net: hsr: add offloading support

Add support for offloading of HSR/PRP (IEC 62439-3) tag insertion
tag removal, duplicate generation and forwarding.

For HSR, insertion involves the switch adding a 6 byte HSR header after
the 14 byte Ethernet header. For PRP it adds a 6 byte trailer.

Tag removal involves automatically stripping the HSR/PRP header/trailer
in the switch. This is possible when the switch also performs auto
deduplication using the HSR/PRP header/trailer (making it no longer
required).

Forwarding involves automatically forwarding between redundant ports in
an HSR. This is crucial because delay is accumulated as a frame passes
through each node in the ring.

Duplication involves the switch automatically sending a single frame
from the CPU port to both redundant ports. This is required because the
inserted HSR/PRP header/trailer must contain the same sequence number
on the frames sent out both redundant ports.

Export is_hsr_master so DSA can tell them apart from other devices in
dsa_slave_changeupper.

Signed-off-by: George McCollister <[e-mail]>
Reviewed-by: Vladimir Oltean <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

Documentation/networking/netdev-features.rst

···
 be re-segmentable by GSO or TSO back to the exact original packet stream.
 Hardware GRO is dependent on RXCSUM since every packet successfully merged
 by hardware must also have the checksum verified by hardware.
+
+* hsr-tag-ins-offload
+
+This should be set for devices which insert an HSR (High-availability Seamless
+Redundancy) or PRP (Parallel Redundancy Protocol) tag automatically.
+
+* hsr-tag-rm-offload
+
+This should be set for devices which remove HSR (High-availability Seamless
+Redundancy) or PRP (Parallel Redundancy Protocol) tags automatically.
+
+* hsr-fwd-offload
+
+This should be set for devices which forward HSR (High-availability Seamless
+Redundancy) frames from one port to another in hardware.
+
+* hsr-dup-offload
+
+This should be set for devices which duplicate outgoing HSR (High-availability
+Seamless Redundancy) or PRP (Parallel Redundancy Protocol) tags automatically
+frames in hardware.

include/linux/if_hsr.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_IF_HSR_H_
+#define _LINUX_IF_HSR_H_
+
+/* used to differentiate various protocols */
+enum hsr_version {
+	HSR_V0 = 0,
+	HSR_V1,
+	PRP_V1,
+};
+
+#if IS_ENABLED(CONFIG_HSR)
+extern bool is_hsr_master(struct net_device *dev);
+extern int hsr_get_version(struct net_device *dev, enum hsr_version *ver);
+#else
+static inline bool is_hsr_master(struct net_device *dev)
+{
+	return false;
+}
+static inline int hsr_get_version(struct net_device *dev,
+				  enum hsr_version *ver)
+{
+	return -EINVAL;
+}
+#endif /* CONFIG_HSR */
+
+#endif /*_LINUX_IF_HSR_H_*/

include/linux/netdev_features.h

···
 	NETIF_F_HW_MACSEC_BIT,		/* Offload MACsec operations */
 	NETIF_F_GRO_UDP_FWD_BIT,	/* Allow UDP GRO for forwarding */
 
+	NETIF_F_HW_HSR_TAG_INS_BIT,	/* Offload HSR tag insertion */
+	NETIF_F_HW_HSR_TAG_RM_BIT,	/* Offload HSR tag removal */
+	NETIF_F_HW_HSR_FWD_BIT,		/* Offload HSR forwarding */
+	NETIF_F_HW_HSR_DUP_BIT,		/* Offload HSR duplication */
+
 	/*
 	 * Add your fresh new feature above and remember to update
 	 * netdev_features_strings[] in net/core/ethtool.c and maybe
···
 #define NETIF_F_GSO_FRAGLIST	__NETIF_F(GSO_FRAGLIST)
 #define NETIF_F_HW_MACSEC	__NETIF_F(HW_MACSEC)
 #define NETIF_F_GRO_UDP_FWD	__NETIF_F(GRO_UDP_FWD)
+#define NETIF_F_HW_HSR_TAG_INS	__NETIF_F(HW_HSR_TAG_INS)
+#define NETIF_F_HW_HSR_TAG_RM	__NETIF_F(HW_HSR_TAG_RM)
+#define NETIF_F_HW_HSR_FWD	__NETIF_F(HW_HSR_FWD)
+#define NETIF_F_HW_HSR_DUP	__NETIF_F(HW_HSR_DUP)
 
