rt2x00: Report RX end time for rt2400pci

rt2400 is the only currently available rt2x00 driver which
supports reporting of the RX end time for frames.
Since mac80211 uses this information for IBSS syncing, it
is important that it is being reported.

v2: Complement 32 bits of RX timestamp with upper 32bits from TSF

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

drivers/net/wireless/rt2x00/rt2400pci.c

@@ -1087,25 +1087,48 @@ static void rt2400pci_kick_tx_queue(struct rt2x00_dev *rt2x00dev,
 static void rt2400pci_fill_rxdone(struct queue_entry *entry,
 				  struct rxdone_entry_desc *rxdesc)
 {
+	struct rt2x00_dev *rt2x00dev = entry->queue->rt2x00dev;
 	struct queue_entry_priv_pci *entry_priv = entry->priv_data;
 	u32 word0;
 	u32 word2;
 	u32 word3;
+	u32 word4;
+	u64 tsf;
+	u32 rx_low;
+	u32 rx_high;
 
 	rt2x00_desc_read(entry_priv->desc, 0, &word0);
 	rt2x00_desc_read(entry_priv->desc, 2, &word2);
 	rt2x00_desc_read(entry_priv->desc, 3, &word3);
+	rt2x00_desc_read(entry_priv->desc, 4, &word4);
 
 	if (rt2x00_get_field32(word0, RXD_W0_CRC_ERROR))
 		rxdesc->flags |= RX_FLAG_FAILED_FCS_CRC;
 	if (rt2x00_get_field32(word0, RXD_W0_PHYSICAL_ERROR))
 		rxdesc->flags |= RX_FLAG_FAILED_PLCP_CRC;
 
+	/*
+	 * We only get the lower 32bits from the timestamp,
+	 * to get the full 64bits we must complement it with
+	 * the timestamp from get_tsf().
+	 * Note that when a wraparound of the lower 32bits
+	 * has occurred between the frame arrival and the get_tsf()
+	 * call, we must decrease the higher 32bits with 1 to get
+	 * to correct value.
+	 */
+	tsf = rt2x00dev->ops->hw->get_tsf(rt2x00dev->hw);
+	rx_low = rt2x00_get_field32(word4, RXD_W4_RX_END_TIME);
+	rx_high = upper_32_bits(tsf);
+
+	if ((u32)tsf <= rx_low)
+		rx_high--;
+
 	/*
 	 * Obtain the status about this packet.
 	 * The signal is the PLCP value, and needs to be stripped
 	 * of the preamble bit (0x08).
 	 */
+	rxdesc->timestamp = ((u64)rx_high << 32) | rx_low;
 	rxdesc->signal = rt2x00_get_field32(word2, RXD_W2_SIGNAL) & ~0x08;
 	rxdesc->rssi = rt2x00_get_field32(word2, RXD_W3_RSSI) -
 	    entry->queue->rt2x00dev->rssi_offset;

drivers/net/wireless/rt2x00/rt2x00dev.c

@@ -664,6 +664,7 @@ void rt2x00lib_rxdone(struct rt2x00_dev *rt2x00dev,
 
 	rt2x00dev->link.qual.rx_success++;
 
+	rx_status->mactime = rxdesc.timestamp;
 	rx_status->rate_idx = idx;
 	rx_status->qual =
 	    rt2x00lib_calculate_link_signal(rt2x00dev, rxdesc.rssi);

drivers/net/wireless/rt2x00/rt2x00queue.h

@@ -146,6 +146,7 @@ enum rxdone_entry_desc_flags {
  *
  * Summary of information that has been read from the RX frame descriptor.
  *
+ * @timestamp: RX Timestamp
  * @signal: Signal of the received frame.
  * @rssi: RSSI of the received frame.
  * @size: Data size of the received frame.
@@ -154,6 +155,7 @@ enum rxdone_entry_desc_flags {
 
  */
 struct rxdone_entry_desc {
+	u64 timestamp;
 	int signal;
 	int rssi;
 	int size;