dmaengine: sun6i: Retrieve channel count/max request from devicetree

To avoid introduction of a new compatible for each small SoC/DMA controller
variation, move the definition of the channel count to the devicetree.

The number of vchans is no longer explicit, but limited by the highest
port/DMA request number. The result is a slight overallocation for SoCs
with a sparse port mapping.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
index 0cabb48..0cd13f1 100644 (file)
--- a/drivers/dma/sun6i-dma.c
+++ b/drivers/dma/sun6i-dma.c
@@ -42,6 +42,9 @@
 
 #define DMA_STAT               0x30
 
+/* Offset between DMA_IRQ_EN and DMA_IRQ_STAT limits number of channels */
+#define DMA_MAX_CHANNELS       (DMA_IRQ_CHAN_NR * 0x10 / 4)
+
 /*
  * sun8i specific registers
  */
@@ -65,7 +68,8 @@
 #define DMA_CHAN_LLI_ADDR      0x08
 
 #define DMA_CHAN_CUR_CFG       0x0c
-#define DMA_CHAN_CFG_SRC_DRQ(x)                ((x) & 0x1f)
+#define DMA_CHAN_MAX_DRQ               0x1f
+#define DMA_CHAN_CFG_SRC_DRQ(x)                ((x) & DMA_CHAN_MAX_DRQ)
 #define DMA_CHAN_CFG_SRC_IO_MODE       BIT(5)
 #define DMA_CHAN_CFG_SRC_LINEAR_MODE   (0 << 5)
 #define DMA_CHAN_CFG_SRC_BURST_A31(x)  (((x) & 0x3) << 7)
@@ -1174,6 +1178,7 @@ MODULE_DEVICE_TABLE(of, sun6i_dma_match);
 
 static int sun6i_dma_probe(struct platform_device *pdev)
 {
+       struct device_node *np = pdev->dev.of_node;
        struct sun6i_dma_dev *sdc;
        struct resource *res;
        int ret, i;
@@ -1248,6 +1253,26 @@ static int sun6i_dma_probe(struct platform_device *pdev)
        sdc->num_vchans = sdc->cfg->nr_max_vchans;
        sdc->max_request = sdc->cfg->nr_max_requests;
 
+       ret = of_property_read_u32(np, "dma-channels", &sdc->num_pchans);
+       if (ret && !sdc->num_pchans) {
+               dev_err(&pdev->dev, "Can't get dma-channels.\n");
+               return ret;
+       }
+
+       ret = of_property_read_u32(np, "dma-requests", &sdc->max_request);
+       if (ret && !sdc->max_request) {
+               dev_info(&pdev->dev, "Missing dma-requests, using %u.\n",
+                        DMA_CHAN_MAX_DRQ);
+               sdc->max_request = DMA_CHAN_MAX_DRQ;
+       }
+
+       /*
+        * If the number of vchans is not specified, derive it from the
+        * highest port number, at most one channel per port and direction.
+        */
+       if (!sdc->num_vchans)
+               sdc->num_vchans = 2 * (sdc->max_request + 1);
+
        sdc->pchans = devm_kcalloc(&pdev->dev, sdc->num_pchans,
                                   sizeof(struct sun6i_pchan), GFP_KERNEL);
        if (!sdc->pchans)