xref: /freebsd/sys/contrib/device-tree/Bindings/clock/st,stm32h7-rcc.txt (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a) 
1STMicroelectronics STM32H7 Reset and Clock Controller
2=====================================================
3
4The RCC IP is both a reset and a clock controller.
5
6Please refer to clock-bindings.txt for common clock controller binding usage.
7Please also refer to reset.txt for common reset controller binding usage.
8
9Required properties:
10- compatible: Should be:
11  "st,stm32h743-rcc"
12
13- reg: should be register base and length as documented in the
14  datasheet
15
16- #reset-cells: 1, see below
17
18- #clock-cells : from common clock binding; shall be set to 1
19
20- clocks: External oscillator clock phandle
21  - high speed external clock signal (HSE)
22  - low speed external clock signal (LSE)
23  - external I2S clock (I2S_CKIN)
24
25Optional properties:
26- st,syscfg: phandle for pwrcfg, mandatory to disable/enable backup domain
27  write protection (RTC clock).
28
29Example:
30
31	rcc: reset-clock-controller@58024400 {
32		compatible = "st,stm32h743-rcc", "st,stm32-rcc";
33		reg = <0x58024400 0x400>;
34		#reset-cells = <1>;
35		#clock-cells = <1>;
36		clocks = <&clk_hse>, <&clk_lse>, <&clk_i2s_ckin>;
37
38		st,syscfg = <&pwrcfg>;
39};
40
41The peripheral clock consumer should specify the desired clock by
42having the clock ID in its "clocks" phandle cell.
43
44Example:
45
46		timer5: timer@40000c00 {
47			compatible = "st,stm32-timer";
48			reg = <0x40000c00 0x400>;
49			interrupts = <50>;
50			clocks = <&rcc TIM5_CK>;
51		};
52
53Specifying softreset control of devices
54=======================================
55
56Device nodes should specify the reset channel required in their "resets"
57property, containing a phandle to the reset device node and an index specifying
58which channel to use.
59The index is the bit number within the RCC registers bank, starting from RCC
60base address.
61It is calculated as: index = register_offset / 4 * 32 + bit_offset.
62Where bit_offset is the bit offset within the register.
63
64For example, for CRC reset:
65  crc = AHB4RSTR_offset / 4 * 32 + CRCRST_bit_offset = 0x88 / 4 * 32 + 19 = 1107
66
67Example:
68
69	timer2 {
70		resets	= <&rcc STM32H7_APB1L_RESET(TIM2)>;
71	};
72