/*
 * Ultra Wide Band
 * Beacon management
 *
 * Copyright (C) 2005-2006 Intel Corporation
 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
 *
 * 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;

        dev_dbg(dev, "%s: channel = %d\n", __func__, channel);
        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) {
                        dev_err(dev, "Cannot start beaconing: %d\n", result);
                        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;
}

/**
 * uwb_dev_get_by_devaddr - get a UWB device with a specific DevAddr
 * @rc:      the radio controller that saw the device
 * @devaddr: DevAddr of the UWB device to find
 *
 * There may be more than one matching device (in the case of a
 * DevAddr conflict), but only the first one is returned.
 */
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;
}

/**
 * uwb_dev_get_by_macaddr - get a UWB device with a specific EUI-48
 * @rc:      the radio controller that saw the device
 * @devaddr: EUI-48 of the UWB device to find
 */
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;

        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);

        /* 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;
}

/**
 * uwbd_evt_handle_rc_bp_slot_change - handle a BP_SLOT_CHANGE event
 * @evt: the BP_SLOT_CHANGE notification from the radio controller
 *
 * If the event indicates that no beacon period slots were available
 * then radio controller has transitioned to a non-beaconing state.
 * Otherwise, simply save the current beacon slot.
 */
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);

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

        return 0;
}

/**
 * Handle UWB_RC_EVT_BPOIE_CHANGE events
 *
 * XXXXX
 */
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);