Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1029 insertions, 0 deletions

diff --git a/drivers/net/ethernet/arc/emac_main.c b/drivers/net/ethernet/arc/emac_main.c
new file mode 100644
index 000000000..ba0646b3b
--- /dev/null
+++ b/drivers/net/ethernet/arc/emac_main.c
@@ -0,0 +1,1029 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2004-2013 Synopsys, Inc. (www.synopsys.com)
+ *
+ * Driver for the ARC EMAC 10100 (hardware revision 5)
+ *
+ * Contributors:
+ *		Amit Bhor
+ *		Sameer Dhavale
+ *		Vineet Gupta
+ */
+
+#include <linux/crc32.h>
+#include <linux/etherdevice.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/of_mdio.h>
+#include <linux/of_net.h>
+#include <linux/of_platform.h>
+
+#include "emac.h"
+
+static void arc_emac_restart(struct net_device *ndev);
+
+/**
+ * arc_emac_tx_avail - Return the number of available slots in the tx ring.
+ * @priv: Pointer to ARC EMAC private data structure.
+ *
+ * returns: the number of slots available for transmission in tx the ring.
+ */
+static inline int arc_emac_tx_avail(struct arc_emac_priv *priv)
+{
+	return (priv->txbd_dirty + TX_BD_NUM - priv->txbd_curr - 1) % TX_BD_NUM;
+}
+
+/**
+ * arc_emac_adjust_link - Adjust the PHY link duplex.
+ * @ndev:	Pointer to the net_device structure.
+ *
+ * This function is called to change the duplex setting after auto negotiation
+ * is done by the PHY.
+ */
+static void arc_emac_adjust_link(struct net_device *ndev)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+	struct phy_device *phy_dev = ndev->phydev;
+	unsigned int reg, state_changed = 0;
+
+	if (priv->link != phy_dev->link) {
+		priv->link = phy_dev->link;
+		state_changed = 1;
+	}
+
+	if (priv->speed != phy_dev->speed) {
+		priv->speed = phy_dev->speed;
+		state_changed = 1;
+		if (priv->set_mac_speed)
+			priv->set_mac_speed(priv, priv->speed);
+	}
+
+	if (priv->duplex != phy_dev->duplex) {
+		reg = arc_reg_get(priv, R_CTRL);
+
+		if (phy_dev->duplex == DUPLEX_FULL)
+			reg |= ENFL_MASK;
+		else
+			reg &= ~ENFL_MASK;
+
+		arc_reg_set(priv, R_CTRL, reg);
+		priv->duplex = phy_dev->duplex;
+		state_changed = 1;
+	}
+
+	if (state_changed)
+		phy_print_status(phy_dev);
+}
+
+/**
+ * arc_emac_get_drvinfo - Get EMAC driver information.
+ * @ndev:	Pointer to net_device structure.
+ * @info:	Pointer to ethtool_drvinfo structure.
+ *
+ * This implements ethtool command for getting the driver information.
+ * Issue "ethtool -i ethX" under linux prompt to execute this function.
+ */
+static void arc_emac_get_drvinfo(struct net_device *ndev,
+				 struct ethtool_drvinfo *info)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+
+	strscpy(info->driver, priv->drv_name, sizeof(info->driver));
+}
+
+static const struct ethtool_ops arc_emac_ethtool_ops = {
+	.get_drvinfo	= arc_emac_get_drvinfo,
+	.get_link	= ethtool_op_get_link,
+	.get_link_ksettings = phy_ethtool_get_link_ksettings,
+	.set_link_ksettings = phy_ethtool_set_link_ksettings,
+};
+
+#define FIRST_OR_LAST_MASK	(FIRST_MASK | LAST_MASK)
+
+/**
+ * arc_emac_tx_clean - clears processed by EMAC Tx BDs.
+ * @ndev:	Pointer to the network device.
