ARC: clk: introduce HSDK CGU clock driver

Synopsys HSDK clock controller generates and supplies clocks to various
controllers and peripherals within the SoC.

Each clock has assigned identifier and client device tree nodes can use
this identifier to specify the clock which they consume. All available
clocks are defined as preprocessor macros in the
dt-bindings/clock/snps,hsdk-cgu.h header and can be used in device
tree sources.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/doc/device-tree-bindings/clock/snps,hsdk-cgu.txt b/doc/device-tree-bindings/clock/snps,hsdk-cgu.txt
new file mode 100644
index 00000000000..82fe1dd83ca
--- /dev/null
+++ b/doc/device-tree-bindings/clock/snps,hsdk-cgu.txt
@@ -0,0 +1,35 @@
+* Synopsys HSDK clock generation unit
+
+The Synopsys HSDK clock controller generates and supplies clock to various
+controllers and peripherals within the SoC.
+
+Required Properties:
+
+- compatible: should be "snps,hsdk-cgu-clock"
+- reg: the pair of physical base address and length of clock generation unit
+  memory mapped region and creg arc core divider memory mapped region.
+- #clock-cells: should be 1.
+
+Each clock is assigned an identifier and client nodes can use this identifier
+to specify the clock which they consume. All available clocks are defined as
+preprocessor macros in the dt-bindings/clock/snps,hsdk-cgu.h headers and can be
+used in device tree sources.
+
+Example: Clock controller node:
+
+	cgu_clk: cgu-clk@f0000000 {
+		compatible = "snps,hsdk-cgu-clock";
+		reg = <0xf0000000 0x1000>, <0xf00014B8 0x4>;
+		#clock-cells = <1>;
+	};
+
+Example: UART controller node that consumes the clock generated by the clock
+controller:
+
+	uart0: serial0@f0005000 {
+		compatible = "snps,dw-apb-uart";
+		reg = <0xf0005000 0x1000>;
+		reg-shift = <2>;
+		reg-io-width = <4>;
+		clocks = <&cgu_clk CLK_SYS_UART_REF>;
+	};