Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[linux-2.6-block.git] / Documentation / devicetree / bindings / regmap / regmap.txt

diff --git a/Documentation/devicetree/bindings/regmap/regmap.txt b/Documentation/devicetree/bindings/regmap/regmap.txt
index e98a9652ccc8c4d3a2263fe5a67b9064b27d1f04..0127be360fe852d70a853026c03de1fcc8c8a7a0 100644 (file)
--- a/Documentation/devicetree/bindings/regmap/regmap.txt
+++ b/Documentation/devicetree/bindings/regmap/regmap.txt
@@ -1,50 +1,29 @@
-Device-Tree binding for regmap
-
-The endianness mode of CPU & Device scenarios:
-Index     Device     Endianness properties
----------------------------------------------------
-1         BE         'big-endian'
-2         LE         'little-endian'
-3        Native     'native-endian'
-
-For one device driver, which will run in different scenarios above
-on different SoCs using the devicetree, we need one way to simplify
-this.
+Devicetree binding for regmap
 
 Optional properties:
-- {big,little,native}-endian: these are boolean properties, if absent
-  then the implementation will choose a default based on the device
-  being controlled.  These properties are for register values and all
-  the buffers only.  Native endian means that the CPU and device have
-  the same endianness.
 
-Examples:
-Scenario 1 : CPU in LE mode & device in LE mode.
-dev: dev@40031000 {
-             compatible = "name";
-             reg = <0x40031000 0x1000>;
-             ...
-};
+   little-endian,
+   big-endian,
+   native-endian:      See common-properties.txt for a definition
 
-Scenario 2 : CPU in LE mode & device in BE mode.
-dev: dev@40031000 {
-             compatible = "name";
-             reg = <0x40031000 0x1000>;
-             ...
-             big-endian;
-};
+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.
 
-Scenario 3 : CPU in BE mode & device in BE 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 4 : CPU in BE mode & device in LE mode.
+Examples:
+Scenario 1 : a register set in big-endian mode.
 dev: dev@40031000 {
-             compatible = "name";
+             compatible = "syscon";
              reg = <0x40031000 0x1000>;
+             big-endian;
              ...
-             little-endian;
 };