/*
 * WiMedia Logical Link Control Protocol (WLP)
 *
 * Copyright (C) 2005-2006 Intel Corporation
 * Reinette Chatre <reinette.chatre@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/wlp.h>

#include "wlp-internal.h"

static
void wlp_neighbor_init(struct wlp_neighbor_e *neighbor)
{
        INIT_LIST_HEAD(&neighbor->wssid);
}

/**
 * Create area for device information storage
 *
 * wlp->mutex must be held
 */
int __wlp_alloc_device_info(struct wlp *wlp)
{
        struct device *dev = &wlp->rc->uwb_dev.dev;
        BUG_ON(wlp->dev_info != NULL);
        wlp->dev_info = kzalloc(sizeof(struct wlp_device_info), GFP_KERNEL);
        if (wlp->dev_info == NULL) {
                dev_err(dev, "WLP: Unable to allocate memory for "
                        "device information.\n");
                return -ENOMEM;
        }
        return 0;
}


/**
 * Fill in device information using function provided by driver
 *
 * wlp->mutex must be held
 */
static
void __wlp_fill_device_info(struct wlp *wlp)
{
        wlp->fill_device_info(wlp, wlp->dev_info);
}

/**
 * Setup device information
 *
 * Allocate area for device information and populate it.
 *
 * wlp->mutex must be held
 */
int __wlp_setup_device_info(struct wlp *wlp)
{
        int result;
        struct device *dev = &wlp->rc->uwb_dev.dev;

        result = __wlp_alloc_device_info(wlp);
        if (result < 0) {
                dev_err(dev, "WLP: Unable to allocate area for "
                        "device information.\n");
                return result;
        }
        __wlp_fill_device_info(wlp);
        return 0;
}

/**
 * Remove information about neighbor stored temporarily
 *
 * Information learned during discovey should only be stored when the
 * device enrolls in the neighbor's WSS. We do need to store this
 * information temporarily in order to present it to the user.
 *
 * We are only interested in keeping neighbor WSS information if that
 * neighbor is accepting enrollment.
 *
 * should be called with wlp->nbmutex held
 */
void wlp_remove_neighbor_tmp_info(struct wlp_neighbor_e *neighbor)
{
        struct wlp_wssid_e *wssid_e, *next;
        u8 keep;
        if (!list_empty(&neighbor->wssid)) {
                list_for_each_entry_safe(wssid_e, next, &neighbor->wssid,
                                         node) {
                        if (wssid_e->info != NULL) {
                                keep = wssid_e->info->accept_enroll;
                                kfree(wssid_e->info);
                                wssid_e->info = NULL;
                                if (!keep) {
                                        list_del(&wssid_e->node);
                                        kfree(wssid_e);
                                }
                        }
                }
        }
        if (neighbor->info != NULL) {
                kfree(neighbor->info);
                neighbor->info = NULL;
        }
}

/*
 * Populate WLP neighborhood cache with neighbor information
 *
 * A new neighbor is found. If it is discoverable then we add it to the
 * neighborhood cache.
 *
 */
static
int wlp_add_neighbor(struct wlp *wlp, struct uwb_dev *dev)
{
        int result = 0;
        int discoverable;
        struct wlp_neighbor_e *neighbor;

        /*
         * FIXME:
         * Use contents of WLP IE found in beacon cache to determine if
         * neighbor is discoverable.
         * The device does not support WLP IE yet so this still needs to be
         * done. Until then we assume all devices are discoverable.
         */
        discoverable = 1; /* will be changed when FIXME disappears */
        if (discoverable) {
                /* Add neighbor to cache for discovery */
                neighbor = kzalloc(sizeof(*neighbor), GFP_KERNEL);
                if (neighbor == NULL) {
                        dev_err(&dev->dev, "Unable to create memory for "
                                "new neighbor. \n");
                        result = -ENOMEM;
                        goto error_no_mem;
                }
                wlp_neighbor_init(neighbor);
                uwb_dev_get(dev);
                neighbor->uwb_dev = dev;
                list_add(&neighbor->node, &wlp->neighbors);
        }
error_no_mem:
        return result;
}

/**
 * Remove one neighbor from cache
 */
static
void __wlp_neighbor_release(struct wlp_neighbor_e *neighbor)
{
        struct wlp_wssid_e *wssid_e, *next_wssid_e;

        list_for_each_entry_safe(wssid_e, next_wssid_e,
                                 &neighbor->wssid, node) {
                list_del(&wssid_e->node);
                kfree(wssid_e);
        }
        uwb_dev_put(neighbor->uwb_dev);
        list_del(&neighbor->node);
        kfree(neighbor);
}

