rt2x00: Add autowake support for USB hardware

The USB drivers don't support automatically waking up when in powersaving mode,
add a work object which will wakeup the device in time to receive the next beacon.
Based on that beacon, we either go back into powersaving mode, or we remain awake
to receive the buffered frames for our station.

Some part of the code, especially rt2x00lib_find_ie and rt2x00lib_rxdone_check_ps
are inspired on the code from carl9170.

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 88 insertions, 0 deletions

diff --git a/drivers/net/wireless/rt2x00/rt2x00dev.c b/drivers/net/wireless/rt2x00/rt2x00dev.c
index 7776d9f1f297..2eb5196977fd 100644
--- a/drivers/net/wireless/rt2x00/rt2x00dev.c
+++ b/drivers/net/wireless/rt2x00/rt2x00dev.c
@@ -141,6 +141,16 @@ static void rt2x00lib_intf_scheduled(struct work_struct *work)
                                             rt2x00dev);
 }
 
+static void rt2x00lib_autowakeup(struct work_struct *work)
+{
+        struct rt2x00_dev *rt2x00dev =
+            container_of(work, struct rt2x00_dev, autowakeup_work.work);
+
+        if (rt2x00dev->ops->lib->set_device_state(rt2x00dev, STATE_AWAKE))
+                ERROR(rt2x00dev, "Device failed to wakeup.\n");
+        clear_bit(CONFIG_POWERSAVING, &rt2x00dev->flags);
+}
+
 /*
  * Interrupt context handlers.
  */
@@ -416,6 +426,77 @@ void rt2x00lib_txdone_noinfo(struct queue_entry *entry, u32 status)
 }
 EXPORT_SYMBOL_GPL(rt2x00lib_txdone_noinfo);
 
+static u8 *rt2x00lib_find_ie(u8 *data, unsigned int len, u8 ie)
+{
+        struct ieee80211_mgmt *mgmt = (void *)data;
+        u8 *pos, *end;
+
+        pos = (u8 *)mgmt->u.beacon.variable;
+        end = data + len;
+        while (pos < end) {
+                if (pos + 2 + pos[1] > end)
+                        return NULL;
+
+                if (pos[0] == ie)
+                        return pos;
+
+                pos += 2 + pos[1];
+        }
+
+        return NULL;
+}
+
+static void rt2x00lib_rxdone_check_ps(struct rt2x00_dev *rt2x00dev,
+                                      struct sk_buff *skb,
+                                      struct rxdone_entry_desc *rxdesc)
+{
+        struct ieee80211_hdr *hdr = (void *) skb->data;
+        struct ieee80211_tim_ie *tim_ie;
+        u8 *tim;
+        u8 tim_len;
+        bool cam;
+
+        /* If this is not a beacon, or if mac80211 has no powersaving
+         * configured, or if the device is already in powersaving mode
+         * we can exit now. */
+        if (likely(!ieee80211_is_beacon(hdr->frame_control) ||
+                   !(rt2x00dev->hw->conf.flags & IEEE80211_CONF_PS)))
+                return;
+
+        /* min. beacon length + FCS_LEN */
+        if (skb->len <= 40 + FCS_LEN)
+                return;
+
+        /* and only beacons from the associated BSSID, please */
+        if (!(rxdesc->dev_flags & RXDONE_MY_BSS) ||
+            !rt2x00dev->aid)
+                return;
+
+        rt2x00dev->last_beacon = jiffies;
+
+        tim = rt2x00lib_find_ie(skb->data, skb->len - FCS_LEN, WLAN_EID_TIM);
+        if (!tim)
+                return;
+
+        if (tim[1] < sizeof(*tim_ie))
+                return;
+
+        tim_len = tim[1];
+        tim_ie = (struct ieee80211_tim_ie *) &tim[2];
+
+        /* Check whenever the PHY can be turned off again. */
+
+        /* 1. What about buffered unicast traffic for our AID? */
+        cam = ieee80211_check_tim(tim_ie, tim_len, rt2x00dev->aid);
+
+        /* 2. Maybe the AP wants to send multicast/broadcast data? */
+        cam |= (tim_ie->bitmap_ctrl & 0x01);
+
+        if (!cam && !test_bit(CONFIG_POWERSAVING, &rt2x00dev->flags))
+                rt2x00lib_config(rt2x00dev, &rt2x00dev->hw->conf,
+                                 IEEE80211_CONF_CHANGE_PS);
+}
+
 static int rt2x00lib_rxdone_read_signal(struct rt2x00_dev *rt2x00dev,
                                         struct rxdone_entry_desc *rxdesc)
 {
@@ -531,6 +612,12 @@ void rt2x00lib_rxdone(struct queue_entry *entry)
                 rxdesc.flags |= RX_FLAG_HT;
 
         /*
+         * Check if this is a beacon, and more frames have been
+         * buffered while we were in powersaving mode.
+         */
+        rt2x00lib_rxdone_check_ps(rt2x00dev, entry->skb, &rxdesc);
+
+        /*
          * Update extra components
          */
         rt2x00link_update_stats(rt2x00dev, entry->skb, &rxdesc);
@@ -1017,6 +1104,7 @@ int rt2x00lib_probe_dev(struct rt2x00_dev *rt2x00dev)
         }
 
         INIT_WORK(&rt2x00dev->intf_work, rt2x00lib_intf_scheduled);
+        INIT_DELAYED_WORK(&rt2x00dev->autowakeup_work, rt2x00lib_autowakeup);
 
         /*
          * Let the driver probe the device to detect the capabilities.