Add TI CDCE925 I2C controlled clock synthesizer driver

This driver supports the TI CDCE925 programmable clock synthesizer.
The chip contains two PLLs with spread-spectrum clocking support and
five output dividers. The driver only supports the following setup,
and uses a fixed setting for the output muxes:
  Y1 is derived from the input clock
  Y2 and Y3 derive from PLL1
  Y4 and Y5 derive from PLL2
Given a target output frequency, the driver will set the PLL and
divider to best approximate the desired output.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Signed-off-by: Michael Turquette <mturquette@linaro.org>

1 files changed, 42 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/clock/ti,cdce925.txt b/Documentation/devicetree/bindings/clock/ti,cdce925.txt
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+++ b/Documentation/devicetree/bindings/clock/ti,cdce925.txt
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+Binding for TO CDCE925 programmable I2C clock synthesizers.
+
+Reference
+This binding uses the common clock binding[1].
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+[2] http://www.ti.com/product/cdce925
+
+The driver provides clock sources for each output Y1 through Y5.
+
+Required properties:
+ - compatible: Shall be "ti,cdce925"
+ - reg: I2C device address.
+ - clocks: Points to a fixed parent clock that provides the input frequency.
+ - #clock-cells: From common clock bindings: Shall be 1.
+
+Optional properties:
+ - xtal-load-pf: Crystal load-capacitor value to fine-tune performance on a
+                 board, or to compensate for external influences.
+
+For both PLL1 and PLL2 an optional child node can be used to specify spread
+spectrum clocking parameters for a board.
+  - spread-spectrum: SSC mode as defined in the data sheet.
+  - spread-spectrum-center: Use "centered" mode instead of "max" mode. When
+    present, the clock runs at the requested frequency on average. Otherwise
+    the requested frequency is the maximum value of the SCC range.
+
+
+Example:
+
+	clockgen: cdce925pw@64 {
+		compatible = "cdce925";
+		reg = <0x64>;
+		clocks = <&xtal_27Mhz>;
+		#clock-cells = <1>;
+		xtal-load-pf = <5>;
+		/* PLL options to get SSC 1% centered */
+		PLL2 {
+			spread-spectrum = <4>;
+			spread-spectrum-center;
+		};
+	};