GICD_ICFGRn
const bus_size_t cfg_reg = GICD_ICFGRn(is->is_irq / 16);
#define GICv1_ICDICRn(n) GICD_ICFGRn(n)
icfg = gicd_read_4(sc, GICD_ICFGRn(is->is_irq / 16));
gicd_write_4(sc, GICD_ICFGRn(is->is_irq / 16), icfg);
gicd_write_4(sc, GICD_ICFGRn(n / 16), 0);