Merge tag 'afs-next-20171113' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowel...

[sfrench/cifs-2.6.git] / Documentation / devicetree / bindings / common-properties.txt

diff --git a/Documentation/devicetree/bindings/common-properties.txt b/Documentation/devicetree/bindings/common-properties.txt
index 697714f8d75cde0f759fad65f4da217b03598c1d..a3448bfa1c827971f6d0e9c33e31c7636a0ce1b9 100644 (file)
--- a/Documentation/devicetree/bindings/common-properties.txt
+++ b/Documentation/devicetree/bindings/common-properties.txt
@@ -1,4 +1,8 @@
 Common properties
+=================
+
+Endianness
+----------
 
 The Devicetree Specification does not define any properties related to hardware
 byteswapping, but endianness issues show up frequently in porting Linux to
@@ -58,3 +62,25 @@ dev: dev@40031000 {
              ...
              little-endian;
 };
+
+Daisy-chained devices
+---------------------
+
+Many serially-attached GPIO and IIO devices are daisy-chainable.  To the
+host controller, a daisy-chain appears as a single device, but the number
+of inputs and outputs it provides is the sum of inputs and outputs provided
+by all of its devices.  The driver needs to know how many devices the
+daisy-chain comprises to determine the amount of data exchanged, how many
+inputs and outputs to register and so on.
+
+Optional properties:
+ - #daisy-chained-devices: Number of devices in the daisy-chain (default is 1).
+
+Example:
+gpio@0 {
+             compatible = "name";
+             reg = <0>;
+             gpio-controller;
+             #gpio-cells = <2>;
+             #daisy-chained-devices = <3>;
+};