powercap: occ: Add a generic powercap framework

This patch adds a generic powercap framework and exports OCC powercap
sensors using which system powercap can be set inband through OPAL-OCC
command-response interface.

Documentation for powercap enhanced by Stewart Smith.

Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/doc/device-tree/ibm,opal/power-mgt/powercap.rst b/doc/device-tree/ibm,opal/power-mgt/powercap.rst
new file mode 100644
index 00000000..e47caa46
--- /dev/null
+++ b/doc/device-tree/ibm,opal/power-mgt/powercap.rst
@@ -0,0 +1,48 @@
+power-mgt/powercap
+------------------
+
+The powercap sensors are populated in this node. Each child node in
+the "powercap" node represents a power-cappable component.
+
+For example : ::
+        system-powercap/
+
+The OPAL_GET_POWERCAP and OPAL_SET_POWERCAP calls take a handle for
+what powercap property to get/set which is defined in the child node.
+
+The compatible property for the linux driver which will be
+"ibm,opal-powercap"
+
+Each child node has below properties:
+
+`powercap-current`
+  Handle to indicate the current powercap
+
+`powercap-min`
+  Minimum possible powercap
+
+`powercap-max`
+  Maximum possible powercap
+
+Powercap handle uses the following encoding: ::
+
+        | Class |    Reserved   | Attribute |
+        |-------|---------------|-----------|
+
+Note: The format of the powercap handle is ``NOT`` ABI and may change in
+the future.
+
+.. code-block:: dts
+
+   power-mgt {
+     powercap {
+        compatible = "ibm,opal-powercap";
+
+        system-powercap {
+                name = "system-powercap"
+                powercap-current = <0x00000002>
+                powercap-min = <0x00000000>
+                powercap-max = <0x00000001>
+        };
+     };
+    }