// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Actions Semi Owl SoCs Ethernet MAC driver
 *
 * Copyright (c) 2012 Actions Semi Inc.
 * Copyright (c) 2021 Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
 */

#include <linux/circ_buf.h>
#include <linux/clk.h>
#include <linux/dma-mapping.h>
#include <linux/etherdevice.h>
#include <linux/of_mdio.h>
#include <linux/of_net.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/reset.h>

#include "owl-emac.h"

#define OWL_EMAC_DEFAULT_MSG_ENABLE     (NETIF_MSG_DRV | \
                                         NETIF_MSG_PROBE | \
                                         NETIF_MSG_LINK)

static u32 owl_emac_reg_read(struct owl_emac_priv *priv, u32 reg)
{
        return readl(priv->base + reg);
}

static void owl_emac_reg_write(struct owl_emac_priv *priv, u32 reg, u32 data)
{
        writel(data, priv->base + reg);
}

static u32 owl_emac_reg_update(struct owl_emac_priv *priv,
                               u32 reg, u32 mask, u32 val)
{
        u32 data, old_val;

        data = owl_emac_reg_read(priv, reg);
        old_val = data & mask;

        data &= ~mask;
        data |= val & mask;

        owl_emac_reg_write(priv, reg, data);

        return old_val;
}

static void owl_emac_reg_set(struct owl_emac_priv *priv, u32 reg, u32 bits)
{
        owl_emac_reg_update(priv, reg, bits, bits);
}

static void owl_emac_reg_clear(struct owl_emac_priv *priv, u32 reg, u32 bits)
{
        owl_emac_reg_update(priv, reg, bits, 0);
}

static struct device *owl_emac_get_dev(struct owl_emac_priv *priv)
{
        return priv->netdev->dev.parent;
}

static void owl_emac_irq_enable(struct owl_emac_priv *priv)
{
        /* Enable all interrupts except TU.
         *
         * Note the NIE and AIE bits shall also be set in order to actually
         * enable the selected interrupts.
         */
        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR7,
                           OWL_EMAC_BIT_MAC_CSR7_NIE |
                           OWL_EMAC_BIT_MAC_CSR7_AIE |
                           OWL_EMAC_BIT_MAC_CSR7_ALL_NOT_TUE);
}

static void owl_emac_irq_disable(struct owl_emac_priv *priv)
{
        /* Disable all interrupts.
         *
         * WARNING: Unset only the NIE and AIE bits in CSR7 to workaround an
         * unexpected side effect (MAC hardware bug?!) where some bits in the
         * status register (CSR5) are cleared automatically before being able
         * to read them via owl_emac_irq_clear().
         */
        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR7,
                           OWL_EMAC_BIT_MAC_CSR7_ALL_NOT_TUE);
}

static u32 owl_emac_irq_status(struct owl_emac_priv *priv)
{
        return owl_emac_reg_read(priv, OWL_EMAC_REG_MAC_CSR5);
}

static u32 owl_emac_irq_clear(struct owl_emac_priv *priv)
{
        u32 val = owl_emac_irq_status(priv);

        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR5, val);

        return val;
}

static dma_addr_t owl_emac_dma_map_rx(struct owl_emac_priv *priv,
                                      struct sk_buff *skb)
{
        struct device *dev = owl_emac_get_dev(priv);

        /* Buffer pointer for the RX DMA descriptor must be word aligned. */
        return dma_map_single(dev, skb_tail_pointer(skb),
                              skb_tailroom(skb), DMA_FROM_DEVICE);
}

static void owl_emac_dma_unmap_rx(struct owl_emac_priv *priv,
                                  struct sk_buff *skb, dma_addr_t dma_addr)
{
        struct device *dev = owl_emac_get_dev(priv);

        dma_unmap_single(dev, dma_addr, skb_tailroom(skb), DMA_FROM_DEVICE);
}

static dma_addr_t owl_emac_dma_map_tx(struct owl_emac_priv *priv,
                                      struct sk_buff *skb)
{
        struct device *dev = owl_emac_get_dev(priv);

        return dma_map_single(dev, skb->data, skb_headlen(skb), DMA_TO_DEVICE);
}

static void owl_emac_dma_unmap_tx(struct owl_emac_priv *priv,
                                  struct sk_buff *skb, dma_addr_t dma_addr)
{
        struct device *dev = owl_emac_get_dev(priv);

        dma_unmap_single(dev, dma_addr, skb_headlen(skb), DMA_TO_DEVICE);
}

static unsigned int owl_emac_ring_num_unused(struct owl_emac_ring *ring)
{
        return CIRC_SPACE(ring->head, ring->tail, ring->size);
}

static unsigned int owl_emac_ring_get_next(struct owl_emac_ring *ring,
                                           unsigned int cur)
{
        return (cur + 1) & (ring->size - 1);
}

static void owl_emac_ring_push_head(struct owl_emac_ring *ring)
{
        ring->head = owl_emac_ring_get_next(ring, ring->head);
}

static void owl_emac_ring_pop_tail(struct owl_emac_ring *ring)
{
        ring->tail = owl_emac_ring_get_next(ring, ring->tail);
}

static struct sk_buff *owl_emac_alloc_skb(struct net_device *netdev)
{
        struct sk_buff *skb;
        int offset;

        skb = netdev_alloc_skb(netdev, OWL_EMAC_RX_FRAME_MAX_LEN +
                               OWL_EMAC_SKB_RESERVE);
        if (unlikely(!skb))
                return NULL;

        /* Ensure 4 bytes DMA alignment. */
        offset = ((uintptr_t)skb->data) & (OWL_EMAC_SKB_ALIGN - 1);
        if (unlikely(offset))
                skb_reserve(skb, OWL_EMAC_SKB_ALIGN - offset);

        return skb;
}

static int owl_emac_ring_prepare_rx(struct owl_emac_priv *priv)
{
        struct owl_emac_ring *ring = &priv->rx_ring;
        struct device *dev = owl_emac_get_dev(priv);
        struct net_device *netdev = priv->netdev;
        struct owl_emac_ring_desc *desc;
        struct sk_buff *skb;
        dma_addr_t dma_addr;
        int i;

        for (i = 0; i < ring->size; i++) {
                skb = owl_emac_alloc_skb(netdev);
                if (!skb)
                        return -ENOMEM;

                dma_addr = owl_emac_dma_map_rx(priv, skb);
                if (dma_mapping_error(dev, dma_addr)) {
                        dev_kfree_skb(skb);
                        return -ENOMEM;
                }

                desc = &ring->descs[i];
                desc->status = OWL_EMAC_BIT_RDES0_OWN;
                desc->control = skb_tailroom(skb) & OWL_EMAC_MSK_RDES1_RBS1;
                desc->buf_addr = dma_addr;
                desc->reserved = 0;

                ring->skbs[i] = skb;
                ring->skbs_dma[i] = dma_addr;
        }

        desc->control |= OWL_EMAC_BIT_RDES1_RER;

        ring->head = 0;
        ring->tail = 0;

