gianfar: Add hardware TX timestamping support

If a packet has the skb_shared_tx->hardware flag set the device is
instructed to generate a TX timestamp and write it back to memory after
the frame is transmitted. During the clean_tx_ring operation the
timestamp will be extracted and copied into the skb_shared_hwtstamps
struct of the skb.

TX timestamping is enabled by setting the tx_type to something else
than HWTSTAMP_TX_OFF with the SIOCSHWTSTAMP ioctl command. It is only
supported by eTSEC devices.

Signed-off-by: Manfred Rudigier <manfred.rudigier@omicron.at>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 101 insertions, 20 deletions

diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
index d102484c4b36..032073d1e3d2 100644
--- a/drivers/net/gianfar.c
+++ b/drivers/net/gianfar.c
@@ -795,8 +795,18 @@ static int gfar_hwtstamp_ioctl(struct net_device *netdev,
         if (config.flags)
                 return -EINVAL;
 
-        if (config.tx_type)
+        switch (config.tx_type) {
+        case HWTSTAMP_TX_OFF:
+                priv->hwts_tx_en = 0;
+                break;
+        case HWTSTAMP_TX_ON:
+                if (!(priv->device_flags & FSL_GIANFAR_DEV_HAS_TIMER))
+                        return -ERANGE;
+                priv->hwts_tx_en = 1;
+                break;
+        default:
                 return -ERANGE;
+        }
 
         switch (config.rx_filter) {
         case HWTSTAMP_FILTER_NONE:
@@ -1972,23 +1982,29 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
         struct netdev_queue *txq;
         struct gfar __iomem *regs = NULL;
         struct txfcb *fcb = NULL;
-        struct txbd8 *txbdp, *txbdp_start, *base;
+        struct txbd8 *txbdp, *txbdp_start, *base, *txbdp_tstamp = NULL;
         u32 lstatus;
-        int i, rq = 0;
+        int i, rq = 0, do_tstamp = 0;
         u32 bufaddr;
         unsigned long flags;
-        unsigned int nr_frags, length;
-
+        unsigned int nr_frags, nr_txbds, length;
+        union skb_shared_tx *shtx;
 
         rq = skb->queue_mapping;
         tx_queue = priv->tx_queue[rq];
         txq = netdev_get_tx_queue(dev, rq);
         base = tx_queue->tx_bd_base;
         regs = tx_queue->grp->regs;
+        shtx = skb_tx(skb);
+
+        /* check if time stamp should be generated */
+        if (unlikely(shtx->hardware && priv->hwts_tx_en))
+                do_tstamp = 1;
 
         /* make space for additional header when fcb is needed */
         if (((skb->ip_summed == CHECKSUM_PARTIAL) ||
-                        (priv->vlgrp && vlan_tx_tag_present(skb))) &&
+                        (priv->vlgrp && vlan_tx_tag_present(skb)) ||
+                        unlikely(do_tstamp)) &&
                         (skb_headroom(skb) < GMAC_FCB_LEN)) {
                 struct sk_buff *skb_new;
 
@@ -2005,8 +2021,14 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
         /* total number of fragments in the SKB */
         nr_frags = skb_shinfo(skb)->nr_frags;
 
+        /* calculate the required number of TxBDs for this skb */
+        if (unlikely(do_tstamp))
+                nr_txbds = nr_frags + 2;
+        else
+                nr_txbds = nr_frags + 1;
+
         /* check if there is space to queue this packet */
-        if ((nr_frags+1) > tx_queue->num_txbdfree) {
+        if (nr_txbds > tx_queue->num_txbdfree) {
                 /* no space, stop the queue */
                 netif_tx_stop_queue(txq);
                 dev->stats.tx_fifo_errors++;
@@ -2018,9 +2040,19 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
         txq->tx_packets ++;
 
         txbdp = txbdp_start = tx_queue->cur_tx;
+        lstatus = txbdp->lstatus;
+
+        /* Time stamp insertion requires one additional TxBD */
+        if (unlikely(do_tstamp))
+                txbdp_tstamp = txbdp = next_txbd(txbdp, base,
+                                tx_queue->tx_ring_size);
 
         if (nr_frags == 0) {
-                lstatus = txbdp->lstatus | BD_LFLAG(TXBD_LAST | TXBD_INTERRUPT);
+                if (unlikely(do_tstamp))
+                        txbdp_tstamp->lstatus |= BD_LFLAG(TXBD_LAST |
+                                        TXBD_INTERRUPT);
+                else
+                        lstatus |= BD_LFLAG(TXBD_LAST | TXBD_INTERRUPT);
         } else {
                 /* Place the fragment addresses and lengths into the TxBDs */
                 for (i = 0; i < nr_frags; i++) {
@@ -2066,11 +2098,32 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
                 gfar_tx_vlan(skb, fcb);
         }
 
-        /* setup the TxBD length and buffer pointer for the first BD */
+        /* Setup tx hardware time stamping if requested */
+        if (unlikely(do_tstamp)) {
+                shtx->in_progress = 1;
+                if (fcb == NULL)
+                        fcb = gfar_add_fcb(skb);
+                fcb->ptp = 1;
+                lstatus |= BD_LFLAG(TXBD_TOE);
+        }
+
         txbdp_start->bufPtr = dma_map_single(&priv->ofdev->dev, skb->data,
                         skb_headlen(skb), DMA_TO_DEVICE);
 
