/*
 * linux/drivers/net/ethernet/ethoc.c
 *
 * Copyright (C) 2007-2008 Avionic Design Development GmbH
 * Copyright (C) 2008-2009 Avionic Design GmbH
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Written by Thierry Reding <thierry.reding@avionic-design.de>
 */

#include <linux/dma-mapping.h>
#include <linux/etherdevice.h>
#include <linux/crc32.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/mii.h>
#include <linux/phy.h>
#include <linux/platform_device.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/module.h>
#include <net/ethoc.h>

static int buffer_size = 0x8000; /* 32 KBytes */
module_param(buffer_size, int, 0);
MODULE_PARM_DESC(buffer_size, "DMA buffer allocation size");

/* register offsets */
#define MODER           0x00
#define INT_SOURCE      0x04
#define INT_MASK        0x08
#define IPGT            0x0c
#define IPGR1           0x10
#define IPGR2           0x14
#define PACKETLEN       0x18
#define COLLCONF        0x1c
#define TX_BD_NUM       0x20
#define CTRLMODER       0x24
#define MIIMODER        0x28
#define MIICOMMAND      0x2c
#define MIIADDRESS      0x30
#define MIITX_DATA      0x34
#define MIIRX_DATA      0x38
#define MIISTATUS       0x3c
#define MAC_ADDR0       0x40
#define MAC_ADDR1       0x44
#define ETH_HASH0       0x48
#define ETH_HASH1       0x4c
#define ETH_TXCTRL      0x50

/* mode register */
#define MODER_RXEN      (1 <<  0) /* receive enable */
#define MODER_TXEN      (1 <<  1) /* transmit enable */
#define MODER_NOPRE     (1 <<  2) /* no preamble */
#define MODER_BRO       (1 <<  3) /* broadcast address */
#define MODER_IAM       (1 <<  4) /* individual address mode */
#define MODER_PRO       (1 <<  5) /* promiscuous mode */
#define MODER_IFG       (1 <<  6) /* interframe gap for incoming frames */
#define MODER_LOOP      (1 <<  7) /* loopback */
#define MODER_NBO       (1 <<  8) /* no back-off */
#define MODER_EDE       (1 <<  9) /* excess defer enable */
#define MODER_FULLD     (1 << 10) /* full duplex */
#define MODER_RESET     (1 << 11) /* FIXME: reset (undocumented) */
#define MODER_DCRC      (1 << 12) /* delayed CRC enable */
#define MODER_CRC       (1 << 13) /* CRC enable */
#define MODER_HUGE      (1 << 14) /* huge packets enable */
#define MODER_PAD       (1 << 15) /* padding enabled */
#define MODER_RSM       (1 << 16) /* receive small packets */

/* interrupt source and mask registers */
#define INT_MASK_TXF    (1 << 0) /* transmit frame */
#define INT_MASK_TXE    (1 << 1) /* transmit error */
#define INT_MASK_RXF    (1 << 2) /* receive frame */
#define INT_MASK_RXE    (1 << 3) /* receive error */
#define INT_MASK_BUSY   (1 << 4)
#define INT_MASK_TXC    (1 << 5) /* transmit control frame */
#define INT_MASK_RXC    (1 << 6) /* receive control frame */

#define INT_MASK_TX     (INT_MASK_TXF | INT_MASK_TXE)
#define INT_MASK_RX     (INT_MASK_RXF | INT_MASK_RXE)

#define INT_MASK_ALL ( \
                INT_MASK_TXF | INT_MASK_TXE | \
                INT_MASK_RXF | INT_MASK_RXE | \
                INT_MASK_TXC | INT_MASK_RXC | \
                INT_MASK_BUSY \
        )

/* packet length register */
#define PACKETLEN_MIN(min)              (((min) & 0xffff) << 16)
#define PACKETLEN_MAX(max)              (((max) & 0xffff) <<  0)
#define PACKETLEN_MIN_MAX(min, max)     (PACKETLEN_MIN(min) | \
                                        PACKETLEN_MAX(max))

/* transmit buffer number register */
#define TX_BD_NUM_VAL(x)        (((x) <= 0x80) ? (x) : 0x80)

/* control module mode register */
#define CTRLMODER_PASSALL       (1 << 0) /* pass all receive frames */
#define CTRLMODER_RXFLOW        (1 << 1) /* receive control flow */
#define CTRLMODER_TXFLOW        (1 << 2) /* transmit control flow */

/* MII mode register */
#define MIIMODER_CLKDIV(x)      ((x) & 0xfe) /* needs to be an even number */
#define MIIMODER_NOPRE          (1 << 8) /* no preamble */

/* MII command register */
#define MIICOMMAND_SCAN         (1 << 0) /* scan status */
#define MIICOMMAND_READ         (1 << 1) /* read status */
#define MIICOMMAND_WRITE        (1 << 2) /* write control data */

/* MII address register */
#define MIIADDRESS_FIAD(x)              (((x) & 0x1f) << 0)
#define MIIADDRESS_RGAD(x)              (((x) & 0x1f) << 8)
#define MIIADDRESS_ADDR(phy, reg)       (MIIADDRESS_FIAD(phy) | \
                                        MIIADDRESS_RGAD(reg))