+ */
+static void arc_emac_tx_clean(struct net_device *ndev)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+	struct net_device_stats *stats = &ndev->stats;
+	unsigned int i;
+
+	for (i = 0; i < TX_BD_NUM; i++) {
+		unsigned int *txbd_dirty = &priv->txbd_dirty;
+		struct arc_emac_bd *txbd = &priv->txbd[*txbd_dirty];
+		struct buffer_state *tx_buff = &priv->tx_buff[*txbd_dirty];
+		struct sk_buff *skb = tx_buff->skb;
+		unsigned int info = le32_to_cpu(txbd->info);
+
+		if ((info & FOR_EMAC) || !txbd->data || !skb)
+			break;
+
+		if (unlikely(info & (DROP | DEFR | LTCL | UFLO))) {
+			stats->tx_errors++;
+			stats->tx_dropped++;
+
+			if (info & DEFR)
+				stats->tx_carrier_errors++;
+
+			if (info & LTCL)
+				stats->collisions++;
+
+			if (info & UFLO)
+				stats->tx_fifo_errors++;
+		} else if (likely(info & FIRST_OR_LAST_MASK)) {
+			stats->tx_packets++;
+			stats->tx_bytes += skb->len;
+		}
+
+		dma_unmap_single(&ndev->dev, dma_unmap_addr(tx_buff, addr),
+				 dma_unmap_len(tx_buff, len), DMA_TO_DEVICE);
+
+		/* return the sk_buff to system */
+		dev_consume_skb_irq(skb);
+
+		txbd->data = 0;
+		txbd->info = 0;
+		tx_buff->skb = NULL;
+
+		*txbd_dirty = (*txbd_dirty + 1) % TX_BD_NUM;
+	}
+
+	/* Ensure that txbd_dirty is visible to tx() before checking
+	 * for queue stopped.
+	 */
+	smp_mb();
+
+	if (netif_queue_stopped(ndev) && arc_emac_tx_avail(priv))
+		netif_wake_queue(ndev);
+}
+
+/**
+ * arc_emac_rx - processing of Rx packets.
+ * @ndev:	Pointer to the network device.
+ * @budget:	How many BDs to process on 1 call.
+ *
+ * returns:	Number of processed BDs
+ *
+ * Iterate through Rx BDs and deliver received packages to upper layer.
+ */
+static int arc_emac_rx(struct net_device *ndev, int budget)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+	unsigned int work_done;
+
+	for (work_done = 0; work_done < budget; work_done++) {
+		unsigned int *last_rx_bd = &priv->last_rx_bd;
+		struct net_device_stats *stats = &ndev->stats;
+		struct buffer_state *rx_buff = &priv->rx_buff[*last_rx_bd];
+		struct arc_emac_bd *rxbd = &priv->rxbd[*last_rx_bd];
+		unsigned int pktlen, info = le32_to_cpu(rxbd->info);
+		struct sk_buff *skb;
+		dma_addr_t addr;
+
+		if (unlikely((info & OWN_MASK) == FOR_EMAC))
+			break;
+
+		/* Make a note that we saw a packet at this BD.
+		 * So next time, driver starts from this + 1
+		 */
+		*last_rx_bd = (*last_rx_bd + 1) % RX_BD_NUM;
+
+		if (unlikely((info & FIRST_OR_LAST_MASK) !=
+			     FIRST_OR_LAST_MASK)) {
+			/* We pre-allocate buffers of MTU size so incoming
+			 * packets won't be split/chained.
+			 */
+			if (net_ratelimit())
+				netdev_err(ndev, "incomplete packet received\n");
+
+			/* Return ownership to EMAC */
+			rxbd->info = cpu_to_le32(FOR_EMAC | EMAC_BUFFER_SIZE);
+			stats->rx_errors++;
+			stats->rx_length_errors++;
+			continue;
+		}
+
+		/* Prepare the BD for next cycle. netif_receive_skb()
+		 * only if new skb was allocated and mapped to avoid holes
+		 * in the RX fifo.
+		 */
+		skb = netdev_alloc_skb_ip_align(ndev, EMAC_BUFFER_SIZE);
+		if (unlikely(!skb)) {
+			if (net_ratelimit())
+				netdev_err(ndev, "cannot allocate skb\n");
+			/* Return ownership to EMAC */
+			rxbd->info = cpu_to_le32(FOR_EMAC | EMAC_BUFFER_SIZE);
+			stats->rx_errors++;
+			stats->rx_dropped++;
+			continue;
+		}
+
+		addr = dma_map_single(&ndev->dev, (void *)skb->data,
+				      EMAC_BUFFER_SIZE, DMA_FROM_DEVICE);
+		if (dma_mapping_error(&ndev->dev, addr)) {
+			if (net_ratelimit())
+				netdev_err(ndev, "cannot map dma buffer\n");
+			dev_kfree_skb(skb);
+			/* Return ownership to EMAC */
+			rxbd->info = cpu_to_le32(FOR_EMAC | EMAC_BUFFER_SIZE);
+			stats->rx_errors++;
+			stats->rx_dropped++;
+			continue;
+		}
+
+		/* unmap previosly mapped skb */
+		dma_unmap_single(&ndev->dev, dma_unmap_addr(rx_buff, addr),
+				 dma_unmap_len(rx_buff, len), DMA_FROM_DEVICE);
+
+		pktlen = info & LEN_MASK;
+		stats->rx_packets++;
+		stats->rx_bytes += pktlen;
+		skb_put(rx_buff->skb, pktlen);
+		rx_buff->skb->dev = ndev;
+		rx_buff->skb->protocol = eth_type_trans(rx_buff->skb, ndev);
+
+		netif_receive_skb(rx_buff->skb);
+
+		rx_buff->skb = skb;
+		dma_unmap_addr_set(rx_buff, addr, addr);
+		dma_unmap_len_set(rx_buff, len, EMAC_BUFFER_SIZE);
+
+		rxbd->data = cpu_to_le32(addr);
+
+		/* Make sure pointer to data buffer is set */
+		wmb();
+
+		/* Return ownership to EMAC */
+		rxbd->info = cpu_to_le32(FOR_EMAC | EMAC_BUFFER_SIZE);
+	}
+
+	return work_done;
+}
+
+/**
+ * arc_emac_rx_miss_handle - handle R_MISS register
+ * @ndev:	Pointer to the net_device structure.
