Merge branch 'net-axienet-introduce-dmaengine'

Radhey Shyam Pandey says:

====================
net: axienet: Introduce dmaengine

The axiethernet driver can use the dmaengine framework to communicate
with the xilinx DMAengine driver(AXIDMA, MCDMA). The inspiration behind
this dmaengine adoption is to reuse the in-kernel xilinx dma engine
driver[1] and remove redundant dma programming sequence[2] from the
ethernet driver. This simplifies the ethernet driver and also makes
it generic to be hooked to any complaint dma IP i.e AXIDMA, MCDMA
without any modification.

The dmaengine framework was extended for metadata API support during
the axidma RFC[3] discussion. However, it still needs further
enhancements to make it well suited for ethernet usecases.

Comments, suggestions, thoughts to implement remaining functional
features are very welcome!

[1]: https://github.com/torvalds/linux/blob/master/drivers/dma/xilinx/xilinx_dma.c
[2]: https://github.com/torvalds/linux/blob/master/drivers/net/ethernet/xilinx/xilinx_axienet_main.c#L238
[3]: http://lkml.iu.edu/hypermail/linux/kernel/1804.0/00367.html
[4]: https://lore.kernel.org/all/20221124102745.2620370-1-sarath.babu.naidu.gaddam@amd.com
====================

Link: https://lore.kernel.org/r/1700074613-1977070-1-git-send-email-radhey.shyam.pandey@amd.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/devicetree/bindings/net/xlnx,axi-ethernet.yaml

@@ -122,6 +122,20 @@ properties:
       and "phy-handle" should point to an external PHY if exists.
     maxItems: 1
 
+  dmas:
+    minItems: 2
+    maxItems: 32
+    description: TX and RX DMA channel phandle
+
+  dma-names:
+    items:
+      pattern: "^[tr]x_chan([0-9]|1[0-5])$"
+    description:
+      Should be "tx_chan0", "tx_chan1" ... "tx_chan15" for DMA Tx channel
+      Should be "rx_chan0", "rx_chan1" ... "rx_chan15" for DMA Rx channel
+    minItems: 2
+    maxItems: 32
+
 required:
   - compatible
   - interrupts
@@ -143,6 +157,8 @@ examples:
         clocks = <&axi_clk>, <&axi_clk>, <&pl_enet_ref_clk>, <&mgt_clk>;
         phy-mode = "mii";
         reg = <0x40c00000 0x40000>,<0x50c00000 0x40000>;
+        dmas = <&xilinx_dma 0>, <&xilinx_dma 1>;
+        dma-names = "tx_chan0", "rx_chan0";
         xlnx,rxcsum = <0x2>;
         xlnx,rxmem = <0x800>;
         xlnx,txcsum = <0x2>;

drivers/net/ethernet/xilinx/Kconfig

@@ -26,6 +26,7 @@ config XILINX_EMACLITE
 config XILINX_AXI_EMAC
 	tristate "Xilinx 10/100/1000 AXI Ethernet support"
 	depends on HAS_IOMEM
+	depends on XILINX_DMA
 	select PHYLINK
 	help
 	  This driver supports the 10/100/1000 Ethernet from Xilinx for the

drivers/net/ethernet/xilinx/xilinx_axienet.h

@@ -14,6 +14,7 @@
 #include <linux/interrupt.h>
 #include <linux/if_vlan.h>
 #include <linux/phylink.h>
+#include <linux/skbuff.h>
 
 /* Packet size info */
 #define XAE_HDR_SIZE			14 /* Size of Ethernet header */
@@ -378,6 +379,22 @@ struct axidma_bd {
 
 #define XAE_NUM_MISC_CLOCKS 3
 
+/**
+ * struct skbuf_dma_descriptor - skb for each dma descriptor
+ * @sgl: Pointer for sglist.
+ * @desc: Pointer to dma descriptor.
+ * @dma_address: dma address of sglist.
+ * @skb: Pointer to SKB transferred using DMA
+ * @sg_len: number of entries in the sglist.
+ */
+struct skbuf_dma_descriptor {
+	struct scatterlist sgl[MAX_SKB_FRAGS + 1];
+	struct dma_async_tx_descriptor *desc;
+	dma_addr_t dma_address;
+	struct sk_buff *skb;
+	int sg_len;
+};
+
 /**
  * struct axienet_local - axienet private per device data
  * @ndev:	Pointer for net_device to which it will be attached.
@@ -435,6 +452,15 @@ struct axidma_bd {
  * @coalesce_usec_rx:	IRQ coalesce delay for RX
  * @coalesce_count_tx:	Store the irq coalesce on TX side.
  * @coalesce_usec_tx:	IRQ coalesce delay for TX
+ * @use_dmaengine: flag to check dmaengine framework usage.
+ * @tx_chan:	TX DMA channel.
+ * @rx_chan:	RX DMA channel.
+ * @tx_skb_ring: Pointer to TX skb ring buffer array.
+ * @rx_skb_ring: Pointer to RX skb ring buffer array.
+ * @tx_ring_head: TX skb ring buffer head index.
+ * @tx_ring_tail: TX skb ring buffer tail index.
+ * @rx_ring_head: RX skb ring buffer head index.
+ * @rx_ring_tail: RX skb ring buffer tail index.
  */
 struct axienet_local {
 	struct net_device *ndev;
@@ -499,6 +525,15 @@ struct axienet_local {
 	u32 coalesce_usec_rx;
 	u32 coalesce_count_tx;
 	u32 coalesce_usec_tx;
+	u8  use_dmaengine;
+	struct dma_chan *tx_chan;
+	struct dma_chan *rx_chan;
+	struct skbuf_dma_descriptor **tx_skb_ring;
+	struct skbuf_dma_descriptor **rx_skb_ring;
+	int tx_ring_head;
+	int tx_ring_tail;
+	int rx_ring_head;
+	int rx_ring_tail;
 };
 