/* MII transmit data register */
#define MIITX_DATA_VAL(x)       ((x) & 0xffff)

/* MII receive data register */
#define MIIRX_DATA_VAL(x)       ((x) & 0xffff)

/* MII status register */
#define MIISTATUS_LINKFAIL      (1 << 0)
#define MIISTATUS_BUSY          (1 << 1)
#define MIISTATUS_INVALID       (1 << 2)

/* TX buffer descriptor */
#define TX_BD_CS                (1 <<  0) /* carrier sense lost */
#define TX_BD_DF                (1 <<  1) /* defer indication */
#define TX_BD_LC                (1 <<  2) /* late collision */
#define TX_BD_RL                (1 <<  3) /* retransmission limit */
#define TX_BD_RETRY_MASK        (0x00f0)
#define TX_BD_RETRY(x)          (((x) & 0x00f0) >>  4)
#define TX_BD_UR                (1 <<  8) /* transmitter underrun */
#define TX_BD_CRC               (1 << 11) /* TX CRC enable */
#define TX_BD_PAD               (1 << 12) /* pad enable for short packets */
#define TX_BD_WRAP              (1 << 13)
#define TX_BD_IRQ               (1 << 14) /* interrupt request enable */
#define TX_BD_READY             (1 << 15) /* TX buffer ready */
#define TX_BD_LEN(x)            (((x) & 0xffff) << 16)
#define TX_BD_LEN_MASK          (0xffff << 16)

#define TX_BD_STATS             (TX_BD_CS | TX_BD_DF | TX_BD_LC | \
                                TX_BD_RL | TX_BD_RETRY_MASK | TX_BD_UR)

/* RX buffer descriptor */
#define RX_BD_LC        (1 <<  0) /* late collision */
#define RX_BD_CRC       (1 <<  1) /* RX CRC error */
#define RX_BD_SF        (1 <<  2) /* short frame */
#define RX_BD_TL        (1 <<  3) /* too long */
#define RX_BD_DN        (1 <<  4) /* dribble nibble */
#define RX_BD_IS        (1 <<  5) /* invalid symbol */
#define RX_BD_OR        (1 <<  6) /* receiver overrun */
#define RX_BD_MISS      (1 <<  7)
#define RX_BD_CF        (1 <<  8) /* control frame */
#define RX_BD_WRAP      (1 << 13)
#define RX_BD_IRQ       (1 << 14) /* interrupt request enable */
#define RX_BD_EMPTY     (1 << 15)
#define RX_BD_LEN(x)    (((x) & 0xffff) << 16)

#define RX_BD_STATS     (RX_BD_LC | RX_BD_CRC | RX_BD_SF | RX_BD_TL | \
                        RX_BD_DN | RX_BD_IS | RX_BD_OR | RX_BD_MISS)

#define ETHOC_BUFSIZ            1536
#define ETHOC_ZLEN              64
#define ETHOC_BD_BASE           0x400
#define ETHOC_TIMEOUT           (HZ / 2)
#define ETHOC_MII_TIMEOUT       (1 + (HZ / 5))

/**
 * struct ethoc - driver-private device structure
 * @iobase:     pointer to I/O memory region
 * @membase:    pointer to buffer memory region
 * @dma_alloc:  dma allocated buffer size
 * @io_region_size:     I/O memory region size
 * @num_tx:     number of send buffers
 * @cur_tx:     last send buffer written
 * @dty_tx:     last buffer actually sent
 * @num_rx:     number of receive buffers
 * @cur_rx:     current receive buffer
 * @vma:        pointer to array of virtual memory addresses for buffers
 * @netdev:     pointer to network device structure
 * @napi:       NAPI structure
 * @msg_enable: device state flags
 * @lock:       device lock
 * @phy:        attached PHY
 * @mdio:       MDIO bus for PHY access
 * @phy_id:     address of attached PHY
 */
struct ethoc {
        void __iomem *iobase;
        void __iomem *membase;
        int dma_alloc;
        resource_size_t io_region_size;

        unsigned int num_tx;
        unsigned int cur_tx;
        unsigned int dty_tx;

        unsigned int num_rx;
        unsigned int cur_rx;

        void **vma;

        struct net_device *netdev;
        struct napi_struct napi;
        u32 msg_enable;

        spinlock_t lock;

        struct phy_device *phy;
        struct mii_bus *mdio;
        s8 phy_id;
};

