linux/Documentation/devicetree/bindings/regmap/regmap.txt
Arnd Bergmann 2596e07a3e regmap: fix documentation to match code
The regmap binding talks about one thing, which is register
endianess, and it gets almost every aspect of it wrong.

This replaces the current text of the file with a version
that makes more sense and that matches what we implement
now.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: a06c488da0 ("regmap: Add explict native endian flag to DT bindings")
Fixes: 275876e208 ("regmap: Add the DT binding documentation for endianness")
Signed-off-by: Mark Brown <broonie@kernel.org>
2016-03-17 18:42:25 +00:00

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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 endianess
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;
...
};