        return 0;
}

static void owl_emac_ring_prepare_tx(struct owl_emac_priv *priv)
{
        struct owl_emac_ring *ring = &priv->tx_ring;
        struct owl_emac_ring_desc *desc;
        int i;

        for (i = 0; i < ring->size; i++) {
                desc = &ring->descs[i];

                desc->status = 0;
                desc->control = OWL_EMAC_BIT_TDES1_IC;
                desc->buf_addr = 0;
                desc->reserved = 0;
        }

        desc->control |= OWL_EMAC_BIT_TDES1_TER;

        memset(ring->skbs_dma, 0, sizeof(dma_addr_t) * ring->size);

        ring->head = 0;
        ring->tail = 0;
}

static void owl_emac_ring_unprepare_rx(struct owl_emac_priv *priv)
{
        struct owl_emac_ring *ring = &priv->rx_ring;
        int i;

        for (i = 0; i < ring->size; i++) {
                ring->descs[i].status = 0;

                if (!ring->skbs_dma[i])
                        continue;

                owl_emac_dma_unmap_rx(priv, ring->skbs[i], ring->skbs_dma[i]);
                ring->skbs_dma[i] = 0;

                dev_kfree_skb(ring->skbs[i]);
                ring->skbs[i] = NULL;
        }
}

static void owl_emac_ring_unprepare_tx(struct owl_emac_priv *priv)
{
        struct owl_emac_ring *ring = &priv->tx_ring;
        int i;

        for (i = 0; i < ring->size; i++) {
                ring->descs[i].status = 0;

                if (!ring->skbs_dma[i])
                        continue;

                owl_emac_dma_unmap_tx(priv, ring->skbs[i], ring->skbs_dma[i]);
                ring->skbs_dma[i] = 0;

                dev_kfree_skb(ring->skbs[i]);
                ring->skbs[i] = NULL;
        }
}

static int owl_emac_ring_alloc(struct device *dev, struct owl_emac_ring *ring,
                               unsigned int size)
{
        ring->descs = dmam_alloc_coherent(dev,
                                          sizeof(struct owl_emac_ring_desc) * size,
                                          &ring->descs_dma, GFP_KERNEL);
        if (!ring->descs)
                return -ENOMEM;

        ring->skbs = devm_kcalloc(dev, size, sizeof(struct sk_buff *),
                                  GFP_KERNEL);
        if (!ring->skbs)
                return -ENOMEM;

        ring->skbs_dma = devm_kcalloc(dev, size, sizeof(dma_addr_t),
                                      GFP_KERNEL);
        if (!ring->skbs_dma)
                return -ENOMEM;

        ring->size = size;

        return 0;
}

static void owl_emac_dma_cmd_resume_rx(struct owl_emac_priv *priv)
{
        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR2,
                           OWL_EMAC_VAL_MAC_CSR2_RPD);
}

static void owl_emac_dma_cmd_resume_tx(struct owl_emac_priv *priv)
{
        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR1,
                           OWL_EMAC_VAL_MAC_CSR1_TPD);
}

static u32 owl_emac_dma_cmd_set_tx(struct owl_emac_priv *priv, u32 status)
{
        return owl_emac_reg_update(priv, OWL_EMAC_REG_MAC_CSR6,
                                   OWL_EMAC_BIT_MAC_CSR6_ST, status);
}

static u32 owl_emac_dma_cmd_start_tx(struct owl_emac_priv *priv)
{
        return owl_emac_dma_cmd_set_tx(priv, ~0);
}

static u32 owl_emac_dma_cmd_set(struct owl_emac_priv *priv, u32 status)
{
        return owl_emac_reg_update(priv, OWL_EMAC_REG_MAC_CSR6,
                                   OWL_EMAC_MSK_MAC_CSR6_STSR, status);
}

static u32 owl_emac_dma_cmd_start(struct owl_emac_priv *priv)
{
        return owl_emac_dma_cmd_set(priv, ~0);
}

static u32 owl_emac_dma_cmd_stop(struct owl_emac_priv *priv)
{
        return owl_emac_dma_cmd_set(priv, 0);
}

static void owl_emac_set_hw_mac_addr(struct net_device *netdev)
{
        struct owl_emac_priv *priv = netdev_priv(netdev);
        const u8 *mac_addr = netdev->dev_addr;
        u32 addr_high, addr_low;

        addr_high = mac_addr[0] << 8 | mac_addr[1];
        addr_low = mac_addr[2] << 24 | mac_addr[3] << 16 |
                   mac_addr[4] << 8 | mac_addr[5];

        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR17, addr_high);
        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR16, addr_low);
}

static void owl_emac_update_link_state(struct owl_emac_priv *priv)
{
        u32 val, status;

        if (priv->pause) {
                val = OWL_EMAC_BIT_MAC_CSR20_FCE | OWL_EMAC_BIT_MAC_CSR20_TUE;
                val |= OWL_EMAC_BIT_MAC_CSR20_TPE | OWL_EMAC_BIT_MAC_CSR20_RPE;
                val |= OWL_EMAC_BIT_MAC_CSR20_BPE;
        } else {
                val = 0;
        }

        /* Update flow control. */
        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR20, val);

        val = (priv->speed == SPEED_100) ? OWL_EMAC_VAL_MAC_CSR6_SPEED_100M :
                                           OWL_EMAC_VAL_MAC_CSR6_SPEED_10M;
        val <<= OWL_EMAC_OFF_MAC_CSR6_SPEED;

        if (priv->duplex == DUPLEX_FULL)
                val |= OWL_EMAC_BIT_MAC_CSR6_FD;

        spin_lock_bh(&priv->lock);

        /* Temporarily stop DMA TX & RX. */
        status = owl_emac_dma_cmd_stop(priv);

        /* Update operation modes. */
        owl_emac_reg_update(priv, OWL_EMAC_REG_MAC_CSR6,
                            OWL_EMAC_MSK_MAC_CSR6_SPEED |
                            OWL_EMAC_BIT_MAC_CSR6_FD, val);

        /* Restore DMA TX & RX status. */
        owl_emac_dma_cmd_set(priv, status);

        spin_unlock_bh(&priv->lock);
}

static void owl_emac_adjust_link(struct net_device *netdev)
{
        struct owl_emac_priv *priv = netdev_priv(netdev);
        struct phy_device *phydev = netdev->phydev;
        bool state_changed = false;

        if (phydev->link) {
                if (!priv->link) {
                        priv->link = phydev->link;
                        state_changed = true;
                }

                if (priv->speed != phydev->speed) {
                        priv->speed = phydev->speed;
                        state_changed = true;
                }

                if (priv->duplex != phydev->duplex) {
                        priv->duplex = phydev->duplex;
                        state_changed = true;
                }

                if (priv->pause != phydev->pause) {
                        priv->pause = phydev->pause;
                        state_changed = true;
                }
        } else {
                if (priv->link) {
                        priv->link = phydev->link;
                        state_changed = true;
                }
        }

        if (state_changed) {
                if (phydev->link)
                        owl_emac_update_link_state(priv);

                if (netif_msg_link(priv))
                        phy_print_status(phydev);
        }
}

static irqreturn_t owl_emac_handle_irq(int irq, void *data)
{
        struct net_device *netdev = data;
        struct owl_emac_priv *priv = netdev_priv(netdev);

        if (netif_running(netdev)) {
                owl_emac_irq_disable(priv);
                napi_schedule(&priv->napi);
        }

        return IRQ_HANDLED;
}

static void owl_emac_ether_addr_push(u8 **dst, const u8 *src)
{
        u32 *a = (u32 *)(*dst);
        const u16 *b = (const u16 *)src;

        a[0] = b[0];
        a[1] = b[1];
        a[2] = b[2];

