1/*
2 * Copyright (c) 2012 Neratec Solutions AG
3 *
4 * Permission to use, copy, modify, and/or distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15 */
16
17#include <linux/slab.h>
18#include <linux/spinlock.h>
19
20#include "ath.h"
21#include "dfs_pattern_detector.h"
22#include "dfs_pri_detector.h"
23
24struct ath_dfs_pool_stats global_dfs_pool_stats = {};
25
26#define DFS_POOL_STAT_INC(c) (global_dfs_pool_stats.c++)
27#define DFS_POOL_STAT_DEC(c) (global_dfs_pool_stats.c--)
28#define GET_PRI_TO_USE(MIN, MAX, RUNTIME) \
29	(MIN + PRI_TOLERANCE == MAX - PRI_TOLERANCE ? \
30	MIN + PRI_TOLERANCE : RUNTIME)
31
32/*
33 * struct pulse_elem - elements in pulse queue
34 */
35struct pulse_elem {
36	struct list_head head;
37	u64 ts;
38};
39
40/*
41 * pde_get_multiple() - get number of multiples considering a given tolerance
42 * Return value: factor if abs(val - factor*fraction) <= tolerance, 0 otherwise
43 */
44static u32 pde_get_multiple(u32 val, u32 fraction, u32 tolerance)
45{
46	u32 remainder;
47	u32 factor;
48	u32 delta;
49
50	if (fraction == 0)
51		return 0;
52
53	delta = (val < fraction) ? (fraction - val) : (val - fraction);
54
55	if (delta <= tolerance)
56		/* val and fraction are within tolerance */
57		return 1;
58
59	factor = val / fraction;
60	remainder = val % fraction;
61	if (remainder > tolerance) {
62		/* no exact match */
63		if ((fraction - remainder) <= tolerance)
64			/* remainder is within tolerance */
65			factor++;
66		else
67			factor = 0;
68	}
69	return factor;
70}
71
72/*
73 * DOC: Singleton Pulse and Sequence Pools
74 *
75 * Instances of pri_sequence and pulse_elem are kept in singleton pools to
76 * reduce the number of dynamic allocations. They are shared between all
77 * instances and grow up to the peak number of simultaneously used objects.
78 *
79 * Memory is freed after all references to the pools are released.
80 */
81static u32 singleton_pool_references;
82static LIST_HEAD(pulse_pool);
83static LIST_HEAD(pseq_pool);
84static DEFINE_SPINLOCK(pool_lock);
85
86static void pool_register_ref(void)
87{
88	spin_lock_bh(&pool_lock);
89	singleton_pool_references++;
90	DFS_POOL_STAT_INC(pool_reference);
91	spin_unlock_bh(&pool_lock);
92}
93
94static void pool_deregister_ref(void)
95{
96	spin_lock_bh(&pool_lock);
97	singleton_pool_references--;
98	DFS_POOL_STAT_DEC(pool_reference);
99	if (singleton_pool_references == 0) {
100		/* free singleton pools with no references left */
101		struct pri_sequence *ps, *ps0;
102		struct pulse_elem *p, *p0;
103
104		list_for_each_entry_safe(p, p0, &pulse_pool, head) {
105			list_del(&p->head);
106			DFS_POOL_STAT_DEC(pulse_allocated);
107			kfree(p);
108		}
109		list_for_each_entry_safe(ps, ps0, &pseq_pool, head) {
110			list_del(&ps->head);
111			DFS_POOL_STAT_DEC(pseq_allocated);
112			kfree(ps);
113		}
114	}
115	spin_unlock_bh(&pool_lock);
116}
117
118static void pool_put_pulse_elem(struct pulse_elem *pe)
119{
120	spin_lock_bh(&pool_lock);
121	list_add(&pe->head, &pulse_pool);
122	DFS_POOL_STAT_DEC(pulse_used);
123	spin_unlock_bh(&pool_lock);
124}
125
126static void pool_put_pseq_elem(struct pri_sequence *pse)
127{
128	spin_lock_bh(&pool_lock);
129	list_add(&pse->head, &pseq_pool);
130	DFS_POOL_STAT_DEC(pseq_used);
131	spin_unlock_bh(&pool_lock);
132}
133
134static struct pri_sequence *pool_get_pseq_elem(void)
135{
136	struct pri_sequence *pse = NULL;
137	spin_lock_bh(&pool_lock);
138	if (!list_empty(&pseq_pool)) {
139		pse = list_first_entry(&pseq_pool, struct pri_sequence, head);
140		list_del(&pse->head);
141		DFS_POOL_STAT_INC(pseq_used);
142	}
143	spin_unlock_bh(&pool_lock);
144	return pse;
145}
146
147static struct pulse_elem *pool_get_pulse_elem(void)
148{
149	struct pulse_elem *pe = NULL;
150	spin_lock_bh(&pool_lock);
151	if (!list_empty(&pulse_pool)) {
152		pe = list_first_entry(&pulse_pool, struct pulse_elem, head);
