ref: 9b68b426103ca0564d522d9918082125836a9f23
dir: /sys/src/9/arm64/io.h/
enum {
IRQfiq = -1,
PPI = 16,
SPI = 32,
IRQcntvns = PPI+11,
IRQuart = SPI+1,
IRQpci1 = SPI+3,
IRQpci2 = SPI+4,
IRQpci3 = SPI+5,
IRQpci4 = SPI+6,
};
#define BUSUNKNOWN (-1)