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4e50025129
Some really really weird switches just couldn't decide whether to use a normal or a tail tagger, so they just did both. This creates problems for DSA, because we only have the concept of an 'overhead' which can be applied to the headroom or to the tailroom of the skb (like for example during the central TX reallocation procedure), depending on the value of bool tail_tag, but not to both. We need to generalize DSA to cater for these odd switches by transforming the 'overhead / tail_tag' pair into 'needed_headroom / needed_tailroom'. The DSA master's MTU is increased to account for both. The flow dissector code is modified such that it only calls the DSA adjustment callback if the tagger has a non-zero header length. Taggers are trivially modified to declare either needed_headroom or needed_tailroom, based on the tail_tag value that they currently declare. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
132 lines
3.3 KiB
C
132 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Handler for Realtek 4 byte DSA switch tags
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* Currently only supports protocol "A" found in RTL8366RB
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* Copyright (c) 2020 Linus Walleij <linus.walleij@linaro.org>
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*
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* This "proprietary tag" header looks like so:
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*
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* -------------------------------------------------
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* | MAC DA | MAC SA | 0x8899 | 2 bytes tag | Type |
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* -------------------------------------------------
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*
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* The 2 bytes tag form a 16 bit big endian word. The exact
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* meaning has been guessed from packet dumps from ingress
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* frames.
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*/
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#include <linux/etherdevice.h>
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#include <linux/bits.h>
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#include "dsa_priv.h"
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#define RTL4_A_HDR_LEN 4
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#define RTL4_A_ETHERTYPE 0x8899
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#define RTL4_A_PROTOCOL_SHIFT 12
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/*
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* 0x1 = Realtek Remote Control protocol (RRCP)
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* 0x2/0x3 seems to be used for loopback testing
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* 0x9 = RTL8306 DSA protocol
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* 0xa = RTL8366RB DSA protocol
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*/
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#define RTL4_A_PROTOCOL_RTL8366RB 0xa
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static struct sk_buff *rtl4a_tag_xmit(struct sk_buff *skb,
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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 *p;
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u8 *tag;
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u16 out;
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/* Pad out to at least 60 bytes */
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if (unlikely(__skb_put_padto(skb, ETH_ZLEN, false)))
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return NULL;
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netdev_dbg(dev, "add realtek tag to package to port %d\n",
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dp->index);
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skb_push(skb, RTL4_A_HDR_LEN);
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memmove(skb->data, skb->data + RTL4_A_HDR_LEN, 2 * ETH_ALEN);
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tag = skb->data + 2 * ETH_ALEN;
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/* Set Ethertype */
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p = (__be16 *)tag;
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*p = htons(RTL4_A_ETHERTYPE);
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out = (RTL4_A_PROTOCOL_RTL8366RB << 12) | (2 << 8);
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/* The lower bits is the port number */
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out |= (u8)dp->index;
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p = (__be16 *)(tag + 2);
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*p = htons(out);
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return skb;
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}
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static struct sk_buff *rtl4a_tag_rcv(struct sk_buff *skb,
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struct net_device *dev,
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struct packet_type *pt)
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{
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u16 protport;
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__be16 *p;
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u16 etype;
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u8 *tag;
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u8 prot;
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u8 port;
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if (unlikely(!pskb_may_pull(skb, RTL4_A_HDR_LEN)))
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return NULL;
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/* The RTL4 header has its own custom Ethertype 0x8899 and that
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* starts right at the beginning of the packet, after the src
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* ethernet addr. Apparently skb->data always points 2 bytes in,
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* behind the Ethertype.
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*/
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tag = skb->data - 2;
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p = (__be16 *)tag;
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etype = ntohs(*p);
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if (etype != RTL4_A_ETHERTYPE) {
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/* Not custom, just pass through */
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netdev_dbg(dev, "non-realtek ethertype 0x%04x\n", etype);
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return skb;
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}
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p = (__be16 *)(tag + 2);
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protport = ntohs(*p);
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/* The 4 upper bits are the protocol */
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prot = (protport >> RTL4_A_PROTOCOL_SHIFT) & 0x0f;
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if (prot != RTL4_A_PROTOCOL_RTL8366RB) {
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netdev_err(dev, "unknown realtek protocol 0x%01x\n", prot);
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return NULL;
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}
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port = protport & 0xff;
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skb->dev = dsa_master_find_slave(dev, 0, port);
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if (!skb->dev) {
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netdev_dbg(dev, "could not find slave for port %d\n", port);
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return NULL;
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}
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/* Remove RTL4 tag and recalculate checksum */
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skb_pull_rcsum(skb, RTL4_A_HDR_LEN);
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/* Move ethernet DA and SA in front of the data */
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memmove(skb->data - ETH_HLEN,
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skb->data - ETH_HLEN - RTL4_A_HDR_LEN,
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2 * ETH_ALEN);
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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 rtl4a_netdev_ops = {
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.name = "rtl4a",
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.proto = DSA_TAG_PROTO_RTL4_A,
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.xmit = rtl4a_tag_xmit,
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.rcv = rtl4a_tag_rcv,
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.needed_headroom = RTL4_A_HDR_LEN,
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};
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module_dsa_tag_driver(rtl4a_netdev_ops);
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_RTL4_A);
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