 /**

drivers/net/ethernet/xilinx/xilinx_axienet_main.c

@@ -38,6 +38,11 @@
 #include <linux/phy.h>
 #include <linux/mii.h>
 #include <linux/ethtool.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/dma/xilinx_dma.h>
+#include <linux/circ_buf.h>
+#include <net/netdev_queues.h>
 
 #include "xilinx_axienet.h"
 
@@ -47,6 +52,9 @@
 #define TX_BD_NUM_MIN			(MAX_SKB_FRAGS + 1)
 #define TX_BD_NUM_MAX			4096
 #define RX_BD_NUM_MAX			4096
+#define DMA_NUM_APP_WORDS		5
+#define LEN_APP				4
+#define RX_BUF_NUM_DEFAULT		128
 
 /* Must be shorter than length of ethtool_drvinfo.driver field to fit */
 #define DRIVER_NAME		"xaxienet"
@@ -55,6 +63,8 @@
 
 #define AXIENET_REGS_N		40
 
+static void axienet_rx_submit_desc(struct net_device *ndev);
+
 /* Match table for of_platform binding */
 static const struct of_device_id axienet_of_match[] = {
 	{ .compatible = "xlnx,axi-ethernet-1.00.a", },
@@ -120,6 +130,16 @@ static struct axienet_option axienet_options[] = {
 	{}
 };
 
+static struct skbuf_dma_descriptor *axienet_get_rx_desc(struct axienet_local *lp, int i)
+{
+	return lp->rx_skb_ring[i & (RX_BUF_NUM_DEFAULT - 1)];
+}
+
+static struct skbuf_dma_descriptor *axienet_get_tx_desc(struct axienet_local *lp, int i)
+{
+	return lp->tx_skb_ring[i & (TX_BD_NUM_MAX - 1)];
+}
+
 /**
  * axienet_dma_in32 - Memory mapped Axi DMA register read
  * @lp:		Pointer to axienet local structure
@@ -589,10 +609,6 @@ static int axienet_device_reset(struct net_device *ndev)
 	struct axienet_local *lp = netdev_priv(ndev);
 	int ret;
 
-	ret = __axienet_device_reset(lp);
-	if (ret)
-		return ret;
-
 	lp->max_frm_size = XAE_MAX_VLAN_FRAME_SIZE;
 	lp->options |= XAE_OPTION_VLAN;
 	lp->options &= (~XAE_OPTION_JUMBO);
@@ -606,11 +622,17 @@ static int axienet_device_reset(struct net_device *ndev)
 			lp->options |= XAE_OPTION_JUMBO;
 	}
 
-	ret = axienet_dma_bd_init(ndev);
-	if (ret) {
-		netdev_err(ndev, "%s: descriptor allocation failed\n",
-			   __func__);
-		return ret;
+	if (!lp->use_dmaengine) {
+		ret = __axienet_device_reset(lp);
+		if (ret)
+			return ret;
+
+		ret = axienet_dma_bd_init(ndev);
+		if (ret) {
+			netdev_err(ndev, "%s: descriptor allocation failed\n",
+				   __func__);
+			return ret;
+		}
 	}
 
 	axienet_status = axienet_ior(lp, XAE_RCW1_OFFSET);
@@ -725,6 +747,128 @@ static inline int axienet_check_tx_bd_space(struct axienet_local *lp,
 	return 0;
 }
 
