net: dsa: tag_sja1105: stop asking the sja1105 driver in sja1105_xmit_tpid

[mirror_ubuntu-jammy-kernel.git] / net / dsa / tag_sja1105.c

// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2019, Vladimir Oltean <olteanv@gmail.com>
 */
#include <linux/if_vlan.h>
#include <linux/dsa/sja1105.h>
#include <linux/dsa/8021q.h>
#include <linux/packing.h>
#include "dsa_priv.h"

/* Is this a TX or an RX header? */
#define SJA1110_HEADER_HOST_TO_SWITCH           BIT(15)

/* RX header */
#define SJA1110_RX_HEADER_IS_METADATA           BIT(14)
#define SJA1110_RX_HEADER_HOST_ONLY             BIT(13)
#define SJA1110_RX_HEADER_HAS_TRAILER           BIT(12)

/* Trap-to-host format (no trailer present) */
#define SJA1110_RX_HEADER_SRC_PORT(x)           (((x) & GENMASK(7, 4)) >> 4)
#define SJA1110_RX_HEADER_SWITCH_ID(x)          ((x) & GENMASK(3, 0))

/* Timestamp format (trailer present) */
#define SJA1110_RX_HEADER_TRAILER_POS(x)        ((x) & GENMASK(11, 0))

#define SJA1110_RX_TRAILER_SWITCH_ID(x)         (((x) & GENMASK(7, 4)) >> 4)
#define SJA1110_RX_TRAILER_SRC_PORT(x)          ((x) & GENMASK(3, 0))

/* Meta frame format (for 2-step TX timestamps) */
#define SJA1110_RX_HEADER_N_TS(x)               (((x) & GENMASK(8, 4)) >> 4)

/* TX header */
#define SJA1110_TX_HEADER_UPDATE_TC             BIT(14)
#define SJA1110_TX_HEADER_TAKE_TS               BIT(13)
#define SJA1110_TX_HEADER_TAKE_TS_CASC          BIT(12)
#define SJA1110_TX_HEADER_HAS_TRAILER           BIT(11)

/* Only valid if SJA1110_TX_HEADER_HAS_TRAILER is false */
#define SJA1110_TX_HEADER_PRIO(x)               (((x) << 7) & GENMASK(10, 7))
#define SJA1110_TX_HEADER_TSTAMP_ID(x)          ((x) & GENMASK(7, 0))

/* Only valid if SJA1110_TX_HEADER_HAS_TRAILER is true */
#define SJA1110_TX_HEADER_TRAILER_POS(x)        ((x) & GENMASK(10, 0))

#define SJA1110_TX_TRAILER_TSTAMP_ID(x)         (((x) << 24) & GENMASK(31, 24))
#define SJA1110_TX_TRAILER_PRIO(x)              (((x) << 21) & GENMASK(23, 21))
#define SJA1110_TX_TRAILER_SWITCHID(x)          (((x) << 12) & GENMASK(15, 12))
#define SJA1110_TX_TRAILER_DESTPORTS(x)         (((x) << 1) & GENMASK(11, 1))

#define SJA1110_META_TSTAMP_SIZE                10

#define SJA1110_HEADER_LEN                      4
#define SJA1110_RX_TRAILER_LEN                  13
#define SJA1110_TX_TRAILER_LEN                  4
#define SJA1110_MAX_PADDING_LEN                 15

/* Similar to is_link_local_ether_addr(hdr->h_dest) but also covers PTP */
static inline bool sja1105_is_link_local(const struct sk_buff *skb)
{
        const struct ethhdr *hdr = eth_hdr(skb);
        u64 dmac = ether_addr_to_u64(hdr->h_dest);

        if (ntohs(hdr->h_proto) == ETH_P_SJA1105_META)
                return false;
        if ((dmac & SJA1105_LINKLOCAL_FILTER_A_MASK) ==
                    SJA1105_LINKLOCAL_FILTER_A)
                return true;
        if ((dmac & SJA1105_LINKLOCAL_FILTER_B_MASK) ==
                    SJA1105_LINKLOCAL_FILTER_B)
                return true;
        return false;
}

struct sja1105_meta {
        u64 tstamp;
        u64 dmac_byte_4;
        u64 dmac_byte_3;
        u64 source_port;
        u64 switch_id;
};

static void sja1105_meta_unpack(const struct sk_buff *skb,
                                struct sja1105_meta *meta)
{
        u8 *buf = skb_mac_header(skb) + ETH_HLEN;

