/*
 * Faraday FTMAC100 10/100 Ethernet
 *
 * (C) Copyright 2009-2011 Faraday Technology
 * Po-Yu Chuang <ratbert@faraday-tech.com>
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt

#include <linux/dma-mapping.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/mii.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/platform_device.h>

#include "ftmac100.h"

#define DRV_NAME        "ftmac100"
#define DRV_VERSION     "0.2"

#define RX_QUEUE_ENTRIES        128     /* must be power of 2 */
#define TX_QUEUE_ENTRIES        16      /* must be power of 2 */

#define MAX_PKT_SIZE            1518
#define RX_BUF_SIZE             2044    /* must be smaller than 0x7ff */

#if MAX_PKT_SIZE > 0x7ff
#error invalid MAX_PKT_SIZE
#endif

#if RX_BUF_SIZE > 0x7ff || RX_BUF_SIZE > PAGE_SIZE
#error invalid RX_BUF_SIZE
#endif

/******************************************************************************
 * private data
 *****************************************************************************/
struct ftmac100_descs {
        struct ftmac100_rxdes rxdes[RX_QUEUE_ENTRIES];
        struct ftmac100_txdes txdes[TX_QUEUE_ENTRIES];
};

struct ftmac100 {
        struct resource *res;
        void __iomem *base;
        int irq;

        struct ftmac100_descs *descs;
        dma_addr_t descs_dma_addr;

        unsigned int rx_pointer;
        unsigned int tx_clean_pointer;
        unsigned int tx_pointer;
        unsigned int tx_pending;

        spinlock_t tx_lock;

        struct net_device *netdev;
        struct device *dev;
        struct napi_struct napi;

        struct mii_if_info mii;
};

static int ftmac100_alloc_rx_page(struct ftmac100 *priv,
                                  struct ftmac100_rxdes *rxdes, gfp_t gfp);

/******************************************************************************
 * internal functions (hardware register access)
 *****************************************************************************/
#define INT_MASK_ALL_ENABLED    (FTMAC100_INT_RPKT_FINISH       | \
                                 FTMAC100_INT_NORXBUF           | \
                                 FTMAC100_INT_XPKT_OK           | \
                                 FTMAC100_INT_XPKT_LOST         | \
                                 FTMAC100_INT_RPKT_LOST         | \
                                 FTMAC100_INT_AHB_ERR           | \
                                 FTMAC100_INT_PHYSTS_CHG)

#define INT_MASK_ALL_DISABLED   0

static void ftmac100_enable_all_int(struct ftmac100 *priv)
{
        iowrite32(INT_MASK_ALL_ENABLED, priv->base + FTMAC100_OFFSET_IMR);
}

static void ftmac100_disable_all_int(struct ftmac100 *priv)
{
        iowrite32(INT_MASK_ALL_DISABLED, priv->base + FTMAC100_OFFSET_IMR);
}

static void ftmac100_set_rx_ring_base(struct ftmac100 *priv, dma_addr_t addr)
{
        iowrite32(addr, priv->base + FTMAC100_OFFSET_RXR_BADR);
}

static void ftmac100_set_tx_ring_base(struct ftmac100 *priv, dma_addr_t addr)
{
        iowrite32(addr, priv->base + FTMAC100_OFFSET_TXR_BADR);
}

static void ftmac100_txdma_start_polling(struct ftmac100 *priv)
{
        iowrite32(1, priv->base + FTMAC100_OFFSET_TXPD);
}

static int ftmac100_reset(struct ftmac100 *priv)
{
        struct net_device *netdev = priv->netdev;
        int i;

        /* NOTE: reset clears all registers */
        iowrite32(FTMAC100_MACCR_SW_RST, priv->base + FTMAC100_OFFSET_MACCR);

        for (i = 0; i < 5; i++) {
                unsigned int maccr;

                maccr = ioread32(priv->base + FTMAC100_OFFSET_MACCR);
                if (!(maccr & FTMAC100_MACCR_SW_RST)) {
                        /*
                         * FTMAC100_MACCR_SW_RST cleared does not indicate
                         * that hardware reset completed (what the f*ck).
                         * We still need to wait for a while.
                         */
                        udelay(500);
                        return 0;
                }

                udelay(1000);
        }

        netdev_err(netdev, "software reset failed\n");
        return -EIO;
}

static void ftmac100_set_mac(struct ftmac100 *priv, const unsigned char *mac)
{
        unsigned int maddr = mac[0] << 8 | mac[1];
        unsigned int laddr = mac[2] << 24 | mac[3] << 16 | mac[4] << 8 | mac[5];

        iowrite32(maddr, priv->base + FTMAC100_OFFSET_MAC_MADR);
        iowrite32(laddr, priv->base + FTMAC100_OFFSET_MAC_LADR);
}