+/**
+ * axienet_dma_tx_cb - DMA engine callback for TX channel.
+ * @data:       Pointer to the axienet_local structure.
+ * @result:     error reporting through dmaengine_result.
+ * This function is called by dmaengine driver for TX channel to notify
+ * that the transmit is done.
+ */
+static void axienet_dma_tx_cb(void *data, const struct dmaengine_result *result)
+{
+	struct skbuf_dma_descriptor *skbuf_dma;
+	struct axienet_local *lp = data;
+	struct netdev_queue *txq;
+	int len;
+
+	skbuf_dma = axienet_get_tx_desc(lp, lp->tx_ring_tail++);
+	len = skbuf_dma->skb->len;
+	txq = skb_get_tx_queue(lp->ndev, skbuf_dma->skb);
+	u64_stats_update_begin(&lp->tx_stat_sync);
+	u64_stats_add(&lp->tx_bytes, len);
+	u64_stats_add(&lp->tx_packets, 1);
+	u64_stats_update_end(&lp->tx_stat_sync);
+	dma_unmap_sg(lp->dev, skbuf_dma->sgl, skbuf_dma->sg_len, DMA_TO_DEVICE);
+	dev_consume_skb_any(skbuf_dma->skb);
+	netif_txq_completed_wake(txq, 1, len,
+				 CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX),
+				 2 * MAX_SKB_FRAGS);
+}
+
+/**
+ * axienet_start_xmit_dmaengine - Starts the transmission.
+ * @skb:        sk_buff pointer that contains data to be Txed.
+ * @ndev:       Pointer to net_device structure.
+ *
+ * Return: NETDEV_TX_OK on success or any non space errors.
+ *         NETDEV_TX_BUSY when free element in TX skb ring buffer
+ *         is not available.
+ *
+ * This function is invoked to initiate transmission. The
+ * function sets the skbs, register dma callback API and submit
+ * the dma transaction.
+ * Additionally if checksum offloading is supported,
+ * it populates AXI Stream Control fields with appropriate values.
+ */
+static netdev_tx_t
+axienet_start_xmit_dmaengine(struct sk_buff *skb, struct net_device *ndev)
+{
+	struct dma_async_tx_descriptor *dma_tx_desc = NULL;
+	struct axienet_local *lp = netdev_priv(ndev);
+	u32 app_metadata[DMA_NUM_APP_WORDS] = {0};
+	struct skbuf_dma_descriptor *skbuf_dma;
+	struct dma_device *dma_dev;
+	struct netdev_queue *txq;
+	u32 csum_start_off;
+	u32 csum_index_off;
+	int sg_len;
+	int ret;
+
+	dma_dev = lp->tx_chan->device;
+	sg_len = skb_shinfo(skb)->nr_frags + 1;
+	if (CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX) <= sg_len) {
+		netif_stop_queue(ndev);
+		if (net_ratelimit())
+			netdev_warn(ndev, "TX ring unexpectedly full\n");
+		return NETDEV_TX_BUSY;
+	}
+
+	skbuf_dma = axienet_get_tx_desc(lp, lp->tx_ring_head);
+	if (!skbuf_dma)
+		goto xmit_error_drop_skb;
+
+	lp->tx_ring_head++;
+	sg_init_table(skbuf_dma->sgl, sg_len);
+	ret = skb_to_sgvec(skb, skbuf_dma->sgl, 0, skb->len);
+	if (ret < 0)
+		goto xmit_error_drop_skb;
+
+	ret = dma_map_sg(lp->dev, skbuf_dma->sgl, sg_len, DMA_TO_DEVICE);
+	if (!ret)
+		goto xmit_error_drop_skb;
+
+	/* Fill up app fields for checksum */
+	if (skb->ip_summed == CHECKSUM_PARTIAL) {
+		if (lp->features & XAE_FEATURE_FULL_TX_CSUM) {
+			/* Tx Full Checksum Offload Enabled */
+			app_metadata[0] |= 2;
+		} else if (lp->features & XAE_FEATURE_PARTIAL_TX_CSUM) {
+			csum_start_off = skb_transport_offset(skb);
+			csum_index_off = csum_start_off + skb->csum_offset;
+			/* Tx Partial Checksum Offload Enabled */
+			app_metadata[0] |= 1;
+			app_metadata[1] = (csum_start_off << 16) | csum_index_off;
+		}
+	} else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
+		app_metadata[0] |= 2; /* Tx Full Checksum Offload Enabled */
+	}
+
+	dma_tx_desc = dma_dev->device_prep_slave_sg(lp->tx_chan, skbuf_dma->sgl,
+			sg_len, DMA_MEM_TO_DEV,
+			DMA_PREP_INTERRUPT, (void *)app_metadata);
+	if (!dma_tx_desc)
+		goto xmit_error_unmap_sg;
+
+	skbuf_dma->skb = skb;
+	skbuf_dma->sg_len = sg_len;
+	dma_tx_desc->callback_param = lp;
+	dma_tx_desc->callback_result = axienet_dma_tx_cb;
+	dmaengine_submit(dma_tx_desc);
+	dma_async_issue_pending(lp->tx_chan);
+	txq = skb_get_tx_queue(lp->ndev, skb);
+	netdev_tx_sent_queue(txq, skb->len);
+	netif_txq_maybe_stop(txq, CIRC_SPACE(lp->tx_ring_head, lp->tx_ring_tail, TX_BD_NUM_MAX),
+			     MAX_SKB_FRAGS + 1, 2 * MAX_SKB_FRAGS);
+
+	return NETDEV_TX_OK;
+
+xmit_error_unmap_sg:
+	dma_unmap_sg(lp->dev, skbuf_dma->sgl, sg_len, DMA_TO_DEVICE);
+xmit_error_drop_skb:
+	dev_kfree_skb_any(skb);
+	return NETDEV_TX_OK;
+}
+
 /**
  * axienet_tx_poll - Invoked once a transmit is completed by the
  * Axi DMA Tx channel.
@@ -891,6 +1035,42 @@ axienet_start_xmit(struct sk_buff *skb, struct net_device *ndev)
 	return NETDEV_TX_OK;
 }
 
+/**
+ * axienet_dma_rx_cb - DMA engine callback for RX channel.
+ * @data:       Pointer to the skbuf_dma_descriptor structure.
+ * @result:     error reporting through dmaengine_result.
+ * This function is called by dmaengine driver for RX channel to notify
+ * that the packet is received.
+ */
+static void axienet_dma_rx_cb(void *data, const struct dmaengine_result *result)
+{
+	struct skbuf_dma_descriptor *skbuf_dma;
+	size_t meta_len, meta_max_len, rx_len;
+	struct axienet_local *lp = data;
+	struct sk_buff *skb;
+	u32 *app_metadata;
+
+	skbuf_dma = axienet_get_rx_desc(lp, lp->rx_ring_tail++);
+	skb = skbuf_dma->skb;
+	app_metadata = dmaengine_desc_get_metadata_ptr(skbuf_dma->desc, &meta_len,
+						       &meta_max_len);
+	dma_unmap_single(lp->dev, skbuf_dma->dma_address, lp->max_frm_size,
+			 DMA_FROM_DEVICE);
+	/* TODO: Derive app word index programmatically */
+	rx_len = (app_metadata[LEN_APP] & 0xFFFF);
+	skb_put(skb, rx_len);
+	skb->protocol = eth_type_trans(skb, lp->ndev);
+	skb->ip_summed = CHECKSUM_NONE;
+
+	__netif_rx(skb);
+	u64_stats_update_begin(&lp->rx_stat_sync);
+	u64_stats_add(&lp->rx_packets, 1);
+	u64_stats_add(&lp->rx_bytes, rx_len);
+	u64_stats_update_end(&lp->rx_stat_sync);
+	axienet_rx_submit_desc(lp->ndev);
+	dma_async_issue_pending(lp->rx_chan);
+}
+
 /**
  * axienet_rx_poll - Triggered by RX ISR to complete the BD processing.
  * @napi:	Pointer to NAPI structure.
@@ -1125,41 +1305,159 @@ static irqreturn_t axienet_eth_irq(int irq, void *_ndev)
 static void axienet_dma_err_handler(struct work_struct *work);
 
