/*
 * Copyright (C) 2015 Mans Rullgard <mans@mansr.com>
 *
 * Mostly rewritten, based on driver from Sigma Designs.  Original
 * copyright notice below.
 *
 *
 * Driver for tangox SMP864x/SMP865x/SMP867x/SMP868x builtin Ethernet Mac.
 *
 * Copyright (C) 2005 Maxime Bizon <mbizon@freebox.fr>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/module.h>
#include <linux/etherdevice.h>
#include <linux/delay.h>
#include <linux/ethtool.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/of_device.h>
#include <linux/of_mdio.h>
#include <linux/of_net.h>
#include <linux/dma-mapping.h>
#include <linux/phy.h>
#include <linux/cache.h>
#include <linux/jiffies.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <asm/barrier.h>

#include "nb8800.h"

static void nb8800_tx_done(struct net_device *dev);
static int nb8800_dma_stop(struct net_device *dev);

static inline u8 nb8800_readb(struct nb8800_priv *priv, int reg)
{
        return readb_relaxed(priv->base + reg);
}

static inline u32 nb8800_readl(struct nb8800_priv *priv, int reg)
{
        return readl_relaxed(priv->base + reg);
}

static inline void nb8800_writeb(struct nb8800_priv *priv, int reg, u8 val)
{
        writeb_relaxed(val, priv->base + reg);
}

static inline void nb8800_writew(struct nb8800_priv *priv, int reg, u16 val)
{
        writew_relaxed(val, priv->base + reg);
}

static inline void nb8800_writel(struct nb8800_priv *priv, int reg, u32 val)
{
        writel_relaxed(val, priv->base + reg);
}

static inline void nb8800_maskb(struct nb8800_priv *priv, int reg,
                                u32 mask, u32 val)
{
        u32 old = nb8800_readb(priv, reg);
        u32 new = (old & ~mask) | (val & mask);

        if (new != old)
                nb8800_writeb(priv, reg, new);
}

static inline void nb8800_maskl(struct nb8800_priv *priv, int reg,
                                u32 mask, u32 val)
{
        u32 old = nb8800_readl(priv, reg);
        u32 new = (old & ~mask) | (val & mask);

        if (new != old)
                nb8800_writel(priv, reg, new);
}

static inline void nb8800_modb(struct nb8800_priv *priv, int reg, u8 bits,
                               bool set)
{
        nb8800_maskb(priv, reg, bits, set ? bits : 0);
}

static inline void nb8800_setb(struct nb8800_priv *priv, int reg, u8 bits)
{
        nb8800_maskb(priv, reg, bits, bits);
}

static inline void nb8800_clearb(struct nb8800_priv *priv, int reg, u8 bits)
{
        nb8800_maskb(priv, reg, bits, 0);
}

static inline void nb8800_modl(struct nb8800_priv *priv, int reg, u32 bits,
                               bool set)
{
        nb8800_maskl(priv, reg, bits, set ? bits : 0);
}

static inline void nb8800_setl(struct nb8800_priv *priv, int reg, u32 bits)
{
        nb8800_maskl(priv, reg, bits, bits);
}

static inline void nb8800_clearl(struct nb8800_priv *priv, int reg, u32 bits)
{
        nb8800_maskl(priv, reg, bits, 0);
}

static int nb8800_mdio_wait(struct mii_bus *bus)
{
        struct nb8800_priv *priv = bus->priv;
        u32 val;

        return readl_poll_timeout_atomic(priv->base + NB8800_MDIO_CMD,
                                         val, !(val & MDIO_CMD_GO), 1, 1000);
}

static int nb8800_mdio_cmd(struct mii_bus *bus, u32 cmd)
{
        struct nb8800_priv *priv = bus->priv;
        int err;

        err = nb8800_mdio_wait(bus);
        if (err)
                return err;

        nb8800_writel(priv, NB8800_MDIO_CMD, cmd);
        udelay(10);
        nb8800_writel(priv, NB8800_MDIO_CMD, cmd | MDIO_CMD_GO);

        return nb8800_mdio_wait(bus);
}

static int nb8800_mdio_read(struct mii_bus *bus, int phy_id, int reg)
{
        struct nb8800_priv *priv = bus->priv;
        u32 val;
        int err;

        err = nb8800_mdio_cmd(bus, MDIO_CMD_ADDR(phy_id) | MDIO_CMD_REG(reg));
        if (err)
                return err;

        val = nb8800_readl(priv, NB8800_MDIO_STS);
        if (val & MDIO_STS_ERR)
                return 0xffff;

        return val & 0xffff;
}

static int nb8800_mdio_write(struct mii_bus *bus, int phy_id, int reg, u16 val)
{
        u32 cmd = MDIO_CMD_ADDR(phy_id) | MDIO_CMD_REG(reg) |
                MDIO_CMD_DATA(val) | MDIO_CMD_WR;

        return nb8800_mdio_cmd(bus, cmd);
}

static void nb8800_mac_tx(struct net_device *dev, bool enable)
{
        struct nb8800_priv *priv = netdev_priv(dev);

        while (nb8800_readl(priv, NB8800_TXC_CR) & TCR_EN)
                cpu_relax();

        nb8800_modb(priv, NB8800_TX_CTL1, TX_EN, enable);
}

static void nb8800_mac_rx(struct net_device *dev, bool enable)
{
        nb8800_modb(netdev_priv(dev), NB8800_RX_CTL, RX_EN, enable);
}

static void nb8800_mac_af(struct net_device *dev, bool enable)
{
        nb8800_modb(netdev_priv(dev), NB8800_RX_CTL, RX_AF_EN, enable);
}

static void nb8800_start_rx(struct net_device *dev)
{
        nb8800_setl(netdev_priv(dev), NB8800_RXC_CR, RCR_EN);
}

