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/export.h>
 19
 20#include "dfs_pattern_detector.h"
 21#include "dfs_pri_detector.h"
 22
 23/*
 24 * tolerated deviation of radar time stamp in usecs on both sides
 25 * TODO: this might need to be HW-dependent
 26 */
 27#define PRI_TOLERANCE	16
 28
 29/**
 30 * struct radar_types - contains array of patterns defined for one DFS domain
 31 * @domain: DFS regulatory domain
 32 * @num_radar_types: number of radar types to follow
 33 * @radar_types: radar types array
 34 */
 35struct radar_types {
 36	enum nl80211_dfs_regions region;
 37	u32 num_radar_types;
 38	const struct radar_detector_specs *radar_types;
 39};
 40
 41/* percentage on ppb threshold to trigger detection */
 42#define MIN_PPB_THRESH	50
 43#define PPB_THRESH(PPB) ((PPB * MIN_PPB_THRESH + 50) / 100)
 44#define PRF2PRI(PRF) ((1000000 + PRF / 2) / PRF)
 45
 46#define ETSI_PATTERN(ID, WMIN, WMAX, PMIN, PMAX, PRF, PPB)	\
 47{								\
 48	ID, WMIN, WMAX, (PRF2PRI(PMAX) - PRI_TOLERANCE),	\
 49	(PRF2PRI(PMIN) * PRF + PRI_TOLERANCE), PRF, PPB * PRF,	\
 50	PPB_THRESH(PPB), PRI_TOLERANCE,				\
 51}
 52
 53/* radar types as defined by ETSI EN-301-893 v1.5.1 */
 54static const struct radar_detector_specs etsi_radar_ref_types_v15[] = {
 55	ETSI_PATTERN(0,  0,  1,  700,  700, 1, 18),
 56	ETSI_PATTERN(1,  0,  5,  200, 1000, 1, 10),
 57	ETSI_PATTERN(2,  0, 15,  200, 1600, 1, 15),
 58	ETSI_PATTERN(3,  0, 15, 2300, 4000, 1, 25),
 59	ETSI_PATTERN(4, 20, 30, 2000, 4000, 1, 20),
 60	ETSI_PATTERN(5,  0,  2,  300,  400, 3, 10),
 61	ETSI_PATTERN(6,  0,  2,  400, 1200, 3, 15),
 62};
 63
 64static const struct radar_types etsi_radar_types_v15 = {
 65	.region			= NL80211_DFS_ETSI,
 66	.num_radar_types	= ARRAY_SIZE(etsi_radar_ref_types_v15),
 67	.radar_types		= etsi_radar_ref_types_v15,
 68};
 69
 70/* for now, we support ETSI radar types, FCC and JP are TODO */
 71static const struct radar_types *dfs_domains[] = {
 72	&etsi_radar_types_v15,
 73};
 74
 75/**
 76 * get_dfs_domain_radar_types() - get radar types for a given DFS domain
 77 * @param domain DFS domain
 78 * @return radar_types ptr on success, NULL if DFS domain is not supported
 79 */
 80static const struct radar_types *
 81get_dfs_domain_radar_types(enum nl80211_dfs_regions region)
 82{
 83	u32 i;
 84	for (i = 0; i < ARRAY_SIZE(dfs_domains); i++) {
 85		if (dfs_domains[i]->region == region)
 86			return dfs_domains[i];
 87	}
 88	return NULL;
 89}
 90
 91/**
 92 * struct channel_detector - detector elements for a DFS channel
 93 * @head: list_head
 94 * @freq: frequency for this channel detector in MHz
 95 * @detectors: array of dynamically created detector elements for this freq
 96 *
 97 * Channel detectors are required to provide multi-channel DFS detection, e.g.
 98 * to support off-channel scanning. A pattern detector has a list of channels
 99 * radar pulses have been reported for in the past.
100 */
101struct channel_detector {
102	struct list_head head;
103	u16 freq;
104	struct pri_detector **detectors;
105};
106
107/* channel_detector_reset() - reset detector lines for a given channel */
108static void channel_detector_reset(struct dfs_pattern_detector *dpd,
109				   struct channel_detector *cd)
110{
111	u32 i;
112	if (cd == NULL)
113		return;
114	for (i = 0; i < dpd->num_radar_types; i++)
115		cd->detectors[i]->reset(cd->detectors[i], dpd->last_pulse_ts);
116}
117
118/* channel_detector_exit() - destructor */
119static void channel_detector_exit(struct dfs_pattern_detector *dpd,
120				  struct channel_detector *cd)
121{
122	u32 i;
123	if (cd == NULL)
124		return;
125	list_del(&cd->head);
126	for (i = 0; i < dpd->num_radar_types; i++) {
127		struct pri_detector *de = cd->detectors[i];
128		if (de != NULL)
129			de->exit(de);
130	}
131	kfree(cd->detectors);
132	kfree(cd);
133}
134
135static struct channel_detector *
136channel_detector_create(struct dfs_pattern_detector *dpd, u16 freq)
137{
138	u32 sz, i;
139	struct channel_detector *cd;
140
141	cd = kmalloc(sizeof(*cd), GFP_KERNEL);
142	if (cd == NULL)
143		goto fail;
144
145	INIT_LIST_HEAD(&cd->head);
146	cd->freq = freq;
147	sz = sizeof(cd->detectors) * dpd->num_radar_types;
148	cd->detectors = kzalloc(sz, GFP_KERNEL);
149	if (cd->detectors == NULL)
150		goto fail;
151
152	for (i = 0; i < dpd->num_radar_types; i++) {
153		const struct radar_detector_specs *rs = &dpd->radar_spec[i];
154		struct pri_detector *de = pri_detector_init(rs);
155		if (de == NULL)
156			goto fail;
157		cd->detectors[i] = de;
158	}
159	list_add(&cd->head, &dpd->channel_detectors);
160	return cd;
161
162fail:
163	pr_err("failed to allocate channel_detector for freq=%d\n", freq);
164	channel_detector_exit(dpd, cd);
165	return NULL;
166}
167
168/**
169 * channel_detector_get() - get channel detector for given frequency
170 * @param dpd instance pointer
171 * @param freq frequency in MHz
172 * @return pointer to channel detector on success, NULL otherwise
173 *
174 * Return existing channel detector for the given frequency or return a
175 * newly create one.
