drivers/net/wireless/ath/ath9k/dfs_pri_detector.c - maze/linux - Git at Google

 /*
  * Copyright (c) 2012 Neratec Solutions AG
  *
  * Permission to use, copy, modify, and/or distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
  * copyright notice and this permission notice appear in all copies.
  *
  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */

 #include <linux/slab.h>
 #include <linux/spinlock.h>

 #include "ath9k.h"
 #include "dfs_pattern_detector.h"
 #include "dfs_pri_detector.h"
 #include "dfs_debug.h"

 /**
  * struct pri_sequence - sequence of pulses matching one PRI
  * @head: list_head
  * @pri: pulse repetition interval (PRI) in usecs
  * @dur: duration of sequence in usecs
  * @count: number of pulses in this sequence
  * @count_falses: number of not matching pulses in this sequence
  * @first_ts: time stamp of first pulse in usecs
  * @last_ts: time stamp of last pulse in usecs
  * @deadline_ts: deadline when this sequence becomes invalid (first_ts + dur)
  */
 struct pri_sequence {
 	struct list_head head;
 	u32 pri;
 	u32 dur;
 	u32 count;
 	u32 count_falses;
 	u64 first_ts;
 	u64 last_ts;
 	u64 deadline_ts;
 };

 /**
  * struct pulse_elem - elements in pulse queue
  * @ts: time stamp in usecs
  */
 struct pulse_elem {
 	struct list_head head;
 	u64 ts;
 };

 /**
  * pde_get_multiple() - get number of multiples considering a given tolerance
  * @return factor if abs(val - factor*fraction) <= tolerance, 0 otherwise
  */
 static u32 pde_get_multiple(u32 val, u32 fraction, u32 tolerance)
 {
 	u32 remainder;
 	u32 factor;
 	u32 delta;

 	if (fraction == 0)
 		return 0;

 	delta = (val < fraction) ? (fraction - val) : (val - fraction);

 	if (delta <= tolerance)
 		/* val and fraction are within tolerance */
 		return 1;

 	factor = val / fraction;
 	remainder = val % fraction;
 	if (remainder > tolerance) {
 		/* no exact match */
 		if ((fraction - remainder) <= tolerance)
 			/* remainder is within tolerance */
 			factor++;
 		else
 			factor = 0;
 	}
 	return factor;
 }

 /**
  * DOC: Singleton Pulse and Sequence Pools
  *
  * Instances of pri_sequence and pulse_elem are kept in singleton pools to
  * reduce the number of dynamic allocations. They are shared between all
  * instances and grow up to the peak number of simultaneously used objects.
  *
  * Memory is freed after all references to the pools are released.
  */
 static u32 singleton_pool_references;
 static LIST_HEAD(pulse_pool);
 static LIST_HEAD(pseq_pool);
 static DEFINE_SPINLOCK(pool_lock);

 static void pool_register_ref(void)
 {
 	spin_lock_bh(&pool_lock);
 	singleton_pool_references++;
 	DFS_POOL_STAT_INC(pool_reference);
 	spin_unlock_bh(&pool_lock);
 }

 static void pool_deregister_ref(void)
 {
 	spin_lock_bh(&pool_lock);
 	singleton_pool_references--;
 	DFS_POOL_STAT_DEC(pool_reference);
 	if (singleton_pool_references == 0) {
 		/* free singleton pools with no references left */
 		struct pri_sequence *ps, *ps0;
 		struct pulse_elem *p, *p0;

 		list_for_each_entry_safe(p, p0, &pulse_pool, head) {
 			list_del(&p->head);
 			DFS_POOL_STAT_DEC(pulse_allocated);
 			kfree(p);
 		}
 		list_for_each_entry_safe(ps, ps0, &pseq_pool, head) {
 			list_del(&ps->head);
 			DFS_POOL_STAT_DEC(pseq_allocated);
 			kfree(ps);
 		}
 	}
 	spin_unlock_bh(&pool_lock);
 }

 static void pool_put_pulse_elem(struct pulse_elem *pe)
 {
 	spin_lock_bh(&pool_lock);
 	list_add(&pe->head, &pulse_pool);
 	DFS_POOL_STAT_DEC(pulse_used);
 	spin_unlock_bh(&pool_lock);
 }

