dmaengine: qcom: bam_dma: get num-channels and num-ees from dt

BugLink: http://bugs.launchpad.net/bugs/1786352
[ Upstream commit 48d163b1aa6e7f650c0b7a4f9c61c387a6def868 ]

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 initialized or
powered up on the remote side.

This patch allows driver to read num-channels and num-ees from Device Tree
for remotely controlled BAM.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
index d076940e0c69ada23dc451367df9d71c88649dc7..4cc58904ee520d5b6597d3d3c794365a48646b20 100644 (file)
--- a/drivers/dma/qcom/bam_dma.c
+++ b/drivers/dma/qcom/bam_dma.c
@@ -393,6 +393,7 @@ struct bam_device {
        struct device_dma_parameters dma_parms;
        struct bam_chan *channels;
        u32 num_channels;
+       u32 num_ees;
 
        /* execution environment ID, from DT */
        u32 ee;
@@ -1128,15 +1129,19 @@ static int bam_init(struct bam_device *bdev)
        u32 val;
 
        /* read revision and configuration information */
-       val = readl_relaxed(bam_addr(bdev, 0, BAM_REVISION)) >> NUM_EES_SHIFT;
-       val &= NUM_EES_MASK;
+       if (!bdev->num_ees) {
+               val = readl_relaxed(bam_addr(bdev, 0, BAM_REVISION));
+               bdev->num_ees = (val >> NUM_EES_SHIFT) & NUM_EES_MASK;
+       }
 
        /* check that configured EE is within range */
-       if (bdev->ee >= val)
+       if (bdev->ee >= bdev->num_ees)
                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;
@@ -1232,6 +1237,18 @@ 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");
+
+               ret = of_property_read_u32(pdev->dev.of_node, "qcom,num-ees",
+                                          &bdev->num_ees);
+               if (ret)
+                       dev_err(bdev->dev, "num-ees unspecified in dt\n");
+       }
+
        bdev->bamclk = devm_clk_get(bdev->dev, "bam_clk");
        if (IS_ERR(bdev->bamclk))
                return PTR_ERR(bdev->bamclk);