[mirror_ubuntu-eoan-kernel.git] / net / dsa / tag_lan9303.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2017 Pengutronix, Juergen Borleis <jbe@pengutronix.de>
 */
#include <linux/dsa/lan9303.h>
#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
# define LAN9303_TAG_TX_USE_ALR BIT(3)
# define LAN9303_TAG_TX_STP_OVERRIDE BIT(4)
# define LAN9303_TAG_RX_IGMP BIT(3)
# define LAN9303_TAG_RX_STP BIT(4)
# define LAN9303_TAG_RX_TRAPPED_TO_CPU (LAN9303_TAG_RX_IGMP | \
					LAN9303_TAG_RX_STP)

/* Decide whether to transmit using ALR lookup, or transmit directly to
 * port using tag. ALR learning is performed only when using ALR lookup.
 * If the two external ports are bridged and the frame is unicast,
 * then use ALR lookup to allow ALR learning on CPU port.
 * Otherwise transmit directly to port with STP state override.
 * See also: lan9303_separate_ports() and lan9303.pdf 6.4.10.1
 */
static int lan9303_xmit_use_arl(struct dsa_port *dp, u8 *dest_addr)
{
	struct lan9303 *chip = dp->ds->priv;

	return chip->is_bridged && !is_multicast_ether_addr(dest_addr);
}

static struct sk_buff *lan9303_xmit(struct sk_buff *skb, struct net_device *dev)
{
	struct dsa_port *dp = dsa_slave_to_port(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] = lan9303_xmit_use_arl(dp, skb->data) ?
				LAN9303_TAG_TX_USE_ALR :
				dp->index | LAN9303_TAG_TX_STP_OVERRIDE;
	lan9303_tag[1] = htons(lan9303_tag[1]);

	return skb;
}

static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
				   struct packet_type *pt)
{
	u16 *lan9303_tag;
	u16 lan9303_tag1;
	unsigned int source_port;

	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;
	}

	lan9303_tag1 = ntohs(lan9303_tag[1]);
	source_port = lan9303_tag1 & 0x3;

	skb->dev = dsa_master_find_slave(dev, 0, source_port);
	if (!skb->dev) {
		dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid source port\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);
	skb->offload_fwd_mark = !(lan9303_tag1 & LAN9303_TAG_RX_TRAPPED_TO_CPU);

