caif-hsi: robust frame aggregation for HSI

Implement aggregation algorithm, combining more data into a single
HSI transfer. 4 different traffic categories are supported:
 1. TC_PRIO_CONTROL .. TC_PRIO_MAX (CTL)
 2. TC_PRIO_INTERACTIVE            (VO)
 3. TC_PRIO_INTERACTIVE_BULK       (VI)
 4. TC_PRIO_BESTEFFORT, TC_PRIO_BULK, TC_PRIO_FILLER (BEBK)

Signed-off-by: Dmitry Tarnyagin <dmitry.tarnyagin@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 188 insertions, 55 deletions

diff --git a/drivers/net/caif/caif_hsi.c b/drivers/net/caif/caif_hsi.c
index 9c1c8cd5223f..9849a238d54a 100644
--- a/drivers/net/caif/caif_hsi.c
+++ b/drivers/net/caif/caif_hsi.c
@@ -19,6 +19,7 @@
 #include <linux/if_arp.h>
 #include <linux/timer.h>
 #include <linux/rtnetlink.h>
+#include <linux/pkt_sched.h>
 #include <net/caif/caif_layer.h>
 #include <net/caif/caif_hsi.h>
 
@@ -34,6 +35,10 @@ static int inactivity_timeout = 1000;
 module_param(inactivity_timeout, int, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(inactivity_timeout, "Inactivity timeout on HSI, ms.");
 
+static int aggregation_timeout = 1;
+module_param(aggregation_timeout, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(aggregation_timeout, "Aggregation timeout on HSI, ms.");
+
 /*
  * HSI padding options.
  * Warning: must be a base of 2 (& operation used) and can not be zero !
@@ -86,24 +91,84 @@ static void cfhsi_inactivity_tout(unsigned long arg)
                 queue_work(cfhsi->wq, &cfhsi->wake_down_work);
 }
 
+static void cfhsi_update_aggregation_stats(struct cfhsi *cfhsi,
+                                           const struct sk_buff *skb,
+                                           int direction)
+{
+        struct caif_payload_info *info;
+        int hpad, tpad, len;
+
+        info = (struct caif_payload_info *)&skb->cb;
+        hpad = 1 + PAD_POW2((info->hdr_len + 1), hsi_head_align);
+        tpad = PAD_POW2((skb->len + hpad), hsi_tail_align);
+        len = skb->len + hpad + tpad;
+
+        if (direction > 0)
+                cfhsi->aggregation_len += len;
+        else if (direction < 0)
+                cfhsi->aggregation_len -= len;
+}
+
+static bool cfhsi_can_send_aggregate(struct cfhsi *cfhsi)
+{
+        int i;
+
+        if (cfhsi->aggregation_timeout < 0)
+                return true;
+
+        for (i = 0; i < CFHSI_PRIO_BEBK; ++i) {
+                if (cfhsi->qhead[i].qlen)
+                        return true;
+        }
+
+        /* TODO: Use aggregation_len instead */
+        if (cfhsi->qhead[CFHSI_PRIO_BEBK].qlen >= CFHSI_MAX_PKTS)
+                return true;
+
+        return false;
+}
+
+static struct sk_buff *cfhsi_dequeue(struct cfhsi *cfhsi)
+{
+        struct sk_buff *skb;
+        int i;
+
+        for (i = 0; i < CFHSI_PRIO_LAST; ++i) {
+                skb = skb_dequeue(&cfhsi->qhead[i]);
+                if (skb)
+                        break;
+        }
+
+        return skb;
+}
+
+static int cfhsi_tx_queue_len(struct cfhsi *cfhsi)
+{
+        int i, len = 0;
+        for (i = 0; i < CFHSI_PRIO_LAST; ++i)
+                len += skb_queue_len(&cfhsi->qhead[i]);
+        return len;
+}
+
 static void cfhsi_abort_tx(struct cfhsi *cfhsi)
 {
         struct sk_buff *skb;
 
