| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Handler for Realtek 4 byte DSA switch tags |
| * Currently only supports protocol "A" found in RTL8366RB |
| * Copyright (c) 2020 Linus Walleij <linus.walleij@linaro.org> |
| * |
| * This "proprietary tag" header looks like so: |
| * |
| * ------------------------------------------------- |
| * | MAC DA | MAC SA | 0x8899 | 2 bytes tag | Type | |
| * ------------------------------------------------- |
| * |
| * The 2 bytes tag form a 16 bit big endian word. The exact |
| * meaning has been guessed from packet dumps from ingress |
| * frames. |
| */ |
| |
| #include <linux/etherdevice.h> |
| #include <linux/bits.h> |
| |
| #include "dsa_priv.h" |
| |
| #define RTL4_A_HDR_LEN 4 |
| #define RTL4_A_ETHERTYPE 0x8899 |
| #define RTL4_A_PROTOCOL_SHIFT 12 |
| /* |
| * 0x1 = Realtek Remote Control protocol (RRCP) |
| * 0x2/0x3 seems to be used for loopback testing |
| * 0x9 = RTL8306 DSA protocol |
| * 0xa = RTL8366RB DSA protocol |
| */ |
| #define RTL4_A_PROTOCOL_RTL8366RB 0xa |
| |
| static struct sk_buff *rtl4a_tag_xmit(struct sk_buff *skb, |
| struct net_device *dev) |
| { |
| struct dsa_port *dp = dsa_slave_to_port(dev); |
| __be16 *p; |
| u8 *tag; |
| u16 out; |
| |
| /* Pad out to at least 60 bytes */ |
| if (unlikely(__skb_put_padto(skb, ETH_ZLEN, false))) |
| return NULL; |
| |
| netdev_dbg(dev, "add realtek tag to package to port %d\n", |
| dp->index); |
| skb_push(skb, RTL4_A_HDR_LEN); |
| |
| memmove(skb->data, skb->data + RTL4_A_HDR_LEN, 2 * ETH_ALEN); |
| tag = skb->data + 2 * ETH_ALEN; |
| |
| /* Set Ethertype */ |
| p = (__be16 *)tag; |
| *p = htons(RTL4_A_ETHERTYPE); |
| |
| out = (RTL4_A_PROTOCOL_RTL8366RB << 12) | (2 << 8); |
| /* The lower bits is the port number */ |
| out |= (u8)dp->index; |
| p = (__be16 *)(tag + 2); |
| *p = htons(out); |
| |
| return skb; |
| } |
| |
| static struct sk_buff *rtl4a_tag_rcv(struct sk_buff *skb, |
| struct net_device *dev, |
| struct packet_type *pt) |
| { |
| u16 protport; |
| __be16 *p; |
| u16 etype; |
| u8 *tag; |
| u8 prot; |
| u8 port; |
| |
| if (unlikely(!pskb_may_pull(skb, RTL4_A_HDR_LEN))) |
| return NULL; |
| |
| /* The RTL4 header has its own custom Ethertype 0x8899 and that |
| * starts right at the beginning of the packet, after the src |
| * ethernet addr. Apparently skb->data always points 2 bytes in, |
| * behind the Ethertype. |
| */ |
| tag = skb->data - 2; |
| p = (__be16 *)tag; |
| etype = ntohs(*p); |
| if (etype != RTL4_A_ETHERTYPE) { |
| /* Not custom, just pass through */ |
| netdev_dbg(dev, "non-realtek ethertype 0x%04x\n", etype); |
| return skb; |
| } |
| p = (__be16 *)(tag + 2); |
| protport = ntohs(*p); |
| /* The 4 upper bits are the protocol */ |
| prot = (protport >> RTL4_A_PROTOCOL_SHIFT) & 0x0f; |
| if (prot != RTL4_A_PROTOCOL_RTL8366RB) { |
| netdev_err(dev, "unknown realtek protocol 0x%01x\n", prot); |
| return NULL; |
| } |
| port = protport & 0xff; |
| |
| skb->dev = dsa_master_find_slave(dev, 0, port); |
| if (!skb->dev) { |
| netdev_dbg(dev, "could not find slave for port %d\n", port); |
| return NULL; |
| } |
| |
| /* Remove RTL4 tag and recalculate checksum */ |
| skb_pull_rcsum(skb, RTL4_A_HDR_LEN); |
| |
| /* Move ethernet DA and SA in front of the data */ |
| memmove(skb->data - ETH_HLEN, |
| skb->data - ETH_HLEN - RTL4_A_HDR_LEN, |
| 2 * ETH_ALEN); |
| |
| skb->offload_fwd_mark = 1; |
| |
| return skb; |
| } |
| |
| static const struct dsa_device_ops rtl4a_netdev_ops = { |
| .name = "rtl4a", |
| .proto = DSA_TAG_PROTO_RTL4_A, |
| .xmit = rtl4a_tag_xmit, |
| .rcv = rtl4a_tag_rcv, |
| .needed_headroom = RTL4_A_HDR_LEN, |
| }; |
| module_dsa_tag_driver(rtl4a_netdev_ops); |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_RTL4_A); |