// SPDX-License-Identifier: GPL-2.0+
/*
 * XRS700x tag format handling
 * Copyright (c) 2008-2009 Marvell Semiconductor
 * Copyright (c) 2020 NovaTech LLC
 */

#include <linux/bitops.h>

#include "tag.h"

#define XRS700X_NAME "xrs700x"

static struct sk_buff *xrs700x_xmit(struct sk_buff *skb, struct net_device *dev)
{
        u8 *trailer;

        trailer = skb_put(skb, 1);
        trailer[0] = dsa_xmit_port_mask(skb, dev);

        return skb;
}

static struct sk_buff *xrs700x_rcv(struct sk_buff *skb, struct net_device *dev)
{
        int source_port;
        u8 *trailer;

        trailer = skb_tail_pointer(skb) - 1;

        source_port = ffs((int)trailer[0]) - 1;

        if (source_port < 0)
                return NULL;

        skb->dev = dsa_conduit_find_user(dev, 0, source_port);
        if (!skb->dev)
                return NULL;

        if (pskb_trim_rcsum(skb, skb->len - 1))
                return NULL;

        /* Frame is forwarded by hardware, don't forward in software. */
        dsa_default_offload_fwd_mark(skb);

        return skb;
}

static const struct dsa_device_ops xrs700x_netdev_ops = {
        .name   = XRS700X_NAME,
        .proto  = DSA_TAG_PROTO_XRS700X,
        .xmit   = xrs700x_xmit,
        .rcv    = xrs700x_rcv,
        .needed_tailroom = 1,
};

MODULE_DESCRIPTION("DSA tag driver for XRS700x switches");
MODULE_LICENSE("GPL");
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_XRS700X, XRS700X_NAME);

module_dsa_tag_driver(xrs700x_netdev_ops);