dt-bindings: clock: Add silabs,si5341

Adds the devicetree bindings for the Si5341 and Si5340 chips from
Silicon Labs. These are multiple-input multiple-output clock
synthesizers.
Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Documentation/devicetree/bindings/clock/silabs,si5341.txt

+Binding for Silicon Labs Si5341 and Si5340 programmable i2c clock generator.
+
+Reference
+[1] Si5341 Data Sheet
+    https://www.silabs.com/documents/public/data-sheets/Si5341-40-D-DataSheet.pdf
+[2] Si5341 Reference Manual
+    https://www.silabs.com/documents/public/reference-manuals/Si5341-40-D-RM.pdf
+
+The Si5341 and Si5340 are programmable i2c clock generators with up to 10 output
+clocks. The chip contains a PLL that sources 5 (or 4) multisynth clocks, which
+in turn can be directed to any of the 10 (or 4) outputs through a divider.
+The internal structure of the clock generators can be found in [2].
+
+The driver can be used in "as is" mode, reading the current settings from the
+chip at boot, in case you have a (pre-)programmed device. If the PLL is not
+configured when the driver probes, it assumes the driver must fully initialize
+it.
+
+The device type, speed grade and revision are determined runtime by probing.
+
+The driver currently only supports XTAL input mode, and does not support any
+fancy input configurations. They can still be programmed into the chip and
+the driver will leave them "as is".
+
+==I2C device node==
+
+Required properties:
+- compatible: shall be one of the following:
+	"silabs,si5340" - Si5340 A/B/C/D
+	"silabs,si5341" - Si5341 A/B/C/D
+- reg: i2c device address, usually 0x74
+- #clock-cells: from common clock binding; shall be set to 2.
+	The first value is "0" for outputs, "1" for synthesizers.
+	The second value is the output or synthesizer index.
+- clocks: from common clock binding; list of parent clock  handles,
+	corresponding to inputs. Use a fixed clock for the "xtal" input.
+	At least one must be present.
+- clock-names: One of: "xtal", "in0", "in1", "in2"
+- vdd-supply: Regulator node for VDD
+
+Optional properties:
+- vdda-supply: Regulator node for VDDA
+- vdds-supply: Regulator node for VDDS
+- silabs,pll-m-num, silabs,pll-m-den: Numerator and denominator for PLL
+  feedback divider. Must be such that the PLL output is in the valid range. For
+  example, to create 14GHz from a 48MHz xtal, use m-num=14000 and m-den=48. Only
+  the fraction matters, using 3500 and 12 will deliver the exact same result.
+  If these are not specified, and the PLL is not yet programmed when the driver
+  probes, the PLL will be set to 14GHz.
+- silabs,reprogram: When present, the driver will always assume the device must
+  be initialized, and always performs the soft-reset routine. Since this will
+  temporarily stop all output clocks, don't do this if the chip is generating
+  the CPU clock for example.
+- interrupts: Interrupt for INTRb pin.
+- #address-cells: shall be set to 1.
+- #size-cells: shall be set to 0.
+
+
+== Child nodes: Outputs ==
+
+The child nodes list the output clocks.
+
+Each of the clock outputs can be overwritten individually by using a child node.
+If a child node for a clock output is not set, the configuration remains
+unchanged.
+
+Required child node properties:
+- reg: number of clock output.
+
+Optional child node properties:
+- vdd-supply: Regulator node for VDD for this output. The driver selects default
+	values for common-mode and amplitude based on the voltage.
+- silabs,format: Output format, one of:
+	1 = differential (defaults to LVDS levels)
+	2 = low-power (defaults to HCSL levels)
+	4 = LVCMOS
+- silabs,common-mode: Manually override output common mode, see [2] for values
+- silabs,amplitude: Manually override output amplitude, see [2] for values
+- silabs,synth-master: boolean. If present, this output is allowed to change the
+	multisynth frequency dynamically.
+- silabs,silabs,disable-high: boolean. If set, the clock output is driven HIGH
+	when disabled, otherwise it's driven LOW.
+
+==Example==
+
+/* 48MHz reference crystal */
+ref48: ref48M {
+	compatible = "fixed-clock";
+	#clock-cells = <0>;
+	clock-frequency = <48000000>;
+};
+
+i2c-master-node {
+	/* Programmable clock (for logic) */
+	si5341: clock-generator@74 {
+		reg = <0x74>;
+		compatible = "silabs,si5341";
+		#clock-cells = <2>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		clocks = <&ref48>;
+		clock-names = "xtal";
+
+		silabs,pll-m-num = <14000>; /* PLL at 14.0 GHz */
+		silabs,pll-m-den = <48>;
+		silabs,reprogram; /* Chips are not programmed, always reset */
+
+		out@0 {
+			reg = <0>;
+			silabs,format = <1>; /* LVDS 3v3 */
+			silabs,common-mode = <3>;
+			silabs,amplitude = <3>;
+			silabs,synth-master;
+		};
+
+		/*
+		 * Output 6 configuration:
+		 *  LVDS 1v8
+		 */
+		out@6 {
+			reg = <6>;
+			silabs,format = <1>; /* LVDS 1v8 */
+			silabs,common-mode = <13>;
+			silabs,amplitude = <3>;
+		};
+
+		/*
+		 * Output 8 configuration:
+		 *  HCSL 3v3
+		 */
+		out@8 {
+			reg = <8>;
+			silabs,format = <2>;
+			silabs,common-mode = <11>;
+			silabs,amplitude = <3>;
+		};
+	};
+};
+
+some-video-node {
+	/* Standard clock bindings */
+	clock-names = "pixel";
+	clocks = <&si5341 0 7>; /* Output 7 */
+
+	/* Set output 7 to use syntesizer 3 as its parent */
+	assigned-clocks = <&si5341 0 7>, <&si5341 1 3>;
+	assigned-clock-parents = <&si5341 1 3>;
+	/* Set output 7 to 148.5 MHz using a synth frequency of 594 MHz */
+	assigned-clock-rates = <148500000>, <594000000>;
+};
+
+some-audio-node {
+	clock-names = "i2s-clk";
+	clocks = <&si5341 0 0>;
+	/*
+	 * since output 0 is a synth-master, the synth will be automatically set
+	 * to an appropriate frequency when the audio driver requests another
+	 * frequency. We give control over synth 2 to this output here.
+	 */
+	assigned-clocks = <&si5341 0 0>;
+	assigned-clock-parents = <&si5341 1 2>;
+};