Subject: [PATCH v2] net/hsr: Add support for the High-availability Seamless Redundancy protocol (HSRv0)

From: Arvid Brodin <[email-masked]>
Date: Wed, 26 Jun 2013 17:16:11 +0200

High-availability Seamless Redundancy ("HSR") provides instant failover
redundancy for Ethernet networks. It requires a special network topology where
all nodes are connected in a ring (each node having two physical network
interfaces). It is suited for applications that demand high availability and
very short reaction time.

HSR acts on the Ethernet layer, using a registered Ethernet protocol type to
send special HSR frames in both directions over the ring. The driver creates
virtual network interfaces that can be used just like any ordinary Linux
network interface, for IP/TCP/UDP traffic etc. All nodes in the network ring
must be HSR capable.

This code is a "best effort" to comply with the HSR standard as described in
IEC 62439-3:2010 (HSRv0).

Signed-off-by: Arvid Brodin <[email-masked]>

---

This is a patch against net-next (2013-06-20).

The code has been statically analysed using sparse (no problems detected).

kmemleak has been used to detect memory leaks (no known leaks exist).

The code passes checkpatch.pl with the option --max-line-length=83, except for
CamelCase warnings. CamelCase is used in the IEC standard to describe field
names, and these names have been used in the code. This usage is intentional.

The code has been tested extensively on rings of up to 32 avr32-based nodes.
Less intense testing has included an x86_64 (SMP) system, and running HSR
over a USB-to-Ethernet device.

Earlier RFC:s:
RFC v1: http://www.spinics.net/lists/netdev/msg192817.html
RFC v2: http://www.spinics.net/lists/netdev/msg203397.html
RFC v3: http://www.spinics.net/lists/netdev/msg207816.html
RFC v4: http://www.spinics.net/lists/netdev/msg213309.html

Thanks to Stephen Hemminger, Joe Perches, and others for their comments on
these RFC:s.

Changes since v1:

* Aligned newlines with open parenthesis (Joe Perches)
* Removed unneccessary WARN_ON_ONCE from is_hsr_master() (Joe Perches)
* Removed deprecated comments about "actually signed" for HSR_A_IFn_AGE (Joe Perches)
* Broke out userspace hsr_netlink.h into include/uapi/linux/ (Joe Perches)
* Use netif_oper_up() to check for operational state UP (Stephen Hemminger)

Possibly unresolved: 

* dev_base_lock vs rtnl_mutex when setting operstate? (Stephen Hemminger)
* Move more (local) header files into include/net/? (checkpatch still warns
  about CamelCase) (Joe Perches / with help from David Miller?)

 include/uapi/linux/hsr_netlink.h |  50 ++++
 include/uapi/linux/if_ether.h    |   1 +
 include/uapi/linux/if_link.h     |  13 +
 net/Kconfig                      |   1 +
 net/Makefile                     |   1 +
 net/hsr/Kconfig                  |  27 ++
 net/hsr/Makefile                 |   7 +
 net/hsr/hsr_device.c             | 585 +++++++++++++++++++++++++++++++++++++++
 net/hsr/hsr_device.h             |  30 ++
 net/hsr/hsr_framereg.c           | 502 +++++++++++++++++++++++++++++++++
 net/hsr/hsr_framereg.h           |  54 ++++
 net/hsr/hsr_main.c               | 457 ++++++++++++++++++++++++++++++
 net/hsr/hsr_main.h               | 167 +++++++++++
 net/hsr/hsr_netlink.c            | 458 ++++++++++++++++++++++++++++++
 net/hsr/hsr_netlink.h            |  31 +++
 15 files changed, 2384 insertions(+)
 create mode 100644 include/uapi/linux/hsr_netlink.h
 create mode 100644 net/hsr/Kconfig
 create mode 100644 net/hsr/Makefile
 create mode 100644 net/hsr/hsr_device.c
 create mode 100644 net/hsr/hsr_device.h
 create mode 100644 net/hsr/hsr_framereg.c
 create mode 100644 net/hsr/hsr_framereg.h
 create mode 100644 net/hsr/hsr_main.c
 create mode 100644 net/hsr/hsr_main.h
 create mode 100644 net/hsr/hsr_netlink.c
 create mode 100644 net/hsr/hsr_netlink.h

diff --git a/include/uapi/linux/hsr_netlink.h b/include/uapi/linux/hsr_netlink.h
new file mode 100644
index 0000000..2475cb8
--- /dev/null
+++ b/include/uapi/linux/hsr_netlink.h
@@ -0,0 +1,50 @@
+/*
+ * Copyright 2011-2013 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2013 Arvid Brodin, [email-masked]
+ */
+
+#ifndef __UAPI_HSR_NETLINK_H
+#define __UAPI_HSR_NETLINK_H
+
+/* Generic Netlink HSR family definition
+ */
+
+/* attributes */
+enum {
+	HSR_A_UNSPEC,
+	HSR_A_NODE_ADDR,
+	HSR_A_IFINDEX,
+	HSR_A_IF1_AGE,
+	HSR_A_IF2_AGE,
+	HSR_A_NODE_ADDR_B,
+	HSR_A_IF1_SEQ,
+	HSR_A_IF2_SEQ,
+	HSR_A_IF1_IFINDEX,
+	HSR_A_IF2_IFINDEX,
+	HSR_A_ADDR_B_IFINDEX,
+	__HSR_A_MAX,
+};
+#define HSR_A_MAX (__HSR_A_MAX - 1)
+
+
+/* commands */
+enum {
+	HSR_C_UNSPEC,
+	HSR_C_RING_ERROR,
+	HSR_C_NODE_DOWN,
+	HSR_C_GET_NODE_STATUS,
+	HSR_C_SET_NODE_STATUS,
+	HSR_C_GET_NODE_LIST,
+	HSR_C_SET_NODE_LIST,
+	__HSR_C_MAX,
+};
+#define HSR_C_MAX (__HSR_C_MAX - 1)
+
+#endif /* __UAPI_HSR_NETLINK_H */
diff --git a/include/uapi/linux/if_ether.h b/include/uapi/linux/if_ether.h
index ade07f1..2ce0f6a 100644
--- a/include/uapi/linux/if_ether.h
+++ b/include/uapi/linux/if_ether.h
@@ -85,6 +85,7 @@
 #define ETH_P_8021AH	0x88E7          /* 802.1ah Backbone Service Tag */
 #define ETH_P_MVRP	0x88F5          /* 802.1Q MVRP                  */
 #define ETH_P_1588	0x88F7		/* IEEE 1588 Timesync */
+#define ETH_P_PRP	0x88FB		/* IEC 62439-3 PRP/HSRv0	*/
 #define ETH_P_FCOE	0x8906		/* Fibre Channel over Ethernet  */
 #define ETH_P_TDLS	0x890D          /* TDLS */
 #define ETH_P_FIP	0x8914		/* FCoE Initialization Protocol */
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index 03f6170..5b164b4 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -467,4 +467,17 @@ enum {
 
 #define IFLA_IPOIB_MAX (__IFLA_IPOIB_MAX - 1)
 
+
+/* HSR section */
+
+enum {
+	IFLA_HSR_UNSPEC,
+	IFLA_HSR_SLAVE1,
+	IFLA_HSR_SLAVE2,
+	IFLA_HSR_MULTICAST_SPEC,
+	__IFLA_HSR_MAX,
+};
+
+#define IFLA_HSR_MAX (__IFLA_HSR_MAX - 1)
+
 #endif /* _UAPI_LINUX_IF_LINK_H */
diff --git a/net/Kconfig b/net/Kconfig
index 51da839..e0c621a 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -219,6 +219,7 @@ source "net/openvswitch/Kconfig"
 source "net/vmw_vsock/Kconfig"
 source "net/netlink/Kconfig"
 source "net/mpls/Kconfig"
+source "net/hsr/Kconfig"
 