+ */
+static void arc_emac_rx_miss_handle(struct net_device *ndev)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+	struct net_device_stats *stats = &ndev->stats;
+	unsigned int miss;
+
+	miss = arc_reg_get(priv, R_MISS);
+	if (miss) {
+		stats->rx_errors += miss;
+		stats->rx_missed_errors += miss;
+		priv->rx_missed_errors += miss;
+	}
+}
+
+/**
+ * arc_emac_rx_stall_check - check RX stall
+ * @ndev:	Pointer to the net_device structure.
+ * @budget:	How many BDs requested to process on 1 call.
+ * @work_done:	How many BDs processed
+ *
+ * Under certain conditions EMAC stop reception of incoming packets and
+ * continuously increment R_MISS register instead of saving data into
+ * provided buffer. This function detect that condition and restart
+ * EMAC.
+ */
+static void arc_emac_rx_stall_check(struct net_device *ndev,
+				    int budget, unsigned int work_done)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+	struct arc_emac_bd *rxbd;
+
+	if (work_done)
+		priv->rx_missed_errors = 0;
+
+	if (priv->rx_missed_errors && budget) {
+		rxbd = &priv->rxbd[priv->last_rx_bd];
+		if (le32_to_cpu(rxbd->info) & FOR_EMAC) {
+			arc_emac_restart(ndev);
+			priv->rx_missed_errors = 0;
+		}
+	}
+}
+
+/**
+ * arc_emac_poll - NAPI poll handler.
+ * @napi:	Pointer to napi_struct structure.
+ * @budget:	How many BDs to process on 1 call.
+ *
+ * returns:	Number of processed BDs
+ */
+static int arc_emac_poll(struct napi_struct *napi, int budget)
+{
+	struct net_device *ndev = napi->dev;
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+	unsigned int work_done;
+
+	arc_emac_tx_clean(ndev);
+	arc_emac_rx_miss_handle(ndev);
+
+	work_done = arc_emac_rx(ndev, budget);
+	if (work_done < budget) {
+		napi_complete_done(napi, work_done);
+		arc_reg_or(priv, R_ENABLE, RXINT_MASK | TXINT_MASK);
+	}
+
+	arc_emac_rx_stall_check(ndev, budget, work_done);
+
+	return work_done;
+}
+
+/**
+ * arc_emac_intr - Global interrupt handler for EMAC.
+ * @irq:		irq number.
+ * @dev_instance:	device instance.
+ *
+ * returns: IRQ_HANDLED for all cases.
+ *
+ * ARC EMAC has only 1 interrupt line, and depending on bits raised in
+ * STATUS register we may tell what is a reason for interrupt to fire.
+ */
+static irqreturn_t arc_emac_intr(int irq, void *dev_instance)
+{
+	struct net_device *ndev = dev_instance;
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+	struct net_device_stats *stats = &ndev->stats;
+	unsigned int status;
+
+	status = arc_reg_get(priv, R_STATUS);
+	status &= ~MDIO_MASK;
+
+	/* Reset all flags except "MDIO complete" */
+	arc_reg_set(priv, R_STATUS, status);
+
+	if (status & (RXINT_MASK | TXINT_MASK)) {
+		if (likely(napi_schedule_prep(&priv->napi))) {
+			arc_reg_clr(priv, R_ENABLE, RXINT_MASK | TXINT_MASK);
+			__napi_schedule(&priv->napi);
+		}
+	}
+
+	if (status & ERR_MASK) {
+		/* MSER/RXCR/RXFR/RXFL interrupt fires on corresponding
+		 * 8-bit error counter overrun.