#define MACCR_ENABLE_ALL        (FTMAC100_MACCR_XMT_EN  | \
                                 FTMAC100_MACCR_RCV_EN  | \
                                 FTMAC100_MACCR_XDMA_EN | \
                                 FTMAC100_MACCR_RDMA_EN | \
                                 FTMAC100_MACCR_CRC_APD | \
                                 FTMAC100_MACCR_FULLDUP | \
                                 FTMAC100_MACCR_RX_RUNT | \
                                 FTMAC100_MACCR_RX_BROADPKT)

static int ftmac100_start_hw(struct ftmac100 *priv)
{
        struct net_device *netdev = priv->netdev;

        if (ftmac100_reset(priv))
                return -EIO;

        /* setup ring buffer base registers */
        ftmac100_set_rx_ring_base(priv,
                                  priv->descs_dma_addr +
                                  offsetof(struct ftmac100_descs, rxdes));
        ftmac100_set_tx_ring_base(priv,
                                  priv->descs_dma_addr +
                                  offsetof(struct ftmac100_descs, txdes));

        iowrite32(FTMAC100_APTC_RXPOLL_CNT(1), priv->base + FTMAC100_OFFSET_APTC);

        ftmac100_set_mac(priv, netdev->dev_addr);

        iowrite32(MACCR_ENABLE_ALL, priv->base + FTMAC100_OFFSET_MACCR);
        return 0;
}

static void ftmac100_stop_hw(struct ftmac100 *priv)
{
        iowrite32(0, priv->base + FTMAC100_OFFSET_MACCR);
}

/******************************************************************************
 * internal functions (receive descriptor)
 *****************************************************************************/
static bool ftmac100_rxdes_first_segment(struct ftmac100_rxdes *rxdes)
{
        return rxdes->rxdes0 & cpu_to_le32(FTMAC100_RXDES0_FRS);
}

static bool ftmac100_rxdes_last_segment(struct ftmac100_rxdes *rxdes)
{
        return rxdes->rxdes0 & cpu_to_le32(FTMAC100_RXDES0_LRS);
}

static bool ftmac100_rxdes_owned_by_dma(struct ftmac100_rxdes *rxdes)
{
        return rxdes->rxdes0 & cpu_to_le32(FTMAC100_RXDES0_RXDMA_OWN);
}

static void ftmac100_rxdes_set_dma_own(struct ftmac100_rxdes *rxdes)
{
        /* clear status bits */
        rxdes->rxdes0 = cpu_to_le32(FTMAC100_RXDES0_RXDMA_OWN);
}

static bool ftmac100_rxdes_rx_error(struct ftmac100_rxdes *rxdes)
{
        return rxdes->rxdes0 & cpu_to_le32(FTMAC100_RXDES0_RX_ERR);
}

static bool ftmac100_rxdes_crc_error(struct ftmac100_rxdes *rxdes)
{
        return rxdes->rxdes0 & cpu_to_le32(FTMAC100_RXDES0_CRC_ERR);
}

static bool ftmac100_rxdes_frame_too_long(struct ftmac100_rxdes *rxdes)
{
        return rxdes->rxdes0 & cpu_to_le32(FTMAC100_RXDES0_FTL);
}

static bool ftmac100_rxdes_runt(struct ftmac100_rxdes *rxdes)
{
        return rxdes->rxdes0 & cpu_to_le32(FTMAC100_RXDES0_RUNT);
}

static bool ftmac100_rxdes_odd_nibble(struct ftmac100_rxdes *rxdes)
{
        return rxdes->rxdes0 & cpu_to_le32(FTMAC100_RXDES0_RX_ODD_NB);
}

static unsigned int ftmac100_rxdes_frame_length(struct ftmac100_rxdes *rxdes)
{
        return le32_to_cpu(rxdes->rxdes0) & FTMAC100_RXDES0_RFL;
}

static bool ftmac100_rxdes_multicast(struct ftmac100_rxdes *rxdes)
{
        return rxdes->rxdes0 & cpu_to_le32(FTMAC100_RXDES0_MULTICAST);
}

static void ftmac100_rxdes_set_buffer_size(struct ftmac100_rxdes *rxdes,
                                           unsigned int size)
{
        rxdes->rxdes1 &= cpu_to_le32(FTMAC100_RXDES1_EDORR);
        rxdes->rxdes1 |= cpu_to_le32(FTMAC100_RXDES1_RXBUF_SIZE(size));
}

static void ftmac100_rxdes_set_end_of_ring(struct ftmac100_rxdes *rxdes)
{
        rxdes->rxdes1 |= cpu_to_le32(FTMAC100_RXDES1_EDORR);
}

static void ftmac100_rxdes_set_dma_addr(struct ftmac100_rxdes *rxdes,
                                        dma_addr_t addr)
{
        rxdes->rxdes2 = cpu_to_le32(addr);
}

static dma_addr_t ftmac100_rxdes_get_dma_addr(struct ftmac100_rxdes *rxdes)
{
        return le32_to_cpu(rxdes->rxdes2);
}

/*
 * rxdes3 is not used by hardware. We use it to keep track of page.
 * Since hardware does not touch it, we can skip cpu_to_le32()/le32_to_cpu().
 */
static void ftmac100_rxdes_set_page(struct ftmac100_rxdes *rxdes, struct page *page)
{
        rxdes->rxdes3 = (unsigned int)page;
}

static struct page *ftmac100_rxdes_get_page(struct ftmac100_rxdes *rxdes)
{
        return (struct page *)rxdes->rxdes3;
}

