clk: samsung: Add clock driver for S5PV210 and compatible SoCs

This patch adds new, Common Clock Framework-based clock driver for Samsung
S5PV210 and compatible SoCs. The driver is just added, without enabling it yet.

Signed-off-by: Mateusz Krawczuk <m.krawczuk@partner.samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
[t.figa: Added support for other SoC variants and clock output. Fixed
remaining minor issues.]
Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

Documentation/devicetree/bindings/clock/samsung,s5pv210-clock.txt

@@ -0,0 +1,78 @@
+* Samsung S5P6442/S5PC110/S5PV210 Clock Controller
+
+Samsung S5P6442, S5PC110 and S5PV210 SoCs contain integrated clock
+controller, which generates and supplies clock to various controllers
+within the SoC.
+
+Required Properties:
+
+- compatible: should be one of following:
+	- "samsung,s5pv210-clock" : for clock controller of Samsung
+	  S5PC110/S5PV210 SoCs,
+	- "samsung,s5p6442-clock" : for clock controller of Samsung
+	  S5P6442 SoC.
+
+- reg: physical base address of the controller and length of memory mapped
+  region.
+
+- #clock-cells: should be 1.
+
+All available clocks are defined as preprocessor macros in
+dt-bindings/clock/s5pv210.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:
+ - "xxti": external crystal oscillator connected to XXTI and XXTO pins of
+the SoC,
+ - "xusbxti": external crystal oscillator connected to XUSBXTI and XUSBXTO
+pins of the SoC,
+
+A subset of above clocks available on given board shall be specified in
+board device tree, including the system base clock, as selected by XOM[0]
+pin of the SoC. Refer to generic fixed rate clock bindings
+documentation[1] for more information how to specify these clocks.
+
+[1] Documentation/devicetree/bindings/clock/fixed-clock.txt
+
+Example: Clock controller node:
+
+	clock: clock-controller@7e00f000 {
+		compatible = "samsung,s5pv210-clock";
+		reg = <0x7e00f000 0x1000>;
+		#clock-cells = <1>;
+	};
+
+Example: Required external clocks:
+
+	xxti: clock-xxti {
+		compatible = "fixed-clock";
+		clock-output-names = "xxti";
+		clock-frequency = <24000000>;
+		#clock-cells = <0>;
+	};
+
+	xusbxti: clock-xusbxti {
+		compatible = "fixed-clock";
+		clock-output-names = "xusbxti";
+		clock-frequency = <24000000>;
+		#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@e2900000 {
+		compatible = "samsung,s5pv210-uart";
+		reg = <0xe2900000 0x400>;
+		interrupt-parent = <&vic1>;
+		interrupts = <10>;
+		clock-names = "uart", "clk_uart_baud0",
+				"clk_uart_baud1";
+		clocks = <&clocks UART0>, <&clocks UART0>,
+				<&clocks SCLK_UART0>;
+		status = "disabled";
+	};

drivers/clk/samsung/Makefile

@@ -16,3 +16,4 @@ obj-$(CONFIG_S3C2410_COMMON_DCLK)+= clk-s3c2410-dclk.o
 obj-$(CONFIG_S3C2412_COMMON_CLK)+= clk-s3c2412.o
 obj-$(CONFIG_S3C2443_COMMON_CLK)+= clk-s3c2443.o
 obj-$(CONFIG_ARCH_S3C64XX)	+= clk-s3c64xx.o
+obj-$(CONFIG_ARCH_S5PV210)	+= clk-s5pv210.o