beacon.c

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/*
 * Ultra Wide Band
 * Beacon management
 *
 * Copyright (C) 2005-2006 Intel Corporation
 * Inaky Perez-Gonzalez <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 *
 * FIXME: docs
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/kdev_t.h>
#include <linux/slab.h>

#include "uwb-internal.h"

/* Start Beaconing command structure */
struct uwb_rc_cmd_start_beacon {
    struct uwb_rccb rccb;
    __le16 wBPSTOffset;
    u8 bChannelNumber;
} __attribute__((packed));


static int uwb_rc_start_beacon(struct uwb_rc *rc, u16 bpst_offset, u8 channel)
{
    int result;
    struct uwb_rc_cmd_start_beacon *cmd;
    struct uwb_rc_evt_confirm reply;

    cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
    if (cmd == NULL)
        return -ENOMEM;
    cmd->rccb.bCommandType = UWB_RC_CET_GENERAL;
    cmd->rccb.wCommand = cpu_to_le16(UWB_RC_CMD_START_BEACON);
    cmd->wBPSTOffset = cpu_to_le16(bpst_offset);
    cmd->bChannelNumber = channel;
    reply.rceb.bEventType = UWB_RC_CET_GENERAL;
    reply.rceb.wEvent = UWB_RC_CMD_START_BEACON;
    result = uwb_rc_cmd(rc, "START-BEACON", &cmd->rccb, sizeof(*cmd),
                &reply.rceb, sizeof(reply));
    if (result < 0)
        goto error_cmd;
    if (reply.bResultCode != UWB_RC_RES_SUCCESS) {
        dev_err(&rc->uwb_dev.dev,
            "START-BEACON: command execution failed: %s (%d)\n",
            uwb_rc_strerror(reply.bResultCode), reply.bResultCode);
        result = -EIO;
    }
error_cmd:
    kfree(cmd);
    return result;
}

static int uwb_rc_stop_beacon(struct uwb_rc *rc)
{
    int result;
    struct uwb_rccb *cmd;
    struct uwb_rc_evt_confirm reply;

    cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
    if (cmd == NULL)
        return -ENOMEM;
    cmd->bCommandType = UWB_RC_CET_GENERAL;
    cmd->wCommand = cpu_to_le16(UWB_RC_CMD_STOP_BEACON);
    reply.rceb.bEventType = UWB_RC_CET_GENERAL;
    reply.rceb.wEvent = UWB_RC_CMD_STOP_BEACON;
    result = uwb_rc_cmd(rc, "STOP-BEACON", cmd, sizeof(*cmd),
                &reply.rceb, sizeof(reply));
    if (result < 0)
        goto error_cmd;
    if (reply.bResultCode != UWB_RC_RES_SUCCESS) {
        dev_err(&rc->uwb_dev.dev,
            "STOP-BEACON: command execution failed: %s (%d)\n",
            uwb_rc_strerror(reply.bResultCode), reply.bResultCode);
        result = -EIO;
    }
error_cmd:
    kfree(cmd);
    return result;
}

/*
 * Start/stop beacons
 *
 * @rc:          UWB Radio Controller to operate on
 * @channel:     UWB channel on which to beacon (WUSB[table
 *               5-12]). If -1, stop beaconing.
 * @bpst_offset: Beacon Period Start Time offset; FIXME-do zero
 *
 * According to WHCI 0.95 [4.13.6] the driver will only receive the RCEB
 * of a SET IE command after the device sent the first beacon that includes
 * the IEs specified in the SET IE command. So, after we start beaconing we
 * check if there is anything in the IE cache and call the SET IE command
 * if needed.
 */
int uwb_rc_beacon(struct uwb_rc *rc, int channel, unsigned bpst_offset)
{
    int result;
    struct device *dev = &rc->uwb_dev.dev;