         for (;;) {
                 spin_lock_bh(&cfhsi->lock);
-                skb = skb_dequeue(&cfhsi->qhead);
+                skb = cfhsi_dequeue(cfhsi);
                 if (!skb)
                         break;
 
                 cfhsi->ndev->stats.tx_errors++;
                 cfhsi->ndev->stats.tx_dropped++;
+                cfhsi_update_aggregation_stats(cfhsi, skb, -1);
                 spin_unlock_bh(&cfhsi->lock);
                 kfree_skb(skb);
         }
         cfhsi->tx_state = CFHSI_TX_STATE_IDLE;
         if (!test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
-                mod_timer(&cfhsi->timer,
+                mod_timer(&cfhsi->inactivity_timer,
                         jiffies + cfhsi->inactivity_timeout);
         spin_unlock_bh(&cfhsi->lock);
 }
@@ -169,7 +234,7 @@ static int cfhsi_tx_frm(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
         struct sk_buff *skb;
         u8 *pfrm = desc->emb_frm + CFHSI_MAX_EMB_FRM_SZ;
 
-        skb = skb_dequeue(&cfhsi->qhead);
+        skb = cfhsi_dequeue(cfhsi);
         if (!skb)
                 return 0;
 
@@ -196,11 +261,16 @@ static int cfhsi_tx_frm(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
                         pemb += hpad;
 
                         /* Update network statistics. */
+                        spin_lock_bh(&cfhsi->lock);
                         cfhsi->ndev->stats.tx_packets++;
                         cfhsi->ndev->stats.tx_bytes += skb->len;
+                        cfhsi_update_aggregation_stats(cfhsi, skb, -1);
+                        spin_unlock_bh(&cfhsi->lock);
 
                         /* Copy in embedded CAIF frame. */
                         skb_copy_bits(skb, 0, pemb, skb->len);
+
+                        /* Consume the SKB */
                         consume_skb(skb);
                         skb = NULL;
                 }
@@ -214,7 +284,7 @@ static int cfhsi_tx_frm(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
                 int tpad = 0;
 
                 if (!skb)
-                        skb = skb_dequeue(&cfhsi->qhead);
+                        skb = cfhsi_dequeue(cfhsi);
 
                 if (!skb)
                         break;
@@ -233,8 +303,11 @@ static int cfhsi_tx_frm(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
                 pfrm += hpad;
 
                 /* Update network statistics. */
+                spin_lock_bh(&cfhsi->lock);
                 cfhsi->ndev->stats.tx_packets++;
                 cfhsi->ndev->stats.tx_bytes += skb->len;
+                cfhsi_update_aggregation_stats(cfhsi, skb, -1);
+                spin_unlock_bh(&cfhsi->lock);
 
                 /* Copy in CAIF frame. */
                 skb_copy_bits(skb, 0, pfrm, skb->len);
@@ -244,6 +317,8 @@ static int cfhsi_tx_frm(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
 
                 /* Update frame pointer. */
                 pfrm += skb->len + tpad;
+
+                /* Consume the SKB */
                 consume_skb(skb);
                 skb = NULL;
 
@@ -258,8 +333,7 @@ static int cfhsi_tx_frm(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
         }
 
         /* Check if we can piggy-back another descriptor. */
-        skb = skb_peek(&cfhsi->qhead);
-        if (skb)
+        if (cfhsi_can_send_aggregate(cfhsi))
                 desc->header |= CFHSI_PIGGY_DESC;
         else
                 desc->header &= ~CFHSI_PIGGY_DESC;
@@ -267,61 +341,71 @@ static int cfhsi_tx_frm(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
         return CFHSI_DESC_SZ + pld_len;
 }
 