/******************************************************************************
 * internal functions (receive)
 *****************************************************************************/
static int ftmac100_next_rx_pointer(int pointer)
{
        return (pointer + 1) & (RX_QUEUE_ENTRIES - 1);
}

static void ftmac100_rx_pointer_advance(struct ftmac100 *priv)
{
        priv->rx_pointer = ftmac100_next_rx_pointer(priv->rx_pointer);
}

static struct ftmac100_rxdes *ftmac100_current_rxdes(struct ftmac100 *priv)
{
        return &priv->descs->rxdes[priv->rx_pointer];
}

static struct ftmac100_rxdes *
ftmac100_rx_locate_first_segment(struct ftmac100 *priv)
{
        struct ftmac100_rxdes *rxdes = ftmac100_current_rxdes(priv);

        while (!ftmac100_rxdes_owned_by_dma(rxdes)) {
                if (ftmac100_rxdes_first_segment(rxdes))
                        return rxdes;

                ftmac100_rxdes_set_dma_own(rxdes);
                ftmac100_rx_pointer_advance(priv);
                rxdes = ftmac100_current_rxdes(priv);
        }

        return NULL;
}

static bool ftmac100_rx_packet_error(struct ftmac100 *priv,
                                     struct ftmac100_rxdes *rxdes)
{
        struct net_device *netdev = priv->netdev;
        bool error = false;

        if (unlikely(ftmac100_rxdes_rx_error(rxdes))) {
                if (net_ratelimit())
                        netdev_info(netdev, "rx err\n");

                netdev->stats.rx_errors++;
                error = true;
        }

        if (unlikely(ftmac100_rxdes_crc_error(rxdes))) {
                if (net_ratelimit())
                        netdev_info(netdev, "rx crc err\n");

                netdev->stats.rx_crc_errors++;
                error = true;
        }

        if (unlikely(ftmac100_rxdes_frame_too_long(rxdes))) {
                if (net_ratelimit())
                        netdev_info(netdev, "rx frame too long\n");

                netdev->stats.rx_length_errors++;
                error = true;
        } else if (unlikely(ftmac100_rxdes_runt(rxdes))) {
                if (net_ratelimit())
                        netdev_info(netdev, "rx runt\n");

                netdev->stats.rx_length_errors++;
                error = true;
        } else if (unlikely(ftmac100_rxdes_odd_nibble(rxdes))) {
                if (net_ratelimit())
                        netdev_info(netdev, "rx odd nibble\n");

                netdev->stats.rx_length_errors++;
                error = true;
        }

        return error;
}

static void ftmac100_rx_drop_packet(struct ftmac100 *priv)
{
        struct net_device *netdev = priv->netdev;
        struct ftmac100_rxdes *rxdes = ftmac100_current_rxdes(priv);
        bool done = false;

        if (net_ratelimit())
                netdev_dbg(netdev, "drop packet %p\n", rxdes);

        do {
                if (ftmac100_rxdes_last_segment(rxdes))
                        done = true;

                ftmac100_rxdes_set_dma_own(rxdes);
                ftmac100_rx_pointer_advance(priv);
                rxdes = ftmac100_current_rxdes(priv);
        } while (!done && !ftmac100_rxdes_owned_by_dma(rxdes));

        netdev->stats.rx_dropped++;
}

static bool ftmac100_rx_packet(struct ftmac100 *priv, int *processed)
{
        struct net_device *netdev = priv->netdev;
        struct ftmac100_rxdes *rxdes;
        struct sk_buff *skb;
        struct page *page;
        dma_addr_t map;
        int length;

        rxdes = ftmac100_rx_locate_first_segment(priv);
        if (!rxdes)
                return false;

        if (unlikely(ftmac100_rx_packet_error(priv, rxdes))) {
                ftmac100_rx_drop_packet(priv);
                return true;
        }

        /*
         * It is impossible to get multi-segment packets
         * because we always provide big enough receive buffers.
         */
        if (unlikely(!ftmac100_rxdes_last_segment(rxdes)))
                BUG();

        /* start processing */
        skb = netdev_alloc_skb_ip_align(netdev, 128);
        if (unlikely(!skb)) {
                if (net_ratelimit())
                        netdev_err(netdev, "rx skb alloc failed\n");

                ftmac100_rx_drop_packet(priv);
                return true;
        }

        if (unlikely(ftmac100_rxdes_multicast(rxdes)))
                netdev->stats.multicast++;

        map = ftmac100_rxdes_get_dma_addr(rxdes);
        dma_unmap_page(priv->dev, map, RX_BUF_SIZE, DMA_FROM_DEVICE);

        length = ftmac100_rxdes_frame_length(rxdes);
        page = ftmac100_rxdes_get_page(rxdes);
        skb_fill_page_desc(skb, 0, page, 0, length);
        skb->len += length;
        skb->data_len += length;

        if (length > 128) {
                skb->truesize += PAGE_SIZE;
                /* We pull the minimum amount into linear part */
                __pskb_pull_tail(skb, ETH_HLEN);
        } else {
                /* Small frames are copied into linear part to free one page */
                __pskb_pull_tail(skb, length);
        }
        ftmac100_alloc_rx_page(priv, rxdes, GFP_ATOMIC);

        ftmac100_rx_pointer_advance(priv);

        skb->protocol = eth_type_trans(skb, netdev);

        netdev->stats.rx_packets++;
        netdev->stats.rx_bytes += skb->len;