/**
 * struct ethoc_bd - buffer descriptor
 * @stat:       buffer statistics
 * @addr:       physical memory address
 */
struct ethoc_bd {
        u32 stat;
        u32 addr;
};

static inline u32 ethoc_read(struct ethoc *dev, loff_t offset)
{
        return ioread32(dev->iobase + offset);
}

static inline void ethoc_write(struct ethoc *dev, loff_t offset, u32 data)
{
        iowrite32(data, dev->iobase + offset);
}

static inline void ethoc_read_bd(struct ethoc *dev, int index,
                struct ethoc_bd *bd)
{
        loff_t offset = ETHOC_BD_BASE + (index * sizeof(struct ethoc_bd));
        bd->stat = ethoc_read(dev, offset + 0);
        bd->addr = ethoc_read(dev, offset + 4);
}

static inline void ethoc_write_bd(struct ethoc *dev, int index,
                const struct ethoc_bd *bd)
{
        loff_t offset = ETHOC_BD_BASE + (index * sizeof(struct ethoc_bd));
        ethoc_write(dev, offset + 0, bd->stat);
        ethoc_write(dev, offset + 4, bd->addr);
}

static inline void ethoc_enable_irq(struct ethoc *dev, u32 mask)
{
        u32 imask = ethoc_read(dev, INT_MASK);
        imask |= mask;
        ethoc_write(dev, INT_MASK, imask);
}

static inline void ethoc_disable_irq(struct ethoc *dev, u32 mask)
{
        u32 imask = ethoc_read(dev, INT_MASK);
        imask &= ~mask;
        ethoc_write(dev, INT_MASK, imask);
}

static inline void ethoc_ack_irq(struct ethoc *dev, u32 mask)
{
        ethoc_write(dev, INT_SOURCE, mask);
}

static inline void ethoc_enable_rx_and_tx(struct ethoc *dev)
{
        u32 mode = ethoc_read(dev, MODER);
        mode |= MODER_RXEN | MODER_TXEN;
        ethoc_write(dev, MODER, mode);
}

static inline void ethoc_disable_rx_and_tx(struct ethoc *dev)
{
        u32 mode = ethoc_read(dev, MODER);
        mode &= ~(MODER_RXEN | MODER_TXEN);
        ethoc_write(dev, MODER, mode);
}

static int ethoc_init_ring(struct ethoc *dev, unsigned long mem_start)
{
        struct ethoc_bd bd;
        int i;
        void *vma;

        dev->cur_tx = 0;
        dev->dty_tx = 0;
        dev->cur_rx = 0;

        ethoc_write(dev, TX_BD_NUM, dev->num_tx);

        /* setup transmission buffers */
        bd.addr = mem_start;
        bd.stat = TX_BD_IRQ | TX_BD_CRC;
        vma = dev->membase;

        for (i = 0; i < dev->num_tx; i++) {
                if (i == dev->num_tx - 1)
                        bd.stat |= TX_BD_WRAP;

                ethoc_write_bd(dev, i, &bd);
                bd.addr += ETHOC_BUFSIZ;

                dev->vma[i] = vma;
                vma += ETHOC_BUFSIZ;
        }

        bd.stat = RX_BD_EMPTY | RX_BD_IRQ;

        for (i = 0; i < dev->num_rx; i++) {
                if (i == dev->num_rx - 1)
                        bd.stat |= RX_BD_WRAP;

                ethoc_write_bd(dev, dev->num_tx + i, &bd);
                bd.addr += ETHOC_BUFSIZ;

                dev->vma[dev->num_tx + i] = vma;
                vma += ETHOC_BUFSIZ;
        }

        return 0;
}

static int ethoc_reset(struct ethoc *dev)
{
        u32 mode;

        /* TODO: reset controller? */

        ethoc_disable_rx_and_tx(dev);

        /* TODO: setup registers */

        /* enable FCS generation and automatic padding */
        mode = ethoc_read(dev, MODER);
        mode |= MODER_CRC | MODER_PAD;
        ethoc_write(dev, MODER, mode);

        /* set full-duplex mode */
        mode = ethoc_read(dev, MODER);
        mode |= MODER_FULLD;
        ethoc_write(dev, MODER, mode);
        ethoc_write(dev, IPGT, 0x15);

        ethoc_ack_irq(dev, INT_MASK_ALL);
        ethoc_enable_irq(dev, INT_MASK_ALL);
        ethoc_enable_rx_and_tx(dev);
        return 0;
}

static unsigned int ethoc_update_rx_stats(struct ethoc *dev,
                struct ethoc_bd *bd)
{
        struct net_device *netdev = dev->netdev;
        unsigned int ret = 0;

        if (bd->stat & RX_BD_TL) {
                dev_err(&netdev->dev, "RX: frame too long\n");
                netdev->stats.rx_length_errors++;
                ret++;
        }

        if (bd->stat & RX_BD_SF) {
                dev_err(&netdev->dev, "RX: frame too short\n");
                netdev->stats.rx_length_errors++;
                ret++;
        }

        if (bd->stat & RX_BD_DN) {
                dev_err(&netdev->dev, "RX: dribble nibble\n");
                netdev->stats.rx_frame_errors++;
        }

        if (bd->stat & RX_BD_CRC) {
                dev_err(&netdev->dev, "RX: wrong CRC\n");
                netdev->stats.rx_crc_errors++;
                ret++;
        }

        if (bd->stat & RX_BD_OR) {
                dev_err(&netdev->dev, "RX: overrun\n");
                netdev->stats.rx_over_errors++;
                ret++;
        }

        if (bd->stat & RX_BD_MISS)
                netdev->stats.rx_missed_errors++;