        *dst += 12;
}

static void
owl_emac_setup_frame_prepare(struct owl_emac_priv *priv, struct sk_buff *skb)
{
        const u8 bcast_addr[] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
        const u8 *mac_addr = priv->netdev->dev_addr;
        u8 *frame;
        int i;

        skb_put(skb, OWL_EMAC_SETUP_FRAME_LEN);

        frame = skb->data;
        memset(frame, 0, skb->len);

        owl_emac_ether_addr_push(&frame, mac_addr);
        owl_emac_ether_addr_push(&frame, bcast_addr);

        /* Fill multicast addresses. */
        WARN_ON(priv->mcaddr_list.count >= OWL_EMAC_MAX_MULTICAST_ADDRS);
        for (i = 0; i < priv->mcaddr_list.count; i++) {
                mac_addr = priv->mcaddr_list.addrs[i];
                owl_emac_ether_addr_push(&frame, mac_addr);
        }
}

/* The setup frame is a special descriptor which is used to provide physical
 * addresses (i.e. mac, broadcast and multicast) to the MAC hardware for
 * filtering purposes. To be recognized as a setup frame, the TDES1_SET bit
 * must be set in the TX descriptor control field.
 */
static int owl_emac_setup_frame_xmit(struct owl_emac_priv *priv)
{
        struct owl_emac_ring *ring = &priv->tx_ring;
        struct net_device *netdev = priv->netdev;
        struct owl_emac_ring_desc *desc;
        struct sk_buff *skb;
        unsigned int tx_head;
        u32 status, control;
        dma_addr_t dma_addr;
        int ret;

        skb = owl_emac_alloc_skb(netdev);
        if (!skb)
                return -ENOMEM;

        owl_emac_setup_frame_prepare(priv, skb);

        dma_addr = owl_emac_dma_map_tx(priv, skb);
        if (dma_mapping_error(owl_emac_get_dev(priv), dma_addr)) {
                ret = -ENOMEM;
                goto err_free_skb;
        }

        spin_lock_bh(&priv->lock);

        tx_head = ring->head;
        desc = &ring->descs[tx_head];

        status = READ_ONCE(desc->status);
        control = READ_ONCE(desc->control);
        dma_rmb(); /* Ensure data has been read before used. */

        if (unlikely(status & OWL_EMAC_BIT_TDES0_OWN) ||
            !owl_emac_ring_num_unused(ring)) {
                spin_unlock_bh(&priv->lock);
                owl_emac_dma_unmap_tx(priv, skb, dma_addr);
                ret = -EBUSY;
                goto err_free_skb;
        }

        ring->skbs[tx_head] = skb;
        ring->skbs_dma[tx_head] = dma_addr;

        control &= OWL_EMAC_BIT_TDES1_IC | OWL_EMAC_BIT_TDES1_TER; /* Maintain bits */
        control |= OWL_EMAC_BIT_TDES1_SET;
        control |= OWL_EMAC_MSK_TDES1_TBS1 & skb->len;

        WRITE_ONCE(desc->control, control);
        WRITE_ONCE(desc->buf_addr, dma_addr);
        dma_wmb(); /* Flush descriptor before changing ownership. */
        WRITE_ONCE(desc->status, OWL_EMAC_BIT_TDES0_OWN);

        owl_emac_ring_push_head(ring);

        /* Temporarily enable DMA TX. */
        status = owl_emac_dma_cmd_start_tx(priv);

        /* Trigger setup frame processing. */
        owl_emac_dma_cmd_resume_tx(priv);

        /* Restore DMA TX status. */
        owl_emac_dma_cmd_set_tx(priv, status);

        /* Stop regular TX until setup frame is processed. */
        netif_stop_queue(netdev);

        spin_unlock_bh(&priv->lock);

        return 0;

err_free_skb:
        dev_kfree_skb(skb);
        return ret;
}

static netdev_tx_t owl_emac_ndo_start_xmit(struct sk_buff *skb,
                                           struct net_device *netdev)
{
        struct owl_emac_priv *priv = netdev_priv(netdev);
        struct device *dev = owl_emac_get_dev(priv);
        struct owl_emac_ring *ring = &priv->tx_ring;
        struct owl_emac_ring_desc *desc;
        unsigned int tx_head;
        u32 status, control;
        dma_addr_t dma_addr;

        dma_addr = owl_emac_dma_map_tx(priv, skb);
        if (dma_mapping_error(dev, dma_addr)) {
                dev_err_ratelimited(&netdev->dev, "TX DMA mapping failed\n");
                dev_kfree_skb(skb);
                netdev->stats.tx_dropped++;
                return NETDEV_TX_OK;
        }

        spin_lock_bh(&priv->lock);

        tx_head = ring->head;
        desc = &ring->descs[tx_head];

        status = READ_ONCE(desc->status);
        control = READ_ONCE(desc->control);
        dma_rmb(); /* Ensure data has been read before used. */

        if (!owl_emac_ring_num_unused(ring) ||
            unlikely(status & OWL_EMAC_BIT_TDES0_OWN)) {
                netif_stop_queue(netdev);
                spin_unlock_bh(&priv->lock);

                dev_dbg_ratelimited(&netdev->dev, "TX buffer full, status=0x%08x\n",
                                    owl_emac_irq_status(priv));
                owl_emac_dma_unmap_tx(priv, skb, dma_addr);
                netdev->stats.tx_dropped++;
                return NETDEV_TX_BUSY;
        }

        ring->skbs[tx_head] = skb;
        ring->skbs_dma[tx_head] = dma_addr;

        control &= OWL_EMAC_BIT_TDES1_IC | OWL_EMAC_BIT_TDES1_TER; /* Maintain bits */
        control |= OWL_EMAC_BIT_TDES1_FS | OWL_EMAC_BIT_TDES1_LS;
        control |= OWL_EMAC_MSK_TDES1_TBS1 & skb->len;

        WRITE_ONCE(desc->control, control);
        WRITE_ONCE(desc->buf_addr, dma_addr);
        dma_wmb(); /* Flush descriptor before changing ownership. */
        WRITE_ONCE(desc->status, OWL_EMAC_BIT_TDES0_OWN);

        owl_emac_dma_cmd_resume_tx(priv);
        owl_emac_ring_push_head(ring);