/**
 * Clear entire neighborhood cache.
 */
static
void __wlp_neighbors_release(struct wlp *wlp)
{
        struct wlp_neighbor_e *neighbor, *next;
        if (list_empty(&wlp->neighbors))
                return;
        list_for_each_entry_safe(neighbor, next, &wlp->neighbors, node) {
                __wlp_neighbor_release(neighbor);
        }
}

static
void wlp_neighbors_release(struct wlp *wlp)
{
        mutex_lock(&wlp->nbmutex);
        __wlp_neighbors_release(wlp);
        mutex_unlock(&wlp->nbmutex);
}



/**
 * Send D1 message to neighbor, receive D2 message
 *
 * @neighbor: neighbor to which D1 message will be sent
 * @wss:      if not NULL, it is an enrollment request for this WSS
 * @wssid:    if wss not NULL, this is the wssid of the WSS in which we
 *            want to enroll
 *
 * A D1/D2 exchange is done for one of two reasons: discovery or
 * enrollment. If done for discovery the D1 message is sent to the neighbor
 * and the contents of the D2 response is stored in a temporary cache.
 * If done for enrollment the @wss and @wssid are provided also. In this
 * case the D1 message is sent to the neighbor, the D2 response is parsed
 * for enrollment of the WSS with wssid.
 *
 * &wss->mutex is held
 */
static
int wlp_d1d2_exchange(struct wlp *wlp, struct wlp_neighbor_e *neighbor,
                      struct wlp_wss *wss, struct wlp_uuid *wssid)
{
        int result;
        struct device *dev = &wlp->rc->uwb_dev.dev;
        DECLARE_COMPLETION_ONSTACK(completion);
        struct wlp_session session;
        struct sk_buff  *skb;
        struct wlp_frame_assoc *resp;
        struct uwb_dev_addr *dev_addr = &neighbor->uwb_dev->dev_addr;

        mutex_lock(&wlp->mutex);
        if (!wlp_uuid_is_set(&wlp->uuid)) {
                dev_err(dev, "WLP: UUID is not set. Set via sysfs to "
                        "proceed.\n");
                result = -ENXIO;
                goto out;
        }
        /* Send D1 association frame */
        result = wlp_send_assoc_frame(wlp, wss, dev_addr, WLP_ASSOC_D1);
        if (result < 0) {
                dev_err(dev, "Unable to send D1 frame to neighbor "
                        "%02x:%02x (%d)\n", dev_addr->data[1],
                        dev_addr->data[0], result);
                goto out;
        }
        /* Create session, wait for response */
        session.exp_message = WLP_ASSOC_D2;
        session.cb = wlp_session_cb;
        session.cb_priv = &completion;
        session.neighbor_addr = *dev_addr;
        BUG_ON(wlp->session != NULL);
        wlp->session = &session;
        /* Wait for D2/F0 frame */
        result = wait_for_completion_interruptible_timeout(&completion,
                                                   WLP_PER_MSG_TIMEOUT * HZ);
        if (result == 0) {
                result = -ETIMEDOUT;
                dev_err(dev, "Timeout while sending D1 to neighbor "
                             "%02x:%02x.\n", dev_addr->data[1],
                             dev_addr->data[0]);
                goto error_session;
        }
        if (result < 0) {
                dev_err(dev, "Unable to discover/enroll neighbor %02x:%02x.\n",
                        dev_addr->data[1], dev_addr->data[0]);
                goto error_session;
        }
        /* Parse message in session->data: it will be either D2 or F0 */
        skb = session.data;
        resp = (void *) skb->data;

        if (resp->type == WLP_ASSOC_F0) {
                result = wlp_parse_f0(wlp, skb);
                if (result < 0)
                        dev_err(dev, "WLP: Unable to parse F0 from neighbor "
                                "%02x:%02x.\n", dev_addr->data[1],
                                dev_addr->data[0]);
                result = -EINVAL;
                goto error_resp_parse;
        }
        if (wss == NULL) {
                /* Discovery */
                result = wlp_parse_d2_frame_to_cache(wlp, skb, neighbor);
                if (result < 0) {
                        dev_err(dev, "WLP: Unable to parse D2 message from "
                                "neighbor %02x:%02x for discovery.\n",
                                dev_addr->data[1], dev_addr->data[0]);
                        goto error_resp_parse;
                }
        } else {
                /* Enrollment */
                result = wlp_parse_d2_frame_to_enroll(wss, skb, neighbor,
                                                      wssid);
                if (result < 0) {
                        dev_err(dev, "WLP: Unable to parse D2 message from "
                                "neighbor %02x:%02x for enrollment.\n",
                                dev_addr->data[1], dev_addr->data[0]);
                        goto error_resp_parse;
                }
        }
error_resp_parse:
        kfree_skb(skb);
error_session:
        wlp->session = NULL;
out:
        mutex_unlock(&wlp->mutex);
        return result;
}

