diff options
Diffstat (limited to 'net/dsa/tag_lan9303.c')
| -rw-r--r-- | net/dsa/tag_lan9303.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/net/dsa/tag_lan9303.c b/net/dsa/tag_lan9303.c new file mode 100644 index 000000000000..70130ed5c21a --- /dev/null +++ b/net/dsa/tag_lan9303.c @@ -0,0 +1,136 @@ +/* + * Copyright (C) 2017 Pengutronix, Juergen Borleis <jbe@pengutronix.de> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + */ +#include <linux/etherdevice.h> +#include <linux/list.h> +#include <linux/slab.h> +#include <net/dsa.h> +#include "dsa_priv.h" + +/* To define the outgoing port and to discover the incoming port a regular + * VLAN tag is used by the LAN9303. But its VID meaning is 'special': + * + * Dest MAC Src MAC TAG Type + * ...| 1 2 3 4 5 6 | 1 2 3 4 5 6 | 1 2 3 4 | 1 2 |... + * |<------->| + * TAG: + * |<------------->| + * | 1 2 | 3 4 | + * TPID VID + * 0x8100 + * + * VID bit 3 indicates a request for an ALR lookup. + * + * If VID bit 3 is zero, then bits 0 and 1 specify the destination port + * (0, 1, 2) or broadcast (3) or the source port (1, 2). + * + * VID bit 4 is used to specify if the STP port state should be overridden. + * Required when no forwarding between the external ports should happen. + */ + +#define LAN9303_TAG_LEN 4 +#define LAN9303_MAX_PORTS 3 + +static struct sk_buff *lan9303_xmit(struct sk_buff *skb, struct net_device *dev) +{ + struct dsa_slave_priv *p = netdev_priv(dev); + u16 *lan9303_tag; + + /* insert a special VLAN tag between the MAC addresses + * and the current ethertype field. + */ + if (skb_cow_head(skb, LAN9303_TAG_LEN) < 0) { + dev_dbg(&dev->dev, + "Cannot make room for the special tag. Dropping packet\n"); + goto out_free; + } + + /* provide 'LAN9303_TAG_LEN' bytes additional space */ + skb_push(skb, LAN9303_TAG_LEN); + + /* make room between MACs and Ether-Type */ + memmove(skb->data, skb->data + LAN9303_TAG_LEN, 2 * ETH_ALEN); + + lan9303_tag = (u16 *)(skb->data + 2 * ETH_ALEN); + lan9303_tag[0] = htons(ETH_P_8021Q); + lan9303_tag[1] = htons(p->dp->index | BIT(4)); + + return skb; +out_free: + kfree_skb(skb); + return NULL; +} + +static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev, + struct packet_type *pt, struct net_device *orig_dev) +{ + u16 *lan9303_tag; + struct dsa_switch_tree *dst = dev->dsa_ptr; + struct dsa_switch *ds; + unsigned int source_port; + + ds = dst->ds[0]; + + if (unlikely(!ds)) { + dev_warn_ratelimited(&dev->dev, "Dropping packet, due to missing DSA switch device\n"); + return NULL; + } + + if (unlikely(!pskb_may_pull(skb, LAN9303_TAG_LEN))) { + dev_warn_ratelimited(&dev->dev, + "Dropping packet, cannot pull\n"); + return NULL; + } + + /* '->data' points into the middle of our special VLAN tag information: + * + * ~ MAC src | 0x81 | 0x00 | 0xyy | 0xzz | ether type + * ^ + * ->data + */ + lan9303_tag = (u16 *)(skb->data - 2); + + if (lan9303_tag[0] != htons(ETH_P_8021Q)) { + dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid VLAN marker\n"); + return NULL; + } + + source_port = ntohs(lan9303_tag[1]) & 0x3; + + if (source_port >= LAN9303_MAX_PORTS) { + dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid source port\n"); + return NULL; + } + + if (!ds->ports[source_port].netdev) { + dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid netdev or device\n"); + return NULL; + } + + /* remove the special VLAN tag between the MAC addresses + * and the current ethertype field. + */ + skb_pull_rcsum(skb, 2 + 2); + memmove(skb->data - ETH_HLEN, skb->data - (ETH_HLEN + LAN9303_TAG_LEN), + 2 * ETH_ALEN); + + /* forward the packet to the dedicated interface */ + skb->dev = ds->ports[source_port].netdev; + + return skb; +} + +const struct dsa_device_ops lan9303_netdev_ops = { + .xmit = lan9303_xmit, + .rcv = lan9303_rcv, +}; |