1 files changed, 296 insertions, 0 deletions

diff --git a/net/mac80211/mesh_sync.c b/net/mac80211/mesh_sync.c
new file mode 100644
index 000000000000..f78b0139856f
--- /dev/null
+++ b/net/mac80211/mesh_sync.c
@@ -0,0 +1,296 @@
+/*
+ * Copyright 2011-2012, Pavel Zubarev <pavel.zubarev@gmail.com>
+ * Copyright 2011-2012, Marco Porsch <marco.porsch@s2005.tu-chemnitz.de>
+ * Copyright 2011-2012, cozybit Inc.
+ *
+ * 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.
+ */
+
+#include "ieee80211_i.h"
+#include "mesh.h"
+#include "driver-ops.h"
+
+#ifdef CONFIG_MAC80211_VERBOSE_MESH_SYNC_DEBUG
+#define msync_dbg(fmt, args...) \
+        printk(KERN_DEBUG "Mesh sync (%s): " fmt "\n", sdata->name, ##args)
+#else
+#define msync_dbg(fmt, args...)   do { (void)(0); } while (0)
+#endif
+
+/* This is not in the standard.  It represents a tolerable tbtt drift below
+ * which we do no TSF adjustment.
+ */
+#define TBTT_MINIMUM_ADJUSTMENT 10
+
+struct sync_method {
+        u8 method;
+        struct ieee80211_mesh_sync_ops ops;
+};
+
+/**
+ * mesh_peer_tbtt_adjusting - check if an mp is currently adjusting its TBTT
+ *
+ * @ie: information elements of a management frame from the mesh peer
+ */
+static bool mesh_peer_tbtt_adjusting(struct ieee802_11_elems *ie)
+{
+        return (ie->mesh_config->meshconf_cap &
+            MESHCONF_CAPAB_TBTT_ADJUSTING) != 0;
+}
+
+void mesh_sync_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
+{
+        struct ieee80211_local *local = sdata->local;
+        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+        /* sdata->vif.bss_conf.beacon_int in 1024us units, 0.04% */
+        u64 beacon_int_fraction = sdata->vif.bss_conf.beacon_int * 1024 / 2500;
+        u64 tsf;
+        u64 tsfdelta;
+
+        spin_lock_bh(&ifmsh->sync_offset_lock);
+
+        if (ifmsh->sync_offset_clockdrift_max < beacon_int_fraction) {
+                msync_dbg("TBTT : max clockdrift=%lld; adjusting",
+                        (long long) ifmsh->sync_offset_clockdrift_max);
+                tsfdelta = -ifmsh->sync_offset_clockdrift_max;
+                ifmsh->sync_offset_clockdrift_max = 0;
+        } else {
+                msync_dbg("TBTT : max clockdrift=%lld; adjusting by %llu",
+                        (long long) ifmsh->sync_offset_clockdrift_max,
+                        (unsigned long long) beacon_int_fraction);
+                tsfdelta = -beacon_int_fraction;
+                ifmsh->sync_offset_clockdrift_max -= beacon_int_fraction;
+        }
+
+        tsf = drv_get_tsf(local, sdata);
+        if (tsf != -1ULL)
+                drv_set_tsf(local, sdata, tsf + tsfdelta);
+        spin_unlock_bh(&ifmsh->sync_offset_lock);
+}
+
+static void mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
+                                   u16 stype,
+                                   struct ieee80211_mgmt *mgmt,
+                                   struct ieee802_11_elems *elems,
+                                   struct ieee80211_rx_status *rx_status)
+{
+        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+        struct ieee80211_local *local = sdata->local;
+        struct sta_info *sta;
+        u64 t_t, t_r;
+
+        WARN_ON(ifmsh->mesh_sp_id != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
+
+        /* standard mentions only beacons */
+        if (stype != IEEE80211_STYPE_BEACON)
+                return;
+
+        /* The current tsf is a first approximation for the timestamp
+         * for the received beacon.  Further down we try to get a
+         * better value from the rx_status->mactime field if
+         * available. Also we have to call drv_get_tsf() before
+         * entering the rcu-read section.*/
+        t_r = drv_get_tsf(local, sdata);
+
+        rcu_read_lock();
+        sta = sta_info_get(sdata, mgmt->sa);
+        if (!sta)
+                goto no_sync;
+
