spi: pl022: use generic DMA slave configuration if possible

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@arndb.de>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Cc: spi-devel-general@lists.sourceforge.net
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Vinod Koul <vinod.koul@linux.intel.com>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: linux-arm-kernel@lists.infradead.org

1 files changed, 41 insertions, 2 deletions

diff --git a/drivers/spi/spi-pl022.c b/drivers/spi/spi-pl022.c
index b0fe393c882c..371cc66f1a0e 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;