 config RPS
 	boolean
diff --git a/net/Makefile b/net/Makefile
index 9492e8c..8fa2f91 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -71,3 +71,4 @@ obj-$(CONFIG_NFC)		+= nfc/
 obj-$(CONFIG_OPENVSWITCH)	+= openvswitch/
 obj-$(CONFIG_VSOCKETS)	+= vmw_vsock/
 obj-$(CONFIG_NET_MPLS_GSO)	+= mpls/
+obj-$(CONFIG_HSR)		+= hsr/
diff --git a/net/hsr/Kconfig b/net/hsr/Kconfig
new file mode 100644
index 0000000..0d3d709
--- /dev/null
+++ b/net/hsr/Kconfig
@@ -0,0 +1,27 @@
+#
+# IEC 62439-3 High-availability Seamless Redundancy
+#
+
+config HSR
+	tristate "High-availability Seamless Redundancy (HSR)"
+	---help---
+	  If you say Y here, then your Linux box will be able to act as a
+	  DANH ("Doubly attached node implementing HSR"). For this to work,
+	  your Linux box needs (at least) two physical Ethernet interfaces,
+	  and it must be connected as a node in a ring network together with
+	  other HSR capable nodes.
+
+	  All Ethernet frames sent over the hsr device will be sent in both
+	  directions on the ring (over both slave ports), giving a redundant,
+	  instant fail-over network. Each HSR node in the ring acts like a
+	  bridge for HSR frames, but filters frames that have been forwarded
+	  earlier.
+
+	  This code is a "best effort" to comply with the HSR standard as
+	  described in IEC 62439-3:2010 (HSRv0), but no compliancy tests have
+	  been made.
+
+	  You need to perform any and all necessary tests yourself before
+	  relying on this code in a safety critical system!
+
+	  If unsure, say N.
diff --git a/net/hsr/Makefile b/net/hsr/Makefile
new file mode 100644
index 0000000..b68359f
--- /dev/null
+++ b/net/hsr/Makefile
@@ -0,0 +1,7 @@
+#
+# Makefile for HSR
+#
+
+obj-$(CONFIG_HSR)	+= hsr.o
+
+hsr-y			:= hsr_main.o hsr_framereg.o hsr_device.o hsr_netlink.o
diff --git a/net/hsr/hsr_device.c b/net/hsr/hsr_device.c
new file mode 100644
index 0000000..78f356e
--- /dev/null
+++ b/net/hsr/hsr_device.c
@@ -0,0 +1,585 @@
+/*
+ * Copyright 2011-2013 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2013 Arvid Brodin, [email-masked]
+ *
+ * This file contains device methods for creating, using and destroying
+ * virtual HSR devices.
+ */
+
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/etherdevice.h>
+#include <linux/if_arp.h>
+#include <linux/rtnetlink.h>
+#include <linux/pkt_sched.h>
+#include "hsr_device.h"
+#include "hsr_framereg.h"
+#include "hsr_main.h"
+
+
+static bool is_admin_up(struct net_device *dev)
+{
+	return dev && (dev->flags & IFF_UP);
+}
+
+static bool is_operstate_up(struct net_device *dev)
+{
+	return dev && netif_oper_up(dev);
+}
+
+static void __hsr_set_operstate(struct net_device *dev, int transition)
+{
+	if (dev->operstate != transition) {
+		write_lock_bh(&dev_base_lock);
+		dev->operstate = transition;
+		write_unlock_bh(&dev_base_lock);
+		netdev_state_change(dev);
+	}
+}
+
+void hsr_set_operstate(struct net_device *hsr_dev, struct net_device *slave1,
+		       struct net_device *slave2)
+{
+	if (!is_admin_up(hsr_dev)) {
+		__hsr_set_operstate(hsr_dev, IF_OPER_DOWN);
+		return;
+	}
+
+	if (is_operstate_up(slave1) || is_operstate_up(slave2))
+		__hsr_set_operstate(hsr_dev, IF_OPER_UP);
+	else
+		__hsr_set_operstate(hsr_dev, IF_OPER_LOWERLAYERDOWN);
+}
+
+void hsr_set_carrier(struct net_device *hsr_dev, struct net_device *slave1,
+		     struct net_device *slave2)
+{
+	if (is_operstate_up(slave1) || is_operstate_up(slave2))
+		netif_carrier_on(hsr_dev);
+	else
+		netif_carrier_off(hsr_dev);
+}
+
+
+void hsr_check_announce(struct net_device *hsr_dev, int old_operstate)
+{
+	struct hsr_priv *hsr_priv;
+
+	hsr_priv = netdev_priv(hsr_dev);
+
+	if ((hsr_dev->operstate == IF_OPER_UP) && (old_operstate != IF_OPER_UP)) {
+		/* Went up */
+		hsr_priv->announce_count = 0;
+		hsr_priv->announce_timer.expires = jiffies +
+				msecs_to_jiffies(HSR_ANNOUNCE_INTERVAL);
+		add_timer(&hsr_priv->announce_timer);
+	}
+
+	if ((hsr_dev->operstate != IF_OPER_UP) && (old_operstate == IF_OPER_UP))
+		/* Went down */
+		del_timer(&hsr_priv->announce_timer);
+}
+
+
+int hsr_get_max_mtu(struct hsr_priv *hsr_priv)
+{
+	int mtu_max;
+
+	if (hsr_priv->slave[0] && hsr_priv->slave[1])
+		mtu_max = min(hsr_priv->slave[0]->mtu, hsr_priv->slave[1]->mtu);
+	else if (hsr_priv->slave[0])
+		mtu_max = hsr_priv->slave[0]->mtu;
+	else if (hsr_priv->slave[1])
+		mtu_max = hsr_priv->slave[1]->mtu;
+	else
+		mtu_max = HSR_TAGLEN;
+
+	return mtu_max - HSR_TAGLEN;
+}
+
+static int hsr_dev_change_mtu(struct net_device *dev, int new_mtu)
+{
+	struct hsr_priv *hsr_priv;
+
+	hsr_priv = netdev_priv(dev);
+
+	if (new_mtu > hsr_get_max_mtu(hsr_priv)) {
+		netdev_info(hsr_priv->dev, "A HSR master's MTU cannot be greater than the smallest MTU of its slaves minus the HSR Tag length (%d octets).\n",
+			    HSR_TAGLEN);
+		return -EINVAL;
+	}
+
+	dev->mtu = new_mtu;
+
+	return 0;
+}
+
+static int hsr_dev_open(struct net_device *dev)
+{
+	struct hsr_priv *hsr_priv;
+
+	hsr_priv = netdev_priv(dev);
+
+	if (hsr_priv->slave[0])
+		dev_open(hsr_priv->slave[0]);
+	if (hsr_priv->slave[1])
+		dev_open(hsr_priv->slave[1]);
+
+	return 0;
+}
+
+static int hsr_dev_close(struct net_device *dev)
+{
+	/* Nothing to do here. We could try to restore the state of the slaves
+	 * to what they were before being changed by the hsr master dev's state,
+	 * but they might have been changed manually in the mean time too, so
+	 * taking them up or down here might be confusing and is probably not a
+	 * good idea.
+	 */
+	return 0;
+}
+
+
+static void hsr_fill_tag(struct hsr_ethhdr *hsr_ethhdr, struct hsr_priv *hsr_priv)
+{
+	unsigned long irqflags;
+
+	/* IEC 62439-1:2010, p 48, says the 4-bit "path" field can take values
+	 * between 0001-1001 ("ring identifier", for regular HSR frames),
+	 * or 1111 ("HSR management", supervision frames). Unfortunately, the
+	 * spec writers forgot to explain what a "ring identifier" is, or
+	 * how it is used. So we just set this to 0001 for regular frames,
+	 * and 1111 for supervision frames.
+	 */
+	set_hsr_tag_path(&hsr_ethhdr->hsr_tag, 0x1);
+
+	/* IEC 62439-1:2010, p 12: "The link service data unit in an Ethernet
+	 * frame is the content of the frame located between the Length/Type
+	 * field and the Frame Check Sequence."
+	 *
+	 * IEC 62439-3, p 48, specifies the "original LPDU" to include the
+	 * original "LT" field (what "LT" means is not explained anywhere as
+	 * far as I can see - perhaps "Length/Type"?). So LSDU_size might
+	 * equal original length + 2.
+	 *   Also, the fact that this field is not used anywhere (might be used
+	 * by a RedBox connecting HSR and PRP nets?) means I cannot test its
+	 * correctness. Instead of guessing, I set this to 0 here, to make any
+	 * problems immediately apparent. Anyone using this driver with PRP/HSR
+	 * RedBoxes might need to fix this...
+	 */
+	set_hsr_tag_LSDU_size(&hsr_ethhdr->hsr_tag, 0);
+
+	spin_lock_irqsave(&hsr_priv->seqnr_lock, irqflags);
+	hsr_ethhdr->hsr_tag.sequence_nr = htons(hsr_priv->sequence_nr);
+	hsr_priv->sequence_nr++;
+	spin_unlock_irqrestore(&hsr_priv->seqnr_lock, irqflags);
+
+	hsr_ethhdr->hsr_tag.encap_proto = hsr_ethhdr->ethhdr.h_proto;
+
+	hsr_ethhdr->ethhdr.h_proto = htons(ETH_P_PRP);
+}
+
+static int slave_xmit(struct sk_buff *skb, struct hsr_priv *hsr_priv,
+		      enum hsr_dev_idx dev_idx)
+{
+	struct hsr_ethhdr *hsr_ethhdr;
+
+	hsr_ethhdr = (struct hsr_ethhdr *) skb->data;
+
+	skb->dev = hsr_priv->slave[dev_idx];
+
+	hsr_addr_subst_dest(hsr_priv, &hsr_ethhdr->ethhdr, dev_idx);
+
+	/* Address substitution (IEC62439-3 pp 26, 50): replace mac
+	 * address of outgoing frame with that of the outgoing slave's.
+	 */
+	memcpy(hsr_ethhdr->ethhdr.h_source, skb->dev->dev_addr, ETH_ALEN);
+
+	return dev_queue_xmit(skb);
+}
+
+
+static int hsr_dev_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct hsr_priv *hsr_priv;
+	struct hsr_ethhdr *hsr_ethhdr;
+	struct sk_buff *skb2;
+	int res1, res2;
+
+	hsr_priv = netdev_priv(dev);
+	hsr_ethhdr = (struct hsr_ethhdr *) skb->data;
+
+	if ((skb->protocol != htons(ETH_P_PRP)) ||
+	    (hsr_ethhdr->ethhdr.h_proto != htons(ETH_P_PRP))) {
+		hsr_fill_tag(hsr_ethhdr, hsr_priv);
+		skb->protocol = htons(ETH_P_PRP);
+	}
+
+	skb2 = pskb_copy(skb, GFP_ATOMIC);
+
+	res1 = NET_XMIT_DROP;
+	if (likely(hsr_priv->slave[HSR_DEV_SLAVE_A]))
+		res1 = slave_xmit(skb, hsr_priv, HSR_DEV_SLAVE_A);
+
+	res2 = NET_XMIT_DROP;
+	if (likely(skb2 && hsr_priv->slave[HSR_DEV_SLAVE_B]))
+		res2 = slave_xmit(skb2, hsr_priv, HSR_DEV_SLAVE_B);
+
+	if (likely(res1 == NET_XMIT_SUCCESS || res1 == NET_XMIT_CN ||
+		   res2 == NET_XMIT_SUCCESS || res2 == NET_XMIT_CN)) {
+		hsr_priv->dev->stats.tx_packets++;
+		hsr_priv->dev->stats.tx_bytes += skb->len;
+	} else {
+		hsr_priv->dev->stats.tx_dropped++;
+	}
+
+	return NETDEV_TX_OK;
+}
+
+
+static int hsr_header_create(struct sk_buff *skb, struct net_device *dev,
+			     unsigned short type, const void *daddr,
+			     const void *saddr, unsigned int len)
+{
+	int res;
+
+	/* Make room for the HSR tag now. We will fill it in later (in
+	 * hsr_dev_xmit)
+	 */
