CHIP-linux-libre/Documentation/devicetree/bindings/clock/st,stm32-rcc.txt

STMicroelectronics STM32 Reset and Clock Controller
===================================================

The RCC IP is both a reset and a clock controller. This documentation only
describes the clock part.

Please also refer to clock-bindings.txt in this directory for common clock
controller binding usage.

Required properties:
- compatible: Should be "st,stm32f42xx-rcc"
- reg: should be register base and length as documented in the
  datasheet
- #clock-cells: 2, device nodes should specify the clock in their "clocks"
  property, containing a phandle to the clock device node, an index selecting
  between gated clocks and other clocks and an index specifying the clock to
  use.

Example:

	rcc: rcc@40023800 {
		#clock-cells = <2>
		compatible = "st,stm32f42xx-rcc", "st,stm32-rcc";
		reg = <0x40023800 0x400>;
	};

Specifying gated clocks
=======================

The primary index must be set to 0.

The secondary index is the bit number within the RCC register bank, starting
from the first RCC clock enable register (RCC_AHB1ENR, address offset 0x30).

It is calculated as: index = register_offset / 4 * 32 + bit_offset.
Where bit_offset is the bit offset within the register (LSB is 0, MSB is 31).

Example:

	/* Gated clock, AHB1 bit 0 (GPIOA) */
	... {
		clocks = <&rcc 0 0>
	};

	/* Gated clock, AHB2 bit 4 (CRYP) */
	... {
		clocks = <&rcc 0 36>
	};

Specifying other clocks
=======================

The primary index must be set to 1.

The secondary index is bound with the following magic numbers:

	0	SYSTICK
	1	FCLK

Example:

	/* Misc clock, FCLK */
	... {
		clocks = <&rcc 1 1>
	};