1 /* 2 * net/dsa/tag_ksz.c - Microchip KSZ Switch tag format handling 3 * Copyright (c) 2017 Microchip Technology 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation; either version 2 of the License, or 8 * (at your option) any later version. 9 */ 10 11 #include <linux/etherdevice.h> 12 #include <linux/list.h> 13 #include <linux/slab.h> 14 #include <net/dsa.h> 15 #include "dsa_priv.h" 16 17 /* For Ingress (Host -> KSZ), 2 bytes are added before FCS. 18 * --------------------------------------------------------------------------- 19 * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|tag0(1byte)|tag1(1byte)|FCS(4bytes) 20 * --------------------------------------------------------------------------- 21 * tag0 : Prioritization (not used now) 22 * tag1 : each bit represents port (eg, 0x01=port1, 0x02=port2, 0x10=port5) 23 * 24 * For Egress (KSZ -> Host), 1 byte is added before FCS. 25 * --------------------------------------------------------------------------- 26 * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|tag0(1byte)|FCS(4bytes) 27 * --------------------------------------------------------------------------- 28 * tag0 : zero-based value represents port 29 * (eg, 0x00=port1, 0x02=port3, 0x06=port7) 30 */ 31 32 #define KSZ_INGRESS_TAG_LEN 2 33 #define KSZ_EGRESS_TAG_LEN 1 34 35 static struct sk_buff *ksz_xmit(struct sk_buff *skb, struct net_device *dev) 36 { 37 struct dsa_port *dp = dsa_slave_to_port(dev); 38 struct sk_buff *nskb; 39 int padlen; 40 u8 *tag; 41 42 padlen = (skb->len >= ETH_ZLEN) ? 0 : ETH_ZLEN - skb->len; 43 44 if (skb_tailroom(skb) >= padlen + KSZ_INGRESS_TAG_LEN) { 45 /* Let dsa_slave_xmit() free skb */ 46 if (__skb_put_padto(skb, skb->len + padlen, false)) 47 return NULL; 48 49 nskb = skb; 50 } else { 51 nskb = alloc_skb(NET_IP_ALIGN + skb->len + 52 padlen + KSZ_INGRESS_TAG_LEN, GFP_ATOMIC); 53 if (!nskb) 54 return NULL; 55 skb_reserve(nskb, NET_IP_ALIGN); 56 57 skb_reset_mac_header(nskb); 58 skb_set_network_header(nskb, 59 skb_network_header(skb) - skb->head); 60 skb_set_transport_header(nskb, 61 skb_transport_header(skb) - skb->head); 62 skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len)); 63 64 /* Let skb_put_padto() free nskb, and let dsa_slave_xmit() free 65 * skb 66 */ 67 if (skb_put_padto(nskb, nskb->len + padlen)) 68 return NULL; 69 70 consume_skb(skb); 71 } 72 73 tag = skb_put(nskb, KSZ_INGRESS_TAG_LEN); 74 tag[0] = 0; 75 tag[1] = 1 << dp->index; /* destination port */ 76 77 return nskb; 78 } 79 80 static struct sk_buff *ksz_rcv(struct sk_buff *skb, struct net_device *dev, 81 struct packet_type *pt) 82 { 83 u8 *tag; 84 int source_port; 85 86 tag = skb_tail_pointer(skb) - KSZ_EGRESS_TAG_LEN; 87 88 source_port = tag[0] & 7; 89 90 skb->dev = dsa_master_find_slave(dev, 0, source_port); 91 if (!skb->dev) 92 return NULL; 93 94 pskb_trim_rcsum(skb, skb->len - KSZ_EGRESS_TAG_LEN); 95 96 return skb; 97 } 98 99 const struct dsa_device_ops ksz_netdev_ops = { 100 .xmit = ksz_xmit, 101 .rcv = ksz_rcv, 102 }; 103