ath9k/ath: move dfs pattern detector to ath

Move the DFS pattern detector code to the ath module so
the other Atheros drivers can make us of it. This makes
no functional changes.

Signed-off-by: Janusz Dziedzic <janusz.dziedzic@tieto.com>
Reviewed-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 429 insertions, 0 deletions

diff --git a/drivers/net/wireless/ath/dfs_pri_detector.c b/drivers/net/wireless/ath/dfs_pri_detector.c
new file mode 100644
index 000000000000..43b608178884
--- /dev/null
+++ b/drivers/net/wireless/ath/dfs_pri_detector.c
@@ -0,0 +1,429 @@
+/*
+ * 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 "ath.h"
+#include "dfs_pattern_detector.h"
+#include "dfs_pri_detector.h"
+
+struct ath_dfs_pool_stats global_dfs_pool_stats = {};
+
+#define DFS_POOL_STAT_INC(c) (global_dfs_pool_stats.c++)
+#define DFS_POOL_STAT_DEC(c) (global_dfs_pool_stats.c--)
+
+/**
+ * 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_ATOMIC);
+		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_ATOMIC);
+			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 struct pri_sequence *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 NULL;
+
+	if ((ts - de->last_ts) < rs->max_pri_tolerance)
+		/* if delta to last pulse is too short, don't use this pulse */
+		return NULL;
+	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)) {
+		pri_detector_reset(de, ts);
+		return NULL;
+	}
+
+	ps = pseq_handler_check_detection(de);
+
+	if (ps == NULL)
+		pulse_queue_enqueue(de, ts);
+
+	return ps;
+}
+
+struct pri_detector *pri_detector_init(const struct radar_detector_specs *rs)
+{
+	struct pri_detector *de;
+
+	de = kzalloc(sizeof(*de), GFP_ATOMIC);
+	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;
+}