+	if (skb_headroom(skb) < HSR_TAGLEN + ETH_HLEN)
+		return -ENOBUFS;
+	skb_push(skb, HSR_TAGLEN);
+
+	/* To allow VLAN/HSR combos we should probably use
+	 * res = dev_hard_header(skb, dev, type, daddr, saddr, len + HSR_TAGLEN);
+	 * here instead. It would require other changes too, though - e.g.
+	 * separate headers for each slave etc...
+	 */
+	res = eth_header(skb, dev, type, daddr, saddr, len + HSR_TAGLEN);
+	if (res <= 0)
+		return res;
+	skb_reset_mac_header(skb);
+
+	return res + HSR_TAGLEN;
+}
+
+
+static const struct header_ops hsr_header_ops = {
+	.create	 = hsr_header_create,
+	.parse	 = eth_header_parse,
+};
+
+
+/* HSR:2010 supervision frames should be padded so that the whole frame,
+ * including headers and FCS, is 64 bytes (without VLAN).
+ */
+static int hsr_pad(int size)
+{
+	const int min_size = ETH_ZLEN - HSR_TAGLEN - ETH_HLEN;
+
+	if (size >= min_size)
+		return size;
+	return min_size;
+}
+
+static void send_hsr_supervision_frame(struct net_device *hsr_dev, u8 type)
+{
+	struct hsr_priv *hsr_priv;
+	struct sk_buff *skb;
+	int hlen, tlen;
+	struct hsr_sup_tag *hsr_stag;
+	struct hsr_sup_payload *hsr_sp;
+	unsigned long irqflags;
+
+	hlen = LL_RESERVED_SPACE(hsr_dev);
+	tlen = hsr_dev->needed_tailroom;
+	skb = alloc_skb(hsr_pad(sizeof(struct hsr_sup_payload)) + hlen + tlen,
+			GFP_ATOMIC);
+
+	if (skb == NULL)
+		return;
+
+	hsr_priv = netdev_priv(hsr_dev);
+
+	skb_reserve(skb, hlen);
+
+	skb->dev = hsr_dev;
+	skb->protocol = htons(ETH_P_PRP);
+	skb->priority = TC_PRIO_CONTROL;
+
+	if (dev_hard_header(skb, skb->dev, ETH_P_PRP,
+			    hsr_priv->sup_multicast_addr,
+			    skb->dev->dev_addr, skb->len) < 0)
+		goto out;
+
+	skb_pull(skb, sizeof(struct ethhdr));
+	hsr_stag = (typeof(hsr_stag)) skb->data;
+
+	set_hsr_stag_path(hsr_stag, 0xf);
+	set_hsr_stag_HSR_Ver(hsr_stag, 0);
+
+	spin_lock_irqsave(&hsr_priv->seqnr_lock, irqflags);
+	hsr_stag->sequence_nr = htons(hsr_priv->sequence_nr);
+	hsr_priv->sequence_nr++;
+	spin_unlock_irqrestore(&hsr_priv->seqnr_lock, irqflags);
+
+	hsr_stag->HSR_TLV_Type = type;
+	hsr_stag->HSR_TLV_Length = 12;
+
+	skb_push(skb, sizeof(struct ethhdr));
+
+	/* Payload: MacAddressA */
+	hsr_sp = (typeof(hsr_sp)) skb_put(skb, sizeof(*hsr_sp));
+	memcpy(hsr_sp->MacAddressA, hsr_dev->dev_addr, ETH_ALEN);
+
+	dev_queue_xmit(skb);
+	return;
+
+out:
+	kfree_skb(skb);
+}
+
+
+/* Announce (supervision frame) timer function
+ */
+static void hsr_announce(unsigned long data)
+{
+	struct hsr_priv *hsr_priv;
+
+	hsr_priv = (struct hsr_priv *) data;
+
+	if (hsr_priv->announce_count < 3) {
+		send_hsr_supervision_frame(hsr_priv->dev, HSR_TLV_ANNOUNCE);
+		hsr_priv->announce_count++;
+	} else {
+		send_hsr_supervision_frame(hsr_priv->dev, HSR_TLV_LIFE_CHECK);
+	}
+
+	if (hsr_priv->announce_count < 3)
+		hsr_priv->announce_timer.expires = jiffies +
+				msecs_to_jiffies(HSR_ANNOUNCE_INTERVAL);
+	else
+		hsr_priv->announce_timer.expires = jiffies +
+				msecs_to_jiffies(HSR_LIFE_CHECK_INTERVAL);
+
+	if (is_admin_up(hsr_priv->dev))
+		add_timer(&hsr_priv->announce_timer);
+}
+
+
+static void restore_slaves(struct net_device *hsr_dev)
+{
+	struct hsr_priv *hsr_priv;
+	int i;
+	int res;
+
+	hsr_priv = netdev_priv(hsr_dev);
+
+	rtnl_lock();
+
+	/* Restore promiscuity */
+	for (i = 0; i < 2; i++) {
+		if (!hsr_priv->slave[i])
+			continue;
+		res = dev_set_promiscuity(hsr_priv->slave[i], -1);
+		if (res)
+			netdev_info(hsr_dev, "Cannot restore slave promiscuity (%s, %d)\n",
+				    hsr_priv->slave[i]->name, res);
+	}
+
+	rtnl_unlock();
+}
+
+static void reclaim_hsr_dev(struct rcu_head *rh)
+{
+	struct hsr_priv *hsr_priv;
+
+	hsr_priv = container_of(rh, struct hsr_priv, rcu_head);
+	free_netdev(hsr_priv->dev);
+}
+
+
+/* According to comments in the declaration of struct net_device, this function
+ * is "Called from unregister, can be used to call free_netdev". Ok then...
+ */
+static void hsr_dev_destroy(struct net_device *hsr_dev)
+{
+	struct hsr_priv *hsr_priv;
+
+	hsr_priv = netdev_priv(hsr_dev);
+
+	del_timer(&hsr_priv->announce_timer);
+	unregister_hsr_master(hsr_priv);    /* calls list_del_rcu on hsr_priv */
+	restore_slaves(hsr_dev);
+	call_rcu(&hsr_priv->rcu_head, reclaim_hsr_dev);   /* reclaim hsr_priv */
+}
+
+static const struct net_device_ops hsr_device_ops = {
+	.ndo_change_mtu = hsr_dev_change_mtu,
+	.ndo_open = hsr_dev_open,
+	.ndo_stop = hsr_dev_close,
+	.ndo_start_xmit = hsr_dev_xmit,
+};
+
+
+void hsr_dev_setup(struct net_device *dev)
+{
+	random_ether_addr(dev->dev_addr);
+
+	ether_setup(dev);
+	dev->header_ops		 = &hsr_header_ops;
+	dev->netdev_ops		 = &hsr_device_ops;
+	dev->tx_queue_len	 = 0;
+
+	dev->destructor = hsr_dev_destroy;
+}
+
+
+/* If dev is a HSR master, return 1; otherwise, return 0.
+ */
+bool is_hsr_master(struct net_device *dev)
+{
+	return (dev->netdev_ops->ndo_start_xmit == hsr_dev_xmit);
+}
+
+static int check_slave_ok(struct net_device *dev)
+{
+	/* Don't allow HSR on non-ethernet like devices */
+	if ((dev->flags & IFF_LOOPBACK) || (dev->type != ARPHRD_ETHER) ||
+	    (dev->addr_len != ETH_ALEN)) {
+		netdev_info(dev, "Cannot use loopback or non-ethernet device as HSR slave.\n");
+		return -EINVAL;
+	}
+
+	/* Don't allow enslaving hsr devices */
+	if (is_hsr_master(dev)) {
+		netdev_info(dev, "Cannot create trees of HSR devices.\n");
+		return -EINVAL;
+	}
+
+	if (is_hsr_slave(dev)) {
+		netdev_info(dev, "This device is already a HSR slave.\n");
+		return -EINVAL;
+	}
+
+	if (dev->priv_flags & IFF_802_1Q_VLAN) {
+		netdev_info(dev, "HSR on top of VLAN is not yet supported in this driver.\n");
+		return -EINVAL;
+	}
+
+	/* HSR over bonded devices has not been tested, but I'm not sure it
+	 * won't work...
+	 */
+
+	return 0;
+}
+
+
+/* Default multicast address for HSR Supervision frames */
+static const unsigned char def_multicast_addr[ETH_ALEN] = {
+	0x01, 0x15, 0x4e, 0x00, 0x01, 0x00
+};
+
+int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *slave[2],
+		     unsigned char multicast_spec)
+{
+	struct hsr_priv *hsr_priv;
+	int i;
+	int res;
+
+	hsr_priv = netdev_priv(hsr_dev);
+	hsr_priv->dev = hsr_dev;
+	INIT_LIST_HEAD(&hsr_priv->node_db);
+	INIT_LIST_HEAD(&hsr_priv->self_node_db);
+	for (i = 0; i < 2; i++)
+		hsr_priv->slave[i] = slave[i];
+
+	spin_lock_init(&hsr_priv->seqnr_lock);
+	/* Overflow soon to find bugs easier: */
+	hsr_priv->sequence_nr = USHRT_MAX - 1024;
+
+	init_timer(&hsr_priv->announce_timer);
+	hsr_priv->announce_timer.function = hsr_announce;
+	hsr_priv->announce_timer.data = (unsigned long) hsr_priv;
+
+	memcpy(hsr_priv->sup_multicast_addr, def_multicast_addr, ETH_ALEN);
+	hsr_priv->sup_multicast_addr[ETH_ALEN - 1] = multicast_spec;
+
+/* FIXME: should I modify the value of these?
+ *
+ * - hsr_dev->flags - i.e.
+ *			IFF_MASTER/SLAVE?
+ * - hsr_dev->priv_flags - i.e.
+ *			IFF_EBRIDGE?
+ *			IFF_TX_SKB_SHARING?
+ *			IFF_HSR_MASTER/SLAVE?
+ */
+
+	for (i = 0; i < 2; i++) {
+		res = check_slave_ok(slave[i]);
+		if (res)
+			return res;
+	}
+
+	hsr_dev->features = slave[0]->features & slave[1]->features;
+	/* Prevent recursive tx locking */
+	hsr_dev->features |= NETIF_F_LLTX;
+	/* VLAN on top of HSR needs testing and probably some work on
+	 * hsr_header_create() etc.
+	 */
+	hsr_dev->features |= NETIF_F_VLAN_CHALLENGED;
+
+	/* Set hsr_dev's MAC address to that of mac_slave1 */
+	memcpy(hsr_dev->dev_addr, hsr_priv->slave[0]->dev_addr, ETH_ALEN);
+
+	/* Set required header length */
+	for (i = 0; i < 2; i++)
+		if (slave[i]->hard_header_len + HSR_TAGLEN >
+						hsr_dev->hard_header_len)
+			hsr_dev->hard_header_len =
+					slave[i]->hard_header_len + HSR_TAGLEN;
+
+	/* MTU */
+	for (i = 0; i < 2; i++)
+		if (slave[i]->mtu - HSR_TAGLEN < hsr_dev->mtu)
+			hsr_dev->mtu = slave[i]->mtu - HSR_TAGLEN;
+
+	/* Make sure the 1st call to netif_carrier_on() gets through */
+	netif_carrier_off(hsr_dev);
+
+	/* Promiscuity */
+	for (i = 0; i < 2; i++) {
+		res = dev_set_promiscuity(slave[i], 1);
+		if (res) {
+			netdev_info(hsr_dev, "Cannot set slave promiscuity (%s, %d)\n",
+				    slave[i]->name, res);
+			goto fail;
+		}
+	}
+
+	/* Make sure we recognize frames from ourselves in hsr_rcv() */
+	res = hsr_create_self_node(&hsr_priv->self_node_db,
+					hsr_dev->dev_addr,
+					hsr_priv->slave[1]->dev_addr);
+	if (res < 0)
+		goto fail;
+
+	res = register_netdevice(hsr_dev);
+	if (res)
+		goto fail;
+
+	register_hsr_master(hsr_priv);
+
+	return 0;
+
+fail:
+	restore_slaves(hsr_dev);
+	return res;
+}
diff --git a/net/hsr/hsr_device.h b/net/hsr/hsr_device.h
new file mode 100644
index 0000000..549436a
--- /dev/null
+++ b/net/hsr/hsr_device.h
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2011-2013 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2013 Arvid Brodin, [email-masked]
+ */
+
+#ifndef __HSR_DEVICE_H
+#define __HSR_DEVICE_H
+
+#include <linux/netdevice.h>
+#include "hsr_main.h"
+
+void hsr_dev_setup(struct net_device *dev);
+int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *slave[2],
+		     unsigned char multicast_spec);
+void hsr_set_operstate(struct net_device *hsr_dev, struct net_device *slave1,