        /* push packet to protocol stack */
        netif_receive_skb(skb);

        (*processed)++;
        return true;
}

/******************************************************************************
 * internal functions (transmit descriptor)
 *****************************************************************************/
static void ftmac100_txdes_reset(struct ftmac100_txdes *txdes)
{
        /* clear all except end of ring bit */
        txdes->txdes0 = 0;
        txdes->txdes1 &= cpu_to_le32(FTMAC100_TXDES1_EDOTR);
        txdes->txdes2 = 0;
        txdes->txdes3 = 0;
}

static bool ftmac100_txdes_owned_by_dma(struct ftmac100_txdes *txdes)
{
        return txdes->txdes0 & cpu_to_le32(FTMAC100_TXDES0_TXDMA_OWN);
}

static void ftmac100_txdes_set_dma_own(struct ftmac100_txdes *txdes)
{
        /*
         * Make sure dma own bit will not be set before any other
         * descriptor fields.
         */
        wmb();
        txdes->txdes0 |= cpu_to_le32(FTMAC100_TXDES0_TXDMA_OWN);
}

static bool ftmac100_txdes_excessive_collision(struct ftmac100_txdes *txdes)
{
        return txdes->txdes0 & cpu_to_le32(FTMAC100_TXDES0_TXPKT_EXSCOL);
}

static bool ftmac100_txdes_late_collision(struct ftmac100_txdes *txdes)
{
        return txdes->txdes0 & cpu_to_le32(FTMAC100_TXDES0_TXPKT_LATECOL);
}

static void ftmac100_txdes_set_end_of_ring(struct ftmac100_txdes *txdes)
{
        txdes->txdes1 |= cpu_to_le32(FTMAC100_TXDES1_EDOTR);
}

static void ftmac100_txdes_set_first_segment(struct ftmac100_txdes *txdes)
{
        txdes->txdes1 |= cpu_to_le32(FTMAC100_TXDES1_FTS);
}

static void ftmac100_txdes_set_last_segment(struct ftmac100_txdes *txdes)
{
        txdes->txdes1 |= cpu_to_le32(FTMAC100_TXDES1_LTS);
}

static void ftmac100_txdes_set_txint(struct ftmac100_txdes *txdes)
{
        txdes->txdes1 |= cpu_to_le32(FTMAC100_TXDES1_TXIC);
}

static void ftmac100_txdes_set_buffer_size(struct ftmac100_txdes *txdes,
                                           unsigned int len)
{
        txdes->txdes1 |= cpu_to_le32(FTMAC100_TXDES1_TXBUF_SIZE(len));
}

static void ftmac100_txdes_set_dma_addr(struct ftmac100_txdes *txdes,
                                        dma_addr_t addr)
{
        txdes->txdes2 = cpu_to_le32(addr);
}

static dma_addr_t ftmac100_txdes_get_dma_addr(struct ftmac100_txdes *txdes)
{
        return le32_to_cpu(txdes->txdes2);
}

/*
 * txdes3 is not used by hardware. We use it to keep track of socket buffer.
 * Since hardware does not touch it, we can skip cpu_to_le32()/le32_to_cpu().
 */
static void ftmac100_txdes_set_skb(struct ftmac100_txdes *txdes, struct sk_buff *skb)
{
        txdes->txdes3 = (unsigned int)skb;
}

static struct sk_buff *ftmac100_txdes_get_skb(struct ftmac100_txdes *txdes)
{
        return (struct sk_buff *)txdes->txdes3;
}

/******************************************************************************
 * internal functions (transmit)
 *****************************************************************************/
static int ftmac100_next_tx_pointer(int pointer)
{
        return (pointer + 1) & (TX_QUEUE_ENTRIES - 1);
}

static void ftmac100_tx_pointer_advance(struct ftmac100 *priv)
{
        priv->tx_pointer = ftmac100_next_tx_pointer(priv->tx_pointer);
}

static void ftmac100_tx_clean_pointer_advance(struct ftmac100 *priv)
{
        priv->tx_clean_pointer = ftmac100_next_tx_pointer(priv->tx_clean_pointer);
}

static struct ftmac100_txdes *ftmac100_current_txdes(struct ftmac100 *priv)
{
        return &priv->descs->txdes[priv->tx_pointer];
}

static struct ftmac100_txdes *ftmac100_current_clean_txdes(struct ftmac100 *priv)
{
        return &priv->descs->txdes[priv->tx_clean_pointer];
}

