caif-hsi: Making read and writes asynchronous.

Some platforms do not allow to put HSI block into low-power
mode when FIFO is not empty. The patch flushes (by reading)
FIFO at wake down sequence. Asynchronous read and write is
implemented for that. As a side effect this will also greatly
improve performance.

Signed-off-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 127 insertions, 136 deletions

diff --git a/drivers/net/caif/caif_hsi.c b/drivers/net/caif/caif_hsi.c
index 82c4d6ca2d3f..478b025c9f8b 100644
--- a/drivers/net/caif/caif_hsi.c
+++ b/drivers/net/caif/caif_hsi.c
@@ -145,7 +145,7 @@ static int cfhsi_flush_fifo(struct cfhsi *cfhsi)
                 }
 
                 ret = 5 * HZ;
-                wait_event_interruptible_timeout(cfhsi->flush_fifo_wait,
+                ret = wait_event_interruptible_timeout(cfhsi->flush_fifo_wait,
                          !test_bit(CFHSI_FLUSH_FIFO, &cfhsi->bits), ret);
 
                 if (ret < 0) {
@@ -272,16 +272,13 @@ static int cfhsi_tx_frm(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
         return CFHSI_DESC_SZ + pld_len;
 }
 
-static void cfhsi_tx_done_work(struct work_struct *work)
+static void cfhsi_tx_done(struct cfhsi *cfhsi)
 {
-        struct cfhsi *cfhsi = NULL;
         struct cfhsi_desc *desc = NULL;
         int len = 0;
         int res;
 
-        cfhsi = container_of(work, struct cfhsi, tx_done_work);
-        dev_dbg(&cfhsi->ndev->dev, "%s.\n",
-                __func__);
+        dev_dbg(&cfhsi->ndev->dev, "%s.\n", __func__);
 
         if (test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
                 return;
@@ -343,11 +340,11 @@ static void cfhsi_tx_done_cb(struct cfhsi_drv *drv)
 
         if (test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
                 return;
-
-        queue_work(cfhsi->wq, &cfhsi->tx_done_work);
+        cfhsi_tx_done(cfhsi);
 }
 
-static int cfhsi_rx_desc(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
+static int cfhsi_rx_desc(struct cfhsi_desc *desc, struct cfhsi *cfhsi,
+                                bool *dump)
 {
         int xfer_sz = 0;
         int nfrms = 0;
@@ -358,6 +355,7 @@ static int cfhsi_rx_desc(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
                         (desc->offset > CFHSI_MAX_EMB_FRM_SZ)) {
                 dev_err(&cfhsi->ndev->dev, "%s: Invalid descriptor.\n",
                         __func__);
+                *dump = true;
                 return 0;
         }
 
@@ -365,7 +363,7 @@ static int cfhsi_rx_desc(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
         if (desc->offset) {
                 struct sk_buff *skb;
                 u8 *dst = NULL;
-                int len = 0, retries = 0;
+                int len = 0;
                 pfrm = ((u8 *)desc) + desc->offset;
 
                 /* Remove offset padding. */
@@ -378,24 +376,11 @@ static int cfhsi_rx_desc(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
 
 
                 /* Allocate SKB (OK even in IRQ context). */
-                skb = alloc_skb(len + 1, GFP_KERNEL);
-                while (!skb) {
-                        retries++;
-                        schedule_timeout(1);
-                        skb = alloc_skb(len + 1, GFP_KERNEL);
-                        if (skb) {
-                                printk(KERN_WARNING "%s: slept for %u "
-                                                "before getting memory\n",
-                                                __func__, retries);
-                                break;
-                        }
-                        if (retries > HZ) {
-                                printk(KERN_ERR "%s: slept for 1HZ and "
-                                                "did not get memory\n",
-                                                __func__);
-                                cfhsi->ndev->stats.rx_dropped++;
-                                goto drop_frame;
-                        }
+                skb = alloc_skb(len + 1, GFP_ATOMIC);
+                if (!skb) {
+                        dev_err(&cfhsi->ndev->dev, "%s: Out of memory !\n",
+                                __func__);
+                        return -ENOMEM;
                 }
                 caif_assert(skb != NULL);
 
