summaryrefslogtreecommitdiffstats
path: root/Documentation
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/devicetree/bindings/i2c/i2c-opal.txt37
1 files changed, 37 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/i2c/i2c-opal.txt b/Documentation/devicetree/bindings/i2c/i2c-opal.txt
new file mode 100644
index 000000000000..12bc61465ee5
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-opal.txt
@@ -0,0 +1,37 @@
+Device-tree bindings for I2C OPAL driver
+----------------------------------------
+
+Most of the device node and properties layout is specific to the firmware and
+used by the firmware itself for configuring the port. From the linux
+perspective, the properties of use are "ibm,port-name" and "ibm,opal-id".
+
+Required properties:
+
+- reg: Port-id within a given master
+- compatible: must be "ibm,opal-i2c"
+- ibm,opal-id: Refers to a specific bus and used to identify it when calling
+ the relevant OPAL functions.
+- bus-frequency: Operating frequency of the i2c bus (in HZ). Informational for
+ linux, used by the FW though.
+
+Optional properties:
+- ibm,port-name: Firmware provides this name that uniquely identifies the i2c
+ port.
+
+The node contains a number of other properties that are used by the FW itself
+and depend on the specific hardware implementation. The example below depicts
+a P8 on-chip bus.
+
+Example:
+
+i2c-bus@0 {
+ reg = <0x0>;
+ bus-frequency = <0x61a80>;
+ compatible = "ibm,power8-i2c-port", "ibm,opal-i2c";
+ ibm,opal-id = <0x1>;
+ ibm,port-name = "p8_00000000_e1p0";
+ #address-cells = <0x1>;
+ phandle = <0x10000006>;
+ #size-cells = <0x0>;
+ linux,phandle = <0x10000006>;
+};