 static void pool_put_pseq_elem(struct pri_sequence *pse)
 {
 	spin_lock_bh(&pool_lock);
 	list_add(&pse->head, &pseq_pool);
 	DFS_POOL_STAT_DEC(pseq_used);
 	spin_unlock_bh(&pool_lock);
 }

 static struct pri_sequence *pool_get_pseq_elem(void)
 {
 	struct pri_sequence *pse = NULL;
 	spin_lock_bh(&pool_lock);
 	if (!list_empty(&pseq_pool)) {
 		pse = list_first_entry(&pseq_pool, struct pri_sequence, head);
 		list_del(&pse->head);
 		DFS_POOL_STAT_INC(pseq_used);
 	}
 	spin_unlock_bh(&pool_lock);
 	return pse;
 }

 static struct pulse_elem *pool_get_pulse_elem(void)
 {
 	struct pulse_elem *pe = NULL;
 	spin_lock_bh(&pool_lock);
 	if (!list_empty(&pulse_pool)) {
 		pe = list_first_entry(&pulse_pool, struct pulse_elem, head);
 		list_del(&pe->head);
 		DFS_POOL_STAT_INC(pulse_used);
 	}
 	spin_unlock_bh(&pool_lock);
 	return pe;
 }

 static struct pulse_elem *pulse_queue_get_tail(struct pri_detector *pde)
 {
 	struct list_head *l = &pde->pulses;
 	if (list_empty(l))
 		return NULL;
 	return list_entry(l->prev, struct pulse_elem, head);
 }

 static bool pulse_queue_dequeue(struct pri_detector *pde)
 {
 	struct pulse_elem *p = pulse_queue_get_tail(pde);
 	if (p != NULL) {
 		list_del_init(&p->head);
 		pde->count--;
 		/* give it back to pool */
 		pool_put_pulse_elem(p);
 	}
 	return (pde->count > 0);
 }

 /* remove pulses older than window */
 static void pulse_queue_check_window(struct pri_detector *pde)
 {
 	u64 min_valid_ts;
 	struct pulse_elem *p;

 	/* there is no delta time with less than 2 pulses */
 	if (pde->count < 2)
 		return;

 	if (pde->last_ts <= pde->window_size)
 		return;

 	min_valid_ts = pde->last_ts - pde->window_size;
 	while ((p = pulse_queue_get_tail(pde)) != NULL) {
 		if (p->ts >= min_valid_ts)
 			return;
 		pulse_queue_dequeue(pde);
 	}
 }

 static bool pulse_queue_enqueue(struct pri_detector *pde, u64 ts)
 {
 	struct pulse_elem *p = pool_get_pulse_elem();
 	if (p == NULL) {
 		p = kmalloc(sizeof(*p), GFP_KERNEL);
 		if (p == NULL) {
 			DFS_POOL_STAT_INC(pulse_alloc_error);
 			return false;
 		}
 		DFS_POOL_STAT_INC(pulse_allocated);
 		DFS_POOL_STAT_INC(pulse_used);
 	}
 	INIT_LIST_HEAD(&p->head);
 	p->ts = ts;
 	list_add(&p->head, &pde->pulses);
 	pde->count++;
 	pde->last_ts = ts;
 	pulse_queue_check_window(pde);
 	if (pde->count >= pde->max_count)
 		pulse_queue_dequeue(pde);
 	return true;
 }

 static bool pseq_handler_create_sequences(struct pri_detector *pde,
 					  u64 ts, u32 min_count)
 {
 	struct pulse_elem *p;
 	list_for_each_entry(p, &pde->pulses, head) {
 		struct pri_sequence ps, *new_ps;
 		struct pulse_elem *p2;
 		u32 tmp_false_count;
 		u64 min_valid_ts;
 		u32 delta_ts = ts - p->ts;

 		if (delta_ts < pde->rs->pri_min)
 			/* ignore too small pri */
 			continue;

 		if (delta_ts > pde->rs->pri_max)
 			/* stop on too large pri (sorted list) */
 			break;

