BIU_SEMA
sema = ISP_READ(isp, BIU_SEMA);
ISP_WRITE(isp, BIU_SEMA, 0);
ISP_WRITE(isp, BIU_SEMA, 0);
ISP_WRITE(isp, BIU_SEMA, 0);
ISP_READ(isp, BIU_ISR), ISP_READ(isp, BIU_SEMA));
if (isp_pci_rd_debounced(isp, BIU_SEMA, &sema)) {
sema = BXR2(pcs, IspVirt2Off(isp, BIU_SEMA));
sema = BXR2(sbc, IspVirt2Off(isp, BIU_SEMA));