The platform management unit (PMU) in the Zynq UltraScale+ RFSoC device signals power domain changes using the PMU output pins. The Zynq UltraScale+ RFSoC device PMU GPO pins are connected to inputs of the MSP430 system controller via TXS0108E level-shifter U41. The RFSoC U1 bank 501 and MSP430 U42 pin numbers are listed in Table: XCZU28DR U1 to MSP430 Connections.
Through the I2C0 bus RFSoC MIO pins, the PMU has access to the board power controllers and power monitors. See This Figure for more details.
See the Zynq UltraScale+ Device Technical Reference Manual (UG1085) [Ref 3] for more details about the PMU interface.