1 // SPDX-License-Identifier: (GPL-2.0 OR MIT) 2 /* 3 * net/dsa/tag_hellcreek.c - Hirschmann Hellcreek switch tag format handling 4 * 5 * Copyright (C) 2019,2020 Linutronix GmbH 6 * Author Kurt Kanzenbach <kurt@linutronix.de> 7 * 8 * Based on tag_ksz.c. 9 */ 10 11 #include <linux/skbuff.h> 12 #include <net/dsa.h> 13 14 #include "tag.h" 15 16 #define HELLCREEK_NAME "hellcreek" 17 18 #define HELLCREEK_TAG_LEN 1 19 20 static struct sk_buff *hellcreek_xmit(struct sk_buff *skb, 21 struct net_device *dev) 22 { 23 u8 *tag; 24 25 /* Calculate checksums (if required) before adding the trailer tag to 26 * avoid including it in calculations. That would lead to wrong 27 * checksums after the switch strips the tag. 28 */ 29 if (skb->ip_summed == CHECKSUM_PARTIAL && 30 skb_checksum_help(skb)) 31 return NULL; 32 33 /* Tag encoding */ 34 tag = skb_put(skb, HELLCREEK_TAG_LEN); 35 *tag = dsa_xmit_port_mask(skb, dev); 36 37 return skb; 38 } 39 40 static struct sk_buff *hellcreek_rcv(struct sk_buff *skb, 41 struct net_device *dev) 42 { 43 /* Tag decoding */ 44 u8 *tag = skb_tail_pointer(skb) - HELLCREEK_TAG_LEN; 45 unsigned int port = tag[0] & 0x03; 46 47 skb->dev = dsa_conduit_find_user(dev, 0, port); 48 if (!skb->dev) { 49 netdev_warn_once(dev, "Failed to get source port: %d\n", port); 50 return NULL; 51 } 52 53 if (pskb_trim_rcsum(skb, skb->len - HELLCREEK_TAG_LEN)) 54 return NULL; 55 56 dsa_default_offload_fwd_mark(skb); 57 58 return skb; 59 } 60 61 static const struct dsa_device_ops hellcreek_netdev_ops = { 62 .name = HELLCREEK_NAME, 63 .proto = DSA_TAG_PROTO_HELLCREEK, 64 .xmit = hellcreek_xmit, 65 .rcv = hellcreek_rcv, 66 .needed_tailroom = HELLCREEK_TAG_LEN, 67 }; 68 69 MODULE_DESCRIPTION("DSA tag driver for Hirschmann Hellcreek TSN switches"); 70 MODULE_LICENSE("Dual MIT/GPL"); 71 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_HELLCREEK, HELLCREEK_NAME); 72 73 module_dsa_tag_driver(hellcreek_netdev_ops); 74