static int nb8800_alloc_rx(struct net_device *dev, unsigned int i, bool napi)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        struct nb8800_rx_desc *rxd = &priv->rx_descs[i];
        struct nb8800_rx_buf *rxb = &priv->rx_bufs[i];
        int size = L1_CACHE_ALIGN(RX_BUF_SIZE);
        dma_addr_t dma_addr;
        struct page *page;
        unsigned long offset;
        void *data;

        data = napi ? napi_alloc_frag(size) : netdev_alloc_frag(size);
        if (!data)
                return -ENOMEM;

        page = virt_to_head_page(data);
        offset = data - page_address(page);

        dma_addr = dma_map_page(&dev->dev, page, offset, RX_BUF_SIZE,
                                DMA_FROM_DEVICE);

        if (dma_mapping_error(&dev->dev, dma_addr)) {
                skb_free_frag(data);
                return -ENOMEM;
        }

        rxb->page = page;
        rxb->offset = offset;
        rxd->desc.s_addr = dma_addr;

        return 0;
}

static void nb8800_receive(struct net_device *dev, unsigned int i,
                           unsigned int len)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        struct nb8800_rx_desc *rxd = &priv->rx_descs[i];
        struct page *page = priv->rx_bufs[i].page;
        int offset = priv->rx_bufs[i].offset;
        void *data = page_address(page) + offset;
        dma_addr_t dma = rxd->desc.s_addr;
        struct sk_buff *skb;
        unsigned int size;
        int err;

        size = len <= RX_COPYBREAK ? len : RX_COPYHDR;

        skb = napi_alloc_skb(&priv->napi, size);
        if (!skb) {
                netdev_err(dev, "rx skb allocation failed\n");
                dev->stats.rx_dropped++;
                return;
        }

        if (len <= RX_COPYBREAK) {
                dma_sync_single_for_cpu(&dev->dev, dma, len, DMA_FROM_DEVICE);
                skb_put_data(skb, data, len);
                dma_sync_single_for_device(&dev->dev, dma, len,
                                           DMA_FROM_DEVICE);
        } else {
                err = nb8800_alloc_rx(dev, i, true);
                if (err) {
                        netdev_err(dev, "rx buffer allocation failed\n");
                        dev->stats.rx_dropped++;
                        dev_kfree_skb(skb);
                        return;
                }

                dma_unmap_page(&dev->dev, dma, RX_BUF_SIZE, DMA_FROM_DEVICE);
                skb_put_data(skb, data, RX_COPYHDR);
                skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page,
                                offset + RX_COPYHDR, len - RX_COPYHDR,
                                RX_BUF_SIZE);
        }

        skb->protocol = eth_type_trans(skb, dev);
        napi_gro_receive(&priv->napi, skb);
}

static void nb8800_rx_error(struct net_device *dev, u32 report)
{
        if (report & RX_LENGTH_ERR)
                dev->stats.rx_length_errors++;

        if (report & RX_FCS_ERR)
                dev->stats.rx_crc_errors++;

        if (report & RX_FIFO_OVERRUN)
                dev->stats.rx_fifo_errors++;

        if (report & RX_ALIGNMENT_ERROR)
                dev->stats.rx_frame_errors++;

        dev->stats.rx_errors++;
}

static int nb8800_poll(struct napi_struct *napi, int budget)
{
        struct net_device *dev = napi->dev;
        struct nb8800_priv *priv = netdev_priv(dev);
        struct nb8800_rx_desc *rxd;
        unsigned int last = priv->rx_eoc;
        unsigned int next;
        int work = 0;

        nb8800_tx_done(dev);

again:
        do {
                struct nb8800_rx_buf *rxb;
                unsigned int len;

                next = (last + 1) % RX_DESC_COUNT;

                rxb = &priv->rx_bufs[next];
                rxd = &priv->rx_descs[next];

                if (!rxd->report)
                        break;

                len = RX_BYTES_TRANSFERRED(rxd->report);

                if (IS_RX_ERROR(rxd->report))
                        nb8800_rx_error(dev, rxd->report);
                else
                        nb8800_receive(dev, next, len);

                dev->stats.rx_packets++;
                dev->stats.rx_bytes += len;

                if (rxd->report & RX_MULTICAST_PKT)
                        dev->stats.multicast++;

                rxd->report = 0;
                last = next;
                work++;
        } while (work < budget);

        if (work) {
                priv->rx_descs[last].desc.config |= DESC_EOC;
                wmb();  /* ensure new EOC is written before clearing old */
                priv->rx_descs[priv->rx_eoc].desc.config &= ~DESC_EOC;
                priv->rx_eoc = last;
                nb8800_start_rx(dev);
        }

        if (work < budget) {
                nb8800_writel(priv, NB8800_RX_ITR, priv->rx_itr_irq);

                /* If a packet arrived after we last checked but
                 * before writing RX_ITR, the interrupt will be
                 * delayed, so we retrieve it now.
                 */
                if (priv->rx_descs[next].report)
                        goto again;

                napi_complete_done(napi, work);
        }

        return work;
}

static void __nb8800_tx_dma_start(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        struct nb8800_tx_buf *txb;
        u32 txc_cr;

        txb = &priv->tx_bufs[priv->tx_queue];
        if (!txb->ready)
                return;

        txc_cr = nb8800_readl(priv, NB8800_TXC_CR);
        if (txc_cr & TCR_EN)
                return;

        nb8800_writel(priv, NB8800_TX_DESC_ADDR, txb->dma_desc);
        wmb();          /* ensure desc addr is written before starting DMA */
        nb8800_writel(priv, NB8800_TXC_CR, txc_cr | TCR_EN);

        priv->tx_queue = (priv->tx_queue + txb->chain_len) % TX_DESC_COUNT;
}

static void nb8800_tx_dma_start(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);

        spin_lock_irq(&priv->tx_lock);
        __nb8800_tx_dma_start(dev);
        spin_unlock_irq(&priv->tx_lock);
}

static void nb8800_tx_dma_start_irq(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);

        spin_lock(&priv->tx_lock);
        __nb8800_tx_dma_start(dev);
        spin_unlock(&priv->tx_lock);
}