	return skb;
}

const struct dsa_device_ops lan9303_netdev_ops = {
	.name = "lan9303",
	.xmit = lan9303_xmit,
	.rcv = lan9303_rcv,
	.overhead = LAN9303_TAG_LEN,
};
Commit	Line	Data
dfedd3b6	1	// SPDX-License-Identifier: GPL-2.0
e8fe177a JB	2	/*
e8fe177a JB	3	* Copyright (C) 2017 Pengutronix, Juergen Borleis <jbe@pengutronix.de>
e8fe177a	4	*/
535f010d	5	#include <linux/dsa/lan9303.h>
e8fe177a JB	6	#include <linux/etherdevice.h>
	7	#include <linux/list.h>
	8	#include <linux/slab.h>
ea5dd34b	9
e8fe177a JB	10	#include "dsa_priv.h"
	11
	12	/* To define the outgoing port and to discover the incoming port a regular
	13	* VLAN tag is used by the LAN9303. But its VID meaning is 'special':
	14	*
	15	* Dest MAC Src MAC TAG Type
	16	* ...\| 1 2 3 4 5 6 \| 1 2 3 4 5 6 \| 1 2 3 4 \| 1 2 \|...
	17	* \|<------->\|
	18	* TAG:
	19	* \|<------------->\|
	20	* \| 1 2 \| 3 4 \|
	21	* TPID VID
	22	* 0x8100
	23	*
	24	* VID bit 3 indicates a request for an ALR lookup.
	25	*
	26	* If VID bit 3 is zero, then bits 0 and 1 specify the destination port
	27	* (0, 1, 2) or broadcast (3) or the source port (1, 2).
	28	*
	29	* VID bit 4 is used to specify if the STP port state should be overridden.
	30	* Required when no forwarding between the external ports should happen.
	31	*/
	32
	33	#define LAN9303_TAG_LEN 4
535f010d EH	34	# define LAN9303_TAG_TX_USE_ALR BIT(3)
535f010d EH	35	# define LAN9303_TAG_TX_STP_OVERRIDE BIT(4)
1a48fbd9 EH	36	# define LAN9303_TAG_RX_IGMP BIT(3)
	37	# define LAN9303_TAG_RX_STP BIT(4)
	38	# define LAN9303_TAG_RX_TRAPPED_TO_CPU (LAN9303_TAG_RX_IGMP \| \
	39	LAN9303_TAG_RX_STP)
535f010d EH	40
	41	/* Decide whether to transmit using ALR lookup, or transmit directly to
	42	* port using tag. ALR learning is performed only when using ALR lookup.
909fb9ae	43	* If the two external ports are bridged and the frame is unicast,
535f010d EH	44	* then use ALR lookup to allow ALR learning on CPU port.
	45	* Otherwise transmit directly to port with STP state override.
	46	* See also: lan9303_separate_ports() and lan9303.pdf 6.4.10.1
	47	*/
	48	static int lan9303_xmit_use_arl(struct dsa_port dp, u8 dest_addr)
	49	{
	50	struct lan9303 *chip = dp->ds->priv;
	51
909fb9ae	52	return chip->is_bridged && !is_multicast_ether_addr(dest_addr);
535f010d	53	}
e8fe177a JB	54
	55	static struct sk_buff lan9303_xmit(struct sk_buff skb, struct net_device *dev)
	56	{
d945097b	57	struct dsa_port *dp = dsa_slave_to_port(dev);
e8fe177a JB	58	u16 *lan9303_tag;
	59
	60	/* insert a special VLAN tag between the MAC addresses
	61	* and the current ethertype field.
	62	*/
	63	if (skb_cow_head(skb, LAN9303_TAG_LEN) < 0) {
	64	dev_dbg(&dev->dev,
	65	"Cannot make room for the special tag. Dropping packet\n");
fe47d563	66	return NULL;
e8fe177a JB	67	}
	68
	69	/* provide 'LAN9303_TAG_LEN' bytes additional space */
	70	skb_push(skb, LAN9303_TAG_LEN);
	71
	72	/* make room between MACs and Ether-Type */
	73	memmove(skb->data, skb->data + LAN9303_TAG_LEN, 2 * ETH_ALEN);
	74
	75	lan9303_tag = (u16 )(skb->data + 2 ETH_ALEN);
	76	lan9303_tag[0] = htons(ETH_P_8021Q);
535f010d EH	77	lan9303_tag[1] = lan9303_xmit_use_arl(dp, skb->data) ?
	78	LAN9303_TAG_TX_USE_ALR :
	79	dp->index \| LAN9303_TAG_TX_STP_OVERRIDE;
	80	lan9303_tag[1] = htons(lan9303_tag[1]);
e8fe177a JB	81
e8fe177a JB	82	return skb;
e8fe177a JB	83	}
	84
	85	static struct sk_buff lan9303_rcv(struct sk_buff skb, struct net_device *dev,
92f25caf	86	struct packet_type *pt)
e8fe177a JB	87	{
e8fe177a JB	88	u16 *lan9303_tag;
1a48fbd9	89	u16 lan9303_tag1;
e8fe177a JB	90	unsigned int source_port;
e8fe177a JB	91
e8fe177a JB	92	if (unlikely(!pskb_may_pull(skb, LAN9303_TAG_LEN))) {
	93	dev_warn_ratelimited(&dev->dev,
	94	"Dropping packet, cannot pull\n");
	95	return NULL;
	96	}
	97
	98	/* '->data' points into the middle of our special VLAN tag information:
	99	*
	100	* ~ MAC src \| 0x81 \| 0x00 \| 0xyy \| 0xzz \| ether type
	101	* ^
	102	* ->data
	103	*/
	104	lan9303_tag = (u16 *)(skb->data - 2);
	105
	106	if (lan9303_tag[0] != htons(ETH_P_8021Q)) {
	107	dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid VLAN marker\n");
	108	return NULL;
	109	}
	110
1a48fbd9 EH	111	lan9303_tag1 = ntohs(lan9303_tag[1]);
1a48fbd9 EH	112	source_port = lan9303_tag1 & 0x3;
e8fe177a	113
2231c43b	114	skb->dev = dsa_master_find_slave(dev, 0, source_port);
3775b1b7	115	if (!skb->dev) {
e8fe177a JB	116	dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid source port\n");
	117	return NULL;
	118	}
	119
e8fe177a JB	120	/* remove the special VLAN tag between the MAC addresses
	121	* and the current ethertype field.
	122	*/
	123	skb_pull_rcsum(skb, 2 + 2);
	124	memmove(skb->data - ETH_HLEN, skb->data - (ETH_HLEN + LAN9303_TAG_LEN),
	125	2 * ETH_ALEN);
1a48fbd9	126	skb->offload_fwd_mark = !(lan9303_tag1 & LAN9303_TAG_RX_TRAPPED_TO_CPU);
4672cd36	127
e8fe177a JB	128	return skb;
	129	}
	130
	131	const struct dsa_device_ops lan9303_netdev_ops = {
875138f8	132	.name = "lan9303",
e8fe177a JB	133	.xmit = lan9303_xmit,
e8fe177a JB	134	.rcv = lan9303_rcv,
a5dd3087	135	.overhead = LAN9303_TAG_LEN,
e8fe177a	136	};