dfs_pattern_detector.c

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/*
 * 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/export.h>

#include "dfs_pattern_detector.h"
#include "dfs_pri_detector.h"

/*
 * tolerated deviation of radar time stamp in usecs on both sides
 * TODO: this might need to be HW-dependent
 */
#define PRI_TOLERANCE   16

struct radar_types {
    enum nl80211_dfs_regions region;
    u32 num_radar_types;
    const struct radar_detector_specs *radar_types;
};

/* percentage on ppb threshold to trigger detection */
#define MIN_PPB_THRESH  50
#define PPB_THRESH(PPB) ((PPB * MIN_PPB_THRESH + 50) / 100)
#define PRF2PRI(PRF) ((1000000 + PRF / 2) / PRF)

#define ETSI_PATTERN(ID, WMIN, WMAX, PMIN, PMAX, PRF, PPB)  \
{                               \
    ID, WMIN, WMAX, (PRF2PRI(PMAX) - PRI_TOLERANCE),    \
    (PRF2PRI(PMIN) * PRF + PRI_TOLERANCE), PRF, PPB * PRF,  \
    PPB_THRESH(PPB), PRI_TOLERANCE,             \
}

/* radar types as defined by ETSI EN-301-893 v1.5.1 */
static const struct radar_detector_specs etsi_radar_ref_types_v15[] = {
    ETSI_PATTERN(0,  0,  1,  700,  700, 1, 18),
    ETSI_PATTERN(1,  0,  5,  200, 1000, 1, 10),
    ETSI_PATTERN(2,  0, 15,  200, 1600, 1, 15),
    ETSI_PATTERN(3,  0, 15, 2300, 4000, 1, 25),
    ETSI_PATTERN(4, 20, 30, 2000, 4000, 1, 20),
    ETSI_PATTERN(5,  0,  2,  300,  400, 3, 10),
    ETSI_PATTERN(6,  0,  2,  400, 1200, 3, 15),
};

static const struct radar_types etsi_radar_types_v15 = {
    .region         = NL80211_DFS_ETSI,
    .num_radar_types    = ARRAY_SIZE(etsi_radar_ref_types_v15),
    .radar_types        = etsi_radar_ref_types_v15,
};

/* for now, we support ETSI radar types, FCC and JP are TODO */
static const struct radar_types *dfs_domains[] = {
    &etsi_radar_types_v15,
};

static const struct radar_types *
get_dfs_domain_radar_types(enum nl80211_dfs_regions region)
{
    u32 i;
    for (i = 0; i < ARRAY_SIZE(dfs_domains); i++) {
        if (dfs_domains[i]->region == region)
            return dfs_domains[i];
    }
    return NULL;
}

struct channel_detector {
    struct list_head head;
    u16 freq;
    struct pri_detector **detectors;
};

/* channel_detector_reset() - reset detector lines for a given channel */
static void channel_detector_reset(struct dfs_pattern_detector *dpd,
                   struct channel_detector *cd)
{
    u32 i;
    if (cd == NULL)
        return;
    for (i = 0; i < dpd->num_radar_types; i++)
        cd->detectors[i]->reset(cd->detectors[i], dpd->last_pulse_ts);
}

/* channel_detector_exit() - destructor */
static void channel_detector_exit(struct dfs_pattern_detector *dpd,
                  struct channel_detector *cd)
{
    u32 i;
    if (cd == NULL)
        return;
    list_del(&cd->head);
    for (i = 0; i < dpd->num_radar_types; i++) {
        struct pri_detector *de = cd->detectors[i];
        if (de != NULL)
            de->exit(de);
    }
    kfree(cd->detectors);
    kfree(cd);
}

static struct channel_detector *
channel_detector_create(struct dfs_pattern_detector *dpd, u16 freq)
{
    u32 sz, i;
    struct channel_detector *cd;

    cd = kmalloc(sizeof(*cd), GFP_KERNEL);
    if (cd == NULL)
        goto fail;