176 */
177static struct channel_detector *
178channel_detector_get(struct dfs_pattern_detector *dpd, u16 freq)
179{
180	struct channel_detector *cd;
181	list_for_each_entry(cd, &dpd->channel_detectors, head) {
182		if (cd->freq == freq)
183			return cd;
184	}
185	return channel_detector_create(dpd, freq);
186}
187
188/*
189 * DFS Pattern Detector
190 */
191
192/* dpd_reset(): reset all channel detectors */
193static void dpd_reset(struct dfs_pattern_detector *dpd)
194{
195	struct channel_detector *cd;
196	if (!list_empty(&dpd->channel_detectors))
197		list_for_each_entry(cd, &dpd->channel_detectors, head)
198			channel_detector_reset(dpd, cd);
199
200}
201static void dpd_exit(struct dfs_pattern_detector *dpd)
202{
203	struct channel_detector *cd, *cd0;
204	if (!list_empty(&dpd->channel_detectors))
205		list_for_each_entry_safe(cd, cd0, &dpd->channel_detectors, head)
206			channel_detector_exit(dpd, cd);
207	kfree(dpd);
208}
209
210static bool
211dpd_add_pulse(struct dfs_pattern_detector *dpd, struct pulse_event *event)
212{
213	u32 i;
214	bool ts_wraparound;
215	struct channel_detector *cd;
216
217	if (dpd->region == NL80211_DFS_UNSET) {
218		/*
219		 * pulses received for a non-supported or un-initialized
220		 * domain are treated as detected radars
221		 */
222		return true;
223	}
224
225	cd = channel_detector_get(dpd, event->freq);
226	if (cd == NULL)
227		return false;
228
229	ts_wraparound = (event->ts < dpd->last_pulse_ts);
230	dpd->last_pulse_ts = event->ts;
231	if (ts_wraparound) {
232		/*
233		 * reset detector on time stamp wraparound
234		 * with monotonic time stamps, this should never happen
235		 */
236		pr_warn("DFS: time stamp wraparound detected, resetting\n");
237		dpd_reset(dpd);
238	}
239	/* do type individual pattern matching */
240	for (i = 0; i < dpd->num_radar_types; i++) {
241		if (cd->detectors[i]->add_pulse(cd->detectors[i], event) != 0) {
242			channel_detector_reset(dpd, cd);
243			return true;
244		}
245	}
246	return false;
247}
248
249static bool dpd_set_domain(struct dfs_pattern_detector *dpd,
250			   enum nl80211_dfs_regions region)
251{
252	const struct radar_types *rt;
253	struct channel_detector *cd, *cd0;
254
255	if (dpd->region == region)
256		return true;
257
258	dpd->region = NL80211_DFS_UNSET;
259
260	rt = get_dfs_domain_radar_types(region);
261	if (rt == NULL)
262		return false;
263
264	/* delete all channel detectors for previous DFS domain */
265	if (!list_empty(&dpd->channel_detectors))
266		list_for_each_entry_safe(cd, cd0, &dpd->channel_detectors, head)
267			channel_detector_exit(dpd, cd);
268	dpd->radar_spec = rt->radar_types;
269	dpd->num_radar_types = rt->num_radar_types;
270
271	dpd->region = region;
272	return true;
273}
274
275static struct dfs_pattern_detector default_dpd = {
276	.exit		= dpd_exit,
277	.set_domain	= dpd_set_domain,
278	.add_pulse	= dpd_add_pulse,
279	.region		= NL80211_DFS_UNSET,
280};
281
282struct dfs_pattern_detector *
283dfs_pattern_detector_init(enum nl80211_dfs_regions region)
284{
285	struct dfs_pattern_detector *dpd;
286	dpd = kmalloc(sizeof(*dpd), GFP_KERNEL);
287	if (dpd == NULL) {
288		pr_err("allocation of dfs_pattern_detector failed\n");
289		return NULL;
290	}
291	*dpd = default_dpd;
292	INIT_LIST_HEAD(&dpd->channel_detectors);
293
294	if (dpd->set_domain(dpd, region))
295		return dpd;
296
297	pr_err("Could not set DFS domain to %d. ", region);
298	return NULL;
299}
300EXPORT_SYMBOL(dfs_pattern_detector_init);