From: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
When Linux is master of BAM, it can directly read registers to know number
of supported channels, however when its remotely controlled reading these
registers would trigger a crash if the BAM is not yet intialized/powered up
on the remote side.
This patch adds num-channels binding to specify number of supported
dma channels on remotely controlled BAM.
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
---
Documentation/devicetree/bindings/dma/qcom_bam_dma.txt | 2 ++
drivers/dma/qcom/bam_dma.c | 13 +++++++++++--
2 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt b/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
index 9cbf5d9df8fd..aa6822cbb230 100644
--- a/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
+++ b/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
@@ -15,6 +15,8 @@ Required properties:
the secure world.
- qcom,controlled-remotely : optional, indicates that the bam is controlled by
remote proccessor i.e. execution environment.
+- num-channels : optional, indicates supported number of DMA channels in a
+ remotely controlled bam.
Example:
diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
index 78e488e8f96d..523bd178047a 100644
--- a/drivers/dma/qcom/bam_dma.c
+++ b/drivers/dma/qcom/bam_dma.c
@@ -1083,8 +1083,10 @@ static int bam_init(struct bam_device *bdev)
if (bdev->ee >= val)
return -EINVAL;
- val = readl_relaxed(bam_addr(bdev, 0, BAM_NUM_PIPES));
- bdev->num_channels = val & BAM_NUM_PIPES_MASK;
+ if (!bdev->num_channels) {
+ val = readl_relaxed(bam_addr(bdev, 0, BAM_NUM_PIPES));
+ bdev->num_channels = val & BAM_NUM_PIPES_MASK;
+ }
if (bdev->controlled_remotely)
return 0;
@@ -1179,6 +1181,13 @@ static int bam_dma_probe(struct platform_device *pdev)
bdev->controlled_remotely = of_property_read_bool(pdev->dev.of_node,
"qcom,controlled-remotely");
+ if (bdev->controlled_remotely) {
+ ret = of_property_read_u32(pdev->dev.of_node, "num-channels",
+ &bdev->num_channels);
+ if (ret)
+ dev_err(bdev->dev, "num-channels unspecified in dt\n");
+ }
+
bdev->bamclk = devm_clk_get(bdev->dev, "bam_clk");
if (IS_ERR(bdev->bamclk)) {
bdev->bamclk = NULL;
--
2.15.1
--
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