        /* FIXME: The transmission is currently restricted to a single frame
         * at a time as a workaround for a MAC hardware bug that causes random
         * freeze of the TX queue processor.
         */
        netif_stop_queue(netdev);

        spin_unlock_bh(&priv->lock);

        return NETDEV_TX_OK;
}

static bool owl_emac_tx_complete_tail(struct owl_emac_priv *priv)
{
        struct owl_emac_ring *ring = &priv->tx_ring;
        struct net_device *netdev = priv->netdev;
        struct owl_emac_ring_desc *desc;
        struct sk_buff *skb;
        unsigned int tx_tail;
        u32 status;

        tx_tail = ring->tail;
        desc = &ring->descs[tx_tail];

        status = READ_ONCE(desc->status);
        dma_rmb(); /* Ensure data has been read before used. */

        if (status & OWL_EMAC_BIT_TDES0_OWN)
                return false;

        /* Check for errors. */
        if (status & OWL_EMAC_BIT_TDES0_ES) {
                dev_dbg_ratelimited(&netdev->dev,
                                    "TX complete error status: 0x%08x\n",
                                    status);

                netdev->stats.tx_errors++;

                if (status & OWL_EMAC_BIT_TDES0_UF)
                        netdev->stats.tx_fifo_errors++;

                if (status & OWL_EMAC_BIT_TDES0_EC)
                        netdev->stats.tx_aborted_errors++;

                if (status & OWL_EMAC_BIT_TDES0_LC)
                        netdev->stats.tx_window_errors++;

                if (status & OWL_EMAC_BIT_TDES0_NC)
                        netdev->stats.tx_heartbeat_errors++;

                if (status & OWL_EMAC_BIT_TDES0_LO)
                        netdev->stats.tx_carrier_errors++;
        } else {
                netdev->stats.tx_packets++;
                netdev->stats.tx_bytes += ring->skbs[tx_tail]->len;
        }

        /* Some collisions occurred, but pkt has been transmitted. */
        if (status & OWL_EMAC_BIT_TDES0_DE)
                netdev->stats.collisions++;

        skb = ring->skbs[tx_tail];
        owl_emac_dma_unmap_tx(priv, skb, ring->skbs_dma[tx_tail]);
        dev_kfree_skb(skb);

        ring->skbs[tx_tail] = NULL;
        ring->skbs_dma[tx_tail] = 0;

        owl_emac_ring_pop_tail(ring);

        if (unlikely(netif_queue_stopped(netdev)))
                netif_wake_queue(netdev);

        return true;
}

static void owl_emac_tx_complete(struct owl_emac_priv *priv)
{
        struct owl_emac_ring *ring = &priv->tx_ring;
        struct net_device *netdev = priv->netdev;
        unsigned int tx_next;
        u32 status;

        spin_lock(&priv->lock);

        while (ring->tail != ring->head) {
                if (!owl_emac_tx_complete_tail(priv))
                        break;
        }

        /* FIXME: This is a workaround for a MAC hardware bug not clearing
         * (sometimes) the OWN bit for a transmitted frame descriptor.
         *
         * At this point, when TX queue is full, the tail descriptor has the
         * OWN bit set, which normally means the frame has not been processed
         * or transmitted yet. But if there is at least one descriptor in the
         * queue having the OWN bit cleared, we can safely assume the tail
         * frame has been also processed by the MAC hardware.
         *
         * If that's the case, let's force the frame completion by manually
         * clearing the OWN bit.
         */
        if (unlikely(!owl_emac_ring_num_unused(ring))) {
                tx_next = ring->tail;

                while ((tx_next = owl_emac_ring_get_next(ring, tx_next)) != ring->head) {
                        status = READ_ONCE(ring->descs[tx_next].status);
                        dma_rmb(); /* Ensure data has been read before used. */

                        if (status & OWL_EMAC_BIT_TDES0_OWN)
                                continue;

                        netdev_dbg(netdev, "Found uncleared TX desc OWN bit\n");

                        status = READ_ONCE(ring->descs[ring->tail].status);
                        dma_rmb(); /* Ensure data has been read before used. */
                        status &= ~OWL_EMAC_BIT_TDES0_OWN;
                        WRITE_ONCE(ring->descs[ring->tail].status, status);

                        owl_emac_tx_complete_tail(priv);
                        break;
                }
        }

        spin_unlock(&priv->lock);
}

static int owl_emac_rx_process(struct owl_emac_priv *priv, int budget)
{
        struct owl_emac_ring *ring = &priv->rx_ring;
        struct device *dev = owl_emac_get_dev(priv);
        struct net_device *netdev = priv->netdev;
        struct owl_emac_ring_desc *desc;
        struct sk_buff *curr_skb, *new_skb;
        dma_addr_t curr_dma, new_dma;
        unsigned int rx_tail, len;
        u32 status;
        int recv = 0;

        while (recv < budget) {
                spin_lock(&priv->lock);

                rx_tail = ring->tail;
                desc = &ring->descs[rx_tail];

                status = READ_ONCE(desc->status);
                dma_rmb(); /* Ensure data has been read before used. */

                if (status & OWL_EMAC_BIT_RDES0_OWN) {
                        spin_unlock(&priv->lock);
                        break;
                }

                curr_skb = ring->skbs[rx_tail];
                curr_dma = ring->skbs_dma[rx_tail];
                owl_emac_ring_pop_tail(ring);

                spin_unlock(&priv->lock);

                if (status & (OWL_EMAC_BIT_RDES0_DE | OWL_EMAC_BIT_RDES0_RF |
                    OWL_EMAC_BIT_RDES0_TL | OWL_EMAC_BIT_RDES0_CS |
                    OWL_EMAC_BIT_RDES0_DB | OWL_EMAC_BIT_RDES0_CE |
                    OWL_EMAC_BIT_RDES0_ZERO)) {
                        dev_dbg_ratelimited(&netdev->dev,
                                            "RX desc error status: 0x%08x\n",
                                            status);

                        if (status & OWL_EMAC_BIT_RDES0_DE)
                                netdev->stats.rx_over_errors++;

                        if (status & (OWL_EMAC_BIT_RDES0_RF | OWL_EMAC_BIT_RDES0_DB))
                                netdev->stats.rx_frame_errors++;

                        if (status & OWL_EMAC_BIT_RDES0_TL)
                                netdev->stats.rx_length_errors++;

                        if (status & OWL_EMAC_BIT_RDES0_CS)
                                netdev->stats.collisions++;

                        if (status & OWL_EMAC_BIT_RDES0_CE)
                                netdev->stats.rx_crc_errors++;

                        if (status & OWL_EMAC_BIT_RDES0_ZERO)
                                netdev->stats.rx_fifo_errors++;

                        goto drop_skb;
                }

                len = (status & OWL_EMAC_MSK_RDES0_FL) >> OWL_EMAC_OFF_RDES0_FL;
                if (unlikely(len > OWL_EMAC_RX_FRAME_MAX_LEN)) {
                        netdev->stats.rx_length_errors++;
                        netdev_err(netdev, "invalid RX frame len: %u\n", len);
                        goto drop_skb;
                }

