = 0;
-- 
1.8.0