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#include "ath.h"
 23
 24/*
 25 * tolerated deviation of radar time stamp in usecs on both sides
 26 * TODO: this might need to be HW-dependent
 27 */
 28#define PRI_TOLERANCE	16
 29
 30/**
 31 * struct radar_types - contains array of patterns defined for one DFS domain
 32 * @domain: DFS regulatory domain
 33 * @num_radar_types: number of radar types to follow
 34 * @radar_types: radar types array
 35 */
 36struct radar_types {
 37	enum nl80211_dfs_regions region;
 38	u32 num_radar_types;
 39	const struct radar_detector_specs *radar_types;
 40};
 41
 42/* percentage on ppb threshold to trigger detection */
 43#define MIN_PPB_THRESH	50
 44#define PPB_THRESH(PPB) ((PPB * MIN_PPB_THRESH + 50) / 100)
 45#define PRF2PRI(PRF) ((1000000 + PRF / 2) / PRF)
 46/* percentage of pulse width tolerance */
 47#define WIDTH_TOLERANCE 5
 48#define WIDTH_LOWER(X) ((X*(100-WIDTH_TOLERANCE)+50)/100)
 49#define WIDTH_UPPER(X) ((X*(100+WIDTH_TOLERANCE)+50)/100)
 50
 51#define ETSI_PATTERN(ID, WMIN, WMAX, PMIN, PMAX, PRF, PPB)	\
 52{								\
 53	ID, WIDTH_LOWER(WMIN), WIDTH_UPPER(WMAX),		\
 54	(PRF2PRI(PMAX) - PRI_TOLERANCE),			\
 55	(PRF2PRI(PMIN) * PRF + PRI_TOLERANCE), PRF, PPB * PRF,	\
 56	PPB_THRESH(PPB), PRI_TOLERANCE,				\
 57}
 58
 59/* radar types as defined by ETSI EN-301-893 v1.5.1 */
 60static const struct radar_detector_specs etsi_radar_ref_types_v15[] = {
 61	ETSI_PATTERN(0,  0,  1,  700,  700, 1, 18),
 62	ETSI_PATTERN(1,  0,  5,  200, 1000, 1, 10),
 63	ETSI_PATTERN(2,  0, 15,  200, 1600, 1, 15),
 64	ETSI_PATTERN(3,  0, 15, 2300, 4000, 1, 25),
 65	ETSI_PATTERN(4, 20, 30, 2000, 4000, 1, 20),
 66	ETSI_PATTERN(5,  0,  2,  300,  400, 3, 10),
 67	ETSI_PATTERN(6,  0,  2,  400, 1200, 3, 15),
 68};
 69
 70static const struct radar_types etsi_radar_types_v15 = {
 71	.region			= NL80211_DFS_ETSI,
 72	.num_radar_types	= ARRAY_SIZE(etsi_radar_ref_types_v15),
 73	.radar_types		= etsi_radar_ref_types_v15,
 74};
 75
 76/* for now, we support ETSI radar types, FCC and JP are TODO */
 77static const struct radar_types *dfs_domains[] = {
 78	&etsi_radar_types_v15,
 79};
 80
 81/**
 82 * get_dfs_domain_radar_types() - get radar types for a given DFS domain
 83 * @param domain DFS domain
 84 * @return radar_types ptr on success, NULL if DFS domain is not supported
 85 */
 86static const struct radar_types *
 87get_dfs_domain_radar_types(enum nl80211_dfs_regions region)
 88{
 89	u32 i;
 90	for (i = 0; i < ARRAY_SIZE(dfs_domains); i++) {
 91		if (dfs_domains[i]->region == region)
 92			return dfs_domains[i];
 93	}
 94	return NULL;
 95}
 96
 97/**
 98 * struct channel_detector - detector elements for a DFS channel
 99 * @head: list_head
100 * @freq: frequency for this channel detector in MHz
101 * @detectors: array of dynamically created detector elements for this freq
102 *
103 * Channel detectors are required to provide multi-channel DFS detection, e.g.
104 * to support off-channel scanning. A pattern detector has a list of channels
105 * radar pulses have been reported for in the past.
106 */
107struct channel_detector {
108	struct list_head head;
109	u16 freq;
110	struct pri_detector **detectors;
111};
112
113/* channel_detector_reset() - reset detector lines for a given channel */
114static void channel_detector_reset(struct dfs_pattern_detector *dpd,
115				   struct channel_detector *cd)
116{
117	u32 i;
118	if (cd == NULL)
119		return;
120	for (i = 0; i < dpd->num_radar_types; i++)
121		cd->detectors[i]->reset(cd->detectors[i], dpd->last_pulse_ts);
122}
123
124/* channel_detector_exit() - destructor */
125static void channel_detector_exit(struct dfs_pattern_detector *dpd,
126				  struct channel_detector *cd)
127{
128	u32 i;
129	if (cd == NULL)
130		return;
131	list_del(&cd->head);
132	for (i = 0; i < dpd->num_radar_types; i++) {
133		struct pri_detector *de = cd->detectors[i];
134		if (de != NULL)
135			de->exit(de);
136	}
137	kfree(cd->detectors);
138	kfree(cd);
139}
140
141static struct channel_detector *
142channel_detector_create(struct dfs_pattern_detector *dpd, u16 freq)
143{
144	u32 sz, i;
145	struct channel_detector *cd;
146
147	cd = kmalloc(sizeof(*cd), GFP_ATOMIC);
148	if (cd == NULL)
149		goto fail;
150
151	INIT_LIST_HEAD(&cd->head);
152	cd->freq = freq;
153	sz = sizeof(cd->detectors) * dpd->num_radar_types;
154	cd->detectors = kzalloc(sz, GFP_ATOMIC);
155	if (cd->detectors == NULL)
156		goto fail;
157
158	for (i = 0; i < dpd->num_radar_types; i++) {
159		const struct radar_detector_specs *rs = &dpd->radar_spec[i];
160		struct pri_detector *de = pri_detector_init(rs);
161		if (de == NULL)
162			goto fail;
163		cd->detectors[i] = de;
164	}
165	list_add(&cd->head, &dpd->channel_detectors);
166	return cd;
167
168fail:
169	ath_dbg(dpd->common, DFS,
170		"failed to allocate channel_detector for freq=%d\n", freq);
171	channel_detector_exit(dpd, cd);
172	return NULL;
173}
174
175/**
176 * channel_detector_get() - get channel detector for given frequency
177 * @param dpd instance pointer
178 * @param freq frequency in MHz
179 * @return pointer to channel detector on success, NULL otherwise
180 *
181 * Return existing channel detector for the given frequency or return a
182 * newly create one.
