// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2017 Pengutronix, Juergen Borleis <jbe@pengutronix.de>
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*/
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#include <linux/dsa/lan9303.h>
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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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/* To define the outgoing port and to discover the incoming port a regular
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* VLAN tag is used by the LAN9303. But its VID meaning is 'special':
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*
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* Dest MAC Src MAC TAG Type
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* ...| 1 2 3 4 5 6 | 1 2 3 4 5 6 | 1 2 3 4 | 1 2 |...
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* |<------->|
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* TAG:
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* |<------------->|
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* | 1 2 | 3 4 |
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* TPID VID
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* 0x8100
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*
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* VID bit 3 indicates a request for an ALR lookup.
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*
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* If VID bit 3 is zero, then bits 0 and 1 specify the destination port
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* (0, 1, 2) or broadcast (3) or the source port (1, 2).
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*
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* VID bit 4 is used to specify if the STP port state should be overridden.
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* Required when no forwarding between the external ports should happen.
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*/
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#define LAN9303_TAG_LEN 4
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# define LAN9303_TAG_TX_USE_ALR BIT(3)
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# define LAN9303_TAG_TX_STP_OVERRIDE BIT(4)
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# define LAN9303_TAG_RX_IGMP BIT(3)
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# define LAN9303_TAG_RX_STP BIT(4)
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# define LAN9303_TAG_RX_TRAPPED_TO_CPU (LAN9303_TAG_RX_IGMP | \
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LAN9303_TAG_RX_STP)
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/* Decide whether to transmit using ALR lookup, or transmit directly to
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* port using tag. ALR learning is performed only when using ALR lookup.
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* If the two external ports are bridged and the frame is unicast,
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* then use ALR lookup to allow ALR learning on CPU port.
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* Otherwise transmit directly to port with STP state override.
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* See also: lan9303_separate_ports() and lan9303.pdf 6.4.10.1
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*/
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static int lan9303_xmit_use_arl(struct dsa_port *dp, u8 *dest_addr)
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{
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struct lan9303 *chip = dp->ds->priv;
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return chip->is_bridged && !is_multicast_ether_addr(dest_addr);
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}
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static struct sk_buff *lan9303_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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__be16 *lan9303_tag;
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u16 tag;
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/* provide 'LAN9303_TAG_LEN' bytes additional space */
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skb_push(skb, LAN9303_TAG_LEN);
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/* make room between MACs and Ether-Type */
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memmove(skb->data, skb->data + LAN9303_TAG_LEN, 2 * ETH_ALEN);
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lan9303_tag = (__be16 *)(skb->data + 2 * ETH_ALEN);
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tag = lan9303_xmit_use_arl(dp, skb->data) ?
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LAN9303_TAG_TX_USE_ALR :
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dp->index | LAN9303_TAG_TX_STP_OVERRIDE;
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lan9303_tag[0] = htons(ETH_P_8021Q);
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lan9303_tag[1] = htons(tag);
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return skb;
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}
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static struct sk_buff *lan9303_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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__be16 *lan9303_tag;
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u16 lan9303_tag1;
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unsigned int source_port;
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if (unlikely(!pskb_may_pull(skb, LAN9303_TAG_LEN))) {
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dev_warn_ratelimited(&dev->dev,
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"Dropping packet, cannot pull\n");
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return NULL;
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}
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/* '->data' points into the middle of our special VLAN tag information:
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*
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* ~ MAC src | 0x81 | 0x00 | 0xyy | 0xzz | ether type
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* ^
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* ->data
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*/
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lan9303_tag = (__be16 *)(skb->data - 2);
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if (lan9303_tag[0] != htons(ETH_P_8021Q)) {
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dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid VLAN marker\n");
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return NULL;
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}
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lan9303_tag1 = ntohs(lan9303_tag[1]);
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source_port = lan9303_tag1 & 0x3;
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skb->dev = dsa_master_find_slave(dev, 0, source_port);
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if (!skb->dev) {
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dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid source port\n");
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return NULL;
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}
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/* remove the special VLAN tag between the MAC addresses
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* and the current ethertype field.
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*/
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skb_pull_rcsum(skb, 2 + 2);
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memmove(skb->data - ETH_HLEN, skb->data - (ETH_HLEN + LAN9303_TAG_LEN),
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2 * ETH_ALEN);
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skb->offload_fwd_mark = !(lan9303_tag1 & LAN9303_TAG_RX_TRAPPED_TO_CPU);
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return skb;
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}
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static const struct dsa_device_ops lan9303_netdev_ops = {
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.name = "lan9303",
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.proto = DSA_TAG_PROTO_LAN9303,
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.xmit = lan9303_xmit,
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.rcv = lan9303_rcv,
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.overhead = LAN9303_TAG_LEN,
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};
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_LAN9303);
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module_dsa_tag_driver(lan9303_netdev_ops);
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