How to use DMAMUX Synchronization ?

hi guys, i work on STM32 L4R5ZI without HAL functions.

I use DMA for LPUART(for HMI) and SPI (for component) and I want synchronize these communication with DMAMUX.

I see in the reference manual, some synchronization signals (EXTI, dmamux_evt,…), I wonder how to generate dmamux_evt0 for an internal synchronization.

Kindly guide me on this