UIC_SR
mtdcr(uic->dcrbase + UIC_SR, sr);
mtdcr(uic->dcrbase + UIC_SR, ~mask);
mtdcr(uic->dcrbase + UIC_SR, 0xffffffff);
mtdcr(uic->dcrbase + UIC_SR, sr);
mtdcr(uic->dcrbase + UIC_SR, 1 << (31-src));