static int nb8800_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        struct nb8800_tx_desc *txd;
        struct nb8800_tx_buf *txb;
        struct nb8800_dma_desc *desc;
        dma_addr_t dma_addr;
        unsigned int dma_len;
        unsigned int align;
        unsigned int next;

        if (atomic_read(&priv->tx_free) <= NB8800_DESC_LOW) {
                netif_stop_queue(dev);
                return NETDEV_TX_BUSY;
        }

        align = (8 - (uintptr_t)skb->data) & 7;

        dma_len = skb->len - align;
        dma_addr = dma_map_single(&dev->dev, skb->data + align,
                                  dma_len, DMA_TO_DEVICE);

        if (dma_mapping_error(&dev->dev, dma_addr)) {
                netdev_err(dev, "tx dma mapping error\n");
                kfree_skb(skb);
                dev->stats.tx_dropped++;
                return NETDEV_TX_OK;
        }

        if (atomic_dec_return(&priv->tx_free) <= NB8800_DESC_LOW) {
                netif_stop_queue(dev);
                skb->xmit_more = 0;
        }

        next = priv->tx_next;
        txb = &priv->tx_bufs[next];
        txd = &priv->tx_descs[next];
        desc = &txd->desc[0];

        next = (next + 1) % TX_DESC_COUNT;

        if (align) {
                memcpy(txd->buf, skb->data, align);

                desc->s_addr =
                        txb->dma_desc + offsetof(struct nb8800_tx_desc, buf);
                desc->n_addr = txb->dma_desc + sizeof(txd->desc[0]);
                desc->config = DESC_BTS(2) | DESC_DS | align;

                desc++;
        }

        desc->s_addr = dma_addr;
        desc->n_addr = priv->tx_bufs[next].dma_desc;
        desc->config = DESC_BTS(2) | DESC_DS | DESC_EOF | dma_len;

        if (!skb->xmit_more)
                desc->config |= DESC_EOC;

        txb->skb = skb;
        txb->dma_addr = dma_addr;
        txb->dma_len = dma_len;

        if (!priv->tx_chain) {
                txb->chain_len = 1;
                priv->tx_chain = txb;
        } else {
                priv->tx_chain->chain_len++;
        }

        netdev_sent_queue(dev, skb->len);

        priv->tx_next = next;

        if (!skb->xmit_more) {
                smp_wmb();
                priv->tx_chain->ready = true;
                priv->tx_chain = NULL;
                nb8800_tx_dma_start(dev);
        }

        return NETDEV_TX_OK;
}

static void nb8800_tx_error(struct net_device *dev, u32 report)
{
        if (report & TX_LATE_COLLISION)
                dev->stats.collisions++;

        if (report & TX_PACKET_DROPPED)
                dev->stats.tx_dropped++;

        if (report & TX_FIFO_UNDERRUN)
                dev->stats.tx_fifo_errors++;

        dev->stats.tx_errors++;
}

static void nb8800_tx_done(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        unsigned int limit = priv->tx_next;
        unsigned int done = priv->tx_done;
        unsigned int packets = 0;
        unsigned int len = 0;

        while (done != limit) {
                struct nb8800_tx_desc *txd = &priv->tx_descs[done];
                struct nb8800_tx_buf *txb = &priv->tx_bufs[done];
                struct sk_buff *skb;

                if (!txd->report)
                        break;

                skb = txb->skb;
                len += skb->len;

                dma_unmap_single(&dev->dev, txb->dma_addr, txb->dma_len,
                                 DMA_TO_DEVICE);

                if (IS_TX_ERROR(txd->report)) {
                        nb8800_tx_error(dev, txd->report);
                        kfree_skb(skb);
                } else {
                        consume_skb(skb);
                }

                dev->stats.tx_packets++;
                dev->stats.tx_bytes += TX_BYTES_TRANSFERRED(txd->report);
                dev->stats.collisions += TX_EARLY_COLLISIONS(txd->report);

                txb->skb = NULL;
                txb->ready = false;
                txd->report = 0;

                done = (done + 1) % TX_DESC_COUNT;
                packets++;
        }

        if (packets) {
                smp_mb__before_atomic();
                atomic_add(packets, &priv->tx_free);
                netdev_completed_queue(dev, packets, len);
                netif_wake_queue(dev);
                priv->tx_done = done;
        }
}

static irqreturn_t nb8800_irq(int irq, void *dev_id)
{
        struct net_device *dev = dev_id;
        struct nb8800_priv *priv = netdev_priv(dev);
        irqreturn_t ret = IRQ_NONE;
        u32 val;

        /* tx interrupt */
        val = nb8800_readl(priv, NB8800_TXC_SR);
        if (val) {
                nb8800_writel(priv, NB8800_TXC_SR, val);

                if (val & TSR_DI)
                        nb8800_tx_dma_start_irq(dev);

                if (val & TSR_TI)
                        napi_schedule_irqoff(&priv->napi);

                if (unlikely(val & TSR_DE))
                        netdev_err(dev, "TX DMA error\n");

                /* should never happen with automatic status retrieval */
                if (unlikely(val & TSR_TO))
                        netdev_err(dev, "TX Status FIFO overflow\n");

                ret = IRQ_HANDLED;
        }

        /* rx interrupt */
        val = nb8800_readl(priv, NB8800_RXC_SR);
        if (val) {
                nb8800_writel(priv, NB8800_RXC_SR, val);

                if (likely(val & (RSR_RI | RSR_DI))) {
                        nb8800_writel(priv, NB8800_RX_ITR, priv->rx_itr_poll);
                        napi_schedule_irqoff(&priv->napi);
                }

                if (unlikely(val & RSR_DE))
                        netdev_err(dev, "RX DMA error\n");