/**
 * Enroll into WSS of provided WSSID by using neighbor as registrar
 *
 * &wss->mutex is held
 */
int wlp_enroll_neighbor(struct wlp *wlp, struct wlp_neighbor_e *neighbor,
                        struct wlp_wss *wss, struct wlp_uuid *wssid)
{
        int result = 0;
        struct device *dev = &wlp->rc->uwb_dev.dev;
        char buf[WLP_WSS_UUID_STRSIZE];
        struct uwb_dev_addr *dev_addr = &neighbor->uwb_dev->dev_addr;

        wlp_wss_uuid_print(buf, sizeof(buf), wssid);

        result =  wlp_d1d2_exchange(wlp, neighbor, wss, wssid);
        if (result < 0) {
                dev_err(dev, "WLP: D1/D2 message exchange for enrollment "
                        "failed. result = %d \n", result);
                goto out;
        }
        if (wss->state != WLP_WSS_STATE_PART_ENROLLED) {
                dev_err(dev, "WLP: Unable to enroll into WSS %s using "
                        "neighbor %02x:%02x. \n", buf,
                        dev_addr->data[1], dev_addr->data[0]);
                result = -EINVAL;
                goto out;
        }
        if (wss->secure_status == WLP_WSS_SECURE) {
                dev_err(dev, "FIXME: need to complete secure enrollment.\n");
                result = -EINVAL;
                goto error;
        } else {
                wss->state = WLP_WSS_STATE_ENROLLED;
                dev_dbg(dev, "WLP: Success Enrollment into unsecure WSS "
                        "%s using neighbor %02x:%02x. \n",
                        buf, dev_addr->data[1], dev_addr->data[0]);
        }
out:
        return result;
error:
        wlp_wss_reset(wss);
        return result;
}

/**
 * Discover WSS information of neighbor's active WSS
 */
static
int wlp_discover_neighbor(struct wlp *wlp,
                          struct wlp_neighbor_e *neighbor)
{
        return wlp_d1d2_exchange(wlp, neighbor, NULL, NULL);
}


/**
 * Each neighbor in the neighborhood cache is discoverable. Discover it.
 *
 * Discovery is done through sending of D1 association frame and parsing
 * the D2 association frame response. Only wssid from D2 will be included
 * in neighbor cache, rest is just displayed to user and forgotten.
 *
 * The discovery is not done in parallel. This is simple and enables us to
 * maintain only one association context.
 *
 * The discovery of one neighbor does not affect the other, but if the
 * discovery of a neighbor fails it is removed from the neighborhood cache.
 */
static
int wlp_discover_all_neighbors(struct wlp *wlp)
{
        int result = 0;
        struct device *dev = &wlp->rc->uwb_dev.dev;
        struct wlp_neighbor_e *neighbor, *next;

        list_for_each_entry_safe(neighbor, next, &wlp->neighbors, node) {
                result = wlp_discover_neighbor(wlp, neighbor);
                if (result < 0) {
                        dev_err(dev, "WLP: Unable to discover neighbor "
                                "%02x:%02x, removing from neighborhood. \n",
                                neighbor->uwb_dev->dev_addr.data[1],
                                neighbor->uwb_dev->dev_addr.data[0]);
                        __wlp_neighbor_release(neighbor);
                }
        }
        return result;
}

static int wlp_add_neighbor_helper(struct device *dev, void *priv)
{
        struct wlp *wlp = priv;
        struct uwb_dev *uwb_dev = to_uwb_dev(dev);

        return wlp_add_neighbor(wlp, uwb_dev);
}

/**
 * Discover WLP neighborhood
 *
 * Will send D1 association frame to all devices in beacon group that have
 * discoverable bit set in WLP IE. D2 frames will be received, information
 * displayed to user in @buf. Partial information (from D2 association
 * frame) will be cached to assist with future association
 * requests.
 *
 * The discovery of the WLP neighborhood is triggered by the user. This
 * should occur infrequently and we thus free current cache and re-allocate
 * memory if needed.
 *
 * If one neighbor fails during initial discovery (determining if it is a
 * neighbor or not), we fail all - note that interaction with neighbor has
 * not occured at this point so if a failure occurs we know something went wrong
 * locally. We thus undo everything.
 */
ssize_t wlp_discover(struct wlp *wlp)
{
        int result = 0;
        struct device *dev = &wlp->rc->uwb_dev.dev;

        mutex_lock(&wlp->nbmutex);
        /* Clear current neighborhood cache. */
        __wlp_neighbors_release(wlp);
        /* Determine which devices in neighborhood. Repopulate cache. */
        result = uwb_dev_for_each(wlp->rc, wlp_add_neighbor_helper, wlp);
        if (result < 0) {
                /* May have partial neighbor information, release all. */
                __wlp_neighbors_release(wlp);
                goto error_dev_for_each;
        }
        /* Discover the properties of devices in neighborhood. */
        result = wlp_discover_all_neighbors(wlp);
        /* In case of failure we still print our partial results. */
        if (result < 0) {
                dev_err(dev, "Unable to fully discover neighborhood. \n");
                result = 0;
        }
error_dev_for_each:
        mutex_unlock(&wlp->nbmutex);
        return result;
}