static bool ftmac100_tx_complete_packet(struct ftmac100 *priv)
{
        struct net_device *netdev = priv->netdev;
        struct ftmac100_txdes *txdes;
        struct sk_buff *skb;
        dma_addr_t map;

        if (priv->tx_pending == 0)
                return false;

        txdes = ftmac100_current_clean_txdes(priv);

        if (ftmac100_txdes_owned_by_dma(txdes))
                return false;

        skb = ftmac100_txdes_get_skb(txdes);
        map = ftmac100_txdes_get_dma_addr(txdes);

        if (unlikely(ftmac100_txdes_excessive_collision(txdes) ||
                     ftmac100_txdes_late_collision(txdes))) {
                /*
                 * packet transmitted to ethernet lost due to late collision
                 * or excessive collision
                 */
                netdev->stats.tx_aborted_errors++;
        } else {
                netdev->stats.tx_packets++;
                netdev->stats.tx_bytes += skb->len;
        }

        dma_unmap_single(priv->dev, map, skb_headlen(skb), DMA_TO_DEVICE);
        dev_kfree_skb(skb);

        ftmac100_txdes_reset(txdes);

        ftmac100_tx_clean_pointer_advance(priv);

        spin_lock(&priv->tx_lock);
        priv->tx_pending--;
        spin_unlock(&priv->tx_lock);
        netif_wake_queue(netdev);

        return true;
}

static void ftmac100_tx_complete(struct ftmac100 *priv)
{
        while (ftmac100_tx_complete_packet(priv))
                ;
}

static int ftmac100_xmit(struct ftmac100 *priv, struct sk_buff *skb,
                         dma_addr_t map)
{
        struct net_device *netdev = priv->netdev;
        struct ftmac100_txdes *txdes;
        unsigned int len = (skb->len < ETH_ZLEN) ? ETH_ZLEN : skb->len;

        txdes = ftmac100_current_txdes(priv);
        ftmac100_tx_pointer_advance(priv);

        /* setup TX descriptor */
        ftmac100_txdes_set_skb(txdes, skb);
        ftmac100_txdes_set_dma_addr(txdes, map);

        ftmac100_txdes_set_first_segment(txdes);
        ftmac100_txdes_set_last_segment(txdes);
        ftmac100_txdes_set_txint(txdes);
        ftmac100_txdes_set_buffer_size(txdes, len);

        spin_lock(&priv->tx_lock);
        priv->tx_pending++;
        if (priv->tx_pending == TX_QUEUE_ENTRIES)
                netif_stop_queue(netdev);

        /* start transmit */
        ftmac100_txdes_set_dma_own(txdes);
        spin_unlock(&priv->tx_lock);

        ftmac100_txdma_start_polling(priv);
        return NETDEV_TX_OK;
}

/******************************************************************************
 * internal functions (buffer)
 *****************************************************************************/
static int ftmac100_alloc_rx_page(struct ftmac100 *priv,
                                  struct ftmac100_rxdes *rxdes, gfp_t gfp)
{
        struct net_device *netdev = priv->netdev;
        struct page *page;
        dma_addr_t map;

        page = alloc_page(gfp);
        if (!page) {
                if (net_ratelimit())
                        netdev_err(netdev, "failed to allocate rx page\n");
                return -ENOMEM;
        }

        map = dma_map_page(priv->dev, page, 0, RX_BUF_SIZE, DMA_FROM_DEVICE);
        if (unlikely(dma_mapping_error(priv->dev, map))) {
                if (net_ratelimit())
                        netdev_err(netdev, "failed to map rx page\n");
                __free_page(page);
                return -ENOMEM;
        }

        ftmac100_rxdes_set_page(rxdes, page);
        ftmac100_rxdes_set_dma_addr(rxdes, map);
        ftmac100_rxdes_set_buffer_size(rxdes, RX_BUF_SIZE);
        ftmac100_rxdes_set_dma_own(rxdes);
        return 0;
}

static void ftmac100_free_buffers(struct ftmac100 *priv)
{
        int i;

        for (i = 0; i < RX_QUEUE_ENTRIES; i++) {
                struct ftmac100_rxdes *rxdes = &priv->descs->rxdes[i];
                struct page *page = ftmac100_rxdes_get_page(rxdes);
                dma_addr_t map = ftmac100_rxdes_get_dma_addr(rxdes);

                if (!page)
                        continue;

                dma_unmap_page(priv->dev, map, RX_BUF_SIZE, DMA_FROM_DEVICE);
                __free_page(page);
        }

        for (i = 0; i < TX_QUEUE_ENTRIES; i++) {
                struct ftmac100_txdes *txdes = &priv->descs->txdes[i];
                struct sk_buff *skb = ftmac100_txdes_get_skb(txdes);
                dma_addr_t map = ftmac100_txdes_get_dma_addr(txdes);

                if (!skb)
                        continue;

                dma_unmap_single(priv->dev, map, skb_headlen(skb), DMA_TO_DEVICE);
                dev_kfree_skb(skb);
        }

        dma_free_coherent(priv->dev, sizeof(struct ftmac100_descs),
                          priv->descs, priv->descs_dma_addr);
}

static int ftmac100_alloc_buffers(struct ftmac100 *priv)
{
        int i;

        priv->descs = dma_zalloc_coherent(priv->dev,
                                          sizeof(struct ftmac100_descs),
                                          &priv->descs_dma_addr,
                                          GFP_KERNEL);
        if (!priv->descs)
                return -ENOMEM;