                /* should never happen with automatic status retrieval */
                if (unlikely(val & RSR_RO))
                        netdev_err(dev, "RX Status FIFO overflow\n");

                ret = IRQ_HANDLED;
        }

        return ret;
}

static void nb8800_mac_config(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        bool gigabit = priv->speed == SPEED_1000;
        u32 mac_mode_mask = RGMII_MODE | HALF_DUPLEX | GMAC_MODE;
        u32 mac_mode = 0;
        u32 slot_time;
        u32 phy_clk;
        u32 ict;

        if (!priv->duplex)
                mac_mode |= HALF_DUPLEX;

        if (gigabit) {
                if (phy_interface_is_rgmii(dev->phydev))
                        mac_mode |= RGMII_MODE;

                mac_mode |= GMAC_MODE;
                phy_clk = 125000000;

                /* Should be 512 but register is only 8 bits */
                slot_time = 255;
        } else {
                phy_clk = 25000000;
                slot_time = 128;
        }

        ict = DIV_ROUND_UP(phy_clk, clk_get_rate(priv->clk));

        nb8800_writeb(priv, NB8800_IC_THRESHOLD, ict);
        nb8800_writeb(priv, NB8800_SLOT_TIME, slot_time);
        nb8800_maskb(priv, NB8800_MAC_MODE, mac_mode_mask, mac_mode);
}

static void nb8800_pause_config(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        struct phy_device *phydev = dev->phydev;
        u32 rxcr;

        if (priv->pause_aneg) {
                if (!phydev || !phydev->link)
                        return;

                priv->pause_rx = phydev->pause;
                priv->pause_tx = phydev->pause ^ phydev->asym_pause;
        }

        nb8800_modb(priv, NB8800_RX_CTL, RX_PAUSE_EN, priv->pause_rx);

        rxcr = nb8800_readl(priv, NB8800_RXC_CR);
        if (!!(rxcr & RCR_FL) == priv->pause_tx)
                return;

        if (netif_running(dev)) {
                napi_disable(&priv->napi);
                netif_tx_lock_bh(dev);
                nb8800_dma_stop(dev);
                nb8800_modl(priv, NB8800_RXC_CR, RCR_FL, priv->pause_tx);
                nb8800_start_rx(dev);
                netif_tx_unlock_bh(dev);
                napi_enable(&priv->napi);
        } else {
                nb8800_modl(priv, NB8800_RXC_CR, RCR_FL, priv->pause_tx);
        }
}

static void nb8800_link_reconfigure(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        struct phy_device *phydev = dev->phydev;
        int change = 0;

        if (phydev->link) {
                if (phydev->speed != priv->speed) {
                        priv->speed = phydev->speed;
                        change = 1;
                }

                if (phydev->duplex != priv->duplex) {
                        priv->duplex = phydev->duplex;
                        change = 1;
                }

                if (change)
                        nb8800_mac_config(dev);

                nb8800_pause_config(dev);
        }

        if (phydev->link != priv->link) {
                priv->link = phydev->link;
                change = 1;
        }

        if (change)
                phy_print_status(phydev);
}

static void nb8800_update_mac_addr(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        int i;

        for (i = 0; i < ETH_ALEN; i++)
                nb8800_writeb(priv, NB8800_SRC_ADDR(i), dev->dev_addr[i]);

        for (i = 0; i < ETH_ALEN; i++)
                nb8800_writeb(priv, NB8800_UC_ADDR(i), dev->dev_addr[i]);
}

static int nb8800_set_mac_address(struct net_device *dev, void *addr)
{
        struct sockaddr *sock = addr;

        if (netif_running(dev))
                return -EBUSY;

        ether_addr_copy(dev->dev_addr, sock->sa_data);
        nb8800_update_mac_addr(dev);

        return 0;
}

static void nb8800_mc_init(struct net_device *dev, int val)
{
        struct nb8800_priv *priv = netdev_priv(dev);

        nb8800_writeb(priv, NB8800_MC_INIT, val);
        readb_poll_timeout_atomic(priv->base + NB8800_MC_INIT, val, !val,
                                  1, 1000);
}

static void nb8800_set_rx_mode(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        struct netdev_hw_addr *ha;
        int i;

        if (dev->flags & (IFF_PROMISC | IFF_ALLMULTI)) {
                nb8800_mac_af(dev, false);
                return;
        }

        nb8800_mac_af(dev, true);
        nb8800_mc_init(dev, 0);

        netdev_for_each_mc_addr(ha, dev) {
                for (i = 0; i < ETH_ALEN; i++)
                        nb8800_writeb(priv, NB8800_MC_ADDR(i), ha->addr[i]);

                nb8800_mc_init(dev, 0xff);
        }
}

#define RX_DESC_SIZE (RX_DESC_COUNT * sizeof(struct nb8800_rx_desc))
#define TX_DESC_SIZE (TX_DESC_COUNT * sizeof(struct nb8800_tx_desc))

static void nb8800_dma_free(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        unsigned int i;

        if (priv->rx_bufs) {
                for (i = 0; i < RX_DESC_COUNT; i++)
                        if (priv->rx_bufs[i].page)
                                put_page(priv->rx_bufs[i].page);

                kfree(priv->rx_bufs);
                priv->rx_bufs = NULL;
        }

        if (priv->tx_bufs) {
                for (i = 0; i < TX_DESC_COUNT; i++)
                        kfree_skb(priv->tx_bufs[i].skb);

                kfree(priv->tx_bufs);
                priv->tx_bufs = NULL;
        }

        if (priv->rx_descs) {
                dma_free_coherent(dev->dev.parent, RX_DESC_SIZE, priv->rx_descs,
                                  priv->rx_desc_dma);
                priv->rx_descs = NULL;
        }

        if (priv->tx_descs) {
                dma_free_coherent(dev->dev.parent, TX_DESC_SIZE, priv->tx_descs,
                                  priv->tx_desc_dma);
                priv->tx_descs = NULL;
        }
}

static void nb8800_dma_reset(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        struct nb8800_rx_desc *rxd;
        struct nb8800_tx_desc *txd;
        unsigned int i;

        for (i = 0; i < RX_DESC_COUNT; i++) {
                dma_addr_t rx_dma = priv->rx_desc_dma + i * sizeof(*rxd);

