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> };