Spidernet Remove unused variable

[linux-2.6-omap-h63xx.git] / drivers / net / spider_net.c

/*
 * Network device driver for Cell Processor-Based Blade
 *
 * (C) Copyright IBM Corp. 2005
 *
 * Authors : Utz Bacher <utz.bacher@de.ibm.com>
 *           Jens Osterkamp <Jens.Osterkamp@de.ibm.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, 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.
 */

#include <linux/compiler.h>
#include <linux/crc32.h>
#include <linux/delay.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/firmware.h>
#include <linux/if_vlan.h>
#include <linux/in.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/ip.h>
#include <linux/kernel.h>
#include <linux/mii.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/device.h>
#include <linux/pci.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/tcp.h>
#include <linux/types.h>
#include <linux/vmalloc.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
#include <asm/bitops.h>
#include <asm/pci-bridge.h>
#include <net/checksum.h>

#include "spider_net.h"

MODULE_AUTHOR("Utz Bacher <utz.bacher@de.ibm.com> and Jens Osterkamp " \
              "<Jens.Osterkamp@de.ibm.com>");
MODULE_DESCRIPTION("Spider Southbridge Gigabit Ethernet driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(VERSION);

static int rx_descriptors = SPIDER_NET_RX_DESCRIPTORS_DEFAULT;
static int tx_descriptors = SPIDER_NET_TX_DESCRIPTORS_DEFAULT;

module_param(rx_descriptors, int, 0444);
module_param(tx_descriptors, int, 0444);

MODULE_PARM_DESC(rx_descriptors, "number of descriptors used " \
                 "in rx chains");
MODULE_PARM_DESC(tx_descriptors, "number of descriptors used " \
                 "in tx chain");

char spider_net_driver_name[] = "spidernet";

static struct pci_device_id spider_net_pci_tbl[] = {
        { PCI_VENDOR_ID_TOSHIBA_2, PCI_DEVICE_ID_TOSHIBA_SPIDER_NET,
          PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0UL },
        { 0, }
};

MODULE_DEVICE_TABLE(pci, spider_net_pci_tbl);

/**
 * spider_net_read_reg - reads an SMMIO register of a card
 * @card: device structure
 * @reg: register to read from
 *
 * returns the content of the specified SMMIO register.
 */
static inline u32
spider_net_read_reg(struct spider_net_card *card, u32 reg)
{
        /* We use the powerpc specific variants instead of readl_be() because
         * we know spidernet is not a real PCI device and we can thus avoid the
         * performance hit caused by the PCI workarounds.
         */
        return in_be32(card->regs + reg);
}

/**
 * spider_net_write_reg - writes to an SMMIO register of a card
 * @card: device structure
 * @reg: register to write to
 * @value: value to write into the specified SMMIO register
 */
static inline void
spider_net_write_reg(struct spider_net_card *card, u32 reg, u32 value)
{
        /* We use the powerpc specific variants instead of writel_be() because
         * we know spidernet is not a real PCI device and we can thus avoid the
         * performance hit caused by the PCI workarounds.
         */
        out_be32(card->regs + reg, value);
}

/** spider_net_write_phy - write to phy register
 * @netdev: adapter to be written to
 * @mii_id: id of MII
 * @reg: PHY register
 * @val: value to be written to phy register
 *
 * spider_net_write_phy_register writes to an arbitrary PHY
 * register via the spider GPCWOPCMD register. We assume the queue does
 * not run full (not more than 15 commands outstanding).
 **/
static void
spider_net_write_phy(struct net_device *netdev, int mii_id,
                     int reg, int val)
{
        struct spider_net_card *card = netdev_priv(netdev);
        u32 writevalue;

        writevalue = ((u32)mii_id << 21) |
                ((u32)reg << 16) | ((u32)val);

        spider_net_write_reg(card, SPIDER_NET_GPCWOPCMD, writevalue);
}

/** spider_net_read_phy - read from phy register
 * @netdev: network device to be read from
 * @mii_id: id of MII
 * @reg: PHY register
 *
 * Returns value read from PHY register
 *
 * spider_net_write_phy reads from an arbitrary PHY
 * register via the spider GPCROPCMD register
 **/
static int
spider_net_read_phy(struct net_device *netdev, int mii_id, int reg)
{
        struct spider_net_card *card = netdev_priv(netdev);
        u32 readvalue;

        readvalue = ((u32)mii_id << 21) | ((u32)reg << 16);
        spider_net_write_reg(card, SPIDER_NET_GPCROPCMD, readvalue);

        /* we don't use semaphores to wait for an SPIDER_NET_GPROPCMPINT
         * interrupt, as we poll for the completion of the read operation
         * in spider_net_read_phy. Should take about 50 us */
        do {
                readvalue = spider_net_read_reg(card, SPIDER_NET_GPCROPCMD);
        } while (readvalue & SPIDER_NET_GPREXEC);

        readvalue &= SPIDER_NET_GPRDAT_MASK;

        return readvalue;
}

/**
 * spider_net_rx_irq_off - switch off rx irq on this spider card
 * @card: device structure
 *
 * switches off rx irq by masking them out in the GHIINTnMSK register
 */
static void
spider_net_rx_irq_off(struct spider_net_card *card)
{
        u32 regvalue;

        regvalue = SPIDER_NET_INT0_MASK_VALUE & (~SPIDER_NET_RXINT);
        spider_net_write_reg(card, SPIDER_NET_GHIINT0MSK, regvalue);
}

/**
 * spider_net_rx_irq_on - switch on rx irq on this spider card
 * @card: device structure
 *
 * switches on rx irq by enabling them in the GHIINTnMSK register
 */
static void
spider_net_rx_irq_on(struct spider_net_card *card)
{
        u32 regvalue;

        regvalue = SPIDER_NET_INT0_MASK_VALUE | SPIDER_NET_RXINT;
        spider_net_write_reg(card, SPIDER_NET_GHIINT0MSK, regvalue);
}

/**
 * spider_net_set_promisc - sets the unicast address or the promiscuous mode
 * @card: card structure
 *
 * spider_net_set_promisc sets the unicast destination address filter and
 * thus either allows for non-promisc mode or promisc mode
 */
static void
spider_net_set_promisc(struct spider_net_card *card)
{
        u32 macu, macl;
        struct net_device *netdev = card->netdev;

        if (netdev->flags & IFF_PROMISC) {
                /* clear destination entry 0 */
                spider_net_write_reg(card, SPIDER_NET_GMRUAFILnR, 0);
                spider_net_write_reg(card, SPIDER_NET_GMRUAFILnR + 0x04, 0);
                spider_net_write_reg(card, SPIDER_NET_GMRUA0FIL15R,
                                     SPIDER_NET_PROMISC_VALUE);
        } else {
                macu = netdev->dev_addr[0];
                macu <<= 8;
                macu |= netdev->dev_addr[1];
                memcpy(&macl, &netdev->dev_addr[2], sizeof(macl));

                macu |= SPIDER_NET_UA_DESCR_VALUE;
                spider_net_write_reg(card, SPIDER_NET_GMRUAFILnR, macu);
                spider_net_write_reg(card, SPIDER_NET_GMRUAFILnR + 0x04, macl);
                spider_net_write_reg(card, SPIDER_NET_GMRUA0FIL15R,
                                     SPIDER_NET_NONPROMISC_VALUE);
        }
}

/**
 * spider_net_get_mac_address - read mac address from spider card
 * @card: device structure
 *
 * reads MAC address from GMACUNIMACU and GMACUNIMACL registers
 */
static int
spider_net_get_mac_address(struct net_device *netdev)
{
        struct spider_net_card *card = netdev_priv(netdev);
        u32 macl, macu;

        macl = spider_net_read_reg(card, SPIDER_NET_GMACUNIMACL);
        macu = spider_net_read_reg(card, SPIDER_NET_GMACUNIMACU);

        netdev->dev_addr[0] = (macu >> 24) & 0xff;
        netdev->dev_addr[1] = (macu >> 16) & 0xff;
        netdev->dev_addr[2] = (macu >> 8) & 0xff;
        netdev->dev_addr[3] = macu & 0xff;
        netdev->dev_addr[4] = (macl >> 8) & 0xff;
        netdev->dev_addr[5] = macl & 0xff;

        if (!is_valid_ether_addr(&netdev->dev_addr[0]))
                return -EINVAL;

        return 0;
}

/**
 * spider_net_get_descr_status -- returns the status of a descriptor
 * @descr: descriptor to look at
 *
 * returns the status as in the dmac_cmd_status field of the descriptor
 */
static inline int
spider_net_get_descr_status(struct spider_net_descr *descr)
{
        return descr->dmac_cmd_status & SPIDER_NET_DESCR_IND_PROC_MASK;
}

/**
 * spider_net_free_chain - free descriptor chain
 * @card: card structure
 * @chain: address of chain
 *
 */
static void
spider_net_free_chain(struct spider_net_card *card,
                      struct spider_net_descr_chain *chain)
{
        struct spider_net_descr *descr;

        descr = chain->ring;
        do {
                descr->bus_addr = 0;
                descr->next_descr_addr = 0;
                descr = descr->next;
        } while (descr != chain->ring);

        dma_free_coherent(&card->pdev->dev, chain->num_desc,
            chain->ring, chain->dma_addr);
}