        /* initialize RX ring */
        ftmac100_rxdes_set_end_of_ring(&priv->descs->rxdes[RX_QUEUE_ENTRIES - 1]);

        for (i = 0; i < RX_QUEUE_ENTRIES; i++) {
                struct ftmac100_rxdes *rxdes = &priv->descs->rxdes[i];

                if (ftmac100_alloc_rx_page(priv, rxdes, GFP_KERNEL))
                        goto err;
        }

        /* initialize TX ring */
        ftmac100_txdes_set_end_of_ring(&priv->descs->txdes[TX_QUEUE_ENTRIES - 1]);
        return 0;

err:
        ftmac100_free_buffers(priv);
        return -ENOMEM;
}

/******************************************************************************
 * struct mii_if_info functions
 *****************************************************************************/
static int ftmac100_mdio_read(struct net_device *netdev, int phy_id, int reg)
{
        struct ftmac100 *priv = netdev_priv(netdev);
        unsigned int phycr;
        int i;

        phycr = FTMAC100_PHYCR_PHYAD(phy_id) |
                FTMAC100_PHYCR_REGAD(reg) |
                FTMAC100_PHYCR_MIIRD;

        iowrite32(phycr, priv->base + FTMAC100_OFFSET_PHYCR);

        for (i = 0; i < 10; i++) {
                phycr = ioread32(priv->base + FTMAC100_OFFSET_PHYCR);

                if ((phycr & FTMAC100_PHYCR_MIIRD) == 0)
                        return phycr & FTMAC100_PHYCR_MIIRDATA;

                udelay(100);
        }

        netdev_err(netdev, "mdio read timed out\n");
        return 0;
}

static void ftmac100_mdio_write(struct net_device *netdev, int phy_id, int reg,
                                int data)
{
        struct ftmac100 *priv = netdev_priv(netdev);
        unsigned int phycr;
        int i;

        phycr = FTMAC100_PHYCR_PHYAD(phy_id) |
                FTMAC100_PHYCR_REGAD(reg) |
                FTMAC100_PHYCR_MIIWR;

        data = FTMAC100_PHYWDATA_MIIWDATA(data);

        iowrite32(data, priv->base + FTMAC100_OFFSET_PHYWDATA);
        iowrite32(phycr, priv->base + FTMAC100_OFFSET_PHYCR);

        for (i = 0; i < 10; i++) {
                phycr = ioread32(priv->base + FTMAC100_OFFSET_PHYCR);

                if ((phycr & FTMAC100_PHYCR_MIIWR) == 0)
                        return;

                udelay(100);
        }

        netdev_err(netdev, "mdio write timed out\n");
}

/******************************************************************************
 * struct ethtool_ops functions
 *****************************************************************************/
static void ftmac100_get_drvinfo(struct net_device *netdev,
                                 struct ethtool_drvinfo *info)
{
        strlcpy(info->driver, DRV_NAME, sizeof(info->driver));
        strlcpy(info->version, DRV_VERSION, sizeof(info->version));
        strlcpy(info->bus_info, dev_name(&netdev->dev), sizeof(info->bus_info));
}

static int ftmac100_get_settings(struct net_device *netdev, struct ethtool_cmd *cmd)
{
        struct ftmac100 *priv = netdev_priv(netdev);
        return mii_ethtool_gset(&priv->mii, cmd);
}

static int ftmac100_set_settings(struct net_device *netdev, struct ethtool_cmd *cmd)
{
        struct ftmac100 *priv = netdev_priv(netdev);
        return mii_ethtool_sset(&priv->mii, cmd);
}

static int ftmac100_nway_reset(struct net_device *netdev)
{
        struct ftmac100 *priv = netdev_priv(netdev);
        return mii_nway_restart(&priv->mii);
}

static u32 ftmac100_get_link(struct net_device *netdev)
{
        struct ftmac100 *priv = netdev_priv(netdev);
        return mii_link_ok(&priv->mii);
}

static const struct ethtool_ops ftmac100_ethtool_ops = {
        .set_settings           = ftmac100_set_settings,
        .get_settings           = ftmac100_get_settings,
        .get_drvinfo            = ftmac100_get_drvinfo,
        .nway_reset             = ftmac100_nway_reset,
        .get_link               = ftmac100_get_link,
};

