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