        if (bd->stat & RX_BD_LC) {
                dev_err(&netdev->dev, "RX: late collision\n");
                netdev->stats.collisions++;
                ret++;
        }

        return ret;
}

static int ethoc_rx(struct net_device *dev, int limit)
{
        struct ethoc *priv = netdev_priv(dev);
        int count;

        for (count = 0; count < limit; ++count) {
                unsigned int entry;
                struct ethoc_bd bd;

                entry = priv->num_tx + priv->cur_rx;
                ethoc_read_bd(priv, entry, &bd);
                if (bd.stat & RX_BD_EMPTY) {
                        ethoc_ack_irq(priv, INT_MASK_RX);
                        /* If packet (interrupt) came in between checking
                         * BD_EMTPY and clearing the interrupt source, then we
                         * risk missing the packet as the RX interrupt won't
                         * trigger right away when we reenable it; hence, check
                         * BD_EMTPY here again to make sure there isn't such a
                         * packet waiting for us...
                         */
                        ethoc_read_bd(priv, entry, &bd);
                        if (bd.stat & RX_BD_EMPTY)
                                break;
                }

                if (ethoc_update_rx_stats(priv, &bd) == 0) {
                        int size = bd.stat >> 16;
                        struct sk_buff *skb;

                        size -= 4; /* strip the CRC */
                        skb = netdev_alloc_skb_ip_align(dev, size);

                        if (likely(skb)) {
                                void *src = priv->vma[entry];
                                memcpy_fromio(skb_put(skb, size), src, size);
                                skb->protocol = eth_type_trans(skb, dev);
                                dev->stats.rx_packets++;
                                dev->stats.rx_bytes += size;
                                netif_receive_skb(skb);
                        } else {
                                if (net_ratelimit())
                                        dev_warn(&dev->dev,
                                            "low on memory - packet dropped\n");

                                dev->stats.rx_dropped++;
                                break;
                        }
                }

                /* clear the buffer descriptor so it can be reused */
                bd.stat &= ~RX_BD_STATS;
                bd.stat |=  RX_BD_EMPTY;
                ethoc_write_bd(priv, entry, &bd);
                if (++priv->cur_rx == priv->num_rx)
                        priv->cur_rx = 0;
        }

        return count;
}

static void ethoc_update_tx_stats(struct ethoc *dev, struct ethoc_bd *bd)
{
        struct net_device *netdev = dev->netdev;

        if (bd->stat & TX_BD_LC) {
                dev_err(&netdev->dev, "TX: late collision\n");
                netdev->stats.tx_window_errors++;
        }

        if (bd->stat & TX_BD_RL) {
                dev_err(&netdev->dev, "TX: retransmit limit\n");
                netdev->stats.tx_aborted_errors++;
        }

        if (bd->stat & TX_BD_UR) {
                dev_err(&netdev->dev, "TX: underrun\n");
                netdev->stats.tx_fifo_errors++;
        }

        if (bd->stat & TX_BD_CS) {
                dev_err(&netdev->dev, "TX: carrier sense lost\n");
                netdev->stats.tx_carrier_errors++;
        }

        if (bd->stat & TX_BD_STATS)
                netdev->stats.tx_errors++;

        netdev->stats.collisions += (bd->stat >> 4) & 0xf;
        netdev->stats.tx_bytes += bd->stat >> 16;
        netdev->stats.tx_packets++;
}

static int ethoc_tx(struct net_device *dev, int limit)
{
        struct ethoc *priv = netdev_priv(dev);
        int count;
        struct ethoc_bd bd;

        for (count = 0; count < limit; ++count) {
                unsigned int entry;

                entry = priv->dty_tx & (priv->num_tx-1);

                ethoc_read_bd(priv, entry, &bd);

                if (bd.stat & TX_BD_READY || (priv->dty_tx == priv->cur_tx)) {
                        ethoc_ack_irq(priv, INT_MASK_TX);
                        /* If interrupt came in between reading in the BD
                         * and clearing the interrupt source, then we risk
                         * missing the event as the TX interrupt won't trigger
                         * right away when we reenable it; hence, check
                         * BD_EMPTY here again to make sure there isn't such an
                         * event pending...
                         */
                        ethoc_read_bd(priv, entry, &bd);
                        if (bd.stat & TX_BD_READY ||
                            (priv->dty_tx == priv->cur_tx))
                                break;
                }

                ethoc_update_tx_stats(priv, &bd);
                priv->dty_tx++;
        }

        if ((priv->cur_tx - priv->dty_tx) <= (priv->num_tx / 2))
                netif_wake_queue(dev);

        return count;
}

static irqreturn_t ethoc_interrupt(int irq, void *dev_id)
{
        struct net_device *dev = dev_id;
        struct ethoc *priv = netdev_priv(dev);
        u32 pending;
        u32 mask;