+		 */
+
+		if (status & MSER_MASK) {
+			stats->rx_missed_errors += 0x100;
+			stats->rx_errors += 0x100;
+			priv->rx_missed_errors += 0x100;
+			napi_schedule(&priv->napi);
+		}
+
+		if (status & RXCR_MASK) {
+			stats->rx_crc_errors += 0x100;
+			stats->rx_errors += 0x100;
+		}
+
+		if (status & RXFR_MASK) {
+			stats->rx_frame_errors += 0x100;
+			stats->rx_errors += 0x100;
+		}
+
+		if (status & RXFL_MASK) {
+			stats->rx_over_errors += 0x100;
+			stats->rx_errors += 0x100;
+		}
+	}
+
+	return IRQ_HANDLED;
+}
+
+#ifdef CONFIG_NET_POLL_CONTROLLER
+static void arc_emac_poll_controller(struct net_device *dev)
+{
+	disable_irq(dev->irq);
+	arc_emac_intr(dev->irq, dev);
+	enable_irq(dev->irq);
+}
+#endif
+
+/**
+ * arc_emac_open - Open the network device.
+ * @ndev:	Pointer to the network device.
+ *
+ * returns: 0, on success or non-zero error value on failure.
+ *
+ * This function sets the MAC address, requests and enables an IRQ
+ * for the EMAC device and starts the Tx queue.
+ * It also connects to the phy device.
+ */
+static int arc_emac_open(struct net_device *ndev)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+	struct phy_device *phy_dev = ndev->phydev;
+	int i;
+
+	phy_dev->autoneg = AUTONEG_ENABLE;
+	phy_dev->speed = 0;
+	phy_dev->duplex = 0;
+	linkmode_and(phy_dev->advertising, phy_dev->advertising,
+		     phy_dev->supported);
+
+	priv->last_rx_bd = 0;
+
+	/* Allocate and set buffers for Rx BD's */
+	for (i = 0; i < RX_BD_NUM; i++) {
+		dma_addr_t addr;
+		unsigned int *last_rx_bd = &priv->last_rx_bd;
+		struct arc_emac_bd *rxbd = &priv->rxbd[*last_rx_bd];
+		struct buffer_state *rx_buff = &priv->rx_buff[*last_rx_bd];
+
+		rx_buff->skb = netdev_alloc_skb_ip_align(ndev,
+							 EMAC_BUFFER_SIZE);
+		if (unlikely(!rx_buff->skb))
+			return -ENOMEM;
+
+		addr = dma_map_single(&ndev->dev, (void *)rx_buff->skb->data,
+				      EMAC_BUFFER_SIZE, DMA_FROM_DEVICE);
+		if (dma_mapping_error(&ndev->dev, addr)) {
+			netdev_err(ndev, "cannot dma map\n");
+			dev_kfree_skb(rx_buff->skb);
+			return -ENOMEM;
+		}
+		dma_unmap_addr_set(rx_buff, addr, addr);
+		dma_unmap_len_set(rx_buff, len, EMAC_BUFFER_SIZE);
+
+		rxbd->data = cpu_to_le32(addr);
+
+		/* Make sure pointer to data buffer is set */
+		wmb();
+
+		/* Return ownership to EMAC */
+		rxbd->info = cpu_to_le32(FOR_EMAC | EMAC_BUFFER_SIZE);
+
+		*last_rx_bd = (*last_rx_bd + 1) % RX_BD_NUM;
+	}
+
+	priv->txbd_curr = 0;
+	priv->txbd_dirty = 0;
+
+	/* Clean Tx BD's */
+	memset(priv->txbd, 0, TX_RING_SZ);
+
+	/* Initialize logical address filter */
+	arc_reg_set(priv, R_LAFL, 0);
+	arc_reg_set(priv, R_LAFH, 0);
+
+	/* Set BD ring pointers for device side */
+	arc_reg_set(priv, R_RX_RING, (unsigned int)priv->rxbd_dma);
+	arc_reg_set(priv, R_TX_RING, (unsigned int)priv->txbd_dma);
+
+	/* Enable interrupts */
+	arc_reg_set(priv, R_ENABLE, RXINT_MASK | TXINT_MASK | ERR_MASK);
+
+	/* Set CONTROL */
+	arc_reg_set(priv, R_CTRL,
+		    (RX_BD_NUM << 24) |	/* RX BD table length */
+		    (TX_BD_NUM << 16) |	/* TX BD table length */
+		    TXRN_MASK | RXRN_MASK);
+
+	napi_enable(&priv->napi);
+
+	/* Enable EMAC */
+	arc_reg_or(priv, R_CTRL, EN_MASK);
+
+	phy_start(ndev->phydev);
+
+	netif_start_queue(ndev);
+
+	return 0;
+}
+
+/**
+ * arc_emac_set_rx_mode - Change the receive filtering mode.