/**
 * spider_net_init_chain - alloc and link descriptor chain
 * @card: card structure
 * @chain: address of chain
 *
 * We manage a circular list that mirrors the hardware structure,
 * except that the hardware uses bus addresses.
 *
 * Returns 0 on success, <0 on failure
 */
static int
spider_net_init_chain(struct spider_net_card *card,
                       struct spider_net_descr_chain *chain)
{
        int i;
        struct spider_net_descr *descr;
        dma_addr_t buf;
        size_t alloc_size;

        alloc_size = chain->num_desc * sizeof (struct spider_net_descr);

        chain->ring = dma_alloc_coherent(&card->pdev->dev, alloc_size,
                &chain->dma_addr, GFP_KERNEL);

        if (!chain->ring)
                return -ENOMEM;

        descr = chain->ring;
        memset(descr, 0, alloc_size);

        /* Set up the hardware pointers in each descriptor */
        buf = chain->dma_addr;
        for (i=0; i < chain->num_desc; i++, descr++) {
                descr->dmac_cmd_status = SPIDER_NET_DESCR_NOT_IN_USE;

                descr->bus_addr = buf;
                descr->next_descr_addr = 0;
                descr->next = descr + 1;
                descr->prev = descr - 1;

                buf += sizeof(struct spider_net_descr);
        }
        /* do actual circular list */
        (descr-1)->next = chain->ring;
        chain->ring->prev = descr-1;

        spin_lock_init(&chain->lock);
        chain->head = chain->ring;
        chain->tail = chain->ring;
        return 0;
}

/**
 * spider_net_free_rx_chain_contents - frees descr contents in rx chain
 * @card: card structure
 *
 * returns 0 on success, <0 on failure
 */
static void
spider_net_free_rx_chain_contents(struct spider_net_card *card)
{
        struct spider_net_descr *descr;

        descr = card->rx_chain.head;
        do {
                if (descr->skb) {
                        dev_kfree_skb(descr->skb);
                        pci_unmap_single(card->pdev, descr->buf_addr,
                                         SPIDER_NET_MAX_FRAME,
                                         PCI_DMA_BIDIRECTIONAL);
                }
                descr = descr->next;
        } while (descr != card->rx_chain.head);
}

/**
 * spider_net_prepare_rx_descr - Reinitialize RX descriptor
 * @card: card structure
 * @descr: descriptor to re-init
 *
 * Return 0 on succes, <0 on failure.
 *
 * Allocates a new rx skb, iommu-maps it and attaches it to the
 * descriptor. Mark the descriptor as activated, ready-to-use.
 */
static int
spider_net_prepare_rx_descr(struct spider_net_card *card,
                            struct spider_net_descr *descr)
{
        dma_addr_t buf;
        int offset;
        int bufsize;

        /* we need to round up the buffer size to a multiple of 128 */
        bufsize = (SPIDER_NET_MAX_FRAME + SPIDER_NET_RXBUF_ALIGN - 1) &
                (~(SPIDER_NET_RXBUF_ALIGN - 1));

        /* and we need to have it 128 byte aligned, therefore we allocate a
         * bit more */
        /* allocate an skb */
        descr->skb = dev_alloc_skb(bufsize + SPIDER_NET_RXBUF_ALIGN - 1);
        if (!descr->skb) {
                if (netif_msg_rx_err(card) && net_ratelimit())
                        pr_err("Not enough memory to allocate rx buffer\n");
                card->spider_stats.alloc_rx_skb_error++;
                return -ENOMEM;
        }
        descr->buf_size = bufsize;
        descr->result_size = 0;
        descr->valid_size = 0;
        descr->data_status = 0;
        descr->data_error = 0;

        offset = ((unsigned long)descr->skb->data) &
                (SPIDER_NET_RXBUF_ALIGN - 1);
        if (offset)
                skb_reserve(descr->skb, SPIDER_NET_RXBUF_ALIGN - offset);
        /* iommu-map the skb */
        buf = pci_map_single(card->pdev, descr->skb->data,
                        SPIDER_NET_MAX_FRAME, PCI_DMA_FROMDEVICE);
        descr->buf_addr = buf;
        if (pci_dma_mapping_error(buf)) {
                dev_kfree_skb_any(descr->skb);
                if (netif_msg_rx_err(card) && net_ratelimit())
                        pr_err("Could not iommu-map rx buffer\n");
                card->spider_stats.rx_iommu_map_error++;
                descr->dmac_cmd_status = SPIDER_NET_DESCR_NOT_IN_USE;
        } else {
                descr->dmac_cmd_status = SPIDER_NET_DESCR_CARDOWNED |
                                         SPIDER_NET_DMAC_NOINTR_COMPLETE;
        }

        return 0;
}

/**
 * spider_net_enable_rxchtails - sets RX dmac chain tail addresses
 * @card: card structure
 *
 * spider_net_enable_rxchtails sets the RX DMAC chain tail adresses in the
 * chip by writing to the appropriate register. DMA is enabled in
 * spider_net_enable_rxdmac.
 */
static inline void
spider_net_enable_rxchtails(struct spider_net_card *card)
{
        /* assume chain is aligned correctly */
        spider_net_write_reg(card, SPIDER_NET_GDADCHA ,
                             card->rx_chain.tail->bus_addr);
}

/**
 * spider_net_enable_rxdmac - enables a receive DMA controller
 * @card: card structure
 *
 * spider_net_enable_rxdmac enables the DMA controller by setting RX_DMA_EN
 * in the GDADMACCNTR register
 */
static inline void
spider_net_enable_rxdmac(struct spider_net_card *card)
{
        wmb();
        spider_net_write_reg(card, SPIDER_NET_GDADMACCNTR,
                             SPIDER_NET_DMA_RX_VALUE);
}

/**
 * spider_net_refill_rx_chain - refills descriptors/skbs in the rx chains
 * @card: card structure
 *
 * refills descriptors in the rx chain: allocates skbs and iommu-maps them.
 */
static void
spider_net_refill_rx_chain(struct spider_net_card *card)
{
        struct spider_net_descr_chain *chain = &card->rx_chain;
        unsigned long flags;

        /* one context doing the refill (and a second context seeing that
         * and omitting it) is ok. If called by NAPI, we'll be called again
         * as spider_net_decode_one_descr is called several times. If some
         * interrupt calls us, the NAPI is about to clean up anyway. */
        if (!spin_trylock_irqsave(&chain->lock, flags))
                return;

        while (spider_net_get_descr_status(chain->head) ==
                        SPIDER_NET_DESCR_NOT_IN_USE) {
                if (spider_net_prepare_rx_descr(card, chain->head))
                        break;
                chain->head = chain->head->next;
        }

        spin_unlock_irqrestore(&chain->lock, flags);
}

/**
 * spider_net_alloc_rx_skbs - allocates rx skbs in rx descriptor chains
 * @card: card structure
 *
 * returns 0 on success, <0 on failure
 */
static int
spider_net_alloc_rx_skbs(struct spider_net_card *card)
{
        int result;
        struct spider_net_descr_chain *chain;

        result = -ENOMEM;

        chain = &card->rx_chain;
        /* put at least one buffer into the chain. if this fails,
         * we've got a problem. if not, spider_net_refill_rx_chain
         * will do the rest at the end of this function */
        if (spider_net_prepare_rx_descr(card, chain->head))
                goto error;
        else
                chain->head = chain->head->next;

        /* this will allocate the rest of the rx buffers; if not, it's
         * business as usual later on */
        spider_net_refill_rx_chain(card);
        spider_net_enable_rxdmac(card);
        return 0;

error:
        spider_net_free_rx_chain_contents(card);
        return result;
}

/**
 * spider_net_get_multicast_hash - generates hash for multicast filter table
 * @addr: multicast address
 *
 * returns the hash value.
 *
 * spider_net_get_multicast_hash calculates a hash value for a given multicast
 * address, that is used to set the multicast filter tables
 */
static u8
spider_net_get_multicast_hash(struct net_device *netdev, __u8 *addr)
{
        u32 crc;
        u8 hash;
        char addr_for_crc[ETH_ALEN] = { 0, };
        int i, bit;

        for (i = 0; i < ETH_ALEN * 8; i++) {
                bit = (addr[i / 8] >> (i % 8)) & 1;
                addr_for_crc[ETH_ALEN - 1 - i / 8] += bit << (7 - (i % 8));
        }

        crc = crc32_be(~0, addr_for_crc, netdev->addr_len);

        hash = (crc >> 27);
        hash <<= 3;
        hash |= crc & 7;
        hash &= 0xff;

        return hash;
}

/**
 * spider_net_set_multi - sets multicast addresses and promisc flags
 * @netdev: interface device structure
 *
 * spider_net_set_multi configures multicast addresses as needed for the
 * netdev interface. It also sets up multicast, allmulti and promisc
 * flags appropriately
 */
static void
spider_net_set_multi(struct net_device *netdev)
{
        struct dev_mc_list *mc;
        u8 hash;
        int i;
        u32 reg;
        struct spider_net_card *card = netdev_priv(netdev);
        unsigned long bitmask[SPIDER_NET_MULTICAST_HASHES / BITS_PER_LONG] =
                {0, };

        spider_net_set_promisc(card);

        if (netdev->flags & IFF_ALLMULTI) {
                for (i = 0; i < SPIDER_NET_MULTICAST_HASHES; i++) {
                        set_bit(i, bitmask);
                }
                goto write_hash;
        }