        /* UM10944.pdf section 4.2.17 AVB Parameters:
         * Structure of the meta-data follow-up frame.
         * It is in network byte order, so there are no quirks
         * while unpacking the meta frame.
         *
         * Also SJA1105 E/T only populates bits 23:0 of the timestamp
         * whereas P/Q/R/S does 32 bits. Since the structure is the
         * same and the E/T puts zeroes in the high-order byte, use
         * a unified unpacking command for both device series.
         */
        packing(buf,     &meta->tstamp,     31, 0, 4, UNPACK, 0);
        packing(buf + 4, &meta->dmac_byte_4, 7, 0, 1, UNPACK, 0);
        packing(buf + 5, &meta->dmac_byte_3, 7, 0, 1, UNPACK, 0);
        packing(buf + 6, &meta->source_port, 7, 0, 1, UNPACK, 0);
        packing(buf + 7, &meta->switch_id,   7, 0, 1, UNPACK, 0);
}

static inline bool sja1105_is_meta_frame(const struct sk_buff *skb)
{
        const struct ethhdr *hdr = eth_hdr(skb);
        u64 smac = ether_addr_to_u64(hdr->h_source);
        u64 dmac = ether_addr_to_u64(hdr->h_dest);

        if (smac != SJA1105_META_SMAC)
                return false;
        if (dmac != SJA1105_META_DMAC)
                return false;
        if (ntohs(hdr->h_proto) != ETH_P_SJA1105_META)
                return false;
        return true;
}

/* Calls sja1105_port_deferred_xmit in sja1105_main.c */
static struct sk_buff *sja1105_defer_xmit(struct dsa_port *dp,
                                          struct sk_buff *skb)
{
        struct sja1105_port *sp = dp->priv;

        if (!dsa_port_is_sja1105(dp))
                return skb;

        /* Increase refcount so the kfree_skb in dsa_slave_xmit
         * won't really free the packet.
         */
        skb_queue_tail(&sp->xmit_queue, skb_get(skb));
        kthread_queue_work(sp->xmit_worker, &sp->xmit_work);

        return NULL;
}

/* Send VLAN tags with a TPID that blends in with whatever VLAN protocol a
 * bridge spanning ports of this switch might have.
 */
static u16 sja1105_xmit_tpid(struct dsa_port *dp)
{
        struct dsa_switch *ds = dp->ds;
        struct dsa_port *other_dp;
        u16 proto;

        /* Since VLAN awareness is global, then if this port is VLAN-unaware,
         * all ports are. Use the VLAN-unaware TPID used for tag_8021q.
         */
        if (!dsa_port_is_vlan_filtering(dp))
                return ETH_P_SJA1105;

        /* Port is VLAN-aware, so there is a bridge somewhere (a single one,
         * we're sure about that). It may not be on this port though, so we
         * need to find it.
         */
        list_for_each_entry(other_dp, &ds->dst->ports, list) {
                if (other_dp->ds != ds)
                        continue;

                if (!other_dp->bridge_dev)
                        continue;

                /* Error is returned only if CONFIG_BRIDGE_VLAN_FILTERING,
                 * which seems pointless to handle, as our port cannot become
                 * VLAN-aware in that case.
                 */
                br_vlan_get_proto(other_dp->bridge_dev, &proto);

                return proto;
        }

        WARN_ONCE(1, "Port is VLAN-aware but cannot find associated bridge!\n");

        return ETH_P_SJA1105;
}

static struct sk_buff *sja1105_imprecise_xmit(struct sk_buff *skb,
                                              struct net_device *netdev)
{
        struct dsa_port *dp = dsa_slave_to_port(netdev);
        struct net_device *br = dp->bridge_dev;
        u16 tx_vid;