 		/* build a new sequence with new potential pri */
 		ps.count = 2;
 		ps.count_falses = 0;
 		ps.first_ts = p->ts;
 		ps.last_ts = ts;
 		ps.pri = ts - p->ts;
 		ps.dur = ps.pri * (pde->rs->ppb - 1)
 				+ 2 * pde->rs->max_pri_tolerance;

 		p2 = p;
 		tmp_false_count = 0;
 		min_valid_ts = ts - ps.dur;
 		/* check which past pulses are candidates for new sequence */
 		list_for_each_entry_continue(p2, &pde->pulses, head) {
 			u32 factor;
 			if (p2->ts < min_valid_ts)
 				/* stop on crossing window border */
 				break;
 			/* check if pulse match (multi)PRI */
 			factor = pde_get_multiple(ps.last_ts - p2->ts, ps.pri,
 						  pde->rs->max_pri_tolerance);
 			if (factor > 0) {
 				ps.count++;
 				ps.first_ts = p2->ts;
 				/*
 				 * on match, add the intermediate falses
 				 * and reset counter
 				 */
 				ps.count_falses += tmp_false_count;
 				tmp_false_count = 0;
 			} else {
 				/* this is a potential false one */
 				tmp_false_count++;
 			}
 		}
 		if (ps.count < min_count)
 			/* did not reach minimum count, drop sequence */
 			continue;

 		/* this is a valid one, add it */
 		ps.deadline_ts = ps.first_ts + ps.dur;
 		new_ps = pool_get_pseq_elem();
 		if (new_ps == NULL) {
 			new_ps = kmalloc(sizeof(*new_ps), GFP_KERNEL);
 			if (new_ps == NULL) {
 				DFS_POOL_STAT_INC(pseq_alloc_error);
 				return false;
 			}
 			DFS_POOL_STAT_INC(pseq_allocated);
 			DFS_POOL_STAT_INC(pseq_used);
 		}
 		memcpy(new_ps, &ps, sizeof(ps));
 		INIT_LIST_HEAD(&new_ps->head);
 		list_add(&new_ps->head, &pde->sequences);
 	}
 	return true;
 }

 /* check new ts and add to all matching existing sequences */
 static u32
 pseq_handler_add_to_existing_seqs(struct pri_detector *pde, u64 ts)
 {
 	u32 max_count = 0;
 	struct pri_sequence *ps, *ps2;
 	list_for_each_entry_safe(ps, ps2, &pde->sequences, head) {
 		u32 delta_ts;
 		u32 factor;

 		/* first ensure that sequence is within window */
 		if (ts > ps->deadline_ts) {
 			list_del_init(&ps->head);
 			pool_put_pseq_elem(ps);
 			continue;
 		}

 		delta_ts = ts - ps->last_ts;
 		factor = pde_get_multiple(delta_ts, ps->pri,
 					  pde->rs->max_pri_tolerance);
 		if (factor > 0) {
 			ps->last_ts = ts;
 			ps->count++;

 			if (max_count < ps->count)
 				max_count = ps->count;
 		} else {
 			ps->count_falses++;
 		}
 	}
 	return max_count;
 }

 static struct pri_sequence *
 pseq_handler_check_detection(struct pri_detector *pde)
 {
 	struct pri_sequence *ps;

 	if (list_empty(&pde->sequences))
 		return NULL;

 	list_for_each_entry(ps, &pde->sequences, head) {
 		/*
 		 * we assume to have enough matching confidence if we
 		 * 1) have enough pulses
 		 * 2) have more matching than false pulses
 		 */
 		if ((ps->count >= pde->rs->ppb_thresh) &&
 		    (ps->count * pde->rs->num_pri >= ps->count_falses))
 			return ps;
 	}
 	return NULL;
 }


