[PATCH v1 1/8] net: dsa: Add tag handling for Hirschmann Hellcreek switches

Kurt Kanzenbach
2020-07-10T11:36:38Z

The Hirschmann Hellcreek TSN switches have a special tagging protocol for frames
exchanged between the CPU port and the master interface. The format is a one
byte trailer indicating the destination or origin port.

It's quite similar to the Micrel KSZ tagging. That's why the implementation is
based on that code.

Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
---
include/net/dsa.h | 2 +
net/dsa/Kconfig | 6 +++
net/dsa/Makefile | 1 +
net/dsa/tag_hellcreek.c | 101 ++++++++++++++++++++++++++++++++++++++++
4 files changed, 110 insertions(+)
create mode 100644 net/dsa/tag_hellcreek.c

diff --git a/include/net/dsa.h b/include/net/dsa.h
index b28c95c76762..b4db14ad2713 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -45,6 +45,7 @@ struct phylink_link_state;
#define DSA_TAG_PROTO_OCELOT_VALUE 15
#define DSA_TAG_PROTO_AR9331_VALUE 16
#define DSA_TAG_PROTO_RTL4_A_VALUE 17
+#define DSA_TAG_PROTO_HELLCREEK_VALUE 18

enum dsa_tag_protocol {
DSA_TAG_PROTO_NONE = DSA_TAG_PROTO_NONE_VALUE,
@@ -65,6 +66,7 @@ enum dsa_tag_protocol {
DSA_TAG_PROTO_OCELOT = DSA_TAG_PROTO_OCELOT_VALUE,
DSA_TAG_PROTO_AR9331 = DSA_TAG_PROTO_AR9331_VALUE,
DSA_TAG_PROTO_RTL4_A = DSA_TAG_PROTO_RTL4_A_VALUE,
+ DSA_TAG_PROTO_HELLCREEK = DSA_TAG_PROTO_HELLCREEK_VALUE,
};

struct packet_type;
diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig
index 1f9b9b11008c..d975614f7dd6 100644
--- a/net/dsa/Kconfig
+++ b/net/dsa/Kconfig
@@ -56,6 +56,12 @@ config NET_DSA_TAG_BRCM_PREPEND
Broadcom switches which places the tag before the Ethernet header
(prepended).

+config NET_DSA_TAG_HELLCREEK
+ tristate "Tag driver for Hirschmann Hellcreek TSN switches"
+ help
+ Say Y or M if you want to enable support for tagging frames
+ for the Hirschmann Hellcreek TSN switches.
+
config NET_DSA_TAG_GSWIP
tristate "Tag driver for Lantiq / Intel GSWIP switches"
help
diff --git a/net/dsa/Makefile b/net/dsa/Makefile
index 4f47b2025ff5..e25d5457964a 100644
--- a/net/dsa/Makefile
+++ b/net/dsa/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_NET_DSA_TAG_BRCM_COMMON) += tag_brcm.o
obj-$(CONFIG_NET_DSA_TAG_DSA) += tag_dsa.o
obj-$(CONFIG_NET_DSA_TAG_EDSA) += tag_edsa.o
obj-$(CONFIG_NET_DSA_TAG_GSWIP) += tag_gswip.o
+obj-$(CONFIG_NET_DSA_TAG_HELLCREEK) += tag_hellcreek.o
obj-$(CONFIG_NET_DSA_TAG_KSZ) += tag_ksz.o
obj-$(CONFIG_NET_DSA_TAG_RTL4_A) += tag_rtl4_a.o
obj-$(CONFIG_NET_DSA_TAG_LAN9303) += tag_lan9303.o
diff --git a/net/dsa/tag_hellcreek.c b/net/dsa/tag_hellcreek.c
new file mode 100644
index 000000000000..0895eda94bb5
--- /dev/null
+++ b/net/dsa/tag_hellcreek.c
@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+/*
+ * net/dsa/tag_hellcreek.c - Hirschmann Hellcreek switch tag format handling
+ *
+ * Copyright (C) 2019,2020 Linutronix GmbH
+ * Author Kurt Kanzenbach <kurt@linutronix.de>
+ *
+ * Based on tag_ksz.c.
+ */
+
+#include <linux/etherdevice.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <net/dsa.h>
+
+#include "dsa_priv.h"
+
+#define HELLCREEK_TAG_LEN 1
+
+static struct sk_buff *hellcreek_xmit(struct sk_buff *skb,
+ struct net_device *dev)
+{
+ struct dsa_port *dp = dsa_slave_to_port(dev);
+ struct sk_buff *nskb;
+ int padlen;
+ u8 *tag;
+
+ padlen = (skb->len >= ETH_ZLEN) ? 0 : ETH_ZLEN - skb->len;
+
+ if (skb_tailroom(skb) >= padlen + HELLCREEK_TAG_LEN) {
+ /* Let dsa_slave_xmit() free skb */
+ if (__skb_put_padto(skb, skb->len + padlen, false))
+ return NULL;
+
+ nskb = skb;
+ } else {
+ nskb = alloc_skb(NET_IP_ALIGN + skb->len +
+ padlen + HELLCREEK_TAG_LEN, GFP_ATOMIC);
+ if (!nskb)
+ return NULL;
+ skb_reserve(nskb, NET_IP_ALIGN);
+
+ skb_reset_mac_header(nskb);
+ skb_set_network_header(nskb,
+ skb_network_header(skb) - skb->head);
+ skb_set_transport_header(nskb,
+ skb_transport_header(skb) - skb->head);
+ skb_copy_and_csum_dev(skb, skb_put(nskb, skb->len));
+
+ /* Let skb_put_padto() free nskb, and let dsa_slave_xmit() free
+ * skb
+ */
+ if (skb_put_padto(nskb, nskb->len + padlen))
+ return NULL;
+
+ consume_skb(skb);
+ }
+
+ if (!nskb)
+ return NULL;
+
+ /* Tag encoding */
+ tag = skb_put(nskb, HELLCREEK_TAG_LEN);
+ *tag = BIT(dp->index);
+
+ return nskb;
+}
+
+static struct sk_buff *hellcreek_rcv(struct sk_buff *skb,
+ struct net_device *dev,
+ struct packet_type *pt)
+{
+ /* Tag decoding */
+ u8 *tag = skb_tail_pointer(skb) - HELLCREEK_TAG_LEN;
+ unsigned int port = tag[0] & 0x03;
+
+ skb->dev = dsa_master_find_slave(dev, 0, port);
+ if (!skb->dev) {
+ netdev_warn(dev, "Failed to get source port: %d\n", port);
+ return NULL;
+ }
+
+ pskb_trim_rcsum(skb, skb->len - HELLCREEK_TAG_LEN);
+
+ skb->offload_fwd_mark = true;
+
+ return skb;
+}
+
+static const struct dsa_device_ops hellcreek_netdev_ops = {
+ .name = "hellcreek",
+ .proto = DSA_TAG_PROTO_HELLCREEK,
+ .xmit = hellcreek_xmit,
+ .rcv = hellcreek_rcv,
+ .overhead = HELLCREEK_TAG_LEN,
+};
+
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_HELLCREEK);
+
+module_dsa_tag_driver(hellcreek_netdev_ops);
--
2.20.1