+        /* check offset sync conditions (13.13.2.2.1)
+         *
+         * TODO also sync to
+         * dot11MeshNbrOffsetMaxNeighbor non-peer non-MBSS neighbors
+         */
+
+        if (elems->mesh_config && mesh_peer_tbtt_adjusting(elems)) {
+                clear_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
+                msync_dbg("STA %pM : is adjusting TBTT", sta->sta.addr);
+                goto no_sync;
+        }
+
+        if (rx_status->flag & RX_FLAG_MACTIME_MPDU && rx_status->mactime) {
+                /*
+                 * The mactime is defined as the time the first data symbol
+                 * of the frame hits the PHY, and the timestamp of the beacon
+                 * is defined as "the time that the data symbol containing the
+                 * first bit of the timestamp is transmitted to the PHY plus
+                 * the transmitting STA's delays through its local PHY from the
+                 * MAC-PHY interface to its interface with the WM" (802.11
+                 * 11.1.2)
+                 *
+                 * T_r, in 13.13.2.2.2, is just defined as "the frame reception
+                 * time" but we unless we interpret that time to be the same
+                 * time of the beacon timestamp, the offset calculation will be
+                 * off.  Below we adjust t_r to be "the time at which the first
+                 * symbol of the timestamp element in the beacon is received".
+                 * This correction depends on the rate.
+                 *
+                 * Based on similar code in ibss.c
+                 */
+                int rate;
+
+                if (rx_status->flag & RX_FLAG_HT) {
+                        /* TODO:
+                         * In principle there could be HT-beacons (Dual Beacon
+                         * HT Operation options), but for now ignore them and
+                         * just use the primary (i.e. non-HT) beacons for
+                         * synchronization.
+                         * */
+                        goto no_sync;
+                } else
+                        rate = local->hw.wiphy->bands[rx_status->band]->
+                                bitrates[rx_status->rate_idx].bitrate;
+
+                /* 24 bytes of header * 8 bits/byte *
+                 * 10*(100 Kbps)/Mbps / rate (100 Kbps)*/
+                t_r = rx_status->mactime + (24 * 8 * 10 / rate);
+        }
+
+        /* Timing offset calculation (see 13.13.2.2.2) */
+        t_t = le64_to_cpu(mgmt->u.beacon.timestamp);
+        sta->t_offset = t_t - t_r;
+
+        if (test_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN)) {
+                s64 t_clockdrift = sta->t_offset_setpoint
+                                   - sta->t_offset;
+
+                msync_dbg("STA %pM : sta->t_offset=%lld,"
+                          " sta->t_offset_setpoint=%lld,"
+                          " t_clockdrift=%lld",
+                          sta->sta.addr,
+                          (long long) sta->t_offset,
+                          (long long)
+                          sta->t_offset_setpoint,
+                          (long long) t_clockdrift);
+                rcu_read_unlock();
+
+                spin_lock_bh(&ifmsh->sync_offset_lock);
+                if (t_clockdrift >
+                    ifmsh->sync_offset_clockdrift_max)
+                        ifmsh->sync_offset_clockdrift_max
+                                = t_clockdrift;
+                spin_unlock_bh(&ifmsh->sync_offset_lock);
+
+        } else {
+                sta->t_offset_setpoint = sta->t_offset;
+                set_sta_flag(sta, WLAN_STA_TOFFSET_KNOWN);
+                msync_dbg("STA %pM : offset was invalid, "
+                          " sta->t_offset=%lld",
+                          sta->sta.addr,
+                          (long long) sta->t_offset);
+                rcu_read_unlock();
