// SPDX-License-Identifier: GPL-2.0+
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/*
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* net/dsa/tag_edsa.c - 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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#define EDSA_HLEN 8
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#define FRAME_TYPE_TO_CPU 0x00
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#define FRAME_TYPE_FORWARD 0x03
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#define TO_CPU_CODE_MGMT_TRAP 0x00
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#define TO_CPU_CODE_FRAME2REG 0x01
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#define TO_CPU_CODE_IGMP_MLD_TRAP 0x02
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#define TO_CPU_CODE_POLICY_TRAP 0x03
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#define TO_CPU_CODE_ARP_MIRROR 0x04
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#define TO_CPU_CODE_POLICY_MIRROR 0x05
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static struct sk_buff *edsa_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 *edsa_header;
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/*
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* Convert the outermost 802.1q tag to a DSA tag and prepend
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* a DSA ethertype field is the packet is tagged, or insert
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* a DSA ethertype plus DSA tag between the addresses and the
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* current ethertype field if the packet is untagged.
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*/
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if (skb->protocol == htons(ETH_P_8021Q)) {
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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 tagged FROM_CPU DSA tag from 802.1q tag.
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*/
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edsa_header = skb->data + 2 * ETH_ALEN;
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edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
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edsa_header[1] = ETH_P_EDSA & 0xff;
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edsa_header[2] = 0x00;
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edsa_header[3] = 0x00;
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edsa_header[4] = 0x60 | dp->ds->index;
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edsa_header[5] = dp->index << 3;
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/*
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* Move CFI field from byte 6 to byte 5.
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*/
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if (edsa_header[6] & 0x10) {
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edsa_header[5] |= 0x01;
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edsa_header[6] &= ~0x10;
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}
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} else {
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skb_push(skb, EDSA_HLEN);
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memmove(skb->data, skb->data + EDSA_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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edsa_header = skb->data + 2 * ETH_ALEN;
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edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
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edsa_header[1] = ETH_P_EDSA & 0xff;
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edsa_header[2] = 0x00;
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edsa_header[3] = 0x00;
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edsa_header[4] = 0x40 | dp->ds->index;
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edsa_header[5] = dp->index << 3;
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edsa_header[6] = 0x00;
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edsa_header[7] = 0x00;
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}
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return skb;
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}
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static struct sk_buff *edsa_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 *edsa_header;
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int frame_type;
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int code;
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int source_device;
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int source_port;
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if (unlikely(!pskb_may_pull(skb, EDSA_HLEN)))
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return NULL;
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/*
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* Skip the two null bytes after the ethertype.
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*/
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edsa_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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frame_type = edsa_header[0] >> 6;
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switch (frame_type) {
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case FRAME_TYPE_TO_CPU:
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code = (edsa_header[1] & 0x6) | ((edsa_header[2] >> 4) & 1);
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/*
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* Mark the frame to never egress on any port of the same switch
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* unless it's a trapped IGMP/MLD packet, in which case the
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* bridge might want to forward it.
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*/
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if (code != TO_CPU_CODE_IGMP_MLD_TRAP)
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skb->offload_fwd_mark = 1;
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break;
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case FRAME_TYPE_FORWARD:
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skb->offload_fwd_mark = 1;
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break;
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default:
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return NULL;
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}
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/*
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* Determine source device and port.
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*/
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source_device = edsa_header[0] & 0x1f;
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source_port = (edsa_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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* If the 'tagged' bit is set, convert the DSA tag to a 802.1q
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* tag and delete the ethertype part. If the 'tagged' bit is
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* clear, delete the ethertype and the DSA tag parts.
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*/
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if (edsa_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] = edsa_header[2] & ~0x10;
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new_header[3] = edsa_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 (edsa_header[1] & 0x01)
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new_header[2] |= 0x10;
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skb_pull_rcsum(skb, DSA_HLEN);
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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(edsa_header + 2, 2, 0));
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skb->csum = c;
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}
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memcpy(edsa_header, new_header, 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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} 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, EDSA_HLEN);
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memmove(skb->data - ETH_HLEN,
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skb->data - ETH_HLEN - EDSA_HLEN,
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2 * ETH_ALEN);
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}
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return skb;
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}
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static const struct dsa_device_ops edsa_netdev_ops = {
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.name = "edsa",
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.proto = DSA_TAG_PROTO_EDSA,
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.xmit = edsa_xmit,
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.rcv = edsa_rcv,
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.overhead = EDSA_HLEN,
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};
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_EDSA);
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module_dsa_tag_driver(edsa_netdev_ops);
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