armgic_ipl_to_priority
gicc_write(sc, GICC_PMR, armgic_ipl_to_priority(ipl));
gicc_write(sc, GICC_PMR, armgic_ipl_to_priority(old_ipl));
gicc_write(sc, GICC_PMR, armgic_ipl_to_priority(ipl));
priority |= armgic_ipl_to_priority(is->is_ipl) << byte_shift;
priority |= armgic_ipl_to_priority(is->is_ipl) << byte_shift;
gicc_write(sc, GICC_PMR, armgic_ipl_to_priority(ci->ci_cpl)); // set PMR