marvell/linux/include/net/dsa.h

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * include/net/dsa.h - Driver for Distributed Switch Architecture switch chips
 * Copyright (c) 2008-2009 Marvell Semiconductor
 */

#ifndef __LINUX_NET_DSA_H
#define __LINUX_NET_DSA_H

#include <linux/if.h>
#include <linux/if_ether.h>
#include <linux/list.h>
#include <linux/notifier.h>
#include <linux/timer.h>
#include <linux/workqueue.h>
#include <linux/of.h>
#include <linux/ethtool.h>
#include <linux/net_tstamp.h>
#include <linux/phy.h>
#include <linux/platform_data/dsa.h>
#include <linux/phylink.h>
#include <net/devlink.h>
#include <net/switchdev.h>

struct tc_action;
struct phy_device;
struct fixed_phy_status;
struct phylink_link_state;

#define DSA_TAG_PROTO_NONE_VALUE		0
#define DSA_TAG_PROTO_BRCM_VALUE		1
#define DSA_TAG_PROTO_BRCM_PREPEND_VALUE	2
#define DSA_TAG_PROTO_DSA_VALUE			3
#define DSA_TAG_PROTO_EDSA_VALUE		4
#define DSA_TAG_PROTO_GSWIP_VALUE		5
#define DSA_TAG_PROTO_KSZ9477_VALUE		6
#define DSA_TAG_PROTO_KSZ9893_VALUE		7
#define DSA_TAG_PROTO_LAN9303_VALUE		8
#define DSA_TAG_PROTO_MTK_VALUE			9
#define DSA_TAG_PROTO_QCA_VALUE			10
#define DSA_TAG_PROTO_TRAILER_VALUE		11
#define DSA_TAG_PROTO_8021Q_VALUE		12
#define DSA_TAG_PROTO_SJA1105_VALUE		13
#define DSA_TAG_PROTO_KSZ8795_VALUE		14
#define DSA_TAG_PROTO_RTL4_A_VALUE		17

enum dsa_tag_protocol {
	DSA_TAG_PROTO_NONE		= DSA_TAG_PROTO_NONE_VALUE,
	DSA_TAG_PROTO_BRCM		= DSA_TAG_PROTO_BRCM_VALUE,
	DSA_TAG_PROTO_BRCM_PREPEND	= DSA_TAG_PROTO_BRCM_PREPEND_VALUE,
	DSA_TAG_PROTO_DSA		= DSA_TAG_PROTO_DSA_VALUE,
	DSA_TAG_PROTO_EDSA		= DSA_TAG_PROTO_EDSA_VALUE,
	DSA_TAG_PROTO_GSWIP		= DSA_TAG_PROTO_GSWIP_VALUE,
	DSA_TAG_PROTO_KSZ9477		= DSA_TAG_PROTO_KSZ9477_VALUE,
	DSA_TAG_PROTO_KSZ9893		= DSA_TAG_PROTO_KSZ9893_VALUE,
	DSA_TAG_PROTO_LAN9303		= DSA_TAG_PROTO_LAN9303_VALUE,
	DSA_TAG_PROTO_MTK		= DSA_TAG_PROTO_MTK_VALUE,
	DSA_TAG_PROTO_QCA		= DSA_TAG_PROTO_QCA_VALUE,
	DSA_TAG_PROTO_TRAILER		= DSA_TAG_PROTO_TRAILER_VALUE,
	DSA_TAG_PROTO_8021Q		= DSA_TAG_PROTO_8021Q_VALUE,
	DSA_TAG_PROTO_SJA1105		= DSA_TAG_PROTO_SJA1105_VALUE,
	DSA_TAG_PROTO_KSZ8795		= DSA_TAG_PROTO_KSZ8795_VALUE,
	DSA_TAG_PROTO_RTL4_A		= DSA_TAG_PROTO_RTL4_A_VALUE,
};

struct packet_type;
struct dsa_switch;

