Re: [PATCH v2 1/8] dt-bindings: stm32: add bindings for ML-AHB interconnect

[Rob Herring]

On Tue, Apr 16, 2019 at 04:58:12PM +0200, Fabien Dessenne wrote:
> Document the ML-AHB interconnect for stm32 SoCs.
> 
> Signed-off-by: Fabien Dessenne <fabien.dessenne@xxxxxx>
> ---
>  .../devicetree/bindings/arm/stm32/mlahb.txt        | 37 ++++++++++++++++++++++
>  1 file changed, 37 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/stm32/mlahb.txt
> 
> diff --git a/Documentation/devicetree/bindings/arm/stm32/mlahb.txt b/Documentation/devicetree/bindings/arm/stm32/mlahb.txt
> new file mode 100644
> index 0000000..a36458a
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/stm32/mlahb.txt
> @@ -0,0 +1,37 @@
> +ML-AHB interconnect bindings
> +
> +These bindings describe the STM32 SoCs ML-AHB interconnect bus which connects
> +a Cortex-M subsystem with dedicated memories.
> +The MCU SRAM and RETRAM memory parts can be accessed through different addresses
> +(see "RAM aliases" in [1]) using different buses (see [2]) : balancing the
> +Cortex-M firmware accesses among those ports allows to tune the system
> +performance.
> +
> +[1]: https://www.st.com/resource/en/reference_manual/dm00327659.pdf
> +[2]: https://wiki.st.com/stm32mpu/wiki/STM32MP15_RAM_mapping
> +
> +Required properties:
> +- compatible: should be "simple-bus"
> +- dma-ranges: describes memory addresses translation between the local CPU and
> +	   the remote Cortex-M processor. Each memory region, is declared with
> +	   3 parameters:
> +		 - param 1: device base address (Cortex-M processor address)
> +		 - param 2: physical base address (local CPU address)
> +		 - param 3: size of the memory region.
> +
> +The Cortex-M remote processor accessed via the mlahb interconnect is described
> +by a child node.
> +
> +Example:
> +mlahb {
> +	compatible = "simple-bus";
> +	#address-cells = <1>;
> +	#size-cells = <1>;
> +	dma-ranges = <0x00000000 0x38000000 0x10000>,
> +		     <0x10000000 0x10000000 0x60000>,
> +		     <0x30000000 0x30000000 0x60000>;
> +
> +	m4_rproc: m4@0 {

'0' is a cpu address given there's no 'ranges' now for translating cpu 
addresses. I think you want it to be 0x38000000 instead. 

> +		...
> +	};
> +};
> -- 
> 2.7.4
>