dt-bindings: clock: renesas,r9a06g032-sysctrl: documentation

The Renesas R9A06G032 SYSCTRL node description.
Signed-off-by: Michel Pollet <michel.pollet@bp.renesas.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

Documentation/devicetree/bindings/clock/renesas,r9a06g032-sysctrl.txt

+* Renesas R9A06G032 SYSCTRL
+
+Required Properties:
+
+  - compatible: Must be:
+    - "renesas,r9a06g032-sysctrl"
+  - reg: Base address and length of the SYSCTRL IO block.
+  - #clock-cells: Must be 1
+  - clocks: References to the parent clocks:
+	- external 40mhz crystal.
+	- external (optional) 32.768khz
+	- external (optional) jtag input
+	- external (optional) RGMII_REFCLK
+  - clock-names: Must be:
+        clock-names = "mclk", "rtc", "jtag", "rgmii_ref_ext";
+
+Examples
+--------
+
+  - SYSCTRL node:
+
+	sysctrl: system-controller@4000c000 {
+		compatible = "renesas,r9a06g032-sysctrl";
+		reg = <0x4000c000 0x1000>;
+		#clock-cells = <1>;
+
+		clocks = <&ext_mclk>, <&ext_rtc_clk>,
+				<&ext_jtag_clk>, <&ext_rgmii_ref>;
+		clock-names = "mclk", "rtc", "jtag", "rgmii_ref_ext";
+	};
+
+  - Other nodes can use the clocks provided by SYSCTRL as in:
+
+	#include <dt-bindings/clock/r9a06g032-sysctrl.h>
+	uart0: serial@40060000 {
+		compatible = "snps,dw-apb-uart";
+		reg = <0x40060000 0x400>;
+		interrupts = <GIC_SPI 6 IRQ_TYPE_LEVEL_HIGH>;
+		reg-shift = <2>;
+		reg-io-width = <4>;
+		clocks = <&sysctrl R9A06G032_CLK_UART0>;
+		clock-names = "baudclk";
+	};