struct dsa_device_ops {
	struct sk_buff *(*xmit)(struct sk_buff *skb, struct net_device *dev);
	struct sk_buff *(*rcv)(struct sk_buff *skb, struct net_device *dev,
			       struct packet_type *pt);
	int (*flow_dissect)(const struct sk_buff *skb, __be16 *proto,
			    int *offset);
	/* Used to determine which traffic should match the DSA filter in
	 * eth_type_trans, and which, if any, should bypass it and be processed
	 * as regular on the master net device.
	 */
	bool (*filter)(const struct sk_buff *skb, struct net_device *dev);
	unsigned int overhead;
	const char *name;
	enum dsa_tag_protocol proto;
};

#define DSA_TAG_DRIVER_ALIAS "dsa_tag-"
#define MODULE_ALIAS_DSA_TAG_DRIVER(__proto)				\
	MODULE_ALIAS(DSA_TAG_DRIVER_ALIAS __stringify(__proto##_VALUE))

struct dsa_skb_cb {
	struct sk_buff *clone;
	bool deferred_xmit;
};

struct __dsa_skb_cb {
	struct dsa_skb_cb cb;
	u8 priv[48 - sizeof(struct dsa_skb_cb)];
};

#define __DSA_SKB_CB(skb) ((struct __dsa_skb_cb *)((skb)->cb))

#define DSA_SKB_CB(skb) ((struct dsa_skb_cb *)((skb)->cb))

#define DSA_SKB_CB_PRIV(skb)			\
	((void *)(skb)->cb + offsetof(struct __dsa_skb_cb, priv))

struct dsa_switch_tree {
	struct list_head	list;

	/* Notifier chain for switch-wide events */
	struct raw_notifier_head	nh;

	/* Tree identifier */
	unsigned int index;

	/* Number of switches attached to this tree */
	struct kref refcount;

	/* Has this tree been applied to the hardware? */
	bool setup;

	/*
	 * Configuration data for the platform device that owns
	 * this dsa switch tree instance.
	 */
	struct dsa_platform_data	*pd;

	/*
	 * The switch port to which the CPU is attached.
	 */
	struct dsa_port		*cpu_dp;

	/*
	 * Data for the individual switch chips.
	 */
	struct dsa_switch	*ds[DSA_MAX_SWITCHES];
};

/* TC matchall action types, only mirroring for now */
enum dsa_port_mall_action_type {
	DSA_PORT_MALL_MIRROR,
};

/* TC mirroring entry */
struct dsa_mall_mirror_tc_entry {
	u8 to_local_port;
	bool ingress;
};

/* TC matchall entry */
struct dsa_mall_tc_entry {
	struct list_head list;
	unsigned long cookie;
	enum dsa_port_mall_action_type type;
	union {
		struct dsa_mall_mirror_tc_entry mirror;
	};
};


struct dsa_port {
	/* A CPU port is physically connected to a master device.
	 * A user port exposed to userspace has a slave device.
	 */
	union {
		struct net_device *master;
		struct net_device *slave;
	};

	/* CPU port tagging operations used by master or slave devices */
	const struct dsa_device_ops *tag_ops;

	/* Copies for faster access in master receive hot path */
	struct dsa_switch_tree *dst;
	struct sk_buff *(*rcv)(struct sk_buff *skb, struct net_device *dev,
			       struct packet_type *pt);
	bool (*filter)(const struct sk_buff *skb, struct net_device *dev);

	enum {
		DSA_PORT_TYPE_UNUSED = 0,
		DSA_PORT_TYPE_CPU,
		DSA_PORT_TYPE_DSA,
		DSA_PORT_TYPE_USER,
	} type;

	struct dsa_switch	*ds;
	unsigned int		index;
	const char		*name;
	struct dsa_port		*cpu_dp;
	const char		*mac;
	struct device_node	*dn;
	unsigned int		ageing_time;
	bool			vlan_filtering;
	u8			stp_state;
	struct net_device	*bridge_dev;
	struct devlink_port	devlink_port;
	struct phylink		*pl;
	struct phylink_config	pl_config;

	struct work_struct	xmit_work;
	struct sk_buff_head	xmit_queue;

