Re: [PATCH v2 3/5] dmaengine: qcom: bam_dma: add controlled remotely dt property

gpramod
2016-04-11T07:53:21Z

On 2016-04-06 04:26, Stanimir Varbanov wrote:
> Some of the peripherals has bam which is controlled by remote
> processor, thus the bam dma driver must avoid register writes
> which initialise bam hw block. Those registers are protected
> from xPU block and any writes to them will lead to secure
> violation and system reboot.
>
> Adding the contolled_remotely flag in bam driver to avoid
> not permitted register writes in bam_init function.
>
> Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
> Reviewed-by: Andy Gross <andy.gross@linaro.org>
> ---
> Documentation/devicetree/bindings/dma/qcom_bam_dma.txt | 2 ++
> drivers/dma/qcom/bam_dma.c | 7 +++++++
> 2 files changed, 9 insertions(+)
>

Tested-by: Pramod Gurav <gpramod@codeaurora.org>

> diff --git a/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
> b/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
> index 1c9d48ea4914..9cbf5d9df8fd 100644
> --- a/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
> +++ b/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
> @@ -13,6 +13,8 @@ Required properties:
> - clock-names: must contain "bam_clk" entry
> - qcom,ee : indicates the active Execution Environment identifier
> (0-7) used in
> the secure world.
> +- qcom,controlled-remotely : optional, indicates that the bam is
> controlled by
> + remote proccessor i.e. execution environment.
>
> Example:
>
> diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
> index 789d5f836bf7..d0f878a78fae 100644
> --- a/drivers/dma/qcom/bam_dma.c
> +++ b/drivers/dma/qcom/bam_dma.c
> @@ -387,6 +387,7 @@ struct bam_device {
>
> /* execution environment ID, from DT */
> u32 ee;
> + bool controlled_remotely;
>
> const struct reg_offset_data *layout;
>
> @@ -1042,6 +1043,9 @@ static int bam_init(struct bam_device *bdev)
> val = readl_relaxed(bam_addr(bdev, 0, BAM_NUM_PIPES));
> bdev->num_channels = val & BAM_NUM_PIPES_MASK;
>
> + if (bdev->controlled_remotely)
> + return 0;
> +
> /* s/w reset bam */
> /* after reset all pipes are disabled and idle */
> val = readl_relaxed(bam_addr(bdev, 0, BAM_CTRL));
> @@ -1129,6 +1133,9 @@ static int bam_dma_probe(struct platform_device
> *pdev)
> return ret;
> }
>
> + bdev->controlled_remotely = of_property_read_bool(pdev->dev.of_node,
> + "qcom,controlled-remotely");
> +
> bdev->bamclk = devm_clk_get(bdev->dev, "bam_clk");
> if (IS_ERR(bdev->bamclk))
> return PTR_ERR(bdev->bamclk);