 /**
- * axienet_open - Driver open routine.
- * @ndev:	Pointer to net_device structure
+ * axienet_rx_submit_desc - Submit the rx descriptors to dmaengine.
+ * allocate skbuff, map the scatterlist and obtain a descriptor
+ * and then add the callback information and submit descriptor.
+ *
+ * @ndev:	net_device pointer
+ *
+ */
+static void axienet_rx_submit_desc(struct net_device *ndev)
+{
+	struct dma_async_tx_descriptor *dma_rx_desc = NULL;
+	struct axienet_local *lp = netdev_priv(ndev);
+	struct skbuf_dma_descriptor *skbuf_dma;
+	struct sk_buff *skb;
+	dma_addr_t addr;
+
+	skbuf_dma = axienet_get_rx_desc(lp, lp->rx_ring_head);
+	if (!skbuf_dma)
+		return;
+
+	lp->rx_ring_head++;
+	skb = netdev_alloc_skb(ndev, lp->max_frm_size);
+	if (!skb)
+		return;
+
+	sg_init_table(skbuf_dma->sgl, 1);
+	addr = dma_map_single(lp->dev, skb->data, lp->max_frm_size, DMA_FROM_DEVICE);
+	if (unlikely(dma_mapping_error(lp->dev, addr))) {
+		if (net_ratelimit())
+			netdev_err(ndev, "DMA mapping error\n");
+		goto rx_submit_err_free_skb;
+	}
+	sg_dma_address(skbuf_dma->sgl) = addr;
+	sg_dma_len(skbuf_dma->sgl) = lp->max_frm_size;
+	dma_rx_desc = dmaengine_prep_slave_sg(lp->rx_chan, skbuf_dma->sgl,
+					      1, DMA_DEV_TO_MEM,
+					      DMA_PREP_INTERRUPT);
+	if (!dma_rx_desc)
+		goto rx_submit_err_unmap_skb;
+
+	skbuf_dma->skb = skb;
+	skbuf_dma->dma_address = sg_dma_address(skbuf_dma->sgl);
+	skbuf_dma->desc = dma_rx_desc;
+	dma_rx_desc->callback_param = lp;
+	dma_rx_desc->callback_result = axienet_dma_rx_cb;
+	dmaengine_submit(dma_rx_desc);
+
+	return;
+
+rx_submit_err_unmap_skb:
+	dma_unmap_single(lp->dev, addr, lp->max_frm_size, DMA_FROM_DEVICE);
+rx_submit_err_free_skb:
+	dev_kfree_skb(skb);
+}
+
+/**
+ * axienet_init_dmaengine - init the dmaengine code.
+ * @ndev:       Pointer to net_device structure
  *
  * Return: 0, on success.
- *	    non-zero error value on failure
+ *          non-zero error value on failure
  *
- * This is the driver open routine. It calls phylink_start to start the
- * PHY device.
- * It also allocates interrupt service routines, enables the interrupt lines
- * and ISR handling. Axi Ethernet core is reset through Axi DMA core. Buffer
- * descriptors are initialized.
+ * This is the dmaengine initialization code.
  */
-static int axienet_open(struct net_device *ndev)
+static int axienet_init_dmaengine(struct net_device *ndev)
+{
+	struct axienet_local *lp = netdev_priv(ndev);
+	struct skbuf_dma_descriptor *skbuf_dma;
+	int i, ret;
+
+	lp->tx_chan = dma_request_chan(lp->dev, "tx_chan0");
+	if (IS_ERR(lp->tx_chan)) {
+		dev_err(lp->dev, "No Ethernet DMA (TX) channel found\n");
+		return PTR_ERR(lp->tx_chan);
+	}
+
+	lp->rx_chan = dma_request_chan(lp->dev, "rx_chan0");
+	if (IS_ERR(lp->rx_chan)) {
+		ret = PTR_ERR(lp->rx_chan);
+		dev_err(lp->dev, "No Ethernet DMA (RX) channel found\n");
+		goto err_dma_release_tx;
+	}
+
+	lp->tx_ring_tail = 0;
+	lp->tx_ring_head = 0;
+	lp->rx_ring_tail = 0;
+	lp->rx_ring_head = 0;
+	lp->tx_skb_ring = kcalloc(TX_BD_NUM_MAX, sizeof(*lp->tx_skb_ring),
+				  GFP_KERNEL);
+	if (!lp->tx_skb_ring) {
+		ret = -ENOMEM;
+		goto err_dma_release_rx;
+	}
+	for (i = 0; i < TX_BD_NUM_MAX; i++) {
+		skbuf_dma = kzalloc(sizeof(*skbuf_dma), GFP_KERNEL);
+		if (!skbuf_dma) {
+			ret = -ENOMEM;
+			goto err_free_tx_skb_ring;
+		}
+		lp->tx_skb_ring[i] = skbuf_dma;
+	}
+
+	lp->rx_skb_ring = kcalloc(RX_BUF_NUM_DEFAULT, sizeof(*lp->rx_skb_ring),
+				  GFP_KERNEL);
+	if (!lp->rx_skb_ring) {
+		ret = -ENOMEM;
+		goto err_free_tx_skb_ring;
+	}
+	for (i = 0; i < RX_BUF_NUM_DEFAULT; i++) {
+		skbuf_dma = kzalloc(sizeof(*skbuf_dma), GFP_KERNEL);
+		if (!skbuf_dma) {
+			ret = -ENOMEM;
+			goto err_free_rx_skb_ring;
+		}
+		lp->rx_skb_ring[i] = skbuf_dma;
+	}
+	/* TODO: Instead of BD_NUM_DEFAULT use runtime support */
+	for (i = 0; i < RX_BUF_NUM_DEFAULT; i++)
+		axienet_rx_submit_desc(ndev);
+	dma_async_issue_pending(lp->rx_chan);
+
+	return 0;
+
+err_free_rx_skb_ring:
+	for (i = 0; i < RX_BUF_NUM_DEFAULT; i++)
+		kfree(lp->rx_skb_ring[i]);
+	kfree(lp->rx_skb_ring);
+err_free_tx_skb_ring:
+	for (i = 0; i < TX_BD_NUM_MAX; i++)
+		kfree(lp->tx_skb_ring[i]);
+	kfree(lp->tx_skb_ring);
+err_dma_release_rx:
+	dma_release_channel(lp->rx_chan);
+err_dma_release_tx:
+	dma_release_channel(lp->tx_chan);
+	return ret;
+}
+
+/**
+ * axienet_init_legacy_dma - init the dma legacy code.
+ * @ndev:       Pointer to net_device structure
+ *
+ * Return: 0, on success.
+ *          non-zero error value on failure
+ *
+ * This is the dma  initialization code. It also allocates interrupt
+ * service routines, enables the interrupt lines and ISR handling.
+ *
+ */
+static int axienet_init_legacy_dma(struct net_device *ndev)
 {
 	int ret;
 	struct axienet_local *lp = netdev_priv(ndev);
 