	/*
	 * Give the switch driver somewhere to hang its per-port private data
	 * structures (accessible from the tagger).
	 */
	void *priv;

	/*
	 * Original copy of the master netdev ethtool_ops
	 */
	const struct ethtool_ops *orig_ethtool_ops;

	/*
	 * Original copy of the master netdev net_device_ops
	 */
	const struct net_device_ops *orig_ndo_ops;
};

struct dsa_switch {
	struct device *dev;

	/*
	 * Parent switch tree, and switch index.
	 */
	struct dsa_switch_tree	*dst;
	unsigned int		index;

	/* Listener for switch fabric events */
	struct notifier_block	nb;

	/*
	 * Give the switch driver somewhere to hang its private data
	 * structure.
	 */
	void *priv;

	/*
	 * Configuration data for this switch.
	 */
	struct dsa_chip_data	*cd;

	/*
	 * The switch operations.
	 */
	const struct dsa_switch_ops	*ops;

	/*
	 * An array of which element [a] indicates which port on this
	 * switch should be used to send packets to that are destined
	 * for switch a. Can be NULL if there is only one switch chip.
	 */
	s8		rtable[DSA_MAX_SWITCHES];

	/*
	 * Slave mii_bus and devices for the individual ports.
	 */
	u32			phys_mii_mask;
	struct mii_bus		*slave_mii_bus;

	/* Ageing Time limits in msecs */
	unsigned int ageing_time_min;
	unsigned int ageing_time_max;

	/* devlink used to represent this switch device */
	struct devlink		*devlink;

	/* Number of switch port queues */
	unsigned int		num_tx_queues;

	/* Disallow bridge core from requesting different VLAN awareness
	 * settings on ports if not hardware-supported
	 */
	bool			vlan_filtering_is_global;

	/* Pass .port_vlan_add and .port_vlan_del to drivers even for bridges
	 * that have vlan_filtering=0. All drivers should ideally set this (and
	 * then the option would get removed), but it is unknown whether this
	 * would break things or not.
	 */
	bool			configure_vlan_while_not_filtering;

	/* Let DSA manage the FDB entries towards the CPU, based on the
	 * software bridge database.
	 */
	bool			assisted_learning_on_cpu_port;

	/* In case vlan_filtering_is_global is set, the VLAN awareness state
	 * should be retrieved from here and not from the per-port settings.
	 */
	bool			vlan_filtering;

	/* Dynamically allocated ports, keep last */
	size_t num_ports;
	struct dsa_port ports[];
};

static inline const struct dsa_port *dsa_to_port(struct dsa_switch *ds, int p)
{
	return &ds->ports[p];
}

static inline bool dsa_is_unused_port(struct dsa_switch *ds, int p)
{
	return dsa_to_port(ds, p)->type == DSA_PORT_TYPE_UNUSED;
}

static inline bool dsa_is_cpu_port(struct dsa_switch *ds, int p)
{
	return dsa_to_port(ds, p)->type == DSA_PORT_TYPE_CPU;
}

static inline bool dsa_is_dsa_port(struct dsa_switch *ds, int p)
{
	return dsa_to_port(ds, p)->type == DSA_PORT_TYPE_DSA;
}

static inline bool dsa_is_user_port(struct dsa_switch *ds, int p)
{
	return dsa_to_port(ds, p)->type == DSA_PORT_TYPE_USER;
}

static inline u32 dsa_user_ports(struct dsa_switch *ds)
{
	u32 mask = 0;
	int p;

	for (p = 0; p < ds->num_ports; p++)
		if (dsa_is_user_port(ds, p))
			mask |= BIT(p);

	return mask;
}

/* Return the local port used to reach an arbitrary switch port */
static inline unsigned int dsa_towards_port(struct dsa_switch *ds, int device,
					    int port)
{
	if (device == ds->index)
		return port;
	else
		return ds->rtable[device];
}

