From d635711daa98be86d4c7fd01499c34f566b54ccb Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Fri, 10 Jun 2016 05:30:17 -0300 Subject: Linux-libre 4.6.2-gnu --- .../devicetree/bindings/regmap/regmap.txt | 56 ++++++++-------------- 1 file changed, 19 insertions(+), 37 deletions(-) (limited to 'Documentation/devicetree/bindings/regmap') diff --git a/Documentation/devicetree/bindings/regmap/regmap.txt b/Documentation/devicetree/bindings/regmap/regmap.txt index b494f8b8e..0127be360 100644 --- a/Documentation/devicetree/bindings/regmap/regmap.txt +++ b/Documentation/devicetree/bindings/regmap/regmap.txt @@ -1,47 +1,29 @@ -Device-Tree binding for regmap +Devicetree binding for regmap -The endianness mode of CPU & Device scenarios: -Index Device Endianness properties ---------------------------------------------------- -1 BE 'big-endian' -2 LE 'little-endian' +Optional properties: -For one device driver, which will run in different scenarios above -on different SoCs using the devicetree, we need one way to simplify -this. + little-endian, + big-endian, + native-endian: See common-properties.txt for a definition -Required properties: -- {big,little}-endian: these are boolean properties, if absent - meaning that the CPU and the Device are in the same endianness mode, - these properties are for register values and all the buffers only. +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. -Examples: -Scenario 1 : CPU in LE mode & device in LE mode. -dev: dev@40031000 { - compatible = "name"; - reg = <0x40031000 0x1000>; - ... -}; +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. -Scenario 2 : CPU in LE mode & device in BE mode. +Examples: +Scenario 1 : a register set in big-endian mode. dev: dev@40031000 { - compatible = "name"; + compatible = "syscon"; reg = <0x40031000 0x1000>; - ... big-endian; -}; - -Scenario 3 : CPU in BE mode & device in BE mode. -dev: dev@40031000 { - compatible = "name"; - reg = <0x40031000 0x1000>; - ... -}; - -Scenario 4 : CPU in BE mode & device in LE mode. -dev: dev@40031000 { - compatible = "name"; - reg = <0x40031000 0x1000>; ... - little-endian; }; -- cgit v1.2.3-54-g00ecf