/*
   * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  #ifndef __RC_MINSTREL_H
  #define __RC_MINSTREL_H

  #define EWMA_LEVEL	96	/* ewma weighting factor [/EWMA_DIV] */
  #define EWMA_DIV	128

  #define SAMPLE_COLUMNS	10	/* number of columns in sample table */

  /* scaled fraction values */

  #define MINSTREL_SCALE  12

  #define MINSTREL_FRAC(val, div) (((val) << MINSTREL_SCALE) / div)
  #define MINSTREL_TRUNC(val) ((val) >> MINSTREL_SCALE)

  /* number of highest throughput rates to consider*/
  #define MAX_THR_RATES 4

  /*
   * Perform EWMA (Exponentially Weighted Moving Average) calculation

   */

  static inline int
  minstrel_ewma(int old, int new, int weight)
  {

  	int diff, incr;
  
  	diff = new - old;
  	incr = (EWMA_DIV - weight) * diff / EWMA_DIV;
  
  	return old + incr;

  }

  /*

   * Perform EWMV (Exponentially Weighted Moving Variance) calculation

   */
  static inline int

  minstrel_ewmv(int old_ewmv, int cur_prob, int prob_ewma, int weight)

  {

  	int diff, incr;

  	diff = cur_prob - prob_ewma;

  	incr = (EWMA_DIV - weight) * diff / EWMA_DIV;

  	return weight * (old_ewmv + MINSTREL_TRUNC(diff * incr)) / EWMA_DIV;

  }

  struct minstrel_rate_stats {
  	/* current / last sampling period attempts/success counters */

  	u16 attempts, last_attempts;
  	u16 success, last_success;

  
  	/* total attempts/success counters */

  	u32 att_hist, succ_hist;

  	/* statistis of packet delivery probability

  	 *  prob_ewma - exponential weighted moving average of prob
  	 *  prob_ewmsd - exp. weighted moving standard deviation of prob */

  	u16 prob_ewma;

  	u16 prob_ewmv;

  
  	/* maximum retry counts */

  	u8 retry_count;
  	u8 retry_count_rtscts;

  
  	u8 sample_skipped;
  	bool retry_updated;
  };

  struct minstrel_rate {
  	int bitrate;

  
  	s8 rix;
  	u8 retry_count_cts;
  	u8 adjusted_retry_count;

  
  	unsigned int perfect_tx_time;
  	unsigned int ack_time;

  	int sample_limit;

  	struct minstrel_rate_stats stats;

  };
  
  struct minstrel_sta_info {

  	struct ieee80211_sta *sta;

  	unsigned long last_stats_update;

  	unsigned int sp_ack_dur;
  	unsigned int rate_avg;
  
  	unsigned int lowest_rix;

  	u8 max_tp_rate[MAX_THR_RATES];
  	u8 max_prob_rate;

  	unsigned int total_packets;
  	unsigned int sample_packets;

  	int sample_deferred;

  	unsigned int sample_row;

  	unsigned int sample_column;
  
  	int n_rates;
  	struct minstrel_rate *r;

  	bool prev_sample;

  
  	/* sampling table */
  	u8 *sample_table;
  
  #ifdef CONFIG_MAC80211_DEBUGFS
  	struct dentry *dbg_stats;

  	struct dentry *dbg_stats_csv;

  #endif
  };
  
  struct minstrel_priv {
  	struct ieee80211_hw *hw;
  	bool has_mrr;
  	unsigned int cw_min;
  	unsigned int cw_max;
  	unsigned int max_retry;

  	unsigned int segment_size;
  	unsigned int update_interval;
  	unsigned int lookaround_rate;
  	unsigned int lookaround_rate_mrr;

  	u8 cck_rates[4];

  #ifdef CONFIG_MAC80211_DEBUGFS
  	/*
  	 * enable fixed rate processing per RC
  	 *   - write static index to debugfs:ieee80211/phyX/rc/fixed_rate_idx
  	 *   - write -1 to enable RC processing again
  	 *   - setting will be applied on next update
  	 */
  	u32 fixed_rate_idx;
  	struct dentry *dbg_fixed_rate;
  #endif

  };

  struct minstrel_debugfs_info {
  	size_t len;
  	char buf[];
  };

  /* Get EWMSD (Exponentially Weighted Moving Standard Deviation) * 10 */
  static inline int
  minstrel_get_ewmsd10(struct minstrel_rate_stats *mrs)
  {
  	unsigned int ewmv = mrs->prob_ewmv;
  	return int_sqrt(MINSTREL_TRUNC(ewmv * 1000 * 1000));
  }

  extern const struct rate_control_ops mac80211_minstrel;

  void minstrel_add_sta_debugfs(void *priv, void *priv_sta, struct dentry *dir);
  void minstrel_remove_sta_debugfs(void *priv, void *priv_sta);

  /* Recalculate success probabilities and counters for a given rate using EWMA */

  void minstrel_calc_rate_stats(struct minstrel_rate_stats *mrs);

  int minstrel_get_tp_avg(struct minstrel_rate *mr, int prob_ewma);

  /* debugfs */
  int minstrel_stats_open(struct inode *inode, struct file *file);

  int minstrel_stats_csv_open(struct inode *inode, struct file *file);

  ssize_t minstrel_stats_read(struct file *file, char __user *buf, size_t len, loff_t *ppos);
  int minstrel_stats_release(struct inode *inode, struct file *file);

  #endif