259 lines
7.9 KiB
C
259 lines
7.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Handler for Realtek 8 byte switch tags
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*
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* Copyright (C) 2021 Alvin Šipraga <alsi@bang-olufsen.dk>
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*
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* NOTE: Currently only supports protocol "4" found in the RTL8365MB, hence
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* named tag_rtl8_4.
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*
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* This tag has the following format:
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*
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* 0 7|8 15
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* |-----------------------------------+-----------------------------------|---
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* | (16-bit) | ^
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* | Realtek EtherType [0x8899] | |
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* |-----------------------------------+-----------------------------------| 8
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* | (8-bit) | (8-bit) |
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* | Protocol [0x04] | REASON | b
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* |-----------------------------------+-----------------------------------| y
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* | (1) | (1) | (2) | (1) | (3) | (1) | (1) | (1) | (5) | t
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* | FID_EN | X | FID | PRI_EN | PRI | KEEP | X | LEARN_DIS | X | e
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* |-----------------------------------+-----------------------------------| s
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* | (1) | (15-bit) | |
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* | ALLOW | TX/RX | v
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* |-----------------------------------+-----------------------------------|---
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*
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* With the following field descriptions:
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*
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* field | description
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* ------------+-------------
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* Realtek | 0x8899: indicates that this is a proprietary Realtek tag;
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* EtherType | note that Realtek uses the same EtherType for
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* | other incompatible tag formats (e.g. tag_rtl4_a.c)
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* Protocol | 0x04: indicates that this tag conforms to this format
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* X | reserved
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* ------------+-------------
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* REASON | reason for forwarding packet to CPU
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* | 0: packet was forwarded or flooded to CPU
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* | 80: packet was trapped to CPU
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* FID_EN | 1: packet has an FID
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* | 0: no FID
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* FID | FID of packet (if FID_EN=1)
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* PRI_EN | 1: force priority of packet
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* | 0: don't force priority
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* PRI | priority of packet (if PRI_EN=1)
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* KEEP | preserve packet VLAN tag format
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* LEARN_DIS | don't learn the source MAC address of the packet
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* ALLOW | 1: treat TX/RX field as an allowance port mask, meaning the
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* | packet may only be forwarded to ports specified in the
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* | mask
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* | 0: no allowance port mask, TX/RX field is the forwarding
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* | port mask
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* TX/RX | TX (switch->CPU): port number the packet was received on
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* | RX (CPU->switch): forwarding port mask (if ALLOW=0)
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* | allowance port mask (if ALLOW=1)
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*
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* The tag can be positioned before Ethertype, using tag "rtl8_4":
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*
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* +--------+--------+------------+------+-----
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* | MAC DA | MAC SA | 8 byte tag | Type | ...
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* +--------+--------+------------+------+-----
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*
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* The tag can also appear between the end of the payload and before the CRC,
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* using tag "rtl8_4t":
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*
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* +--------+--------+------+-----+---------+------------+-----+
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* | MAC DA | MAC SA | TYPE | ... | payload | 8-byte tag | CRC |
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* +--------+--------+------+-----+---------+------------+-----+
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*
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* The added bytes after the payload will break most checksums, either in
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* software or hardware. To avoid this issue, if the checksum is still pending,
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* this tagger checksums the packet in software before adding the tag.
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*
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*/
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#include <linux/bitfield.h>
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#include <linux/bits.h>
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#include <linux/etherdevice.h>
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#include "dsa_priv.h"
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/* Protocols supported:
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*
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* 0x04 = RTL8365MB DSA protocol
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*/
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#define RTL8_4_TAG_LEN 8
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#define RTL8_4_PROTOCOL GENMASK(15, 8)
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#define RTL8_4_PROTOCOL_RTL8365MB 0x04
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#define RTL8_4_REASON GENMASK(7, 0)
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#define RTL8_4_REASON_FORWARD 0
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#define RTL8_4_REASON_TRAP 80
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#define RTL8_4_LEARN_DIS BIT(5)
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#define RTL8_4_TX GENMASK(3, 0)
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#define RTL8_4_RX GENMASK(10, 0)
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static void rtl8_4_write_tag(struct sk_buff *skb, struct net_device *dev,
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void *tag)
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{
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struct dsa_port *dp = dsa_slave_to_port(dev);
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__be16 tag16[RTL8_4_TAG_LEN / 2];
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/* Set Realtek EtherType */
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tag16[0] = htons(ETH_P_REALTEK);
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/* Set Protocol; zero REASON */
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tag16[1] = htons(FIELD_PREP(RTL8_4_PROTOCOL, RTL8_4_PROTOCOL_RTL8365MB));
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/* Zero FID_EN, FID, PRI_EN, PRI, KEEP; set LEARN_DIS */
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tag16[2] = htons(FIELD_PREP(RTL8_4_LEARN_DIS, 1));
