1 /*
2  * Copyright (c) 2015, The Linux Foundation. All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 and
6  * only version 2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11  * GNU General Public License for more details.
12  */
13 
14 #include <linux/etherdevice.h>
15 
16 #include "dsa_priv.h"
17 
18 #define QCA_HDR_LEN	2
19 #define QCA_HDR_VERSION	0x2
20 
21 #define QCA_HDR_RECV_VERSION_MASK	GENMASK(15, 14)
22 #define QCA_HDR_RECV_VERSION_S		14
23 #define QCA_HDR_RECV_PRIORITY_MASK	GENMASK(13, 11)
24 #define QCA_HDR_RECV_PRIORITY_S		11
25 #define QCA_HDR_RECV_TYPE_MASK		GENMASK(10, 6)
26 #define QCA_HDR_RECV_TYPE_S		6
27 #define QCA_HDR_RECV_FRAME_IS_TAGGED	BIT(3)
28 #define QCA_HDR_RECV_SOURCE_PORT_MASK	GENMASK(2, 0)
29 
30 #define QCA_HDR_XMIT_VERSION_MASK	GENMASK(15, 14)
31 #define QCA_HDR_XMIT_VERSION_S		14
32 #define QCA_HDR_XMIT_PRIORITY_MASK	GENMASK(13, 11)
33 #define QCA_HDR_XMIT_PRIORITY_S		11
34 #define QCA_HDR_XMIT_CONTROL_MASK	GENMASK(10, 8)
35 #define QCA_HDR_XMIT_CONTROL_S		8
36 #define QCA_HDR_XMIT_FROM_CPU		BIT(7)
37 #define QCA_HDR_XMIT_DP_BIT_MASK	GENMASK(6, 0)
38 
qca_tag_xmit(struct sk_buff * skb,struct net_device * dev)39 static struct sk_buff *qca_tag_xmit(struct sk_buff *skb, struct net_device *dev)
40 {
41 	struct dsa_port *dp = dsa_slave_to_port(dev);
42 	u16 *phdr, hdr;
43 
44 	dev->stats.tx_packets++;
45 	dev->stats.tx_bytes += skb->len;
46 
47 	if (skb_cow_head(skb, 0) < 0)
48 		return NULL;
49 
50 	skb_push(skb, QCA_HDR_LEN);
51 
52 	memmove(skb->data, skb->data + QCA_HDR_LEN, 2 * ETH_ALEN);
53 	phdr = (u16 *)(skb->data + 2 * ETH_ALEN);
54 
55 	/* Set the version field, and set destination port information */
56 	hdr = QCA_HDR_VERSION << QCA_HDR_XMIT_VERSION_S |
57 		QCA_HDR_XMIT_FROM_CPU | BIT(dp->index);
58 
59 	*phdr = htons(hdr);
60 
61 	return skb;
62 }
63 
qca_tag_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt)64 static struct sk_buff *qca_tag_rcv(struct sk_buff *skb, struct net_device *dev,
65 				   struct packet_type *pt)
66 {
67 	u8 ver;
68 	int port;
69 	__be16 *phdr, hdr;
70 
71 	if (unlikely(!pskb_may_pull(skb, QCA_HDR_LEN)))
72 		return NULL;
73 
74 	/* The QCA header is added by the switch between src addr and Ethertype
75 	 * At this point, skb->data points to ethertype so header should be
76 	 * right before
77 	 */
78 	phdr = (__be16 *)(skb->data - 2);
79 	hdr = ntohs(*phdr);
80 
81 	/* Make sure the version is correct */
82 	ver = (hdr & QCA_HDR_RECV_VERSION_MASK) >> QCA_HDR_RECV_VERSION_S;
83 	if (unlikely(ver != QCA_HDR_VERSION))
84 		return NULL;
85 
86 	/* Remove QCA tag and recalculate checksum */
87 	skb_pull_rcsum(skb, QCA_HDR_LEN);
88 	memmove(skb->data - ETH_HLEN, skb->data - ETH_HLEN - QCA_HDR_LEN,
89 		ETH_HLEN - QCA_HDR_LEN);
90 
91 	/* Get source port information */
92 	port = (hdr & QCA_HDR_RECV_SOURCE_PORT_MASK);
93 
94 	skb->dev = dsa_master_find_slave(dev, 0, port);
95 	if (!skb->dev)
96 		return NULL;
97 
98 	return skb;
99 }
100 
101 const struct dsa_device_ops qca_netdev_ops = {
102 	.xmit	= qca_tag_xmit,
103 	.rcv	= qca_tag_rcv,
104 };
105