GITS_TYPER_DEVBITS
#define device_ids(its) (FIELD_GET(GITS_TYPER_DEVBITS, (its)->typer) + 1)
its->typer &= ~GITS_TYPER_DEVBITS;
its->typer |= FIELD_PREP(GITS_TYPER_DEVBITS, 20 - 1);
its->typer &= ~GITS_TYPER_DEVBITS;
its->typer |= FIELD_PREP(GITS_TYPER_DEVBITS, ids - 1);