nfp_rtsym_readl
err = nfp_rtsym_readl(pf->cpp, pf->mbox, NFP_MBOX_CMD, &val);
err = nfp_rtsym_readl(pf->cpp, pf->mbox, NFP_MBOX_DATA_LEN, &val);
err = nfp_rtsym_readl(pf->cpp, pf->mbox, NFP_MBOX_CMD, &val);
err = nfp_rtsym_readl(pf->cpp, pf->mbox, NFP_MBOX_DATA_LEN, &val);
err = nfp_rtsym_readl(pf->cpp, pf->mbox, NFP_MBOX_RET, &val);
int nfp_rtsym_readl(struct nfp_cpp *cpp, const struct nfp_rtsym *sym, u64 off,
err = nfp_rtsym_readl(rtbl->cpp, sym, 0, &val32);