 /* free pulse queue and sequences list and give objects back to pools */
 static void pri_detector_reset(struct pri_detector *pde, u64 ts)
 {
 	struct pri_sequence *ps, *ps0;
 	struct pulse_elem *p, *p0;
 	list_for_each_entry_safe(ps, ps0, &pde->sequences, head) {
 		list_del_init(&ps->head);
 		pool_put_pseq_elem(ps);
 	}
 	list_for_each_entry_safe(p, p0, &pde->pulses, head) {
 		list_del_init(&p->head);
 		pool_put_pulse_elem(p);
 	}
 	pde->count = 0;
 	pde->last_ts = ts;
 }

 static void pri_detector_exit(struct pri_detector *de)
 {
 	pri_detector_reset(de, 0);
 	pool_deregister_ref();
 	kfree(de);
 }

 static bool pri_detector_add_pulse(struct pri_detector *de,
 				   struct pulse_event *event)
 {
 	u32 max_updated_seq;
 	struct pri_sequence *ps;
 	u64 ts = event->ts;
 	const struct radar_detector_specs *rs = de->rs;

 	/* ignore pulses not within width range */
 	if ((rs->width_min > event->width) || (rs->width_max < event->width))
 		return false;

 	if ((ts - de->last_ts) < rs->max_pri_tolerance)
 		/* if delta to last pulse is too short, don't use this pulse */
 		return false;
 	de->last_ts = ts;

 	max_updated_seq = pseq_handler_add_to_existing_seqs(de, ts);

 	if (!pseq_handler_create_sequences(de, ts, max_updated_seq)) {
 		pr_err("failed to create pulse sequences\n");
 		pri_detector_reset(de, ts);
 		return false;
 	}

 	ps = pseq_handler_check_detection(de);

 	if (ps != NULL) {
 		pr_info("DFS: radar found: pri=%d, count=%d, count_false=%d\n",
 			 ps->pri, ps->count, ps->count_falses);
 		pri_detector_reset(de, ts);
 		return true;
 	}
 	pulse_queue_enqueue(de, ts);
 	return false;
 }

 struct pri_detector *
 pri_detector_init(const struct radar_detector_specs *rs)
 {
 	struct pri_detector *de;
 	de = kzalloc(sizeof(*de), GFP_KERNEL);
 	if (de == NULL)
 		return NULL;
 	de->exit = pri_detector_exit;
 	de->add_pulse = pri_detector_add_pulse;
 	de->reset = pri_detector_reset;

 	INIT_LIST_HEAD(&de->sequences);
 	INIT_LIST_HEAD(&de->pulses);
 	de->window_size = rs->pri_max * rs->ppb * rs->num_pri;
 	de->max_count = rs->ppb * 2;
 	de->rs = rs;

 	pool_register_ref();
 	return de;
 }
	/*
	* Copyright (c) 2012 Neratec Solutions AG
	*
	* Permission to use, copy, modify, and/or distribute this software for any
	* purpose with or without fee is hereby granted, provided that the above
	* copyright notice and this permission notice appear in all copies.
	*
	* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
	* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
	* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
	* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
	*/

	#include <linux/slab.h>
	#include <linux/spinlock.h>

	#include "ath9k.h"
	#include "dfs_pattern_detector.h"
	#include "dfs_pri_detector.h"
	#include "dfs_debug.h"

	/**
	* struct pri_sequence - sequence of pulses matching one PRI
	* @head: list_head
	* @pri: pulse repetition interval (PRI) in usecs
	* @dur: duration of sequence in usecs
	* @count: number of pulses in this sequence
	* @count_falses: number of not matching pulses in this sequence
	* @first_ts: time stamp of first pulse in usecs
	* @last_ts: time stamp of last pulse in usecs
	* @deadline_ts: deadline when this sequence becomes invalid (first_ts + dur)
	*/
	struct pri_sequence {
	struct list_head head;
	u32 pri;
	u32 dur;
	u32 count;
	u32 count_falses;
	u64 first_ts;
	u64 last_ts;
	u64 deadline_ts;
	};

	/**
	* struct pulse_elem - elements in pulse queue
	* @ts: time stamp in usecs
	*/
	struct pulse_elem {
	struct list_head head;
	u64 ts;
	};

