1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Copyright (c) 2019 Pengutronix, Oleksij Rempel <kernel@pengutronix.de>
 4 */
 5
 6
 7#include <linux/bitfield.h>
 8#include <linux/etherdevice.h>
 9
10#include "dsa_priv.h"
11
12#define AR9331_HDR_LEN			2
13#define AR9331_HDR_VERSION		1
14
15#define AR9331_HDR_VERSION_MASK		GENMASK(15, 14)
16#define AR9331_HDR_PRIORITY_MASK	GENMASK(13, 12)
17#define AR9331_HDR_TYPE_MASK		GENMASK(10, 8)
18#define AR9331_HDR_BROADCAST		BIT(7)
19#define AR9331_HDR_FROM_CPU		BIT(6)
20/* AR9331_HDR_RESERVED - not used or may be version field.
21 * According to the AR8216 doc it should 0b10. On AR9331 it is 0b11 on RX path
22 * and should be set to 0b11 to make it work.
23 */
24#define AR9331_HDR_RESERVED_MASK	GENMASK(5, 4)
25#define AR9331_HDR_PORT_NUM_MASK	GENMASK(3, 0)
26
27static struct sk_buff *ar9331_tag_xmit(struct sk_buff *skb,
28				       struct net_device *dev)
29{
30	struct dsa_port *dp = dsa_slave_to_port(dev);
31	__le16 *phdr;
32	u16 hdr;
33
34	if (skb_cow_head(skb, AR9331_HDR_LEN) < 0)
35		return NULL;
36
37	phdr = skb_push(skb, AR9331_HDR_LEN);
38
39	hdr = FIELD_PREP(AR9331_HDR_VERSION_MASK, AR9331_HDR_VERSION);
40	hdr |= AR9331_HDR_FROM_CPU | dp->index;
41	/* 0b10 for AR8216 and 0b11 for AR9331 */
42	hdr |= AR9331_HDR_RESERVED_MASK;
43
44	phdr[0] = cpu_to_le16(hdr);
45
46	return skb;
47}
48
49static struct sk_buff *ar9331_tag_rcv(struct sk_buff *skb,
50				      struct net_device *ndev,
51				      struct packet_type *pt)
52{
53	u8 ver, port;
54	u16 hdr;
55
56	if (unlikely(!pskb_may_pull(skb, AR9331_HDR_LEN)))
57		return NULL;
58
59	hdr = le16_to_cpu(*(__le16 *)skb_mac_header(skb));
60
61	ver = FIELD_GET(AR9331_HDR_VERSION_MASK, hdr);
62	if (unlikely(ver != AR9331_HDR_VERSION)) {
63		netdev_warn_once(ndev, "%s:%i wrong header version 0x%2x\n",
64				 __func__, __LINE__, hdr);
65		return NULL;
66	}
67
68	if (unlikely(hdr & AR9331_HDR_FROM_CPU)) {
69		netdev_warn_once(ndev, "%s:%i packet should not be from cpu 0x%2x\n",
70				 __func__, __LINE__, hdr);
71		return NULL;
72	}
73
74	skb_pull_rcsum(skb, AR9331_HDR_LEN);
75
76	/* Get source port information */
77	port = FIELD_GET(AR9331_HDR_PORT_NUM_MASK, hdr);
78
79	skb->dev = dsa_master_find_slave(ndev, 0, port);
80	if (!skb->dev)
81		return NULL;
82
83	return skb;
84}
85
86static const struct dsa_device_ops ar9331_netdev_ops = {
87	.name	= "ar9331",
88	.proto	= DSA_TAG_PROTO_AR9331,
89	.xmit	= ar9331_tag_xmit,
90	.rcv	= ar9331_tag_rcv,
91	.overhead = AR9331_HDR_LEN,
92};
93
94MODULE_LICENSE("GPL v2");
95MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_AR9331);
96module_dsa_tag_driver(ar9331_netdev_ops);