/* SPDX-License-Identifier: GPL-2.0 */

  #ifndef WB_THROTTLE_H
  #define WB_THROTTLE_H
  
  #include <linux/kernel.h>
  #include <linux/atomic.h>
  #include <linux/wait.h>
  #include <linux/timer.h>
  #include <linux/ktime.h>
  
  #include "blk-stat.h"

  #include "blk-rq-qos.h"

  
  enum wbt_flags {
  	WBT_TRACKED		= 1,	/* write, tracked for throttling */
  	WBT_READ		= 2,	/* read */
  	WBT_KSWAPD		= 4,	/* write, from kswapd */

  	WBT_DISCARD		= 8,	/* discard */

  	WBT_NR_BITS		= 4,	/* number of bits */

  };
  
  enum {

  	WBT_RWQ_BG		= 0,
  	WBT_RWQ_KSWAPD,

  	WBT_RWQ_DISCARD,

  	WBT_NUM_RWQ,

  };

  /*
   * Enable states. Either off, or on by default (done at init time),
   * or on through manual setup in sysfs.
   */
  enum {
  	WBT_STATE_ON_DEFAULT	= 1,
  	WBT_STATE_ON_MANUAL	= 2,
  };

  struct rq_wb {
  	/*
  	 * Settings that govern how we throttle
  	 */
  	unsigned int wb_background;		/* background writeback */
  	unsigned int wb_normal;			/* normal writeback */

  	short enable_state;			/* WBT_STATE_* */

  	/*
  	 * Number of consecutive periods where we don't have enough
  	 * information to make a firm scale up/down decision.
  	 */
  	unsigned int unknown_cnt;
  
  	u64 win_nsec;				/* default window size */
  	u64 cur_win_nsec;			/* current window size */

  	struct blk_stat_callback *cb;

  	u64 sync_issue;

  	void *sync_cookie;
  
  	unsigned int wc;

  
  	unsigned long last_issue;		/* last non-throttled issue */
  	unsigned long last_comp;		/* last non-throttled comp */
  	unsigned long min_lat_nsec;

  	struct rq_qos rqos;

  	struct rq_wait rq_wait[WBT_NUM_RWQ];

  	struct rq_depth rq_depth;

  };

  static inline struct rq_wb *RQWB(struct rq_qos *rqos)
  {
  	return container_of(rqos, struct rq_wb, rqos);
  }

  static inline unsigned int wbt_inflight(struct rq_wb *rwb)
  {
  	unsigned int i, ret = 0;
  
  	for (i = 0; i < WBT_NUM_RWQ; i++)
  		ret += atomic_read(&rwb->rq_wait[i].inflight);
  
  	return ret;
  }

  #ifdef CONFIG_BLK_WBT

  int wbt_init(struct request_queue *);

  void wbt_update_limits(struct request_queue *);

  void wbt_disable_default(struct request_queue *);

  void wbt_enable_default(struct request_queue *);

  u64 wbt_get_min_lat(struct request_queue *q);
  void wbt_set_min_lat(struct request_queue *q, u64 val);

  void wbt_set_write_cache(struct request_queue *, bool);

  u64 wbt_default_latency_nsec(struct request_queue *);

  #else

  static inline void wbt_track(struct request *rq, enum wbt_flags flags)

  {
  }

  static inline int wbt_init(struct request_queue *q)

  {
  	return -EINVAL;
  }

  static inline void wbt_update_limits(struct request_queue *q)

  {
  }

  static inline void wbt_disable_default(struct request_queue *q)

  {
  }

  static inline void wbt_enable_default(struct request_queue *q)

  {
  }

  static inline void wbt_set_write_cache(struct request_queue *q, bool wc)

  {
  }

  static inline u64 wbt_get_min_lat(struct request_queue *q)

  {

  	return 0;

  }

  static inline void wbt_set_min_lat(struct request_queue *q, u64 val)

  {
  }

  static inline u64 wbt_default_latency_nsec(struct request_queue *q)
  {
  	return 0;
  }

  
  #endif /* CONFIG_BLK_WBT */
  
  #endif