// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
/* Copyright (C) 2018 Netronome Systems, Inc. */

#include <linux/bitfield.h>
#include <net/pkt_cls.h>

#include "../nfpcore/nfp_cpp.h"
#include "../nfp_app.h"
#include "../nfp_net_repr.h"
#include "main.h"

struct nfp_abm_u32_match {
        u32 handle;
        u32 band;
        u8 mask;
        u8 val;
        struct list_head list;
};

static bool
nfp_abm_u32_check_knode(struct nfp_abm *abm, struct tc_cls_u32_knode *knode,
                        __be16 proto, struct netlink_ext_ack *extack)
{
        struct tc_u32_key *k;
        unsigned int tos_off;

        if (knode->exts && tcf_exts_has_actions(knode->exts)) {
                NL_SET_ERR_MSG_MOD(extack, "action offload not supported");
                return false;
        }
        if (knode->link_handle) {
                NL_SET_ERR_MSG_MOD(extack, "linking not supported");
                return false;
        }
        if (knode->sel->flags != TC_U32_TERMINAL) {
                NL_SET_ERR_MSG_MOD(extack,
                                   "flags must be equal to TC_U32_TERMINAL");
                return false;
        }
        if (knode->sel->off || knode->sel->offshift || knode->sel->offmask ||
            knode->sel->offoff || knode->fshift) {
                NL_SET_ERR_MSG_MOD(extack, "variable offsetting not supported");
                return false;
        }
        if (knode->sel->hoff || knode->sel->hmask) {
                NL_SET_ERR_MSG_MOD(extack, "hashing not supported");
                return false;
        }
        if (knode->val || knode->mask) {
                NL_SET_ERR_MSG_MOD(extack, "matching on mark not supported");
                return false;
        }
        if (knode->res && knode->res->class) {
                NL_SET_ERR_MSG_MOD(extack, "setting non-0 class not supported");
                return false;
        }
        if (knode->res && knode->res->classid >= abm->num_bands) {
                NL_SET_ERR_MSG_MOD(extack,
                                   "classid higher than number of bands");
                return false;
        }
        if (knode->sel->nkeys != 1) {
                NL_SET_ERR_MSG_MOD(extack, "exactly one key required");
                return false;
        }

        switch (proto) {
        case htons(ETH_P_IP):
                tos_off = 16;
                break;
        case htons(ETH_P_IPV6):
                tos_off = 20;
                break;
        default:
                NL_SET_ERR_MSG_MOD(extack, "only IP and IPv6 supported as filter protocol");
                return false;
        }

        k = &knode->sel->keys[0];
        if (k->offmask) {
                NL_SET_ERR_MSG_MOD(extack, "offset mask - variable offsetting not supported");
                return false;
        }
        if (k->off) {
                NL_SET_ERR_MSG_MOD(extack, "only DSCP fields can be matched");
                return false;
        }
        if (k->val & ~k->mask) {
                NL_SET_ERR_MSG_MOD(extack, "mask does not cover the key");
                return false;
        }
        if (be32_to_cpu(k->mask) >> tos_off & ~abm->dscp_mask) {
                NL_SET_ERR_MSG_MOD(extack, "only high DSCP class selector bits can be used");
                nfp_err(abm->app->cpp,
                        "u32 offload: requested mask %x FW can support only %x\n",
                        be32_to_cpu(k->mask) >> tos_off, abm->dscp_mask);
                return false;
        }

        return true;
}

/* This filter list -> map conversion is O(n * m), we expect single digit or
 * low double digit number of prios and likewise for the filters.  Also u32
 * doesn't report stats, so it's really only setup time cost.
 */
static unsigned int
nfp_abm_find_band_for_prio(struct nfp_abm_link *alink, unsigned int prio)
{
        struct nfp_abm_u32_match *iter;

        list_for_each_entry(iter, &alink->dscp_map, list)
                if ((prio & iter->mask) == iter->val)
                        return iter->band;

        return alink->def_band;
}

static int nfp_abm_update_band_map(struct nfp_abm_link *alink)
{
        unsigned int i, bits_per_prio, prios_per_word, base_shift;
        struct nfp_abm *abm = alink->abm;
        u32 field_mask;

        alink->has_prio = !list_empty(&alink->dscp_map);

        bits_per_prio = roundup_pow_of_two(order_base_2(abm->num_bands));
        field_mask = (1 << bits_per_prio) - 1;
        prios_per_word = sizeof(u32) * BITS_PER_BYTE / bits_per_prio;