	/**
	* pde_get_multiple() - get number of multiples considering a given tolerance
	* @return factor if abs(val - factor*fraction) <= tolerance, 0 otherwise
	*/
	static u32 pde_get_multiple(u32 val, u32 fraction, u32 tolerance)
	{
	u32 remainder;
	u32 factor;
	u32 delta;

	if (fraction == 0)
	return 0;

	delta = (val < fraction) ? (fraction - val) : (val - fraction);

	if (delta <= tolerance)
	/* val and fraction are within tolerance */
	return 1;

	factor = val / fraction;
	remainder = val % fraction;
	if (remainder > tolerance) {
	/* no exact match */
	if ((fraction - remainder) <= tolerance)
	/* remainder is within tolerance */
	factor++;
	else
	factor = 0;
	}
	return factor;
	}

	/**
	* DOC: Singleton Pulse and Sequence Pools
	*
	* Instances of pri_sequence and pulse_elem are kept in singleton pools to
	* reduce the number of dynamic allocations. They are shared between all
	* instances and grow up to the peak number of simultaneously used objects.
	*
	* Memory is freed after all references to the pools are released.
	*/
	static u32 singleton_pool_references;
	static LIST_HEAD(pulse_pool);
	static LIST_HEAD(pseq_pool);
	static DEFINE_SPINLOCK(pool_lock);

	static void pool_register_ref(void)
	{
	spin_lock_bh(&pool_lock);
	singleton_pool_references++;
	DFS_POOL_STAT_INC(pool_reference);
	spin_unlock_bh(&pool_lock);
	}

	static void pool_deregister_ref(void)
	{
	spin_lock_bh(&pool_lock);
	singleton_pool_references--;
	DFS_POOL_STAT_DEC(pool_reference);
	if (singleton_pool_references == 0) {
	/* free singleton pools with no references left */
	struct pri_sequence ps, ps0;
	struct pulse_elem p, p0;

	list_for_each_entry_safe(p, p0, &pulse_pool, head) {
	list_del(&p->head);
	DFS_POOL_STAT_DEC(pulse_allocated);
	kfree(p);
	}
	list_for_each_entry_safe(ps, ps0, &pseq_pool, head) {
	list_del(&ps->head);
	DFS_POOL_STAT_DEC(pseq_allocated);
	kfree(ps);
	}
	}
	spin_unlock_bh(&pool_lock);
	}

	static void pool_put_pulse_elem(struct pulse_elem *pe)
	{
	spin_lock_bh(&pool_lock);
	list_add(&pe->head, &pulse_pool);
	DFS_POOL_STAT_DEC(pulse_used);
	spin_unlock_bh(&pool_lock);
	}

	static void pool_put_pseq_elem(struct pri_sequence *pse)
	{
	spin_lock_bh(&pool_lock);
	list_add(&pse->head, &pseq_pool);
	DFS_POOL_STAT_DEC(pseq_used);
	spin_unlock_bh(&pool_lock);
	}

	static struct pri_sequence *pool_get_pseq_elem(void)
	{
	struct pri_sequence *pse = NULL;
	spin_lock_bh(&pool_lock);
	if (!list_empty(&pseq_pool)) {
	pse = list_first_entry(&pseq_pool, struct pri_sequence, head);
	list_del(&pse->head);
	DFS_POOL_STAT_INC(pseq_used);
	}
	spin_unlock_bh(&pool_lock);
	return pse;
	}

	static struct pulse_elem *pool_get_pulse_elem(void)
	{
	struct pulse_elem *pe = NULL;
	spin_lock_bh(&pool_lock);
	if (!list_empty(&pulse_pool)) {
	pe = list_first_entry(&pulse_pool, struct pulse_elem, head);
	list_del(&pe->head);
	DFS_POOL_STAT_INC(pulse_used);
	}
	spin_unlock_bh(&pool_lock);
	return pe;
	}

	static struct pulse_elem pulse_queue_get_tail(struct pri_detector pde)
	{
	struct list_head *l = &pde->pulses;
	if (list_empty(l))
	return NULL;
	return list_entry(l->prev, struct pulse_elem, head);
	}

	static bool pulse_queue_dequeue(struct pri_detector *pde)
	{
	struct pulse_elem *p = pulse_queue_get_tail(pde);
	if (p != NULL) {
	list_del_init(&p->head);
	pde->count--;
	/* give it back to pool */
	pool_put_pulse_elem(p);
	}
	return (pde->count > 0);
	}