    if (channel < 0)
        channel = -1;
    if (channel == -1)
        result = uwb_rc_stop_beacon(rc);
    else {
        /* channel >= 0...dah */
        result = uwb_rc_start_beacon(rc, bpst_offset, channel);
        if (result < 0)
            return result;
        if (le16_to_cpu(rc->ies->wIELength) > 0) {
            result = uwb_rc_set_ie(rc, rc->ies);
            if (result < 0) {
                dev_err(dev, "Cannot set new IE on device: "
                    "%d\n", result);
                result = uwb_rc_stop_beacon(rc);
                channel = -1;
                bpst_offset = 0;
            }
        }
    }

    if (result >= 0)
        rc->beaconing = channel;
    return result;
}

/*
 * Beacon cache
 *
 * The purpose of this is to speed up the lookup of becon information
 * when a new beacon arrives. The UWB Daemon uses it also to keep a
 * tab of which devices are in radio distance and which not. When a
 * device's beacon stays present for more than a certain amount of
 * time, it is considered a new, usable device. When a beacon ceases
 * to be received for a certain amount of time, it is considered that
 * the device is gone.
 *
 * FIXME: use an allocator for the entries
 * FIXME: use something faster for search than a list
 */

void uwb_bce_kfree(struct kref *_bce)
{
    struct uwb_beca_e *bce = container_of(_bce, struct uwb_beca_e, refcnt);

    kfree(bce->be);
    kfree(bce);
}


/* Find a beacon by dev addr in the cache */
static
struct uwb_beca_e *__uwb_beca_find_bydev(struct uwb_rc *rc,
                     const struct uwb_dev_addr *dev_addr)
{
    struct uwb_beca_e *bce, *next;
    list_for_each_entry_safe(bce, next, &rc->uwb_beca.list, node) {
        if (!memcmp(&bce->dev_addr, dev_addr, sizeof(bce->dev_addr)))
            goto out;
    }
    bce = NULL;
out:
    return bce;
}

/* Find a beacon by dev addr in the cache */
static
struct uwb_beca_e *__uwb_beca_find_bymac(struct uwb_rc *rc, 
                     const struct uwb_mac_addr *mac_addr)
{
    struct uwb_beca_e *bce, *next;
    list_for_each_entry_safe(bce, next, &rc->uwb_beca.list, node) {
        if (!memcmp(bce->mac_addr, mac_addr->data,
                sizeof(struct uwb_mac_addr)))
            goto out;
    }
    bce = NULL;
out:
    return bce;
}

struct uwb_dev *uwb_dev_get_by_devaddr(struct uwb_rc *rc,
                       const struct uwb_dev_addr *devaddr)
{
    struct uwb_dev *found = NULL;
    struct uwb_beca_e *bce;

    mutex_lock(&rc->uwb_beca.mutex);
    bce = __uwb_beca_find_bydev(rc, devaddr);
    if (bce)
        found = uwb_dev_try_get(rc, bce->uwb_dev);
    mutex_unlock(&rc->uwb_beca.mutex);

    return found;
}

struct uwb_dev *uwb_dev_get_by_macaddr(struct uwb_rc *rc,
                       const struct uwb_mac_addr *macaddr)
{
    struct uwb_dev *found = NULL;
    struct uwb_beca_e *bce;

    mutex_lock(&rc->uwb_beca.mutex);
    bce = __uwb_beca_find_bymac(rc, macaddr);
    if (bce)
        found = uwb_dev_try_get(rc, bce->uwb_dev);
    mutex_unlock(&rc->uwb_beca.mutex);

    return found;
}

/* Initialize a beacon cache entry */
static void uwb_beca_e_init(struct uwb_beca_e *bce)
{
    mutex_init(&bce->mutex);
    kref_init(&bce->refcnt);
    stats_init(&bce->lqe_stats);
    stats_init(&bce->rssi_stats);
}

/*
 * Add a beacon to the cache
 *
 * @be:         Beacon event information
 * @bf:         Beacon frame (part of b, really)
 * @ts_jiffies: Timestamp (in jiffies) when the beacon was received
 */
static
struct uwb_beca_e *__uwb_beca_add(struct uwb_rc *rc,
                  struct uwb_rc_evt_beacon *be,
                  struct uwb_beacon_frame *bf,
                  unsigned long ts_jiffies)
{
    struct uwb_beca_e *bce;

    bce = kzalloc(sizeof(*bce), GFP_KERNEL);
    if (bce == NULL)
        return NULL;
    uwb_beca_e_init(bce);
    bce->ts_jiffies = ts_jiffies;
    bce->uwb_dev = NULL;
    list_add(&bce->node, &rc->uwb_beca.list);
    return bce;
}