 /* Finds the next feature with the highest number of the range of start till 0.
  */

net/ethtool/common.c

···
 	[NETIF_F_GRO_FRAGLIST_BIT] =	 "rx-gro-list",
 	[NETIF_F_HW_MACSEC_BIT] =	 "macsec-hw-offload",
 	[NETIF_F_GRO_UDP_FWD_BIT] =	 "rx-udp-gro-forwarding",
+	[NETIF_F_HW_HSR_TAG_INS_BIT] =	 "hsr-tag-ins-offload",
+	[NETIF_F_HW_HSR_TAG_RM_BIT] =	 "hsr-tag-rm-offload",
+	[NETIF_F_HW_HSR_FWD_BIT] =	 "hsr-fwd-offload",
+	[NETIF_F_HW_HSR_DUP_BIT] =	 "hsr-dup-offload",
 };
 
 const char

net/hsr/hsr_device.c

···
 	.send_sv_frame = send_hsr_supervision_frame,
 	.create_tagged_frame = hsr_create_tagged_frame,
 	.get_untagged_frame = hsr_get_untagged_frame,
+	.drop_frame = hsr_drop_frame,
 	.fill_frame_info = hsr_fill_frame_info,
 	.invalid_dan_ingress_frame = hsr_invalid_dan_ingress_frame,
 };
···
 
 /* Return true if dev is a HSR master; return false otherwise.
  */
-inline bool is_hsr_master(struct net_device *dev)
+bool is_hsr_master(struct net_device *dev)
 {
 	return (dev->netdev_ops->ndo_start_xmit == hsr_dev_xmit);
 }
+EXPORT_SYMBOL(is_hsr_master);
 
 /* Default multicast address for HSR Supervision frames */
 static const unsigned char def_multicast_addr[ETH_ALEN] __aligned(2) = {
···
 	hsr->sup_multicast_addr[ETH_ALEN - 1] = multicast_spec;
 
 	hsr->prot_version = protocol_version;
-
-	/* 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?
-	 */
 
 	/* Make sure the 1st call to netif_carrier_on() gets through */
 	netif_carrier_off(hsr_dev);

net/hsr/hsr_device.h

···
 		     unsigned char multicast_spec, u8 protocol_version,
 		     struct netlink_ext_ack *extack);
 void hsr_check_carrier_and_operstate(struct hsr_priv *hsr);
-bool is_hsr_master(struct net_device *dev);
 int hsr_get_max_mtu(struct hsr_priv *hsr);
 #endif /* __HSR_DEVICE_H */

net/hsr/hsr_forward.c

···
 		/* set the lane id properly */
 		hsr_set_path_id(hsr_ethhdr, port);
 		return skb_clone(frame->skb_hsr, GFP_ATOMIC);
+	} else if (port->dev->features & NETIF_F_HW_HSR_TAG_INS) {
+		return skb_clone(frame->skb_std, GFP_ATOMIC);
 	}
 
 	/* Create the new skb with enough headroom to fit the HSR tag */
···
 			return NULL;
 		}
 		return skb_clone(frame->skb_prp, GFP_ATOMIC);
+	} else if (port->dev->features & NETIF_F_HW_HSR_TAG_INS) {
+		return skb_clone(frame->skb_std, GFP_ATOMIC);
 	}
 
 	skb = skb_copy_expand(frame->skb_std, 0,
···
 		 port->type ==  HSR_PT_SLAVE_A));
 }
 