@@ -421,7 +406,6 @@ static int cfhsi_rx_desc(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
                 cfhsi->ndev->stats.rx_bytes += len;
         }
 
-drop_frame:
         /* Calculate transfer length. */
         plen = desc->cffrm_len;
         while (nfrms < CFHSI_MAX_PKTS && *plen) {
@@ -439,12 +423,13 @@ drop_frame:
                                 "%s: Invalid payload len: %d, ignored.\n",
                         __func__, xfer_sz);
                 xfer_sz = 0;
+                *dump = true;
         }
-
         return xfer_sz;
 }
 
-static int cfhsi_rx_pld(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
+static int cfhsi_rx_pld(struct cfhsi_desc *desc, struct cfhsi *cfhsi,
+                                bool *dump)
 {
         int rx_sz = 0;
         int nfrms = 0;
@@ -456,21 +441,33 @@ static int cfhsi_rx_pld(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
                         (desc->offset > CFHSI_MAX_EMB_FRM_SZ))) {
                 dev_err(&cfhsi->ndev->dev, "%s: Invalid descriptor.\n",
                         __func__);
+                *dump = true;
                 return -EINVAL;
         }
 
         /* Set frame pointer to start of payload. */
         pfrm = desc->emb_frm + CFHSI_MAX_EMB_FRM_SZ;
         plen = desc->cffrm_len;
+
+        /* Skip already processed frames. */
+        while (nfrms < cfhsi->rx_state.nfrms) {
+                pfrm += *plen;
+                rx_sz += *plen;
+                plen++;
+                nfrms++;
+        }
+
+        /* Parse payload. */
         while (nfrms < CFHSI_MAX_PKTS && *plen) {
                 struct sk_buff *skb;
                 u8 *dst = NULL;
                 u8 *pcffrm = NULL;
-                int len = 0, retries = 0;
+                int len = 0;
 
                 if (WARN_ON(desc->cffrm_len[nfrms] > CFHSI_MAX_PAYLOAD_SZ)) {
                         dev_err(&cfhsi->ndev->dev, "%s: Invalid payload.\n",
                                 __func__);
+                        *dump = true;
                         return -EINVAL;
                 }
 
@@ -483,24 +480,12 @@ static int cfhsi_rx_pld(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
                 len += 2;       /* Add FCS fields. */
 
                 /* Allocate SKB (OK even in IRQ context). */
-                skb = alloc_skb(len + 1, GFP_KERNEL);
-                while (!skb) {
-                        retries++;
-                        schedule_timeout(1);
-                        skb = alloc_skb(len + 1, GFP_KERNEL);
-                        if (skb) {
-                                printk(KERN_WARNING "%s: slept for %u "
-                                                "before getting memory\n",
-                                                __func__, retries);
-                                break;
-                        }
-                        if (retries > HZ) {
-                                printk(KERN_ERR "%s: slept for 1HZ "
-                                                "and did not get memory\n",
-                                                __func__);
-                                cfhsi->ndev->stats.rx_dropped++;
-                                goto drop_frame;
-                        }
+                skb = alloc_skb(len + 1, GFP_ATOMIC);
+                if (!skb) {
+                        dev_err(&cfhsi->ndev->dev, "%s: Out of memory !\n",
+                                __func__);
+                        cfhsi->rx_state.nfrms = nfrms;
+                        return -ENOMEM;
                 }
                 caif_assert(skb != NULL);
 
@@ -524,7 +509,6 @@ static int cfhsi_rx_pld(struct cfhsi_desc *desc, struct cfhsi *cfhsi)
                 cfhsi->ndev->stats.rx_packets++;
                 cfhsi->ndev->stats.rx_bytes += len;
 