        /* well, we know, what the broadcast hash value is: it's xfd
        hash = spider_net_get_multicast_hash(netdev, netdev->broadcast); */
        set_bit(0xfd, bitmask);

        for (mc = netdev->mc_list; mc; mc = mc->next) {
                hash = spider_net_get_multicast_hash(netdev, mc->dmi_addr);
                set_bit(hash, bitmask);
        }

write_hash:
        for (i = 0; i < SPIDER_NET_MULTICAST_HASHES / 4; i++) {
                reg = 0;
                if (test_bit(i * 4, bitmask))
                        reg += 0x08;
                reg <<= 8;
                if (test_bit(i * 4 + 1, bitmask))
                        reg += 0x08;
                reg <<= 8;
                if (test_bit(i * 4 + 2, bitmask))
                        reg += 0x08;
                reg <<= 8;
                if (test_bit(i * 4 + 3, bitmask))
                        reg += 0x08;

                spider_net_write_reg(card, SPIDER_NET_GMRMHFILnR + i * 4, reg);
        }
}

/**
 * spider_net_disable_rxdmac - disables the receive DMA controller
 * @card: card structure
 *
 * spider_net_disable_rxdmac terminates processing on the DMA controller by
 * turing off DMA and issueing a force end
 */
static void
spider_net_disable_rxdmac(struct spider_net_card *card)
{
        spider_net_write_reg(card, SPIDER_NET_GDADMACCNTR,
                             SPIDER_NET_DMA_RX_FEND_VALUE);
}

/**
 * spider_net_prepare_tx_descr - fill tx descriptor with skb data
 * @card: card structure
 * @descr: descriptor structure to fill out
 * @skb: packet to use
 *
 * returns 0 on success, <0 on failure.
 *
 * fills out the descriptor structure with skb data and len. Copies data,
 * if needed (32bit DMA!)
 */
static int
spider_net_prepare_tx_descr(struct spider_net_card *card,
                            struct sk_buff *skb)
{
        struct spider_net_descr *descr;
        dma_addr_t buf;
        unsigned long flags;

        buf = pci_map_single(card->pdev, skb->data, skb->len, PCI_DMA_TODEVICE);
        if (pci_dma_mapping_error(buf)) {
                if (netif_msg_tx_err(card) && net_ratelimit())
                        pr_err("could not iommu-map packet (%p, %i). "
                                  "Dropping packet\n", skb->data, skb->len);
                card->spider_stats.tx_iommu_map_error++;
                return -ENOMEM;
        }

        spin_lock_irqsave(&card->tx_chain.lock, flags);
        descr = card->tx_chain.head;
        card->tx_chain.head = descr->next;

        descr->buf_addr = buf;
        descr->buf_size = skb->len;
        descr->next_descr_addr = 0;
        descr->skb = skb;
        descr->data_status = 0;

        descr->dmac_cmd_status =
                        SPIDER_NET_DESCR_CARDOWNED | SPIDER_NET_DMAC_NOCS;
        spin_unlock_irqrestore(&card->tx_chain.lock, flags);

        if (skb->protocol == htons(ETH_P_IP))
                switch (skb->nh.iph->protocol) {
                case IPPROTO_TCP:
                        descr->dmac_cmd_status |= SPIDER_NET_DMAC_TCP;
                        break;
                case IPPROTO_UDP:
                        descr->dmac_cmd_status |= SPIDER_NET_DMAC_UDP;
                        break;
                }

        /* Chain the bus address, so that the DMA engine finds this descr. */
        descr->prev->next_descr_addr = descr->bus_addr;

        card->netdev->trans_start = jiffies; /* set netdev watchdog timer */
        return 0;
}

static int
spider_net_set_low_watermark(struct spider_net_card *card)
{
        unsigned long flags;
        int status;
        int cnt=0;
        int i;
        struct spider_net_descr *descr = card->tx_chain.tail;

        /* Measure the length of the queue. Measurement does not
         * need to be precise -- does not need a lock. */
        while (descr != card->tx_chain.head) {
                status = descr->dmac_cmd_status & SPIDER_NET_DESCR_NOT_IN_USE;
                if (status == SPIDER_NET_DESCR_NOT_IN_USE)
                        break;
                descr = descr->next;
                cnt++;
        }

        /* If TX queue is short, don't even bother with interrupts */
        if (cnt < card->tx_chain.num_desc/4)
                return cnt;

        /* Set low-watermark 3/4th's of the way into the queue. */
        descr = card->tx_chain.tail;
        cnt = (cnt*3)/4;
        for (i=0;i<cnt; i++)
                descr = descr->next;

        /* Set the new watermark, clear the old watermark */
        spin_lock_irqsave(&card->tx_chain.lock, flags);
        descr->dmac_cmd_status |= SPIDER_NET_DESCR_TXDESFLG;
        if (card->low_watermark && card->low_watermark != descr)
                card->low_watermark->dmac_cmd_status =
                     card->low_watermark->dmac_cmd_status & ~SPIDER_NET_DESCR_TXDESFLG;
        card->low_watermark = descr;
        spin_unlock_irqrestore(&card->tx_chain.lock, flags);
        return cnt;
}

/**
 * spider_net_release_tx_chain - processes sent tx descriptors
 * @card: adapter structure
 * @brutal: if set, don't care about whether descriptor seems to be in use
 *
 * returns 0 if the tx ring is empty, otherwise 1.
 *
 * spider_net_release_tx_chain releases the tx descriptors that spider has
 * finished with (if non-brutal) or simply release tx descriptors (if brutal).
 * If some other context is calling this function, we return 1 so that we're
 * scheduled again (if we were scheduled) and will not loose initiative.
 */
static int
spider_net_release_tx_chain(struct spider_net_card *card, int brutal)
{
        struct spider_net_descr_chain *chain = &card->tx_chain;
        struct spider_net_descr *descr;
        struct sk_buff *skb;
        u32 buf_addr;
        unsigned long flags;
        int status;

        while (chain->tail != chain->head) {
                spin_lock_irqsave(&chain->lock, flags);
                descr = chain->tail;

                status = spider_net_get_descr_status(descr);
                switch (status) {
                case SPIDER_NET_DESCR_COMPLETE:
                        card->netdev_stats.tx_packets++;
                        card->netdev_stats.tx_bytes += descr->skb->len;
                        break;

                case SPIDER_NET_DESCR_CARDOWNED:
                        if (!brutal) {
                                spin_unlock_irqrestore(&chain->lock, flags);
                                return 1;
                        }

                        /* fallthrough, if we release the descriptors
                         * brutally (then we don't care about
                         * SPIDER_NET_DESCR_CARDOWNED) */

                case SPIDER_NET_DESCR_RESPONSE_ERROR:
                case SPIDER_NET_DESCR_PROTECTION_ERROR:
                case SPIDER_NET_DESCR_FORCE_END:
                        if (netif_msg_tx_err(card))
                                pr_err("%s: forcing end of tx descriptor "
                                       "with status x%02x\n",
                                       card->netdev->name, status);
                        card->netdev_stats.tx_errors++;
                        break;

                default:
                        card->netdev_stats.tx_dropped++;
                        if (!brutal) {
                                spin_unlock_irqrestore(&chain->lock, flags);
                                return 1;
                        }
                }

                chain->tail = descr->next;
                descr->dmac_cmd_status |= SPIDER_NET_DESCR_NOT_IN_USE;
                skb = descr->skb;
                buf_addr = descr->buf_addr;
                spin_unlock_irqrestore(&chain->lock, flags);

                /* unmap the skb */
                if (skb) {
                        pci_unmap_single(card->pdev, buf_addr, skb->len,
                                        PCI_DMA_TODEVICE);
                        dev_kfree_skb(skb);
                }
        }
        return 0;
}

/**
 * spider_net_kick_tx_dma - enables TX DMA processing
 * @card: card structure
 * @descr: descriptor address to enable TX processing at
 *
 * This routine will start the transmit DMA running if
 * it is not already running. This routine ned only be
 * called when queueing a new packet to an empty tx queue.
 * Writes the current tx chain head as start address
 * of the tx descriptor chain and enables the transmission
 * DMA engine.
 */
static inline void
spider_net_kick_tx_dma(struct spider_net_card *card)
{
        struct spider_net_descr *descr;

        if (spider_net_read_reg(card, SPIDER_NET_GDTDMACCNTR) &
                        SPIDER_NET_TX_DMA_EN)
                goto out;

        descr = card->tx_chain.tail;
        for (;;) {
                if (spider_net_get_descr_status(descr) ==
                                SPIDER_NET_DESCR_CARDOWNED) {
                        spider_net_write_reg(card, SPIDER_NET_GDTDCHA,
                                        descr->bus_addr);
                        spider_net_write_reg(card, SPIDER_NET_GDTDMACCNTR,
                                        SPIDER_NET_DMA_TX_VALUE);
                        break;
                }
                if (descr == card->tx_chain.head)
                        break;
                descr = descr->next;
        }

out:
        mod_timer(&card->tx_timer, jiffies + SPIDER_NET_TX_TIMER);
}

/**
 * spider_net_xmit - transmits a frame over the device
 * @skb: packet to send out
 * @netdev: interface device structure
 *
 * returns 0 on success, !0 on failure
 */
static int
spider_net_xmit(struct sk_buff *skb, struct net_device *netdev)
{
        int cnt;
        struct spider_net_card *card = netdev_priv(netdev);
        struct spider_net_descr_chain *chain = &card->tx_chain;

        spider_net_release_tx_chain(card, 0);

        if ((chain->head->next == chain->tail->prev) ||
           (spider_net_prepare_tx_descr(card, skb) != 0)) {

                card->netdev_stats.tx_dropped++;
                netif_stop_queue(netdev);
                return NETDEV_TX_BUSY;
        }

        cnt = spider_net_set_low_watermark(card);
        if (cnt < 5)
                spider_net_kick_tx_dma(card);
        return NETDEV_TX_OK;
}

/**
 * spider_net_cleanup_tx_ring - cleans up the TX ring
 * @card: card structure
 *
 * spider_net_cleanup_tx_ring is called by either the tx_timer
 * or from the NAPI polling routine.
 * This routine releases resources associted with transmitted
 * packets, including updating the queue tail pointer.
 */
static void
spider_net_cleanup_tx_ring(struct spider_net_card *card)
{
        if ((spider_net_release_tx_chain(card, 0) != 0) &&
            (card->netdev->flags & IFF_UP)) {
                spider_net_kick_tx_dma(card);
                netif_wake_queue(card->netdev);
        }
}

