PM / devfreq: event: Add new Exynos NoC probe driver

This patch adds NoC (Network on Chip) Probe driver which provides
the primitive values to get the performance data. The packets that the Network
on Chip (NoC) probes detects are transported over the network infrastructure.
Exynos542x bus has multiple NoC probes to provide bandwidth information about
behavior of the SoC that you can use while analyzing system performance.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Tested-by: Markus Reichl <m.reichl@fivetechno.de>
Tested-by: Anand Moon <linux.amoon@gmail.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>

Documentation/devicetree/bindings/devfreq/event/exynos-nocp.txt

@@ -0,0 +1,26 @@
+
+* Samsung Exynos NoC (Network on Chip) Probe device
+
+The Samsung Exynos542x SoC has NoC (Network on Chip) Probe for NoC bus.
+NoC provides the primitive values to get the performance data. The packets
+that the Network on Chip (NoC) probes detects are transported over
+the network infrastructure to observer units. You can configure probes to
+capture packets with header or data on the data request response network,
+or as traffic debug or statistic collectors. Exynos542x bus has multiple
+NoC probes to provide bandwidth information about behavior of the SoC
+that you can use while analyzing system performance.
+
+Required properties:
+- compatible: Should be "samsung,exynos5420-nocp"
+- reg: physical base address of each NoC Probe and length of memory mapped region.
+
+Optional properties:
+- clock-names : the name of clock used by the NoC Probe, "nocp"
+- clocks : phandles for clock specified in "clock-names" property
+
+Example : NoC Probe nodes in Device Tree are listed below.
+
+	nocp_mem0_0: nocp@10CA1000 {
+		compatible = "samsung,exynos5420-nocp";
+		reg = <0x10CA1000 0x200>;
+	};