                rxd = &priv->rx_descs[i];
                rxd->desc.n_addr = rx_dma + sizeof(*rxd);
                rxd->desc.r_addr =
                        rx_dma + offsetof(struct nb8800_rx_desc, report);
                rxd->desc.config = priv->rx_dma_config;
                rxd->report = 0;
        }

        rxd->desc.n_addr = priv->rx_desc_dma;
        rxd->desc.config |= DESC_EOC;

        priv->rx_eoc = RX_DESC_COUNT - 1;

        for (i = 0; i < TX_DESC_COUNT; i++) {
                struct nb8800_tx_buf *txb = &priv->tx_bufs[i];
                dma_addr_t r_dma = txb->dma_desc +
                        offsetof(struct nb8800_tx_desc, report);

                txd = &priv->tx_descs[i];
                txd->desc[0].r_addr = r_dma;
                txd->desc[1].r_addr = r_dma;
                txd->report = 0;
        }

        priv->tx_next = 0;
        priv->tx_queue = 0;
        priv->tx_done = 0;
        atomic_set(&priv->tx_free, TX_DESC_COUNT);

        nb8800_writel(priv, NB8800_RX_DESC_ADDR, priv->rx_desc_dma);

        wmb();          /* ensure all setup is written before starting */
}

static int nb8800_dma_init(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        unsigned int n_rx = RX_DESC_COUNT;
        unsigned int n_tx = TX_DESC_COUNT;
        unsigned int i;
        int err;

        priv->rx_descs = dma_alloc_coherent(dev->dev.parent, RX_DESC_SIZE,
                                            &priv->rx_desc_dma, GFP_KERNEL);
        if (!priv->rx_descs)
                goto err_out;

        priv->rx_bufs = kcalloc(n_rx, sizeof(*priv->rx_bufs), GFP_KERNEL);
        if (!priv->rx_bufs)
                goto err_out;

        for (i = 0; i < n_rx; i++) {
                err = nb8800_alloc_rx(dev, i, false);
                if (err)
                        goto err_out;
        }

        priv->tx_descs = dma_alloc_coherent(dev->dev.parent, TX_DESC_SIZE,
                                            &priv->tx_desc_dma, GFP_KERNEL);
        if (!priv->tx_descs)
                goto err_out;

        priv->tx_bufs = kcalloc(n_tx, sizeof(*priv->tx_bufs), GFP_KERNEL);
        if (!priv->tx_bufs)
                goto err_out;

        for (i = 0; i < n_tx; i++)
                priv->tx_bufs[i].dma_desc =
                        priv->tx_desc_dma + i * sizeof(struct nb8800_tx_desc);

        nb8800_dma_reset(dev);

        return 0;

err_out:
        nb8800_dma_free(dev);

        return -ENOMEM;
}

static int nb8800_dma_stop(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        struct nb8800_tx_buf *txb = &priv->tx_bufs[0];
        struct nb8800_tx_desc *txd = &priv->tx_descs[0];
        int retry = 5;
        u32 txcr;
        u32 rxcr;
        int err;
        unsigned int i;

        /* wait for tx to finish */
        err = readl_poll_timeout_atomic(priv->base + NB8800_TXC_CR, txcr,
                                        !(txcr & TCR_EN) &&
                                        priv->tx_done == priv->tx_next,
                                        1000, 1000000);
        if (err)
                return err;

        /* The rx DMA only stops if it reaches the end of chain.
         * To make this happen, we set the EOC flag on all rx
         * descriptors, put the device in loopback mode, and send
         * a few dummy frames.  The interrupt handler will ignore
         * these since NAPI is disabled and no real frames are in
         * the tx queue.
         */

        for (i = 0; i < RX_DESC_COUNT; i++)
                priv->rx_descs[i].desc.config |= DESC_EOC;

        txd->desc[0].s_addr =
                txb->dma_desc + offsetof(struct nb8800_tx_desc, buf);
        txd->desc[0].config = DESC_BTS(2) | DESC_DS | DESC_EOF | DESC_EOC | 8;
        memset(txd->buf, 0, sizeof(txd->buf));

        nb8800_mac_af(dev, false);
        nb8800_setb(priv, NB8800_MAC_MODE, LOOPBACK_EN);

        do {
                nb8800_writel(priv, NB8800_TX_DESC_ADDR, txb->dma_desc);
                wmb();
                nb8800_writel(priv, NB8800_TXC_CR, txcr | TCR_EN);

                err = readl_poll_timeout_atomic(priv->base + NB8800_RXC_CR,
                                                rxcr, !(rxcr & RCR_EN),
                                                1000, 100000);
        } while (err && --retry);

        nb8800_mac_af(dev, true);
        nb8800_clearb(priv, NB8800_MAC_MODE, LOOPBACK_EN);
        nb8800_dma_reset(dev);

        return retry ? 0 : -ETIMEDOUT;
}

static void nb8800_pause_adv(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        struct phy_device *phydev = dev->phydev;
        u32 adv = 0;

        if (!phydev)
                return;

        if (priv->pause_rx)
                adv |= ADVERTISED_Pause | ADVERTISED_Asym_Pause;
        if (priv->pause_tx)
                adv ^= ADVERTISED_Asym_Pause;

        phydev->supported |= adv;
        phydev->advertising |= adv;
}

static int nb8800_open(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        struct phy_device *phydev;
        int err;

        /* clear any pending interrupts */
        nb8800_writel(priv, NB8800_RXC_SR, 0xf);
        nb8800_writel(priv, NB8800_TXC_SR, 0xf);

        err = nb8800_dma_init(dev);
        if (err)
                return err;

        err = request_irq(dev->irq, nb8800_irq, 0, dev_name(&dev->dev), dev);
        if (err)
                goto err_free_dma;

        nb8800_mac_rx(dev, true);
        nb8800_mac_tx(dev, true);

        phydev = of_phy_connect(dev, priv->phy_node,
                                nb8800_link_reconfigure, 0,
                                priv->phy_mode);
        if (!phydev) {
                err = -ENODEV;
                goto err_free_irq;
        }

        nb8800_pause_adv(dev);

        netdev_reset_queue(dev);
        napi_enable(&priv->napi);
        netif_start_queue(dev);

        nb8800_start_rx(dev);
        phy_start(phydev);

        return 0;

err_free_irq:
        free_irq(dev->irq, dev);
err_free_dma:
        nb8800_dma_free(dev);

        return err;
}

static int nb8800_stop(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        struct phy_device *phydev = dev->phydev;

        phy_stop(phydev);