        /* Figure out what triggered the interrupt...
         * The tricky bit here is that the interrupt source bits get
         * set in INT_SOURCE for an event regardless of whether that
         * event is masked or not.  Thus, in order to figure out what
         * triggered the interrupt, we need to remove the sources
         * for all events that are currently masked.  This behaviour
         * is not particularly well documented but reasonable...
         */
        mask = ethoc_read(priv, INT_MASK);
        pending = ethoc_read(priv, INT_SOURCE);
        pending &= mask;

        if (unlikely(pending == 0))
                return IRQ_NONE;

        ethoc_ack_irq(priv, pending);

        /* We always handle the dropped packet interrupt */
        if (pending & INT_MASK_BUSY) {
                dev_err(&dev->dev, "packet dropped\n");
                dev->stats.rx_dropped++;
        }

        /* Handle receive/transmit event by switching to polling */
        if (pending & (INT_MASK_TX | INT_MASK_RX)) {
                ethoc_disable_irq(priv, INT_MASK_TX | INT_MASK_RX);
                napi_schedule(&priv->napi);
        }

        return IRQ_HANDLED;
}

static int ethoc_get_mac_address(struct net_device *dev, void *addr)
{
        struct ethoc *priv = netdev_priv(dev);
        u8 *mac = (u8 *)addr;
        u32 reg;

        reg = ethoc_read(priv, MAC_ADDR0);
        mac[2] = (reg >> 24) & 0xff;
        mac[3] = (reg >> 16) & 0xff;
        mac[4] = (reg >>  8) & 0xff;
        mac[5] = (reg >>  0) & 0xff;

        reg = ethoc_read(priv, MAC_ADDR1);
        mac[0] = (reg >>  8) & 0xff;
        mac[1] = (reg >>  0) & 0xff;

        return 0;
}

static int ethoc_poll(struct napi_struct *napi, int budget)
{
        struct ethoc *priv = container_of(napi, struct ethoc, napi);
        int rx_work_done = 0;
        int tx_work_done = 0;

        rx_work_done = ethoc_rx(priv->netdev, budget);
        tx_work_done = ethoc_tx(priv->netdev, budget);

        if (rx_work_done < budget && tx_work_done < budget) {
                napi_complete(napi);
                ethoc_enable_irq(priv, INT_MASK_TX | INT_MASK_RX);
        }

        return rx_work_done;
}

static int ethoc_mdio_read(struct mii_bus *bus, int phy, int reg)
{
        struct ethoc *priv = bus->priv;
        int i;

        ethoc_write(priv, MIIADDRESS, MIIADDRESS_ADDR(phy, reg));
        ethoc_write(priv, MIICOMMAND, MIICOMMAND_READ);

        for (i = 0; i < 5; i++) {
                u32 status = ethoc_read(priv, MIISTATUS);
                if (!(status & MIISTATUS_BUSY)) {
                        u32 data = ethoc_read(priv, MIIRX_DATA);
                        /* reset MII command register */
                        ethoc_write(priv, MIICOMMAND, 0);
                        return data;
                }
                usleep_range(100, 200);
        }

        return -EBUSY;
}

static int ethoc_mdio_write(struct mii_bus *bus, int phy, int reg, u16 val)
{
        struct ethoc *priv = bus->priv;
        int i;

        ethoc_write(priv, MIIADDRESS, MIIADDRESS_ADDR(phy, reg));
        ethoc_write(priv, MIITX_DATA, val);
        ethoc_write(priv, MIICOMMAND, MIICOMMAND_WRITE);

        for (i = 0; i < 5; i++) {
                u32 stat = ethoc_read(priv, MIISTATUS);
                if (!(stat & MIISTATUS_BUSY)) {
                        /* reset MII command register */
                        ethoc_write(priv, MIICOMMAND, 0);
                        return 0;
                }
                usleep_range(100, 200);
        }

        return -EBUSY;
}

static int ethoc_mdio_reset(struct mii_bus *bus)
{
        return 0;
}

static void ethoc_mdio_poll(struct net_device *dev)
{
}

static int ethoc_mdio_probe(struct net_device *dev)
{
        struct ethoc *priv = netdev_priv(dev);
        struct phy_device *phy;
        int err;

        if (priv->phy_id != -1)
                phy = mdiobus_get_phy(priv->mdio, priv->phy_id);
        else
                phy = phy_find_first(priv->mdio);

        if (!phy) {
                dev_err(&dev->dev, "no PHY found\n");
                return -ENXIO;
        }

        err = phy_connect_direct(dev, phy, ethoc_mdio_poll,
                                 PHY_INTERFACE_MODE_GMII);
        if (err) {
                dev_err(&dev->dev, "could not attach to PHY\n");
                return err;
        }

        priv->phy = phy;
        return 0;
}

static int ethoc_open(struct net_device *dev)
{
        struct ethoc *priv = netdev_priv(dev);
        int ret;

        ret = request_irq(dev->irq, ethoc_interrupt, IRQF_SHARED,
                        dev->name, dev);
        if (ret)
                return ret;

        ethoc_init_ring(priv, dev->mem_start);
        ethoc_reset(priv);

        if (netif_queue_stopped(dev)) {
                dev_dbg(&dev->dev, " resuming queue\n");
                netif_wake_queue(dev);
        } else {
                dev_dbg(&dev->dev, " starting queue\n");
                netif_start_queue(dev);
        }

