devicetree: bindings: Add optional dynamic-power-coefficient property

The dynamic power consumption of a device is proportional to the
square of voltage (V) and the clock frequency (f). It can be expressed as

Pdyn = dynamic-power-coefficient * V^2 * f.

The coefficient represents the running time dynamic power consumption in
units of mw/MHz/uVolt^2 and can be used in the above formula to
calculate the dynamic power in mW.

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/Documentation/devicetree/bindings/arm/cpus.txt b/Documentation/devicetree/bindings/arm/cpus.txt
index 3a07a87..6aca64f 100644 (file)
--- a/Documentation/devicetree/bindings/arm/cpus.txt
+++ b/Documentation/devicetree/bindings/arm/cpus.txt
@@ -242,6 +242,23 @@ nodes to be present and contain the properties described below.
                Definition: Specifies the syscon node controlling the cpu core
                            power domains.
 
+       - dynamic-power-coefficient
+               Usage: optional
+               Value type: <prop-encoded-array>
+               Definition: A u32 value that represents the running time dynamic
+                           power coefficient in units of mW/MHz/uVolt^2. The
+                           coefficient can either be calculated from power
+                           measurements or derived by analysis.
+
+                           The dynamic power consumption of the CPU  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 uV, frequency is in MHz.
+
 Example 1 (dual-cluster big.LITTLE system 32-bit):
 
        cpus {