-drop_frame:
                 pfrm += *plen;
                 rx_sz += *plen;
                 plen++;
@@ -534,18 +518,16 @@ drop_frame:
         return rx_sz;
 }
 
-static void cfhsi_rx_done_work(struct work_struct *work)
+static void cfhsi_rx_done(struct cfhsi *cfhsi)
 {
         int res;
         int desc_pld_len = 0;
-        struct cfhsi *cfhsi = NULL;
         struct cfhsi_desc *desc = NULL;
+        bool dump = false;
 
-        cfhsi = container_of(work, struct cfhsi, rx_done_work);
         desc = (struct cfhsi_desc *)cfhsi->rx_buf;
 
-        dev_dbg(&cfhsi->ndev->dev, "%s: Kick timer if pending.\n",
-                __func__);
+        dev_dbg(&cfhsi->ndev->dev, "%s\n", __func__);
 
         if (test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
                 return;
@@ -555,21 +537,33 @@ static void cfhsi_rx_done_work(struct work_struct *work)
         mod_timer_pending(&cfhsi->timer, jiffies + CFHSI_INACTIVITY_TOUT);
         spin_unlock_bh(&cfhsi->lock);
 
-        if (cfhsi->rx_state == CFHSI_RX_STATE_DESC) {
-                desc_pld_len = cfhsi_rx_desc(desc, cfhsi);
+        if (cfhsi->rx_state.state == CFHSI_RX_STATE_DESC) {
+                desc_pld_len = cfhsi_rx_desc(desc, cfhsi, &dump);
+                if (desc_pld_len == -ENOMEM)
+                        goto restart;
         } else {
                 int pld_len;
 
-                pld_len = cfhsi_rx_pld(desc, cfhsi);
+                if (!cfhsi->rx_state.piggy_desc) {
+                        pld_len = cfhsi_rx_pld(desc, cfhsi, &dump);
+                        if (pld_len == -ENOMEM)
+                                goto restart;
+                        cfhsi->rx_state.pld_len = pld_len;
+                } else {
+                        pld_len = cfhsi->rx_state.pld_len;
+                }
 
                 if ((pld_len > 0) && (desc->header & CFHSI_PIGGY_DESC)) {
                         struct cfhsi_desc *piggy_desc;
                         piggy_desc = (struct cfhsi_desc *)
                                 (desc->emb_frm + CFHSI_MAX_EMB_FRM_SZ +
                                                 pld_len);
+                        cfhsi->rx_state.piggy_desc = true;
 
                         /* Extract piggy-backed descriptor. */
-                        desc_pld_len = cfhsi_rx_desc(piggy_desc, cfhsi);
+                        desc_pld_len = cfhsi_rx_desc(piggy_desc, cfhsi, &dump);
+                        if (desc_pld_len == -ENOMEM)
+                                goto restart;
 
                         /*
                          * Copy needed information from the piggy-backed
@@ -580,16 +574,24 @@ static void cfhsi_rx_done_work(struct work_struct *work)
                 }
         }
 
+        if (unlikely(dump)) {
+                size_t rx_offset = cfhsi->rx_ptr - cfhsi->rx_buf;
+                dev_err(&cfhsi->ndev->dev, "%s: RX offset: %u.\n",
+                        __func__, (unsigned) rx_offset);
+                print_hex_dump_bytes("--> ", DUMP_PREFIX_NONE,
+                                cfhsi->rx_buf, cfhsi->rx_len + rx_offset);
+        }
+
+        memset(&cfhsi->rx_state, 0, sizeof(cfhsi->rx_state));
         if (desc_pld_len) {
-                cfhsi->rx_state = CFHSI_RX_STATE_PAYLOAD;
+                cfhsi->rx_state.state = CFHSI_RX_STATE_PAYLOAD;
                 cfhsi->rx_ptr = cfhsi->rx_buf + CFHSI_DESC_SZ;
                 cfhsi->rx_len = desc_pld_len;
         } else {
-                cfhsi->rx_state = CFHSI_RX_STATE_DESC;
+                cfhsi->rx_state.state = CFHSI_RX_STATE_DESC;
                 cfhsi->rx_ptr = cfhsi->rx_buf;
                 cfhsi->rx_len = CFHSI_DESC_SZ;
         }
-        clear_bit(CFHSI_PENDING_RX, &cfhsi->bits);
 