-	dev_dbg(&ndev->dev, "axienet_open()\n");
-
-	/* When we do an Axi Ethernet reset, it resets the complete core
-	 * including the MDIO. MDIO must be disabled before resetting.
-	 * Hold MDIO bus lock to avoid MDIO accesses during the reset.
-	 */
-	axienet_lock_mii(lp);
-	ret = axienet_device_reset(ndev);
-	axienet_unlock_mii(lp);
-
-	ret = phylink_of_phy_connect(lp->phylink, lp->dev->of_node, 0);
-	if (ret) {
-		dev_err(lp->dev, "phylink_of_phy_connect() failed: %d\n", ret);
-		return ret;
-	}
-
-	phylink_start(lp->phylink);
-
 	/* Enable worker thread for Axi DMA error handling */
 	INIT_WORK(&lp->dma_err_task, axienet_dma_err_handler);
 
@@ -1193,13 +1491,76 @@ err_rx_irq:
 err_tx_irq:
 	napi_disable(&lp->napi_tx);
 	napi_disable(&lp->napi_rx);
-	phylink_stop(lp->phylink);
-	phylink_disconnect_phy(lp->phylink);
 	cancel_work_sync(&lp->dma_err_task);
 	dev_err(lp->dev, "request_irq() failed\n");
 	return ret;
 }
 
+/**
+ * axienet_open - Driver open routine.
+ * @ndev:	Pointer to net_device structure
+ *
+ * Return: 0, on success.
+ *	    non-zero error value on failure
+ *
+ * This is the driver open routine. It calls phylink_start to start the
+ * PHY device.
+ * It also allocates interrupt service routines, enables the interrupt lines
+ * and ISR handling. Axi Ethernet core is reset through Axi DMA core. Buffer
+ * descriptors are initialized.
+ */
+static int axienet_open(struct net_device *ndev)
+{
+	int ret;
+	struct axienet_local *lp = netdev_priv(ndev);
+
+	dev_dbg(&ndev->dev, "%s\n", __func__);
+
+	/* When we do an Axi Ethernet reset, it resets the complete core
+	 * including the MDIO. MDIO must be disabled before resetting.
+	 * Hold MDIO bus lock to avoid MDIO accesses during the reset.
+	 */
+	axienet_lock_mii(lp);
+	ret = axienet_device_reset(ndev);
+	axienet_unlock_mii(lp);
+
+	ret = phylink_of_phy_connect(lp->phylink, lp->dev->of_node, 0);
+	if (ret) {
+		dev_err(lp->dev, "phylink_of_phy_connect() failed: %d\n", ret);
+		return ret;
+	}
+
+	phylink_start(lp->phylink);
+
+	if (lp->use_dmaengine) {
+		/* Enable interrupts for Axi Ethernet core (if defined) */
+		if (lp->eth_irq > 0) {
+			ret = request_irq(lp->eth_irq, axienet_eth_irq, IRQF_SHARED,
+					  ndev->name, ndev);
+			if (ret)
+				goto err_phy;
+		}
+
+		ret = axienet_init_dmaengine(ndev);
+		if (ret < 0)
+			goto err_free_eth_irq;
+	} else {
+		ret = axienet_init_legacy_dma(ndev);
+		if (ret)
+			goto err_phy;
+	}
+
+	return 0;
+
+err_free_eth_irq:
+	if (lp->eth_irq > 0)
+		free_irq(lp->eth_irq, ndev);
+err_phy:
+	phylink_stop(lp->phylink);
+	phylink_disconnect_phy(lp->phylink);
+	return ret;
+}
+
 /**
  * axienet_stop - Driver stop routine.
  * @ndev:	Pointer to net_device structure
@@ -1213,11 +1574,14 @@ err_tx_irq:
 static int axienet_stop(struct net_device *ndev)
 {
 	struct axienet_local *lp = netdev_priv(ndev);
+	int i;
 
