nds32: Add document for NDS32 PMU.

The document for how to add NDS32 PMU
in devicetree.

Signed-off-by: Nickhu <nickhu@andestech.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Greentime Hu <greentime@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>

diff --git a/Documentation/devicetree/bindings/perf/nds32v3-pmu.txt b/Documentation/devicetree/bindings/perf/nds32v3-pmu.txt
new file mode 100644 (file)
index 0000000..1bd1578
--- /dev/null
+++ b/Documentation/devicetree/bindings/perf/nds32v3-pmu.txt
@@ -0,0 +1,17 @@
+* NDS32 Performance Monitor Units
+
+NDS32 core have a PMU for counting cpu and cache events like cache misses.
+The NDS32 PMU representation in the device tree should be done as under:
+
+Required properties:
+
+- compatible :
+       "andestech,nds32v3-pmu"
+
+- interrupts : The interrupt number for NDS32 PMU is 13.
+
+Example:
+pmu{
+       compatible = "andestech,nds32v3-pmu";
+       interrupts = <13>;
+}