rt2x00: Add guardian byte for beacons

index 49e70ca..1ea6696 100644
@@ -1751,18 +1751,30 @@ static void rt2500usb_beacondone(struct work_struct *work)
 {
 	struct data_ring *ring =
 		container_of(work, struct data_ring, irq_work);
-	struct rt2x00_dev *rt2x00dev = ring->rt2x00dev;
-	struct data_entry *entry = rt2x00_get_data_entry(ring);
-	struct sk_buff *skb;
+	struct data_entry *entry;
 
-	skb = ieee80211_beacon_get(rt2x00dev->hw,
-		rt2x00dev->interface.id, &entry->tx_status.control);
-	if (!skb)
+	if (!GET_FLAG(ring->rt2x00dev, DEVICE_ENABLED_RADIO))
 		return;
 
-	rt2500usb_beacon_update(rt2x00dev->hw, skb, &entry->tx_status.control);
-
-	dev_kfree_skb_any(skb);
+	/*
+	 * Check if this was the guardian beacon,
+	 * if that was the case we need to send the real beacon now.
+	 * Otherwise we should free the sk_buffer, the device
+	 * should be doing the rest of the work now.
+	 */
+	if (ring->index == 1) {
+		rt2x00_ring_index_done_inc(ring);
+		entry = rt2x00_get_data_entry(ring);
+		usb_submit_urb(entry->priv, GFP_ATOMIC);
+		rt2x00_ring_index_inc(ring);
+	} else if (ring->index_done == 1) {
+		entry = rt2x00_get_data_entry_done(ring);
+		if (entry->skb) {
+			dev_kfree_skb(entry->skb);
+			entry->skb = NULL;
+		}
+		rt2x00_ring_index_done_inc(ring);
+	}
 }
 
 static void rt2500usb_rxdone(struct work_struct *work)

@@ -2401,9 +2413,11 @@ static int rt2500usb_beacon_update(struct ieee80211_hw *hw,
 	struct rt2x00_dev *rt2x00dev = hw->priv;
 	struct usb_device *usb_dev =
 		interface_to_usbdev(rt2x00dev_usb(rt2x00dev));
-	struct data_entry *entry;
-
-	entry = rt2x00_get_data_entry(&rt2x00dev->ring[RING_BEACON]);
+	struct data_ring *ring = &rt2x00dev->ring[RING_BEACON];
+	struct data_entry *beacon;
+	struct data_entry *guardian;
+	int length;
+	u16 reg;
 
 	/*
 	 * Just in case the ieee80211 doesn't set this,

@@ -2413,22 +2427,79 @@ static int rt2500usb_beacon_update(struct ieee80211_hw *hw,
 	control->queue = IEEE80211_TX_QUEUE_BEACON;
 
 	/*
-	 * Update the beacon entry.
+	 * Obtain 2 entries, one for the guardian byte,
+	 * the second for the actual beacon.
 	 */
-	memcpy(rt2x00_txdata_addr(entry), skb->data, skb->len);
-	rt2500usb_write_tx_desc(rt2x00dev, rt2x00_txdesc_addr(entry),
-		(struct ieee80211_hdr *)skb->data, skb->len, control);
+	guardian = rt2x00_get_data_entry(ring);
+	rt2x00_ring_index_inc(ring);
+	beacon = rt2x00_get_data_entry(ring);
+
+	/*
+	 * First we create the beacon.
+	 */
+	skb_push(skb, ring->desc_size);
+	rt2500usb_write_tx_desc(rt2x00dev,
+		(struct data_desc*)skb->data,
+		(struct ieee80211_hdr*)(skb->data + ring->desc_size),
+		skb->len - ring->desc_size,
+		control);
+
+	/*
+	 * Length passed to usb_fill_urb cannot be an odd number,
+	 * so add 1 byte to make it even.
+	 */
+	length = skb->len;
+	if (length % 2)
+		length++;
 
-	SET_FLAG(entry, ENTRY_OWNER_NIC);
 	usb_fill_bulk_urb(
-		rt2x00_urb(entry),
+		beacon->priv,
 		usb_dev,
 		usb_sndbulkpipe(usb_dev, 1),
-		entry->data_addr,
-		skb->len + rt2x00dev->ring[RING_BEACON].desc_size,
+		skb->data,
+		length,
 		rt2500usb_interrupt,
-		entry);
-	usb_submit_urb(rt2x00_urb(entry), GFP_ATOMIC);
+		beacon);
+
+	beacon->skb = skb;
+
+	/*
+	 * Second we need to create the guardian byte.
+	 * We only need a single byte, so lets recycle
+	 * the 'flags' field we are not using for beacons.
+	 */
+	guardian->reg = 0;
+	usb_fill_bulk_urb(
+		guardian->priv,
+		usb_dev,
+		usb_sndbulkpipe(usb_dev, 1),
+		&guardian->reg,
+		1,
+		rt2500usb_interrupt,
+		guardian);
+
+	/*
+	 * Send out the guardian byte.
+	 */
+	usb_submit_urb(guardian->priv, GFP_ATOMIC);
+
+	/*
+	 * Enable beacon generation.
+	 */
+	rt2x00_register_read(rt2x00dev, TXRX_CSR19, &reg);
+	if (!rt2x00_get_field16(reg, TXRX_CSR19_BEACON_GEN)) {
+		rt2x00_set_field16(&reg, TXRX_CSR19_BEACON_GEN, 1);
+		/*
+		 * Beacon generation will fail initially.
+		 * To prevent this we need to register the TXRX_CSR19
+		 * register several times.
+		 */
+		rt2x00_register_write(rt2x00dev, TXRX_CSR19, reg);
+		rt2x00_register_write(rt2x00dev, TXRX_CSR19, 0);
+		rt2x00_register_write(rt2x00dev, TXRX_CSR19, reg);
+		rt2x00_register_write(rt2x00dev, TXRX_CSR19, 0);
+		rt2x00_register_write(rt2x00dev, TXRX_CSR19, reg);
+	}
 
 	return 0;
 }

index d6e968c..b79f860 100644
@@ -525,6 +525,11 @@ struct data_entry {
 #define ENTRY_RTS_CTS_FRAME	0x00000002
 
 	/*
+	 * extra register field
+	 */
+	unsigned int reg;
+
+	/*
 	 * Ring we belong to.
 	 */
 	struct data_ring *ring;

index a0dc726..b4f2961 100644
@@ -78,4 +78,10 @@
  */
 #define LINK_TUNE_INTERVAL	( 1 * HZ )
 
+/*
+ * USB devices need an additional Beacon (guardian beacon) to be generated.
+ */
+#undef BEACON_ENTRIES
+#define BEACON_ENTRIES 2
+
 #endif /* RT2X00USB_H */

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