Re: [PATCHv6 2/2] dt/bindings: Add the DT binding documentation for endianness

From: Varka Bhadram
Date: Tue Jul 15 2014 - 01:34:51 EST


On 07/15/2014 09:53 AM, Xiubo Li wrote:
Device-Tree binding for device endianness
Index Device Endianness properties
---------------------------------------------------
1 BE 'big-endian'
2 LE 'little-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.

Signed-off-by: Xiubo Li <Li.Xiubo@xxxxxxxxxxxxx>
---
.../devicetree/bindings/regmap/regmap.txt | 47 ++++++++++++++++++++++
1 file changed, 47 insertions(+)
create mode 100644 Documentation/devicetree/bindings/regmap/regmap.txt

diff --git a/Documentation/devicetree/bindings/regmap/regmap.txt b/Documentation/devicetree/bindings/regmap/regmap.txt
new file mode 100644
index 0000000..b494f8b
--- /dev/null
+++ b/Documentation/devicetree/bindings/regmap/regmap.txt
@@ -0,0 +1,47 @@
+Device-Tree binding for regmap
+
+The endianness mode of CPU & Device scenarios:
+Index Device Endianness properties
+---------------------------------------------------
+1 BE 'big-endian'
+2 LE 'little-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.
+
+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.
+

It would be more readable if its like this:
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 propperties are for
values and all the buffers only.

+Examples:
+Scenario 1 : CPU in LE mode & device in LE mode.
+dev: dev@40031000 {
+ compatible = "name";
+ reg = <0x40031000 0x1000>;
+ ...
+};
+
+Scenario 2 : CPU in LE mode & device in BE mode.
+dev: dev@40031000 {
+ compatible = "name";
+ 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;
+};


--
Regards,
Varka Bhadram.

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