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 82c4d6c..478b025 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);