/* Return the local port used to reach the dedicated CPU port */
static inline unsigned int dsa_upstream_port(struct dsa_switch *ds, int port)
{
	const struct dsa_port *dp = dsa_to_port(ds, port);
	const struct dsa_port *cpu_dp = dp->cpu_dp;

	if (!cpu_dp)
		return port;

	return dsa_towards_port(ds, cpu_dp->ds->index, cpu_dp->index);
}

static inline bool dsa_port_is_vlan_filtering(const struct dsa_port *dp)
{
	const struct dsa_switch *ds = dp->ds;

	if (ds->vlan_filtering_is_global)
		return ds->vlan_filtering;
	else
		return dp->vlan_filtering;
}

typedef int dsa_fdb_dump_cb_t(const unsigned char *addr, u16 vid,
			      bool is_static, void *data);
struct dsa_switch_ops {
	enum dsa_tag_protocol (*get_tag_protocol)(struct dsa_switch *ds,
						  int port,
						  enum dsa_tag_protocol mprot);

	int	(*setup)(struct dsa_switch *ds);
	void	(*teardown)(struct dsa_switch *ds);
	u32	(*get_phy_flags)(struct dsa_switch *ds, int port);

	/*
	 * Access to the switch's PHY registers.
	 */
	int	(*phy_read)(struct dsa_switch *ds, int port, int regnum);
	int	(*phy_write)(struct dsa_switch *ds, int port,
			     int regnum, u16 val);

	/*
	 * Link state adjustment (called from libphy)
	 */
	void	(*adjust_link)(struct dsa_switch *ds, int port,
				struct phy_device *phydev);
	void	(*fixed_link_update)(struct dsa_switch *ds, int port,
				struct fixed_phy_status *st);

	/*
	 * PHYLINK integration
	 */
	void	(*phylink_validate)(struct dsa_switch *ds, int port,
				    unsigned long *supported,
				    struct phylink_link_state *state);
	int	(*phylink_mac_link_state)(struct dsa_switch *ds, int port,
					  struct phylink_link_state *state);
	void	(*phylink_mac_config)(struct dsa_switch *ds, int port,
				      unsigned int mode,
				      const struct phylink_link_state *state);
	void	(*phylink_mac_an_restart)(struct dsa_switch *ds, int port);
	void	(*phylink_mac_link_down)(struct dsa_switch *ds, int port,
					 unsigned int mode,
					 phy_interface_t interface);
	void	(*phylink_mac_link_up)(struct dsa_switch *ds, int port,
				       unsigned int mode,
				       phy_interface_t interface,
				       struct phy_device *phydev);
	void	(*phylink_fixed_state)(struct dsa_switch *ds, int port,
				       struct phylink_link_state *state);
	/*
	 * ethtool hardware statistics.
	 */
	void	(*get_strings)(struct dsa_switch *ds, int port,
			       u32 stringset, uint8_t *data);
	void	(*get_ethtool_stats)(struct dsa_switch *ds,
				     int port, uint64_t *data);
	int	(*get_sset_count)(struct dsa_switch *ds, int port, int sset);
	void	(*get_ethtool_phy_stats)(struct dsa_switch *ds,
					 int port, uint64_t *data);

	/*
	 * ethtool Wake-on-LAN
	 */
	void	(*get_wol)(struct dsa_switch *ds, int port,
			   struct ethtool_wolinfo *w);
	int	(*set_wol)(struct dsa_switch *ds, int port,
			   struct ethtool_wolinfo *w);

	/*
	 * ethtool timestamp info
	 */
	int	(*get_ts_info)(struct dsa_switch *ds, int port,
			       struct ethtool_ts_info *ts);

	/*
	 * Suspend and resume
	 */
	int	(*suspend)(struct dsa_switch *ds);
	int	(*resume)(struct dsa_switch *ds);

	/*
	 * Port enable/disable
	 */
	int	(*port_enable)(struct dsa_switch *ds, int port,
			       struct phy_device *phy);
	void	(*port_disable)(struct dsa_switch *ds, int port);