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

        nb8800_dma_stop(dev);
        nb8800_mac_rx(dev, false);
        nb8800_mac_tx(dev, false);

        phy_disconnect(phydev);

        free_irq(dev->irq, dev);

        nb8800_dma_free(dev);

        return 0;
}

static int nb8800_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
{
        return phy_mii_ioctl(dev->phydev, rq, cmd);
}

static const struct net_device_ops nb8800_netdev_ops = {
        .ndo_open               = nb8800_open,
        .ndo_stop               = nb8800_stop,
        .ndo_start_xmit         = nb8800_xmit,
        .ndo_set_mac_address    = nb8800_set_mac_address,
        .ndo_set_rx_mode        = nb8800_set_rx_mode,
        .ndo_do_ioctl           = nb8800_ioctl,
        .ndo_validate_addr      = eth_validate_addr,
};

static void nb8800_get_pauseparam(struct net_device *dev,
                                  struct ethtool_pauseparam *pp)
{
        struct nb8800_priv *priv = netdev_priv(dev);

        pp->autoneg = priv->pause_aneg;
        pp->rx_pause = priv->pause_rx;
        pp->tx_pause = priv->pause_tx;
}

static int nb8800_set_pauseparam(struct net_device *dev,
                                 struct ethtool_pauseparam *pp)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        struct phy_device *phydev = dev->phydev;

        priv->pause_aneg = pp->autoneg;
        priv->pause_rx = pp->rx_pause;
        priv->pause_tx = pp->tx_pause;

        nb8800_pause_adv(dev);

        if (!priv->pause_aneg)
                nb8800_pause_config(dev);
        else if (phydev)
                phy_start_aneg(phydev);

        return 0;
}

static const char nb8800_stats_names[][ETH_GSTRING_LEN] = {
        "rx_bytes_ok",
        "rx_frames_ok",
        "rx_undersize_frames",
        "rx_fragment_frames",
        "rx_64_byte_frames",
        "rx_127_byte_frames",
        "rx_255_byte_frames",
        "rx_511_byte_frames",
        "rx_1023_byte_frames",
        "rx_max_size_frames",
        "rx_oversize_frames",
        "rx_bad_fcs_frames",
        "rx_broadcast_frames",
        "rx_multicast_frames",
        "rx_control_frames",
        "rx_pause_frames",
        "rx_unsup_control_frames",
        "rx_align_error_frames",
        "rx_overrun_frames",
        "rx_jabber_frames",
        "rx_bytes",
        "rx_frames",

        "tx_bytes_ok",
        "tx_frames_ok",
        "tx_64_byte_frames",
        "tx_127_byte_frames",
        "tx_255_byte_frames",
        "tx_511_byte_frames",
        "tx_1023_byte_frames",
        "tx_max_size_frames",
        "tx_oversize_frames",
        "tx_broadcast_frames",
        "tx_multicast_frames",
        "tx_control_frames",
        "tx_pause_frames",
        "tx_underrun_frames",
        "tx_single_collision_frames",
        "tx_multi_collision_frames",
        "tx_deferred_collision_frames",
        "tx_late_collision_frames",
        "tx_excessive_collision_frames",
        "tx_bytes",
        "tx_frames",
        "tx_collisions",
};

#define NB8800_NUM_STATS ARRAY_SIZE(nb8800_stats_names)

static int nb8800_get_sset_count(struct net_device *dev, int sset)
{
        if (sset == ETH_SS_STATS)
                return NB8800_NUM_STATS;

        return -EOPNOTSUPP;
}

static void nb8800_get_strings(struct net_device *dev, u32 sset, u8 *buf)
{
        if (sset == ETH_SS_STATS)
                memcpy(buf, &nb8800_stats_names, sizeof(nb8800_stats_names));
}

static u32 nb8800_read_stat(struct net_device *dev, int index)
{
        struct nb8800_priv *priv = netdev_priv(dev);

        nb8800_writeb(priv, NB8800_STAT_INDEX, index);

        return nb8800_readl(priv, NB8800_STAT_DATA);
}

static void nb8800_get_ethtool_stats(struct net_device *dev,
                                     struct ethtool_stats *estats, u64 *st)
{
        unsigned int i;
        u32 rx, tx;

        for (i = 0; i < NB8800_NUM_STATS / 2; i++) {
                rx = nb8800_read_stat(dev, i);
                tx = nb8800_read_stat(dev, i | 0x80);
                st[i] = rx;
                st[i + NB8800_NUM_STATS / 2] = tx;
        }
}

static const struct ethtool_ops nb8800_ethtool_ops = {
        .nway_reset             = phy_ethtool_nway_reset,
        .get_link               = ethtool_op_get_link,
        .get_pauseparam         = nb8800_get_pauseparam,
        .set_pauseparam         = nb8800_set_pauseparam,
        .get_sset_count         = nb8800_get_sset_count,
        .get_strings            = nb8800_get_strings,
        .get_ethtool_stats      = nb8800_get_ethtool_stats,
        .get_link_ksettings     = phy_ethtool_get_link_ksettings,
        .set_link_ksettings     = phy_ethtool_set_link_ksettings,
};

static int nb8800_hw_init(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        u32 val;

        val = TX_RETRY_EN | TX_PAD_EN | TX_APPEND_FCS;
        nb8800_writeb(priv, NB8800_TX_CTL1, val);