+        }
+        return;
+
+no_sync:
+        rcu_read_unlock();
+}
+
+static void mesh_sync_offset_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
+{
+        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+
+        WARN_ON(ifmsh->mesh_sp_id
+                != IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET);
+        BUG_ON(!rcu_read_lock_held());
+
+        spin_lock_bh(&ifmsh->sync_offset_lock);
+
+        if (ifmsh->sync_offset_clockdrift_max >
+                TBTT_MINIMUM_ADJUSTMENT) {
+                /* Since ajusting the tsf here would
+                 * require a possibly blocking call
+                 * to the driver tsf setter, we punt
+                 * the tsf adjustment to the mesh tasklet
+                 */
+                msync_dbg("TBTT : kicking off TBTT "
+                          "adjustment with "
+                          "clockdrift_max=%lld",
+                  ifmsh->sync_offset_clockdrift_max);
+                set_bit(MESH_WORK_DRIFT_ADJUST,
+                        &ifmsh->wrkq_flags);
+        } else {
+                msync_dbg("TBTT : max clockdrift=%lld; "
+                          "too small to adjust",
+                          (long long)
+                       ifmsh->sync_offset_clockdrift_max);
+                ifmsh->sync_offset_clockdrift_max = 0;
+        }
+        spin_unlock_bh(&ifmsh->sync_offset_lock);
+}
+
+static const u8 *mesh_get_vendor_oui(struct ieee80211_sub_if_data *sdata)
+{
+        struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+        u8 offset;
+
+        if (!ifmsh->ie || !ifmsh->ie_len)
+                return NULL;
+
+        offset = ieee80211_ie_split_vendor(ifmsh->ie,
+                                        ifmsh->ie_len, 0);
+
+        if (!offset)
+                return NULL;
+
+        return ifmsh->ie + offset + 2;
+}
+
+static void mesh_sync_vendor_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
+                                   u16 stype,
+                                   struct ieee80211_mgmt *mgmt,
+                                   struct ieee802_11_elems *elems,
+                                   struct ieee80211_rx_status *rx_status)
+{
+        const u8 *oui;
+
+        WARN_ON(sdata->u.mesh.mesh_sp_id != IEEE80211_SYNC_METHOD_VENDOR);
+        msync_dbg("called mesh_sync_vendor_rx_bcn_presp");
+        oui = mesh_get_vendor_oui(sdata);
+        /*  here you would implement the vendor offset tracking for this oui */
+}
+
+static void mesh_sync_vendor_adjust_tbtt(struct ieee80211_sub_if_data *sdata)
+{
+        const u8 *oui;
+
+        WARN_ON(sdata->u.mesh.mesh_sp_id != IEEE80211_SYNC_METHOD_VENDOR);
+        msync_dbg("called mesh_sync_vendor_adjust_tbtt");
+        oui = mesh_get_vendor_oui(sdata);
+        /*  here you would implement the vendor tsf adjustment for this oui */
+}
+
+/* global variable */
+static struct sync_method sync_methods[] = {
+        {
+                .method = IEEE80211_SYNC_METHOD_NEIGHBOR_OFFSET,
+                .ops = {
+                        .rx_bcn_presp = &mesh_sync_offset_rx_bcn_presp,
+                        .adjust_tbtt = &mesh_sync_offset_adjust_tbtt,
+                }
+        },
+        {
+                .method = IEEE80211_SYNC_METHOD_VENDOR,
+                .ops = {
+                        .rx_bcn_presp = &mesh_sync_vendor_rx_bcn_presp,
+                        .adjust_tbtt = &mesh_sync_vendor_adjust_tbtt,
+                }
+        },
+};
+
+struct ieee80211_mesh_sync_ops *ieee80211_mesh_sync_ops_get(u8 method)
+{
+        struct ieee80211_mesh_sync_ops *ops = NULL;
+        u8 i;
+
+        for (i = 0 ; i < ARRAY_SIZE(sync_methods); ++i) {
+                if (sync_methods[i].method == method) {
+                        ops = &sync_methods[i].ops;
+                        break;
+                }
+        }
+        return ops;
+}