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 "dsa_priv.h" 15 16 #define HELLCREEK_TAG_LEN 1 17 18 static struct sk_buff *hellcreek_xmit(struct sk_buff *skb, 19 struct net_device *dev) 20 { 21 struct dsa_port *dp = dsa_slave_to_port(dev); 22 u8 *tag; 23 24 /* Calculate checksums (if required) before adding the trailer tag to 25 * avoid including it in calculations. That would lead to wrong 26 * checksums after the switch strips the tag. 27 */ 28 if (skb->ip_summed == CHECKSUM_PARTIAL && 29 skb_checksum_help(skb)) 30 return NULL; 31 32 /* Tag encoding */ 33 tag = skb_put(skb, HELLCREEK_TAG_LEN); 34 *tag = BIT(dp->index); 35 36 return skb; 37 } 38 39 static struct sk_buff *hellcreek_rcv(struct sk_buff *skb, 40 struct net_device *dev) 41 { 42 /* Tag decoding */ 43 u8 *tag = skb_tail_pointer(skb) - HELLCREEK_TAG_LEN; 44 unsigned int port = tag[0] & 0x03; 45 46 skb->dev = dsa_master_find_slave(dev, 0, port); 47 if (!skb->dev) { 48 netdev_warn_once(dev, "Failed to get source port: %d\n", port); 49 return NULL; 50 } 51 52 pskb_trim_rcsum(skb, skb->len - HELLCREEK_TAG_LEN); 53 54 dsa_default_offload_fwd_mark(skb); 55 56 return skb; 57 } 58 59 static const struct dsa_device_ops hellcreek_netdev_ops = { 60 .name = "hellcreek", 61 .proto = DSA_TAG_PROTO_HELLCREEK, 62 .xmit = hellcreek_xmit, 63 .rcv = hellcreek_rcv, 64 .needed_tailroom = HELLCREEK_TAG_LEN, 65 }; 66 67 MODULE_LICENSE("Dual MIT/GPL"); 68 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_HELLCREEK); 69 70 module_dsa_tag_driver(hellcreek_netdev_ops); 71