psr: occ: Add support to change power-shifting-ratio

Add support to set the CPU-GPU power shifting ratio which is used by
the OCC power capping algorithm. PSR value of 100 takes all power away
from CPU first and a PSR value of 0 caps GPU first.

Documentation 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, 53 insertions, 0 deletions

diff --git a/doc/device-tree/ibm,opal/power-mgt/psr.rst b/doc/device-tree/ibm,opal/power-mgt/psr.rst
new file mode 100644
index 00000000..edae8da3
--- /dev/null
+++ b/doc/device-tree/ibm,opal/power-mgt/psr.rst
@@ -0,0 +1,53 @@
+power-mgt/psr
+------------------
+
+Some systems allow modification of how power consumption throttling
+is balanced between entities in a system. A typical one may be how the power
+management complex should balance throttling CPU versus the GPU. An OPAL
+call can be used to set these ratios, which are described in the device
+tree.
+
+In the future, there may be more available settings than just CPU
+versus GPU.
+
+Each child node in the "psr" node represents a configurable psr
+sensor.
+
+For example : ::
+        cpu-to-gpu@1
+
+The compatible property is set to "ibm,opal-power-shift-ratio".
+
+Each child node has below properties:
+
+`handle`
+  Handle to indicate the type of psr
+
+`label`
+  Name of the psr sensor
+
+The format of the handle is internal, and ``not`` ABI, although
+currently it uses the following encoding ::
+
+	| Class |Reserved|  RID	| Type |
+	|-------|--------|------|------|
+
+.. code-block:: dts
+
+   power-mgt {
+     psr {
+        compatible = "ibm,opal-power-shift-ratio"
+
+        cpu-to-gpu@0 {
+                name = "cpu-to-gpu"
+                handle = <0x00000000>
+                label = "cpu_to_gpu_0"
+        };
+
+        cpu-to-gpu@1 {
+                name = "cpu-to-gpu"
+                handle = <0x00000100>
+                label = "cpu_to_gpu_1"
+        };
+     };
+    };