1. Article purpose[edit source]
The purpose of this article is to explain how to monitor HSE oscillator.
If HSE oscillator is used in the clock tree, it is possible to enable a monitoring to detect and avoid over frequency. The LPTIM mechanism will detect an over frequency and trig a tamper event which runs some custom actions.
2. How to activate the monitoring[edit source]
By default, the HSE monitor is disabled in dtsi "SoC" files.
To activate HSE monitor, add this node in your board OP-TEE device tree
&hse_monitor {
status = "okay";
};