        /* If the port is under a VLAN-aware bridge, just slide the
         * VLAN-tagged packet into the FDB and hope for the best.
         * This works because we support a single VLAN-aware bridge
         * across the entire dst, and its VLANs cannot be shared with
         * any standalone port.
         */
        if (br_vlan_enabled(br))
                return skb;

        /* If the port is under a VLAN-unaware bridge, use an imprecise
         * TX VLAN that targets the bridge's entire broadcast domain,
         * instead of just the specific port.
         */
        tx_vid = dsa_8021q_bridge_tx_fwd_offload_vid(dp->bridge_num);

        return dsa_8021q_xmit(skb, netdev, sja1105_xmit_tpid(dp), tx_vid);
}

/* Transform untagged control packets into pvid-tagged control packets so that
 * all packets sent by this tagger are VLAN-tagged and we can configure the
 * switch to drop untagged packets coming from the DSA master.
 */
static struct sk_buff *sja1105_pvid_tag_control_pkt(struct dsa_port *dp,
                                                    struct sk_buff *skb, u8 pcp)
{
        __be16 xmit_tpid = htons(sja1105_xmit_tpid(dp));
        struct vlan_ethhdr *hdr;

        /* If VLAN tag is in hwaccel area, move it to the payload
         * to deal with both cases uniformly and to ensure that
         * the VLANs are added in the right order.
         */
        if (unlikely(skb_vlan_tag_present(skb))) {
                skb = __vlan_hwaccel_push_inside(skb);
                if (!skb)
                        return NULL;
        }

        hdr = (struct vlan_ethhdr *)skb_mac_header(skb);

        /* If skb is already VLAN-tagged, leave that VLAN ID in place */
        if (hdr->h_vlan_proto == xmit_tpid)
                return skb;

        return vlan_insert_tag(skb, xmit_tpid, (pcp << VLAN_PRIO_SHIFT) |
                               SJA1105_DEFAULT_VLAN);
}

static struct sk_buff *sja1105_xmit(struct sk_buff *skb,
                                    struct net_device *netdev)
{
        struct dsa_port *dp = dsa_slave_to_port(netdev);
        u16 tx_vid = dsa_8021q_tx_vid(dp->ds, dp->index);
        u16 queue_mapping = skb_get_queue_mapping(skb);
        u8 pcp = netdev_txq_to_tc(netdev, queue_mapping);

        if (skb->offload_fwd_mark)
                return sja1105_imprecise_xmit(skb, netdev);

        /* Transmitting management traffic does not rely upon switch tagging,
         * but instead SPI-installed management routes. Part 2 of this
         * is the .port_deferred_xmit driver callback.
         */
        if (unlikely(sja1105_is_link_local(skb))) {
                skb = sja1105_pvid_tag_control_pkt(dp, skb, pcp);
                if (!skb)
                        return NULL;

                return sja1105_defer_xmit(dp, skb);
        }

        return dsa_8021q_xmit(skb, netdev, sja1105_xmit_tpid(dp),
                             ((pcp << VLAN_PRIO_SHIFT) | tx_vid));
}

static struct sk_buff *sja1110_xmit(struct sk_buff *skb,
                                    struct net_device *netdev)
{
        struct sk_buff *clone = SJA1105_SKB_CB(skb)->clone;
        struct dsa_port *dp = dsa_slave_to_port(netdev);
        u16 tx_vid = dsa_8021q_tx_vid(dp->ds, dp->index);
        u16 queue_mapping = skb_get_queue_mapping(skb);
        u8 pcp = netdev_txq_to_tc(netdev, queue_mapping);
        __be32 *tx_trailer;
        __be16 *tx_header;
        int trailer_pos;

        if (skb->offload_fwd_mark)
                return sja1105_imprecise_xmit(skb, netdev);

