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..25307aa --- /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@10000000 { + ... + }; +}; -- 2.7.4