+		       struct net_device *slave2);
+void hsr_set_carrier(struct net_device *hsr_dev, struct net_device *slave1,
+		     struct net_device *slave2);
+void hsr_check_announce(struct net_device *hsr_dev, int old_operstate);
+bool is_hsr_master(struct net_device *dev);
+int hsr_get_max_mtu(struct hsr_priv *hsr_priv);
+
+#endif /* __HSR_DEVICE_H */
diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c
new file mode 100644
index 0000000..51b1e53
--- /dev/null
+++ b/net/hsr/hsr_framereg.c
@@ -0,0 +1,502 @@
+/*
+ * Copyright 2011-2013 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2013 Arvid Brodin, [email-masked]
+ *
+ * The HSR spec says never to forward the same frame twice on the same
+ * interface. A frame is identified by its source MAC address and its HSR
+ * sequence number. This code keeps track of senders and their sequence numbers
+ * to allow filtering of duplicate frames, and to detect HSR ring errors.
+ */
+
+#include <linux/if_ether.h>
+#include <linux/etherdevice.h>
+#include <linux/slab.h>
+#include <linux/rculist.h>
+#include "hsr_main.h"
+#include "hsr_framereg.h"
+#include "hsr_netlink.h"
+
+
+struct node_entry {
+	struct list_head mac_list;
+	unsigned char	MacAddressA[ETH_ALEN];
+	unsigned char	MacAddressB[ETH_ALEN];
+	enum hsr_dev_idx   AddrB_if;	/* The local slave through which AddrB
+					 * frames are received from this node
+					 */
+	unsigned long	time_in[HSR_MAX_SLAVE];
+	bool		time_in_stale[HSR_MAX_SLAVE];
+	u16		seq_out[HSR_MAX_DEV];
+	struct rcu_head rcu_head;
+};
+
+/*	TODO: use hash lists for mac addresses (linux/jhash.h)?    */
+
+
+
+/* Search for mac entry. Caller must hold rcu read lock.
+ */
+static struct node_entry *find_node_by_AddrA(struct list_head *node_db,
+					     const unsigned char addr[ETH_ALEN])
+{
+	struct node_entry *node;
+
+	list_for_each_entry_rcu(node, node_db, mac_list) {
+		if (!compare_ether_addr(node->MacAddressA, addr))
+			return node;
+	}
+
+	return NULL;
+}
+
+
+/* Search for mac entry. Caller must hold rcu read lock.
+ */
+static struct node_entry *find_node_by_AddrB(struct list_head *node_db,
+					     const unsigned char addr[ETH_ALEN])
+{
+	struct node_entry *node;
+
+	list_for_each_entry_rcu(node, node_db, mac_list) {
+		if (!compare_ether_addr(node->MacAddressB, addr))
+			return node;
+	}
+
+	return NULL;
+}
+
+
+/* Search for mac entry. Caller must hold rcu read lock.
+ */
+struct node_entry *hsr_find_node(struct list_head *node_db, struct sk_buff *skb)
+{
+	struct node_entry *node;
+	struct ethhdr *ethhdr;
+
+	if (!skb_mac_header_was_set(skb))
+		return NULL;
+
+	ethhdr = (struct ethhdr *) skb_mac_header(skb);
+
+	list_for_each_entry_rcu(node, node_db, mac_list) {
+		if (!compare_ether_addr(node->MacAddressA, ethhdr->h_source))
+			return node;
+		if (!compare_ether_addr(node->MacAddressB, ethhdr->h_source))
+			return node;
+	}
+
+	return NULL;
+}
+
+
+/* Helper for device init; the self_node_db is used in hsr_rcv() to recognize
+ * frames from self that's been looped over the HSR ring.
+ */
+int hsr_create_self_node(struct list_head *self_node_db,
+			 unsigned char addr_a[ETH_ALEN],
+			 unsigned char addr_b[ETH_ALEN])
+{
+	struct node_entry *node, *oldnode;
+
+	node = kmalloc(sizeof(*node), GFP_KERNEL);
+	if (!node)
+		return -ENOMEM;
+
+	memcpy(node->MacAddressA, addr_a, ETH_ALEN);
+	memcpy(node->MacAddressB, addr_b, ETH_ALEN);
+
+	rcu_read_lock();
+	oldnode = list_first_or_null_rcu(self_node_db,
+						struct node_entry, mac_list);
+	if (oldnode) {
+		list_replace_rcu(&oldnode->mac_list, &node->mac_list);
+		rcu_read_unlock();
+		synchronize_rcu();
+		kfree(oldnode);
+	} else {
+		rcu_read_unlock();
+		list_add_tail_rcu(&node->mac_list, self_node_db);
+	}
+
+	return 0;
+}
+
+static void node_entry_reclaim(struct rcu_head *rh)
+{
+	kfree(container_of(rh, struct node_entry, rcu_head));
+}
+
+
+/* Add/merge node to the database of nodes. 'skb' must contain an HSR
+ * supervision frame.
+ * - If the supervision header's MacAddressA field is not yet in the database,
+ * this frame is from an hitherto unknown node - add it to the database.
+ * - If the sender's MAC address is not the same as its MacAddressA address,
+ * the node is using PICS_SUBS (address substitution). Record the sender's
+ * address as the node's MacAddressB.
+ *
+ * This function needs to work even if the sender node has changed one of its
+ * slaves' MAC addresses. In this case, there are four different cases described
+ * by (Addr-changed, received-from) pairs as follows. Note that changing the
+ * SlaveA address is equal to changing the node's own address:
+ *
+ * - (AddrB, SlaveB): The new AddrB will be recorded by PICS_SUBS code since
+ *		      node == NULL.
+ * - (AddrB, SlaveA): Will work as usual (the AddrB change won't be detected
+ *		      from this frame).
+ *
+ * - (AddrA, SlaveB): The old node will be found. We need to detect this and
+ *		      remove the node.
+ * - (AddrA, SlaveA): A new node will be registered (non-PICS_SUBS at first).
+ *		      The old one will be pruned after HSR_NODE_FORGET_TIME.
+ *
+ * We also need to detect if the sender's SlaveA and SlaveB cables have been
+ * swapped.
+ */
+struct node_entry *hsr_merge_node(struct hsr_priv *hsr_priv,
+				  struct node_entry *node,
+				  struct sk_buff *skb,
+				  enum hsr_dev_idx dev_idx)
+{
+	struct hsr_sup_payload *hsr_sp;
+	struct hsr_ethhdr_sp *hsr_ethsup;
+	int i;
+	unsigned long now;
+
+	hsr_ethsup = (struct hsr_ethhdr_sp *) skb_mac_header(skb);
+	hsr_sp = (struct hsr_sup_payload *) skb->data;
+
+	if (node && compare_ether_addr(node->MacAddressA, hsr_sp->MacAddressA)) {
+		/* Node has changed its AddrA, frame was received from SlaveB */
+		list_del_rcu(&node->mac_list);
+		call_rcu(&node->rcu_head, node_entry_reclaim);
+		node = NULL;
+	}
+
+	if (node && (dev_idx == node->AddrB_if) &&
+	    compare_ether_addr(node->MacAddressB, hsr_ethsup->ethhdr.h_source)) {
+		/* Cables have been swapped */
+		list_del_rcu(&node->mac_list);
+		call_rcu(&node->rcu_head, node_entry_reclaim);
+		node = NULL;
+	}
+
+	if (node && (dev_idx != node->AddrB_if) &&
+	    (node->AddrB_if != HSR_DEV_NONE) &&
+	    compare_ether_addr(node->MacAddressA, hsr_ethsup->ethhdr.h_source)) {
+		/* Cables have been swapped */
+		list_del_rcu(&node->mac_list);
+		call_rcu(&node->rcu_head, node_entry_reclaim);
+		node = NULL;
+	}
+
+	if (node)
+		return node;
+
+	node = find_node_by_AddrA(&hsr_priv->node_db, hsr_sp->MacAddressA);
+	if (node) {
+		/* Node is known, but frame was received from an unknown
+		 * address. Node is PICS_SUBS capable; merge its AddrB.
+		 */
+		memcpy(node->MacAddressB, hsr_ethsup->ethhdr.h_source, ETH_ALEN);
+		node->AddrB_if = dev_idx;
+		return node;
+	}
+
+	node = kzalloc(sizeof(*node), GFP_ATOMIC);
+	if (!node)
+		return NULL;
+
+	memcpy(node->MacAddressA, hsr_sp->MacAddressA, ETH_ALEN);
+	memcpy(node->MacAddressB, hsr_ethsup->ethhdr.h_source, ETH_ALEN);
+	if (compare_ether_addr(hsr_sp->MacAddressA, hsr_ethsup->ethhdr.h_source))
+		node->AddrB_if = dev_idx;
+	else
+		node->AddrB_if = HSR_DEV_NONE;
+
+	/* We are only interested in time diffs here, so use current jiffies
+	 * as initialization. (0 could trigger an spurious ring error warning).
+	 */
+	now = jiffies;
+	for (i = 0; i < HSR_MAX_SLAVE; i++)
+		node->time_in[i] = now;
+	for (i = 0; i < HSR_MAX_DEV; i++)
+		node->seq_out[i] = ntohs(hsr_ethsup->hsr_sup.sequence_nr) - 1;
+
+	list_add_tail_rcu(&node->mac_list, &hsr_priv->node_db);
+
+	return node;
+}
+
+
+/* 'skb' is a frame meant for this host, that is to be passed to upper layers.
+ *
+ * If the frame was sent by a node's B interface, replace the sender
+ * address with that node's "official" address (MacAddressA) so that upper
+ * layers recognize where it came from.
+ */
+void hsr_addr_subst_source(struct hsr_priv *hsr_priv, struct sk_buff *skb)
+{
+	struct ethhdr *ethhdr;
+	struct node_entry *node;
+
+	if (!skb_mac_header_was_set(skb)) {
+		WARN_ONCE(1, "%s: Mac header not set\n", __func__);
+		return;
+	}
+	ethhdr = (struct ethhdr *) skb_mac_header(skb);
+
+	rcu_read_lock();
+	node = find_node_by_AddrB(&hsr_priv->node_db, ethhdr->h_source);
+	if (node)
+		memcpy(ethhdr->h_source, node->MacAddressA, ETH_ALEN);
+	rcu_read_unlock();
+}
+
+
+/* 'skb' is a frame meant for another host.
+ * 'hsr_dev_idx' is the HSR index of the outgoing device
+ *
+ * Substitute the target (dest) MAC address if necessary, so the it matches the
+ * recipient interface MAC address, regardless of whether that is the
+ * recipient's A or B interface.
+ * This is needed to keep the packets flowing through switches that learn on
+ * which "side" the different interfaces are.
+ */
+void hsr_addr_subst_dest(struct hsr_priv *hsr_priv, struct ethhdr *ethhdr,
+			 enum hsr_dev_idx dev_idx)
+{
+	struct node_entry *node;
+
+	rcu_read_lock();
+	node = find_node_by_AddrA(&hsr_priv->node_db, ethhdr->h_dest);
+	if (node && (node->AddrB_if == dev_idx))
+		memcpy(ethhdr->h_dest, node->MacAddressB, ETH_ALEN);
+	rcu_read_unlock();
+}
+
+
+/* above(a, b) - return 1 if a > b, 0 otherwise.