        /* Collision retry count */
        nb8800_writeb(priv, NB8800_TX_CTL2, 5);

        val = RX_PAD_STRIP | RX_AF_EN;
        nb8800_writeb(priv, NB8800_RX_CTL, val);

        /* Chosen by fair dice roll */
        nb8800_writeb(priv, NB8800_RANDOM_SEED, 4);

        /* TX cycles per deferral period */
        nb8800_writeb(priv, NB8800_TX_SDP, 12);

        /* The following three threshold values have been
         * experimentally determined for good results.
         */

        /* RX/TX FIFO threshold for partial empty (64-bit entries) */
        nb8800_writeb(priv, NB8800_PE_THRESHOLD, 0);

        /* RX/TX FIFO threshold for partial full (64-bit entries) */
        nb8800_writeb(priv, NB8800_PF_THRESHOLD, 255);

        /* Buffer size for transmit (64-bit entries) */
        nb8800_writeb(priv, NB8800_TX_BUFSIZE, 64);

        /* Configure tx DMA */

        val = nb8800_readl(priv, NB8800_TXC_CR);
        val &= TCR_LE;          /* keep endian setting */
        val |= TCR_DM;          /* DMA descriptor mode */
        val |= TCR_RS;          /* automatically store tx status  */
        val |= TCR_DIE;         /* interrupt on DMA chain completion */
        val |= TCR_TFI(7);      /* interrupt after 7 frames transmitted */
        val |= TCR_BTS(2);      /* 32-byte bus transaction size */
        nb8800_writel(priv, NB8800_TXC_CR, val);

        /* TX complete interrupt after 10 ms or 7 frames (see above) */
        val = clk_get_rate(priv->clk) / 100;
        nb8800_writel(priv, NB8800_TX_ITR, val);

        /* Configure rx DMA */

        val = nb8800_readl(priv, NB8800_RXC_CR);
        val &= RCR_LE;          /* keep endian setting */
        val |= RCR_DM;          /* DMA descriptor mode */
        val |= RCR_RS;          /* automatically store rx status */
        val |= RCR_DIE;         /* interrupt at end of DMA chain */
        val |= RCR_RFI(7);      /* interrupt after 7 frames received */
        val |= RCR_BTS(2);      /* 32-byte bus transaction size */
        nb8800_writel(priv, NB8800_RXC_CR, val);

        /* The rx interrupt can fire before the DMA has completed
         * unless a small delay is added.  50 us is hopefully enough.
         */
        priv->rx_itr_irq = clk_get_rate(priv->clk) / 20000;

        /* In NAPI poll mode we want to disable interrupts, but the
         * hardware does not permit this.  Delay 10 ms instead.
         */
        priv->rx_itr_poll = clk_get_rate(priv->clk) / 100;

        nb8800_writel(priv, NB8800_RX_ITR, priv->rx_itr_irq);

        priv->rx_dma_config = RX_BUF_SIZE | DESC_BTS(2) | DESC_DS | DESC_EOF;

        /* Flow control settings */

        /* Pause time of 0.1 ms */
        val = 100000 / 512;
        nb8800_writeb(priv, NB8800_PQ1, val >> 8);
        nb8800_writeb(priv, NB8800_PQ2, val & 0xff);

        /* Auto-negotiate by default */
        priv->pause_aneg = true;
        priv->pause_rx = true;
        priv->pause_tx = true;

        nb8800_mc_init(dev, 0);

        return 0;
}

static int nb8800_tangox_init(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        u32 pad_mode = PAD_MODE_MII;

        switch (priv->phy_mode) {
        case PHY_INTERFACE_MODE_MII:
        case PHY_INTERFACE_MODE_GMII:
                pad_mode = PAD_MODE_MII;
                break;

        case PHY_INTERFACE_MODE_RGMII:
        case PHY_INTERFACE_MODE_RGMII_ID:
        case PHY_INTERFACE_MODE_RGMII_RXID:
        case PHY_INTERFACE_MODE_RGMII_TXID:
                pad_mode = PAD_MODE_RGMII;
                break;

        default:
                dev_err(dev->dev.parent, "unsupported phy mode %s\n",
                        phy_modes(priv->phy_mode));
                return -EINVAL;
        }

        nb8800_writeb(priv, NB8800_TANGOX_PAD_MODE, pad_mode);

        return 0;
}

static int nb8800_tangox_reset(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        int clk_div;

        nb8800_writeb(priv, NB8800_TANGOX_RESET, 0);
        usleep_range(1000, 10000);
        nb8800_writeb(priv, NB8800_TANGOX_RESET, 1);

        wmb();          /* ensure reset is cleared before proceeding */

        clk_div = DIV_ROUND_UP(clk_get_rate(priv->clk), 2 * MAX_MDC_CLOCK);
        nb8800_writew(priv, NB8800_TANGOX_MDIO_CLKDIV, clk_div);

        return 0;
}

static const struct nb8800_ops nb8800_tangox_ops = {
        .init   = nb8800_tangox_init,
        .reset  = nb8800_tangox_reset,
};

static int nb8800_tango4_init(struct net_device *dev)
{
        struct nb8800_priv *priv = netdev_priv(dev);
        int err;

        err = nb8800_tangox_init(dev);
        if (err)
                return err;

        /* On tango4 interrupt on DMA completion per frame works and gives
         * better performance despite generating more rx interrupts.
         */

        /* Disable unnecessary interrupt on rx completion */
        nb8800_clearl(priv, NB8800_RXC_CR, RCR_RFI(7));