153		list_del(&pe->head);
154		DFS_POOL_STAT_INC(pulse_used);
155	}
156	spin_unlock_bh(&pool_lock);
157	return pe;
158}
159
160static struct pulse_elem *pulse_queue_get_tail(struct pri_detector *pde)
161{
162	struct list_head *l = &pde->pulses;
163	if (list_empty(l))
164		return NULL;
165	return list_entry(l->prev, struct pulse_elem, head);
166}
167
168static bool pulse_queue_dequeue(struct pri_detector *pde)
169{
170	struct pulse_elem *p = pulse_queue_get_tail(pde);
171	if (p != NULL) {
172		list_del_init(&p->head);
173		pde->count--;
174		/* give it back to pool */
175		pool_put_pulse_elem(p);
176	}
177	return (pde->count > 0);
178}
179
180/* remove pulses older than window */
181static void pulse_queue_check_window(struct pri_detector *pde)
182{
183	u64 min_valid_ts;
184	struct pulse_elem *p;
185
186	/* there is no delta time with less than 2 pulses */
187	if (pde->count < 2)
188		return;
189
190	if (pde->last_ts <= pde->window_size)
191		return;
192
193	min_valid_ts = pde->last_ts - pde->window_size;
194	while ((p = pulse_queue_get_tail(pde)) != NULL) {
195		if (p->ts >= min_valid_ts)
196			return;
197		pulse_queue_dequeue(pde);
198	}
199}
200
201static bool pulse_queue_enqueue(struct pri_detector *pde, u64 ts)
202{
203	struct pulse_elem *p = pool_get_pulse_elem();
204	if (p == NULL) {
205		p = kmalloc(sizeof(*p), GFP_ATOMIC);
206		if (p == NULL) {
207			DFS_POOL_STAT_INC(pulse_alloc_error);
208			return false;
209		}
210		DFS_POOL_STAT_INC(pulse_allocated);
211		DFS_POOL_STAT_INC(pulse_used);
212	}
213	INIT_LIST_HEAD(&p->head);
214	p->ts = ts;
215	list_add(&p->head, &pde->pulses);
216	pde->count++;
217	pde->last_ts = ts;
218	pulse_queue_check_window(pde);
219	if (pde->count >= pde->max_count)
220		pulse_queue_dequeue(pde);
221	return true;
222}
223
224static bool pseq_handler_create_sequences(struct pri_detector *pde,
225					  u64 ts, u32 min_count)
226{
227	struct pulse_elem *p;
228	list_for_each_entry(p, &pde->pulses, head) {
229		struct pri_sequence ps, *new_ps;
230		struct pulse_elem *p2;
231		u32 tmp_false_count;
232		u64 min_valid_ts;
233		u32 delta_ts = ts - p->ts;
234
235		if (delta_ts < pde->rs->pri_min)
236			/* ignore too small pri */
237			continue;
238
239		if (delta_ts > pde->rs->pri_max)
240			/* stop on too large pri (sorted list) */
241			break;
242
243		/* build a new sequence with new potential pri */
244		ps.count = 2;
245		ps.count_falses = 0;
246		ps.first_ts = p->ts;
247		ps.last_ts = ts;
248		ps.pri = GET_PRI_TO_USE(pde->rs->pri_min,
249			pde->rs->pri_max, ts - p->ts);
250		ps.dur = ps.pri * (pde->rs->ppb - 1)
251				+ 2 * pde->rs->max_pri_tolerance;
252
253		p2 = p;
254		tmp_false_count = 0;
255		min_valid_ts = ts - ps.dur;
256		/* check which past pulses are candidates for new sequence */
257		list_for_each_entry_continue(p2, &pde->pulses, head) {
258			u32 factor;
259			if (p2->ts < min_valid_ts)
260				/* stop on crossing window border */
261				break;
262			/* check if pulse match (multi)PRI */
263			factor = pde_get_multiple(ps.last_ts - p2->ts, ps.pri,
264						  pde->rs->max_pri_tolerance);
265			if (factor > 0) {
266				ps.count++;
267				ps.first_ts = p2->ts;
268				/*
269				 * on match, add the intermediate falses
270				 * and reset counter
271				 */
272				ps.count_falses += tmp_false_count;
273				tmp_false_count = 0;
274			} else {
275				/* this is a potential false one */
276				tmp_false_count++;
277			}
278		}
279		if (ps.count <= min_count)
280			/* did not reach minimum count, drop sequence */
281			continue;
282
283		/* this is a valid one, add it */
284		ps.deadline_ts = ps.first_ts + ps.dur;
285		new_ps = pool_get_pseq_elem();
286		if (new_ps == NULL) {
287			new_ps = kmalloc(sizeof(*new_ps), GFP_ATOMIC);
288			if (new_ps == NULL) {
289				DFS_POOL_STAT_INC(pseq_alloc_error);
290				return false;
291			}
