net: dsa: modularize DSA_TAG_PROTO_NONE

There is no reason that I can see why the no-op tagging protocol should
be registered manually, so make it a module and make all drivers which
have any sort of reference to DSA_TAG_PROTO_NONE select it.

Note that I don't know if ksz_get_tag_protocol() really needs this,
or if it's just the logic which is poorly written. All switches seem to
have their own tagging protocol, and DSA_TAG_PROTO_NONE is just a
fallback that never gets used.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 30 insertions, 0 deletions

diff --git a/net/dsa/tag_none.c b/net/dsa/tag_none.c
new file mode 100644
index 000000000000..34a13c50d245
--- /dev/null
+++ b/net/dsa/tag_none.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * net/dsa/tag_none.c - Traffic handling for switches with no tag
+ * Copyright (c) 2008-2009 Marvell Semiconductor
+ * Copyright (c) 2013 Florian Fainelli <florian@openwrt.org>
+ *
+ * WARNING: do not use this for new switches. In case of no hardware
+ * tagging support, look at tag_8021q.c instead.
+ */
+
+#include "dsa_priv.h"
+
+#define NONE_NAME	"none"
+
+static struct sk_buff *dsa_slave_notag_xmit(struct sk_buff *skb,
+					    struct net_device *dev)
+{
+	/* Just return the original SKB */
+	return skb;
+}
+
+static const struct dsa_device_ops none_ops = {
+	.name	= NONE_NAME,
+	.proto	= DSA_TAG_PROTO_NONE,
+	.xmit	= dsa_slave_notag_xmit,
+};
+
+module_dsa_tag_driver(none_ops);
+MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_NONE, NONE_NAME);
+MODULE_LICENSE("GPL");