// SPDX-License-Identifier: GPL-2.0+
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/*
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* net/dsa/tag_dsa.c - (Non-ethertype) DSA tagging
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* Copyright (c) 2008-2009 Marvell Semiconductor
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*/
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#include <linux/etherdevice.h>
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#include <linux/list.h>
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#include <linux/slab.h>
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#include "dsa_priv.h"
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#define DSA_HLEN 4
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static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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struct dsa_port *dp = dsa_slave_to_port(dev);
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u8 *dsa_header;
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/*
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* Convert the outermost 802.1q tag to a DSA tag for tagged
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* packets, or insert a DSA tag between the addresses and
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* the ethertype field for untagged packets.
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*/
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if (skb->protocol == htons(ETH_P_8021Q)) {
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/*
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* Construct tagged FROM_CPU DSA tag from 802.1q tag.
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*/
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dsa_header = skb->data + 2 * ETH_ALEN;
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dsa_header[0] = 0x60 | dp->ds->index;
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dsa_header[1] = dp->index << 3;
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/*
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* Move CFI field from byte 2 to byte 1.
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*/
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if (dsa_header[2] & 0x10) {
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dsa_header[1] |= 0x01;
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dsa_header[2] &= ~0x10;
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}
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} else {
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skb_push(skb, DSA_HLEN);
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memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
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/*
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* Construct untagged FROM_CPU DSA tag.
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*/
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dsa_header = skb->data + 2 * ETH_ALEN;
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dsa_header[0] = 0x40 | dp->ds->index;
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dsa_header[1] = dp->index << 3;
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dsa_header[2] = 0x00;
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dsa_header[3] = 0x00;
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}
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return skb;
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}
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static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev,
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struct packet_type *pt)
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{
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u8 *dsa_header;
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int source_device;
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int source_port;
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if (unlikely(!pskb_may_pull(skb, DSA_HLEN)))
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return NULL;
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/*
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* The ethertype field is part of the DSA header.
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*/
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dsa_header = skb->data - 2;
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/*
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* Check that frame type is either TO_CPU or FORWARD.
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*/
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if ((dsa_header[0] & 0xc0) != 0x00 && (dsa_header[0] & 0xc0) != 0xc0)
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return NULL;
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/*
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* Determine source device and port.
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*/
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source_device = dsa_header[0] & 0x1f;
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source_port = (dsa_header[1] >> 3) & 0x1f;
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skb->dev = dsa_master_find_slave(dev, source_device, source_port);
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if (!skb->dev)
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return NULL;
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/*
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* Convert the DSA header to an 802.1q header if the 'tagged'
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* bit in the DSA header is set. If the 'tagged' bit is clear,
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* delete the DSA header entirely.
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*/
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if (dsa_header[0] & 0x20) {
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u8 new_header[4];
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/*
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* Insert 802.1q ethertype and copy the VLAN-related
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* fields, but clear the bit that will hold CFI (since
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* DSA uses that bit location for another purpose).
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*/
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new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
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new_header[1] = ETH_P_8021Q & 0xff;
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new_header[2] = dsa_header[2] & ~0x10;
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new_header[3] = dsa_header[3];
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/*
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* Move CFI bit from its place in the DSA header to
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* its 802.1q-designated place.
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*/
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if (dsa_header[1] & 0x01)
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new_header[2] |= 0x10;
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/*
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* Update packet checksum if skb is CHECKSUM_COMPLETE.
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*/
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if (skb->ip_summed == CHECKSUM_COMPLETE) {
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__wsum c = skb->csum;
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c = csum_add(c, csum_partial(new_header + 2, 2, 0));
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c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0));
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skb->csum = c;
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}
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memcpy(dsa_header, new_header, DSA_HLEN);
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} else {
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/*
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* Remove DSA tag and update checksum.
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*/
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skb_pull_rcsum(skb, DSA_HLEN);
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memmove(skb->data - ETH_HLEN,
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skb->data - ETH_HLEN - DSA_HLEN,
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2 * ETH_ALEN);
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}
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skb->offload_fwd_mark = 1;
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return skb;
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}
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static const struct dsa_device_ops dsa_netdev_ops = {
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.name = "dsa",
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.proto = DSA_TAG_PROTO_DSA,
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.xmit = dsa_xmit,
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.rcv = dsa_rcv,
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.overhead = DSA_HLEN,
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};
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_DSA);
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module_dsa_tag_driver(dsa_netdev_ops);
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