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/* Zero ALLOW; set RX (CPU->switch) forwarding port mask */
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tag16[3] = htons(FIELD_PREP(RTL8_4_RX, BIT(dp->index)));
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memcpy(tag, tag16, RTL8_4_TAG_LEN);
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}
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static struct sk_buff *rtl8_4_tag_xmit(struct sk_buff *skb,
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struct net_device *dev)
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{
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skb_push(skb, RTL8_4_TAG_LEN);
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dsa_alloc_etype_header(skb, RTL8_4_TAG_LEN);
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rtl8_4_write_tag(skb, dev, dsa_etype_header_pos_tx(skb));
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return skb;
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}
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static struct sk_buff *rtl8_4t_tag_xmit(struct sk_buff *skb,
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struct net_device *dev)
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{
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/* Calculate the checksum here if not done yet as trailing tags will
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* break either software or hardware based checksum
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*/
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if (skb->ip_summed == CHECKSUM_PARTIAL && skb_checksum_help(skb))
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return NULL;
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rtl8_4_write_tag(skb, dev, skb_put(skb, RTL8_4_TAG_LEN));
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return skb;
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}
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static int rtl8_4_read_tag(struct sk_buff *skb, struct net_device *dev,
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void *tag)
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{
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__be16 tag16[RTL8_4_TAG_LEN / 2];
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u16 etype;
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u8 reason;
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u8 proto;
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u8 port;
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memcpy(tag16, tag, RTL8_4_TAG_LEN);
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/* Parse Realtek EtherType */
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etype = ntohs(tag16[0]);
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if (unlikely(etype != ETH_P_REALTEK)) {
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dev_warn_ratelimited(&dev->dev,
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"non-realtek ethertype 0x%04x\n", etype);
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return -EPROTO;
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}
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/* Parse Protocol */
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proto = FIELD_GET(RTL8_4_PROTOCOL, ntohs(tag16[1]));
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if (unlikely(proto != RTL8_4_PROTOCOL_RTL8365MB)) {
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dev_warn_ratelimited(&dev->dev,
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"unknown realtek protocol 0x%02x\n",
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proto);
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return -EPROTO;
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}
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/* Parse REASON */
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reason = FIELD_GET(RTL8_4_REASON, ntohs(tag16[1]));
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/* Parse TX (switch->CPU) */
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port = FIELD_GET(RTL8_4_TX, ntohs(tag16[3]));
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skb->dev = dsa_master_find_slave(dev, 0, port);
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if (!skb->dev) {
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dev_warn_ratelimited(&dev->dev,
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"could not find slave for port %d\n",
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port);
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return -ENOENT;
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}
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if (reason != RTL8_4_REASON_TRAP)
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dsa_default_offload_fwd_mark(skb);
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return 0;
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}
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static struct sk_buff *rtl8_4_tag_rcv(struct sk_buff *skb,
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struct net_device *dev)
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{
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if (unlikely(!pskb_may_pull(skb, RTL8_4_TAG_LEN)))
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return NULL;
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if (unlikely(rtl8_4_read_tag(skb, dev, dsa_etype_header_pos_rx(skb))))
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return NULL;
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/* Remove tag and recalculate checksum */
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skb_pull_rcsum(skb, RTL8_4_TAG_LEN);
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dsa_strip_etype_header(skb, RTL8_4_TAG_LEN);
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return skb;
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}
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static struct sk_buff *rtl8_4t_tag_rcv(struct sk_buff *skb,
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struct net_device *dev)
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{
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if (skb_linearize(skb))
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return NULL;
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if (unlikely(rtl8_4_read_tag(skb, dev, skb_tail_pointer(skb) - RTL8_4_TAG_LEN)))
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return NULL;
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if (pskb_trim_rcsum(skb, skb->len - RTL8_4_TAG_LEN))
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return NULL;
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return skb;
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}
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/* Ethertype version */
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static const struct dsa_device_ops rtl8_4_netdev_ops = {
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.name = "rtl8_4",
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.proto = DSA_TAG_PROTO_RTL8_4,
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.xmit = rtl8_4_tag_xmit,
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.rcv = rtl8_4_tag_rcv,
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.needed_headroom = RTL8_4_TAG_LEN,
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};
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DSA_TAG_DRIVER(rtl8_4_netdev_ops);
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MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_RTL8_4);
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/* Tail version */
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static const struct dsa_device_ops rtl8_4t_netdev_ops = {
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.name = "rtl8_4t",
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.proto = DSA_TAG_PROTO_RTL8_4T,
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.xmit = rtl8_4t_tag_xmit,
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.rcv = rtl8_4t_tag_rcv,
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.needed_tailroom = RTL8_4_TAG_LEN,
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};
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DSA_TAG_DRIVER(rtl8_4t_netdev_ops);
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MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_RTL8_4T);
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static struct dsa_tag_driver *dsa_tag_drivers[] = {
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&DSA_TAG_DRIVER_NAME(rtl8_4_netdev_ops),
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&DSA_TAG_DRIVER_NAME(rtl8_4t_netdev_ops),
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};
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module_dsa_tag_drivers(dsa_tag_drivers);
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MODULE_LICENSE("GPL");
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