“RTC device tree configuration”的版本间的差异
| 第6行： | 第6行： | ||
== DT bindings documentation == | == DT bindings documentation == | ||
| − | + | [[RTC internal peripheral|'''RTC''']]由“ STM32 RTC设备树绑定”表示<ref>{{CodeSource | Linux kernel | Documentation/devicetree/bindings/rtc/st,stm32-rtc.txt | Device tree bindings}}</ref> | |
== DT configuration == | == DT configuration == | ||
2020年11月10日 (二) 09:54的版本
目录
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 configuration
This hardware description is a combination of the STM32 microprocessor device tree files (.dtsi extension) and board device tree files (.dts extension). See the Device tree for an explanation of the device tree file split.
STM32CubeMX can be used to generate the board device tree. Refer to How to configure the DT using STM32CubeMX for more details.
DT configuration (STM32 level)
The RTC node is declared in the file stm32mp157c.dtsi [2]. It describes the hardware register address, clocks and interrupts.
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";
};
 |
This device tree part is related to STM32 microprocessors. It should be kept as is, without being modified by the end-user. |
DT configuration (board level)
This part is used to enable the RTC used on a board, which is done by setting the status property to okay.
An "st,lsco" property is available to select and enable the RTC output on which RTC low-speed clock is output. The valid ouput values are defined in [3]. A pinctrl state named "default" can be defined to reserve a pin for the RTC output.
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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