xref: /freebsd/sys/contrib/device-tree/Bindings/clock/actions,owl-cmu.txt (revision c66ec88fed842fbaad62c30d510644ceb7bd2d71)

* Actions Semi Owl Clock Management Unit (CMU)

The Actions Semi Owl Clock Management Unit generates and supplies clock
to various controllers within the SoC. The clock binding described here is
applicable to S900, S700 and S500 SoC's.

Required Properties:

- compatible: should be one of the following,
	"actions,s900-cmu"
	"actions,s700-cmu"
	"actions,s500-cmu"
- reg: physical base address of the controller and length of memory mapped
  region.
- clocks: Reference to the parent clocks ("hosc", "losc")
- #clock-cells: should be 1.
- #reset-cells: should be 1.

Each clock is assigned an identifier, and client nodes can use this identifier
to specify the clock which they consume.

All available clocks are defined as preprocessor macros in corresponding
dt-bindings/clock/actions,s900-cmu.h or actions,s700-cmu.h or
actions,s500-cmu.h header and can be used in device tree sources.

External clocks:

The hosc clock used as input for the plls is generated outside the SoC. It is
expected that it is defined using standard clock bindings as "hosc".

Actions Semi S900 CMU also requires one more clock:
 - "losc" - internal low frequency oscillator

Example: Clock Management Unit node:

        cmu: clock-controller@e0160000 {
                compatible = "actions,s900-cmu";
                reg = <0x0 0xe0160000 0x0 0x1000>;
                clocks = <&hosc>, <&losc>;
                #clock-cells = <1>;
                #reset-cells = <1>;
        };

Example: UART controller node that consumes clock generated by the clock
management unit:

        uart: serial@e012a000 {
                compatible = "actions,s900-uart", "actions,owl-uart";
                reg = <0x0 0xe012a000 0x0 0x2000>;
                interrupts = <GIC_SPI 34 IRQ_TYPE_LEVEL_HIGH>;
                clocks = <&cmu CLK_UART5>;
        };