dsa: Add boilerplate helper to register DSA tag driver modules

A DSA tag driver module will need to register the tag protocols it
implements with the DSA core. Add macros containing this boiler plate.

The registration/unregistration code is currently just a stub. A Later
patch will add the real implementation.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>

v2
Fix indent of #endif
Rewrite to move list pointer into a new structure
v3
Move kdoc next to macro
Fix THIS_MODULE indentation
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dsa.h

@@ -594,4 +594,70 @@ int dsa_port_get_ethtool_phy_stats(struct dsa_port *dp, uint64_t *data);
 int dsa_port_get_phy_sset_count(struct dsa_port *dp);
 void dsa_port_phylink_mac_change(struct dsa_switch *ds, int port, bool up);
 
+struct dsa_tag_driver {
+	const struct dsa_device_ops *ops;
+	struct list_head list;
+	struct module *owner;
+};
+
+void dsa_tag_drivers_register(struct dsa_tag_driver *dsa_tag_driver_array[],
+			      unsigned int count,
+			      struct module *owner);
+void dsa_tag_drivers_unregister(struct dsa_tag_driver *dsa_tag_driver_array[],
+				unsigned int count);
+
+#define dsa_tag_driver_module_drivers(__dsa_tag_drivers_array, __count)	\
+static int __init dsa_tag_driver_module_init(void)			\
+{									\
+	dsa_tag_drivers_register(__dsa_tag_drivers_array, __count,	\
+				 THIS_MODULE);				\
+	return 0;							\
+}									\
+module_init(dsa_tag_driver_module_init);				\
+									\
+static void __exit dsa_tag_driver_module_exit(void)			\
+{									\
+	dsa_tag_drivers_unregister(__dsa_tag_drivers_array, __count);	\
+}									\
+module_exit(dsa_tag_driver_module_exit)
+
+/**
+ * module_dsa_tag_drivers() - Helper macro for registering DSA tag
+ * drivers
+ * @__ops_array: Array of tag driver strucutres
+ *
+ * Helper macro for DSA tag drivers which do not do anything special
+ * in module init/exit. Each module may only use this macro once, and
+ * calling it replaces module_init() and module_exit().
+ */
+#define module_dsa_tag_drivers(__ops_array)				\
+dsa_tag_driver_module_drivers(__ops_array, ARRAY_SIZE(__ops_array))
+
+#define DSA_TAG_DRIVER_NAME(__ops) dsa_tag_driver ## _ ## __ops
+
+/* Create a static structure we can build a linked list of dsa_tag
+ * drivers
+ */
+#define DSA_TAG_DRIVER(__ops)						\
+static struct dsa_tag_driver DSA_TAG_DRIVER_NAME(__ops) = {		\
+	.ops = &__ops,							\
+}
+
+/**
+ * module_dsa_tag_driver() - Helper macro for registering a single DSA tag
+ * driver
+ * @__ops: Single tag driver structures
+ *
+ * Helper macro for DSA tag drivers which do not do anything special
+ * in module init/exit. Each module may only use this macro once, and
+ * calling it replaces module_init() and module_exit().
+ */
+#define module_dsa_tag_driver(__ops)					\
+DSA_TAG_DRIVER(__ops);							\
+									\
+static struct dsa_tag_driver *dsa_tag_driver_array[] =	{		\
+	&DSA_TAG_DRIVER_NAME(__ops)					\
+};									\
+module_dsa_tag_drivers(dsa_tag_driver_array)
 #endif
+

net/dsa/dsa.c

@@ -76,6 +76,18 @@ const struct dsa_device_ops *dsa_device_ops[DSA_TAG_LAST] = {
 	[DSA_TAG_PROTO_NONE] = &none_ops,
 };
 
