RTC overview

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Applicable for

STM32MP13x lines, STM32MP15x lines

This article gives information about the Linux^® RTC framework. The RTC framework is involved in precise time countdown.

1 Framework purpose[edit source]

The RTC keeps the system time up-to-date and can wake up the system from the standby power mode at a programmed time.

A general presentation of the RTC framework is available in the Linux RTC documentation ^[1].

2 System overview[edit source]

2.1 Component description[edit source]

RTC (hardware)

RTC dedicated hardware block in STM32MPU product.

rtc-stm32

RTC ST driver.

rtc

Linux RTC framework, it provides API to RTC driver and interfaces to user.

Sysfs interface

Sysfs interface is accessible via /sys/class/rtc/rtcX/.

Procfs interface

Procfs interface is accessible via /proc/driver/rtc.

Char device interface

Device interface is accessible via /dev/rtcX.

User application

The user application can be a user built application or an community application such as hwclock.

2.2 API description[edit source]

API is described in Linux RTC documentation ^[1].

3 Configuration[edit source]

3.1 Kernel configuration[edit source]

Activate rtc-stm32 driver in kernel configuration using the Linux Menuconfig tool: Menuconfig or how to configure kernel

Device drivers  --->
    -*- Real Time Clock  --->
        <*> STM32 RTC

3.2 Device tree configuration[edit source]

Refer to the RTC device tree configuration.

4 How to use the framework[edit source]

Refer to the How to use the RTC.

5 How to trace and debug the framework[edit source]

5.1 How to trace[edit source]

Dynamic debug traces can be added using the following command:

echo -n 'file rtc-stm32.c +p'>/sys/kernel/debug/dynamic_debug/control

6 Source code location[edit source]

rtc-stm32: drivers/rtc/rtc-stm32.c
api: include/linux/rtc.h
framework:
device-tree bindings constants: include/dt-bindings/rtc/rtc-stm32.h

7 References[edit source]

↑ ^1.0 ^1.1 Linux RTC documentation

[Linux_RTC_documentation-1] 1.0 ^1.1 Linux RTC documentation

[1]