        /* FW mask applies from top bits */
        base_shift = 8 - order_base_2(abm->num_prios);

        for (i = 0; i < abm->num_prios; i++) {
                unsigned int offset;
                u32 *word;
                u8 band;

                word = &alink->prio_map[i / prios_per_word];
                offset = (i % prios_per_word) * bits_per_prio;

                band = nfp_abm_find_band_for_prio(alink, i << base_shift);

                *word &= ~(field_mask << offset);
                *word |= band << offset;
        }

        /* Qdisc offload status may change if has_prio changed */
        nfp_abm_qdisc_offload_update(alink);

        return nfp_abm_ctrl_prio_map_update(alink, alink->prio_map);
}

static void
nfp_abm_u32_knode_delete(struct nfp_abm_link *alink,
                         struct tc_cls_u32_knode *knode)
{
        struct nfp_abm_u32_match *iter;

        list_for_each_entry(iter, &alink->dscp_map, list)
                if (iter->handle == knode->handle) {
                        list_del(&iter->list);
                        kfree(iter);
                        nfp_abm_update_band_map(alink);
                        return;
                }
}

static int
nfp_abm_u32_knode_replace(struct nfp_abm_link *alink,
                          struct tc_cls_u32_knode *knode,
                          __be16 proto, struct netlink_ext_ack *extack)
{
        struct nfp_abm_u32_match *match = NULL, *iter;
        unsigned int tos_off;
        u8 mask, val;
        int err;

        if (!nfp_abm_u32_check_knode(alink->abm, knode, proto, extack))
                goto err_delete;

        tos_off = proto == htons(ETH_P_IP) ? 16 : 20;

        /* Extract the DSCP Class Selector bits */
        val = be32_to_cpu(knode->sel->keys[0].val) >> tos_off & 0xff;
        mask = be32_to_cpu(knode->sel->keys[0].mask) >> tos_off & 0xff;

        /* Check if there is no conflicting mapping and find match by handle */
        list_for_each_entry(iter, &alink->dscp_map, list) {
                u32 cmask;

                if (iter->handle == knode->handle) {
                        match = iter;
                        continue;
                }

                cmask = iter->mask & mask;
                if ((iter->val & cmask) == (val & cmask) &&
                    iter->band != knode->res->classid) {
                        NL_SET_ERR_MSG_MOD(extack, "conflict with already offloaded filter");
                        goto err_delete;
                }
        }

        if (!match) {
                match = kzalloc_obj(*match);
                if (!match)
                        return -ENOMEM;
                list_add(&match->list, &alink->dscp_map);
        }
        match->handle = knode->handle;
        match->band = knode->res->classid;
        match->mask = mask;
        match->val = val;

        err = nfp_abm_update_band_map(alink);
        if (err)
                goto err_delete;

        return 0;

err_delete:
        nfp_abm_u32_knode_delete(alink, knode);
        return -EOPNOTSUPP;
}

static int nfp_abm_setup_tc_block_cb(enum tc_setup_type type,
                                     void *type_data, void *cb_priv)
{
        struct tc_cls_u32_offload *cls_u32 = type_data;
        struct nfp_repr *repr = cb_priv;
        struct nfp_abm_link *alink;

        alink = repr->app_priv;

        if (type != TC_SETUP_CLSU32) {
                NL_SET_ERR_MSG_MOD(cls_u32->common.extack,
                                   "only offload of u32 classifier supported");
                return -EOPNOTSUPP;
        }
        if (!tc_cls_can_offload_and_chain0(repr->netdev, &cls_u32->common))
                return -EOPNOTSUPP;

        if (cls_u32->common.protocol != htons(ETH_P_IP) &&
            cls_u32->common.protocol != htons(ETH_P_IPV6)) {
                NL_SET_ERR_MSG_MOD(cls_u32->common.extack,
                                   "only IP and IPv6 supported as filter protocol");
                return -EOPNOTSUPP;
        }

        switch (cls_u32->command) {
        case TC_CLSU32_NEW_KNODE:
        case TC_CLSU32_REPLACE_KNODE:
                return nfp_abm_u32_knode_replace(alink, &cls_u32->knode,
                                                 cls_u32->common.protocol,
                                                 cls_u32->common.extack);
        case TC_CLSU32_DELETE_KNODE:
                nfp_abm_u32_knode_delete(alink, &cls_u32->knode);
                return 0;
        default:
                return -EOPNOTSUPP;
        }
}

static LIST_HEAD(nfp_abm_block_cb_list);

int nfp_abm_setup_cls_block(struct net_device *netdev, struct nfp_repr *repr,
                            struct flow_block_offload *f)
{
        return flow_block_cb_setup_simple(f, &nfp_abm_block_cb_list,
                                          nfp_abm_setup_tc_block_cb,
                                          repr, repr, true);
}