        /* Request interrupt on descriptor DMA completion */
        priv->rx_dma_config |= DESC_ID;

        return 0;
}

static const struct nb8800_ops nb8800_tango4_ops = {
        .init   = nb8800_tango4_init,
        .reset  = nb8800_tangox_reset,
};

static const struct of_device_id nb8800_dt_ids[] = {
        {
                .compatible = "aurora,nb8800",
        },
        {
                .compatible = "sigma,smp8642-ethernet",
                .data = &nb8800_tangox_ops,
        },
        {
                .compatible = "sigma,smp8734-ethernet",
                .data = &nb8800_tango4_ops,
        },
        { }
};
MODULE_DEVICE_TABLE(of, nb8800_dt_ids);

static int nb8800_probe(struct platform_device *pdev)
{
        const struct of_device_id *match;
        const struct nb8800_ops *ops = NULL;
        struct nb8800_priv *priv;
        struct resource *res;
        struct net_device *dev;
        struct mii_bus *bus;
        const unsigned char *mac;
        void __iomem *base;
        int irq;
        int ret;

        match = of_match_device(nb8800_dt_ids, &pdev->dev);
        if (match)
                ops = match->data;

        irq = platform_get_irq(pdev, 0);
        if (irq <= 0) {
                dev_err(&pdev->dev, "No IRQ\n");
                return -EINVAL;
        }

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        base = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(base))
                return PTR_ERR(base);

        dev_dbg(&pdev->dev, "AU-NB8800 Ethernet at %pa\n", &res->start);

        dev = alloc_etherdev(sizeof(*priv));
        if (!dev)
                return -ENOMEM;

        platform_set_drvdata(pdev, dev);
        SET_NETDEV_DEV(dev, &pdev->dev);

        priv = netdev_priv(dev);
        priv->base = base;

        priv->phy_mode = of_get_phy_mode(pdev->dev.of_node);
        if (priv->phy_mode < 0)
                priv->phy_mode = PHY_INTERFACE_MODE_RGMII;

        priv->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(priv->clk)) {
                dev_err(&pdev->dev, "failed to get clock\n");
                ret = PTR_ERR(priv->clk);
                goto err_free_dev;
        }

        ret = clk_prepare_enable(priv->clk);
        if (ret)
                goto err_free_dev;

        spin_lock_init(&priv->tx_lock);

        if (ops && ops->reset) {
                ret = ops->reset(dev);
                if (ret)
                        goto err_disable_clk;
        }

        bus = devm_mdiobus_alloc(&pdev->dev);
        if (!bus) {
                ret = -ENOMEM;
                goto err_disable_clk;
        }

        bus->name = "nb8800-mii";
        bus->read = nb8800_mdio_read;
        bus->write = nb8800_mdio_write;
        bus->parent = &pdev->dev;
        snprintf(bus->id, MII_BUS_ID_SIZE, "%lx.nb8800-mii",
                 (unsigned long)res->start);
        bus->priv = priv;

        ret = of_mdiobus_register(bus, pdev->dev.of_node);
        if (ret) {
                dev_err(&pdev->dev, "failed to register MII bus\n");
                goto err_disable_clk;
        }

        if (of_phy_is_fixed_link(pdev->dev.of_node)) {
                ret = of_phy_register_fixed_link(pdev->dev.of_node);
                if (ret < 0) {
                        dev_err(&pdev->dev, "bad fixed-link spec\n");
                        goto err_free_bus;
                }
                priv->phy_node = of_node_get(pdev->dev.of_node);
        }

        if (!priv->phy_node)
                priv->phy_node = of_parse_phandle(pdev->dev.of_node,
                                                  "phy-handle", 0);

        if (!priv->phy_node) {
                dev_err(&pdev->dev, "no PHY specified\n");
                ret = -ENODEV;
                goto err_free_bus;
        }

        priv->mii_bus = bus;

        ret = nb8800_hw_init(dev);
        if (ret)
                goto err_deregister_fixed_link;

        if (ops && ops->init) {
                ret = ops->init(dev);
                if (ret)
                        goto err_deregister_fixed_link;
        }

        dev->netdev_ops = &nb8800_netdev_ops;
        dev->ethtool_ops = &nb8800_ethtool_ops;
        dev->flags |= IFF_MULTICAST;
        dev->irq = irq;

        mac = of_get_mac_address(pdev->dev.of_node);
        if (mac)
                ether_addr_copy(dev->dev_addr, mac);

        if (!is_valid_ether_addr(dev->dev_addr))
                eth_hw_addr_random(dev);

        nb8800_update_mac_addr(dev);

        netif_carrier_off(dev);

        ret = register_netdev(dev);
        if (ret) {
                netdev_err(dev, "failed to register netdev\n");
                goto err_free_dma;
        }

        netif_napi_add(dev, &priv->napi, nb8800_poll, NAPI_POLL_WEIGHT);

        netdev_info(dev, "MAC address %pM\n", dev->dev_addr);

        return 0;

err_free_dma:
        nb8800_dma_free(dev);
err_deregister_fixed_link:
        if (of_phy_is_fixed_link(pdev->dev.of_node))
                of_phy_deregister_fixed_link(pdev->dev.of_node);
err_free_bus:
        of_node_put(priv->phy_node);
        mdiobus_unregister(bus);
err_disable_clk:
        clk_disable_unprepare(priv->clk);
err_free_dev:
        free_netdev(dev);

        return ret;
}

static int nb8800_remove(struct platform_device *pdev)
{
        struct net_device *ndev = platform_get_drvdata(pdev);
        struct nb8800_priv *priv = netdev_priv(ndev);

        unregister_netdev(ndev);
        if (of_phy_is_fixed_link(pdev->dev.of_node))
                of_phy_deregister_fixed_link(pdev->dev.of_node);
        of_node_put(priv->phy_node);

        mdiobus_unregister(priv->mii_bus);

        clk_disable_unprepare(priv->clk);

        nb8800_dma_free(ndev);
        free_netdev(ndev);

        return 0;
}

static struct platform_driver nb8800_driver = {
        .driver = {
                .name           = "nb8800",
                .of_match_table = nb8800_dt_ids,
        },
        .probe  = nb8800_probe,
        .remove = nb8800_remove,
};

module_platform_driver(nb8800_driver);

MODULE_DESCRIPTION("Aurora AU-NB8800 Ethernet driver");
MODULE_AUTHOR("Mans Rullgard <mans@mansr.com>");
MODULE_LICENSE("GPL");