        phy_start(priv->phy);
        napi_enable(&priv->napi);

        if (netif_msg_ifup(priv)) {
                dev_info(&dev->dev, "I/O: %08lx Memory: %08lx-%08lx\n",
                                dev->base_addr, dev->mem_start, dev->mem_end);
        }

        return 0;
}

static int ethoc_stop(struct net_device *dev)
{
        struct ethoc *priv = netdev_priv(dev);

        napi_disable(&priv->napi);

        if (priv->phy)
                phy_stop(priv->phy);

        ethoc_disable_rx_and_tx(priv);
        free_irq(dev->irq, dev);

        if (!netif_queue_stopped(dev))
                netif_stop_queue(dev);

        return 0;
}

static int ethoc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
        struct ethoc *priv = netdev_priv(dev);
        struct mii_ioctl_data *mdio = if_mii(ifr);
        struct phy_device *phy = NULL;

        if (!netif_running(dev))
                return -EINVAL;

        if (cmd != SIOCGMIIPHY) {
                if (mdio->phy_id >= PHY_MAX_ADDR)
                        return -ERANGE;

                phy = mdiobus_get_phy(priv->mdio, mdio->phy_id);
                if (!phy)
                        return -ENODEV;
        } else {
                phy = priv->phy;
        }

        return phy_mii_ioctl(phy, ifr, cmd);
}

static int ethoc_config(struct net_device *dev, struct ifmap *map)
{
        return -ENOSYS;
}

static void ethoc_do_set_mac_address(struct net_device *dev)
{
        struct ethoc *priv = netdev_priv(dev);
        unsigned char *mac = dev->dev_addr;

        ethoc_write(priv, MAC_ADDR0, (mac[2] << 24) | (mac[3] << 16) |
                                     (mac[4] <<  8) | (mac[5] <<  0));
        ethoc_write(priv, MAC_ADDR1, (mac[0] <<  8) | (mac[1] <<  0));
}

static int ethoc_set_mac_address(struct net_device *dev, void *p)
{
        const struct sockaddr *addr = p;

        if (!is_valid_ether_addr(addr->sa_data))
                return -EADDRNOTAVAIL;
        memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
        ethoc_do_set_mac_address(dev);
        return 0;
}

static void ethoc_set_multicast_list(struct net_device *dev)
{
        struct ethoc *priv = netdev_priv(dev);
        u32 mode = ethoc_read(priv, MODER);
        struct netdev_hw_addr *ha;
        u32 hash[2] = { 0, 0 };

        /* set loopback mode if requested */
        if (dev->flags & IFF_LOOPBACK)
                mode |=  MODER_LOOP;
        else
                mode &= ~MODER_LOOP;

        /* receive broadcast frames if requested */
        if (dev->flags & IFF_BROADCAST)
                mode &= ~MODER_BRO;
        else
                mode |=  MODER_BRO;

        /* enable promiscuous mode if requested */
        if (dev->flags & IFF_PROMISC)
                mode |=  MODER_PRO;
        else
                mode &= ~MODER_PRO;

        ethoc_write(priv, MODER, mode);

        /* receive multicast frames */
        if (dev->flags & IFF_ALLMULTI) {
                hash[0] = 0xffffffff;
                hash[1] = 0xffffffff;
        } else {
                netdev_for_each_mc_addr(ha, dev) {
                        u32 crc = ether_crc(ETH_ALEN, ha->addr);
                        int bit = (crc >> 26) & 0x3f;
                        hash[bit >> 5] |= 1 << (bit & 0x1f);
                }
        }

        ethoc_write(priv, ETH_HASH0, hash[0]);
        ethoc_write(priv, ETH_HASH1, hash[1]);
}

static int ethoc_change_mtu(struct net_device *dev, int new_mtu)
{
        return -ENOSYS;
}

static void ethoc_tx_timeout(struct net_device *dev)
{
        struct ethoc *priv = netdev_priv(dev);
        u32 pending = ethoc_read(priv, INT_SOURCE);
        if (likely(pending))
                ethoc_interrupt(dev->irq, dev);
}

static netdev_tx_t ethoc_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct ethoc *priv = netdev_priv(dev);
        struct ethoc_bd bd;
        unsigned int entry;
        void *dest;

        if (unlikely(skb->len > ETHOC_BUFSIZ)) {
                dev->stats.tx_errors++;
                goto out;
        }

        entry = priv->cur_tx % priv->num_tx;
        spin_lock_irq(&priv->lock);
        priv->cur_tx++;

        ethoc_read_bd(priv, entry, &bd);
        if (unlikely(skb->len < ETHOC_ZLEN))
                bd.stat |=  TX_BD_PAD;
        else
                bd.stat &= ~TX_BD_PAD;

        dest = priv->vma[entry];
        memcpy_toio(dest, skb->data, skb->len);

        bd.stat &= ~(TX_BD_STATS | TX_BD_LEN_MASK);
        bd.stat |= TX_BD_LEN(skb->len);
        ethoc_write_bd(priv, entry, &bd);

