Last edited 8 months ago

RTC overview

Applicable for STM32MP13x lines, STM32MP15x lines, STM32MP25x 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]

Alternate text

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]

7. References[edit source]