/**
 * spider_net_do_ioctl - called for device ioctls
 * @netdev: interface device structure
 * @ifr: request parameter structure for ioctl
 * @cmd: command code for ioctl
 *
 * returns 0 on success, <0 on failure. Currently, we have no special ioctls.
 * -EOPNOTSUPP is returned, if an unknown ioctl was requested
 */
static int
spider_net_do_ioctl(struct net_device *netdev, struct ifreq *ifr, int cmd)
{
        switch (cmd) {
        default:
                return -EOPNOTSUPP;
        }
}

/**
 * spider_net_pass_skb_up - takes an skb from a descriptor and passes it on
 * @descr: descriptor to process
 * @card: card structure
 *
 * Fills out skb structure and passes the data to the stack.
 * The descriptor state is not changed.
 */
static void
spider_net_pass_skb_up(struct spider_net_descr *descr,
                       struct spider_net_card *card)
{
        struct sk_buff *skb;
        struct net_device *netdev;
        u32 data_status, data_error;

        data_status = descr->data_status;
        data_error = descr->data_error;
        netdev = card->netdev;

        skb = descr->skb;
        skb->dev = netdev;
        skb_put(skb, descr->valid_size);

        /* the card seems to add 2 bytes of junk in front
         * of the ethernet frame */
#define SPIDER_MISALIGN         2
        skb_pull(skb, SPIDER_MISALIGN);
        skb->protocol = eth_type_trans(skb, netdev);

        /* checksum offload */
        if (card->options.rx_csum) {
                if ( ( (data_status & SPIDER_NET_DATA_STATUS_CKSUM_MASK) ==
                       SPIDER_NET_DATA_STATUS_CKSUM_MASK) &&
                     !(data_error & SPIDER_NET_DATA_ERR_CKSUM_MASK))
                        skb->ip_summed = CHECKSUM_UNNECESSARY;
                else
                        skb->ip_summed = CHECKSUM_NONE;
        } else
                skb->ip_summed = CHECKSUM_NONE;

        if (data_status & SPIDER_NET_VLAN_PACKET) {
                /* further enhancements: HW-accel VLAN
                 * vlan_hwaccel_receive_skb
                 */
        }

        /* pass skb up to stack */
        netif_receive_skb(skb);

        /* update netdevice statistics */
        card->netdev_stats.rx_packets++;
        card->netdev_stats.rx_bytes += skb->len;
}

/**
 * spider_net_decode_one_descr - processes an rx descriptor
 * @card: card structure
 *
 * Returns 1 if a packet has been sent to the stack, otherwise 0
 *
 * Processes an rx descriptor by iommu-unmapping the data buffer and passing
 * the packet up to the stack. This function is called in softirq
 * context, e.g. either bottom half from interrupt or NAPI polling context
 */
static int
spider_net_decode_one_descr(struct spider_net_card *card)
{
        struct spider_net_descr_chain *chain = &card->rx_chain;
        struct spider_net_descr *descr = chain->tail;
        int status;

        status = spider_net_get_descr_status(descr);

        /* Nothing in the descriptor, or ring must be empty */
        if ((status == SPIDER_NET_DESCR_CARDOWNED) ||
            (status == SPIDER_NET_DESCR_NOT_IN_USE))
                return 0;

        /* descriptor definitively used -- move on tail */
        chain->tail = descr->next;

        /* unmap descriptor */
        pci_unmap_single(card->pdev, descr->buf_addr,
                        SPIDER_NET_MAX_FRAME, PCI_DMA_FROMDEVICE);

        if ( (status == SPIDER_NET_DESCR_RESPONSE_ERROR) ||
             (status == SPIDER_NET_DESCR_PROTECTION_ERROR) ||
             (status == SPIDER_NET_DESCR_FORCE_END) ) {
                if (netif_msg_rx_err(card))
                        pr_err("%s: dropping RX descriptor with state %d\n",
                               card->netdev->name, status);
                card->netdev_stats.rx_dropped++;
                goto bad_desc;
        }

        if ( (status != SPIDER_NET_DESCR_COMPLETE) &&
             (status != SPIDER_NET_DESCR_FRAME_END) ) {
                if (netif_msg_rx_err(card))
                        pr_err("%s: RX descriptor with unkown state %d\n",
                               card->netdev->name, status);
                card->spider_stats.rx_desc_unk_state++;
                goto bad_desc;
        }

        /* The cases we'll throw away the packet immediately */
        if (descr->data_error & SPIDER_NET_DESTROY_RX_FLAGS) {
                if (netif_msg_rx_err(card))
                        pr_err("%s: error in received descriptor found, "
                               "data_status=x%08x, data_error=x%08x\n",
                               card->netdev->name,
                               descr->data_status, descr->data_error);
                goto bad_desc;
        }

        /* Ok, we've got a packet in descr */
        spider_net_pass_skb_up(descr, card);
        descr->dmac_cmd_status = SPIDER_NET_DESCR_NOT_IN_USE;
        return 1;

bad_desc:
        dev_kfree_skb_irq(descr->skb);
        descr->dmac_cmd_status = SPIDER_NET_DESCR_NOT_IN_USE;
        return 0;
}

/**
 * spider_net_poll - NAPI poll function called by the stack to return packets
 * @netdev: interface device structure
 * @budget: number of packets we can pass to the stack at most
 *
 * returns 0 if no more packets available to the driver/stack. Returns 1,
 * if the quota is exceeded, but the driver has still packets.
 *
 * spider_net_poll returns all packets from the rx descriptors to the stack
 * (using netif_receive_skb). If all/enough packets are up, the driver
 * reenables interrupts and returns 0. If not, 1 is returned.
 */
static int
spider_net_poll(struct net_device *netdev, int *budget)
{
        struct spider_net_card *card = netdev_priv(netdev);
        int packets_to_do, packets_done = 0;
        int no_more_packets = 0;

        spider_net_cleanup_tx_ring(card);
        packets_to_do = min(*budget, netdev->quota);

        while (packets_to_do) {
                if (spider_net_decode_one_descr(card)) {
                        packets_done++;
                        packets_to_do--;
                } else {
                        /* no more packets for the stack */
                        no_more_packets = 1;
                        break;
                }
        }

        netdev->quota -= packets_done;
        *budget -= packets_done;
        spider_net_refill_rx_chain(card);
        spider_net_enable_rxdmac(card);

        /* if all packets are in the stack, enable interrupts and return 0 */
        /* if not, return 1 */
        if (no_more_packets) {
                netif_rx_complete(netdev);
                spider_net_rx_irq_on(card);
                return 0;
        }

        return 1;
}

/**
 * spider_net_vlan_rx_reg - initializes VLAN structures in the driver and card
 * @netdev: interface device structure
 * @grp: vlan_group structure that is registered (NULL on destroying interface)
 */
static void
spider_net_vlan_rx_reg(struct net_device *netdev, struct vlan_group *grp)
{
        /* further enhancement... yet to do */
        return;
}

/**
 * spider_net_vlan_rx_add - adds VLAN id to the card filter
 * @netdev: interface device structure
 * @vid: VLAN id to add
 */
static void
spider_net_vlan_rx_add(struct net_device *netdev, uint16_t vid)
{
        /* further enhancement... yet to do */
        /* add vid to card's VLAN filter table */
        return;
}

/**
 * spider_net_vlan_rx_kill - removes VLAN id to the card filter
 * @netdev: interface device structure
 * @vid: VLAN id to remove
 */
static void
spider_net_vlan_rx_kill(struct net_device *netdev, uint16_t vid)
{
        /* further enhancement... yet to do */
        /* remove vid from card's VLAN filter table */
}

/**
 * spider_net_get_stats - get interface statistics
 * @netdev: interface device structure
 *
 * returns the interface statistics residing in the spider_net_card struct
 */
static struct net_device_stats *
spider_net_get_stats(struct net_device *netdev)
{
        struct spider_net_card *card = netdev_priv(netdev);
        struct net_device_stats *stats = &card->netdev_stats;
        return stats;
}

/**
 * spider_net_change_mtu - changes the MTU of an interface
 * @netdev: interface device structure
 * @new_mtu: new MTU value
 *
 * returns 0 on success, <0 on failure
 */
static int
spider_net_change_mtu(struct net_device *netdev, int new_mtu)
{
        /* no need to re-alloc skbs or so -- the max mtu is about 2.3k
         * and mtu is outbound only anyway */
        if ( (new_mtu < SPIDER_NET_MIN_MTU ) ||
                (new_mtu > SPIDER_NET_MAX_MTU) )
                return -EINVAL;
        netdev->mtu = new_mtu;
        return 0;
}

/**
 * spider_net_set_mac - sets the MAC of an interface
 * @netdev: interface device structure
 * @ptr: pointer to new MAC address
 *
 * Returns 0 on success, <0 on failure. Currently, we don't support this
 * and will always return EOPNOTSUPP.
 */
static int
spider_net_set_mac(struct net_device *netdev, void *p)
{
        struct spider_net_card *card = netdev_priv(netdev);
        u32 macl, macu, regvalue;
        struct sockaddr *addr = p;

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

        /* switch off GMACTPE and GMACRPE */
        regvalue = spider_net_read_reg(card, SPIDER_NET_GMACOPEMD);
        regvalue &= ~((1 << 5) | (1 << 6));
        spider_net_write_reg(card, SPIDER_NET_GMACOPEMD, regvalue);