        bd.stat |= TX_BD_READY;
        ethoc_write_bd(priv, entry, &bd);

        if (priv->cur_tx == (priv->dty_tx + priv->num_tx)) {
                dev_dbg(&dev->dev, "stopping queue\n");
                netif_stop_queue(dev);
        }

        spin_unlock_irq(&priv->lock);
        skb_tx_timestamp(skb);
out:
        dev_kfree_skb(skb);
        return NETDEV_TX_OK;
}

static const struct net_device_ops ethoc_netdev_ops = {
        .ndo_open = ethoc_open,
        .ndo_stop = ethoc_stop,
        .ndo_do_ioctl = ethoc_ioctl,
        .ndo_set_config = ethoc_config,
        .ndo_set_mac_address = ethoc_set_mac_address,
        .ndo_set_rx_mode = ethoc_set_multicast_list,
        .ndo_change_mtu_rh74 = ethoc_change_mtu,
        .ndo_tx_timeout = ethoc_tx_timeout,
        .ndo_start_xmit = ethoc_start_xmit,
};

/**
 * ethoc_probe - initialize OpenCores ethernet MAC
 * pdev:        platform device
 */
static int ethoc_probe(struct platform_device *pdev)
{
        struct net_device *netdev = NULL;
        struct resource *res = NULL;
        struct resource *mmio = NULL;
        struct resource *mem = NULL;
        struct ethoc *priv = NULL;
        unsigned int phy;
        int num_bd;
        int ret = 0;
        bool random_mac = false;

        /* allocate networking device */
        netdev = alloc_etherdev(sizeof(struct ethoc));
        if (!netdev) {
                ret = -ENOMEM;
                goto out;
        }

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

        /* obtain I/O memory space */
        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res) {
                dev_err(&pdev->dev, "cannot obtain I/O memory space\n");
                ret = -ENXIO;
                goto free;
        }

        mmio = devm_request_mem_region(&pdev->dev, res->start,
                        resource_size(res), res->name);
        if (!mmio) {
                dev_err(&pdev->dev, "cannot request I/O memory space\n");
                ret = -ENXIO;
                goto free;
        }

        netdev->base_addr = mmio->start;

        /* obtain buffer memory space */
        res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
        if (res) {
                mem = devm_request_mem_region(&pdev->dev, res->start,
                        resource_size(res), res->name);
                if (!mem) {
                        dev_err(&pdev->dev, "cannot request memory space\n");
                        ret = -ENXIO;
                        goto free;
                }

                netdev->mem_start = mem->start;
                netdev->mem_end   = mem->end;
        }


        /* obtain device IRQ number */
        res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
        if (!res) {
                dev_err(&pdev->dev, "cannot obtain IRQ\n");
                ret = -ENXIO;
                goto free;
        }

        netdev->irq = res->start;

        /* setup driver-private data */
        priv = netdev_priv(netdev);
        priv->netdev = netdev;
        priv->dma_alloc = 0;
        priv->io_region_size = resource_size(mmio);

        priv->iobase = devm_ioremap_nocache(&pdev->dev, netdev->base_addr,
                        resource_size(mmio));
        if (!priv->iobase) {
                dev_err(&pdev->dev, "cannot remap I/O memory space\n");
                ret = -ENXIO;
                goto error;
        }

        if (netdev->mem_end) {
                priv->membase = devm_ioremap_nocache(&pdev->dev,
                        netdev->mem_start, resource_size(mem));
                if (!priv->membase) {
                        dev_err(&pdev->dev, "cannot remap memory space\n");
                        ret = -ENXIO;
                        goto error;
                }
        } else {
                /* Allocate buffer memory */
                priv->membase = dmam_alloc_coherent(&pdev->dev,
                        buffer_size, (void *)&netdev->mem_start,

                        GFP_KERNEL);
                if (!priv->membase) {
                        dev_err(&pdev->dev, "cannot allocate %dB buffer\n",
                                buffer_size);
                        ret = -ENOMEM;
                        goto error;
                }
                netdev->mem_end = netdev->mem_start + buffer_size;
                priv->dma_alloc = buffer_size;
        }

        /* calculate the number of TX/RX buffers, maximum 128 supported */
        num_bd = min_t(unsigned int,
                128, (netdev->mem_end - netdev->mem_start + 1) / ETHOC_BUFSIZ);
        if (num_bd < 4) {
                ret = -ENODEV;
                goto error;
        }
        /* num_tx must be a power of two */
        priv->num_tx = rounddown_pow_of_two(num_bd >> 1);
        priv->num_rx = num_bd - priv->num_tx;

        dev_dbg(&pdev->dev, "ethoc: num_tx: %d num_rx: %d\n",
                priv->num_tx, priv->num_rx);

        priv->vma = devm_kcalloc(&pdev->dev, num_bd, sizeof(void *),
                                 GFP_KERNEL);
        if (!priv->vma) {
                ret = -ENOMEM;
                goto error;
        }

