On Tue, Oct 27, 2015 at 05:09:11PM -0500, atull@xxxxxxxxxxxxxxxxxxxxx wrote:
> From: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>
>
> New bindings document for simple fpga bus.
>
> Signed-off-by: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>
> ---
> v9: initial version added to this patchset
> v10: s/fpga/FPGA/g
> replace DT overlay example with slightly more complicated example
> move to staging/simple-fpga-bus
> v11: No change in this patch for v11 of the patch set
> v12: Moved out of staging.
> Changed to use FPGA bridges framework instead of resets
> for bridges.
> ---
> .../devicetree/bindings/fpga/simple-fpga-bus.txt | 81 ++++++++++++++++++++
> 1 file changed, 81 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/fpga/simple-fpga-bus.txt
>
> diff --git a/Documentation/devicetree/bindings/fpga/simple-fpga-bus.txt b/Documentation/devicetree/bindings/fpga/simple-fpga-bus.txt
> new file mode 100644
> index 0000000..2e742f7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/fpga/simple-fpga-bus.txt
> @@ -0,0 +1,81 @@
> +Simple FPGA Bus
> +===============
> +
> +A Simple FPGA Bus is a bus that handles configuring an FPGA and its bridges
> +before populating the devices below its node. All this happens when a device
> +tree overlay is added to the live tree. This document describes that device
> +tree overlay.
> +
> +Required properties:
> +- compatible : should contain "simple-fpga-bus"
> +- #address-cells, #size-cells, ranges: must be present to handle address space
> + mapping for children.
> +
> +Optional properties:
> +- fpga-mgr : should contain a phandle to a FPGA manager.
> +- fpga-firmware : should contain the name of a FPGA image file located on the
> + firmware search path.
> +- partial-reconfig : boolean property should be defined if partial
> + reconfiguration of the FPGA is to be done, otherwise full reconfiguration
> + is done.
> +- fpga-bridges : should contain a list of bridges that the bus will disable
> + before programming the FPGA and then enable after the FPGA has been
> +
> +Example:
> +
> +/dts-v1/;
> +/plugin/;
> +/ {
> + fragment@0 {
> + target-path="/soc";
> + __overlay__ {
> + #address-cells = <1>;
> + #size-cells = <1>;
> +
> + bridge@0xff200000 {
> + compatible = "simple-fpga-bus";
> + reg = <0xc0000000 0x20000000>,
> + <0xff200000 0x00200000>;
> + reg-names = "axi_h2f", "axi_h2f_lw";
> +
> + #address-cells = <0x2>;
> + #size-cells = <0x1>;
> +
> + ranges = <0x00000000 0x00000000 0xc0000000 0x00010000>,
> + <0x00000001 0x00020000 0xff220000 0x00000008>,
> + <0x00000001 0x00010040 0xff210040 0x00000020>;
> +
> + clocks = <0x2 0x2>;
> + clock-names = "h2f_lw_axi_clock", "f2h_sdram0_clock";
> +
> + fpga-mgr = <&hps_0_fpgamgr>;
> + fpga-firmware = "soc_system.rbf";
> +
> + fpga-bridges = <&hps_fpgabridge0>, <&hps_fpgabridge1>, <&hps_fpgabridge2>;
At least for Socfpga the HPS2FPGA and FPGA2HPS bridges can be configured to have
a bus width of 32, 64, 128 depending on the bitstream. How does this fit into here?
For DMA over this bus this is an interesting property to know, isn't it?
I guess something like "<&hps_fpgabridge0 64>" could be a possible solution, but
what is with the GPV registers of the bridges? Do they depend on the bitstream
loaded? Then this would get really messy I guess as it not a generic property.
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