                /* Prepare new skb before receiving the current one. */
                new_skb = owl_emac_alloc_skb(netdev);
                if (unlikely(!new_skb))
                        goto drop_skb;

                new_dma = owl_emac_dma_map_rx(priv, new_skb);
                if (dma_mapping_error(dev, new_dma)) {
                        dev_kfree_skb(new_skb);
                        netdev_err(netdev, "RX DMA mapping failed\n");
                        goto drop_skb;
                }

                owl_emac_dma_unmap_rx(priv, curr_skb, curr_dma);

                skb_put(curr_skb, len - ETH_FCS_LEN);
                curr_skb->ip_summed = CHECKSUM_NONE;
                curr_skb->protocol = eth_type_trans(curr_skb, netdev);
                curr_skb->dev = netdev;

                netif_receive_skb(curr_skb);

                netdev->stats.rx_packets++;
                netdev->stats.rx_bytes += len;
                recv++;
                goto push_skb;

drop_skb:
                netdev->stats.rx_dropped++;
                netdev->stats.rx_errors++;
                /* Reuse the current skb. */
                new_skb = curr_skb;
                new_dma = curr_dma;

push_skb:
                spin_lock(&priv->lock);

                ring->skbs[ring->head] = new_skb;
                ring->skbs_dma[ring->head] = new_dma;

                WRITE_ONCE(desc->buf_addr, new_dma);
                dma_wmb(); /* Flush descriptor before changing ownership. */
                WRITE_ONCE(desc->status, OWL_EMAC_BIT_RDES0_OWN);

                owl_emac_ring_push_head(ring);

                spin_unlock(&priv->lock);
        }

        return recv;
}

static int owl_emac_poll(struct napi_struct *napi, int budget)
{
        int work_done = 0, ru_cnt = 0, recv;
        static int tx_err_cnt, rx_err_cnt;
        struct owl_emac_priv *priv;
        u32 status, proc_status;

        priv = container_of(napi, struct owl_emac_priv, napi);

        while ((status = owl_emac_irq_clear(priv)) &
               (OWL_EMAC_BIT_MAC_CSR5_NIS | OWL_EMAC_BIT_MAC_CSR5_AIS)) {
                recv = 0;

                /* TX setup frame raises ETI instead of TI. */
                if (status & (OWL_EMAC_BIT_MAC_CSR5_TI | OWL_EMAC_BIT_MAC_CSR5_ETI)) {
                        owl_emac_tx_complete(priv);
                        tx_err_cnt = 0;

                        /* Count MAC internal RX errors. */
                        proc_status = status & OWL_EMAC_MSK_MAC_CSR5_RS;
                        proc_status >>= OWL_EMAC_OFF_MAC_CSR5_RS;
                        if (proc_status == OWL_EMAC_VAL_MAC_CSR5_RS_DATA ||
                            proc_status == OWL_EMAC_VAL_MAC_CSR5_RS_CDES ||
                            proc_status == OWL_EMAC_VAL_MAC_CSR5_RS_FDES)
                                rx_err_cnt++;
                }

                if (status & OWL_EMAC_BIT_MAC_CSR5_RI) {
                        recv = owl_emac_rx_process(priv, budget - work_done);
                        rx_err_cnt = 0;

                        /* Count MAC internal TX errors. */
                        proc_status = status & OWL_EMAC_MSK_MAC_CSR5_TS;
                        proc_status >>= OWL_EMAC_OFF_MAC_CSR5_TS;
                        if (proc_status == OWL_EMAC_VAL_MAC_CSR5_TS_DATA ||
                            proc_status == OWL_EMAC_VAL_MAC_CSR5_TS_CDES)
                                tx_err_cnt++;
                } else if (status & OWL_EMAC_BIT_MAC_CSR5_RU) {
                        /* MAC AHB is in suspended state, will return to RX
                         * descriptor processing when the host changes ownership
                         * of the descriptor and either an RX poll demand CMD is
                         * issued or a new frame is recognized by the MAC AHB.
                         */
                        if (++ru_cnt == 2)
                                owl_emac_dma_cmd_resume_rx(priv);

                        recv = owl_emac_rx_process(priv, budget - work_done);

                        /* Guard against too many RU interrupts. */
                        if (ru_cnt > 3)
                                break;
                }

                work_done += recv;
                if (work_done >= budget)
                        break;
        }

        if (work_done < budget) {
                napi_complete_done(napi, work_done);
                owl_emac_irq_enable(priv);
        }

        /* Reset MAC when getting too many internal TX or RX errors. */
        if (tx_err_cnt > 10 || rx_err_cnt > 10) {
                netdev_dbg(priv->netdev, "%s error status: 0x%08x\n",
                           tx_err_cnt > 10 ? "TX" : "RX", status);
                rx_err_cnt = 0;
                tx_err_cnt = 0;
                schedule_work(&priv->mac_reset_task);
        }

        return work_done;
}

static void owl_emac_mdio_clock_enable(struct owl_emac_priv *priv)
{
        u32 val;

        /* Enable MDC clock generation by adjusting CLKDIV according to
         * the vendor implementation of the original driver.
         */
        val = owl_emac_reg_read(priv, OWL_EMAC_REG_MAC_CSR10);
        val &= OWL_EMAC_MSK_MAC_CSR10_CLKDIV;
        val |= OWL_EMAC_VAL_MAC_CSR10_CLKDIV_128 << OWL_EMAC_OFF_MAC_CSR10_CLKDIV;

        val |= OWL_EMAC_BIT_MAC_CSR10_SB;
        val |= OWL_EMAC_VAL_MAC_CSR10_OPCODE_CDS << OWL_EMAC_OFF_MAC_CSR10_OPCODE;
        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR10, val);
}

static void owl_emac_core_hw_reset(struct owl_emac_priv *priv)
{
        /* Trigger hardware reset. */
        reset_control_assert(priv->reset);
        usleep_range(10, 20);
        reset_control_deassert(priv->reset);
        usleep_range(100, 200);
}

static int owl_emac_core_sw_reset(struct owl_emac_priv *priv)
{
        u32 val;
        int ret;

        /* Trigger software reset. */
        owl_emac_reg_set(priv, OWL_EMAC_REG_MAC_CSR0, OWL_EMAC_BIT_MAC_CSR0_SWR);
        ret = readl_poll_timeout(priv->base + OWL_EMAC_REG_MAC_CSR0,
                                 val, !(val & OWL_EMAC_BIT_MAC_CSR0_SWR),
                                 OWL_EMAC_POLL_DELAY_USEC,
                                 OWL_EMAC_RESET_POLL_TIMEOUT_USEC);
        if (ret)
                return ret;

        if (priv->phy_mode == PHY_INTERFACE_MODE_RMII) {
                /* Enable RMII and use the 50MHz rmii clk as output to PHY. */
                val = 0;
        } else {
                /* Enable SMII and use the 125MHz rmii clk as output to PHY.
                 * Additionally set SMII SYNC delay to 4 half cycle.
                 */
                val = 0x04 << OWL_EMAC_OFF_MAC_CTRL_SSDC;
                val |= OWL_EMAC_BIT_MAC_CTRL_RSIS;
        }
        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CTRL, val);