         if (test_bit(CFHSI_AWAKE, &cfhsi->bits)) {
                 /* Set up new transfer. */
@@ -604,6 +606,26 @@ static void cfhsi_rx_done_work(struct work_struct *work)
                         cfhsi->ndev->stats.rx_dropped++;
                 }
         }
+        return;
+
+restart:
+        if (++cfhsi->rx_state.retries > CFHSI_MAX_RX_RETRIES) {
+                dev_err(&cfhsi->ndev->dev, "%s: No memory available "
+                        "in %d iterations.\n",
+                        __func__, CFHSI_MAX_RX_RETRIES);
+                BUG();
+        }
+        mod_timer(&cfhsi->rx_slowpath_timer, jiffies + 1);
+}
+
+static void cfhsi_rx_slowpath(unsigned long arg)
+{
+        struct cfhsi *cfhsi = (struct cfhsi *)arg;
+
+        dev_dbg(&cfhsi->ndev->dev, "%s.\n",
+                __func__);
+
+        cfhsi_rx_done(cfhsi);
 }
 
 static void cfhsi_rx_done_cb(struct cfhsi_drv *drv)
@@ -617,12 +639,10 @@ static void cfhsi_rx_done_cb(struct cfhsi_drv *drv)
         if (test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
                 return;
 
-        set_bit(CFHSI_PENDING_RX, &cfhsi->bits);
-
         if (test_and_clear_bit(CFHSI_FLUSH_FIFO, &cfhsi->bits))
                 wake_up_interruptible(&cfhsi->flush_fifo_wait);
         else
-                queue_work(cfhsi->wq, &cfhsi->rx_done_work);
+                cfhsi_rx_done(cfhsi);
 }
 
 static void cfhsi_wake_up(struct work_struct *work)
@@ -651,9 +671,9 @@ static void cfhsi_wake_up(struct work_struct *work)
                 __func__);
 
         /* Wait for acknowledge. */
-        ret = CFHSI_WAKEUP_TOUT;
-        wait_event_interruptible_timeout(cfhsi->wake_up_wait,
-                                        test_bit(CFHSI_WAKE_UP_ACK,
+        ret = CFHSI_WAKE_TOUT;
+        ret = wait_event_interruptible_timeout(cfhsi->wake_up_wait,
+                                        test_and_clear_bit(CFHSI_WAKE_UP_ACK,
                                                         &cfhsi->bits), ret);
         if (unlikely(ret < 0)) {
                 /* Interrupted by signal. */
@@ -678,16 +698,11 @@ static void cfhsi_wake_up(struct work_struct *work)
         clear_bit(CFHSI_WAKE_UP, &cfhsi->bits);
 
         /* Resume read operation. */
-        if (!test_bit(CFHSI_PENDING_RX, &cfhsi->bits)) {
-                dev_dbg(&cfhsi->ndev->dev, "%s: Start RX.\n",
-                        __func__);
-                res = cfhsi->dev->cfhsi_rx(cfhsi->rx_ptr,
-                                cfhsi->rx_len, cfhsi->dev);
-                if (WARN_ON(res < 0)) {
-                        dev_err(&cfhsi->ndev->dev, "%s: RX error %d.\n",
-                                __func__, res);
-                }
-        }
+        dev_dbg(&cfhsi->ndev->dev, "%s: Start RX.\n", __func__);
+        res = cfhsi->dev->cfhsi_rx(cfhsi->rx_ptr, cfhsi->rx_len, cfhsi->dev);
+
+        if (WARN_ON(res < 0))
+                dev_err(&cfhsi->ndev->dev, "%s: RX err %d.\n", __func__, res);
 
