st,stm32-rcc

Vendor: STMicroelectronics

Description

STM32 Reset and Clock controller node.
This node is in charge of system clock ('SYSCLK') source selection and controlling
clocks for AHB (Advanced High Performance) and APB (Advanced Peripheral) bus domains.

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_hsi', '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(80)>; /* SYSCLK runs at 80MHz */
         ahb-prescaler = <1>;
         apb1-presacler = <1>;
         apb2-presacler = <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

Node specific propertiesDeprecated node specific propertiesBase 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.
ahb-prescaler	int	AHB prescaler. Sets a HCLK frequency (feeding Cortex-M Systick) lower than SYSCLK frequency (actual core frequency). The HCLK clocks CPU, AHB, memories and DMA. This property is required. Legal values: 1, 2, 4, 8, 16, 64, 128, 256, 512
apb1-prescaler	int	This property is required. Legal values: 1, 2, 4, 8, 16
apb2-prescaler	int	This property is required. Legal values: 1, 2, 4, 8, 16

Specifier cell names

• clock cells: bus, bits