        /* MDC is disabled after reset. */
        owl_emac_mdio_clock_enable(priv);

        /* Set FIFO pause & restart threshold levels. */
        val = 0x40 << OWL_EMAC_OFF_MAC_CSR19_FPTL;
        val |= 0x10 << OWL_EMAC_OFF_MAC_CSR19_FRTL;
        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR19, val);

        /* Set flow control pause quanta time to ~100 ms. */
        val = 0x4FFF << OWL_EMAC_OFF_MAC_CSR18_PQT;
        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR18, val);

        /* Setup interrupt mitigation. */
        val = 7 << OWL_EMAC_OFF_MAC_CSR11_NRP;
        val |= 4 << OWL_EMAC_OFF_MAC_CSR11_RT;
        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR11, val);

        /* Set RX/TX rings base addresses. */
        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR3,
                           (u32)(priv->rx_ring.descs_dma));
        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR4,
                           (u32)(priv->tx_ring.descs_dma));

        /* Setup initial operation mode. */
        val = OWL_EMAC_VAL_MAC_CSR6_SPEED_100M << OWL_EMAC_OFF_MAC_CSR6_SPEED;
        val |= OWL_EMAC_BIT_MAC_CSR6_FD;
        owl_emac_reg_update(priv, OWL_EMAC_REG_MAC_CSR6,
                            OWL_EMAC_MSK_MAC_CSR6_SPEED |
                            OWL_EMAC_BIT_MAC_CSR6_FD, val);
        owl_emac_reg_clear(priv, OWL_EMAC_REG_MAC_CSR6,
                           OWL_EMAC_BIT_MAC_CSR6_PR | OWL_EMAC_BIT_MAC_CSR6_PM);

        priv->link = 0;
        priv->speed = SPEED_UNKNOWN;
        priv->duplex = DUPLEX_UNKNOWN;
        priv->pause = 0;
        priv->mcaddr_list.count = 0;

        return 0;
}

static int owl_emac_enable(struct net_device *netdev, bool start_phy)
{
        struct owl_emac_priv *priv = netdev_priv(netdev);
        int ret;

        owl_emac_dma_cmd_stop(priv);
        owl_emac_irq_disable(priv);
        owl_emac_irq_clear(priv);

        owl_emac_ring_prepare_tx(priv);
        ret = owl_emac_ring_prepare_rx(priv);
        if (ret)
                goto err_unprep;

        ret = owl_emac_core_sw_reset(priv);
        if (ret) {
                netdev_err(netdev, "failed to soft reset MAC core: %d\n", ret);
                goto err_unprep;
        }

        owl_emac_set_hw_mac_addr(netdev);
        owl_emac_setup_frame_xmit(priv);

        netdev_reset_queue(netdev);
        napi_enable(&priv->napi);

        owl_emac_irq_enable(priv);
        owl_emac_dma_cmd_start(priv);

        if (start_phy)
                phy_start(netdev->phydev);

        netif_start_queue(netdev);

        return 0;

err_unprep:
        owl_emac_ring_unprepare_rx(priv);
        owl_emac_ring_unprepare_tx(priv);

        return ret;
}

static void owl_emac_disable(struct net_device *netdev, bool stop_phy)
{
        struct owl_emac_priv *priv = netdev_priv(netdev);

        owl_emac_dma_cmd_stop(priv);
        owl_emac_irq_disable(priv);

        netif_stop_queue(netdev);
        napi_disable(&priv->napi);

        if (stop_phy)
                phy_stop(netdev->phydev);

        owl_emac_ring_unprepare_rx(priv);
        owl_emac_ring_unprepare_tx(priv);
}

static int owl_emac_ndo_open(struct net_device *netdev)
{
        return owl_emac_enable(netdev, true);
}

static int owl_emac_ndo_stop(struct net_device *netdev)
{
        owl_emac_disable(netdev, true);

        return 0;
}

static void owl_emac_set_multicast(struct net_device *netdev, int count)
{
        struct owl_emac_priv *priv = netdev_priv(netdev);
        struct netdev_hw_addr *ha;
        int index = 0;

        if (count <= 0) {
                priv->mcaddr_list.count = 0;
                return;
        }

        netdev_for_each_mc_addr(ha, netdev) {
                if (!is_multicast_ether_addr(ha->addr))
                        continue;

                WARN_ON(index >= OWL_EMAC_MAX_MULTICAST_ADDRS);
                ether_addr_copy(priv->mcaddr_list.addrs[index++], ha->addr);
        }

        priv->mcaddr_list.count = index;

        owl_emac_setup_frame_xmit(priv);
}

static void owl_emac_ndo_set_rx_mode(struct net_device *netdev)
{
        struct owl_emac_priv *priv = netdev_priv(netdev);
        u32 status, val = 0;
        int mcast_count = 0;

        if (netdev->flags & IFF_PROMISC) {
                val = OWL_EMAC_BIT_MAC_CSR6_PR;
        } else if (netdev->flags & IFF_ALLMULTI) {
                val = OWL_EMAC_BIT_MAC_CSR6_PM;
        } else if (netdev->flags & IFF_MULTICAST) {
                mcast_count = netdev_mc_count(netdev);

                if (mcast_count > OWL_EMAC_MAX_MULTICAST_ADDRS) {
                        val = OWL_EMAC_BIT_MAC_CSR6_PM;
                        mcast_count = 0;
                }
        }

        spin_lock_bh(&priv->lock);

        /* Temporarily stop DMA TX & RX. */
        status = owl_emac_dma_cmd_stop(priv);

        /* Update operation modes. */
        owl_emac_reg_update(priv, OWL_EMAC_REG_MAC_CSR6,
                            OWL_EMAC_BIT_MAC_CSR6_PR | OWL_EMAC_BIT_MAC_CSR6_PM,
                            val);

        /* Restore DMA TX & RX status. */
        owl_emac_dma_cmd_set(priv, status);

        spin_unlock_bh(&priv->lock);

        /* Set/reset multicast addr list. */
        owl_emac_set_multicast(netdev, mcast_count);
}

static int owl_emac_ndo_set_mac_addr(struct net_device *netdev, void *addr)
{
        struct sockaddr *skaddr = addr;

        if (!is_valid_ether_addr(skaddr->sa_data))
                return -EADDRNOTAVAIL;

        if (netif_running(netdev))
                return -EBUSY;

        eth_hw_addr_set(netdev, skaddr->sa_data);
        owl_emac_set_hw_mac_addr(netdev);

        return owl_emac_setup_frame_xmit(netdev_priv(netdev));
}

static int owl_emac_ndo_eth_ioctl(struct net_device *netdev,
                                  struct ifreq *req, int cmd)
{
        if (!netif_running(netdev))
                return -EINVAL;

        return phy_mii_ioctl(netdev->phydev, req, cmd);
}

static void owl_emac_ndo_tx_timeout(struct net_device *netdev,
                                    unsigned int txqueue)
{
        struct owl_emac_priv *priv = netdev_priv(netdev);

        schedule_work(&priv->mac_reset_task);
}

static void owl_emac_reset_task(struct work_struct *work)
{
        struct owl_emac_priv *priv;