 	dev_dbg(&ndev->dev, "axienet_close()\n");
 
-	napi_disable(&lp->napi_tx);
-	napi_disable(&lp->napi_rx);
+	if (!lp->use_dmaengine) {
+		napi_disable(&lp->napi_tx);
+		napi_disable(&lp->napi_rx);
+	}
 
 	phylink_stop(lp->phylink);
 	phylink_disconnect_phy(lp->phylink);
@@ -1225,18 +1589,33 @@ static int axienet_stop(struct net_device *ndev)
 	axienet_setoptions(ndev, lp->options &
 			   ~(XAE_OPTION_TXEN | XAE_OPTION_RXEN));
 
-	axienet_dma_stop(lp);
+	if (!lp->use_dmaengine) {
+		axienet_dma_stop(lp);
+		cancel_work_sync(&lp->dma_err_task);
+		free_irq(lp->tx_irq, ndev);
+		free_irq(lp->rx_irq, ndev);
+		axienet_dma_bd_release(ndev);
+	} else {
+		dmaengine_terminate_sync(lp->tx_chan);
+		dmaengine_synchronize(lp->tx_chan);
+		dmaengine_terminate_sync(lp->rx_chan);
+		dmaengine_synchronize(lp->rx_chan);
+
+		for (i = 0; i < TX_BD_NUM_MAX; i++)
+			kfree(lp->tx_skb_ring[i]);
+		kfree(lp->tx_skb_ring);
+		for (i = 0; i < RX_BUF_NUM_DEFAULT; i++)
+			kfree(lp->rx_skb_ring[i]);
+		kfree(lp->rx_skb_ring);
+
+		dma_release_channel(lp->rx_chan);
+		dma_release_channel(lp->tx_chan);
+	}
 
 	axienet_iow(lp, XAE_IE_OFFSET, 0);
 
-	cancel_work_sync(&lp->dma_err_task);
-
 	if (lp->eth_irq > 0)
 		free_irq(lp->eth_irq, ndev);
-	free_irq(lp->tx_irq, ndev);
-	free_irq(lp->rx_irq, ndev);
-
-	axienet_dma_bd_release(ndev);
 	return 0;
 }
 
@@ -1333,6 +1712,18 @@ static const struct net_device_ops axienet_netdev_ops = {
 #endif
 };
 
+static const struct net_device_ops axienet_netdev_dmaengine_ops = {
+	.ndo_open = axienet_open,
+	.ndo_stop = axienet_stop,
+	.ndo_start_xmit = axienet_start_xmit_dmaengine,
+	.ndo_get_stats64 = axienet_get_stats64,
+	.ndo_change_mtu	= axienet_change_mtu,
+	.ndo_set_mac_address = netdev_set_mac_address,
+	.ndo_validate_addr = eth_validate_addr,
+	.ndo_eth_ioctl = axienet_ioctl,
+	.ndo_set_rx_mode = axienet_set_multicast_list,
+};
+
 /**
  * axienet_ethtools_get_drvinfo - Get various Axi Ethernet driver information.
  * @ndev:	Pointer to net_device structure
@@ -1412,14 +1803,16 @@ static void axienet_ethtools_get_regs(struct net_device *ndev,
 	data[29] = axienet_ior(lp, XAE_FMI_OFFSET);
 	data[30] = axienet_ior(lp, XAE_AF0_OFFSET);
 	data[31] = axienet_ior(lp, XAE_AF1_OFFSET);
-	data[32] = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
-	data[33] = axienet_dma_in32(lp, XAXIDMA_TX_SR_OFFSET);
-	data[34] = axienet_dma_in32(lp, XAXIDMA_TX_CDESC_OFFSET);
-	data[35] = axienet_dma_in32(lp, XAXIDMA_TX_TDESC_OFFSET);
-	data[36] = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
-	data[37] = axienet_dma_in32(lp, XAXIDMA_RX_SR_OFFSET);
-	data[38] = axienet_dma_in32(lp, XAXIDMA_RX_CDESC_OFFSET);
-	data[39] = axienet_dma_in32(lp, XAXIDMA_RX_TDESC_OFFSET);
+	if (!lp->use_dmaengine) {
+		data[32] = axienet_dma_in32(lp, XAXIDMA_TX_CR_OFFSET);
+		data[33] = axienet_dma_in32(lp, XAXIDMA_TX_SR_OFFSET);
+		data[34] = axienet_dma_in32(lp, XAXIDMA_TX_CDESC_OFFSET);
+		data[35] = axienet_dma_in32(lp, XAXIDMA_TX_TDESC_OFFSET);
+		data[36] = axienet_dma_in32(lp, XAXIDMA_RX_CR_OFFSET);
+		data[37] = axienet_dma_in32(lp, XAXIDMA_RX_SR_OFFSET);
+		data[38] = axienet_dma_in32(lp, XAXIDMA_RX_CDESC_OFFSET);
+		data[39] = axienet_dma_in32(lp, XAXIDMA_RX_TDESC_OFFSET);
+	}
 }
 
