[people/arne_f/kernel.git] / net / dsa / tag_lan9303.c

/*
 * 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 "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

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");
		return NULL;
	}

	/* 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;
}

static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
			struct packet_type *pt)
{
	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 >= ds->num_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,
};
Commit	Line	Data
e8fe177a JB	1	/*
	2	* Copyright (C) 2017 Pengutronix, Juergen Borleis <jbe@pengutronix.de>
	3	*
	4	* This program is free software; you can redistribute it and/or
	5	* modify it under the terms of the GNU General Public License
	6	* 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	#include <linux/list.h>
	16	#include <linux/slab.h>
ea5dd34b	17
e8fe177a JB	18	#include "dsa_priv.h"
	19
	20	/* To define the outgoing port and to discover the incoming port a regular
	21	* VLAN tag is used by the LAN9303. But its VID meaning is 'special':
	22	*
	23	* Dest MAC Src MAC TAG Type
	24	* ...\| 1 2 3 4 5 6 \| 1 2 3 4 5 6 \| 1 2 3 4 \| 1 2 \|...
	25	* \|<------->\|
	26	* TAG:
	27	* \|<------------->\|
	28	* \| 1 2 \| 3 4 \|
	29	* TPID VID
	30	* 0x8100
	31	*
	32	* VID bit 3 indicates a request for an ALR lookup.
	33	*
	34	* If VID bit 3 is zero, then bits 0 and 1 specify the destination port
	35	* (0, 1, 2) or broadcast (3) or the source port (1, 2).
	36	*
	37	* VID bit 4 is used to specify if the STP port state should be overridden.
	38	* Required when no forwarding between the external ports should happen.
	39	*/
	40
	41	#define LAN9303_TAG_LEN 4
e8fe177a JB	42
	43	static struct sk_buff lan9303_xmit(struct sk_buff skb, struct net_device *dev)
	44	{
	45	struct dsa_slave_priv *p = netdev_priv(dev);
	46	u16 *lan9303_tag;
	47
	48	/* insert a special VLAN tag between the MAC addresses
	49	* and the current ethertype field.
	50	*/
	51	if (skb_cow_head(skb, LAN9303_TAG_LEN) < 0) {
	52	dev_dbg(&dev->dev,
	53	"Cannot make room for the special tag. Dropping packet\n");
fe47d563	54	return NULL;
e8fe177a JB	55	}
	56
	57	/* provide 'LAN9303_TAG_LEN' bytes additional space */
	58	skb_push(skb, LAN9303_TAG_LEN);
	59
	60	/* make room between MACs and Ether-Type */
	61	memmove(skb->data, skb->data + LAN9303_TAG_LEN, 2 * ETH_ALEN);
	62
	63	lan9303_tag = (u16 )(skb->data + 2 ETH_ALEN);
	64	lan9303_tag[0] = htons(ETH_P_8021Q);
	65	lan9303_tag[1] = htons(p->dp->index \| BIT(4));
	66
	67	return skb;
e8fe177a JB	68	}
	69
	70	static struct sk_buff lan9303_rcv(struct sk_buff skb, struct net_device *dev,
89e49506	71	struct packet_type *pt)
e8fe177a JB	72	{
	73	u16 *lan9303_tag;
	74	struct dsa_switch_tree *dst = dev->dsa_ptr;
	75	struct dsa_switch *ds;
	76	unsigned int source_port;
	77
e8fe177a JB	78	ds = dst->ds[0];
	79
	80	if (unlikely(!ds)) {
	81	dev_warn_ratelimited(&dev->dev, "Dropping packet, due to missing DSA switch device\n");
	82	return NULL;
	83	}
	84
	85	if (unlikely(!pskb_may_pull(skb, LAN9303_TAG_LEN))) {
	86	dev_warn_ratelimited(&dev->dev,
	87	"Dropping packet, cannot pull\n");
	88	return NULL;
	89	}
	90
	91	/* '->data' points into the middle of our special VLAN tag information:
	92	*
	93	* ~ MAC src \| 0x81 \| 0x00 \| 0xyy \| 0xzz \| ether type
	94	* ^
	95	* ->data
	96	*/
	97	lan9303_tag = (u16 *)(skb->data - 2);
	98
	99	if (lan9303_tag[0] != htons(ETH_P_8021Q)) {
	100	dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid VLAN marker\n");
	101	return NULL;
	102	}
	103
	104	source_port = ntohs(lan9303_tag[1]) & 0x3;
	105
274cdb46	106	if (source_port >= ds->num_ports) {
e8fe177a JB	107	dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid source port\n");
	108	return NULL;
	109	}
	110
	111	if (!ds->ports[source_port].netdev) {
	112	dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid netdev or device\n");
	113	return NULL;
	114	}
	115
	116	/* remove the special VLAN tag between the MAC addresses
	117	* and the current ethertype field.
	118	*/
	119	skb_pull_rcsum(skb, 2 + 2);
	120	memmove(skb->data - ETH_HLEN, skb->data - (ETH_HLEN + LAN9303_TAG_LEN),
	121	2 * ETH_ALEN);
	122
	123	/* forward the packet to the dedicated interface */
	124	skb->dev = ds->ports[source_port].netdev;
	125
	126	return skb;
	127	}
	128
	129	const struct dsa_device_ops lan9303_netdev_ops = {
	130	.xmit = lan9303_xmit,
	131	.rcv = lan9303_rcv,
	132	};