/**
 * Handle events from UWB stack
 *
 * We handle events conservatively. If a neighbor goes off the air we
 * remove it from the neighborhood. If an association process is in
 * progress this function will block waiting for the nbmutex to become
 * free. The association process will thus be allowed to complete before it
 * is removed.
 */
static
void wlp_uwb_notifs_cb(void *_wlp, struct uwb_dev *uwb_dev,
                       enum uwb_notifs event)
{
        struct wlp *wlp = _wlp;
        struct device *dev = &wlp->rc->uwb_dev.dev;
        struct wlp_neighbor_e *neighbor, *next;
        int result;
        switch (event) {
        case UWB_NOTIF_ONAIR:
                result = wlp_eda_create_node(&wlp->eda,
                                             uwb_dev->mac_addr.data,
                                             &uwb_dev->dev_addr);
                if (result < 0)
                        dev_err(dev, "WLP: Unable to add new neighbor "
                                "%02x:%02x to EDA cache.\n",
                                uwb_dev->dev_addr.data[1],
                                uwb_dev->dev_addr.data[0]);
                break;
        case UWB_NOTIF_OFFAIR:
                wlp_eda_rm_node(&wlp->eda, &uwb_dev->dev_addr);
                mutex_lock(&wlp->nbmutex);
                list_for_each_entry_safe(neighbor, next, &wlp->neighbors, node) {
                        if (neighbor->uwb_dev == uwb_dev)
                                __wlp_neighbor_release(neighbor);
                }
                mutex_unlock(&wlp->nbmutex);
                break;
        default:
                dev_err(dev, "don't know how to handle event %d from uwb\n",
                                event);
        }
}

static void wlp_channel_changed(struct uwb_pal *pal, int channel)
{
        struct wlp *wlp = container_of(pal, struct wlp, pal);

        if (channel < 0)
                netif_carrier_off(wlp->ndev);
        else
                netif_carrier_on(wlp->ndev);
}

int wlp_setup(struct wlp *wlp, struct uwb_rc *rc, struct net_device *ndev)
{
        int result;

        BUG_ON(wlp->fill_device_info == NULL);
        BUG_ON(wlp->xmit_frame == NULL);
        BUG_ON(wlp->stop_queue == NULL);
        BUG_ON(wlp->start_queue == NULL);

        wlp->rc = rc;
        wlp->ndev = ndev;
        wlp_eda_init(&wlp->eda);/* Set up address cache */
        wlp->uwb_notifs_handler.cb = wlp_uwb_notifs_cb;
        wlp->uwb_notifs_handler.data = wlp;
        uwb_notifs_register(rc, &wlp->uwb_notifs_handler);

        uwb_pal_init(&wlp->pal);
        wlp->pal.rc = rc;
        wlp->pal.channel_changed = wlp_channel_changed;
        result = uwb_pal_register(&wlp->pal);
        if (result < 0)
                uwb_notifs_deregister(wlp->rc, &wlp->uwb_notifs_handler);

        return result;
}
EXPORT_SYMBOL_GPL(wlp_setup);

void wlp_remove(struct wlp *wlp)
{
        wlp_neighbors_release(wlp);
        uwb_pal_unregister(&wlp->pal);
        uwb_notifs_deregister(wlp->rc, &wlp->uwb_notifs_handler);
        wlp_eda_release(&wlp->eda);
        mutex_lock(&wlp->mutex);
        if (wlp->dev_info != NULL)
                kfree(wlp->dev_info);
        mutex_unlock(&wlp->mutex);
        wlp->rc = NULL;
}
EXPORT_SYMBOL_GPL(wlp_remove);

/**
 * wlp_reset_all - reset the WLP hardware
 * @wlp: the WLP device to reset.
 *
 * This schedules a full hardware reset of the WLP device.  The radio
 * controller and any other PALs will also be reset.
 */
void wlp_reset_all(struct wlp *wlp)
{
        uwb_rc_reset_all(wlp->rc);
}
EXPORT_SYMBOL_GPL(wlp_reset_all);