-        lstatus |= BD_LFLAG(TXBD_CRC | TXBD_READY) | skb_headlen(skb);
+        /*
+         * If time stamping is requested one additional TxBD must be set up. The
+         * first TxBD points to the FCB and must have a data length of
+         * GMAC_FCB_LEN. The second TxBD points to the actual frame data with
+         * the full frame length.
+         */
+        if (unlikely(do_tstamp)) {
+                txbdp_tstamp->bufPtr = txbdp_start->bufPtr + GMAC_FCB_LEN;
+                txbdp_tstamp->lstatus |= BD_LFLAG(TXBD_READY) |
+                                (skb_headlen(skb) - GMAC_FCB_LEN);
+                lstatus |= BD_LFLAG(TXBD_CRC | TXBD_READY) | GMAC_FCB_LEN;
+        } else {
+                lstatus |= BD_LFLAG(TXBD_CRC | TXBD_READY) | skb_headlen(skb);
+        }
 
         /*
          * We can work in parallel with gfar_clean_tx_ring(), except
@@ -2110,7 +2163,7 @@ static int gfar_start_xmit(struct sk_buff *skb, struct net_device *dev)
         tx_queue->cur_tx = next_txbd(txbdp, base, tx_queue->tx_ring_size);
 
         /* reduce TxBD free count */
-        tx_queue->num_txbdfree -= (nr_frags + 1);
+        tx_queue->num_txbdfree -= (nr_txbds);
 
         dev->trans_start = jiffies;
 
@@ -2301,16 +2354,18 @@ static int gfar_clean_tx_ring(struct gfar_priv_tx_q *tx_queue)
         struct net_device *dev = tx_queue->dev;
         struct gfar_private *priv = netdev_priv(dev);
         struct gfar_priv_rx_q *rx_queue = NULL;
-        struct txbd8 *bdp;
+        struct txbd8 *bdp, *next = NULL;
         struct txbd8 *lbdp = NULL;
         struct txbd8 *base = tx_queue->tx_bd_base;
         struct sk_buff *skb;
         int skb_dirtytx;
         int tx_ring_size = tx_queue->tx_ring_size;
-        int frags = 0;
+        int frags = 0, nr_txbds = 0;
         int i;
         int howmany = 0;
         u32 lstatus;
+        size_t buflen;
+        union skb_shared_tx *shtx;
 
         rx_queue = priv->rx_queue[tx_queue->qindex];
         bdp = tx_queue->dirty_tx;
@@ -2320,7 +2375,18 @@ static int gfar_clean_tx_ring(struct gfar_priv_tx_q *tx_queue)
                 unsigned long flags;
 
                 frags = skb_shinfo(skb)->nr_frags;
-                lbdp = skip_txbd(bdp, frags, base, tx_ring_size);
+
+                /*
+                 * When time stamping, one additional TxBD must be freed.
+                 * Also, we need to dma_unmap_single() the TxPAL.
+                 */
+                shtx = skb_tx(skb);
+                if (unlikely(shtx->in_progress))
+                        nr_txbds = frags + 2;
+                else
+                        nr_txbds = frags + 1;
+
+                lbdp = skip_txbd(bdp, nr_txbds - 1, base, tx_ring_size);
 
                 lstatus = lbdp->lstatus;
 
@@ -2329,10 +2395,24 @@ static int gfar_clean_tx_ring(struct gfar_priv_tx_q *tx_queue)
                                 (lstatus & BD_LENGTH_MASK))
                         break;
 
-                dma_unmap_single(&priv->ofdev->dev,
-                                bdp->bufPtr,
-                                bdp->length,
-                                DMA_TO_DEVICE);
+                if (unlikely(shtx->in_progress)) {
+                        next = next_txbd(bdp, base, tx_ring_size);
+                        buflen = next->length + GMAC_FCB_LEN;
+                } else
+                        buflen = bdp->length;
+
+                dma_unmap_single(&priv->ofdev->dev, bdp->bufPtr,
+                                buflen, DMA_TO_DEVICE);
+
+                if (unlikely(shtx->in_progress)) {
+                        struct skb_shared_hwtstamps shhwtstamps;
+                        u64 *ns = (u64*) (((u32)skb->data + 0x10) & ~0x7);
+                        memset(&shhwtstamps, 0, sizeof(shhwtstamps));
+                        shhwtstamps.hwtstamp = ns_to_ktime(*ns);
+                        skb_tstamp_tx(skb, &shhwtstamps);
+                        bdp->lstatus &= BD_LFLAG(TXBD_WRAP);
+                        bdp = next;
+                }
 
                 bdp->lstatus &= BD_LFLAG(TXBD_WRAP);
                 bdp = next_txbd(bdp, base, tx_ring_size);
@@ -2364,7 +2444,7 @@ static int gfar_clean_tx_ring(struct gfar_priv_tx_q *tx_queue)
 
                 howmany++;
                 spin_lock_irqsave(&tx_queue->txlock, flags);
-                tx_queue->num_txbdfree += frags + 1;
+                tx_queue->num_txbdfree += nr_txbds;
                 spin_unlock_irqrestore(&tx_queue->txlock, flags);
         }
 
diff --git a/drivers/net/gianfar.h b/drivers/net/gianfar.h
index 1ea287cba231..ac4a92e08c09 100644
--- a/drivers/net/gianfar.h
+++ b/drivers/net/gianfar.h
@@ -540,7 +540,7 @@ struct txbd8
 
 struct txfcb {
         u8      flags;
-        u8      reserved;
+        u8      ptp;    /* Flag to enable tx timestamping */
         u8      l4os;   /* Level 4 Header Offset */
         u8      l3os;   /* Level 3 Header Offset */
         u16     phcs;   /* Pseudo-header Checksum */
@@ -1105,6 +1105,7 @@ struct gfar_private {
 
         /* HW time stamping enabled flag */
         int hwts_rx_en;
+        int hwts_tx_en;
 };
 
 extern unsigned int ftp_rqfpr[MAX_FILER_IDX + 1];