        /* write mac */
        macu = (addr->sa_data[0]<<24) + (addr->sa_data[1]<<16) +
                (addr->sa_data[2]<<8) + (addr->sa_data[3]);
        macl = (addr->sa_data[4]<<8) + (addr->sa_data[5]);
        spider_net_write_reg(card, SPIDER_NET_GMACUNIMACU, macu);
        spider_net_write_reg(card, SPIDER_NET_GMACUNIMACL, macl);

        /* switch GMACTPE and GMACRPE back on */
        regvalue = spider_net_read_reg(card, SPIDER_NET_GMACOPEMD);
        regvalue |= ((1 << 5) | (1 << 6));
        spider_net_write_reg(card, SPIDER_NET_GMACOPEMD, regvalue);

        spider_net_set_promisc(card);

        /* look up, whether we have been successful */
        if (spider_net_get_mac_address(netdev))
                return -EADDRNOTAVAIL;
        if (memcmp(netdev->dev_addr,addr->sa_data,netdev->addr_len))
                return -EADDRNOTAVAIL;

        return 0;
}

/**
 * spider_net_handle_error_irq - handles errors raised by an interrupt
 * @card: card structure
 * @status_reg: interrupt status register 0 (GHIINT0STS)
 *
 * spider_net_handle_error_irq treats or ignores all error conditions
 * found when an interrupt is presented
 */
static void
spider_net_handle_error_irq(struct spider_net_card *card, u32 status_reg)
{
        u32 error_reg1, error_reg2;
        u32 i;
        int show_error = 1;

        error_reg1 = spider_net_read_reg(card, SPIDER_NET_GHIINT1STS);
        error_reg2 = spider_net_read_reg(card, SPIDER_NET_GHIINT2STS);

        /* check GHIINT0STS ************************************/
        if (status_reg)
                for (i = 0; i < 32; i++)
                        if (status_reg & (1<<i))
                                switch (i)
        {
        /* let error_reg1 and error_reg2 evaluation decide, what to do
        case SPIDER_NET_PHYINT:
        case SPIDER_NET_GMAC2INT:
        case SPIDER_NET_GMAC1INT:
        case SPIDER_NET_GFIFOINT:
        case SPIDER_NET_DMACINT:
        case SPIDER_NET_GSYSINT:
                break; */

        case SPIDER_NET_GIPSINT:
                show_error = 0;
                break;

        case SPIDER_NET_GPWOPCMPINT:
                /* PHY write operation completed */
                show_error = 0;
                break;
        case SPIDER_NET_GPROPCMPINT:
                /* PHY read operation completed */
                /* we don't use semaphores, as we poll for the completion
                 * of the read operation in spider_net_read_phy. Should take
                 * about 50 us */
                show_error = 0;
                break;
        case SPIDER_NET_GPWFFINT:
                /* PHY command queue full */
                if (netif_msg_intr(card))
                        pr_err("PHY write queue full\n");
                show_error = 0;
                break;

        /* case SPIDER_NET_GRMDADRINT: not used. print a message */
        /* case SPIDER_NET_GRMARPINT: not used. print a message */
        /* case SPIDER_NET_GRMMPINT: not used. print a message */

        case SPIDER_NET_GDTDEN0INT:
                /* someone has set TX_DMA_EN to 0 */
                show_error = 0;
                break;

        case SPIDER_NET_GDDDEN0INT: /* fallthrough */
        case SPIDER_NET_GDCDEN0INT: /* fallthrough */
        case SPIDER_NET_GDBDEN0INT: /* fallthrough */
        case SPIDER_NET_GDADEN0INT:
                /* someone has set RX_DMA_EN to 0 */
                show_error = 0;
                break;

        /* RX interrupts */
        case SPIDER_NET_GDDFDCINT:
        case SPIDER_NET_GDCFDCINT:
        case SPIDER_NET_GDBFDCINT:
        case SPIDER_NET_GDAFDCINT:
        /* case SPIDER_NET_GDNMINT: not used. print a message */
        /* case SPIDER_NET_GCNMINT: not used. print a message */
        /* case SPIDER_NET_GBNMINT: not used. print a message */
        /* case SPIDER_NET_GANMINT: not used. print a message */
        /* case SPIDER_NET_GRFNMINT: not used. print a message */
                show_error = 0;
                break;

        /* TX interrupts */
        case SPIDER_NET_GDTFDCINT:
                show_error = 0;
                break;
        case SPIDER_NET_GTTEDINT:
                show_error = 0;
                break;
        case SPIDER_NET_GDTDCEINT:
                /* chain end. If a descriptor should be sent, kick off
                 * tx dma
                if (card->tx_chain.tail != card->tx_chain.head)
                        spider_net_kick_tx_dma(card);
                */
                show_error = 0;
                break;

        /* case SPIDER_NET_G1TMCNTINT: not used. print a message */
        /* case SPIDER_NET_GFREECNTINT: not used. print a message */
        }

        /* check GHIINT1STS ************************************/
        if (error_reg1)
                for (i = 0; i < 32; i++)
                        if (error_reg1 & (1<<i))
                                switch (i)
        {
        case SPIDER_NET_GTMFLLINT:
                if (netif_msg_intr(card) && net_ratelimit())
                        pr_err("Spider TX RAM full\n");
                show_error = 0;
                break;
        case SPIDER_NET_GRFDFLLINT: /* fallthrough */
        case SPIDER_NET_GRFCFLLINT: /* fallthrough */
        case SPIDER_NET_GRFBFLLINT: /* fallthrough */
        case SPIDER_NET_GRFAFLLINT: /* fallthrough */
        case SPIDER_NET_GRMFLLINT:
                if (netif_msg_intr(card) && net_ratelimit())
                        pr_err("Spider RX RAM full, incoming packets "
                               "might be discarded!\n");
                spider_net_rx_irq_off(card);
                netif_rx_schedule(card->netdev);
                show_error = 0;
                break;

        /* case SPIDER_NET_GTMSHTINT: problem, print a message */
        case SPIDER_NET_GDTINVDINT:
                /* allrighty. tx from previous descr ok */
                show_error = 0;
                break;

        /* chain end */
        case SPIDER_NET_GDDDCEINT: /* fallthrough */
        case SPIDER_NET_GDCDCEINT: /* fallthrough */
        case SPIDER_NET_GDBDCEINT: /* fallthrough */
        case SPIDER_NET_GDADCEINT:
                if (netif_msg_intr(card) && net_ratelimit())
                        pr_err("got descriptor chain end interrupt, "
                               "restarting DMAC %c.\n",
                               'D'-(i-SPIDER_NET_GDDDCEINT)/3);
                spider_net_refill_rx_chain(card);
                spider_net_enable_rxdmac(card);
                show_error = 0;
                break;

        /* invalid descriptor */
        case SPIDER_NET_GDDINVDINT: /* fallthrough */
        case SPIDER_NET_GDCINVDINT: /* fallthrough */
        case SPIDER_NET_GDBINVDINT: /* fallthrough */
        case SPIDER_NET_GDAINVDINT:
                /* could happen when rx chain is full */
                spider_net_refill_rx_chain(card);
                spider_net_enable_rxdmac(card);
                show_error = 0;
                break;

        /* case SPIDER_NET_GDTRSERINT: problem, print a message */
        /* case SPIDER_NET_GDDRSERINT: problem, print a message */
        /* case SPIDER_NET_GDCRSERINT: problem, print a message */
        /* case SPIDER_NET_GDBRSERINT: problem, print a message */
        /* case SPIDER_NET_GDARSERINT: problem, print a message */
        /* case SPIDER_NET_GDSERINT: problem, print a message */
        /* case SPIDER_NET_GDTPTERINT: problem, print a message */
        /* case SPIDER_NET_GDDPTERINT: problem, print a message */
        /* case SPIDER_NET_GDCPTERINT: problem, print a message */
        /* case SPIDER_NET_GDBPTERINT: problem, print a message */
        /* case SPIDER_NET_GDAPTERINT: problem, print a message */
        default:
                show_error = 1;
                break;
        }

        /* check GHIINT2STS ************************************/
        if (error_reg2)
                for (i = 0; i < 32; i++)
                        if (error_reg2 & (1<<i))
                                switch (i)
        {
        /* there is nothing we can (want  to) do at this time. Log a
         * message, we can switch on and off the specific values later on
        case SPIDER_NET_GPROPERINT:
        case SPIDER_NET_GMCTCRSNGINT:
        case SPIDER_NET_GMCTLCOLINT:
        case SPIDER_NET_GMCTTMOTINT:
        case SPIDER_NET_GMCRCAERINT:
        case SPIDER_NET_GMCRCALERINT:
        case SPIDER_NET_GMCRALNERINT:
        case SPIDER_NET_GMCROVRINT:
        case SPIDER_NET_GMCRRNTINT:
        case SPIDER_NET_GMCRRXERINT:
        case SPIDER_NET_GTITCSERINT:
        case SPIDER_NET_GTIFMTERINT:
        case SPIDER_NET_GTIPKTRVKINT:
        case SPIDER_NET_GTISPINGINT:
        case SPIDER_NET_GTISADNGINT:
        case SPIDER_NET_GTISPDNGINT:
        case SPIDER_NET_GRIFMTERINT:
        case SPIDER_NET_GRIPKTRVKINT:
        case SPIDER_NET_GRISPINGINT:
        case SPIDER_NET_GRISADNGINT:
        case SPIDER_NET_GRISPDNGINT:
                break;
        */
                default:
                        break;
        }

        if ((show_error) && (netif_msg_intr(card)) && net_ratelimit())
                pr_err("Got error interrupt on %s, GHIINT0STS = 0x%08x, "
                       "GHIINT1STS = 0x%08x, GHIINT2STS = 0x%08x\n",
                       card->netdev->name,
                       status_reg, error_reg1, error_reg2);