        /* Transmitting control packets is done using in-band control
         * extensions, while data packets are transmitted using
         * tag_8021q TX VLANs.
         */
        if (likely(!sja1105_is_link_local(skb)))
                return dsa_8021q_xmit(skb, netdev, sja1105_xmit_tpid(dp),
                                     ((pcp << VLAN_PRIO_SHIFT) | tx_vid));

        skb = sja1105_pvid_tag_control_pkt(dp, skb, pcp);
        if (!skb)
                return NULL;

        skb_push(skb, SJA1110_HEADER_LEN);

        dsa_alloc_etype_header(skb, SJA1110_HEADER_LEN);

        trailer_pos = skb->len;

        tx_header = dsa_etype_header_pos_tx(skb);
        tx_trailer = skb_put(skb, SJA1110_TX_TRAILER_LEN);

        tx_header[0] = htons(ETH_P_SJA1110);
        tx_header[1] = htons(SJA1110_HEADER_HOST_TO_SWITCH |
                             SJA1110_TX_HEADER_HAS_TRAILER |
                             SJA1110_TX_HEADER_TRAILER_POS(trailer_pos));
        *tx_trailer = cpu_to_be32(SJA1110_TX_TRAILER_PRIO(pcp) |
                                  SJA1110_TX_TRAILER_SWITCHID(dp->ds->index) |
                                  SJA1110_TX_TRAILER_DESTPORTS(BIT(dp->index)));
        if (clone) {
                u8 ts_id = SJA1105_SKB_CB(clone)->ts_id;

                tx_header[1] |= htons(SJA1110_TX_HEADER_TAKE_TS);
                *tx_trailer |= cpu_to_be32(SJA1110_TX_TRAILER_TSTAMP_ID(ts_id));
        }

        return skb;
}

static void sja1105_transfer_meta(struct sk_buff *skb,
                                  const struct sja1105_meta *meta)
{
        struct ethhdr *hdr = eth_hdr(skb);

        hdr->h_dest[3] = meta->dmac_byte_3;
        hdr->h_dest[4] = meta->dmac_byte_4;
        SJA1105_SKB_CB(skb)->tstamp = meta->tstamp;
}

/* This is a simple state machine which follows the hardware mechanism of
 * generating RX timestamps:
 *
 * After each timestampable skb (all traffic for which send_meta1 and
 * send_meta0 is true, aka all MAC-filtered link-local traffic) a meta frame
 * containing a partial timestamp is immediately generated by the switch and
 * sent as a follow-up to the link-local frame on the CPU port.
 *
 * The meta frames have no unique identifier (such as sequence number) by which
 * one may pair them to the correct timestampable frame.
 * Instead, the switch has internal logic that ensures no frames are sent on
 * the CPU port between a link-local timestampable frame and its corresponding
 * meta follow-up. It also ensures strict ordering between ports (lower ports
 * have higher priority towards the CPU port). For this reason, a per-port
 * data structure is not needed/desirable.
 *
 * This function pairs the link-local frame with its partial timestamp from the
 * meta follow-up frame. The full timestamp will be reconstructed later in a
 * work queue.
 */
static struct sk_buff
*sja1105_rcv_meta_state_machine(struct sk_buff *skb,
                                struct sja1105_meta *meta,
                                bool is_link_local,
                                bool is_meta)
{
        /* Step 1: A timestampable frame was received.
         * Buffer it until we get its meta frame.
         */
        if (is_link_local) {
                struct dsa_port *dp = dsa_slave_to_port(skb->dev);
                struct sja1105_port *sp = dp->priv;

                if (unlikely(!dsa_port_is_sja1105(dp)))
                        return skb;

                if (!test_bit(SJA1105_HWTS_RX_EN, &sp->data->state))
                        /* Do normal processing. */
                        return skb;

                spin_lock(&sp->data->meta_lock);
                /* Was this a link-local frame instead of the meta
                 * that we were expecting?
                 */
                if (sp->data->stampable_skb) {
                        dev_err_ratelimited(dp->ds->dev,
                                            "Expected meta frame, is %12llx "
                                            "in the DSA master multicast filter?\n",
                                            SJA1105_META_DMAC);
                        kfree_skb(sp->data->stampable_skb);
                }

                /* Hold a reference to avoid dsa_switch_rcv
                 * from freeing the skb.
                 */
                sp->data->stampable_skb = skb_get(skb);
                spin_unlock(&sp->data->meta_lock);

                /* Tell DSA we got nothing */
                return NULL;