        priv = container_of(work, struct owl_emac_priv, mac_reset_task);

        netdev_dbg(priv->netdev, "resetting MAC\n");
        owl_emac_disable(priv->netdev, false);
        owl_emac_enable(priv->netdev, false);
}

static struct net_device_stats *
owl_emac_ndo_get_stats(struct net_device *netdev)
{
        /* FIXME: If possible, try to get stats from MAC hardware registers
         * instead of tracking them manually in the driver.
         */

        return &netdev->stats;
}

static const struct net_device_ops owl_emac_netdev_ops = {
        .ndo_open               = owl_emac_ndo_open,
        .ndo_stop               = owl_emac_ndo_stop,
        .ndo_start_xmit         = owl_emac_ndo_start_xmit,
        .ndo_set_rx_mode        = owl_emac_ndo_set_rx_mode,
        .ndo_set_mac_address    = owl_emac_ndo_set_mac_addr,
        .ndo_validate_addr      = eth_validate_addr,
        .ndo_eth_ioctl          = owl_emac_ndo_eth_ioctl,
        .ndo_tx_timeout         = owl_emac_ndo_tx_timeout,
        .ndo_get_stats          = owl_emac_ndo_get_stats,
};

static void owl_emac_ethtool_get_drvinfo(struct net_device *dev,
                                         struct ethtool_drvinfo *info)
{
        strscpy(info->driver, OWL_EMAC_DRVNAME, sizeof(info->driver));
}

static u32 owl_emac_ethtool_get_msglevel(struct net_device *netdev)
{
        struct owl_emac_priv *priv = netdev_priv(netdev);

        return priv->msg_enable;
}

static void owl_emac_ethtool_set_msglevel(struct net_device *ndev, u32 val)
{
        struct owl_emac_priv *priv = netdev_priv(ndev);

        priv->msg_enable = val;
}

static const struct ethtool_ops owl_emac_ethtool_ops = {
        .get_drvinfo            = owl_emac_ethtool_get_drvinfo,
        .get_link               = ethtool_op_get_link,
        .get_link_ksettings     = phy_ethtool_get_link_ksettings,
        .set_link_ksettings     = phy_ethtool_set_link_ksettings,
        .get_msglevel           = owl_emac_ethtool_get_msglevel,
        .set_msglevel           = owl_emac_ethtool_set_msglevel,
};

static int owl_emac_mdio_wait(struct owl_emac_priv *priv)
{
        u32 val;

        /* Wait while data transfer is in progress. */
        return readl_poll_timeout(priv->base + OWL_EMAC_REG_MAC_CSR10,
                                  val, !(val & OWL_EMAC_BIT_MAC_CSR10_SB),
                                  OWL_EMAC_POLL_DELAY_USEC,
                                  OWL_EMAC_MDIO_POLL_TIMEOUT_USEC);
}

static int owl_emac_mdio_read(struct mii_bus *bus, int addr, int regnum)
{
        struct owl_emac_priv *priv = bus->priv;
        u32 data, tmp;
        int ret;

        data = OWL_EMAC_BIT_MAC_CSR10_SB;
        data |= OWL_EMAC_VAL_MAC_CSR10_OPCODE_RD << OWL_EMAC_OFF_MAC_CSR10_OPCODE;

        tmp = addr << OWL_EMAC_OFF_MAC_CSR10_PHYADD;
        data |= tmp & OWL_EMAC_MSK_MAC_CSR10_PHYADD;

        tmp = regnum << OWL_EMAC_OFF_MAC_CSR10_REGADD;
        data |= tmp & OWL_EMAC_MSK_MAC_CSR10_REGADD;

        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR10, data);

        ret = owl_emac_mdio_wait(priv);
        if (ret)
                return ret;

        data = owl_emac_reg_read(priv, OWL_EMAC_REG_MAC_CSR10);
        data &= OWL_EMAC_MSK_MAC_CSR10_DATA;

        return data;
}

static int
owl_emac_mdio_write(struct mii_bus *bus, int addr, int regnum, u16 val)
{
        struct owl_emac_priv *priv = bus->priv;
        u32 data, tmp;

        data = OWL_EMAC_BIT_MAC_CSR10_SB;
        data |= OWL_EMAC_VAL_MAC_CSR10_OPCODE_WR << OWL_EMAC_OFF_MAC_CSR10_OPCODE;

        tmp = addr << OWL_EMAC_OFF_MAC_CSR10_PHYADD;
        data |= tmp & OWL_EMAC_MSK_MAC_CSR10_PHYADD;

        tmp = regnum << OWL_EMAC_OFF_MAC_CSR10_REGADD;
        data |= tmp & OWL_EMAC_MSK_MAC_CSR10_REGADD;

        data |= val & OWL_EMAC_MSK_MAC_CSR10_DATA;

        owl_emac_reg_write(priv, OWL_EMAC_REG_MAC_CSR10, data);

        return owl_emac_mdio_wait(priv);
}

static int owl_emac_mdio_init(struct net_device *netdev)
{
        struct owl_emac_priv *priv = netdev_priv(netdev);
        struct device *dev = owl_emac_get_dev(priv);
        struct device_node *mdio_node;
        int ret;

        mdio_node = of_get_available_child_by_name(dev->of_node, "mdio");
        if (!mdio_node)
                return -ENODEV;

        priv->mii = devm_mdiobus_alloc(dev);
        if (!priv->mii) {
                ret = -ENOMEM;
                goto err_put_node;
        }

        snprintf(priv->mii->id, MII_BUS_ID_SIZE, "%s", dev_name(dev));
        priv->mii->name = "owl-emac-mdio";
        priv->mii->parent = dev;
        priv->mii->read = owl_emac_mdio_read;
        priv->mii->write = owl_emac_mdio_write;
        priv->mii->phy_mask = ~0; /* Mask out all PHYs from auto probing. */
        priv->mii->priv = priv;

        ret = devm_of_mdiobus_register(dev, priv->mii, mdio_node);

err_put_node:
        of_node_put(mdio_node);
        return ret;
}

static int owl_emac_phy_init(struct net_device *netdev)
{
        struct owl_emac_priv *priv = netdev_priv(netdev);
        struct device *dev = owl_emac_get_dev(priv);
        struct phy_device *phy;

        phy = of_phy_get_and_connect(netdev, dev->of_node,
                                     owl_emac_adjust_link);
        if (!phy)
                return -ENODEV;

        phy_set_sym_pause(phy, true, true, true);

        if (netif_msg_link(priv))
                phy_attached_info(phy);

        return 0;
}

static void owl_emac_get_mac_addr(struct net_device *netdev)
{
        struct device *dev = netdev->dev.parent;
        int ret;

        ret = platform_get_ethdev_address(dev, netdev);
        if (!ret && is_valid_ether_addr(netdev->dev_addr))
                return;

        eth_hw_addr_random(netdev);
        dev_warn(dev, "using random MAC address %pM\n", netdev->dev_addr);
}