	/* remove pulses older than window */
	static void pulse_queue_check_window(struct pri_detector *pde)
	{
	u64 min_valid_ts;
	struct pulse_elem *p;

	/* there is no delta time with less than 2 pulses */
	if (pde->count < 2)
	return;

	if (pde->last_ts <= pde->window_size)
	return;

	min_valid_ts = pde->last_ts - pde->window_size;
	while ((p = pulse_queue_get_tail(pde)) != NULL) {
	if (p->ts >= min_valid_ts)
	return;
	pulse_queue_dequeue(pde);
	}
	}

	static bool pulse_queue_enqueue(struct pri_detector *pde, u64 ts)
	{
	struct pulse_elem *p = pool_get_pulse_elem();
	if (p == NULL) {
	p = kmalloc(sizeof(*p), GFP_KERNEL);
	if (p == NULL) {
	DFS_POOL_STAT_INC(pulse_alloc_error);
	return false;
	}
	DFS_POOL_STAT_INC(pulse_allocated);
	DFS_POOL_STAT_INC(pulse_used);
	}
	INIT_LIST_HEAD(&p->head);
	p->ts = ts;
	list_add(&p->head, &pde->pulses);
	pde->count++;
	pde->last_ts = ts;
	pulse_queue_check_window(pde);
	if (pde->count >= pde->max_count)
	pulse_queue_dequeue(pde);
	return true;
	}

	static bool pseq_handler_create_sequences(struct pri_detector *pde,
	u64 ts, u32 min_count)
	{
	struct pulse_elem *p;
	list_for_each_entry(p, &pde->pulses, head) {
	struct pri_sequence ps, *new_ps;
	struct pulse_elem *p2;
	u32 tmp_false_count;
	u64 min_valid_ts;
	u32 delta_ts = ts - p->ts;

	if (delta_ts < pde->rs->pri_min)
	/* ignore too small pri */
	continue;

	if (delta_ts > pde->rs->pri_max)
	/* stop on too large pri (sorted list) */
	break;

	/* build a new sequence with new potential pri */
	ps.count = 2;
	ps.count_falses = 0;
	ps.first_ts = p->ts;
	ps.last_ts = ts;
	ps.pri = ts - p->ts;
	ps.dur = ps.pri * (pde->rs->ppb - 1)
	+ 2 * pde->rs->max_pri_tolerance;

	p2 = p;
	tmp_false_count = 0;
	min_valid_ts = ts - ps.dur;
	/* check which past pulses are candidates for new sequence */
	list_for_each_entry_continue(p2, &pde->pulses, head) {
	u32 factor;
	if (p2->ts < min_valid_ts)
	/* stop on crossing window border */
	break;
	/* check if pulse match (multi)PRI */
	factor = pde_get_multiple(ps.last_ts - p2->ts, ps.pri,
	pde->rs->max_pri_tolerance);
	if (factor > 0) {
	ps.count++;
	ps.first_ts = p2->ts;
	/*
	* on match, add the intermediate falses
	* and reset counter
	*/
	ps.count_falses += tmp_false_count;
	tmp_false_count = 0;
	} else {
	/* this is a potential false one */
	tmp_false_count++;
	}
	}
	if (ps.count < min_count)
	/* did not reach minimum count, drop sequence */
	continue;

	/* this is a valid one, add it */
	ps.deadline_ts = ps.first_ts + ps.dur;
	new_ps = pool_get_pseq_elem();
	if (new_ps == NULL) {
	new_ps = kmalloc(sizeof(*new_ps), GFP_KERNEL);
	if (new_ps == NULL) {
	DFS_POOL_STAT_INC(pseq_alloc_error);
	return false;
	}
	DFS_POOL_STAT_INC(pseq_allocated);
	DFS_POOL_STAT_INC(pseq_used);
	}
	memcpy(new_ps, &ps, sizeof(ps));
	INIT_LIST_HEAD(&new_ps->head);
	list_add(&new_ps->head, &pde->sequences);
	}
	return true;
	}

