st,stm32h7-rcc

Vendor: STMicroelectronics

Description

STM32 Reset and Clock controller node for STM32H7 devices
This node is in charge of system clock ('SYSCLK') source selection and
System Clock Generation.

Configuring STM32 Reset and Clock controller node:

System clock source should be selected amongst the clock nodes available in "clocks"
node (typically 'clk_hse, clk_csi', 'pll', ...).
As part of this node configuration, SYSCLK frequency should also be defined, using
"clock-frequency" property.
Last, bus clocks (typically HCLK, PCLK1, PCLK2) should be configured using matching
prescaler properties.
Here is an example of correctly configured rcc node:
&rcc {
         clocks = <&pll>;  /* Set pll as SYSCLK source */
         clock-frequency = <DT_FREQ_M(480)>; /* SYSCLK runs at 480MHz */
         d1cpre = <1>;
         hpre = <1>;
         d1ppre = <1>;
         d2ppre1 = <1>;
         d2ppre2 = <1>;
         d3ppre = <1>;
}

Specifying a gated clock:

To specify a gated clock, a peripheral should define a "clocks" property encoded
in the following way:
... {
         ...
         clocks = <&rcc STM32_CLOCK_BUS_APB2 0x00000020>;
         ...
}
After the phandle referring to rcc node, the first index specifies the registers of
the bus controlling the peripheral and the second index specifies the bit used to
control the peripheral clock in that bus register.

Properties

Properties not inherited from the base binding file.

Name

Type

Details

#clock-cells

int

 
Number of items to expect in a Clock specifier

This property is required.

Constant value: 2

clock-frequency

int

 
default frequency in Hz for clock output

This property is required.

d1cpre

int

 
D1 Domain, CPU1 clock prescaler. Sets a HCLK frequency (feeding Cortex-M Systick)
lower than SYSCLK frequency (actual core frequency).
Zephyr doesn't make a difference today between these two clocks.
Changing this prescaler is not allowed until it is made possible to
use them independently in Zephyr clock subsystem.

This property is required.

Legal values: 1

hpre

int

 
D2 domain, CPU2 core clock and AHB(1/2/3/4) peripheral prescaler

This property is required.

Legal values: 1, 2, 4, 8, 16, 64, 128, 256, 512

d1ppre

int

 
D1 domain, APB3 peripheral prescaler

This property is required.

Legal values: 1, 2, 4, 8, 16

d2ppre1

int

 
D2 domain, APB1 peripheral prescaler

This property is required.

Legal values: 1, 2, 4, 8, 16

d2ppre2

int

 
D2 domain, APB2 peripheral prescaler

This property is required.

Legal values: 1, 2, 4, 8, 16

d3ppre

int

 
D3 domain, APB4 peripheral prescaler

This property is required.

Legal values: 1, 2, 4, 8, 16

Specifier cell names

  • clock cells: bus, bits