Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Silicon Labs/EFR32MG24A120F1536GM48/GPIO_S/PRS0_ASYNCH15ROUTE#0x0
ASYNCH15 port/pin select
ASYNCH15 port select register
ASYNCH15 pin select register
https://github.com/cmsis-svd/cmsis-svd-data