-static void cfhsi_tx_done(struct cfhsi *cfhsi)
+static void cfhsi_start_tx(struct cfhsi *cfhsi)
 {
-        struct cfhsi_desc *desc = NULL;
-        int len = 0;
-        int res;
+        struct cfhsi_desc *desc = (struct cfhsi_desc *)cfhsi->tx_buf;
+        int len, res;
 
         dev_dbg(&cfhsi->ndev->dev, "%s.\n", __func__);
 
         if (test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
                 return;
 
-        desc = (struct cfhsi_desc *)cfhsi->tx_buf;
-
         do {
-                /*
-                 * Send flow on if flow off has been previously signalled
-                 * and number of packets is below low water mark.
-                 */
-                spin_lock_bh(&cfhsi->lock);
-                if (cfhsi->flow_off_sent &&
-                                cfhsi->qhead.qlen <= cfhsi->q_low_mark &&
-                                cfhsi->cfdev.flowctrl) {
-
-                        cfhsi->flow_off_sent = 0;
-                        cfhsi->cfdev.flowctrl(cfhsi->ndev, ON);
-                }
-                spin_unlock_bh(&cfhsi->lock);
-
                 /* Create HSI frame. */
-                do {
-                        len = cfhsi_tx_frm(desc, cfhsi);
-                        if (!len) {
-                                spin_lock_bh(&cfhsi->lock);
-                                if (unlikely(skb_peek(&cfhsi->qhead))) {
-                                        spin_unlock_bh(&cfhsi->lock);
-                                        continue;
-                                }
-                                cfhsi->tx_state = CFHSI_TX_STATE_IDLE;
-                                /* Start inactivity timer. */
-                                mod_timer(&cfhsi->timer,
-                                        jiffies + cfhsi->inactivity_timeout);
+                len = cfhsi_tx_frm(desc, cfhsi);
+                if (!len) {
+                        spin_lock_bh(&cfhsi->lock);
+                        if (unlikely(cfhsi_tx_queue_len(cfhsi))) {
                                 spin_unlock_bh(&cfhsi->lock);
-                                goto done;
+                                res = -EAGAIN;
+                                continue;
                         }
-                } while (!len);
+                        cfhsi->tx_state = CFHSI_TX_STATE_IDLE;
+                        /* Start inactivity timer. */
+                        mod_timer(&cfhsi->inactivity_timer,
+                                jiffies + cfhsi->inactivity_timeout);
+                        spin_unlock_bh(&cfhsi->lock);
+                        break;
+                }
 
                 /* Set up new transfer. */
                 res = cfhsi->dev->cfhsi_tx(cfhsi->tx_buf, len, cfhsi->dev);
-                if (WARN_ON(res < 0)) {
+                if (WARN_ON(res < 0))
                         dev_err(&cfhsi->ndev->dev, "%s: TX error %d.\n",
                                 __func__, res);
-                }
         } while (res < 0);
+}
+
+static void cfhsi_tx_done(struct cfhsi *cfhsi)
+{
+        dev_dbg(&cfhsi->ndev->dev, "%s.\n", __func__);
+
+        if (test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
+                return;
+
+        /*
+         * Send flow on if flow off has been previously signalled
+         * and number of packets is below low water mark.
+         */
+        spin_lock_bh(&cfhsi->lock);
+        if (cfhsi->flow_off_sent &&
+                        cfhsi_tx_queue_len(cfhsi) <= cfhsi->q_low_mark &&
+                        cfhsi->cfdev.flowctrl) {
+
+                cfhsi->flow_off_sent = 0;
+                cfhsi->cfdev.flowctrl(cfhsi->ndev, ON);
+        }
+
+        if (cfhsi_can_send_aggregate(cfhsi)) {
+                spin_unlock_bh(&cfhsi->lock);
+                cfhsi_start_tx(cfhsi);
+        } else {
+                mod_timer(&cfhsi->aggregation_timer,
+                        jiffies + cfhsi->aggregation_timeout);
+                spin_unlock_bh(&cfhsi->lock);
+        }
 
-done:
         return;
 }
 
@@ -560,7 +644,7 @@ static void cfhsi_rx_done(struct cfhsi *cfhsi)
 