        /* Step 2: The meta frame arrived.
         * Time to take the stampable skb out of the closet, annotate it
         * with the partial timestamp, and pretend that we received it
         * just now (basically masquerade the buffered frame as the meta
         * frame, which serves no further purpose).
         */
        } else if (is_meta) {
                struct dsa_port *dp = dsa_slave_to_port(skb->dev);
                struct sja1105_port *sp = dp->priv;
                struct sk_buff *stampable_skb;

                if (unlikely(!dsa_port_is_sja1105(dp)))
                        return skb;

                /* Drop the meta frame if we're not in the right state
                 * to process it.
                 */
                if (!test_bit(SJA1105_HWTS_RX_EN, &sp->data->state))
                        return NULL;

                spin_lock(&sp->data->meta_lock);

                stampable_skb = sp->data->stampable_skb;
                sp->data->stampable_skb = NULL;

                /* Was this a meta frame instead of the link-local
                 * that we were expecting?
                 */
                if (!stampable_skb) {
                        dev_err_ratelimited(dp->ds->dev,
                                            "Unexpected meta frame\n");
                        spin_unlock(&sp->data->meta_lock);
                        return NULL;
                }

                if (stampable_skb->dev != skb->dev) {
                        dev_err_ratelimited(dp->ds->dev,
                                            "Meta frame on wrong port\n");
                        spin_unlock(&sp->data->meta_lock);
                        return NULL;
                }

                /* Free the meta frame and give DSA the buffered stampable_skb
                 * for further processing up the network stack.
                 */
                kfree_skb(skb);
                skb = stampable_skb;
                sja1105_transfer_meta(skb, meta);

                spin_unlock(&sp->data->meta_lock);
        }

        return skb;
}

static bool sja1105_skb_has_tag_8021q(const struct sk_buff *skb)
{
        u16 tpid = ntohs(eth_hdr(skb)->h_proto);

        return tpid == ETH_P_SJA1105 || tpid == ETH_P_8021Q ||
               skb_vlan_tag_present(skb);
}

static bool sja1110_skb_has_inband_control_extension(const struct sk_buff *skb)
{
        return ntohs(eth_hdr(skb)->h_proto) == ETH_P_SJA1110;
}

/* If the VLAN in the packet is a tag_8021q one, set @source_port and
 * @switch_id and strip the header. Otherwise set @vid and keep it in the
 * packet.
 */
static void sja1105_vlan_rcv(struct sk_buff *skb, int *source_port,
                             int *switch_id, u16 *vid)
{
        struct vlan_ethhdr *hdr = (struct vlan_ethhdr *)skb_mac_header(skb);
        u16 vlan_tci;

        if (skb_vlan_tag_present(skb))
                vlan_tci = skb_vlan_tag_get(skb);
        else
                vlan_tci = ntohs(hdr->h_vlan_TCI);

        if (vid_is_dsa_8021q_rxvlan(vlan_tci & VLAN_VID_MASK))
                return dsa_8021q_rcv(skb, source_port, switch_id);

        /* Try our best with imprecise RX */
        *vid = vlan_tci & VLAN_VID_MASK;
}

static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
                                   struct net_device *netdev)
{
        int source_port = -1, switch_id = -1;
        struct sja1105_meta meta = {0};
        struct ethhdr *hdr;
        bool is_link_local;
        bool is_meta;
        u16 vid;

        hdr = eth_hdr(skb);
        is_link_local = sja1105_is_link_local(skb);
        is_meta = sja1105_is_meta_frame(skb);

        if (sja1105_skb_has_tag_8021q(skb)) {
                /* Normal traffic path. */
                sja1105_vlan_rcv(skb, &source_port, &switch_id, &vid);
        } else if (is_link_local) {
                /* Management traffic path. Switch embeds the switch ID and
                 * port ID into bytes of the destination MAC, courtesy of
                 * the incl_srcpt options.
                 */
                source_port = hdr->h_dest[3];
                switch_id = hdr->h_dest[4];
                /* Clear the DMAC bytes that were mangled by the switch */
                hdr->h_dest[3] = 0;
                hdr->h_dest[4] = 0;
        } else if (is_meta) {
                sja1105_meta_unpack(skb, &meta);
                source_port = meta.source_port;
                switch_id = meta.switch_id;
        } else {
                return NULL;
        }