        /* clear interrupt sources */
        spider_net_write_reg(card, SPIDER_NET_GHIINT1STS, error_reg1);
        spider_net_write_reg(card, SPIDER_NET_GHIINT2STS, error_reg2);
}

/**
 * spider_net_interrupt - interrupt handler for spider_net
 * @irq: interupt number
 * @ptr: pointer to net_device
 * @regs: PU registers
 *
 * returns IRQ_HANDLED, if interrupt was for driver, or IRQ_NONE, if no
 * interrupt found raised by card.
 *
 * This is the interrupt handler, that turns off
 * interrupts for this device and makes the stack poll the driver
 */
static irqreturn_t
spider_net_interrupt(int irq, void *ptr)
{
        struct net_device *netdev = ptr;
        struct spider_net_card *card = netdev_priv(netdev);
        u32 status_reg;

        status_reg = spider_net_read_reg(card, SPIDER_NET_GHIINT0STS);

        if (!status_reg)
                return IRQ_NONE;

        if (status_reg & SPIDER_NET_RXINT ) {
                spider_net_rx_irq_off(card);
                netif_rx_schedule(netdev);
        }
        if (status_reg & SPIDER_NET_TXINT)
                netif_rx_schedule(netdev);

        if (status_reg & SPIDER_NET_ERRINT )
                spider_net_handle_error_irq(card, status_reg);

        /* clear interrupt sources */
        spider_net_write_reg(card, SPIDER_NET_GHIINT0STS, status_reg);

        return IRQ_HANDLED;
}

#ifdef CONFIG_NET_POLL_CONTROLLER
/**
 * spider_net_poll_controller - artificial interrupt for netconsole etc.
 * @netdev: interface device structure
 *
 * see Documentation/networking/netconsole.txt
 */
static void
spider_net_poll_controller(struct net_device *netdev)
{
        disable_irq(netdev->irq);
        spider_net_interrupt(netdev->irq, netdev);
        enable_irq(netdev->irq);
}
#endif /* CONFIG_NET_POLL_CONTROLLER */

/**
 * spider_net_init_card - initializes the card
 * @card: card structure
 *
 * spider_net_init_card initializes the card so that other registers can
 * be used
 */
static void
spider_net_init_card(struct spider_net_card *card)
{
        spider_net_write_reg(card, SPIDER_NET_CKRCTRL,
                             SPIDER_NET_CKRCTRL_STOP_VALUE);

        spider_net_write_reg(card, SPIDER_NET_CKRCTRL,
                             SPIDER_NET_CKRCTRL_RUN_VALUE);
}

/**
 * spider_net_enable_card - enables the card by setting all kinds of regs
 * @card: card structure
 *
 * spider_net_enable_card sets a lot of SMMIO registers to enable the device
 */
static void
spider_net_enable_card(struct spider_net_card *card)
{
        int i;
        /* the following array consists of (register),(value) pairs
         * that are set in this function. A register of 0 ends the list */
        u32 regs[][2] = {
                { SPIDER_NET_GRESUMINTNUM, 0 },
                { SPIDER_NET_GREINTNUM, 0 },

                /* set interrupt frame number registers */
                /* clear the single DMA engine registers first */
                { SPIDER_NET_GFAFRMNUM, SPIDER_NET_GFXFRAMES_VALUE },
                { SPIDER_NET_GFBFRMNUM, SPIDER_NET_GFXFRAMES_VALUE },
                { SPIDER_NET_GFCFRMNUM, SPIDER_NET_GFXFRAMES_VALUE },
                { SPIDER_NET_GFDFRMNUM, SPIDER_NET_GFXFRAMES_VALUE },
                /* then set, what we really need */
                { SPIDER_NET_GFFRMNUM, SPIDER_NET_FRAMENUM_VALUE },

                /* timer counter registers and stuff */
                { SPIDER_NET_GFREECNNUM, 0 },
                { SPIDER_NET_GONETIMENUM, 0 },
                { SPIDER_NET_GTOUTFRMNUM, 0 },

                /* RX mode setting */
                { SPIDER_NET_GRXMDSET, SPIDER_NET_RXMODE_VALUE },
                /* TX mode setting */
                { SPIDER_NET_GTXMDSET, SPIDER_NET_TXMODE_VALUE },
                /* IPSEC mode setting */
                { SPIDER_NET_GIPSECINIT, SPIDER_NET_IPSECINIT_VALUE },

                { SPIDER_NET_GFTRESTRT, SPIDER_NET_RESTART_VALUE },

                { SPIDER_NET_GMRWOLCTRL, 0 },
                { SPIDER_NET_GTESTMD, 0x10000000 },
                { SPIDER_NET_GTTQMSK, 0x00400040 },

                { SPIDER_NET_GMACINTEN, 0 },

                /* flow control stuff */
                { SPIDER_NET_GMACAPAUSE, SPIDER_NET_MACAPAUSE_VALUE },
                { SPIDER_NET_GMACTXPAUSE, SPIDER_NET_TXPAUSE_VALUE },

                { SPIDER_NET_GMACBSTLMT, SPIDER_NET_BURSTLMT_VALUE },
                { 0, 0}
        };

        i = 0;
        while (regs[i][0]) {
                spider_net_write_reg(card, regs[i][0], regs[i][1]);
                i++;
        }

        /* clear unicast filter table entries 1 to 14 */
        for (i = 1; i <= 14; i++) {
                spider_net_write_reg(card,
                                     SPIDER_NET_GMRUAFILnR + i * 8,
                                     0x00080000);
                spider_net_write_reg(card,
                                     SPIDER_NET_GMRUAFILnR + i * 8 + 4,
                                     0x00000000);
        }

        spider_net_write_reg(card, SPIDER_NET_GMRUA0FIL15R, 0x08080000);

        spider_net_write_reg(card, SPIDER_NET_ECMODE, SPIDER_NET_ECMODE_VALUE);

        /* set chain tail adress for RX chains and
         * enable DMA */
        spider_net_enable_rxchtails(card);
        spider_net_enable_rxdmac(card);

        spider_net_write_reg(card, SPIDER_NET_GRXDMAEN, SPIDER_NET_WOL_VALUE);

        spider_net_write_reg(card, SPIDER_NET_GMACLENLMT,
                             SPIDER_NET_LENLMT_VALUE);
        spider_net_write_reg(card, SPIDER_NET_GMACMODE,
                             SPIDER_NET_MACMODE_VALUE);
        spider_net_write_reg(card, SPIDER_NET_GMACOPEMD,
                             SPIDER_NET_OPMODE_VALUE);

        /* set interrupt mask registers */
        spider_net_write_reg(card, SPIDER_NET_GHIINT0MSK,
                             SPIDER_NET_INT0_MASK_VALUE);
        spider_net_write_reg(card, SPIDER_NET_GHIINT1MSK,
                             SPIDER_NET_INT1_MASK_VALUE);
        spider_net_write_reg(card, SPIDER_NET_GHIINT2MSK,
                             SPIDER_NET_INT2_MASK_VALUE);

        spider_net_write_reg(card, SPIDER_NET_GDTDMACCNTR,
                             SPIDER_NET_GDTBSTA);
}

/**
 * spider_net_open - called upon ifonfig up
 * @netdev: interface device structure
 *
 * returns 0 on success, <0 on failure
 *
 * spider_net_open allocates all the descriptors and memory needed for
 * operation, sets up multicast list and enables interrupts
 */
int
spider_net_open(struct net_device *netdev)
{
        struct spider_net_card *card = netdev_priv(netdev);
        struct spider_net_descr *descr;
        int result;

        result = spider_net_init_chain(card, &card->tx_chain);
        if (result)
                goto alloc_tx_failed;
        card->low_watermark = NULL;

        result = spider_net_init_chain(card, &card->rx_chain);
        if (result)
                goto alloc_rx_failed;

        /* Make a ring of of bus addresses */
        descr = card->rx_chain.ring;
        do {
                descr->next_descr_addr = descr->next->bus_addr;
                descr = descr->next;
        } while (descr != card->rx_chain.ring);

        /* Allocate rx skbs */
        if (spider_net_alloc_rx_skbs(card))
                goto alloc_skbs_failed;

        spider_net_set_multi(netdev);

        /* further enhancement: setup hw vlan, if needed */

        result = -EBUSY;
        if (request_irq(netdev->irq, spider_net_interrupt,
                             IRQF_SHARED, netdev->name, netdev))
                goto register_int_failed;

        spider_net_enable_card(card);

        netif_start_queue(netdev);
        netif_carrier_on(netdev);
        netif_poll_enable(netdev);

        return 0;

register_int_failed:
        spider_net_free_rx_chain_contents(card);
alloc_skbs_failed:
        spider_net_free_chain(card, &card->rx_chain);
alloc_rx_failed:
        spider_net_free_chain(card, &card->tx_chain);
alloc_tx_failed:
        return result;
}