         /* Clear power up acknowledment. */
         clear_bit(CFHSI_WAKE_UP_ACK, &cfhsi->bits);
@@ -726,50 +741,29 @@ static void cfhsi_wake_up(struct work_struct *work)
                                 "%s: Failed to create HSI frame: %d.\n",
                                 __func__, len);
         }
-
 }
 
 static void cfhsi_wake_down(struct work_struct *work)
 {
         long ret;
         struct cfhsi *cfhsi = NULL;
-        size_t fifo_occupancy;
+        size_t fifo_occupancy = 0;
+        int retry = CFHSI_WAKE_TOUT;
 
         cfhsi = container_of(work, struct cfhsi, wake_down_work);
-        dev_dbg(&cfhsi->ndev->dev, "%s.\n",
-                __func__);
+        dev_dbg(&cfhsi->ndev->dev, "%s.\n", __func__);
 
         if (test_bit(CFHSI_SHUTDOWN, &cfhsi->bits))
                 return;
 
-        /* Check if there is something in FIFO. */
-        if (WARN_ON(cfhsi->dev->cfhsi_fifo_occupancy(cfhsi->dev,
-                                                        &fifo_occupancy)))
-                fifo_occupancy = 0;
-
-        if (fifo_occupancy) {
-                dev_dbg(&cfhsi->ndev->dev,
-                                "%s: %u words in RX FIFO, restart timer.\n",
-                                __func__, (unsigned) fifo_occupancy);
-                spin_lock_bh(&cfhsi->lock);
-                mod_timer(&cfhsi->timer,
-                                jiffies + CFHSI_INACTIVITY_TOUT);
-                spin_unlock_bh(&cfhsi->lock);
-                return;
-        }
-
-        /* Cancel pending RX requests */
-        cfhsi->dev->cfhsi_rx_cancel(cfhsi->dev);
-
         /* Deactivate wake line. */
         cfhsi->dev->cfhsi_wake_down(cfhsi->dev);
 
         /* Wait for acknowledge. */
-        ret = CFHSI_WAKEUP_TOUT;
+        ret = CFHSI_WAKE_TOUT;
         ret = wait_event_interruptible_timeout(cfhsi->wake_down_wait,
-                                        test_bit(CFHSI_WAKE_DOWN_ACK,
-                                                        &cfhsi->bits),
-                                        ret);
+                                        test_and_clear_bit(CFHSI_WAKE_DOWN_ACK,
+                                                        &cfhsi->bits), ret);
         if (ret < 0) {
                 /* Interrupted by signal. */
                 dev_info(&cfhsi->ndev->dev, "%s: Signalled: %ld.\n",
@@ -777,28 +771,31 @@ static void cfhsi_wake_down(struct work_struct *work)
                 return;
         } else if (!ret) {
                 /* Timeout */
-                dev_err(&cfhsi->ndev->dev, "%s: Timeout.\n",
-                        __func__);
+                dev_err(&cfhsi->ndev->dev, "%s: Timeout.\n", __func__);
         }
 
-        /* Clear power down acknowledment. */
-        clear_bit(CFHSI_WAKE_DOWN_ACK, &cfhsi->bits);
+        /* Check FIFO occupancy. */
+        while (retry) {
+                WARN_ON(cfhsi->dev->cfhsi_fifo_occupancy(cfhsi->dev,
+                                                        &fifo_occupancy));
+
+                if (!fifo_occupancy)
+                        break;
+
+                set_current_state(TASK_INTERRUPTIBLE);
+                schedule_timeout(1);
+                retry--;
+        }
+
+        if (!retry)
+                dev_err(&cfhsi->ndev->dev, "%s: FIFO Timeout.\n", __func__);
+
+        /* Clear AWAKE condition. */
         clear_bit(CFHSI_AWAKE, &cfhsi->bits);
 