+ * @ndev:	Pointer to the network device.
+ *
+ * This function enables/disables promiscuous or all-multicast mode
+ * and updates the multicast filtering list of the network device.
+ */
+static void arc_emac_set_rx_mode(struct net_device *ndev)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+
+	if (ndev->flags & IFF_PROMISC) {
+		arc_reg_or(priv, R_CTRL, PROM_MASK);
+	} else {
+		arc_reg_clr(priv, R_CTRL, PROM_MASK);
+
+		if (ndev->flags & IFF_ALLMULTI) {
+			arc_reg_set(priv, R_LAFL, ~0);
+			arc_reg_set(priv, R_LAFH, ~0);
+		} else if (ndev->flags & IFF_MULTICAST) {
+			struct netdev_hw_addr *ha;
+			unsigned int filter[2] = { 0, 0 };
+			int bit;
+
+			netdev_for_each_mc_addr(ha, ndev) {
+				bit = ether_crc_le(ETH_ALEN, ha->addr) >> 26;
+				filter[bit >> 5] |= 1 << (bit & 31);
+			}
+
+			arc_reg_set(priv, R_LAFL, filter[0]);
+			arc_reg_set(priv, R_LAFH, filter[1]);
+		} else {
+			arc_reg_set(priv, R_LAFL, 0);
+			arc_reg_set(priv, R_LAFH, 0);
+		}
+	}
+}
+
+/**
+ * arc_free_tx_queue - free skb from tx queue
+ * @ndev:	Pointer to the network device.
+ *
+ * This function must be called while EMAC disable
+ */
+static void arc_free_tx_queue(struct net_device *ndev)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+	unsigned int i;
+
+	for (i = 0; i < TX_BD_NUM; i++) {
+		struct arc_emac_bd *txbd = &priv->txbd[i];
+		struct buffer_state *tx_buff = &priv->tx_buff[i];
+
+		if (tx_buff->skb) {
+			dma_unmap_single(&ndev->dev,
+					 dma_unmap_addr(tx_buff, addr),
+					 dma_unmap_len(tx_buff, len),
+					 DMA_TO_DEVICE);
+
+			/* return the sk_buff to system */
+			dev_kfree_skb_irq(tx_buff->skb);
+		}
+
+		txbd->info = 0;
+		txbd->data = 0;
+		tx_buff->skb = NULL;
+	}
+}
+
+/**
+ * arc_free_rx_queue - free skb from rx queue
+ * @ndev:	Pointer to the network device.
+ *
+ * This function must be called while EMAC disable
+ */
+static void arc_free_rx_queue(struct net_device *ndev)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+	unsigned int i;
+
+	for (i = 0; i < RX_BD_NUM; i++) {
+		struct arc_emac_bd *rxbd = &priv->rxbd[i];
+		struct buffer_state *rx_buff = &priv->rx_buff[i];
+
+		if (rx_buff->skb) {
+			dma_unmap_single(&ndev->dev,
+					 dma_unmap_addr(rx_buff, addr),
+					 dma_unmap_len(rx_buff, len),
+					 DMA_FROM_DEVICE);
+
+			/* return the sk_buff to system */
+			dev_kfree_skb_irq(rx_buff->skb);
+		}
+
+		rxbd->info = 0;
+		rxbd->data = 0;
+		rx_buff->skb = NULL;
+	}
+}
+
+/**
+ * arc_emac_stop - Close the network device.
+ * @ndev:	Pointer to the network device.
+ *
+ * This function stops the Tx queue, disables interrupts and frees the IRQ for
+ * the EMAC device.
+ * It also disconnects the PHY device associated with the EMAC device.
+ */
+static int arc_emac_stop(struct net_device *ndev)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+
+	napi_disable(&priv->napi);
+	netif_stop_queue(ndev);
+
+	phy_stop(ndev->phydev);
+
+	/* Disable interrupts */
+	arc_reg_clr(priv, R_ENABLE, RXINT_MASK | TXINT_MASK | ERR_MASK);
+
+	/* Disable EMAC */
+	arc_reg_clr(priv, R_CTRL, EN_MASK);
+
+	/* Return the sk_buff to system */
+	arc_free_tx_queue(ndev);
+	arc_free_rx_queue(ndev);
+
+	return 0;
+}
+
+/**
+ * arc_emac_stats - Get system network statistics.
+ * @ndev:	Pointer to net_device structure.
+ *
+ * Returns the address of the device statistics structure.
+ * Statistics are updated in interrupt handler.
