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Date: Mon, 8 Sep 2014 11:36:00 +0100
From: Mark Rutland <mark.rutland@....com>
To: Stanimir Varbanov <svarbanov@...sol.com>
Cc: Ian Campbell <ijc+devicetree@...lion.org.uk>,
Pawel Moll <Pawel.Moll@....com>,
Rob Herring <robh+dt@...nel.org>,
Kumar Gala <galak@...eaurora.org>,
"grant.likely@...aro.org" <grant.likely@...aro.org>,
Andy Gross <agross@...eaurora.org>,
Vinod Koul <vinod.koul@...el.com>,
Dan Williams <dan.j.williams@...el.com>,
"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: Re: [PATCH] dmaengine: qcom_bam_dma: add one more optional clock
On Sun, Sep 07, 2014 at 06:55:47PM +0100, Stanimir Varbanov wrote:
> The BAM is tightly coupled with the peripheral to which it
> belongs. In that sprit to access the BAM configuration
> registers the driver needs to enable some peripheral
> clocks. Currently the DT node enables bamclk which seems
> is not enough for some peripherals (for example the crypto
> engine wants core and iface clocks). This change attempts
> to solve this issue by adding one more optional clock
> in bam_dma driver.
>
> Signed-off-by: Stanimir Varbanov <svarbanov@...sol.com>
> ---
> .../devicetree/bindings/dma/qcom_bam_dma.txt | 12 ++++--
> drivers/dma/qcom_bam_dma.c | 44 +++++++++++++++-------
> 2 files changed, 38 insertions(+), 18 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt b/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
> index d75a9d7..2376897 100644
> --- a/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
> +++ b/Documentation/devicetree/bindings/dma/qcom_bam_dma.txt
> @@ -6,8 +6,11 @@ Required properties:
> - interrupts: Should contain the one interrupt shared by all channels
> - #dma-cells: must be <1>, the cell in the dmas property of the client device
> represents the channel number
> -- clocks: required clock
> -- clock-names: must contain "bam_clk" entry
> +- clocks: list of required clock plus one optional clock. The optional clock
> + is needed for some peripherals and can be omitted.
> +- clock-names: must contain "core" clock name representing the required clock
> + plus the optional "iface" clock name depending on
> + peripheral needs.
Please don't change the names of input lines (at least without retaining
support for the old name). Does this change not break existing DTBs?
Which of these new names did "bam_clk" previously correspond to?
How many clock inputs does the BAM actually have? Are there more which
we don't yet describe?
You mention that the iface clock is actually fed into the peripheral the
BAM is attached to. Can you explain why this clock is necessary to use
the BAM?
If you want do describe multiple clocks and names are required, define
clocks in terms of clock-names so you don't need to state everything
twice, Put each clock on a new line, e.g.
- clocks: A list of phandle + clock-specifier pairs, one for each entry
in clock-names
- clock-names: should contain:
* "foo_clk" for the FOO clock
* "bar_clk" for the BAR input on baz_xxxx systems
Thanks,
Mark.
> - qcom,ee : indicates the active Execution Environment identifier (0-7) used in
> the secure world.