292			DFS_POOL_STAT_INC(pseq_allocated);
293			DFS_POOL_STAT_INC(pseq_used);
294		}
295		memcpy(new_ps, &ps, sizeof(ps));
296		INIT_LIST_HEAD(&new_ps->head);
297		list_add(&new_ps->head, &pde->sequences);
298	}
299	return true;
300}
301
302/* check new ts and add to all matching existing sequences */
303static u32
304pseq_handler_add_to_existing_seqs(struct pri_detector *pde, u64 ts)
305{
306	u32 max_count = 0;
307	struct pri_sequence *ps, *ps2;
308	list_for_each_entry_safe(ps, ps2, &pde->sequences, head) {
309		u32 delta_ts;
310		u32 factor;
311
312		/* first ensure that sequence is within window */
313		if (ts > ps->deadline_ts) {
314			list_del_init(&ps->head);
315			pool_put_pseq_elem(ps);
316			continue;
317		}
318
319		delta_ts = ts - ps->last_ts;
320		factor = pde_get_multiple(delta_ts, ps->pri,
321					  pde->rs->max_pri_tolerance);
322		if (factor > 0) {
323			ps->last_ts = ts;
324			ps->count++;
325
326			if (max_count < ps->count)
327				max_count = ps->count;
328		} else {
329			ps->count_falses++;
330		}
331	}
332	return max_count;
333}
334
335static struct pri_sequence *
336pseq_handler_check_detection(struct pri_detector *pde)
337{
338	struct pri_sequence *ps;
339
340	if (list_empty(&pde->sequences))
341		return NULL;
342
343	list_for_each_entry(ps, &pde->sequences, head) {
344		/*
345		 * we assume to have enough matching confidence if we
346		 * 1) have enough pulses
347		 * 2) have more matching than false pulses
348		 */
349		if ((ps->count >= pde->rs->ppb_thresh) &&
350		    (ps->count * pde->rs->num_pri >= ps->count_falses))
351			return ps;
352	}
353	return NULL;
354}
355
356
357/* free pulse queue and sequences list and give objects back to pools */
358static void pri_detector_reset(struct pri_detector *pde, u64 ts)
359{
360	struct pri_sequence *ps, *ps0;
361	struct pulse_elem *p, *p0;
362	list_for_each_entry_safe(ps, ps0, &pde->sequences, head) {
363		list_del_init(&ps->head);
364		pool_put_pseq_elem(ps);
365	}
366	list_for_each_entry_safe(p, p0, &pde->pulses, head) {
367		list_del_init(&p->head);
368		pool_put_pulse_elem(p);
369	}
370	pde->count = 0;
371	pde->last_ts = ts;
372}
373
374static void pri_detector_exit(struct pri_detector *de)
375{
376	pri_detector_reset(de, 0);
377	pool_deregister_ref();
378	kfree(de);
379}
380
381static struct pri_sequence *pri_detector_add_pulse(struct pri_detector *de,
382						   struct pulse_event *event)
383{
384	u32 max_updated_seq;
385	struct pri_sequence *ps;
386	u64 ts = event->ts;
387	const struct radar_detector_specs *rs = de->rs;
388
389	/* ignore pulses not within width range */
390	if ((rs->width_min > event->width) || (rs->width_max < event->width))
391		return NULL;
392
393	if ((ts - de->last_ts) < rs->max_pri_tolerance)
394		/* if delta to last pulse is too short, don't use this pulse */
395		return NULL;
396	/* radar detector spec needs chirp, but not detected */
397	if (rs->chirp && rs->chirp != event->chirp)
398		return NULL;
399
400	de->last_ts = ts;
401
402	max_updated_seq = pseq_handler_add_to_existing_seqs(de, ts);
403
404	if (!pseq_handler_create_sequences(de, ts, max_updated_seq)) {
405		pri_detector_reset(de, ts);
406		return NULL;
407	}
408
409	ps = pseq_handler_check_detection(de);
410
411	if (ps == NULL)
412		pulse_queue_enqueue(de, ts);
413
414	return ps;
415}
416
417struct pri_detector *pri_detector_init(const struct radar_detector_specs *rs)
418{
419	struct pri_detector *de;
420
421	de = kzalloc(sizeof(*de), GFP_ATOMIC);
422	if (de == NULL)
423		return NULL;
424	de->exit = pri_detector_exit;
425	de->add_pulse = pri_detector_add_pulse;
426	de->reset = pri_detector_reset;
427
428	INIT_LIST_HEAD(&de->sequences);
429	INIT_LIST_HEAD(&de->pulses);
430	de->window_size = rs->pri_max * rs->ppb * rs->num_pri;
431	de->max_count = rs->ppb * 2;
432	de->rs = rs;
433
434	pool_register_ref();
435	return de;
436}
437