	/* check new ts and add to all matching existing sequences */
	static u32
	pseq_handler_add_to_existing_seqs(struct pri_detector *pde, u64 ts)
	{
	u32 max_count = 0;
	struct pri_sequence ps, ps2;
	list_for_each_entry_safe(ps, ps2, &pde->sequences, head) {
	u32 delta_ts;
	u32 factor;

	/* first ensure that sequence is within window */
	if (ts > ps->deadline_ts) {
	list_del_init(&ps->head);
	pool_put_pseq_elem(ps);
	continue;
	}

	delta_ts = ts - ps->last_ts;
	factor = pde_get_multiple(delta_ts, ps->pri,
	pde->rs->max_pri_tolerance);
	if (factor > 0) {
	ps->last_ts = ts;
	ps->count++;

	if (max_count < ps->count)
	max_count = ps->count;
	} else {
	ps->count_falses++;
	}
	}
	return max_count;
	}

	static struct pri_sequence *
	pseq_handler_check_detection(struct pri_detector *pde)
	{
	struct pri_sequence *ps;

	if (list_empty(&pde->sequences))
	return NULL;

	list_for_each_entry(ps, &pde->sequences, head) {
	/*
	* we assume to have enough matching confidence if we
	* 1) have enough pulses
	* 2) have more matching than false pulses
	*/
	if ((ps->count >= pde->rs->ppb_thresh) &&
	(ps->count * pde->rs->num_pri >= ps->count_falses))
	return ps;
	}
	return NULL;
	}


	/* free pulse queue and sequences list and give objects back to pools */
	static void pri_detector_reset(struct pri_detector *pde, u64 ts)
	{
	struct pri_sequence ps, ps0;
	struct pulse_elem p, p0;
	list_for_each_entry_safe(ps, ps0, &pde->sequences, head) {
	list_del_init(&ps->head);
	pool_put_pseq_elem(ps);
	}
	list_for_each_entry_safe(p, p0, &pde->pulses, head) {
	list_del_init(&p->head);
	pool_put_pulse_elem(p);
	}
	pde->count = 0;
	pde->last_ts = ts;
	}

	static void pri_detector_exit(struct pri_detector *de)
	{
	pri_detector_reset(de, 0);
	pool_deregister_ref();
	kfree(de);
	}

	static bool pri_detector_add_pulse(struct pri_detector *de,
	struct pulse_event *event)
	{
	u32 max_updated_seq;
	struct pri_sequence *ps;
	u64 ts = event->ts;
	const struct radar_detector_specs *rs = de->rs;

	/* ignore pulses not within width range */
	if ((rs->width_min > event->width) \|\| (rs->width_max < event->width))
	return false;

	if ((ts - de->last_ts) < rs->max_pri_tolerance)
	/* if delta to last pulse is too short, don't use this pulse */
	return false;
	de->last_ts = ts;

	max_updated_seq = pseq_handler_add_to_existing_seqs(de, ts);

	if (!pseq_handler_create_sequences(de, ts, max_updated_seq)) {
	pr_err("failed to create pulse sequences\n");
	pri_detector_reset(de, ts);
	return false;
	}

	ps = pseq_handler_check_detection(de);

	if (ps != NULL) {
	pr_info("DFS: radar found: pri=%d, count=%d, count_false=%d\n",
	ps->pri, ps->count, ps->count_falses);
	pri_detector_reset(de, ts);
	return true;
	}
	pulse_queue_enqueue(de, ts);
	return false;
	}

	struct pri_detector *
	pri_detector_init(const struct radar_detector_specs *rs)
	{
	struct pri_detector *de;
	de = kzalloc(sizeof(*de), GFP_KERNEL);
	if (de == NULL)
	return NULL;
	de->exit = pri_detector_exit;
	de->add_pulse = pri_detector_add_pulse;
	de->reset = pri_detector_reset;

	INIT_LIST_HEAD(&de->sequences);
	INIT_LIST_HEAD(&de->pulses);
	de->window_size = rs->pri_max * rs->ppb * rs->num_pri;
	de->max_count = rs->ppb * 2;
	de->rs = rs;

	pool_register_ref();
	return de;
	}