+void dsa_tag_drivers_register(struct dsa_tag_driver *dsa_tag_driver_array[],
+			      unsigned int count, struct module *owner)
+{
+}
+EXPORT_SYMBOL_GPL(dsa_tag_drivers_register);
+
+void dsa_tag_drivers_unregister(struct dsa_tag_driver *dsa_tag_driver_array[],
+				unsigned int count)
+{
+}
+EXPORT_SYMBOL_GPL(dsa_tag_drivers_unregister);
+
 const char *dsa_tag_protocol_to_str(const struct dsa_device_ops *ops)
 {
 	return ops->name;

net/dsa/tag_brcm.c

@@ -175,6 +175,7 @@ const struct dsa_device_ops brcm_netdev_ops = {
 	.overhead = BRCM_TAG_LEN,
 };
 
+DSA_TAG_DRIVER(brcm_netdev_ops);
 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM);
 #endif
 
@@ -203,5 +204,18 @@ const struct dsa_device_ops brcm_prepend_netdev_ops = {
 };
 #endif
 
-MODULE_LICENSE("GPL");
+DSA_TAG_DRIVER(brcm_prepend_netdev_ops);
 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_PREPEND);
+
+static struct dsa_tag_driver *dsa_tag_driver_array[] =	{
+#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
+	&DSA_TAG_DRIVER_NAME(brcm_netdev_ops),
+#endif
+#if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
+	&DSA_TAG_DRIVER_NAME(brcm_prepend_netdev_ops),
+#endif
+};
+
+module_dsa_tag_drivers(dsa_tag_driver_array);
+
+MODULE_LICENSE("GPL");

net/dsa/tag_dsa.c

@@ -161,3 +161,5 @@ const struct dsa_device_ops dsa_netdev_ops = {
 
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_DSA);
+
+module_dsa_tag_driver(dsa_netdev_ops);

net/dsa/tag_edsa.c

@@ -180,3 +180,5 @@ const struct dsa_device_ops edsa_netdev_ops = {
 
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_EDSA);
+
+module_dsa_tag_driver(edsa_netdev_ops);

net/dsa/tag_gswip.c

@@ -113,3 +113,5 @@ const struct dsa_device_ops gswip_netdev_ops = {
 
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_GSWIP);
+
+module_dsa_tag_driver(gswip_netdev_ops);

net/dsa/tag_ksz.c

@@ -141,6 +141,7 @@ const struct dsa_device_ops ksz9477_netdev_ops = {
 	.overhead = KSZ9477_INGRESS_TAG_LEN,
 };
 
+DSA_TAG_DRIVER(ksz9477_netdev_ops);
 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_KSZ9477);
 
 #define KSZ9893_TAIL_TAG_OVERRIDE	BIT(5)
@@ -178,5 +179,14 @@ const struct dsa_device_ops ksz9893_netdev_ops = {
 	.overhead = KSZ_INGRESS_TAG_LEN,
 };
 
-MODULE_LICENSE("GPL");
+DSA_TAG_DRIVER(ksz9893_netdev_ops);
 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_KSZ9893);
+
+static struct dsa_tag_driver *dsa_tag_driver_array[] = {
+	&DSA_TAG_DRIVER_NAME(ksz9477_netdev_ops),
+	&DSA_TAG_DRIVER_NAME(ksz9893_netdev_ops),
+};
+
+module_dsa_tag_drivers(dsa_tag_driver_array);
+
+MODULE_LICENSE("GPL");

net/dsa/tag_lan9303.c

@@ -138,3 +138,5 @@ const struct dsa_device_ops lan9303_netdev_ops = {
 
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_LAN9303);
+
+module_dsa_tag_driver(lan9303_netdev_ops);

net/dsa/tag_mtk.c

@@ -109,3 +109,5 @@ const struct dsa_device_ops mtk_netdev_ops = {
 
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MTK);
+
+module_dsa_tag_driver(mtk_netdev_ops);

net/dsa/tag_qca.c

@@ -110,3 +110,5 @@ const struct dsa_device_ops qca_netdev_ops = {
 
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_QCA);
+
+module_dsa_tag_driver(qca_netdev_ops);

net/dsa/tag_trailer.c

@@ -87,3 +87,5 @@ const struct dsa_device_ops trailer_netdev_ops = {
 
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_TRAILER);
+
+module_dsa_tag_driver(trailer_netdev_ops);