+ */
+static struct net_device_stats *arc_emac_stats(struct net_device *ndev)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+	struct net_device_stats *stats = &ndev->stats;
+	unsigned long miss, rxerr;
+	u8 rxcrc, rxfram, rxoflow;
+
+	rxerr = arc_reg_get(priv, R_RXERR);
+	miss = arc_reg_get(priv, R_MISS);
+
+	rxcrc = rxerr;
+	rxfram = rxerr >> 8;
+	rxoflow = rxerr >> 16;
+
+	stats->rx_errors += miss;
+	stats->rx_errors += rxcrc + rxfram + rxoflow;
+
+	stats->rx_over_errors += rxoflow;
+	stats->rx_frame_errors += rxfram;
+	stats->rx_crc_errors += rxcrc;
+	stats->rx_missed_errors += miss;
+
+	return stats;
+}
+
+/**
+ * arc_emac_tx - Starts the data transmission.
+ * @skb:	sk_buff pointer that contains data to be Transmitted.
+ * @ndev:	Pointer to net_device structure.
+ *
+ * returns: NETDEV_TX_OK, on success
+ *		NETDEV_TX_BUSY, if any of the descriptors are not free.
+ *
+ * This function is invoked from upper layers to initiate transmission.
+ */
+static netdev_tx_t arc_emac_tx(struct sk_buff *skb, struct net_device *ndev)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+	unsigned int len, *txbd_curr = &priv->txbd_curr;
+	struct net_device_stats *stats = &ndev->stats;
+	__le32 *info = &priv->txbd[*txbd_curr].info;
+	dma_addr_t addr;
+
+	if (skb_padto(skb, ETH_ZLEN))
+		return NETDEV_TX_OK;
+
+	len = max_t(unsigned int, ETH_ZLEN, skb->len);
+
+	if (unlikely(!arc_emac_tx_avail(priv))) {
+		netif_stop_queue(ndev);
+		netdev_err(ndev, "BUG! Tx Ring full when queue awake!\n");
+		return NETDEV_TX_BUSY;
+	}
+
+	addr = dma_map_single(&ndev->dev, (void *)skb->data, len,
+			      DMA_TO_DEVICE);
+
+	if (unlikely(dma_mapping_error(&ndev->dev, addr))) {
+		stats->tx_dropped++;
+		stats->tx_errors++;
+		dev_kfree_skb_any(skb);
+		return NETDEV_TX_OK;
+	}
+	dma_unmap_addr_set(&priv->tx_buff[*txbd_curr], addr, addr);
+	dma_unmap_len_set(&priv->tx_buff[*txbd_curr], len, len);
+
+	priv->txbd[*txbd_curr].data = cpu_to_le32(addr);
+
+	/* Make sure pointer to data buffer is set */
+	wmb();
+
+	skb_tx_timestamp(skb);
+
+	*info = cpu_to_le32(FOR_EMAC | FIRST_OR_LAST_MASK | len);
+
+	/* Make sure info word is set */
+	wmb();
+
+	priv->tx_buff[*txbd_curr].skb = skb;
+
+	/* Increment index to point to the next BD */
+	*txbd_curr = (*txbd_curr + 1) % TX_BD_NUM;
+
+	/* Ensure that tx_clean() sees the new txbd_curr before
+	 * checking the queue status. This prevents an unneeded wake
+	 * of the queue in tx_clean().
+	 */
+	smp_mb();
+
+	if (!arc_emac_tx_avail(priv)) {
+		netif_stop_queue(ndev);
+		/* Refresh tx_dirty */
+		smp_mb();
+		if (arc_emac_tx_avail(priv))
+			netif_start_queue(ndev);
+	}
+
+	arc_reg_set(priv, R_STATUS, TXPL_MASK);
+
+	return NETDEV_TX_OK;
+}
+
+static void arc_emac_set_address_internal(struct net_device *ndev)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+	unsigned int addr_low, addr_hi;
+
+	addr_low = le32_to_cpu(*(__le32 *)&ndev->dev_addr[0]);
+	addr_hi = le16_to_cpu(*(__le16 *)&ndev->dev_addr[4]);
+
+	arc_reg_set(priv, R_ADDRL, addr_low);
+	arc_reg_set(priv, R_ADDRH, addr_hi);
+}
+
+/**
+ * arc_emac_set_address - Set the MAC address for this device.
+ * @ndev:	Pointer to net_device structure.
+ * @p:		6 byte Address to be written as MAC address.
+ *
+ * This function copies the HW address from the sockaddr structure to the
+ * net_device structure and updates the address in HW.
+ *
+ * returns:	-EBUSY if the net device is busy or 0 if the address is set
+ *		successfully.
