Hi Patrick,
I held off on reviewing this until we'd hashed out what we needed in the driver.
I have some comments below.
On Sat, 30 Mar 2019, at 01:40, Patrick Venture wrote:
> Document the ast2400, ast2500 PCI-to-AHB bridge control driver bindings.
>
> Signed-off-by: Patrick Venture <venture@xxxxxxxxxx>
> Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
> ---
> Changes for v8:
> - None
> Changes for v7:
> - Moved node under the syscon node it requires
> Changes for v6:
> - None
> Changes for v5:
> - None
> Changes for v4:
> - None
> Changes for v3:
> - None
> Changes for v2:
> - Added comment about syscon required parameter.
> ---
> .../bindings/misc/aspeed-p2a-ctrl.txt | 48 +++++++++++++++++++
> 1 file changed, 48 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
>
> diff --git a/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
> b/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
> new file mode 100644
> index 0000000000000..088cc4e3dc54b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
> @@ -0,0 +1,48 @@
> +======================================================================
> +Device tree bindings for Aspeed AST2400/AST2500 PCI-to-AHB Bridge
> Control Driver
> +======================================================================
> +
> +The bridge is available on platforms with the VGA enabled on the
> Aspeed device.
> +In this case, the host has access to a 64KiB window into all of the
> BMC's
> +memory. The BMC can disable this bridge. If the bridge is enabled,
> the host
> +has read access to all the regions of memory, however the host only
> has read
> +and write access depending on a register controlled by the BMC.
> +
> +Required properties:
> +===================
> +
> + - compatible: must be one of:
> + - "aspeed,ast2400-p2a-ctrl"
> + - "aspeed,ast2500-p2a-ctrl"
> +
> + - syscon: handle to syscon device node controlling PCI.
The p2a-ctrl node is meant to be a child of the syscon. I noted this in my review
of the associated driver - you need to remove the description of the syscon
property.
> +
> +Optional properties:
> +===================
> +
> +- memory-region: A phandle to a reserved_memory region to be used for
> the PCI
> + to AHB mapping
> +
> +The p2a-control node should be the child of a syscon node with the
> required
> +property:
> +
> +- compatible : Should be one of the following:
> + "aspeed,ast2400-scu", "syscon", "simple-mfd"
> + "aspeed,g4-scu", "syscon", "simple-mfd"
> + "aspeed,ast2500-scu", "syscon", "simple-mfd"
> + "aspeed,g5-scu", "syscon", "simple-mfd"
The note above should go where you've described the syscon property above.
Cheers,
Andrew
> +
> +Example:
> +
> +g4 Example
> +----------
> +
> +syscon: scu@1e6e2000 {
> + compatible = "aspeed,ast2400-scu", "syscon", "simple-mfd";
> + reg = <0x1e6e2000 0x1a8>;
> +
> + p2a: p2a-control {
> + compatible = "aspeed,ast2400-p2a-ctrl";
> + memory-region = <&reserved_memory>;
> + };
> +};
> --
> 2.21.0.392.gf8f6787159e-goog
>
>
