mac80211: tell driver when idle

When we aren't doing anything in mac80211, we can turn off
much of the hardware, depending on the driver/hw. Not doing
anything, aka being idle, means:

 * no monitor interfaces
 * no AP/mesh/wds interfaces
 * any station interfaces are in DISABLED state
 * any IBSS interfaces aren't trying to be in a network
 * we aren't trying to scan

By creating a new function that verifies these conditions and calling
it at strategic points where the states of those conditions change,
we can easily make mac80211 tell the driver when we are idle to save
power.

Additionally, this fixes a small quirk where a recalculated powersave
state is passed to the driver even if the hardware is about to stopped
completely.

This patch intentionally doesn't touch radio_enabled because that is
currently implemented to be a soft rfkill which is inappropriate here
when we need to be able to wake up with low latency.

One thing I'm not entirely sure about is this:

  phy0: device no longer idle - in use
  wlan0: direct probe to AP 00:11:24:91:07:4d try 1
  wlan0 direct probe responded
  wlan0: authenticate with AP 00:11:24:91:07:4d
  wlan0: authenticated
> phy0: device now idle
> phy0: device no longer idle - in use
  wlan0: associate with AP 00:11:24:91:07:4d
  wlan0: RX AssocResp from 00:11:24:91:07:4d (capab=0x401 status=0 aid=1)
  wlan0: associated

Is it appropriate to go into idle state for a short time when we have
just authenticated, but not associated yet? This happens only with the
userspace SME, because we cannot really know how long it will wait
before asking us to associate. Would going idle after a short timeout
be more appropriate? We may need to revisit this, depending on what
happens.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 76 insertions, 2 deletions

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 256fa19e14ec..8b6daf0219f4 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -301,6 +301,8 @@ static int ieee80211_open(struct net_device *dev)
         if (sdata->flags & IEEE80211_SDATA_PROMISC)
                 atomic_inc(&local->iff_promiscs);
 
+        hw_reconf_flags |= __ieee80211_recalc_idle(local);
+
         local->open_count++;
         if (hw_reconf_flags) {
                 ieee80211_hw_config(local, hw_reconf_flags);
@@ -548,6 +550,10 @@ static int ieee80211_stop(struct net_device *dev)
 
         sdata->bss = NULL;
 
+        hw_reconf_flags |= __ieee80211_recalc_idle(local);
+
+        ieee80211_recalc_ps(local, -1);
+
         if (local->open_count == 0) {
                 if (netif_running(local->mdev))
                         dev_close(local->mdev);
@@ -565,8 +571,6 @@ static int ieee80211_stop(struct net_device *dev)
                 hw_reconf_flags = 0;
         }
 
-        ieee80211_recalc_ps(local, -1);
-
         /* do after stop to avoid reconfiguring when we stop anyway */
         if (hw_reconf_flags)
                 ieee80211_hw_config(local, hw_reconf_flags);
@@ -892,3 +896,73 @@ void ieee80211_remove_interfaces(struct ieee80211_local *local)
                 unregister_netdevice(sdata->dev);
         }
 }
+
+static u32 ieee80211_idle_off(struct ieee80211_local *local,
+                              const char *reason)
+{
+        if (!(local->hw.conf.flags & IEEE80211_CONF_IDLE))
+                return 0;
+
+#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
+        printk(KERN_DEBUG "%s: device no longer idle - %s\n",
+               wiphy_name(local->hw.wiphy), reason);
+#endif
+
+        local->hw.conf.flags &= ~IEEE80211_CONF_IDLE;
+        return IEEE80211_CONF_CHANGE_IDLE;
+}
+
+static u32 ieee80211_idle_on(struct ieee80211_local *local)
+{
+        if (local->hw.conf.flags & IEEE80211_CONF_IDLE)
+                return 0;
+
+#ifdef CONFIG_MAC80211_VERBOSE_DEBUG
+        printk(KERN_DEBUG "%s: device now idle\n",
+               wiphy_name(local->hw.wiphy));
+#endif
+
+        local->hw.conf.flags |= IEEE80211_CONF_IDLE;
+        return IEEE80211_CONF_CHANGE_IDLE;
+}
+
+u32 __ieee80211_recalc_idle(struct ieee80211_local *local)
+{
+        struct ieee80211_sub_if_data *sdata;
+        int count = 0;
+
+        if (local->hw_scanning || local->sw_scanning)
+                return ieee80211_idle_off(local, "scanning");
+
+        list_for_each_entry(sdata, &local->interfaces, list) {
+                if (!netif_running(sdata->dev))
+                        continue;
+                /* do not count disabled managed interfaces */
+                if (sdata->vif.type == NL80211_IFTYPE_STATION &&
+                    sdata->u.mgd.state == IEEE80211_STA_MLME_DISABLED)
+                        continue;
+                /* do not count unused IBSS interfaces */
+                if (sdata->vif.type == NL80211_IFTYPE_ADHOC &&
+                    !sdata->u.ibss.ssid_len)
+                        continue;
+                /* count everything else */
+                count++;
+        }
+
+        if (!count)
+                return ieee80211_idle_on(local);
+        else
+                return ieee80211_idle_off(local, "in use");
+
+        return 0;
+}
+
+void ieee80211_recalc_idle(struct ieee80211_local *local)
+{
+        u32 chg;
+
+        mutex_lock(&local->iflist_mtx);
+        chg = __ieee80211_recalc_idle(local);
+        mutex_unlock(&local->iflist_mtx);
+        ieee80211_hw_config(local, chg);
+}