+ */
+static bool above(u16 a, u16 b)
+{
+	/* Remove inconsistency where above(a, b) == below(a, b) */
+	if ((int) b - a == 32768)
+		return 0;
+
+	return (((s16) (b - a)) < 0);
+}
+#define below(a, b)		above((b), (a))
+#define above_or_eq(a, b)	(!below((a), (b)))
+#define below_or_eq(a, b)	(!above((a), (b)))
+
+
+void hsr_register_frame_in(struct node_entry *node, enum hsr_dev_idx dev_idx)
+{
+	if ((dev_idx < 0) || (dev_idx >= HSR_MAX_DEV)) {
+		WARN_ONCE(1, "%s: Invalid dev_idx (%d)\n", __func__, dev_idx);
+		return;
+	}
+	node->time_in[dev_idx] = jiffies;
+	node->time_in_stale[dev_idx] = 0;
+}
+
+
+/* 'skb' is a HSR Ethernet frame (with a HSR tag inserted), with a valid
+ * ethhdr->h_source address and skb->mac_header set.
+ *
+ * Return:
+ *	 1 if frame can be shown to have been sent recently on this interface,
+ *	 0 otherwise, or
+ *	 negative error code on error
+ */
+int hsr_register_frame_out(struct node_entry *node, enum hsr_dev_idx dev_idx,
+			   struct sk_buff *skb)
+{
+	struct hsr_ethhdr *hsr_ethhdr;
+	u16 sequence_nr;
+
+	if ((dev_idx < 0) || (dev_idx >= HSR_MAX_DEV)) {
+		WARN_ONCE(1, "%s: Invalid dev_idx (%d)\n", __func__, dev_idx);
+		return -EINVAL;
+	}
+	if (!skb_mac_header_was_set(skb)) {
+		WARN_ONCE(1, "%s: Mac header not set\n", __func__);
+		return -EINVAL;
+	}
+	hsr_ethhdr = (struct hsr_ethhdr *) skb_mac_header(skb);
+
+	sequence_nr = ntohs(hsr_ethhdr->hsr_tag.sequence_nr);
+	if (below_or_eq(sequence_nr, node->seq_out[dev_idx]))
+		return 1;
+
+	node->seq_out[dev_idx] = sequence_nr;
+	return 0;
+}
+
+
+
+static bool is_late(struct node_entry *node, enum hsr_dev_idx dev_idx)
+{
+	enum hsr_dev_idx other;
+
+	if (node->time_in_stale[dev_idx])
+		return 1;
+
+	if (dev_idx == HSR_DEV_SLAVE_A)
+		other = HSR_DEV_SLAVE_B;
+	else
+		other = HSR_DEV_SLAVE_A;
+
+	if (node->time_in_stale[other])
+		return 0;
+
+	if (time_after(node->time_in[other], node->time_in[dev_idx] +
+		       msecs_to_jiffies(MAX_SLAVE_DIFF)))
+		return 1;
+
+	return 0;
+}
+
+
+/* Remove stale sequence_nr records. Called by timer every
+ * HSR_LIFE_CHECK_INTERVAL (two seconds or so).
+ */
+void hsr_prune_nodes(struct hsr_priv *hsr_priv)
+{
+	struct node_entry *node;
+	unsigned long timestamp;
+	unsigned long time_a, time_b;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(node, &hsr_priv->node_db, mac_list) {
+		/* Shorthand */
+		time_a = node->time_in[HSR_DEV_SLAVE_A];
+		time_b = node->time_in[HSR_DEV_SLAVE_B];
+
+		/* Check for timestamps old enough to risk wrap-around */
+		if (time_after(jiffies, time_a + MAX_JIFFY_OFFSET/2))
+			node->time_in_stale[HSR_DEV_SLAVE_A] = 1;
+		if (time_after(jiffies, time_b + MAX_JIFFY_OFFSET/2))
+			node->time_in_stale[HSR_DEV_SLAVE_B] = 1;
+
+		/* Get age of newest frame from node.
+		 * At least one time_in is OK here; nodes get pruned long
+		 * before both time_ins can get stale
+		 */
+		timestamp = time_a;
+		if (node->time_in_stale[HSR_DEV_SLAVE_A] ||
+		    (!node->time_in_stale[HSR_DEV_SLAVE_B] &&
+		    time_after(time_b, time_a)))
+			timestamp = time_b;
+
+		/* Warn of ring error only as long as we get frames at all */
+		if (time_is_after_jiffies(timestamp +
+					msecs_to_jiffies(1.5*MAX_SLAVE_DIFF))) {
+
+			if (is_late(node, HSR_DEV_SLAVE_A))
+				hsr_nl_ringerror(hsr_priv, node->MacAddressA,
+						 HSR_DEV_SLAVE_A);
+			else if (is_late(node, HSR_DEV_SLAVE_B))
+				hsr_nl_ringerror(hsr_priv, node->MacAddressA,
+						 HSR_DEV_SLAVE_B);
+		}
+
+		/* Prune old entries */
+		if (time_is_before_jiffies(timestamp +
+					msecs_to_jiffies(HSR_NODE_FORGET_TIME))) {
+			hsr_nl_nodedown(hsr_priv, node->MacAddressA);
+			list_del_rcu(&node->mac_list);
+			/* Note that we need to free this entry later: */
+			call_rcu(&node->rcu_head, node_entry_reclaim);
+		}
+	}
+	rcu_read_unlock();
+}
+
+
+void *hsr_get_next_node(struct hsr_priv *hsr_priv, void *_pos,
+			unsigned char addr[ETH_ALEN])
+{
+	struct node_entry *node;
+
+	if (!_pos) {
+		node = list_first_or_null_rcu(&hsr_priv->node_db,
+						struct node_entry, mac_list);
+		if (node)
+			memcpy(addr, node->MacAddressA, ETH_ALEN);
+		return node;
+	}
+
+	node = _pos;
+	list_for_each_entry_continue_rcu(node, &hsr_priv->node_db, mac_list) {
+		memcpy(addr, node->MacAddressA, ETH_ALEN);
+		return node;
+	}
+
+	return NULL;
+}
+
+
+int hsr_get_node_data(struct hsr_priv *hsr_priv,
+		      const unsigned char *addr,
+		      unsigned char addr_b[ETH_ALEN],
+		      unsigned int *addr_b_ifindex,
+		      int *if1_age,
+		      u16 *if1_seq,
+		      int *if2_age,
+		      u16 *if2_seq)
+{
+	struct node_entry *node;
+	unsigned long tdiff;
+
+
+	rcu_read_lock();
+	node = find_node_by_AddrA(&hsr_priv->node_db, addr);
+	if (!node) {
+		rcu_read_unlock();
+		return -ENOENT;	/* No such entry */
+	}
+
+	memcpy(addr_b, node->MacAddressB, ETH_ALEN);
+
+	tdiff = jiffies - node->time_in[HSR_DEV_SLAVE_A];
+	if (node->time_in_stale[HSR_DEV_SLAVE_A])
+		*if1_age = INT_MAX;
+#if HZ <= MSEC_PER_SEC
+	else if (tdiff > msecs_to_jiffies(INT_MAX))
+		*if1_age = INT_MAX;
+#endif
+	else
+		*if1_age = jiffies_to_msecs(tdiff);
+
+	tdiff = jiffies - node->time_in[HSR_DEV_SLAVE_B];
+	if (node->time_in_stale[HSR_DEV_SLAVE_B])
+		*if2_age = INT_MAX;
+#if HZ <= MSEC_PER_SEC
+	else if (tdiff > msecs_to_jiffies(INT_MAX))
+		*if2_age = INT_MAX;
+#endif
+	else
+		*if2_age = jiffies_to_msecs(tdiff);
+
+	/* Present sequence numbers as if they were incoming on interface */
+	*if1_seq = node->seq_out[HSR_DEV_SLAVE_B];
+	*if2_seq = node->seq_out[HSR_DEV_SLAVE_A];
+
+	if ((node->AddrB_if != HSR_DEV_NONE) && hsr_priv->slave[node->AddrB_if])
+		*addr_b_ifindex = hsr_priv->slave[node->AddrB_if]->ifindex;
+	else
+		*addr_b_ifindex = -1;
+
+	rcu_read_unlock();
+
+	return 0;
+}
diff --git a/net/hsr/hsr_framereg.h b/net/hsr/hsr_framereg.h
new file mode 100644
index 0000000..0db42ca
--- /dev/null
+++ b/net/hsr/hsr_framereg.h
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2011-2013 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2013 Arvid Brodin, [email-masked]
+ */
+
+#ifndef _HSR_FRAMEREG_H
+#define _HSR_FRAMEREG_H
+
+#include "hsr_main.h"
+
+struct node_entry;
+
+struct node_entry *hsr_find_node(struct list_head *node_db, struct sk_buff *skb);
+
+struct node_entry *hsr_merge_node(struct hsr_priv *hsr_priv,
+				  struct node_entry *node,
+				  struct sk_buff *skb,
+				  enum hsr_dev_idx dev_idx);
+
+void hsr_addr_subst_source(struct hsr_priv *hsr_priv, struct sk_buff *skb);
+void hsr_addr_subst_dest(struct hsr_priv *hsr_priv, struct ethhdr *ethhdr,
+			 enum hsr_dev_idx dev_idx);
+
+void hsr_register_frame_in(struct node_entry *node, enum hsr_dev_idx dev_idx);
+
+int hsr_register_frame_out(struct node_entry *node, enum hsr_dev_idx dev_idx,
+			   struct sk_buff *skb);
+
+void hsr_prune_nodes(struct hsr_priv *hsr_priv);
+
+int hsr_create_self_node(struct list_head *self_node_db,
+			 unsigned char addr_a[ETH_ALEN],
+			 unsigned char addr_b[ETH_ALEN]);
+
+void *hsr_get_next_node(struct hsr_priv *hsr_priv, void *_pos,
+			unsigned char addr[ETH_ALEN]);
+
+int hsr_get_node_data(struct hsr_priv *hsr_priv,
+		      const unsigned char *addr,
+		      unsigned char addr_b[ETH_ALEN],
+		      unsigned int *addr_b_ifindex,
+		      int *if1_age,
+		      u16 *if1_seq,
+		      int *if2_age,
+		      u16 *if2_seq);
+
+#endif /* _HSR_FRAMEREG_H */
diff --git a/net/hsr/hsr_main.c b/net/hsr/hsr_main.c
new file mode 100644
index 0000000..ebca843
--- /dev/null
+++ b/net/hsr/hsr_main.c
@@ -0,0 +1,457 @@
+/*
+ * Copyright 2011-2013 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2013 Arvid Brodin, [email-masked]
+ *
+ * In addition to routines for registering and unregistering HSR support, this
+ * file also contains the receive routine that handles all incoming frames with
+ * Ethertype (protocol) ETH_P_PRP (HSRv0), and network device event handling.
+ */
+
+#include <linux/netdevice.h>
+#include <linux/rculist.h>
+#include <linux/timer.h>
+#include <linux/etherdevice.h>
+#include "hsr_main.h"
+#include "hsr_device.h"
+#include "hsr_netlink.h"
+#include "hsr_framereg.h"
+
+
+/* List of all registered virtual HSR devices */
+static LIST_HEAD(hsr_list);
+
+void register_hsr_master(struct hsr_priv *hsr_priv)
+{
+	list_add_tail_rcu(&hsr_priv->hsr_list, &hsr_list);
+}
+
+void unregister_hsr_master(struct hsr_priv *hsr_priv)
+{
+	struct hsr_priv *hsr_priv_it;
+
+	list_for_each_entry(hsr_priv_it, &hsr_list, hsr_list)
+		if (hsr_priv_it == hsr_priv) {
+			list_del_rcu(&hsr_priv_it->hsr_list);
+			return;
+		}
+}
+
+bool is_hsr_slave(struct net_device *dev)
+{
+	struct hsr_priv *hsr_priv_it;
+
+	list_for_each_entry_rcu(hsr_priv_it, &hsr_list, hsr_list) {
+		if (dev == hsr_priv_it->slave[0])
+			return true;
+		if (dev == hsr_priv_it->slave[1])
+			return true;
+	}
+
+	return false;
+}
+
+
+/* If dev is a HSR slave device, return the virtual master device. Return NULL
+ * otherwise.
+ */
+static struct hsr_priv *get_hsr_master(struct net_device *dev)
+{
+	struct hsr_priv *hsr_priv;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(hsr_priv, &hsr_list, hsr_list)