static __maybe_unused int owl_emac_suspend(struct device *dev)
{
        struct net_device *netdev = dev_get_drvdata(dev);
        struct owl_emac_priv *priv = netdev_priv(netdev);

        disable_irq(netdev->irq);

        if (netif_running(netdev)) {
                owl_emac_disable(netdev, true);
                netif_device_detach(netdev);
        }

        clk_bulk_disable_unprepare(OWL_EMAC_NCLKS, priv->clks);

        return 0;
}

static __maybe_unused int owl_emac_resume(struct device *dev)
{
        struct net_device *netdev = dev_get_drvdata(dev);
        struct owl_emac_priv *priv = netdev_priv(netdev);
        int ret;

        ret = clk_bulk_prepare_enable(OWL_EMAC_NCLKS, priv->clks);
        if (ret)
                return ret;

        if (netif_running(netdev)) {
                owl_emac_core_hw_reset(priv);
                owl_emac_core_sw_reset(priv);

                ret = owl_emac_enable(netdev, true);
                if (ret) {
                        clk_bulk_disable_unprepare(OWL_EMAC_NCLKS, priv->clks);
                        return ret;
                }

                netif_device_attach(netdev);
        }

        enable_irq(netdev->irq);

        return 0;
}

static void owl_emac_clk_disable_unprepare(void *data)
{
        struct owl_emac_priv *priv = data;

        clk_bulk_disable_unprepare(OWL_EMAC_NCLKS, priv->clks);
}

static int owl_emac_clk_set_rate(struct owl_emac_priv *priv)
{
        struct device *dev = owl_emac_get_dev(priv);
        unsigned long rate;
        int ret;

        switch (priv->phy_mode) {
        case PHY_INTERFACE_MODE_RMII:
                rate = 50000000;
                break;

        case PHY_INTERFACE_MODE_SMII:
                rate = 125000000;
                break;

        default:
                dev_err(dev, "unsupported phy interface mode %d\n",
                        priv->phy_mode);
                return -EOPNOTSUPP;
        }

        ret = clk_set_rate(priv->clks[OWL_EMAC_CLK_RMII].clk, rate);
        if (ret)
                dev_err(dev, "failed to set RMII clock rate: %d\n", ret);

        return ret;
}

static int owl_emac_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct net_device *netdev;
        struct owl_emac_priv *priv;
        int ret, i;

        netdev = devm_alloc_etherdev(dev, sizeof(*priv));
        if (!netdev)
                return -ENOMEM;

        platform_set_drvdata(pdev, netdev);
        SET_NETDEV_DEV(netdev, dev);

        priv = netdev_priv(netdev);
        priv->netdev = netdev;
        priv->msg_enable = netif_msg_init(-1, OWL_EMAC_DEFAULT_MSG_ENABLE);

        ret = of_get_phy_mode(dev->of_node, &priv->phy_mode);
        if (ret) {
                dev_err(dev, "failed to get phy mode: %d\n", ret);
                return ret;
        }

        spin_lock_init(&priv->lock);

        ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
        if (ret) {
                dev_err(dev, "unsupported DMA mask\n");
                return ret;
        }

        ret = owl_emac_ring_alloc(dev, &priv->rx_ring, OWL_EMAC_RX_RING_SIZE);
        if (ret)
                return ret;

        ret = owl_emac_ring_alloc(dev, &priv->tx_ring, OWL_EMAC_TX_RING_SIZE);
        if (ret)
                return ret;

        priv->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(priv->base))
                return PTR_ERR(priv->base);

        netdev->irq = platform_get_irq(pdev, 0);
        if (netdev->irq < 0)
                return netdev->irq;

        ret = devm_request_irq(dev, netdev->irq, owl_emac_handle_irq,
                               IRQF_SHARED, netdev->name, netdev);
        if (ret) {
                dev_err(dev, "failed to request irq: %d\n", netdev->irq);
                return ret;
        }

        for (i = 0; i < OWL_EMAC_NCLKS; i++)
                priv->clks[i].id = owl_emac_clk_names[i];

        ret = devm_clk_bulk_get(dev, OWL_EMAC_NCLKS, priv->clks);
        if (ret)
                return ret;

        ret = clk_bulk_prepare_enable(OWL_EMAC_NCLKS, priv->clks);
        if (ret)
                return ret;

        ret = devm_add_action_or_reset(dev, owl_emac_clk_disable_unprepare, priv);
        if (ret)
                return ret;

        ret = owl_emac_clk_set_rate(priv);
        if (ret)
                return ret;

        priv->reset = devm_reset_control_get_exclusive(dev, NULL);
        if (IS_ERR(priv->reset))
                return dev_err_probe(dev, PTR_ERR(priv->reset),
                                     "failed to get reset control");

        owl_emac_get_mac_addr(netdev);

        owl_emac_core_hw_reset(priv);
        owl_emac_mdio_clock_enable(priv);

        ret = owl_emac_mdio_init(netdev);
        if (ret) {
                dev_err(dev, "failed to initialize MDIO bus\n");
                return ret;
        }

        ret = owl_emac_phy_init(netdev);
        if (ret) {
                dev_err(dev, "failed to initialize PHY\n");
                return ret;
        }

        INIT_WORK(&priv->mac_reset_task, owl_emac_reset_task);

        netdev->min_mtu = OWL_EMAC_MTU_MIN;
        netdev->max_mtu = OWL_EMAC_MTU_MAX;
        netdev->watchdog_timeo = OWL_EMAC_TX_TIMEOUT;
        netdev->netdev_ops = &owl_emac_netdev_ops;
        netdev->ethtool_ops = &owl_emac_ethtool_ops;
        netif_napi_add(netdev, &priv->napi, owl_emac_poll);

        ret = devm_register_netdev(dev, netdev);
        if (ret) {
                netif_napi_del(&priv->napi);
                phy_disconnect(netdev->phydev);
                return ret;
        }

        return 0;
}

static void owl_emac_remove(struct platform_device *pdev)
{
        struct owl_emac_priv *priv = platform_get_drvdata(pdev);

        netif_napi_del(&priv->napi);
        phy_disconnect(priv->netdev->phydev);
        cancel_work_sync(&priv->mac_reset_task);
}

static const struct of_device_id owl_emac_of_match[] = {
        { .compatible = "actions,owl-emac", },
        { }
};
MODULE_DEVICE_TABLE(of, owl_emac_of_match);

static SIMPLE_DEV_PM_OPS(owl_emac_pm_ops,
                         owl_emac_suspend, owl_emac_resume);

static struct platform_driver owl_emac_driver = {
        .driver = {
                .name = OWL_EMAC_DRVNAME,
                .of_match_table = owl_emac_of_match,
                .pm = &owl_emac_pm_ops,
        },
        .probe = owl_emac_probe,
        .remove = owl_emac_remove,
};
module_platform_driver(owl_emac_driver);

MODULE_DESCRIPTION("Actions Semi Owl SoCs Ethernet MAC Driver");
MODULE_AUTHOR("Actions Semi Inc.");
MODULE_AUTHOR("Cristian Ciocaltea <cristian.ciocaltea@gmail.com>");
MODULE_LICENSE("GPL");