RTC device tree configuration

Article purpose

本文介绍了将 RTC internal peripheral 分配给 Linux^® OS. 时如何配置。 在这种情况下，它由RTC framework控制。

使用 device tree机制执行配置，该机制提供STM32 RTC Linux驱动程序使用的RTC外设的硬件描述。

DT bindings documentation

RTC由“ STM32 RTC设备树绑定”表示

DT configuration

该硬件描述是STM32微处理器设备树文件（扩展名为.dtsi）和板子设备树文件（扩展名为.dts）的组合。 有关设备树文件分割的说明，请参见 [[Device tree]。 STM32CubeMX可用于生成板卡设备树。 有关更多详细信息，请参考 How to configure the DT using STM32CubeMX.

DT configuration (STM32 level)

T在文件“ stm32mp157c.dtsi”中声明了 RTC节点. 它描述了硬件寄存器地址，时钟和中断。

rtc: rtc@5c004000 {
	compatible = "st,stm32mp1-rtc";
	reg = <0x5c004000 0x400>;                               --> Register location and length
	clocks = <&rcc RTCAPB>, <&rcc RTC>;
	clock-names = "pclk", "rtc_ck";
	interrupts-extended = <&intc GIC_SPI 3 IRQ_TYPE_LEVEL_HIGH>,
			      <&exti 19 1>;
	status = "disabled";
};

该设备树部分与STM32微处理器有关。 它应该保持原样，而不要由最终用户修改。

DT configuration (board level)

该部分用于启用板上使用的RTC，这是通过将 status属性设置为 okay来完成的。

“ st，lsco”属性可用于选择和启用在其上输出RTC低速时钟的RTC输出。 有效的输出值在. 中定义。 可以定义一个名为“默认”的pinctrl状态来为RTC输出保留一个引脚。

DT configuration examples

#include <dt-bindings/rtc/rtc-stm32.h>
...
&rtc {
	st,lsco = <RTC_OUT2_RMP>;
	pinctrl-0 = <&rtc_out2_rmp_pins_a>;
	pinctrl-names = "default";
};

How to configure the DT using STM32CubeMX

The STM32CubeMX tool can be used to configure the STM32MPU device and get the corresponding platform configuration device tree files.
STM32CubeMX might not support all the properties described in the above DT bindings documentation paragraph. If so, the tool inserts user sections in the generated device tree. These sections can then be edited to add some properties and they are preserved from one generation to another. Refer to STM32CubeMX user manual for further information.

References

Please refer to the following links for additional information:

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