+		if ((dev == hsr_priv->slave[0]) ||
+		    (dev == hsr_priv->slave[1])) {
+			rcu_read_unlock();
+			return hsr_priv;
+		}
+
+	rcu_read_unlock();
+	return NULL;
+}
+
+
+/* If dev is a HSR slave device, return the other slave device. Return NULL
+ * otherwise.
+ */
+static struct net_device *get_other_slave(struct hsr_priv *hsr_priv,
+					  struct net_device *dev)
+{
+	if (dev == hsr_priv->slave[0])
+		return hsr_priv->slave[1];
+	if (dev == hsr_priv->slave[1])
+		return hsr_priv->slave[0];
+
+	return NULL;
+}
+
+
+static int hsr_netdev_notify(struct notifier_block *nb, unsigned long event,
+			     void *ptr)
+{
+	struct net_device *slave, *other_slave;
+	struct hsr_priv *hsr_priv;
+	int old_operstate;
+	int mtu_max;
+	int res;
+	struct net_device *dev;
+
+	dev = netdev_notifier_info_to_dev(ptr);
+
+	hsr_priv = get_hsr_master(dev);
+	if (hsr_priv) {
+		/* dev is a slave device */
+		slave = dev;
+		other_slave = get_other_slave(hsr_priv, slave);
+	} else {
+		if (!is_hsr_master(dev))
+			return NOTIFY_DONE;
+		hsr_priv = netdev_priv(dev);
+		slave = hsr_priv->slave[0];
+		other_slave = hsr_priv->slave[1];
+	}
+
+	switch (event) {
+	case NETDEV_UP:		/* Administrative state DOWN */
+	case NETDEV_DOWN:	/* Administrative state UP */
+	case NETDEV_CHANGE:	/* Link (carrier) state changes */
+		old_operstate = hsr_priv->dev->operstate;
+		hsr_set_carrier(hsr_priv->dev, slave, other_slave);
+		/* netif_stacked_transfer_operstate() cannot be used here since
+		 * it doesn't set IF_OPER_LOWERLAYERDOWN (?)
+		 */
+		hsr_set_operstate(hsr_priv->dev, slave, other_slave);
+		hsr_check_announce(hsr_priv->dev, old_operstate);
+		break;
+	case NETDEV_CHANGEADDR:
+		/* This should not happen since there's no ndo_set_mac_address()
+		 * for HSR devices - i.e. not supported.
+		 */
+		if (dev == hsr_priv->dev)
+			break;
+		if (dev == hsr_priv->slave[0])
+			memcpy(hsr_priv->dev->dev_addr,
+			       hsr_priv->slave[0]->dev_addr, ETH_ALEN);
+
+		/* Make sure we recognize frames from ourselves in hsr_rcv() */
+		res = hsr_create_self_node(&hsr_priv->self_node_db,
+					   hsr_priv->dev->dev_addr,
+					   hsr_priv->slave[1] ?
+						hsr_priv->slave[1]->dev_addr :
+						hsr_priv->dev->dev_addr);
+		if (res)
+			netdev_warn(hsr_priv->dev,
+				    "Could not update HSR node address.\n");
+
+		if (dev == hsr_priv->slave[0])
+			call_netdevice_notifiers(NETDEV_CHANGEADDR, hsr_priv->dev);
+		break;
+	case NETDEV_CHANGEMTU:
+		if (dev == hsr_priv->dev)
+			break; /* Handled in ndo_change_mtu() */
+		mtu_max = hsr_get_max_mtu(hsr_priv);
+		if (hsr_priv->dev->mtu > mtu_max)
+			dev_set_mtu(hsr_priv->dev, mtu_max);
+		break;
+	case NETDEV_UNREGISTER:
+		if (dev == hsr_priv->slave[0])
+			hsr_priv->slave[0] = NULL;
+		if (dev == hsr_priv->slave[1])
+			hsr_priv->slave[1] = NULL;
+
+		/* There should really be a way to set a new slave device... */
+
+		break;
+	case NETDEV_PRE_TYPE_CHANGE:
+		/* HSR works only on Ethernet devices. Refuse slave to change
+		 * its type.
+		 */
+		return NOTIFY_BAD;
+	}
+
+	return NOTIFY_DONE;
+}
+
+
+static struct timer_list prune_timer;
+
+static void prune_nodes_all(unsigned long data)
+{
+	struct hsr_priv *hsr_priv;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(hsr_priv, &hsr_list, hsr_list)
+		hsr_prune_nodes(hsr_priv);
+	rcu_read_unlock();
+
+	prune_timer.expires = jiffies + msecs_to_jiffies(PRUNE_PERIOD);
+	add_timer(&prune_timer);
+}
+
+
+static struct sk_buff *strip_hsr_tag(struct sk_buff *skb)
+{
+	struct hsr_tag *hsr_tag;
+	struct sk_buff *skb2;
+
+	skb2 = skb_share_check(skb, GFP_ATOMIC);
+	if (unlikely(!skb2))
+		goto err_free;
+	skb = skb2;
+
+	if (unlikely(!pskb_may_pull(skb, HSR_TAGLEN)))
+		goto err_free;
+
+	hsr_tag = (struct hsr_tag *) skb->data;
+	skb->protocol = hsr_tag->encap_proto;
+	skb_pull(skb, HSR_TAGLEN);
+
+	return skb;
+
+err_free:
+	kfree_skb(skb);
+	return NULL;
+}
+
+
+/* The uses I can see for these HSR supervision frames are:
+ * 1) Use the frames that are sent after node initialization ("HSR_TLV.Type =
+ *    22") to reset any sequence_nr counters belonging to that node. Useful if
+ *    the other node's counter has been reset for some reason.
+ *    --
+ *    Or not - resetting the counter and bridging the frame would create a
+ *    loop, unfortunately.
+ *
+ * 2) Use the LifeCheck frames to detect ring breaks. I.e. if no LifeCheck
+ *    frame is received from a particular node, we know something is wrong.
+ *    We just register these (as with normal frames) and throw them away.
+ *
+ * 3) Allow different MAC addresses for the two slave interfaces, using the
+ *    MacAddressA field.
+ */
+static bool is_supervision_frame(struct hsr_priv *hsr_priv, struct sk_buff *skb)
+{
+	struct hsr_sup_tag *hsr_stag;
+
+	if (compare_ether_addr(eth_hdr(skb)->h_dest,
+			       hsr_priv->sup_multicast_addr))
+		return 0;
+
+	hsr_stag = (struct hsr_sup_tag *) skb->data;
+	if (get_hsr_stag_path(hsr_stag) != 0x0f)
+		return 0;
+	if ((hsr_stag->HSR_TLV_Type != HSR_TLV_ANNOUNCE) &&
+	    (hsr_stag->HSR_TLV_Type != HSR_TLV_LIFE_CHECK))
+		return 0;
+	if (hsr_stag->HSR_TLV_Length != 12)
+		return 0;
+
+	return 1;
+}
+
+
+/* Implementation somewhat according to IEC-62439-3, p. 43
+ */
+static int hsr_rcv(struct sk_buff *skb, struct net_device *dev,
+		   struct packet_type *pt, struct net_device *orig_dev)
+{
+	struct hsr_priv *hsr_priv;
+	struct net_device *other_slave;
+	struct node_entry *node;
+	int deliver_to_self;
+	struct sk_buff *skb_deliver;
+	enum hsr_dev_idx dev_in_idx, dev_other_idx;
+	bool dup_out;
+	int ret;
+
+	hsr_priv = get_hsr_master(dev);
+
+	if (!hsr_priv) {
+		/* Non-HSR-slave device 'dev' is connected to a HSR network */
+		kfree_skb(skb);
+		dev->stats.rx_errors++;
+		return NET_RX_SUCCESS;
+	}
+
+	if (dev == hsr_priv->slave[0]) {
+		dev_in_idx = HSR_DEV_SLAVE_A;
+		dev_other_idx = HSR_DEV_SLAVE_B;
+	} else {
+		dev_in_idx = HSR_DEV_SLAVE_B;
+		dev_other_idx = HSR_DEV_SLAVE_A;
+	}
+
+	node = hsr_find_node(&hsr_priv->self_node_db, skb);
+	if (node) {
+		/* Always kill frames sent by ourselves */
+		kfree_skb(skb);
+		return NET_RX_SUCCESS;
+	}
+
+	/* Is this frame a candidate for local reception? */
+	deliver_to_self = 0;
+	if ((skb->pkt_type == PACKET_HOST) ||
+	    (skb->pkt_type == PACKET_MULTICAST) ||
+	    (skb->pkt_type == PACKET_BROADCAST))
+		deliver_to_self = 1;
+	else if (!compare_ether_addr(eth_hdr(skb)->h_dest,
+				     hsr_priv->dev->dev_addr)) {
+		skb->pkt_type = PACKET_HOST;
+		deliver_to_self = 1;
+	}
+
+
+	rcu_read_lock(); /* node_db */
+	node = hsr_find_node(&hsr_priv->node_db, skb);
+
+	if (is_supervision_frame(hsr_priv, skb)) {
+		skb_pull(skb, sizeof(struct hsr_sup_tag));
+		node = hsr_merge_node(hsr_priv, node, skb, dev_in_idx);
+		if (!node) {
+			rcu_read_unlock(); /* node_db */
+			kfree_skb(skb);
+			hsr_priv->dev->stats.rx_dropped++;
+			return NET_RX_DROP;
+		}
+		skb_push(skb, sizeof(struct hsr_sup_tag));
+		deliver_to_self = 0;
+	}
+
+	if (!node) {
+		/* Source node unknown; this might be a HSR frame from
+		 * another net (different multicast address). Ignore it.
+		 */
+		rcu_read_unlock(); /* node_db */
+		kfree_skb(skb);
+		return NET_RX_SUCCESS;
+	}
+
+	/* Register ALL incoming frames as outgoing through the other interface.
+	 * This allows us to register frames as incoming only if they are valid
+	 * for the receiving interface, without using a specific counter for
+	 * incoming frames.
+	 */
+	dup_out = hsr_register_frame_out(node, dev_other_idx, skb);
+	if (!dup_out)
+		hsr_register_frame_in(node, dev_in_idx);
+
+	/* Forward this frame? */
+	if (!dup_out && (skb->pkt_type != PACKET_HOST))
+		other_slave = get_other_slave(hsr_priv, dev);
+	else
+		other_slave = NULL;
+
+	if (hsr_register_frame_out(node, HSR_DEV_MASTER, skb))
+		deliver_to_self = 0;
+
+	rcu_read_unlock(); /* node_db */
+
+	if (!deliver_to_self && !other_slave) {
+		kfree_skb(skb);
+		/* Circulated frame; silently remove it. */
+		return NET_RX_SUCCESS;
+	}
+
+	skb_deliver = skb;
+	if (deliver_to_self && other_slave) {
+		/* skb_clone() is not enough since we will strip the hsr tag
+		 * and do address substitution below
+		 */
+		skb_deliver = pskb_copy(skb, GFP_ATOMIC);
+		if (!skb_deliver) {
+			deliver_to_self = 0;
+			hsr_priv->dev->stats.rx_dropped++;
+		}
+	}
+
+	if (deliver_to_self) {
+		bool multicast_frame;
+
+		skb_deliver = strip_hsr_tag(skb_deliver);
+		if (!skb_deliver) {
+			hsr_priv->dev->stats.rx_dropped++;
+			goto forward;
+		}
+#if !defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
+		/* We need to memmove the whole header to work around
+		 * alignment problems caused by the 6-byte HSR tag.
+		 */
+		memmove(skb_deliver->data - HSR_TAGLEN, skb_deliver->data,
+			skb_headlen(skb_deliver));
+		skb_deliver->data -= HSR_TAGLEN;
+		skb_deliver->tail -= HSR_TAGLEN;
+#endif
+		skb_deliver->dev = hsr_priv->dev;
+		hsr_addr_subst_source(hsr_priv, skb_deliver);
+		multicast_frame = (skb_deliver->pkt_type == PACKET_MULTICAST);
+		ret = netif_rx(skb_deliver);
+		if (ret == NET_RX_DROP) {