/**
 * spider_net_setup_phy - setup PHY
 * @card: card structure
 *
 * returns 0 on success, <0 on failure
 *
 * spider_net_setup_phy is used as part of spider_net_probe. Sets
 * the PHY to 1000 Mbps
 **/
static int
spider_net_setup_phy(struct spider_net_card *card)
{
        struct mii_phy *phy = &card->phy;

        spider_net_write_reg(card, SPIDER_NET_GDTDMASEL,
                             SPIDER_NET_DMASEL_VALUE);
        spider_net_write_reg(card, SPIDER_NET_GPCCTRL,
                             SPIDER_NET_PHY_CTRL_VALUE);
        phy->mii_id = 1;
        phy->dev = card->netdev;
        phy->mdio_read = spider_net_read_phy;
        phy->mdio_write = spider_net_write_phy;

        mii_phy_probe(phy, phy->mii_id);

        if (phy->def->ops->setup_forced)
                phy->def->ops->setup_forced(phy, SPEED_1000, DUPLEX_FULL);

        phy->def->ops->enable_fiber(phy);

        phy->def->ops->read_link(phy);
        pr_info("Found %s with %i Mbps, %s-duplex.\n", phy->def->name,
                phy->speed, phy->duplex==1 ? "Full" : "Half");

        return 0;
}

/**
 * spider_net_download_firmware - loads firmware into the adapter
 * @card: card structure
 * @firmware_ptr: pointer to firmware data
 *
 * spider_net_download_firmware loads the firmware data into the
 * adapter. It assumes the length etc. to be allright.
 */
static int
spider_net_download_firmware(struct spider_net_card *card,
                             const void *firmware_ptr)
{
        int sequencer, i;
        const u32 *fw_ptr = firmware_ptr;

        /* stop sequencers */
        spider_net_write_reg(card, SPIDER_NET_GSINIT,
                             SPIDER_NET_STOP_SEQ_VALUE);

        for (sequencer = 0; sequencer < SPIDER_NET_FIRMWARE_SEQS;
             sequencer++) {
                spider_net_write_reg(card,
                                     SPIDER_NET_GSnPRGADR + sequencer * 8, 0);
                for (i = 0; i < SPIDER_NET_FIRMWARE_SEQWORDS; i++) {
                        spider_net_write_reg(card, SPIDER_NET_GSnPRGDAT +
                                             sequencer * 8, *fw_ptr);
                        fw_ptr++;
                }
        }

        if (spider_net_read_reg(card, SPIDER_NET_GSINIT))
                return -EIO;

        spider_net_write_reg(card, SPIDER_NET_GSINIT,
                             SPIDER_NET_RUN_SEQ_VALUE);

        return 0;
}

/**
 * spider_net_init_firmware - reads in firmware parts
 * @card: card structure
 *
 * Returns 0 on success, <0 on failure
 *
 * spider_net_init_firmware opens the sequencer firmware and does some basic
 * checks. This function opens and releases the firmware structure. A call
 * to download the firmware is performed before the release.
 *
 * Firmware format
 * ===============
 * spider_fw.bin is expected to be a file containing 6*1024*4 bytes, 4k being
 * the program for each sequencer. Use the command
 *    tail -q -n +2 Seq_code1_0x088.txt Seq_code2_0x090.txt              \
 *         Seq_code3_0x098.txt Seq_code4_0x0A0.txt Seq_code5_0x0A8.txt   \
 *         Seq_code6_0x0B0.txt | xxd -r -p -c4 > spider_fw.bin
 *
 * to generate spider_fw.bin, if you have sequencer programs with something
 * like the following contents for each sequencer:
 *    <ONE LINE COMMENT>
 *    <FIRST 4-BYTES-WORD FOR SEQUENCER>
 *    <SECOND 4-BYTES-WORD FOR SEQUENCER>
 *     ...
 *    <1024th 4-BYTES-WORD FOR SEQUENCER>
 */
static int
spider_net_init_firmware(struct spider_net_card *card)
{
        struct firmware *firmware = NULL;
        struct device_node *dn;
        const u8 *fw_prop = NULL;
        int err = -ENOENT;
        int fw_size;

        if (request_firmware((const struct firmware **)&firmware,
                             SPIDER_NET_FIRMWARE_NAME, &card->pdev->dev) == 0) {
                if ( (firmware->size != SPIDER_NET_FIRMWARE_LEN) &&
                     netif_msg_probe(card) ) {
                        pr_err("Incorrect size of spidernet firmware in " \
                               "filesystem. Looking in host firmware...\n");
                        goto try_host_fw;
                }
                err = spider_net_download_firmware(card, firmware->data);

                release_firmware(firmware);
                if (err)
                        goto try_host_fw;

                goto done;
        }

try_host_fw:
        dn = pci_device_to_OF_node(card->pdev);
        if (!dn)
                goto out_err;

        fw_prop = get_property(dn, "firmware", &fw_size);
        if (!fw_prop)
                goto out_err;

        if ( (fw_size != SPIDER_NET_FIRMWARE_LEN) &&
             netif_msg_probe(card) ) {
                pr_err("Incorrect size of spidernet firmware in " \
                       "host firmware\n");
                goto done;
        }

        err = spider_net_download_firmware(card, fw_prop);

done:
        return err;
out_err:
        if (netif_msg_probe(card))
                pr_err("Couldn't find spidernet firmware in filesystem " \
                       "or host firmware\n");
        return err;
}

/**
 * spider_net_workaround_rxramfull - work around firmware bug
 * @card: card structure
 *
 * no return value
 **/
static void
spider_net_workaround_rxramfull(struct spider_net_card *card)
{
        int i, sequencer = 0;

        /* cancel reset */
        spider_net_write_reg(card, SPIDER_NET_CKRCTRL,
                             SPIDER_NET_CKRCTRL_RUN_VALUE);

        /* empty sequencer data */
        for (sequencer = 0; sequencer < SPIDER_NET_FIRMWARE_SEQS;
             sequencer++) {
                spider_net_write_reg(card, SPIDER_NET_GSnPRGADR +
                                     sequencer * 8, 0x0);
                for (i = 0; i < SPIDER_NET_FIRMWARE_SEQWORDS; i++) {
                        spider_net_write_reg(card, SPIDER_NET_GSnPRGDAT +
                                             sequencer * 8, 0x0);
                }
        }

        /* set sequencer operation */
        spider_net_write_reg(card, SPIDER_NET_GSINIT, 0x000000fe);

        /* reset */
        spider_net_write_reg(card, SPIDER_NET_CKRCTRL,
                             SPIDER_NET_CKRCTRL_STOP_VALUE);
}

/**
 * spider_net_stop - called upon ifconfig down
 * @netdev: interface device structure
 *
 * always returns 0
 */
int
spider_net_stop(struct net_device *netdev)
{
        struct spider_net_card *card = netdev_priv(netdev);

        netif_poll_disable(netdev);
        netif_carrier_off(netdev);
        netif_stop_queue(netdev);
        del_timer_sync(&card->tx_timer);

        /* disable/mask all interrupts */
        spider_net_write_reg(card, SPIDER_NET_GHIINT0MSK, 0);
        spider_net_write_reg(card, SPIDER_NET_GHIINT1MSK, 0);
        spider_net_write_reg(card, SPIDER_NET_GHIINT2MSK, 0);

        /* free_irq(netdev->irq, netdev);*/
        free_irq(to_pci_dev(netdev->class_dev.dev)->irq, netdev);

        spider_net_write_reg(card, SPIDER_NET_GDTDMACCNTR,
                             SPIDER_NET_DMA_TX_FEND_VALUE);

        /* turn off DMA, force end */
        spider_net_disable_rxdmac(card);

        /* release chains */
        spider_net_release_tx_chain(card, 1);
        spider_net_free_rx_chain_contents(card);

        spider_net_free_rx_chain_contents(card);

        spider_net_free_chain(card, &card->tx_chain);
        spider_net_free_chain(card, &card->rx_chain);

        return 0;
}

/**
 * spider_net_tx_timeout_task - task scheduled by the watchdog timeout
 * function (to be called not under interrupt status)
 * @data: data, is interface device structure
 *
 * called as task when tx hangs, resets interface (if interface is up)
 */
static void
spider_net_tx_timeout_task(struct work_struct *work)
{
        struct spider_net_card *card =
                container_of(work, struct spider_net_card, tx_timeout_task);
        struct net_device *netdev = card->netdev;

        if (!(netdev->flags & IFF_UP))
                goto out;

        netif_device_detach(netdev);
        spider_net_stop(netdev);

        spider_net_workaround_rxramfull(card);
        spider_net_init_card(card);

        if (spider_net_setup_phy(card))
                goto out;
        if (spider_net_init_firmware(card))
                goto out;

        spider_net_open(netdev);
        spider_net_kick_tx_dma(card);
        netif_device_attach(netdev);

out:
        atomic_dec(&card->tx_timeout_task_counter);
}

/**
 * spider_net_tx_timeout - called when the tx timeout watchdog kicks in.
 * @netdev: interface device structure
 *
 * called, if tx hangs. Schedules a task that resets the interface
 */
static void
spider_net_tx_timeout(struct net_device *netdev)
{
        struct spider_net_card *card;

        card = netdev_priv(netdev);
        atomic_inc(&card->tx_timeout_task_counter);
        if (netdev->flags & IFF_UP)
                schedule_work(&card->tx_timeout_task);
        else
                atomic_dec(&card->tx_timeout_task_counter);
        card->spider_stats.tx_timeouts++;
}

/**
 * spider_net_setup_netdev_ops - initialization of net_device operations
 * @netdev: net_device structure
 *
 * fills out function pointers in the net_device structure
 */
static void
spider_net_setup_netdev_ops(struct net_device *netdev)
{
        netdev->open = &spider_net_open;
        netdev->stop = &spider_net_stop;
        netdev->hard_start_xmit = &spider_net_xmit;
        netdev->get_stats = &spider_net_get_stats;
        netdev->set_multicast_list = &spider_net_set_multi;
        netdev->set_mac_address = &spider_net_set_mac;
        netdev->change_mtu = &spider_net_change_mtu;
        netdev->do_ioctl = &spider_net_do_ioctl;
        /* tx watchdog */
        netdev->tx_timeout = &spider_net_tx_timeout;
        netdev->watchdog_timeo = SPIDER_NET_WATCHDOG_TIMEOUT;
        /* NAPI */
        netdev->poll = &spider_net_poll;
        netdev->weight = SPIDER_NET_NAPI_WEIGHT;
        /* HW VLAN */
        netdev->vlan_rx_register = &spider_net_vlan_rx_reg;
        netdev->vlan_rx_add_vid = &spider_net_vlan_rx_add;
        netdev->vlan_rx_kill_vid = &spider_net_vlan_rx_kill;
#ifdef CONFIG_NET_POLL_CONTROLLER
        /* poll controller */
        netdev->poll_controller = &spider_net_poll_controller;
#endif /* CONFIG_NET_POLL_CONTROLLER */
        /* ethtool ops */
        netdev->ethtool_ops = &spider_net_ethtool_ops;
}

