- Last edited 3 weeks ago ago
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 .
2 System overview
2.1 Component description
- RTC (hardware)
- RTC dedicated hardware block in STM32MPU product.
- RTC ST driver.
- 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 .
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
- rtc-stm32: drivers/rtc/rtc-stm32.c
- api: include/linux/rtc.h
- device-tree bindings constants: include/dt-bindings/rtc/rtc-stm32.h