183 */
184static struct channel_detector *
185channel_detector_get(struct dfs_pattern_detector *dpd, u16 freq)
186{
187	struct channel_detector *cd;
188	list_for_each_entry(cd, &dpd->channel_detectors, head) {
189		if (cd->freq == freq)
190			return cd;
191	}
192	return channel_detector_create(dpd, freq);
193}
194
195/*
196 * DFS Pattern Detector
197 */
198
199/* dpd_reset(): reset all channel detectors */
200static void dpd_reset(struct dfs_pattern_detector *dpd)
201{
202	struct channel_detector *cd;
203	if (!list_empty(&dpd->channel_detectors))
204		list_for_each_entry(cd, &dpd->channel_detectors, head)
205			channel_detector_reset(dpd, cd);
206
207}
208static void dpd_exit(struct dfs_pattern_detector *dpd)
209{
210	struct channel_detector *cd, *cd0;
211	if (!list_empty(&dpd->channel_detectors))
212		list_for_each_entry_safe(cd, cd0, &dpd->channel_detectors, head)
213			channel_detector_exit(dpd, cd);
214	kfree(dpd);
215}
216
217static bool
218dpd_add_pulse(struct dfs_pattern_detector *dpd, struct pulse_event *event)
219{
220	u32 i;
221	struct channel_detector *cd;
222
223	/*
224	 * pulses received for a non-supported or un-initialized
225	 * domain are treated as detected radars for fail-safety
226	 */
227	if (dpd->region == NL80211_DFS_UNSET)
228		return true;
229
230	cd = channel_detector_get(dpd, event->freq);
231	if (cd == NULL)
232		return false;
233
234	dpd->last_pulse_ts = event->ts;
235	/* reset detector on time stamp wraparound, caused by TSF reset */
236	if (event->ts < dpd->last_pulse_ts)
237		dpd_reset(dpd);
238
239	/* do type individual pattern matching */
240	for (i = 0; i < dpd->num_radar_types; i++) {
241		struct pri_detector *pd = cd->detectors[i];
242		struct pri_sequence *ps = pd->add_pulse(pd, event);
243		if (ps != NULL) {
244			ath_dbg(dpd->common, DFS,
245				"DFS: radar found on freq=%d: id=%d, pri=%d, "
246				"count=%d, count_false=%d\n",
247				event->freq, pd->rs->type_id,
248				ps->pri, ps->count, ps->count_falses);
249			channel_detector_reset(dpd, cd);
250			return true;
251		}
252	}
253	return false;
254}
255
256static struct ath_dfs_pool_stats
257dpd_get_stats(struct dfs_pattern_detector *dpd)
258{
259	return global_dfs_pool_stats;
260}
261
262static bool dpd_set_domain(struct dfs_pattern_detector *dpd,
263			   enum nl80211_dfs_regions region)
264{
265	const struct radar_types *rt;
266	struct channel_detector *cd, *cd0;
267
268	if (dpd->region == region)
269		return true;
270
271	dpd->region = NL80211_DFS_UNSET;
272
273	rt = get_dfs_domain_radar_types(region);
274	if (rt == NULL)
275		return false;
276
277	/* delete all channel detectors for previous DFS domain */
278	if (!list_empty(&dpd->channel_detectors))
279		list_for_each_entry_safe(cd, cd0, &dpd->channel_detectors, head)
280			channel_detector_exit(dpd, cd);
281	dpd->radar_spec = rt->radar_types;
282	dpd->num_radar_types = rt->num_radar_types;
283
284	dpd->region = region;
285	return true;
286}
287
288static struct dfs_pattern_detector default_dpd = {
289	.exit		= dpd_exit,
290	.set_dfs_domain	= dpd_set_domain,
291	.add_pulse	= dpd_add_pulse,
292	.get_stats	= dpd_get_stats,
293	.region		= NL80211_DFS_UNSET,
294};
295
296struct dfs_pattern_detector *
297dfs_pattern_detector_init(struct ath_common *common,
298			  enum nl80211_dfs_regions region)
299{
300	struct dfs_pattern_detector *dpd;
301
302	if (!config_enabled(CONFIG_CFG80211_CERTIFICATION_ONUS))
303		return NULL;
304
305	dpd = kmalloc(sizeof(*dpd), GFP_KERNEL);
306	if (dpd == NULL)
307		return NULL;
308
309	*dpd = default_dpd;
310	INIT_LIST_HEAD(&dpd->channel_detectors);
311
312	dpd->common = common;
313	if (dpd->set_dfs_domain(dpd, region))
314		return dpd;
315
316	ath_dbg(common, DFS,"Could not set DFS domain to %d", region);
317	kfree(dpd);
318	return NULL;
319}
320EXPORT_SYMBOL(dfs_pattern_detector_init);