/*
 * Wipe out beacon entries that became stale
 *
 * Remove associated devicest too.
 */
void uwb_beca_purge(struct uwb_rc *rc)
{
    struct uwb_beca_e *bce, *next;
    unsigned long expires;

    mutex_lock(&rc->uwb_beca.mutex);
    list_for_each_entry_safe(bce, next, &rc->uwb_beca.list, node) {
        expires = bce->ts_jiffies + msecs_to_jiffies(beacon_timeout_ms);
        if (time_after(jiffies, expires)) {
            uwbd_dev_offair(bce);
        }
    }
    mutex_unlock(&rc->uwb_beca.mutex);
}

/* Clean up the whole beacon cache. Called on shutdown */
void uwb_beca_release(struct uwb_rc *rc)
{
    struct uwb_beca_e *bce, *next;

    mutex_lock(&rc->uwb_beca.mutex);
    list_for_each_entry_safe(bce, next, &rc->uwb_beca.list, node) {
        list_del(&bce->node);
        uwb_bce_put(bce);
    }
    mutex_unlock(&rc->uwb_beca.mutex);
}

static void uwb_beacon_print(struct uwb_rc *rc, struct uwb_rc_evt_beacon *be,
                 struct uwb_beacon_frame *bf)
{
    char macbuf[UWB_ADDR_STRSIZE];
    char devbuf[UWB_ADDR_STRSIZE];
    char dstbuf[UWB_ADDR_STRSIZE];

    uwb_mac_addr_print(macbuf, sizeof(macbuf), &bf->Device_Identifier);
    uwb_dev_addr_print(devbuf, sizeof(devbuf), &bf->hdr.SrcAddr);
    uwb_dev_addr_print(dstbuf, sizeof(dstbuf), &bf->hdr.DestAddr);
    dev_info(&rc->uwb_dev.dev,
         "BEACON from %s to %s (ch%u offset %u slot %u MAC %s)\n",
         devbuf, dstbuf, be->bChannelNumber, be->wBPSTOffset,
         bf->Beacon_Slot_Number, macbuf);
}

/*
 * @bce: beacon cache entry, referenced
 */
ssize_t uwb_bce_print_IEs(struct uwb_dev *uwb_dev, struct uwb_beca_e *bce,
              char *buf, size_t size)
{
    ssize_t result = 0;
    struct uwb_rc_evt_beacon *be;
    struct uwb_beacon_frame *bf;
    int ies_len;
    struct uwb_ie_hdr *ies;

    mutex_lock(&bce->mutex);

    be = bce->be;
    if (be) {
        bf = (struct uwb_beacon_frame *)bce->be->BeaconInfo;
        ies_len = be->wBeaconInfoLength - sizeof(struct uwb_beacon_frame);
        ies = (struct uwb_ie_hdr *)bf->IEData;

        result = uwb_ie_dump_hex(ies, ies_len, buf, size);
    }

    mutex_unlock(&bce->mutex);

    return result;
}

/*
 * Verify that the beacon event, frame and IEs are ok
 */
static int uwb_verify_beacon(struct uwb_rc *rc, struct uwb_event *evt,
                 struct uwb_rc_evt_beacon *be)
{
    int result = -EINVAL;
    struct uwb_beacon_frame *bf;
    struct device *dev = &rc->uwb_dev.dev;

    /* Is there enough data to decode a beacon frame? */
    if (evt->notif.size < sizeof(*be) + sizeof(*bf)) {
        dev_err(dev, "BEACON event: Not enough data to decode "
            "(%zu vs %zu bytes needed)\n", evt->notif.size,
            sizeof(*be) + sizeof(*bf));
        goto error;
    }
    /* FIXME: make sure beacon frame IEs are fine and that the whole thing
     * is consistent */
    result = 0;
error:
    return result;
}