         /* Update inactivity timer if pending. */
         spin_lock_bh(&cfhsi->lock);
-        mod_timer_pending(&cfhsi->timer,
+        mod_timer_pending(&cfhsi->inactivity_timer,
                         jiffies + cfhsi->inactivity_timeout);
         spin_unlock_bh(&cfhsi->lock);
 
@@ -793,12 +877,12 @@ wake_ack:
 
         spin_lock_bh(&cfhsi->lock);
 
-        /* Resume transmit if queue is not empty. */
-        if (!skb_peek(&cfhsi->qhead)) {
+        /* Resume transmit if queues are not empty. */
+        if (!cfhsi_tx_queue_len(cfhsi)) {
                 dev_dbg(&cfhsi->ndev->dev, "%s: Peer wake, start timer.\n",
                         __func__);
                 /* Start inactivity timer. */
-                mod_timer(&cfhsi->timer,
+                mod_timer(&cfhsi->inactivity_timer,
                                 jiffies + cfhsi->inactivity_timeout);
                 spin_unlock_bh(&cfhsi->lock);
                 return;
@@ -934,20 +1018,53 @@ static void cfhsi_wake_down_cb(struct cfhsi_drv *drv)
         wake_up_interruptible(&cfhsi->wake_down_wait);
 }
 
+static void cfhsi_aggregation_tout(unsigned long arg)
+{
+        struct cfhsi *cfhsi = (struct cfhsi *)arg;
+
+        dev_dbg(&cfhsi->ndev->dev, "%s.\n",
+                __func__);
+
+        cfhsi_start_tx(cfhsi);
+}
+
 static int cfhsi_xmit(struct sk_buff *skb, struct net_device *dev)
 {
         struct cfhsi *cfhsi = NULL;
         int start_xfer = 0;
         int timer_active;
+        int prio;
 
         if (!dev)
                 return -EINVAL;
 
         cfhsi = netdev_priv(dev);
 
+        switch (skb->priority) {
+        case TC_PRIO_BESTEFFORT:
+        case TC_PRIO_FILLER:
+        case TC_PRIO_BULK:
+                prio = CFHSI_PRIO_BEBK;
+                break;
+        case TC_PRIO_INTERACTIVE_BULK:
+                prio = CFHSI_PRIO_VI;
+                break;
+        case TC_PRIO_INTERACTIVE:
+                prio = CFHSI_PRIO_VO;
+                break;
+        case TC_PRIO_CONTROL:
+        default:
+                prio = CFHSI_PRIO_CTL;
+                break;
+        }
+
         spin_lock_bh(&cfhsi->lock);
 
-        skb_queue_tail(&cfhsi->qhead, skb);
+        /* Update aggregation statistics  */
+        cfhsi_update_aggregation_stats(cfhsi, skb, 1);
+
+        /* Queue the SKB */
+        skb_queue_tail(&cfhsi->qhead[prio], skb);
 
         /* Sanity check; xmit should not be called after unregister_netdev */
         if (WARN_ON(test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))) {
@@ -958,7 +1075,7 @@ static int cfhsi_xmit(struct sk_buff *skb, struct net_device *dev)
 
         /* Send flow off if number of packets is above high water mark. */
         if (!cfhsi->flow_off_sent &&
-                cfhsi->qhead.qlen > cfhsi->q_high_mark &&
+                cfhsi_tx_queue_len(cfhsi) > cfhsi->q_high_mark &&
                 cfhsi->cfdev.flowctrl) {
                 cfhsi->flow_off_sent = 1;
                 cfhsi->cfdev.flowctrl(cfhsi->ndev, OFF);
@@ -970,12 +1087,18 @@ static int cfhsi_xmit(struct sk_buff *skb, struct net_device *dev)
         }
 
         if (!start_xfer) {
+                /* Send aggregate if it is possible */
+                bool aggregate_ready =
+                        cfhsi_can_send_aggregate(cfhsi) &&
+                        del_timer(&cfhsi->aggregation_timer) > 0;
                 spin_unlock_bh(&cfhsi->lock);
+                if (aggregate_ready)
+                        cfhsi_start_tx(cfhsi);
                 return 0;
         }
 