        if (source_port == -1 || switch_id == -1)
                skb->dev = dsa_find_designated_bridge_port_by_vid(netdev, vid);
        else
                skb->dev = dsa_master_find_slave(netdev, switch_id, source_port);
        if (!skb->dev) {
                netdev_warn(netdev, "Couldn't decode source port\n");
                return NULL;
        }

        if (!is_link_local)
                dsa_default_offload_fwd_mark(skb);

        return sja1105_rcv_meta_state_machine(skb, &meta, is_link_local,
                                              is_meta);
}

static struct sk_buff *sja1110_rcv_meta(struct sk_buff *skb, u16 rx_header)
{
        u8 *buf = dsa_etype_header_pos_rx(skb) + SJA1110_HEADER_LEN;
        int switch_id = SJA1110_RX_HEADER_SWITCH_ID(rx_header);
        int n_ts = SJA1110_RX_HEADER_N_TS(rx_header);
        struct net_device *master = skb->dev;
        struct dsa_port *cpu_dp;
        struct dsa_switch *ds;
        int i;

        cpu_dp = master->dsa_ptr;
        ds = dsa_switch_find(cpu_dp->dst->index, switch_id);
        if (!ds) {
                net_err_ratelimited("%s: cannot find switch id %d\n",
                                    master->name, switch_id);
                return NULL;
        }

        for (i = 0; i <= n_ts; i++) {
                u8 ts_id, source_port, dir;
                u64 tstamp;

                ts_id = buf[0];
                source_port = (buf[1] & GENMASK(7, 4)) >> 4;
                dir = (buf[1] & BIT(3)) >> 3;
                tstamp = be64_to_cpu(*(__be64 *)(buf + 2));

                sja1110_process_meta_tstamp(ds, source_port, ts_id, dir,
                                            tstamp);

                buf += SJA1110_META_TSTAMP_SIZE;
        }

        /* Discard the meta frame, we've consumed the timestamps it contained */
        return NULL;
}

static struct sk_buff *sja1110_rcv_inband_control_extension(struct sk_buff *skb,
                                                            int *source_port,
                                                            int *switch_id,
                                                            bool *host_only)
{
        u16 rx_header;

        if (unlikely(!pskb_may_pull(skb, SJA1110_HEADER_LEN)))
                return NULL;

        /* skb->data points to skb_mac_header(skb) + ETH_HLEN, which is exactly
         * what we need because the caller has checked the EtherType (which is
         * located 2 bytes back) and we just need a pointer to the header that
         * comes afterwards.
         */
        rx_header = ntohs(*(__be16 *)skb->data);

        if (rx_header & SJA1110_RX_HEADER_HOST_ONLY)
                *host_only = true;

        if (rx_header & SJA1110_RX_HEADER_IS_METADATA)
                return sja1110_rcv_meta(skb, rx_header);

        /* Timestamp frame, we have a trailer */
        if (rx_header & SJA1110_RX_HEADER_HAS_TRAILER) {
                int start_of_padding = SJA1110_RX_HEADER_TRAILER_POS(rx_header);
                u8 *rx_trailer = skb_tail_pointer(skb) - SJA1110_RX_TRAILER_LEN;
                u64 *tstamp = &SJA1105_SKB_CB(skb)->tstamp;
                u8 last_byte = rx_trailer[12];

                /* The timestamp is unaligned, so we need to use packing()
                 * to get it
                 */
                packing(rx_trailer, tstamp, 63, 0, 8, UNPACK, 0);

                *source_port = SJA1110_RX_TRAILER_SRC_PORT(last_byte);
                *switch_id = SJA1110_RX_TRAILER_SWITCH_ID(last_byte);

                /* skb->len counts from skb->data, while start_of_padding
                 * counts from the destination MAC address. Right now skb->data
                 * is still as set by the DSA master, so to trim away the
                 * padding and trailer we need to account for the fact that
                 * skb->data points to skb_mac_header(skb) + ETH_HLEN.
                 */
                pskb_trim_rcsum(skb, start_of_padding - ETH_HLEN);
        /* Trap-to-host frame, no timestamp trailer */
        } else {
                *source_port = SJA1110_RX_HEADER_SRC_PORT(rx_header);
                *switch_id = SJA1110_RX_HEADER_SWITCH_ID(rx_header);
        }