+			hsr_priv->dev->stats.rx_dropped++;
+		} else {
+			hsr_priv->dev->stats.rx_packets++;
+			hsr_priv->dev->stats.rx_bytes += skb->len;
+			if (multicast_frame)
+				hsr_priv->dev->stats.multicast++;
+		}
+	}
+
+forward:
+	if (other_slave) {
+		skb_push(skb, ETH_HLEN);
+		skb->dev = other_slave;
+		dev_queue_xmit(skb);
+	}
+
+	return NET_RX_SUCCESS;
+}
+
+
+static struct packet_type hsr_pt __read_mostly = {
+	.type = htons(ETH_P_PRP),
+	.func = hsr_rcv,
+};
+
+static struct notifier_block hsr_nb = {
+	.notifier_call = hsr_netdev_notify,	/* Slave event notifications */
+};
+
+
+static int __init hsr_init(void)
+{
+	int res;
+
+	BUILD_BUG_ON(sizeof(struct hsr_tag) != HSR_TAGLEN);
+
+	dev_add_pack(&hsr_pt);
+
+	init_timer(&prune_timer);
+	prune_timer.function = prune_nodes_all;
+	prune_timer.data = 0;
+	prune_timer.expires = jiffies + msecs_to_jiffies(PRUNE_PERIOD);
+	add_timer(&prune_timer);
+
+	register_netdevice_notifier(&hsr_nb);
+
+	res = hsr_netlink_init();
+
+	return res;
+}
+
+static void __exit hsr_exit(void)
+{
+	unregister_netdevice_notifier(&hsr_nb);
+	del_timer(&prune_timer);
+	hsr_netlink_exit();
+	dev_remove_pack(&hsr_pt);
+}
+
+module_init(hsr_init);
+module_exit(hsr_exit);
+MODULE_LICENSE("GPL");
diff --git a/net/hsr/hsr_main.h b/net/hsr/hsr_main.h
new file mode 100644
index 0000000..c1fcfba
--- /dev/null
+++ b/net/hsr/hsr_main.h
@@ -0,0 +1,167 @@
+/*
+ * Copyright 2011-2013 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2013 Arvid Brodin, [email-masked]
+ */
+
+#ifndef _HSR_PRIVATE_H
+#define _HSR_PRIVATE_H
+
+#include <linux/netdevice.h>
+#include <linux/list.h>
+
+
+/* Time constants as specified in the HSR specification (IEC-62439-3 2010)
+ * Table 8.
+ * All values in milliseconds.
+ */
+#define HSR_LIFE_CHECK_INTERVAL		 2000 /* ms */
+#define HSR_NODE_FORGET_TIME		60000 /* ms */
+#define HSR_ANNOUNCE_INTERVAL		  100 /* ms */
+
+
+/* By how much may slave1 and slave2 timestamps of latest received frame from
+ * each node differ before we notify of communication problem?
+ */
+#define MAX_SLAVE_DIFF			 3000 /* ms */
+
+
+/* How often shall we check for broken ring and remove node entries older than
+ * HSR_NODE_FORGET_TIME?
+ */
+#define PRUNE_PERIOD			 3000 /* ms */
+
+
+#define HSR_TLV_ANNOUNCE		   22
+#define HSR_TLV_LIFE_CHECK		   23
+
+
+/* HSR Tag.
+ * As defined in IEC-62439-3:2010, the HSR tag is really { ethertype = 0x88FB,
+ * path, LSDU_size, sequence Nr }. But we let eth_header() create { h_dest,
+ * h_source, h_proto = 0x88FB }, and add { path, LSDU_size, sequence Nr,
+ * encapsulated protocol } instead.
+ */
+#define HSR_TAGLEN	6
+
+/* Field names below as defined in the IEC:2010 standard for HSR. */
+struct hsr_tag {
+	__be16		path_and_LSDU_size;
+	__be16		sequence_nr;
+	__be16		encap_proto;
+} __packed;
+
+
+/* The helper functions below assumes that 'path' occupies the 4 most
+ * significant bits of the 16-bit field shared by 'path' and 'LSDU_size' (or
+ * equivalently, the 4 most significant bits of HSR tag byte 14).
+ *
+ * This is unclear in the IEC specification; its definition of MAC addresses
+ * indicates the spec is written with the least significant bit first (to the
+ * left). This, however, would mean that the LSDU field would be split in two
+ * with the path field in-between, which seems strange. I'm guessing the MAC
+ * address definition is in error.
+ */
+static inline u16 get_hsr_tag_path(struct hsr_tag *ht)
+{
+	return ntohs(ht->path_and_LSDU_size) >> 12;
+}
+
+static inline u16 get_hsr_tag_LSDU_size(struct hsr_tag *ht)
+{
+	return ntohs(ht->path_and_LSDU_size) & 0x0FFF;
+}
+
+static inline void set_hsr_tag_path(struct hsr_tag *ht, u16 path)
+{
+	ht->path_and_LSDU_size = htons(
+			(ntohs(ht->path_and_LSDU_size) & 0x0FFF) | (path << 12));
+}
+
+static inline void set_hsr_tag_LSDU_size(struct hsr_tag *ht, u16 LSDU_size)
+{
+	ht->path_and_LSDU_size = htons(
+			(ntohs(ht->path_and_LSDU_size) & 0xF000) |
+			(LSDU_size & 0x0FFF));
+}
+
+struct hsr_ethhdr {
+	struct ethhdr	ethhdr;
+	struct hsr_tag	hsr_tag;
+} __packed;
+
+
+/* HSR Supervision Frame data types.
+ * Field names as defined in the IEC:2010 standard for HSR.
+ */
+struct hsr_sup_tag {
+	__be16		path_and_HSR_Ver;
+	__be16		sequence_nr;
+	__u8		HSR_TLV_Type;
+	__u8		HSR_TLV_Length;
+} __packed;
+
+struct hsr_sup_payload {
+	unsigned char	MacAddressA[ETH_ALEN];
+} __packed;
+
+static inline u16 get_hsr_stag_path(struct hsr_sup_tag *hst)
+{
+	return get_hsr_tag_path((struct hsr_tag *) hst);
+}
+
+static inline u16 get_hsr_stag_HSR_ver(struct hsr_sup_tag *hst)
+{
+	return get_hsr_tag_LSDU_size((struct hsr_tag *) hst);
+}
+
+static inline void set_hsr_stag_path(struct hsr_sup_tag *hst, u16 path)
+{
+	set_hsr_tag_path((struct hsr_tag *) hst, path);
+}
+
+static inline void set_hsr_stag_HSR_Ver(struct hsr_sup_tag *hst, u16 HSR_Ver)
+{
+	set_hsr_tag_LSDU_size((struct hsr_tag *) hst, HSR_Ver);
+}
+
+struct hsr_ethhdr_sp {
+	struct ethhdr		ethhdr;
+	struct hsr_sup_tag	hsr_sup;
+} __packed;
+
+
+enum hsr_dev_idx {
+	HSR_DEV_NONE = -1,
+	HSR_DEV_SLAVE_A = 0,
+	HSR_DEV_SLAVE_B,
+	HSR_DEV_MASTER,
+};
+#define HSR_MAX_SLAVE	(HSR_DEV_SLAVE_B + 1)
+#define HSR_MAX_DEV	(HSR_DEV_MASTER + 1)
+
+struct hsr_priv {
+	struct list_head	hsr_list;	/* List of hsr devices */
+	struct rcu_head		rcu_head;
+	struct net_device	*dev;
+	struct net_device	*slave[HSR_MAX_SLAVE];
+	struct list_head	node_db;	/* Other HSR nodes */
+	struct list_head	self_node_db;	/* MACs of slaves */
+	struct timer_list	announce_timer;	/* Supervision frame dispatch */
+	int announce_count;
+	u16 sequence_nr;
+	spinlock_t seqnr_lock;			/* locking for sequence_nr */
+	unsigned char		sup_multicast_addr[ETH_ALEN];
+};
+
+void register_hsr_master(struct hsr_priv *hsr_priv);
+void unregister_hsr_master(struct hsr_priv *hsr_priv);
+bool is_hsr_slave(struct net_device *dev);
+
+#endif /*  _HSR_PRIVATE_H */
diff --git a/net/hsr/hsr_netlink.c b/net/hsr/hsr_netlink.c
new file mode 100644
index 0000000..7ac0392
--- /dev/null
+++ b/net/hsr/hsr_netlink.c
@@ -0,0 +1,458 @@
+/*
+ * Copyright 2011-2013 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2013 Arvid Brodin, [email-masked]
+ *
+ * Routines for handling Netlink messages for HSR.
+ */
+
+#include "hsr_netlink.h"
+#include <linux/kernel.h>
+#include <net/rtnetlink.h>
+#include <net/genetlink.h>
+#include "hsr_main.h"
+#include "hsr_device.h"
+#include "hsr_framereg.h"
+
+static const struct nla_policy hsr_policy[IFLA_HSR_MAX + 1] = {
+	[IFLA_HSR_SLAVE1]		= { .type = NLA_U32 },
+	[IFLA_HSR_SLAVE2]		= { .type = NLA_U32 },
+	[IFLA_HSR_MULTICAST_SPEC]	= { .type = NLA_U8 },
+};
+
+
+/* Here, it seems a netdevice has already been allocated for us, and the
+ * hsr_dev_setup routine has been executed. Nice!
+ */
+static int hsr_newlink(struct net *src_net, struct net_device *dev,
+		       struct nlattr *tb[], struct nlattr *data[])
+{
+	struct net_device *link[2];
+	unsigned char multicast_spec;
+
+	if (!data[IFLA_HSR_SLAVE1]) {
+		netdev_info(dev, "IFLA_HSR_SLAVE1 missing!\n");
+		return -EINVAL;
+	}
+	link[0] = __dev_get_by_index(src_net, nla_get_u32(data[IFLA_HSR_SLAVE1]));
+	if (!data[IFLA_HSR_SLAVE2]) {
+		netdev_info(dev, "IFLA_HSR_SLAVE2 missing!\n");
+		return -EINVAL;
+	}
+	link[1] = __dev_get_by_index(src_net, nla_get_u32(data[IFLA_HSR_SLAVE2]));
+
+	if (!link[0] || !link[1])
+		return -ENODEV;
+	if (link[0] == link[1])
+		return -EINVAL;
+
+	if (!data[IFLA_HSR_MULTICAST_SPEC])
+		multicast_spec = 0;
+	else
+		multicast_spec = nla_get_u8(data[IFLA_HSR_MULTICAST_SPEC]);
+
+	return hsr_dev_finalize(dev, link, multicast_spec);
+}
+
+static struct rtnl_link_ops hsr_link_ops __read_mostly = {
+	.kind		= "hsr",
+	.maxtype	= IFLA_HSR_MAX,
+	.policy		= hsr_policy,
+	.priv_size	= sizeof(struct hsr_priv),
+	.setup		= hsr_dev_setup,
+	.newlink	= hsr_newlink,
+};
+
+
+
+/* attribute policy */
+/* NLA_BINARY missing in libnl; use NLA_UNSPEC in userspace instead. */
+static const struct nla_policy hsr_genl_policy[HSR_A_MAX + 1] = {
+	[HSR_A_NODE_ADDR] = { .type = NLA_BINARY, .len = ETH_ALEN },
+	[HSR_A_NODE_ADDR_B] = { .type = NLA_BINARY, .len = ETH_ALEN },
+	[HSR_A_IFINDEX] = { .type = NLA_U32 },
+	[HSR_A_IF1_AGE] = { .type = NLA_U32 },
+	[HSR_A_IF2_AGE] = { .type = NLA_U32 },
+	[HSR_A_IF1_SEQ] = { .type = NLA_U16 },
+	[HSR_A_IF2_SEQ] = { .type = NLA_U16 },
+};
+
+static struct genl_family hsr_genl_family = {
+	.id = GENL_ID_GENERATE,
+	.hdrsize = 0,
+	.name = "HSR",
+	.version = 1,
+	.maxattr = HSR_A_MAX,
+};
+
+static struct genl_multicast_group hsr_network_genl_mcgrp = {
+	.name = "hsr-network",
+};
+
+
+
+/* This is called if for some node with MAC address addr, we only get frames
+ * over one of the slave interfaces. This would indicate an open network ring
+ * (i.e. a link has failed somewhere).
+ */
+void hsr_nl_ringerror(struct hsr_priv *hsr_priv, unsigned char addr[ETH_ALEN],
+		      enum hsr_dev_idx dev_idx)
+{
+	struct sk_buff *skb;
+	void *msg_head;
+	int res;
+	int ifindex;
+
+	skb = genlmsg_new(NLMSG_GOODSIZE, GFP_ATOMIC);
+	if (!skb)
+		goto fail;
+