+bool hsr_drop_frame(struct hsr_frame_info *frame, struct hsr_port *port)
+{
+	if (port->dev->features & NETIF_F_HW_HSR_FWD)
+		return prp_drop_frame(frame, port);
+
+	return false;
+}
+
 /* Forward the frame through all devices except:
  * - Back through the receiving device
  * - If it's a HSR frame: through a device where it has passed before
···
 {
 	struct hsr_port *port;
 	struct sk_buff *skb;
+	bool sent = false;
 
 	hsr_for_each_port(frame->port_rcv->hsr, port) {
 		struct hsr_priv *hsr = port->hsr;
···
 
 		/* Deliver frames directly addressed to us to master only */
 		if (port->type != HSR_PT_MASTER && frame->is_local_exclusive)
+			continue;
+
+		/* If hardware duplicate generation is enabled, only send out
+		 * one port.
+		 */
+		if ((port->dev->features & NETIF_F_HW_HSR_DUP) && sent)
 			continue;
 
 		/* Don't send frame over port where it has been sent before.
···
 		}
 
 		skb->dev = port->dev;
-		if (port->type == HSR_PT_MASTER)
+		if (port->type == HSR_PT_MASTER) {
 			hsr_deliver_master(skb, port->dev, frame->node_src);
-		else
-			hsr_xmit(skb, port, frame);
+		} else {
+			if (!hsr_xmit(skb, port, frame))
+				sent = true;
+		}
 	}
 }
 

net/hsr/hsr_forward.h

···
 struct sk_buff *prp_get_untagged_frame(struct hsr_frame_info *frame,
 				       struct hsr_port *port);
 bool prp_drop_frame(struct hsr_frame_info *frame, struct hsr_port *port);
+bool hsr_drop_frame(struct hsr_frame_info *frame, struct hsr_port *port);
 void prp_fill_frame_info(__be16 proto, struct sk_buff *skb,
 			 struct hsr_frame_info *frame);
 void hsr_fill_frame_info(__be16 proto, struct sk_buff *skb,

net/hsr/hsr_framereg.c

···
 		skb = frame->skb_hsr;
 	else if (frame->skb_prp)
 		skb = frame->skb_prp;
+	else if (frame->skb_std)
+		skb = frame->skb_std;
 	if (!skb)
 		return;
 

net/hsr/hsr_main.c

···
 	return NULL;
 }
 
+int hsr_get_version(struct net_device *dev, enum hsr_version *ver)
+{
+	struct hsr_priv *hsr;
+
+	hsr = netdev_priv(dev);
+	*ver = hsr->prot_version;
+
+	return 0;
+}
+EXPORT_SYMBOL(hsr_get_version);
+
 static struct notifier_block hsr_nb = {
 	.notifier_call = hsr_netdev_notify,	/* Slave event notifications */
 };

net/hsr/hsr_main.h

···
 #include <linux/netdevice.h>
 #include <linux/list.h>
 #include <linux/if_vlan.h>
+#include <linux/if_hsr.h>
 
 /* Time constants as specified in the HSR specification (IEC-62439-3 2010)
  * Table 8.
···
 	struct net_device	*dev;
 	struct hsr_priv		*hsr;
 	enum hsr_port_type	type;
-};
-
-/* used by driver internally to differentiate various protocols */
-enum hsr_version {
-	HSR_V0 = 0,
-	HSR_V1,
-	PRP_V1,
 };
 
 struct hsr_frame_info;

net/hsr/hsr_slave.c

···
 		goto finish_consume;
 	}
 
-	/* For HSR, only tagged frames are expected, but for PRP
-	 * there could be non tagged frames as well from Single
-	 * attached nodes (SANs).
+	/* For HSR, only tagged frames are expected (unless the device offloads
+	 * HSR tag removal), but for PRP there could be non tagged frames as
+	 * well from Single attached nodes (SANs).
 	 */
 	protocol = eth_hdr(skb)->h_proto;
-	if (hsr->proto_ops->invalid_dan_ingress_frame &&
+
+	if (!(port->dev->features & NETIF_F_HW_HSR_TAG_RM) &&
+	    hsr->proto_ops->invalid_dan_ingress_frame &&
 	    hsr->proto_ops->invalid_dan_ingress_frame(protocol))
 		goto finish_pass;