/*
 * Handle UWB_RC_EVT_BEACON events
 *
 * We check the beacon cache to see how the received beacon fares. If
 * is there already we refresh the timestamp. If not we create a new
 * entry.
 *
 * According to the WHCI and WUSB specs, only one beacon frame is
 * allowed per notification block, so we don't bother about scanning
 * for more.
 */
int uwbd_evt_handle_rc_beacon(struct uwb_event *evt)
{
    int result = -EINVAL;
    struct uwb_rc *rc;
    struct uwb_rc_evt_beacon *be;
    struct uwb_beacon_frame *bf;
    struct uwb_beca_e *bce;
    unsigned long last_ts;

    rc = evt->rc;
    be = container_of(evt->notif.rceb, struct uwb_rc_evt_beacon, rceb);
    result = uwb_verify_beacon(rc, evt, be);
    if (result < 0)
        return result;

    /* FIXME: handle alien beacons. */
    if (be->bBeaconType == UWB_RC_BEACON_TYPE_OL_ALIEN ||
        be->bBeaconType == UWB_RC_BEACON_TYPE_NOL_ALIEN) {
        return -ENOSYS;
    }

    bf = (struct uwb_beacon_frame *) be->BeaconInfo;

    /*
     * Drop beacons from devices with a NULL EUI-48 -- they cannot
     * be uniquely identified.
     *
     * It's expected that these will all be WUSB devices and they
     * have a WUSB specific connection method so ignoring them
     * here shouldn't be a problem.
     */
    if (uwb_mac_addr_bcast(&bf->Device_Identifier))
        return 0;

    mutex_lock(&rc->uwb_beca.mutex);
    bce = __uwb_beca_find_bymac(rc, &bf->Device_Identifier);
    if (bce == NULL) {
        /* Not in there, a new device is pinging */
        uwb_beacon_print(evt->rc, be, bf);
        bce = __uwb_beca_add(rc, be, bf, evt->ts_jiffies);
        if (bce == NULL) {
            mutex_unlock(&rc->uwb_beca.mutex);
            return -ENOMEM;
        }
    }
    mutex_unlock(&rc->uwb_beca.mutex);

    mutex_lock(&bce->mutex);
    /* purge old beacon data */
    kfree(bce->be);

    last_ts = bce->ts_jiffies;

    /* Update commonly used fields */
    bce->ts_jiffies = evt->ts_jiffies;
    bce->be = be;
    bce->dev_addr = bf->hdr.SrcAddr;
    bce->mac_addr = &bf->Device_Identifier;
    be->wBPSTOffset = le16_to_cpu(be->wBPSTOffset);
    be->wBeaconInfoLength = le16_to_cpu(be->wBeaconInfoLength);
    stats_add_sample(&bce->lqe_stats, be->bLQI - 7);
    stats_add_sample(&bce->rssi_stats, be->bRSSI + 18);

    /*
     * This might be a beacon from a new device.
     */
    if (bce->uwb_dev == NULL)
        uwbd_dev_onair(evt->rc, bce);

    mutex_unlock(&bce->mutex);

    return 1; /* we keep the event data */
}

/*
 * Handle UWB_RC_EVT_BEACON_SIZE events
 *
 * XXXXX
 */
int uwbd_evt_handle_rc_beacon_size(struct uwb_event *evt)
{
    int result = -EINVAL;
    struct device *dev = &evt->rc->uwb_dev.dev;
    struct uwb_rc_evt_beacon_size *bs;

    /* Is there enough data to decode the event? */
    if (evt->notif.size < sizeof(*bs)) {
        dev_err(dev, "BEACON SIZE notification: Not enough data to "
            "decode (%zu vs %zu bytes needed)\n",
            evt->notif.size, sizeof(*bs));
        goto error;
    }
    bs = container_of(evt->notif.rceb, struct uwb_rc_evt_beacon_size, rceb);
    if (0)
        dev_info(dev, "Beacon size changed to %u bytes "
            "(FIXME: action?)\n", le16_to_cpu(bs->wNewBeaconSize));
    else {
        /* temporary hack until we do something with this message... */
        static unsigned count;
        if (++count % 1000 == 0)
            dev_info(dev, "Beacon size changed %u times "
                "(FIXME: action?)\n", count);
    }
    result = 0;
error:
    return result;
}