	/*
	 * Port's MAC EEE settings
	 */
	int	(*set_mac_eee)(struct dsa_switch *ds, int port,
			       struct ethtool_eee *e);
	int	(*get_mac_eee)(struct dsa_switch *ds, int port,
			       struct ethtool_eee *e);

	/* EEPROM access */
	int	(*get_eeprom_len)(struct dsa_switch *ds);
	int	(*get_eeprom)(struct dsa_switch *ds,
			      struct ethtool_eeprom *eeprom, u8 *data);
	int	(*set_eeprom)(struct dsa_switch *ds,
			      struct ethtool_eeprom *eeprom, u8 *data);

	/*
	 * Register access.
	 */
	int	(*get_regs_len)(struct dsa_switch *ds, int port);
	void	(*get_regs)(struct dsa_switch *ds, int port,
			    struct ethtool_regs *regs, void *p);

	/*
	 * Bridge integration
	 */
	int	(*set_ageing_time)(struct dsa_switch *ds, unsigned int msecs);
	int	(*port_bridge_join)(struct dsa_switch *ds, int port,
				    struct net_device *bridge);
	void	(*port_bridge_leave)(struct dsa_switch *ds, int port,
				     struct net_device *bridge);
	void	(*port_stp_state_set)(struct dsa_switch *ds, int port,
				      u8 state);
	void	(*port_fast_age)(struct dsa_switch *ds, int port);
	int	(*port_egress_floods)(struct dsa_switch *ds, int port,
				      bool unicast, bool multicast);

	/*
	 * VLAN support
	 */
	int	(*port_vlan_filtering)(struct dsa_switch *ds, int port,
				       bool vlan_filtering);
	int (*port_vlan_prepare)(struct dsa_switch *ds, int port,
				 const struct switchdev_obj_port_vlan *vlan);
	void (*port_vlan_add)(struct dsa_switch *ds, int port,
			      const struct switchdev_obj_port_vlan *vlan);
	int	(*port_vlan_del)(struct dsa_switch *ds, int port,
				 const struct switchdev_obj_port_vlan *vlan);
	/*
	 * Forwarding database
	 */
	int	(*port_fdb_add)(struct dsa_switch *ds, int port,
				const unsigned char *addr, u16 vid);
	int	(*port_fdb_del)(struct dsa_switch *ds, int port,
				const unsigned char *addr, u16 vid);
	int	(*port_fdb_dump)(struct dsa_switch *ds, int port,
				 dsa_fdb_dump_cb_t *cb, void *data);

	/*
	 * Multicast database
	 */
	int (*port_mdb_prepare)(struct dsa_switch *ds, int port,
				const struct switchdev_obj_port_mdb *mdb);
	void (*port_mdb_add)(struct dsa_switch *ds, int port,
			     const struct switchdev_obj_port_mdb *mdb);
	int	(*port_mdb_del)(struct dsa_switch *ds, int port,
				const struct switchdev_obj_port_mdb *mdb);
	/*
	 * RXNFC
	 */
	int	(*get_rxnfc)(struct dsa_switch *ds, int port,
			     struct ethtool_rxnfc *nfc, u32 *rule_locs);
	int	(*set_rxnfc)(struct dsa_switch *ds, int port,
			     struct ethtool_rxnfc *nfc);

	/*
	 * TC integration
	 */
	int	(*port_mirror_add)(struct dsa_switch *ds, int port,
				   struct dsa_mall_mirror_tc_entry *mirror,
				   bool ingress);
	void	(*port_mirror_del)(struct dsa_switch *ds, int port,
				   struct dsa_mall_mirror_tc_entry *mirror);
	int	(*port_setup_tc)(struct dsa_switch *ds, int port,
				 enum tc_setup_type type, void *type_data);