 static void
@@ -1863,7 +2256,6 @@ static int axienet_probe(struct platform_device *pdev)
 	SET_NETDEV_DEV(ndev, &pdev->dev);
 	ndev->flags &= ~IFF_MULTICAST;  /* clear multicast */
 	ndev->features = NETIF_F_SG;
-	ndev->netdev_ops = &axienet_netdev_ops;
 	ndev->ethtool_ops = &axienet_ethtool_ops;
 
 	/* MTU range: 64 - 9000 */
@@ -1880,9 +2272,6 @@ static int axienet_probe(struct platform_device *pdev)
 	u64_stats_init(&lp->rx_stat_sync);
 	u64_stats_init(&lp->tx_stat_sync);
 
-	netif_napi_add(ndev, &lp->napi_rx, axienet_rx_poll);
-	netif_napi_add(ndev, &lp->napi_tx, axienet_tx_poll);
-
 	lp->axi_clk = devm_clk_get_optional(&pdev->dev, "s_axi_lite_clk");
 	if (!lp->axi_clk) {
 		/* For backward compatibility, if named AXI clock is not present,
@@ -2008,82 +2397,118 @@ static int axienet_probe(struct platform_device *pdev)
 		goto cleanup_clk;
 	}
 
-	/* Find the DMA node, map the DMA registers, and decode the DMA IRQs */
-	np = of_parse_phandle(pdev->dev.of_node, "axistream-connected", 0);
-	if (np) {
-		struct resource dmares;
+	if (!of_find_property(pdev->dev.of_node, "dmas", NULL)) {
+		/* Find the DMA node, map the DMA registers, and decode the DMA IRQs */
+		np = of_parse_phandle(pdev->dev.of_node, "axistream-connected", 0);
 