int uwbd_evt_handle_rc_bp_slot_change(struct uwb_event *evt)
{
    struct uwb_rc *rc = evt->rc;
    struct device *dev = &rc->uwb_dev.dev;
    struct uwb_rc_evt_bp_slot_change *bpsc;

    if (evt->notif.size < sizeof(*bpsc)) {
        dev_err(dev, "BP SLOT CHANGE event: Not enough data\n");
        return -EINVAL;
    }
    bpsc = container_of(evt->notif.rceb, struct uwb_rc_evt_bp_slot_change, rceb);

    mutex_lock(&rc->uwb_dev.mutex);
    if (uwb_rc_evt_bp_slot_change_no_slot(bpsc)) {
        dev_info(dev, "stopped beaconing: No free slots in BP\n");
        rc->beaconing = -1;
    } else
        rc->uwb_dev.beacon_slot = uwb_rc_evt_bp_slot_change_slot_num(bpsc);
    mutex_unlock(&rc->uwb_dev.mutex);

    return 0;
}

struct uwb_ie_bpo {
    struct uwb_ie_hdr hdr;
    u8                bp_length;
    u8                data[];
} __attribute__((packed));

int uwbd_evt_handle_rc_bpoie_change(struct uwb_event *evt)
{
    int result = -EINVAL;
    struct device *dev = &evt->rc->uwb_dev.dev;
    struct uwb_rc_evt_bpoie_change *bpoiec;
    struct uwb_ie_bpo *bpoie;
    static unsigned count;  /* FIXME: this is a temp hack */
    size_t iesize;

    /* Is there enough data to decode it? */
    if (evt->notif.size < sizeof(*bpoiec)) {
        dev_err(dev, "BPOIEC notification: Not enough data to "
            "decode (%zu vs %zu bytes needed)\n",
            evt->notif.size, sizeof(*bpoiec));
        goto error;
    }
    bpoiec = container_of(evt->notif.rceb, struct uwb_rc_evt_bpoie_change, rceb);
    iesize = le16_to_cpu(bpoiec->wBPOIELength);
    if (iesize < sizeof(*bpoie)) {
        dev_err(dev, "BPOIEC notification: Not enough IE data to "
            "decode (%zu vs %zu bytes needed)\n",
            iesize, sizeof(*bpoie));
        goto error;
    }
    if (++count % 1000 == 0)    /* Lame placeholder */
        dev_info(dev, "BPOIE: %u changes received\n", count);
    /*
     * FIXME: At this point we should go over all the IEs in the
     *        bpoiec->BPOIE array and act on each.
     */
    result = 0;
error:
    return result;
}

/*
 * Print beaconing state.
 */
static ssize_t uwb_rc_beacon_show(struct device *dev,
                  struct device_attribute *attr, char *buf)
{
    struct uwb_dev *uwb_dev = to_uwb_dev(dev);
    struct uwb_rc *rc = uwb_dev->rc;
    ssize_t result;

    mutex_lock(&rc->uwb_dev.mutex);
    result = sprintf(buf, "%d\n", rc->beaconing);
    mutex_unlock(&rc->uwb_dev.mutex);
    return result;
}

/*
 * Start beaconing on the specified channel, or stop beaconing.
 */
static ssize_t uwb_rc_beacon_store(struct device *dev,
                   struct device_attribute *attr,
                   const char *buf, size_t size)
{
    struct uwb_dev *uwb_dev = to_uwb_dev(dev);
    struct uwb_rc *rc = uwb_dev->rc;
    int channel;
    ssize_t result = -EINVAL;

    result = sscanf(buf, "%d", &channel);
    if (result >= 1)
        result = uwb_radio_force_channel(rc, channel);

    return result < 0 ? result : size;
}
DEVICE_ATTR(beacon, S_IRUGO | S_IWUSR, uwb_rc_beacon_show, uwb_rc_beacon_store);