         /* Delete inactivity timer if started. */
-        timer_active = del_timer_sync(&cfhsi->timer);
+        timer_active = del_timer_sync(&cfhsi->inactivity_timer);
 
         spin_unlock_bh(&cfhsi->lock);
 
@@ -1026,6 +1149,7 @@ static const struct net_device_ops cfhsi_ops = {
 
 static void cfhsi_setup(struct net_device *dev)
 {
+        int i;
         struct cfhsi *cfhsi = netdev_priv(dev);
         dev->features = 0;
         dev->netdev_ops = &cfhsi_ops;
@@ -1034,7 +1158,8 @@ static void cfhsi_setup(struct net_device *dev)
         dev->mtu = CFHSI_MAX_CAIF_FRAME_SZ;
         dev->tx_queue_len = 0;
         dev->destructor = free_netdev;
-        skb_queue_head_init(&cfhsi->qhead);
+        for (i = 0; i < CFHSI_PRIO_LAST; ++i)
+                skb_queue_head_init(&cfhsi->qhead[i]);
         cfhsi->cfdev.link_select = CAIF_LINK_HIGH_BANDW;
         cfhsi->cfdev.use_frag = false;
         cfhsi->cfdev.use_stx = false;
@@ -1111,6 +1236,9 @@ int cfhsi_probe(struct platform_device *pdev)
                 cfhsi->inactivity_timeout = NEXT_TIMER_MAX_DELTA;
         }
 
+        /* Initialize aggregation timeout */
+        cfhsi->aggregation_timeout = aggregation_timeout;
+
         /* Initialize recieve vaiables. */
         cfhsi->rx_ptr = cfhsi->rx_buf;
         cfhsi->rx_len = CFHSI_DESC_SZ;
@@ -1150,13 +1278,17 @@ int cfhsi_probe(struct platform_device *pdev)
         init_waitqueue_head(&cfhsi->flush_fifo_wait);
 
         /* Setup the inactivity timer. */
-        init_timer(&cfhsi->timer);
-        cfhsi->timer.data = (unsigned long)cfhsi;
-        cfhsi->timer.function = cfhsi_inactivity_tout;
+        init_timer(&cfhsi->inactivity_timer);
+        cfhsi->inactivity_timer.data = (unsigned long)cfhsi;
+        cfhsi->inactivity_timer.function = cfhsi_inactivity_tout;
         /* Setup the slowpath RX timer. */
         init_timer(&cfhsi->rx_slowpath_timer);
         cfhsi->rx_slowpath_timer.data = (unsigned long)cfhsi;
         cfhsi->rx_slowpath_timer.function = cfhsi_rx_slowpath;
+        /* Setup the aggregation timer. */
+        init_timer(&cfhsi->aggregation_timer);
+        cfhsi->aggregation_timer.data = (unsigned long)cfhsi;
+        cfhsi->aggregation_timer.function = cfhsi_aggregation_tout;
 
         /* Add CAIF HSI device to list. */
         spin_lock(&cfhsi_list_lock);
@@ -1222,8 +1354,9 @@ static void cfhsi_shutdown(struct cfhsi *cfhsi)
         flush_workqueue(cfhsi->wq);
 
         /* Delete timers if pending */
-        del_timer_sync(&cfhsi->timer);
+        del_timer_sync(&cfhsi->inactivity_timer);
         del_timer_sync(&cfhsi->rx_slowpath_timer);
+        del_timer_sync(&cfhsi->aggregation_timer);
 
         /* Cancel pending RX request (if any) */
         cfhsi->dev->cfhsi_rx_cancel(cfhsi->dev);