        /* Allow the platform setup code to pass in a MAC address. */
        if (pdev->dev.platform_data) {
                struct ethoc_platform_data *pdata = pdev->dev.platform_data;
                memcpy(netdev->dev_addr, pdata->hwaddr, IFHWADDRLEN);
                priv->phy_id = pdata->phy_id;
        } else {
                priv->phy_id = -1;

#ifdef CONFIG_OF
                {
                const uint8_t *mac;

                mac = of_get_property(pdev->dev.of_node,
                                      "local-mac-address",
                                      NULL);
                if (mac)
                        memcpy(netdev->dev_addr, mac, IFHWADDRLEN);
                }
#endif
        }

        /* Check that the given MAC address is valid. If it isn't, read the
         * current MAC from the controller.
         */
        if (!is_valid_ether_addr(netdev->dev_addr))
                ethoc_get_mac_address(netdev, netdev->dev_addr);

        /* Check the MAC again for validity, if it still isn't choose and
         * program a random one.
         */
        if (!is_valid_ether_addr(netdev->dev_addr)) {
                eth_random_addr(netdev->dev_addr);
                random_mac = true;
        }

        ethoc_do_set_mac_address(netdev);

        if (random_mac)
                netdev->addr_assign_type = NET_ADDR_RANDOM;

        /* register MII bus */
        priv->mdio = mdiobus_alloc();
        if (!priv->mdio) {
                ret = -ENOMEM;
                goto free;
        }

        priv->mdio->name = "ethoc-mdio";
        snprintf(priv->mdio->id, MII_BUS_ID_SIZE, "%s-%d",
                        priv->mdio->name, pdev->id);
        priv->mdio->read = ethoc_mdio_read;
        priv->mdio->write = ethoc_mdio_write;
        priv->mdio->reset = ethoc_mdio_reset;
        priv->mdio->priv = priv;

        priv->mdio->irq = kmalloc(sizeof(int) * PHY_MAX_ADDR, GFP_KERNEL);
        if (!priv->mdio->irq) {
                ret = -ENOMEM;
                goto free_mdio;
        }

        for (phy = 0; phy < PHY_MAX_ADDR; phy++)
                priv->mdio->irq[phy] = PHY_POLL;

        ret = mdiobus_register(priv->mdio);
        if (ret) {
                dev_err(&netdev->dev, "failed to register MDIO bus\n");
                goto free_mdio;
        }

        ret = ethoc_mdio_probe(netdev);
        if (ret) {
                dev_err(&netdev->dev, "failed to probe MDIO bus\n");
                goto error;
        }

        ether_setup(netdev);

        /* setup the net_device structure */
        netdev->netdev_ops = &ethoc_netdev_ops;
        netdev->watchdog_timeo = ETHOC_TIMEOUT;
        netdev->features |= 0;

        /* setup NAPI */
        netif_napi_add(netdev, &priv->napi, ethoc_poll, 64);

        spin_lock_init(&priv->lock);

        ret = register_netdev(netdev);
        if (ret < 0) {
                dev_err(&netdev->dev, "failed to register interface\n");
                goto error2;
        }

        goto out;

error2:
        netif_napi_del(&priv->napi);
error:
        mdiobus_unregister(priv->mdio);
free_mdio:
        kfree(priv->mdio->irq);
        mdiobus_free(priv->mdio);
free:
        free_netdev(netdev);
out:
        return ret;
}

/**
 * ethoc_remove - shutdown OpenCores ethernet MAC
 * @pdev:       platform device
 */
static int ethoc_remove(struct platform_device *pdev)
{
        struct net_device *netdev = platform_get_drvdata(pdev);
        struct ethoc *priv = netdev_priv(netdev);

        platform_set_drvdata(pdev, NULL);

        if (netdev) {
                netif_napi_del(&priv->napi);
                phy_disconnect(priv->phy);
                priv->phy = NULL;

                if (priv->mdio) {
                        mdiobus_unregister(priv->mdio);
                        kfree(priv->mdio->irq);
                        mdiobus_free(priv->mdio);
                }
                unregister_netdev(netdev);
                free_netdev(netdev);
        }

        return 0;
}

#ifdef CONFIG_PM
static int ethoc_suspend(struct platform_device *pdev, pm_message_t state)
{
        return -ENOSYS;
}

static int ethoc_resume(struct platform_device *pdev)
{
        return -ENOSYS;
}
#else
# define ethoc_suspend NULL
# define ethoc_resume  NULL
#endif

static struct of_device_id ethoc_match[] = {
        { .compatible = "opencores,ethoc", },
        {},
};
MODULE_DEVICE_TABLE(of, ethoc_match);

static struct platform_driver ethoc_driver = {
        .probe   = ethoc_probe,
        .remove  = ethoc_remove,
        .suspend = ethoc_suspend,
        .resume  = ethoc_resume,
        .driver  = {
                .name = "ethoc",
                .owner = THIS_MODULE,
                .of_match_table = ethoc_match,
        },
};

module_platform_driver(ethoc_driver);

MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
MODULE_DESCRIPTION("OpenCores Ethernet MAC driver");
MODULE_LICENSE("GPL v2");