linuxdebug/Documentation/devicetree/bindings/regmap/regmap.txt

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Devicetree binding for regmap
Optional properties:
little-endian,
big-endian,
native-endian: See common-properties.txt for a definition
Note:
Regmap defaults to little-endian register access on MMIO based
devices, this is by far the most common setting. On CPU
architectures that typically run big-endian operating systems
(e.g. PowerPC), registers can be defined as big-endian and must
be marked that way in the devicetree.
On SoCs that can be operated in both big-endian and little-endian
modes, with a single hardware switch controlling both the endianness
of the CPU and a byteswap for MMIO registers (e.g. many Broadcom MIPS
chips), "native-endian" is used to allow using the same device tree
blob in both cases.
Examples:
Scenario 1 : a register set in big-endian mode.
dev: dev@40031000 {
compatible = "syscon";
reg = <0x40031000 0x1000>;
big-endian;
...
};