/******************************************************************************
 * interrupt handler
 *****************************************************************************/
static irqreturn_t ftmac100_interrupt(int irq, void *dev_id)
{
        struct net_device *netdev = dev_id;
        struct ftmac100 *priv = netdev_priv(netdev);

        if (likely(netif_running(netdev))) {
                /* Disable interrupts for polling */
                ftmac100_disable_all_int(priv);
                napi_schedule(&priv->napi);
        }

        return IRQ_HANDLED;
}

/******************************************************************************
 * struct napi_struct functions
 *****************************************************************************/
static int ftmac100_poll(struct napi_struct *napi, int budget)
{
        struct ftmac100 *priv = container_of(napi, struct ftmac100, napi);
        struct net_device *netdev = priv->netdev;
        unsigned int status;
        bool completed = true;
        int rx = 0;

        status = ioread32(priv->base + FTMAC100_OFFSET_ISR);

        if (status & (FTMAC100_INT_RPKT_FINISH | FTMAC100_INT_NORXBUF)) {
                /*
                 * FTMAC100_INT_RPKT_FINISH:
                 *      RX DMA has received packets into RX buffer successfully
                 *
                 * FTMAC100_INT_NORXBUF:
                 *      RX buffer unavailable
                 */
                bool retry;

                do {
                        retry = ftmac100_rx_packet(priv, &rx);
                } while (retry && rx < budget);

                if (retry && rx == budget)
                        completed = false;
        }

        if (status & (FTMAC100_INT_XPKT_OK | FTMAC100_INT_XPKT_LOST)) {
                /*
                 * FTMAC100_INT_XPKT_OK:
                 *      packet transmitted to ethernet successfully
                 *
                 * FTMAC100_INT_XPKT_LOST:
                 *      packet transmitted to ethernet lost due to late
                 *      collision or excessive collision
                 */
                ftmac100_tx_complete(priv);
        }

        if (status & (FTMAC100_INT_NORXBUF | FTMAC100_INT_RPKT_LOST |
                      FTMAC100_INT_AHB_ERR | FTMAC100_INT_PHYSTS_CHG)) {
                if (net_ratelimit())
                        netdev_info(netdev, "[ISR] = 0x%x: %s%s%s%s\n", status,
                                    status & FTMAC100_INT_NORXBUF ? "NORXBUF " : "",
                                    status & FTMAC100_INT_RPKT_LOST ? "RPKT_LOST " : "",
                                    status & FTMAC100_INT_AHB_ERR ? "AHB_ERR " : "",
                                    status & FTMAC100_INT_PHYSTS_CHG ? "PHYSTS_CHG" : "");

                if (status & FTMAC100_INT_NORXBUF) {
                        /* RX buffer unavailable */
                        netdev->stats.rx_over_errors++;
                }

                if (status & FTMAC100_INT_RPKT_LOST) {
                        /* received packet lost due to RX FIFO full */
                        netdev->stats.rx_fifo_errors++;
                }

                if (status & FTMAC100_INT_PHYSTS_CHG) {
                        /* PHY link status change */
                        mii_check_link(&priv->mii);
                }
        }

        if (completed) {
                /* stop polling */
                napi_complete(napi);
                ftmac100_enable_all_int(priv);
        }

        return rx;
}

/******************************************************************************
 * struct net_device_ops functions
 *****************************************************************************/
static int ftmac100_open(struct net_device *netdev)
{
        struct ftmac100 *priv = netdev_priv(netdev);
        int err;

        err = ftmac100_alloc_buffers(priv);
        if (err) {
                netdev_err(netdev, "failed to allocate buffers\n");
                goto err_alloc;
        }

        err = request_irq(priv->irq, ftmac100_interrupt, 0, netdev->name, netdev);
        if (err) {
                netdev_err(netdev, "failed to request irq %d\n", priv->irq);
                goto err_irq;
        }

        priv->rx_pointer = 0;
        priv->tx_clean_pointer = 0;
        priv->tx_pointer = 0;
        priv->tx_pending = 0;

        err = ftmac100_start_hw(priv);
        if (err)
                goto err_hw;

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

        ftmac100_enable_all_int(priv);

        return 0;

err_hw:
        free_irq(priv->irq, netdev);
err_irq:
        ftmac100_free_buffers(priv);
err_alloc:
        return err;
}

static int ftmac100_stop(struct net_device *netdev)
{
        struct ftmac100 *priv = netdev_priv(netdev);

        ftmac100_disable_all_int(priv);
        netif_stop_queue(netdev);
        napi_disable(&priv->napi);
        ftmac100_stop_hw(priv);
        free_irq(priv->irq, netdev);
        ftmac100_free_buffers(priv);

        return 0;
}

static int ftmac100_hard_start_xmit(struct sk_buff *skb, struct net_device *netdev)
{
        struct ftmac100 *priv = netdev_priv(netdev);
        dma_addr_t map;

        if (unlikely(skb->len > MAX_PKT_SIZE)) {
                if (net_ratelimit())
                        netdev_dbg(netdev, "tx packet too big\n");

                netdev->stats.tx_dropped++;
                dev_kfree_skb(skb);
                return NETDEV_TX_OK;
        }

        map = dma_map_single(priv->dev, skb->data, skb_headlen(skb), DMA_TO_DEVICE);
        if (unlikely(dma_mapping_error(priv->dev, map))) {
                /* drop packet */
                if (net_ratelimit())
                        netdev_err(netdev, "map socket buffer failed\n");

