RTC overview

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

1 Framework purpose

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

Alternate text

2.1 Component description

  • 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 an user built application or an community application like hwclock.

2.2 API description

API is described in Linux RTC documentation [1].

3 Configuration

3.1 Kernel Configuration

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

Please refer to the RTC device tree configuration.

4 How to use the framework

Please refer to the How to use the RTC.

5 How to trace and debug the framework

5.1 How to trace

Dynamic debug traces can be added using the following commands:

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

6 Source code location

7 References