STM32MP1 support available in SW4STM32

   With System Workbench for Linux, Embedded Linux on the STM32MP1 family of MPUs from ST was never as simple to build and maintain, even for newcomers in the Linux world.
And, if you install System Workbench for Linux in System Workbench for STM32 you can seamlessly develop and debug asymmetric applications running partly on Linux, partly on the Cortex-M4; you can download a short video showcasing this on the ac6-tools website (registration required).

System Workbench for STM32

Generate Software Interrupt (SI) with STM32F· Discovery board with HAL drivers

likely you timer isnto configure corretcly
it is common to get the auto reloade or prescalewrong due to divider ( timer input clock is 2x the ahb clk)
25HZ 40ms
also they are a few +/- 1 to consider in the prescaler and ARR valeu that can make huge diffrence in final timer freq

i recomend you read http://www.st.com/web/en/resource/technical/document/application_note/DM00042534.pdfQuestion