clk: si570: Add a driver for SI570 oscillators

Add a driver for SILabs 570, 571, 598, 599 programmable oscillators.
The devices generate low-jitter clock signals and are reprogrammable via
an I2C interface.
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>

Documentation/devicetree/bindings/clock/silabs,si570.txt

+Binding for Silicon Labs 570, 571, 598 and 599 programmable
+I2C clock generators.
+
+Reference
+This binding uses the common clock binding[1]. Details about the devices can be
+found in the data sheets[2][3].
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+[2] Si570/571 Data Sheet
+    http://www.silabs.com/Support%20Documents/TechnicalDocs/si570.pdf
+[3] Si598/599 Data Sheet
+    http://www.silabs.com/Support%20Documents/TechnicalDocs/si598-99.pdf
+
+Required properties:
+ - compatible: Shall be one of "silabs,si570", "silabs,si571",
+			       "silabs,si598", "silabs,si599"
+ - reg: I2C device address.
+ - #clock-cells: From common clock bindings: Shall be 0.
+ - factory-fout: Factory set default frequency. This frequency is part specific.
+		 The correct frequency for the part used has to be provided in
+		 order to generate the correct output frequencies. For more
+		 details, please refer to the data sheet.
+ - temperature-stability: Temperature stability of the device in PPM. Should be
+			  one of: 7, 20, 50 or 100.
+
+Optional properties:
+ - clock-output-names: From common clock bindings. Recommended to be "si570".
+ - clock-frequency: Output frequency to generate. This defines the output
+		    frequency set during boot. It can be reprogrammed during
+		    runtime through the common clock framework.
+
+Example:
+	si570: clock-generator@5d {
+		#clock-cells = <0>;
+		compatible = "silabs,si570";
+		temperature-stability = <50>;
+		reg = <0x5d>;
+		factory-fout = <156250000>;
+	};

drivers/clk/Kconfig

@@ -64,6 +64,16 @@ config COMMON_CLK_SI5351
 	  This driver supports Silicon Labs 5351A/B/C programmable clock
 	  generators.
 
+config COMMON_CLK_SI570
+	tristate "Clock driver for SiLabs 570 and compatible devices"
+	depends on I2C
+	depends on OF
+	select REGMAP_I2C
+	help
+	---help---
+	  This driver supports Silicon Labs 570/571/598/599 programmable
+	  clock generators.
+
 config COMMON_CLK_S2MPS11
 	tristate "Clock driver for S2MPS11 MFD"
 	depends on MFD_SEC_CORE

drivers/clk/Makefile

@@ -45,6 +45,7 @@ obj-$(CONFIG_COMMON_CLK_AXI_CLKGEN) += clk-axi-clkgen.o
 obj-$(CONFIG_COMMON_CLK_WM831X) += clk-wm831x.o
 obj-$(CONFIG_COMMON_CLK_MAX77686) += clk-max77686.o
 obj-$(CONFIG_COMMON_CLK_SI5351) += clk-si5351.o
+obj-$(CONFIG_COMMON_CLK_SI570) += clk-si570.o
 obj-$(CONFIG_COMMON_CLK_S2MPS11) += clk-s2mps11.o
 obj-$(CONFIG_CLK_TWL6040)	+= clk-twl6040.o
 obj-$(CONFIG_CLK_PPC_CORENET)	+= clk-ppc-corenet.o