+	msg_head = genlmsg_put(skb, 0, 0, &hsr_genl_family, 0, HSR_C_RING_ERROR);
+	if (!msg_head)
+		goto nla_put_failure;
+
+	res = nla_put(skb, HSR_A_NODE_ADDR, ETH_ALEN, addr);
+	if (res < 0)
+		goto nla_put_failure;
+
+	if (hsr_priv->slave[dev_idx])
+		ifindex = hsr_priv->slave[dev_idx]->ifindex;
+	else
+		ifindex = -1;
+	res = nla_put_u32(skb, HSR_A_IFINDEX, ifindex);
+	if (res < 0)
+		goto nla_put_failure;
+
+	genlmsg_end(skb, msg_head);
+	genlmsg_multicast(skb, 0, hsr_network_genl_mcgrp.id, GFP_ATOMIC);
+
+	return;
+
+nla_put_failure:
+	kfree_skb(skb);
+
+fail:
+	netdev_warn(hsr_priv->dev, "Could not send HSR ring error message\n");
+}
+
+/* This is called when we haven't heard from the node with MAC address addr for
+ * some time (just before the node is removed from the node table/list).
+ */
+void hsr_nl_nodedown(struct hsr_priv *hsr_priv, unsigned char addr[ETH_ALEN])
+{
+	struct sk_buff *skb;
+	void *msg_head;
+	int res;
+
+	skb = genlmsg_new(NLMSG_GOODSIZE, GFP_ATOMIC);
+	if (!skb)
+		goto fail;
+
+	msg_head = genlmsg_put(skb, 0, 0, &hsr_genl_family, 0, HSR_C_NODE_DOWN);
+	if (!msg_head)
+		goto nla_put_failure;
+
+
+	res = nla_put(skb, HSR_A_NODE_ADDR, ETH_ALEN, addr);
+	if (res < 0)
+		goto nla_put_failure;
+
+	genlmsg_end(skb, msg_head);
+	genlmsg_multicast(skb, 0, hsr_network_genl_mcgrp.id, GFP_ATOMIC);
+
+	return;
+
+nla_put_failure:
+	kfree_skb(skb);
+
+fail:
+	netdev_warn(hsr_priv->dev, "Could not send HSR node down\n");
+}
+
+
+/* HSR_C_GET_NODE_STATUS lets userspace query the internal HSR node table
+ * about the status of a specific node in the network, defined by its MAC
+ * address.
+ *
+ * Input: hsr ifindex, node mac address
+ * Output: hsr ifindex, node mac address (copied from request),
+ *	   age of latest frame from node over slave 1, slave 2 [ms]
+ */
+static int hsr_get_node_status(struct sk_buff *skb_in, struct genl_info *info)
+{
+	/* For receiving */
+	struct nlattr *na;
+	struct net_device *hsr_dev;
+
+	/* For sending */
+	struct sk_buff *skb_out;
+	void *msg_head;
+	struct hsr_priv *hsr_priv;
+	unsigned char hsr_node_addr_b[ETH_ALEN];
+	int hsr_node_if1_age;
+	u16 hsr_node_if1_seq;
+	int hsr_node_if2_age;
+	u16 hsr_node_if2_seq;
+	int addr_b_ifindex;
+	int res;
+
+	if (!info)
+		goto invalid;
+
+	na = info->attrs[HSR_A_IFINDEX];
+	if (!na)
+		goto invalid;
+	na = info->attrs[HSR_A_NODE_ADDR];
+	if (!na)
+		goto invalid;
+
+	hsr_dev = __dev_get_by_index(genl_info_net(info),
+					nla_get_u32(info->attrs[HSR_A_IFINDEX]));
+	if (!hsr_dev)
+		goto invalid;
+	if (!is_hsr_master(hsr_dev))
+		goto invalid;
+
+
+	/* Send reply */
+
+	skb_out = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
+	if (!skb_out) {
+		res = -ENOMEM;
+		goto fail;
+	}
+
+	msg_head = genlmsg_put(skb_out, NETLINK_CB(skb_in).portid,
+				info->snd_seq, &hsr_genl_family, 0,
+				HSR_C_SET_NODE_STATUS);
+	if (!msg_head) {
+		res = -ENOMEM;
+		goto nla_put_failure;
+	}
+
+	res = nla_put_u32(skb_out, HSR_A_IFINDEX, hsr_dev->ifindex);
+	if (res < 0)
+		goto nla_put_failure;
+
+	hsr_priv = netdev_priv(hsr_dev);
+	res = hsr_get_node_data(hsr_priv,
+			(unsigned char *) nla_data(info->attrs[HSR_A_NODE_ADDR]),
+			hsr_node_addr_b,
+			&addr_b_ifindex,
+			&hsr_node_if1_age,
+			&hsr_node_if1_seq,
+			&hsr_node_if2_age,
+			&hsr_node_if2_seq);
+	if (res < 0)
+		goto fail;
+
+	res = nla_put(skb_out, HSR_A_NODE_ADDR, ETH_ALEN,
+					nla_data(info->attrs[HSR_A_NODE_ADDR]));
+	if (res < 0)
+		goto nla_put_failure;
+
+	if (addr_b_ifindex > -1) {
+		res = nla_put(skb_out, HSR_A_NODE_ADDR_B, ETH_ALEN,
+								hsr_node_addr_b);
+		if (res < 0)
+			goto nla_put_failure;
+
+		res = nla_put_u32(skb_out, HSR_A_ADDR_B_IFINDEX, addr_b_ifindex);
+		if (res < 0)
+			goto nla_put_failure;
+	}
+
+	res = nla_put_u32(skb_out, HSR_A_IF1_AGE, hsr_node_if1_age);
+	if (res < 0)
+		goto nla_put_failure;
+	res = nla_put_u16(skb_out, HSR_A_IF1_SEQ, hsr_node_if1_seq);
+	if (res < 0)
+		goto nla_put_failure;
+	if (hsr_priv->slave[0])
+		res = nla_put_u32(skb_out, HSR_A_IF1_IFINDEX,
+						hsr_priv->slave[0]->ifindex);
+	if (res < 0)
+		goto nla_put_failure;
+
+	res = nla_put_u32(skb_out, HSR_A_IF2_AGE, hsr_node_if2_age);
+	if (res < 0)
+		goto nla_put_failure;
+	res = nla_put_u16(skb_out, HSR_A_IF2_SEQ, hsr_node_if2_seq);
+	if (res < 0)
+		goto nla_put_failure;
+	if (hsr_priv->slave[1])
+		res = nla_put_u32(skb_out, HSR_A_IF2_IFINDEX,
+						hsr_priv->slave[1]->ifindex);
+
+	genlmsg_end(skb_out, msg_head);
+	genlmsg_unicast(genl_info_net(info), skb_out, info->snd_portid);
+
+	return 0;
+
+invalid:
+	netlink_ack(skb_in, nlmsg_hdr(skb_in), -EINVAL);
+	return 0;
+
+nla_put_failure:
+	kfree_skb(skb_out);
+	/* Fall through */
+
+fail:
+	return res;
+}
+
+static struct genl_ops hsr_ops_get_node_status = {
+	.cmd = HSR_C_GET_NODE_STATUS,
+	.flags = 0,
+	.policy = hsr_genl_policy,
+	.doit = hsr_get_node_status,
+	.dumpit = NULL,
+};
+
+
+/* Get a list of MacAddressA of all nodes known to this node (other than self).
+ */
+static int hsr_get_node_list(struct sk_buff *skb_in, struct genl_info *info)
+{
+	/* For receiving */
+	struct nlattr *na;
+	struct net_device *hsr_dev;
+
+	/* For sending */
+	struct sk_buff *skb_out;
+	void *msg_head;
+	struct hsr_priv *hsr_priv;
+	void *pos;
+	unsigned char addr[ETH_ALEN];
+	int res;
+
+	if (!info)
+		goto invalid;
+
+	na = info->attrs[HSR_A_IFINDEX];
+	if (!na)
+		goto invalid;
+
+	hsr_dev = __dev_get_by_index(genl_info_net(info),
+				     nla_get_u32(info->attrs[HSR_A_IFINDEX]));
+	if (!hsr_dev)
+		goto invalid;
+	if (!is_hsr_master(hsr_dev))
+		goto invalid;
+
+
+	/* Send reply */
+
+	skb_out = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
+	if (!skb_out) {
+		res = -ENOMEM;
+		goto fail;
+	}
+
+	msg_head = genlmsg_put(skb_out, NETLINK_CB(skb_in).portid,
+				info->snd_seq, &hsr_genl_family, 0,
+				HSR_C_SET_NODE_LIST);
+	if (!msg_head) {
+		res = -ENOMEM;
+		goto nla_put_failure;
+	}
+
+	res = nla_put_u32(skb_out, HSR_A_IFINDEX, hsr_dev->ifindex);
+	if (res < 0)
+		goto nla_put_failure;
+
+	hsr_priv = netdev_priv(hsr_dev);
+
+	rcu_read_lock();
+	pos = hsr_get_next_node(hsr_priv, NULL, addr);
+	while (pos) {
+		res = nla_put(skb_out, HSR_A_NODE_ADDR, ETH_ALEN, addr);
+		if (res < 0) {
+			rcu_read_unlock();
+			goto nla_put_failure;
+		}
+		pos = hsr_get_next_node(hsr_priv, pos, addr);
+	}
+	rcu_read_unlock();
+
+	genlmsg_end(skb_out, msg_head);
+	genlmsg_unicast(genl_info_net(info), skb_out, info->snd_portid);
+
+	return 0;
+
+invalid:
+	netlink_ack(skb_in, nlmsg_hdr(skb_in), -EINVAL);
+	return 0;
+
+nla_put_failure:
+	kfree_skb(skb_out);
+	/* Fall through */
+
+fail:
+	return res;
+}
+
+
+static struct genl_ops hsr_ops_get_node_list = {
+	.cmd = HSR_C_GET_NODE_LIST,
+	.flags = 0,
+	.policy = hsr_genl_policy,
+	.doit = hsr_get_node_list,
+	.dumpit = NULL,
+};
+
+int __init hsr_netlink_init(void)
+{
+	int rc;
+
+	rc = rtnl_link_register(&hsr_link_ops);
+	if (rc)
+		goto fail_rtnl_link_register;
+
+	rc = genl_register_family(&hsr_genl_family);
+	if (rc)
+		goto fail_genl_register_family;
+
+	rc = genl_register_ops(&hsr_genl_family, &hsr_ops_get_node_status);
+	if (rc)
+		goto fail_genl_register_ops;
+
+	rc = genl_register_ops(&hsr_genl_family, &hsr_ops_get_node_list);
+	if (rc)
+		goto fail_genl_register_ops_node_list;
+
+	rc = genl_register_mc_group(&hsr_genl_family, &hsr_network_genl_mcgrp);
+	if (rc)
+		goto fail_genl_register_mc_group;
+
+	return 0;
+
+fail_genl_register_mc_group:
+	genl_unregister_ops(&hsr_genl_family, &hsr_ops_get_node_list);
+fail_genl_register_ops_node_list:
+	genl_unregister_ops(&hsr_genl_family, &hsr_ops_get_node_status);
+fail_genl_register_ops:
+	genl_unregister_family(&hsr_genl_family);
+fail_genl_register_family:
+	rtnl_link_unregister(&hsr_link_ops);
+fail_rtnl_link_register:
+
+	return rc;
+}
+
+void __exit hsr_netlink_exit(void)
+{
+	genl_unregister_mc_group(&hsr_genl_family, &hsr_network_genl_mcgrp);
+	genl_unregister_ops(&hsr_genl_family, &hsr_ops_get_node_status);
+	genl_unregister_family(&hsr_genl_family);
+
+	rtnl_link_unregister(&hsr_link_ops);
+}
+
+MODULE_ALIAS_RTNL_LINK("hsr");
diff --git a/net/hsr/hsr_netlink.h b/net/hsr/hsr_netlink.h
new file mode 100644
index 0000000..4f1d6ee
--- /dev/null
+++ b/net/hsr/hsr_netlink.h
@@ -0,0 +1,31 @@
+/*
+ * Copyright 2011-2013 Autronica Fire and Security AS
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * Author(s):
+ *	2011-2013 Arvid Brodin, [email-masked]
+ */
+
+#ifndef __HSR_NETLINK_H
+#define __HSR_NETLINK_H
+
+#include <linux/if_ether.h>
+#include <linux/module.h>
+#include <uapi/linux/hsr_netlink.h>
+
+struct hsr_priv;
+
+int __init hsr_netlink_init(void);
+void __exit hsr_netlink_exit(void);
+
+void hsr_nl_ringerror(struct hsr_priv *hsr_priv, unsigned char addr[ETH_ALEN],
+		      int dev_idx);
+void hsr_nl_nodedown(struct hsr_priv *hsr_priv, unsigned char addr[ETH_ALEN]);
+void hsr_nl_framedrop(int dropcount, int dev_idx);
+void hsr_nl_linkdown(int dev_idx);
+
+#endif /* __HSR_NETLINK_H */
-- 
1.8.1.5

-- 
Arvid Brodin | Consultant (Linux)
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