nviic_write
void nviic_write(struct nviic_controller *, bus_size_t, u_int8_t);
nviic_write(nc, NVI_SMB_ADDR, addr << 1);
nviic_write(nc, NVI_SMB_CMD, b[0]);
nviic_write(nc, NVI_SMB_DATA(i), b[i]);
nviic_write(nc, NVI_SMB_PRTCL, protocol);