On Tuesday 25 February 2014, Heiko Stübner wrote:
> Some SoCs need parts of their sram for special purposes. So while being part
> of the peripheral, it should not be part of the genpool controlling the sram.
>
> Therefore add the option to define reserved regions as subnodes of the
> sram-node similar to defining reserved global memory regions.
[adding Sachin Kamat to Cc, he just had the same issue]
> Originally
> Suggested-by: Rob Herring <robherring2@xxxxxxxxx>
>
> Using subnodes for reserved regions
> Suggested-by: Grant Likely <grant.likely@xxxxxxxxxx>
>
> Signed-off-by: Heiko Stuebner <heiko@xxxxxxxxx>
> Tested-by: Ulrich Prinz <ulrich.prinz@xxxxxxxxxxxxxx>
> ---
> Documentation/devicetree/bindings/misc/sram.txt | 33 +++++++++++++++++++++++++
> 1 file changed, 33 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/misc/sram.txt b/Documentation/devicetree/bindings/misc/sram.txt
> index 4d0a00e..2d83758 100644
> --- a/Documentation/devicetree/bindings/misc/sram.txt
> +++ b/Documentation/devicetree/bindings/misc/sram.txt
> @@ -8,9 +8,42 @@ Required properties:
>
> - reg : SRAM iomem address range
>
> +Reserving sram areas:
> +---------------------
> +
> +Each child of the sram node specifies a region of reserved memory. Each
> +child node should use a 'reg' property to specify a specific range of
> +reserved memory.
> +
> +Following the generic-names recommended practice, node names should
> +reflect the purpose of the node. Unit address (@<address>) should be
> +appended to the name.
> +
> +Required properties in the sram node:
> +
> +- #address-cells, #size-cells : should use the same values as the root node
> +- ranges : standard definition, should be empty
I think we should rather define the 'ranges' property to translate from
addresses within the sram to bus addresses.
> +Required properties in the area nodes:
> +
> +- reg : iomem address range
> +
> +Optional properties in the area nodes:
> +
> +- compatible : standard definition
> +
Is this enough? Normally we should define a list of "compatible" strings
that people can add to, but not have an anything-allowed option.
> Example:
>
> sram: sram@5c000000 {
> compatible = "mmio-sram";
> reg = <0x5c000000 0x40000>; /* 256 KiB SRAM at address 0x5c000000 */
> +
> + #adress-cells = <1>;
> + #size-cells = <1>;
> + ranges;
> +
> + smp-sram@5c000100 {
> + compatible = "socvendor,smp-sram";
> + reg = <0x5c000100 0x50>;
> + };
> };
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