                netdev->stats.tx_dropped++;
                dev_kfree_skb(skb);
                return NETDEV_TX_OK;
        }

        return ftmac100_xmit(priv, skb, map);
}

/* optional */
static int ftmac100_do_ioctl(struct net_device *netdev, struct ifreq *ifr, int cmd)
{
        struct ftmac100 *priv = netdev_priv(netdev);
        struct mii_ioctl_data *data = if_mii(ifr);

        return generic_mii_ioctl(&priv->mii, data, cmd, NULL);
}

static const struct net_device_ops ftmac100_netdev_ops = {
        .ndo_open               = ftmac100_open,
        .ndo_stop               = ftmac100_stop,
        .ndo_start_xmit         = ftmac100_hard_start_xmit,
        .ndo_set_mac_address    = eth_mac_addr,
        .ndo_validate_addr      = eth_validate_addr,
        .ndo_do_ioctl           = ftmac100_do_ioctl,
};

/******************************************************************************
 * struct platform_driver functions
 *****************************************************************************/
static int ftmac100_probe(struct platform_device *pdev)
{
        struct resource *res;
        int irq;
        struct net_device *netdev;
        struct ftmac100 *priv;
        int err;

        if (!pdev)
                return -ENODEV;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return -ENXIO;

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

        /* setup net_device */
        netdev = alloc_etherdev(sizeof(*priv));
        if (!netdev) {
                err = -ENOMEM;
                goto err_alloc_etherdev;
        }

        SET_NETDEV_DEV(netdev, &pdev->dev);
        netdev->ethtool_ops = &ftmac100_ethtool_ops;
        netdev->netdev_ops = &ftmac100_netdev_ops;

        platform_set_drvdata(pdev, netdev);

        /* setup private data */
        priv = netdev_priv(netdev);
        priv->netdev = netdev;
        priv->dev = &pdev->dev;

        spin_lock_init(&priv->tx_lock);

        /* initialize NAPI */
        netif_napi_add(netdev, &priv->napi, ftmac100_poll, 64);

        /* map io memory */
        priv->res = request_mem_region(res->start, resource_size(res),
                                       dev_name(&pdev->dev));
        if (!priv->res) {
                dev_err(&pdev->dev, "Could not reserve memory region\n");
                err = -ENOMEM;
                goto err_req_mem;
        }

        priv->base = ioremap(res->start, resource_size(res));
        if (!priv->base) {
                dev_err(&pdev->dev, "Failed to ioremap ethernet registers\n");
                err = -EIO;
                goto err_ioremap;
        }

        priv->irq = irq;

        /* initialize struct mii_if_info */
        priv->mii.phy_id        = 0;
        priv->mii.phy_id_mask   = 0x1f;
        priv->mii.reg_num_mask  = 0x1f;
        priv->mii.dev           = netdev;
        priv->mii.mdio_read     = ftmac100_mdio_read;
        priv->mii.mdio_write    = ftmac100_mdio_write;

        /* register network device */
        err = register_netdev(netdev);
        if (err) {
                dev_err(&pdev->dev, "Failed to register netdev\n");
                goto err_register_netdev;
        }

        netdev_info(netdev, "irq %d, mapped at %p\n", priv->irq, priv->base);

        if (!is_valid_ether_addr(netdev->dev_addr)) {
                eth_hw_addr_random(netdev);
                netdev_info(netdev, "generated random MAC address %pM\n",
                            netdev->dev_addr);
        }

        return 0;

err_register_netdev:
        iounmap(priv->base);
err_ioremap:
        release_resource(priv->res);
err_req_mem:
        netif_napi_del(&priv->napi);
        free_netdev(netdev);
err_alloc_etherdev:
        return err;
}

static int __exit ftmac100_remove(struct platform_device *pdev)
{
        struct net_device *netdev;
        struct ftmac100 *priv;

        netdev = platform_get_drvdata(pdev);
        priv = netdev_priv(netdev);

        unregister_netdev(netdev);

        iounmap(priv->base);
        release_resource(priv->res);

        netif_napi_del(&priv->napi);
        free_netdev(netdev);
        return 0;
}

static struct platform_driver ftmac100_driver = {
        .probe          = ftmac100_probe,
        .remove         = __exit_p(ftmac100_remove),
        .driver         = {
                .name   = DRV_NAME,
        },
};

/******************************************************************************
 * initialization / finalization
 *****************************************************************************/
static int __init ftmac100_init(void)
{
        pr_info("Loading version " DRV_VERSION " ...\n");
        return platform_driver_register(&ftmac100_driver);
}

static void __exit ftmac100_exit(void)
{
        platform_driver_unregister(&ftmac100_driver);
}

module_init(ftmac100_init);
module_exit(ftmac100_exit);

MODULE_AUTHOR("Po-Yu Chuang <ratbert@faraday-tech.com>");
MODULE_DESCRIPTION("FTMAC100 driver");
MODULE_LICENSE("GPL");