-        /* Check if there is something in FIFO. */
-        if (WARN_ON(cfhsi->dev->cfhsi_fifo_occupancy(cfhsi->dev,
-                                                        &fifo_occupancy)))
-                fifo_occupancy = 0;
+        /* Cancel pending RX requests. */
+        cfhsi->dev->cfhsi_rx_cancel(cfhsi->dev);
 
-        if (fifo_occupancy) {
-                dev_dbg(&cfhsi->ndev->dev,
-                                "%s: %u words in RX FIFO, wakeup forced.\n",
-                                __func__, (unsigned) fifo_occupancy);
-                if (!test_and_set_bit(CFHSI_WAKE_UP, &cfhsi->bits))
-                        queue_work(cfhsi->wq, &cfhsi->wake_up_work);
-        } else
-                dev_dbg(&cfhsi->ndev->dev, "%s: Done.\n",
-                        __func__);
 }
 
 static void cfhsi_wake_up_cb(struct cfhsi_drv *drv)
@@ -874,11 +871,7 @@ static int cfhsi_xmit(struct sk_buff *skb, struct net_device *dev)
         }
 
         /* Delete inactivity timer if started. */
-#ifdef CONFIG_SMP
         timer_active = del_timer_sync(&cfhsi->timer);
-#else
-        timer_active = del_timer(&cfhsi->timer);
-#endif /* CONFIG_SMP */
 
         spin_unlock_bh(&cfhsi->lock);
 
@@ -962,7 +955,7 @@ int cfhsi_probe(struct platform_device *pdev)
 
         /* Initialize state vaiables. */
         cfhsi->tx_state = CFHSI_TX_STATE_IDLE;
-        cfhsi->rx_state = CFHSI_RX_STATE_DESC;
+        cfhsi->rx_state.state = CFHSI_RX_STATE_DESC;
 
         /* Set flow info */
         cfhsi->flow_off_sent = 0;
@@ -1012,15 +1005,12 @@ int cfhsi_probe(struct platform_device *pdev)
         /* Initialize the work queues. */
         INIT_WORK(&cfhsi->wake_up_work, cfhsi_wake_up);
         INIT_WORK(&cfhsi->wake_down_work, cfhsi_wake_down);
-        INIT_WORK(&cfhsi->rx_done_work, cfhsi_rx_done_work);
-        INIT_WORK(&cfhsi->tx_done_work, cfhsi_tx_done_work);
 
         /* Clear all bit fields. */
         clear_bit(CFHSI_WAKE_UP_ACK, &cfhsi->bits);
         clear_bit(CFHSI_WAKE_DOWN_ACK, &cfhsi->bits);
         clear_bit(CFHSI_WAKE_UP, &cfhsi->bits);
         clear_bit(CFHSI_AWAKE, &cfhsi->bits);
-        clear_bit(CFHSI_PENDING_RX, &cfhsi->bits);
 
         /* Create work thread. */
         cfhsi->wq = create_singlethread_workqueue(pdev->name);
@@ -1040,6 +1030,10 @@ int cfhsi_probe(struct platform_device *pdev)
         init_timer(&cfhsi->timer);
         cfhsi->timer.data = (unsigned long)cfhsi;
         cfhsi->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;
 
         /* Add CAIF HSI device to list. */
         spin_lock(&cfhsi_list_lock);
@@ -1110,12 +1104,9 @@ static void cfhsi_shutdown(struct cfhsi *cfhsi, bool remove_platform_dev)
         /* Flush workqueue */
         flush_workqueue(cfhsi->wq);
 
-        /* Delete timer if pending */
-#ifdef CONFIG_SMP
+        /* Delete timers if pending */
         del_timer_sync(&cfhsi->timer);
-#else
-        del_timer(&cfhsi->timer);
-#endif /* CONFIG_SMP */
+        del_timer_sync(&cfhsi->rx_slowpath_timer);
 
         /* Cancel pending RX request (if any) */
         cfhsi->dev->cfhsi_rx_cancel(cfhsi->dev);