+ */
+static int arc_emac_set_address(struct net_device *ndev, void *p)
+{
+	struct sockaddr *addr = p;
+
+	if (netif_running(ndev))
+		return -EBUSY;
+
+	if (!is_valid_ether_addr(addr->sa_data))
+		return -EADDRNOTAVAIL;
+
+	eth_hw_addr_set(ndev, addr->sa_data);
+
+	arc_emac_set_address_internal(ndev);
+
+	return 0;
+}
+
+/**
+ * arc_emac_restart - Restart EMAC
+ * @ndev:	Pointer to net_device structure.
+ *
+ * This function do hardware reset of EMAC in order to restore
+ * network packets reception.
+ */
+static void arc_emac_restart(struct net_device *ndev)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+	struct net_device_stats *stats = &ndev->stats;
+	int i;
+
+	if (net_ratelimit())
+		netdev_warn(ndev, "restarting stalled EMAC\n");
+
+	netif_stop_queue(ndev);
+
+	/* Disable interrupts */
+	arc_reg_clr(priv, R_ENABLE, RXINT_MASK | TXINT_MASK | ERR_MASK);
+
+	/* Disable EMAC */
+	arc_reg_clr(priv, R_CTRL, EN_MASK);
+
+	/* Return the sk_buff to system */
+	arc_free_tx_queue(ndev);
+
+	/* Clean Tx BD's */
+	priv->txbd_curr = 0;
+	priv->txbd_dirty = 0;
+	memset(priv->txbd, 0, TX_RING_SZ);
+
+	for (i = 0; i < RX_BD_NUM; i++) {
+		struct arc_emac_bd *rxbd = &priv->rxbd[i];
+		unsigned int info = le32_to_cpu(rxbd->info);
+
+		if (!(info & FOR_EMAC)) {
+			stats->rx_errors++;
+			stats->rx_dropped++;
+		}
+		/* Return ownership to EMAC */
+		rxbd->info = cpu_to_le32(FOR_EMAC | EMAC_BUFFER_SIZE);
+	}
+	priv->last_rx_bd = 0;
+
+	/* Make sure info is visible to EMAC before enable */
+	wmb();
+
+	/* Enable interrupts */
+	arc_reg_set(priv, R_ENABLE, RXINT_MASK | TXINT_MASK | ERR_MASK);
+
+	/* Enable EMAC */
+	arc_reg_or(priv, R_CTRL, EN_MASK);
+
+	netif_start_queue(ndev);
+}
+
+static const struct net_device_ops arc_emac_netdev_ops = {
+	.ndo_open		= arc_emac_open,
+	.ndo_stop		= arc_emac_stop,
+	.ndo_start_xmit		= arc_emac_tx,
+	.ndo_set_mac_address	= arc_emac_set_address,
+	.ndo_get_stats		= arc_emac_stats,
+	.ndo_set_rx_mode	= arc_emac_set_rx_mode,
+	.ndo_eth_ioctl		= phy_do_ioctl_running,
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	.ndo_poll_controller	= arc_emac_poll_controller,
+#endif
+};
+
+int arc_emac_probe(struct net_device *ndev, int interface)
+{
+	struct device *dev = ndev->dev.parent;
+	struct resource res_regs;
+	struct device_node *phy_node;
+	struct phy_device *phydev = NULL;
+	struct arc_emac_priv *priv;
+	unsigned int id, clock_frequency, irq;
+	int err;
+
+	/* Get PHY from device tree */
+	phy_node = of_parse_phandle(dev->of_node, "phy", 0);
+	if (!phy_node) {
+		dev_err(dev, "failed to retrieve phy description from device tree\n");
+		return -ENODEV;
+	}
+
+	/* Get EMAC registers base address from device tree */
+	err = of_address_to_resource(dev->of_node, 0, &res_regs);
+	if (err) {
+		dev_err(dev, "failed to retrieve registers base from device tree\n");
+		err = -ENODEV;
+		goto out_put_node;
+	}
+
+	/* Get IRQ from device tree */
+	irq = irq_of_parse_and_map(dev->of_node, 0);
+	if (!irq) {
+		dev_err(dev, "failed to retrieve <irq> value from device tree\n");
+		err = -ENODEV;
+		goto out_put_node;
+	}
+
+	ndev->netdev_ops = &arc_emac_netdev_ops;
+	ndev->ethtool_ops = &arc_emac_ethtool_ops;
+	ndev->watchdog_timeo = TX_TIMEOUT;
+
+	priv = netdev_priv(ndev);
+	priv->dev = dev;
+
+	priv->regs = devm_ioremap_resource(dev, &res_regs);
+	if (IS_ERR(priv->regs)) {
+		err = PTR_ERR(priv->regs);
