/*
 * Copyright(c) 2019-2021 Intel Corporation
 * Copyright(c) 2023-2025 Huawei Technologies Co., Ltd.
 * SPDX-License-Identifier: BSD-3-Clause
 */

#ifndef __OCF_ENV_REFCNT_H__
#define __OCF_ENV_REFCNT_H__

#include "ocf_env.h"

typedef void (*env_refcnt_cb_t)(void *priv);

struct env_refcnt_pcpu {
	env_atomic64 counter;
	bool freeze;
};

typedef void (*env_refcnt_do_on_cpu_cb_t)(void *priv);

struct notify_cpu_work {
	struct work_struct work;

	/* function to call on each cpu */
	env_refcnt_do_on_cpu_cb_t cb;

	/* priv passed to cb */
	void *priv;

	/* refcnt instance */
	struct env_refcnt *rc;
};

struct env_refcnt {
	struct env_refcnt_pcpu __percpu *pcpu __aligned(64);

	struct {
		/* freeze counter */
		int counter;

		/* global counter used instead of per-CPU ones after
		 * freeze
		 */
		env_atomic64 countdown;

		/* freeze initializing - freeze was requested but not all
		 * CPUs were notified.
		 */
		bool initializing;

		env_spinlock lock;
	} freeze;

	struct {
		struct notify_cpu_work **notify_work_items;
		env_atomic to_notify;
		wait_queue_head_t notify_wait_queue;
		struct workqueue_struct *notify_work_queue;
	} notify;

	struct {
		env_atomic armed;
		env_refcnt_cb_t pfn;
		void *priv;
	} callback;

	char name[32];
};

/* Initialize reference counter */
int env_refcnt_init(struct env_refcnt *rc, const char *name, size_t name_len);

void env_refcnt_deinit(struct env_refcnt *rc);

/* Try to increment counter. Returns counter value (> 0) if successful, 0
 * if counter is frozen
 */
bool env_refcnt_inc(struct env_refcnt  *rc);

/* Decrement reference counter */
void env_refcnt_dec(struct env_refcnt *rc);

/* Disallow incrementing of underlying counter - attempts to increment counter
 * will be failing until env_refcnt_unfreeze is called.
 * It's ok to call freeze multiple times, in which case counter is frozen
 * until all freeze calls are offset by a corresponding unfreeze.
 */
void env_refcnt_freeze(struct env_refcnt *rc);

/* Cancel the effect of single env_refcnt_freeze call */
void env_refcnt_unfreeze(struct env_refcnt *rc);

bool env_refcnt_frozen(struct env_refcnt *rc);

bool env_refcnt_zeroed(struct env_refcnt *rc);

/* Register callback to be called when reference counter drops to 0.
 * Must be called after counter is frozen.
 * Cannot be called until previously regsitered callback had fired.
 */
void env_refcnt_register_zero_cb(struct env_refcnt *rc, env_refcnt_cb_t cb,
		void *priv);

#endif // __OCF_ENV_REFCNT_H__