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
ksz_xmit(struct sk_buff * skb,struct net_device * dev)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
ksz_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt)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
