dt-bindings: mali-midgard: Add dynamic-power-coefficient

Add a property dynamic-power-coefficient which allows to register Energy
Model for the Mali Midgard devices.

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Link: https://lore.kernel.org/r/20201209115143.15321-2-lukasz.luba@arm.com
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/gpu/arm,mali-midgard.yaml

@@ -90,6 +90,23 @@ properties:
 
   dma-coherent: true
 
+  dynamic-power-coefficient:
+    $ref: '/schemas/types.yaml#/definitions/uint32'
+    description:
+      A u32 value that represents the running time dynamic
+      power coefficient in units of uW/MHz/V^2. The
+      coefficient can either be calculated from power
+      measurements or derived by analysis.
+
+      The dynamic power consumption of the GPU is
+      proportional to the square of the Voltage (V) and
+      the clock frequency (f). The coefficient is used to
+      calculate the dynamic power as below -
+
+      Pdyn = dynamic-power-coefficient * V^2 * f
+
+      where voltage is in V, frequency is in MHz.
+
 required:
   - compatible
   - reg