>
> @@ -17,8 +20,9 @@ Example:
> compatible = "qcom,bam-v1.4.0";
> reg = <0xf9984000 0x15000>;
> interrupts = <0 94 0>;
> - clocks = <&gcc GCC_BAM_DMA_AHB_CLK>;
> - clock-names = "bam_clk";
> + clocks = <&gcc GCC_BLSP1_UART2_APPS_CLK>,
> + <&gcc GCC_BLSP1_AHB_CLK>;
> + clock-names = "core", "iface";
> #dma-cells = <1>;
> qcom,ee = <0>;
> };
> diff --git a/drivers/dma/qcom_bam_dma.c b/drivers/dma/qcom_bam_dma.c
> index 7a4bbb0..d898ec3 100644
> --- a/drivers/dma/qcom_bam_dma.c
> +++ b/drivers/dma/qcom_bam_dma.c
> @@ -297,7 +297,7 @@ struct bam_device {
> /* execution environment ID, from DT */
> u32 ee;
>
> - struct clk *bamclk;
> + struct clk *iface, *core;
> int irq;
>
> /* dma start transaction tasklet */
> @@ -996,19 +996,32 @@ static int bam_dma_probe(struct platform_device *pdev)
> return ret;
> }
>
> - bdev->bamclk = devm_clk_get(bdev->dev, "bam_clk");
> - if (IS_ERR(bdev->bamclk))
> - return PTR_ERR(bdev->bamclk);
> + bdev->core = devm_clk_get(bdev->dev, "core");
> + if (IS_ERR(bdev->core))
> + return PTR_ERR(bdev->core);
>
> - ret = clk_prepare_enable(bdev->bamclk);
> + ret = clk_prepare_enable(bdev->core);
> if (ret) {
> - dev_err(bdev->dev, "failed to prepare/enable clock\n");
> + dev_err(bdev->dev, "failed to prepare/enable core clock\n");
> return ret;
> }
>
> + bdev->iface = devm_clk_get(bdev->dev, "iface");
> + if (IS_ERR(bdev->iface) && PTR_ERR(bdev->iface) == -EPROBE_DEFER) {
> + ret = -EPROBE_DEFER;
> + goto err_disable_core_clk;
> + } else if (!IS_ERR(bdev->iface)) {
> + ret = clk_prepare_enable(bdev->iface);
> + if (ret) {
> + dev_err(bdev->dev,
> + "failed to prepare/enable iface clock\n");
> + goto err_disable_core_clk;
> + }
> + }
> +
> ret = bam_init(bdev);
> if (ret)
> - goto err_disable_clk;
> + goto err_disable_clks;
>
> tasklet_init(&bdev->task, dma_tasklet, (unsigned long)bdev);
>
> @@ -1017,7 +1030,7 @@ static int bam_dma_probe(struct platform_device *pdev)
>
> if (!bdev->channels) {
> ret = -ENOMEM;
> - goto err_disable_clk;
> + goto err_disable_clks;
> }
>
> /* allocate and initialize channels */
> @@ -1029,7 +1042,7 @@ static int bam_dma_probe(struct platform_device *pdev)
> ret = devm_request_irq(bdev->dev, bdev->irq, bam_dma_irq,
> IRQF_TRIGGER_HIGH, "bam_dma", bdev);
> if (ret)
> - goto err_disable_clk;
> + goto err_disable_clks;
>
> /* set max dma segment size */
> bdev->common.dev = bdev->dev;
> @@ -1037,7 +1050,7 @@ static int bam_dma_probe(struct platform_device *pdev)
> ret = dma_set_max_seg_size(bdev->common.dev, BAM_MAX_DATA_SIZE);
> if (ret) {
> dev_err(bdev->dev, "cannot set maximum segment size\n");
> - goto err_disable_clk;
> + goto err_disable_clks;
> }
>
> platform_set_drvdata(pdev, bdev);
> @@ -1058,7 +1071,7 @@ static int bam_dma_probe(struct platform_device *pdev)
> ret = dma_async_device_register(&bdev->common);
> if (ret) {
> dev_err(bdev->dev, "failed to register dma async device\n");
> - goto err_disable_clk;
> + goto err_disable_clks;
> }
>
> ret = of_dma_controller_register(pdev->dev.of_node, bam_dma_xlate,
> @@ -1070,8 +1083,10 @@ static int bam_dma_probe(struct platform_device *pdev)
>
> err_unregister_dma:
> dma_async_device_unregister(&bdev->common);
> -err_disable_clk:
> - clk_disable_unprepare(bdev->bamclk);
> +err_disable_clks:
> + clk_disable_unprepare(bdev->iface);
> +err_disable_core_clk:
> + clk_disable_unprepare(bdev->core);
> return ret;
> }
>
> @@ -1099,7 +1114,8 @@ static int bam_dma_remove(struct platform_device *pdev)
>
> tasklet_kill(&bdev->task);
>
> - clk_disable_unprepare(bdev->bamclk);
> + clk_disable_unprepare(bdev->iface);
> + clk_disable_unprepare(bdev->core);
>
> return 0;
> }
> --
> 1.8.3.2
>
>
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