        /* Advance skb->data past the DSA header */
        skb_pull_rcsum(skb, SJA1110_HEADER_LEN);

        dsa_strip_etype_header(skb, SJA1110_HEADER_LEN);

        /* With skb->data in its final place, update the MAC header
         * so that eth_hdr() continues to works properly.
         */
        skb_set_mac_header(skb, -ETH_HLEN);

        return skb;
}

static struct sk_buff *sja1110_rcv(struct sk_buff *skb,
                                   struct net_device *netdev)
{
        int source_port = -1, switch_id = -1;
        bool host_only = false;
        u16 vid = 0;

        if (sja1110_skb_has_inband_control_extension(skb)) {
                skb = sja1110_rcv_inband_control_extension(skb, &source_port,
                                                           &switch_id,
                                                           &host_only);
                if (!skb)
                        return NULL;
        }

        /* Packets with in-band control extensions might still have RX VLANs */
        if (likely(sja1105_skb_has_tag_8021q(skb)))
                sja1105_vlan_rcv(skb, &source_port, &switch_id, &vid);

        if (source_port == -1 || switch_id == -1)
                skb->dev = dsa_find_designated_bridge_port_by_vid(netdev, vid);
        else
                skb->dev = dsa_master_find_slave(netdev, switch_id, source_port);
        if (!skb->dev) {
                netdev_warn(netdev, "Couldn't decode source port\n");
                return NULL;
        }

        if (!host_only)
                dsa_default_offload_fwd_mark(skb);

        return skb;
}

static void sja1105_flow_dissect(const struct sk_buff *skb, __be16 *proto,
                                 int *offset)
{
        /* No tag added for management frames, all ok */
        if (unlikely(sja1105_is_link_local(skb)))
                return;

        dsa_tag_generic_flow_dissect(skb, proto, offset);
}

static void sja1110_flow_dissect(const struct sk_buff *skb, __be16 *proto,
                                 int *offset)
{
        /* Management frames have 2 DSA tags on RX, so the needed_headroom we
         * declared is fine for the generic dissector adjustment procedure.
         */
        if (unlikely(sja1105_is_link_local(skb)))
                return dsa_tag_generic_flow_dissect(skb, proto, offset);

        /* For the rest, there is a single DSA tag, the tag_8021q one */
        *offset = VLAN_HLEN;
        *proto = ((__be16 *)skb->data)[(VLAN_HLEN / 2) - 1];
}

static const struct dsa_device_ops sja1105_netdev_ops = {
        .name = "sja1105",
        .proto = DSA_TAG_PROTO_SJA1105,
        .xmit = sja1105_xmit,
        .rcv = sja1105_rcv,
        .needed_headroom = VLAN_HLEN,
        .flow_dissect = sja1105_flow_dissect,
        .promisc_on_master = true,
};

DSA_TAG_DRIVER(sja1105_netdev_ops);
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_SJA1105);

static const struct dsa_device_ops sja1110_netdev_ops = {
        .name = "sja1110",
        .proto = DSA_TAG_PROTO_SJA1110,
        .xmit = sja1110_xmit,
        .rcv = sja1110_rcv,
        .flow_dissect = sja1110_flow_dissect,
        .needed_headroom = SJA1110_HEADER_LEN + VLAN_HLEN,
        .needed_tailroom = SJA1110_RX_TRAILER_LEN + SJA1110_MAX_PADDING_LEN,
};

DSA_TAG_DRIVER(sja1110_netdev_ops);
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_SJA1110);

static struct dsa_tag_driver *sja1105_tag_driver_array[] = {
        &DSA_TAG_DRIVER_NAME(sja1105_netdev_ops),
        &DSA_TAG_DRIVER_NAME(sja1110_netdev_ops),
};

module_dsa_tag_drivers(sja1105_tag_driver_array);

MODULE_LICENSE("GPL v2");