ntb: add DMA error handling for TX DMA

Adding support on the tx DMA path to allow recovery of errors when
DMA responds with error status and abort all the subsequent ops.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Acked-by: Allen Hubbe <Allen.Hubbe@emc.com>
Cc: Jon Mason <jdmason@kudzu.us>
Cc: linux-ntb@googlegroups.com
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/ntb/ntb_transport.c

@@ -102,6 +102,9 @@ struct ntb_queue_entry {
 	void *buf;
 	unsigned int len;
 	unsigned int flags;
+	int retries;
+	int errors;
+	unsigned int tx_index;
 
 	struct ntb_transport_qp *qp;
 	union {
@@ -259,6 +262,9 @@ enum {
 static void ntb_transport_rxc_db(unsigned long data);
 static const struct ntb_ctx_ops ntb_transport_ops;
 static struct ntb_client ntb_transport_client;
+static int ntb_async_tx_submit(struct ntb_transport_qp *qp,
+			       struct ntb_queue_entry *entry);
+static void ntb_memcpy_tx(struct ntb_queue_entry *entry, void __iomem *offset);
 
 static int ntb_transport_bus_match(struct device *dev,
 				   struct device_driver *drv)
@@ -1467,12 +1473,39 @@ static void ntb_transport_rxc_db(unsigned long data)
 	}
 }
 
-static void ntb_tx_copy_callback(void *data)
+static void ntb_tx_copy_callback(void *data,
+				 const struct dmaengine_result *res)
 {
 	struct ntb_queue_entry *entry = data;
 	struct ntb_transport_qp *qp = entry->qp;
 	struct ntb_payload_header __iomem *hdr = entry->tx_hdr;
 
+	/* we need to check DMA results if we are using DMA */
+	if (res) {
+		enum dmaengine_tx_result dma_err = res->result;
+
+		switch (dma_err) {
+		case DMA_TRANS_READ_FAILED:
+		case DMA_TRANS_WRITE_FAILED:
+			entry->errors++;
+		case DMA_TRANS_ABORTED:
+		{
+			void __iomem *offset =
+				qp->tx_mw + qp->tx_max_frame *
+				entry->tx_index;
+
+			/* resubmit via CPU */
+			ntb_memcpy_tx(entry, offset);
+			qp->tx_memcpy++;
+			return;
+		}
+
+		case DMA_TRANS_NOERROR:
+		default:
+			break;
+		}
+	}
+
 	iowrite32(entry->flags | DESC_DONE_FLAG, &hdr->flags);
 
 	ntb_peer_db_set(qp->ndev, BIT_ULL(qp->qp_num));
@@ -1507,40 +1540,25 @@ static void ntb_memcpy_tx(struct ntb_queue_entry *entry, void __iomem *offset)
 	/* Ensure that the data is fully copied out before setting the flags */
 	wmb();
 
-	ntb_tx_copy_callback(entry);
+	ntb_tx_copy_callback(entry, NULL);
 }
 
-static void ntb_async_tx(struct ntb_transport_qp *qp,
-			 struct ntb_queue_entry *entry)
+static int ntb_async_tx_submit(struct ntb_transport_qp *qp,
+			       struct ntb_queue_entry *entry)
 {
-	struct ntb_payload_header __iomem *hdr;
 	struct dma_async_tx_descriptor *txd;
 	struct dma_chan *chan = qp->tx_dma_chan;
 	struct dma_device *device;
+	size_t len = entry->len;
+	void *buf = entry->buf;
 	size_t dest_off, buff_off;
 	struct dmaengine_unmap_data *unmap;
 	dma_addr_t dest;
 	dma_cookie_t cookie;
-	void __iomem *offset;
-	size_t len = entry->len;
-	void *buf = entry->buf;
 	int retries = 0;
 
-	offset = qp->tx_mw + qp->tx_max_frame * qp->tx_index;
-	hdr = offset + qp->tx_max_frame - sizeof(struct ntb_payload_header);
-	entry->tx_hdr = hdr;
-
-	iowrite32(entry->len, &hdr->len);
-	iowrite32((u32)qp->tx_pkts, &hdr->ver);
-
-	if (!chan)
-		goto err;
-
-	if (len < copy_bytes)
-		goto err;
-
 	device = chan->device;
-	dest = qp->tx_mw_phys + qp->tx_max_frame * qp->tx_index;
+	dest = qp->tx_mw_phys + qp->tx_max_frame * entry->tx_index;
 	buff_off = (size_t)buf & ~PAGE_MASK;
 	dest_off = (size_t)dest & ~PAGE_MASK;
 
@@ -1560,8 +1578,9 @@ static void ntb_async_tx(struct ntb_transport_qp *qp,
 	unmap->to_cnt = 1;
 
 	for (retries = 0; retries < DMA_RETRIES; retries++) {
-		txd = device->device_prep_dma_memcpy(chan, dest, unmap->addr[0],
-						     len, DMA_PREP_INTERRUPT);
+		txd = device->device_prep_dma_memcpy(chan, dest,
+						     unmap->addr[0], len,
+						     DMA_PREP_INTERRUPT);
 		if (txd)
 			break;
 
@@ -1574,7 +1593,7 @@ static void ntb_async_tx(struct ntb_transport_qp *qp,
 		goto err_get_unmap;
 	}
 
-	txd->callback = ntb_tx_copy_callback;
+	txd->callback_result = ntb_tx_copy_callback;
 	txd->callback_param = entry;
 	dma_set_unmap(txd, unmap);
 
@@ -1585,13 +1604,47 @@ static void ntb_async_tx(struct ntb_transport_qp *qp,
 	dmaengine_unmap_put(unmap);
 
 	dma_async_issue_pending(chan);
-	qp->tx_async++;
 
-	return;
+	return 0;
 err_set_unmap:
 	dmaengine_unmap_put(unmap);
 err_get_unmap:
 	dmaengine_unmap_put(unmap);
+err:
+	return -ENXIO;
+}
+
+static void ntb_async_tx(struct ntb_transport_qp *qp,
+			 struct ntb_queue_entry *entry)
+{
+	struct ntb_payload_header __iomem *hdr;
+	struct dma_chan *chan = qp->tx_dma_chan;
+	void __iomem *offset;
+	int res;
+
+	entry->tx_index = qp->tx_index;
+	offset = qp->tx_mw + qp->tx_max_frame * entry->tx_index;
+	hdr = offset + qp->tx_max_frame - sizeof(struct ntb_payload_header);
+	entry->tx_hdr = hdr;
+
+	iowrite32(entry->len, &hdr->len);
+	iowrite32((u32)qp->tx_pkts, &hdr->ver);
+
+	if (!chan)
+		goto err;
+
+	if (entry->len < copy_bytes)
+		goto err;
+
+	res = ntb_async_tx_submit(qp, entry);
+	if (res < 0)
+		goto err;
+
+	if (!entry->retries)
+		qp->tx_async++;
+
+	return;
+
 err:
 	ntb_memcpy_tx(entry, offset);
 	qp->tx_memcpy++;
@@ -1970,6 +2023,9 @@ int ntb_transport_tx_enqueue(struct ntb_transport_qp *qp, void *cb, void *data,
 	entry->buf = data;
 	entry->len = len;
 	entry->flags = 0;
+	entry->errors = 0;
+	entry->retries = 0;
+	entry->tx_index = 0;
 
 	rc = ntb_process_tx(qp, entry);
 	if (rc)