[PATCH v4 1/2] Documentation: dt: Add Xilinx zynqmp dma device tree binding documentation

[Rob Herring]

On Wed, Aug 5, 2015 at 10:19 PM, Punnaiah Choudary Kalluri
<punnaiah.choudary.kalluri at xilinx.com> wrote:
> Device-tree binding documentation for Xilinx zynqmp dma engine used in
> Zynq UltraScale+ MPSoC.
>
> Signed-off-by: Punnaiah Choudary Kalluri <punnaia at xilinx.com>
> ---
> Changes in v4:
> - None
> Changes in v3:
> - None
> Changes in v2:
> - None
> ---
>  .../devicetree/bindings/dma/xilinx/zynqmp_dma.txt  |   61 ++++++++++++++++++++
>  1 files changed, 61 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/dma/xilinx/zynqmp_dma.txt
>
> diff --git a/Documentation/devicetree/bindings/dma/xilinx/zynqmp_dma.txt b/Documentation/devicetree/bindings/dma/xilinx/zynqmp_dma.txt
> new file mode 100644
> index 0000000..e4f92b9
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/xilinx/zynqmp_dma.txt
> @@ -0,0 +1,61 @@
> +Xilinx ZynqMP DMA engine, it does support memory to memory transfers,
> +memory to device and device to memory transfers. It also has flow
> +control and rate control support for slave/peripheral dma access.
> +
> +Required properties:
> +- compatible: Should be "xlnx,zynqmp-dma-1.0"
> +- #dma-cells: Should be <1>, a single cell holding a line request number
> +- reg: Memory map for module access
> +- interrupt-parent: Interrupt controller the interrupt is routed through
> +- interrupts: Should contain DMA channel interrupt
> +- xlnx,bus-width: AXI buswidth in bits. Should contain 128 or 64
> +
> +Optional properties:
> +- xlnx,include-sg: Indicates the controller to operate in simple or scatter
> +                  gather dma mode
> +- xlnx,ratectrl: Scheduling interval in terms of clock cycles for
> +                source AXI transaction
> +- xlnx,overfetch: Tells whether the channel is allowed to over fetch the data
> +- xlnx,src-issue: Number of AXI outstanding transactions on source side
> +- xlnx,desc-axi-cohrnt: Tells whether the AXI transactions generated for the
> +                       descriptor read are marked Non-coherent
> +- xlnx,src-axi-cohrnt: Tells whether the AXI transactions generated for the
> +                       source descriptor payload are marked Non-coherent
> +- xlnx,dst-axi-cohrnt: Tells whether the AXI transactions generated for the
> +                       dst descriptor payload are marked Non-coherent

Do you really need 3? dma-coherent property doesn't work for you?

Not that it should dictate the binding, but the kernel doesn't support
a device needing both coherent and non-coherent DMA ops.

> +- xlnx,desc-axi-qos: AXI QOS bits to be used for descriptor fetch
> +- xlnx,src-axi-qos: AXI QOS bits to be used for data read
> +- xlnx,dst-axi-qos: AXI QOS bits to be used for data write
> +- xlnx,desc-axi-cache: AXI cache bits to be used for descriptor fetch.
> +- xlnx,desc-axi-cache: AXI cache bits to be used for data read
> +- xlnx,desc-axi-cache: AXI cache bits to be used for data write

These signals are generally part of the coherent or not setting. This
allows for potentially invalid combinations.

Plus you have a copy/paste error.

> +- xlnx,src-burst-len: AXI length for data read. Support only power of 2 values
> +                     i.e 1,2,4,8 and 16
> +- xlnx,dst-burst-len: AXI length for data write. Support only power of 2 values
> +                     i.e 1,2,4,8 and 16
> +
> +Example:
> +++++++++
> +fpd_dma_chan1: dma at FD500000 {
> +       compatible = "xlnx,zynqmp-dma-1.0";
> +       reg = <0x0 0xFD500000 0x1000>;
> +       #dma_cells = <1>;
> +       interrupt-parent = <&gic>;
> +       interrupts = <0 117 4>;
> +       xlnx,bus-width = <128>;
> +       xlnx,include-sg;
> +       xlnx,overfetch;
> +       xlnx,ratectrl = <0>;
> +       xlnx,src-issue = <16>;
> +       xlnx,desc-axi-cohrnt;
> +       xlnx,src-axi-cohrnt;
> +       xlnx,dst-axi-cohrnt;
> +       xlnx,desc-axi-qos = <0>;
> +       xlnx,desc-axi-cache = <0>;
> +       xlnx,src-axi-qos = <0>;
> +       xlnx,src-axi-cache = <2>;
> +       xlnx,dst-axi-qos = <0>;
> +       xlnx,dst-axi-cache = <2>;
> +       xlnx,src-burst-len = <4>;
> +       xlnx,dst-burst-len = <4>;
> +};
> --
> 1.7.4
>
>
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