isp_regs
isp->isp_regs = pcs->regs;
#define BXR2(isp, off) bus_read_2((isp)->isp_regs, (off))
#define BXW2(isp, off, v) bus_write_2((isp)->isp_regs, (off), (v))
#define BXR4(isp, off) bus_read_4((isp)->isp_regs, (off))
#define BXW4(isp, off, v) bus_write_4((isp)->isp_regs, (off), (v))