-		ret = of_address_to_resource(np, 0, &dmares);
-		if (ret) {
-			dev_err(&pdev->dev,
-				"unable to get DMA resource\n");
+		if (np) {
+			struct resource dmares;
+
+			ret = of_address_to_resource(np, 0, &dmares);
+			if (ret) {
+				dev_err(&pdev->dev,
+					"unable to get DMA resource\n");
+				of_node_put(np);
+				goto cleanup_clk;
+			}
+			lp->dma_regs = devm_ioremap_resource(&pdev->dev,
+							     &dmares);
+			lp->rx_irq = irq_of_parse_and_map(np, 1);
+			lp->tx_irq = irq_of_parse_and_map(np, 0);
 			of_node_put(np);
+			lp->eth_irq = platform_get_irq_optional(pdev, 0);
+		} else {
+			/* Check for these resources directly on the Ethernet node. */
+			lp->dma_regs = devm_platform_get_and_ioremap_resource(pdev, 1, NULL);
+			lp->rx_irq = platform_get_irq(pdev, 1);
+			lp->tx_irq = platform_get_irq(pdev, 0);
+			lp->eth_irq = platform_get_irq_optional(pdev, 2);
+		}
+		if (IS_ERR(lp->dma_regs)) {
+			dev_err(&pdev->dev, "could not map DMA regs\n");
+			ret = PTR_ERR(lp->dma_regs);
 			goto cleanup_clk;
 		}
-		lp->dma_regs = devm_ioremap_resource(&pdev->dev,
-						     &dmares);
-		lp->rx_irq = irq_of_parse_and_map(np, 1);
-		lp->tx_irq = irq_of_parse_and_map(np, 0);
-		of_node_put(np);
-		lp->eth_irq = platform_get_irq_optional(pdev, 0);
-	} else {
-		/* Check for these resources directly on the Ethernet node. */
-		lp->dma_regs = devm_platform_get_and_ioremap_resource(pdev, 1, NULL);
-		lp->rx_irq = platform_get_irq(pdev, 1);
-		lp->tx_irq = platform_get_irq(pdev, 0);
-		lp->eth_irq = platform_get_irq_optional(pdev, 2);
-	}
-	if (IS_ERR(lp->dma_regs)) {
-		dev_err(&pdev->dev, "could not map DMA regs\n");
-		ret = PTR_ERR(lp->dma_regs);
-		goto cleanup_clk;
-	}
-	if ((lp->rx_irq <= 0) || (lp->tx_irq <= 0)) {
-		dev_err(&pdev->dev, "could not determine irqs\n");
-		ret = -ENOMEM;
-		goto cleanup_clk;
-	}
-
-	/* Reset core now that clocks are enabled, prior to accessing MDIO */
-	ret = __axienet_device_reset(lp);
-	if (ret)
-		goto cleanup_clk;
-
-	/* Autodetect the need for 64-bit DMA pointers.
-	 * When the IP is configured for a bus width bigger than 32 bits,
-	 * writing the MSB registers is mandatory, even if they are all 0.
-	 * We can detect this case by writing all 1's to one such register
-	 * and see if that sticks: when the IP is configured for 32 bits
-	 * only, those registers are RES0.
-	 * Those MSB registers were introduced in IP v7.1, which we check first.
-	 */
-	if ((axienet_ior(lp, XAE_ID_OFFSET) >> 24) >= 0x9) {
-		void __iomem *desc = lp->dma_regs + XAXIDMA_TX_CDESC_OFFSET + 4;
-
-		iowrite32(0x0, desc);
-		if (ioread32(desc) == 0) {	/* sanity check */
-			iowrite32(0xffffffff, desc);
-			if (ioread32(desc) > 0) {
-				lp->features |= XAE_FEATURE_DMA_64BIT;
-				addr_width = 64;
-				dev_info(&pdev->dev,
-					 "autodetected 64-bit DMA range\n");
-			}
-			iowrite32(0x0, desc);
+		if (lp->rx_irq <= 0 || lp->tx_irq <= 0) {
+			dev_err(&pdev->dev, "could not determine irqs\n");
+			ret = -ENOMEM;
+			goto cleanup_clk;
 		}
-	}
-	if (!IS_ENABLED(CONFIG_64BIT) && lp->features & XAE_FEATURE_DMA_64BIT) {
-		dev_err(&pdev->dev, "64-bit addressable DMA is not compatible with 32-bit archecture\n");
-		ret = -EINVAL;
-		goto cleanup_clk;
-	}
-
-	ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(addr_width));
-	if (ret) {
-		dev_err(&pdev->dev, "No suitable DMA available\n");
-		goto cleanup_clk;
+
+		/* Reset core now that clocks are enabled, prior to accessing MDIO */
+		ret = __axienet_device_reset(lp);
+		if (ret)
+			goto cleanup_clk;
+
+		/* Autodetect the need for 64-bit DMA pointers.
+		 * When the IP is configured for a bus width bigger than 32 bits,
+		 * writing the MSB registers is mandatory, even if they are all 0.
+		 * We can detect this case by writing all 1's to one such register
+		 * and see if that sticks: when the IP is configured for 32 bits
+		 * only, those registers are RES0.
+		 * Those MSB registers were introduced in IP v7.1, which we check first.
+		 */
+		if ((axienet_ior(lp, XAE_ID_OFFSET) >> 24) >= 0x9) {
+			void __iomem *desc = lp->dma_regs + XAXIDMA_TX_CDESC_OFFSET + 4;
+
+			iowrite32(0x0, desc);
+			if (ioread32(desc) == 0) {	/* sanity check */
+				iowrite32(0xffffffff, desc);
+				if (ioread32(desc) > 0) {
+					lp->features |= XAE_FEATURE_DMA_64BIT;
+					addr_width = 64;
+					dev_info(&pdev->dev,
+						 "autodetected 64-bit DMA range\n");
+				}
+				iowrite32(0x0, desc);
+			}
+		}
+		if (!IS_ENABLED(CONFIG_64BIT) && lp->features & XAE_FEATURE_DMA_64BIT) {
+			dev_err(&pdev->dev, "64-bit addressable DMA is not compatible with 32-bit archecture\n");
+			ret = -EINVAL;
+			goto cleanup_clk;
+		}
+
+		ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(addr_width));
+		if (ret) {
+			dev_err(&pdev->dev, "No suitable DMA available\n");
+			goto cleanup_clk;
+		}
+		netif_napi_add(ndev, &lp->napi_rx, axienet_rx_poll);
+		netif_napi_add(ndev, &lp->napi_tx, axienet_tx_poll);
+	} else {
+		struct xilinx_vdma_config cfg;
+		struct dma_chan *tx_chan;
+
+		lp->eth_irq = platform_get_irq_optional(pdev, 0);
+		if (lp->eth_irq < 0 && lp->eth_irq != -ENXIO) {
+			ret = lp->eth_irq;
+			goto cleanup_clk;
+		}
+		tx_chan = dma_request_chan(lp->dev, "tx_chan0");
+		if (IS_ERR(tx_chan)) {
+			ret = PTR_ERR(tx_chan);
+			dev_err_probe(lp->dev, ret, "No Ethernet DMA (TX) channel found\n");
+			goto cleanup_clk;
+		}
+
+		cfg.reset = 1;
+		/* As name says VDMA but it has support for DMA channel reset */
+		ret = xilinx_vdma_channel_set_config(tx_chan, &cfg);
+		if (ret < 0) {
+			dev_err(&pdev->dev, "Reset channel failed\n");
+			dma_release_channel(tx_chan);
+			goto cleanup_clk;
+		}
+
+		dma_release_channel(tx_chan);
+		lp->use_dmaengine = 1;
 	}
 
+	if (lp->use_dmaengine)
+		ndev->netdev_ops = &axienet_netdev_dmaengine_ops;
+	else
+		ndev->netdev_ops = &axienet_netdev_ops;
 	/* Check for Ethernet core IRQ (optional) */
 	if (lp->eth_irq <= 0)
 		dev_info(&pdev->dev, "Ethernet core IRQ not defined\n");
@@ -2099,8 +2524,8 @@ static int axienet_probe(struct platform_device *pdev)
 	}
 
 	lp->coalesce_count_rx = XAXIDMA_DFT_RX_THRESHOLD;
-	lp->coalesce_usec_rx = XAXIDMA_DFT_RX_USEC;
 	lp->coalesce_count_tx = XAXIDMA_DFT_TX_THRESHOLD;
+	lp->coalesce_usec_rx = XAXIDMA_DFT_RX_USEC;
 	lp->coalesce_usec_tx = XAXIDMA_DFT_TX_USEC;
 
 	ret = axienet_mdio_setup(lp);