clk: samsung: Add clock driver for S3C64xx SoCs

This patch adds new, Common Clock Framework-based clock driver for Samsung
S3C64xx SoCs. The driver is just added, without actually letting the
platforms use it yet, since this requires more intermediate steps.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

Documentation/devicetree/bindings/clock/samsung,s3c64xx-clock.txt

@@ -0,0 +1,77 @@
+* Samsung S3C64xx Clock Controller
+
+The S3C64xx clock controller generates and supplies clock to various controllers
+within the SoC. The clock binding described here is applicable to all SoCs in
+the S3C64xx family.
+
+Required Properties:
+
+- compatible: should be one of the following.
+  - "samsung,s3c6400-clock" - controller compatible with S3C6400 SoC.
+  - "samsung,s3c6410-clock" - controller compatible with S3C6410 SoC.
+
+- reg: physical base address of the controller and length of 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. Some of the clocks are available only
+on a particular S3C64xx SoC and this is specified where applicable.
+
+All available clocks are defined as preprocessor macros in
+dt-bindings/clock/samsung,s3c64xx-clock.h header and can be used in device
+tree sources.
+
+External clocks:
+
+There are several clocks that are generated outside the SoC. It is expected
+that they are defined using standard clock bindings with following
+clock-output-names:
+ - "fin_pll" - PLL input clock (xtal/extclk) - required,
+ - "xusbxti" - USB xtal - required,
+ - "iiscdclk0" - I2S0 codec clock - optional,
+ - "iiscdclk1" - I2S1 codec clock - optional,
+ - "iiscdclk2" - I2S2 codec clock - optional,
+ - "pcmcdclk0" - PCM0 codec clock - optional,
+ - "pcmcdclk1" - PCM1 codec clock - optional, only S3C6410.
+
+Example: Clock controller node:
+
+	clock: clock-controller@7e00f000 {
+		compatible = "samsung,s3c6410-clock";
+		reg = <0x7e00f000 0x1000>;
+		#clock-cells = <1>;
+	};
+
+Example: Required external clocks:
+
+	fin_pll: clock-fin-pll {
+		compatible = "fixed-clock";
+		clock-output-names = "fin_pll";
+		clock-frequency = <12000000>;
+		#clock-cells = <0>;
+	};
+
+	xusbxti: clock-xusbxti {
+		compatible = "fixed-clock";
+		clock-output-names = "xusbxti";
+		clock-frequency = <48000000>;
+		#clock-cells = <0>;
+	};
+
+Example: UART controller node that consumes the clock generated by the clock
+  controller (refer to the standard clock bindings for information about
+  "clocks" and "clock-names" properties):
+
+		uart0: serial@7f005000 {
+			compatible = "samsung,s3c6400-uart";
+			reg = <0x7f005000 0x100>;
+			interrupt-parent = <&vic1>;
+			interrupts = <5>;
+			clock-names = "uart", "clk_uart_baud2",
+					"clk_uart_baud3";
+			clocks = <&clock PCLK_UART0>, <&clocks PCLK_UART0>,
+					<&clock SCLK_UART>;
+			status = "disabled";
+		};