	/*
	 * Cross-chip operations
	 */
	int	(*crosschip_bridge_join)(struct dsa_switch *ds, int sw_index,
					 int port, struct net_device *br);
	void	(*crosschip_bridge_leave)(struct dsa_switch *ds, int sw_index,
					  int port, struct net_device *br);

	/*
	 * PTP functionality
	 */
	int	(*port_hwtstamp_get)(struct dsa_switch *ds, int port,
				     struct ifreq *ifr);
	int	(*port_hwtstamp_set)(struct dsa_switch *ds, int port,
				     struct ifreq *ifr);
	bool	(*port_txtstamp)(struct dsa_switch *ds, int port,
				 struct sk_buff *clone, unsigned int type);
	bool	(*port_rxtstamp)(struct dsa_switch *ds, int port,
				 struct sk_buff *skb, unsigned int type);

	/*
	 * Deferred frame Tx
	 */
	netdev_tx_t (*port_deferred_xmit)(struct dsa_switch *ds, int port,
					  struct sk_buff *skb);
};

struct dsa_switch_driver {
	struct list_head	list;
	const struct dsa_switch_ops *ops;
};

struct net_device *dsa_dev_to_net_device(struct device *dev);

/* Keep inline for faster access in hot path */
static inline bool netdev_uses_dsa(struct net_device *dev)
{
#if IS_ENABLED(CONFIG_NET_DSA)
	return dev->dsa_ptr && dev->dsa_ptr->rcv;
#endif
	return false;
}

static inline bool dsa_can_decode(const struct sk_buff *skb,
				  struct net_device *dev)
{
#if IS_ENABLED(CONFIG_NET_DSA)
	return !dev->dsa_ptr->filter || dev->dsa_ptr->filter(skb, dev);
#endif
	return false;
}

struct dsa_switch *dsa_switch_alloc(struct device *dev, size_t n);
void dsa_unregister_switch(struct dsa_switch *ds);
int dsa_register_switch(struct dsa_switch *ds);
#ifdef CONFIG_PM_SLEEP
int dsa_switch_suspend(struct dsa_switch *ds);
int dsa_switch_resume(struct dsa_switch *ds);
#else
static inline int dsa_switch_suspend(struct dsa_switch *ds)
{
	return 0;
}
static inline int dsa_switch_resume(struct dsa_switch *ds)
{
	return 0;
}
#endif /* CONFIG_PM_SLEEP */

enum dsa_notifier_type {
	DSA_PORT_REGISTER,
	DSA_PORT_UNREGISTER,
};

struct dsa_notifier_info {
	struct net_device *dev;
};

struct dsa_notifier_register_info {
	struct dsa_notifier_info info;	/* must be first */
	struct net_device *master;
	unsigned int port_number;
	unsigned int switch_number;
};

static inline struct net_device *
dsa_notifier_info_to_dev(const struct dsa_notifier_info *info)
{
	return info->dev;
}

#if IS_ENABLED(CONFIG_NET_DSA)
int register_dsa_notifier(struct notifier_block *nb);
int unregister_dsa_notifier(struct notifier_block *nb);
int call_dsa_notifiers(unsigned long val, struct net_device *dev,
		       struct dsa_notifier_info *info);
#else
static inline int register_dsa_notifier(struct notifier_block *nb)
{
	return 0;
}

static inline int unregister_dsa_notifier(struct notifier_block *nb)
{
	return 0;
}

static inline int call_dsa_notifiers(unsigned long val, struct net_device *dev,
				     struct dsa_notifier_info *info)
{
	return NOTIFY_DONE;
}
#endif

/* Broadcom tag specific helpers to insert and extract queue/port number */
#define BRCM_TAG_SET_PORT_QUEUE(p, q)	((p) << 8 | q)
#define BRCM_TAG_GET_PORT(v)		((v) >> 8)
#define BRCM_TAG_GET_QUEUE(v)		((v) & 0xff)


netdev_tx_t dsa_enqueue_skb(struct sk_buff *skb, struct net_device *dev);
int dsa_port_get_phy_strings(struct dsa_port *dp, uint8_t *data);
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