[deliverable/linux.git] / Documentation / devicetree / bindings / regmap / regmap.txt

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;
	      ...
};
Commit	Line	Data
2596e07a	1	Devicetree binding for regmap
275876e2	2
a06c488d	3	Optional properties:
275876e2	4
2596e07a AB	5	little-endian,
	6	big-endian,
	7	native-endian: See common-properties.txt for a definition
275876e2	8
2596e07a AB	9	Note:
	10	Regmap defaults to little-endian register access on MMIO based
	11	devices, this is by far the most common setting. On CPU
	12	architectures that typically run big-endian operating systems
	13	(e.g. PowerPC), registers can be defined as big-endian and must
	14	be marked that way in the devicetree.
275876e2	15
2596e07a	16	On SoCs that can be operated in both big-endian and little-endian
7587eb18	17	modes, with a single hardware switch controlling both the endianness
2596e07a AB	18	of the CPU and a byteswap for MMIO registers (e.g. many Broadcom MIPS
	19	chips), "native-endian" is used to allow using the same device tree
	20	blob in both cases.
275876e2	21
2596e07a AB	22	Examples:
2596e07a AB	23	Scenario 1 : a register set in big-endian mode.
275876e2	24	dev: dev@40031000 {
2596e07a	25	compatible = "syscon";
275876e2	26	reg = <0x40031000 0x1000>;
2596e07a	27	big-endian;
275876e2	28	...
275876e2	29	};