+		goto out_put_node;
+	}
+
+	dev_dbg(dev, "Registers base address is 0x%p\n", priv->regs);
+
+	if (priv->clk) {
+		err = clk_prepare_enable(priv->clk);
+		if (err) {
+			dev_err(dev, "failed to enable clock\n");
+			goto out_put_node;
+		}
+
+		clock_frequency = clk_get_rate(priv->clk);
+	} else {
+		/* Get CPU clock frequency from device tree */
+		if (of_property_read_u32(dev->of_node, "clock-frequency",
+					 &clock_frequency)) {
+			dev_err(dev, "failed to retrieve <clock-frequency> from device tree\n");
+			err = -EINVAL;
+			goto out_put_node;
+		}
+	}
+
+	id = arc_reg_get(priv, R_ID);
+
+	/* Check for EMAC revision 5 or 7, magic number */
+	if (!(id == 0x0005fd02 || id == 0x0007fd02)) {
+		dev_err(dev, "ARC EMAC not detected, id=0x%x\n", id);
+		err = -ENODEV;
+		goto out_clken;
+	}
+	dev_info(dev, "ARC EMAC detected with id: 0x%x\n", id);
+
+	/* Set poll rate so that it polls every 1 ms */
+	arc_reg_set(priv, R_POLLRATE, clock_frequency / 1000000);
+
+	ndev->irq = irq;
+	dev_info(dev, "IRQ is %d\n", ndev->irq);
+
+	/* Register interrupt handler for device */
+	err = devm_request_irq(dev, ndev->irq, arc_emac_intr, 0,
+			       ndev->name, ndev);
+	if (err) {
+		dev_err(dev, "could not allocate IRQ\n");
+		goto out_clken;
+	}
+
+	/* Get MAC address from device tree */
+	err = of_get_ethdev_address(dev->of_node, ndev);
+	if (err)
+		eth_hw_addr_random(ndev);
+
+	arc_emac_set_address_internal(ndev);
+	dev_info(dev, "MAC address is now %pM\n", ndev->dev_addr);
+
+	/* Do 1 allocation instead of 2 separate ones for Rx and Tx BD rings */
+	priv->rxbd = dmam_alloc_coherent(dev, RX_RING_SZ + TX_RING_SZ,
+					 &priv->rxbd_dma, GFP_KERNEL);
+
+	if (!priv->rxbd) {
+		dev_err(dev, "failed to allocate data buffers\n");
+		err = -ENOMEM;
+		goto out_clken;
+	}
+
+	priv->txbd = priv->rxbd + RX_BD_NUM;
+
+	priv->txbd_dma = priv->rxbd_dma + RX_RING_SZ;
+	dev_dbg(dev, "EMAC Device addr: Rx Ring [0x%x], Tx Ring[%x]\n",
+		(unsigned int)priv->rxbd_dma, (unsigned int)priv->txbd_dma);
+
+	err = arc_mdio_probe(priv);
+	if (err) {
+		dev_err(dev, "failed to probe MII bus\n");
+		goto out_clken;
+	}
+
+	phydev = of_phy_connect(ndev, phy_node, arc_emac_adjust_link, 0,
+				interface);
+	if (!phydev) {
+		dev_err(dev, "of_phy_connect() failed\n");
+		err = -ENODEV;
+		goto out_mdio;
+	}
+
+	dev_info(dev, "connected to %s phy with id 0x%x\n",
+		 phydev->drv->name, phydev->phy_id);
+
+	netif_napi_add_weight(ndev, &priv->napi, arc_emac_poll,
+			      ARC_EMAC_NAPI_WEIGHT);
+
+	err = register_netdev(ndev);
+	if (err) {
+		dev_err(dev, "failed to register network device\n");
+		goto out_netif_api;
+	}
+
+	of_node_put(phy_node);
+	return 0;
+
+out_netif_api:
+	netif_napi_del(&priv->napi);
+	phy_disconnect(phydev);
+out_mdio:
+	arc_mdio_remove(priv);
+out_clken:
+	if (priv->clk)
+		clk_disable_unprepare(priv->clk);
+out_put_node:
+	of_node_put(phy_node);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(arc_emac_probe);
+
+int arc_emac_remove(struct net_device *ndev)
+{
+	struct arc_emac_priv *priv = netdev_priv(ndev);
+
+	phy_disconnect(ndev->phydev);
+	arc_mdio_remove(priv);
+	unregister_netdev(ndev);
+	netif_napi_del(&priv->napi);
+
+	if (!IS_ERR(priv->clk))
+		clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(arc_emac_remove);
+
+MODULE_AUTHOR("Alexey Brodkin <abrodkin@synopsys.com>");
+MODULE_DESCRIPTION("ARC EMAC driver");
+MODULE_LICENSE("GPL");