/**
 * spider_net_setup_netdev - initialization of net_device
 * @card: card structure
 *
 * Returns 0 on success or <0 on failure
 *
 * spider_net_setup_netdev initializes the net_device structure
 **/
static int
spider_net_setup_netdev(struct spider_net_card *card)
{
        int result;
        struct net_device *netdev = card->netdev;
        struct device_node *dn;
        struct sockaddr addr;
        const u8 *mac;

        SET_MODULE_OWNER(netdev);
        SET_NETDEV_DEV(netdev, &card->pdev->dev);

        pci_set_drvdata(card->pdev, netdev);

        init_timer(&card->tx_timer);
        card->tx_timer.function =
                (void (*)(unsigned long)) spider_net_cleanup_tx_ring;
        card->tx_timer.data = (unsigned long) card;
        netdev->irq = card->pdev->irq;

        card->options.rx_csum = SPIDER_NET_RX_CSUM_DEFAULT;

        card->tx_chain.num_desc = tx_descriptors;
        card->rx_chain.num_desc = rx_descriptors;

        spider_net_setup_netdev_ops(netdev);

        netdev->features = NETIF_F_HW_CSUM | NETIF_F_LLTX;
        /* some time: NETIF_F_HW_VLAN_TX | NETIF_F_HW_VLAN_RX |
         *              NETIF_F_HW_VLAN_FILTER */

        netdev->irq = card->pdev->irq;

        dn = pci_device_to_OF_node(card->pdev);
        if (!dn)
                return -EIO;

        mac = get_property(dn, "local-mac-address", NULL);
        if (!mac)
                return -EIO;
        memcpy(addr.sa_data, mac, ETH_ALEN);

        result = spider_net_set_mac(netdev, &addr);
        if ((result) && (netif_msg_probe(card)))
                pr_err("Failed to set MAC address: %i\n", result);

        result = register_netdev(netdev);
        if (result) {
                if (netif_msg_probe(card))
                        pr_err("Couldn't register net_device: %i\n",
                                  result);
                return result;
        }

        if (netif_msg_probe(card))
                pr_info("Initialized device %s.\n", netdev->name);

        return 0;
}

/**
 * spider_net_alloc_card - allocates net_device and card structure
 *
 * returns the card structure or NULL in case of errors
 *
 * the card and net_device structures are linked to each other
 */
static struct spider_net_card *
spider_net_alloc_card(void)
{
        struct net_device *netdev;
        struct spider_net_card *card;

        netdev = alloc_etherdev(sizeof(struct spider_net_card));
        if (!netdev)
                return NULL;

        card = netdev_priv(netdev);
        card->netdev = netdev;
        card->msg_enable = SPIDER_NET_DEFAULT_MSG;
        INIT_WORK(&card->tx_timeout_task, spider_net_tx_timeout_task);
        init_waitqueue_head(&card->waitq);
        atomic_set(&card->tx_timeout_task_counter, 0);

        return card;
}

/**
 * spider_net_undo_pci_setup - releases PCI ressources
 * @card: card structure
 *
 * spider_net_undo_pci_setup releases the mapped regions
 */
static void
spider_net_undo_pci_setup(struct spider_net_card *card)
{
        iounmap(card->regs);
        pci_release_regions(card->pdev);
}

/**
 * spider_net_setup_pci_dev - sets up the device in terms of PCI operations
 * @card: card structure
 * @pdev: PCI device
 *
 * Returns the card structure or NULL if any errors occur
 *
 * spider_net_setup_pci_dev initializes pdev and together with the
 * functions called in spider_net_open configures the device so that
 * data can be transferred over it
 * The net_device structure is attached to the card structure, if the
 * function returns without error.
 **/
static struct spider_net_card *
spider_net_setup_pci_dev(struct pci_dev *pdev)
{
        struct spider_net_card *card;
        unsigned long mmio_start, mmio_len;

        if (pci_enable_device(pdev)) {
                pr_err("Couldn't enable PCI device\n");
                return NULL;
        }

        if (!(pci_resource_flags(pdev, 0) & IORESOURCE_MEM)) {
                pr_err("Couldn't find proper PCI device base address.\n");
                goto out_disable_dev;
        }

        if (pci_request_regions(pdev, spider_net_driver_name)) {
                pr_err("Couldn't obtain PCI resources, aborting.\n");
                goto out_disable_dev;
        }

        pci_set_master(pdev);

        card = spider_net_alloc_card();
        if (!card) {
                pr_err("Couldn't allocate net_device structure, "
                          "aborting.\n");
                goto out_release_regions;
        }
        card->pdev = pdev;

        /* fetch base address and length of first resource */
        mmio_start = pci_resource_start(pdev, 0);
        mmio_len = pci_resource_len(pdev, 0);

        card->netdev->mem_start = mmio_start;
        card->netdev->mem_end = mmio_start + mmio_len;
        card->regs = ioremap(mmio_start, mmio_len);

        if (!card->regs) {
                pr_err("Couldn't obtain PCI resources, aborting.\n");
                goto out_release_regions;
        }

        return card;

out_release_regions:
        pci_release_regions(pdev);
out_disable_dev:
        pci_disable_device(pdev);
        pci_set_drvdata(pdev, NULL);
        return NULL;
}

/**
 * spider_net_probe - initialization of a device
 * @pdev: PCI device
 * @ent: entry in the device id list
 *
 * Returns 0 on success, <0 on failure
 *
 * spider_net_probe initializes pdev and registers a net_device
 * structure for it. After that, the device can be ifconfig'ed up
 **/
static int __devinit
spider_net_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
{
        int err = -EIO;
        struct spider_net_card *card;

        card = spider_net_setup_pci_dev(pdev);
        if (!card)
                goto out;

        spider_net_workaround_rxramfull(card);
        spider_net_init_card(card);

        err = spider_net_setup_phy(card);
        if (err)
                goto out_undo_pci;

        err = spider_net_init_firmware(card);
        if (err)
                goto out_undo_pci;

        err = spider_net_setup_netdev(card);
        if (err)
                goto out_undo_pci;

        return 0;

out_undo_pci:
        spider_net_undo_pci_setup(card);
        free_netdev(card->netdev);
out:
        return err;
}

/**
 * spider_net_remove - removal of a device
 * @pdev: PCI device
 *
 * Returns 0 on success, <0 on failure
 *
 * spider_net_remove is called to remove the device and unregisters the
 * net_device
 **/
static void __devexit
spider_net_remove(struct pci_dev *pdev)
{
        struct net_device *netdev;
        struct spider_net_card *card;

        netdev = pci_get_drvdata(pdev);
        card = netdev_priv(netdev);

        wait_event(card->waitq,
                   atomic_read(&card->tx_timeout_task_counter) == 0);

        unregister_netdev(netdev);

        /* switch off card */
        spider_net_write_reg(card, SPIDER_NET_CKRCTRL,
                             SPIDER_NET_CKRCTRL_STOP_VALUE);
        spider_net_write_reg(card, SPIDER_NET_CKRCTRL,
                             SPIDER_NET_CKRCTRL_RUN_VALUE);

        spider_net_undo_pci_setup(card);
        free_netdev(netdev);
}

static struct pci_driver spider_net_driver = {
        .name           = spider_net_driver_name,
        .id_table       = spider_net_pci_tbl,
        .probe          = spider_net_probe,
        .remove         = __devexit_p(spider_net_remove)
};

/**
 * spider_net_init - init function when the driver is loaded
 *
 * spider_net_init registers the device driver
 */
static int __init spider_net_init(void)
{
        printk(KERN_INFO "Spidernet version %s.\n", VERSION);

        if (rx_descriptors < SPIDER_NET_RX_DESCRIPTORS_MIN) {
                rx_descriptors = SPIDER_NET_RX_DESCRIPTORS_MIN;
                pr_info("adjusting rx descriptors to %i.\n", rx_descriptors);
        }
        if (rx_descriptors > SPIDER_NET_RX_DESCRIPTORS_MAX) {
                rx_descriptors = SPIDER_NET_RX_DESCRIPTORS_MAX;
                pr_info("adjusting rx descriptors to %i.\n", rx_descriptors);
        }
        if (tx_descriptors < SPIDER_NET_TX_DESCRIPTORS_MIN) {
                tx_descriptors = SPIDER_NET_TX_DESCRIPTORS_MIN;
                pr_info("adjusting tx descriptors to %i.\n", tx_descriptors);
        }
        if (tx_descriptors > SPIDER_NET_TX_DESCRIPTORS_MAX) {
                tx_descriptors = SPIDER_NET_TX_DESCRIPTORS_MAX;
                pr_info("adjusting tx descriptors to %i.\n", tx_descriptors);
        }

        return pci_register_driver(&spider_net_driver);
}

/**
 * spider_net_cleanup - exit function when driver is unloaded
 *
 * spider_net_cleanup unregisters the device driver
 */
static void __exit spider_net_cleanup(void)
{
        pci_unregister_driver(&spider_net_driver);
}

module_init(spider_net_init);
module_exit(spider_net_cleanup);