[PATCH 07/10] dmaengine: sun6i: Retrieve channel count/max request from devicetree

Stefan Brüns
2017-09-03T22:41:19Z

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>
---
drivers/dma/sun6i-dma.c | 35 ++++++++++++++++++++++++++++++++++-
1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
index c69dadb853d2..bd4c2e4a759b 100644
--- 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)
@@ -1173,6 +1177,35 @@ 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;
+ }
+
+ if (sdc->num_pchans > DMA_MAX_CHANNELS) {
+ dev_err(&pdev->dev, "Number of dma-channels out of range.\n");
+ return -EINVAL;
+ }
+
+ 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);
+ }
+
+ if (sdc->max_request > DMA_CHAN_MAX_DRQ) {
+ dev_err(&pdev->dev, "Value of dma-requests out of range.\n");
+ return -EINVAL;
+ }
+
+ /*
+ * 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)
--
2.14.1