    INIT_LIST_HEAD(&cd->head);
    cd->freq = freq;
    sz = sizeof(cd->detectors) * dpd->num_radar_types;
    cd->detectors = kzalloc(sz, GFP_KERNEL);
    if (cd->detectors == NULL)
        goto fail;

    for (i = 0; i < dpd->num_radar_types; i++) {
        const struct radar_detector_specs *rs = &dpd->radar_spec[i];
        struct pri_detector *de = pri_detector_init(rs);
        if (de == NULL)
            goto fail;
        cd->detectors[i] = de;
    }
    list_add(&cd->head, &dpd->channel_detectors);
    return cd;

fail:
    pr_err("failed to allocate channel_detector for freq=%d\n", freq);
    channel_detector_exit(dpd, cd);
    return NULL;
}

static struct channel_detector *
channel_detector_get(struct dfs_pattern_detector *dpd, u16 freq)
{
    struct channel_detector *cd;
    list_for_each_entry(cd, &dpd->channel_detectors, head) {
        if (cd->freq == freq)
            return cd;
    }
    return channel_detector_create(dpd, freq);
}

/*
 * DFS Pattern Detector
 */

/* dpd_reset(): reset all channel detectors */
static void dpd_reset(struct dfs_pattern_detector *dpd)
{
    struct channel_detector *cd;
    if (!list_empty(&dpd->channel_detectors))
        list_for_each_entry(cd, &dpd->channel_detectors, head)
            channel_detector_reset(dpd, cd);

}
static void dpd_exit(struct dfs_pattern_detector *dpd)
{
    struct channel_detector *cd, *cd0;
    if (!list_empty(&dpd->channel_detectors))
        list_for_each_entry_safe(cd, cd0, &dpd->channel_detectors, head)
            channel_detector_exit(dpd, cd);
    kfree(dpd);
}

static bool
dpd_add_pulse(struct dfs_pattern_detector *dpd, struct pulse_event *event)
{
    u32 i;
    bool ts_wraparound;
    struct channel_detector *cd;

    if (dpd->region == NL80211_DFS_UNSET) {
        /*
         * pulses received for a non-supported or un-initialized
         * domain are treated as detected radars
         */
        return true;
    }

    cd = channel_detector_get(dpd, event->freq);
    if (cd == NULL)
        return false;

    ts_wraparound = (event->ts < dpd->last_pulse_ts);
    dpd->last_pulse_ts = event->ts;
    if (ts_wraparound) {
        /*
         * reset detector on time stamp wraparound
         * with monotonic time stamps, this should never happen
         */
        pr_warn("DFS: time stamp wraparound detected, resetting\n");
        dpd_reset(dpd);
    }
    /* do type individual pattern matching */
    for (i = 0; i < dpd->num_radar_types; i++) {
        if (cd->detectors[i]->add_pulse(cd->detectors[i], event) != 0) {
            channel_detector_reset(dpd, cd);
            return true;
        }
    }
    return false;
}

static bool dpd_set_domain(struct dfs_pattern_detector *dpd,
               enum nl80211_dfs_regions region)
{
    const struct radar_types *rt;
    struct channel_detector *cd, *cd0;

    if (dpd->region == region)
        return true;

    dpd->region = NL80211_DFS_UNSET;

    rt = get_dfs_domain_radar_types(region);
    if (rt == NULL)
        return false;

    /* delete all channel detectors for previous DFS domain */
    if (!list_empty(&dpd->channel_detectors))
        list_for_each_entry_safe(cd, cd0, &dpd->channel_detectors, head)
            channel_detector_exit(dpd, cd);
    dpd->radar_spec = rt->radar_types;
    dpd->num_radar_types = rt->num_radar_types;

    dpd->region = region;
    return true;
}

static struct dfs_pattern_detector default_dpd = {
    .exit       = dpd_exit,
    .set_domain = dpd_set_domain,
    .add_pulse  = dpd_add_pulse,
    .region     = NL80211_DFS_UNSET,
};

struct dfs_pattern_detector *
dfs_pattern_detector_init(enum nl80211_dfs_regions region)
{
    struct dfs_pattern_detector *dpd;
    dpd = kmalloc(sizeof(*dpd), GFP_KERNEL);
    if (dpd == NULL) {
        pr_err("allocation of dfs_pattern_detector failed\n");
        return NULL;
    }
    *dpd = default_dpd;
    INIT_LIST_HEAD(&dpd->channel_detectors);

    if (dpd->set_domain(dpd, region))
        return dpd;

    pr_err("Could not set DFS domain to %d. ", region);
    return NULL;
}
EXPORT_SYMBOL(dfs_pattern_detector_init);