static const char version[] = "de600.c: $Revision: 1.41-2.5 $,  Bjorn Ekwall (bj0rn@blox.se)\n";
/*
 *      de600.c
 *
 *      Linux driver for the D-Link DE-600 Ethernet pocket adapter.
 *
 *      Portions (C) Copyright 1993, 1994 by Bjorn Ekwall
 *      The Author may be reached as bj0rn@blox.se
 *
 *      Based on adapter information gathered from DE600.ASM by D-Link Inc.,
 *      as included on disk C in the v.2.11 of PC/TCP from FTP Software.
 *      For DE600.asm:
 *              Portions (C) Copyright 1990 D-Link, Inc.
 *              Copyright, 1988-1992, Russell Nelson, Crynwr Software
 *
 *      Adapted to the sample network driver core for linux,
 *      written by: Donald Becker <becker@super.org>
 *              (Now at <becker@scyld.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.
 *
 **************************************************************/

/* Add more time here if your adapter won't work OK: */
#define DE600_SLOW_DOWN udelay(delay_time)

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/string.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/in.h>
#include <asm/system.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>

#include <asm/io.h>

#include "de600.h"

static unsigned int check_lost = 1;
module_param(check_lost, bool, 0);
MODULE_PARM_DESC(check_lost, "If set then check for unplugged de600");

static unsigned int delay_time = 10;
module_param(delay_time, int, 0);
MODULE_PARM_DESC(delay_time, "DE-600 deley on I/O in microseconds");


/*
 * D-Link driver variables:
 */

static volatile int             rx_page;

#define TX_PAGES 2
static volatile int             tx_fifo[TX_PAGES];
static volatile int             tx_fifo_in;
static volatile int             tx_fifo_out;
static volatile int             free_tx_pages = TX_PAGES;
static int                      was_down;
static DEFINE_SPINLOCK(de600_lock);

static inline u8 de600_read_status(struct net_device *dev)
{
        u8 status;

        outb_p(STATUS, DATA_PORT);
        status = inb(STATUS_PORT);
        outb_p(NULL_COMMAND | HI_NIBBLE, DATA_PORT);

        return status;
}

static inline u8 de600_read_byte(unsigned char type, struct net_device *dev)
{
        /* dev used by macros */
        u8 lo;
        outb_p((type), DATA_PORT);
        lo = ((unsigned char)inb(STATUS_PORT)) >> 4;
        outb_p((type) | HI_NIBBLE, DATA_PORT);
        return ((unsigned char)inb(STATUS_PORT) & (unsigned char)0xf0) | lo;
}

/*
 * Open/initialize the board.  This is called (in the current kernel)
 * after booting when 'ifconfig <dev->name> $IP_ADDR' is run (in rc.inet1).
 *
 * This routine should set everything up anew at each open, even
 * registers that "should" only need to be set once at boot, so that
 * there is a non-reboot way to recover if something goes wrong.
 */

static int de600_open(struct net_device *dev)
{
        unsigned long flags;
        int ret = request_irq(DE600_IRQ, de600_interrupt, 0, dev->name, dev);
        if (ret) {
                printk(KERN_ERR "%s: unable to get IRQ %d\n", dev->name, DE600_IRQ);
                return ret;
        }
        spin_lock_irqsave(&de600_lock, flags);
        ret = adapter_init(dev);
        spin_unlock_irqrestore(&de600_lock, flags);
        return ret;
}

/*
 * The inverse routine to de600_open().
 */

static int de600_close(struct net_device *dev)
{
        select_nic();
        rx_page = 0;
        de600_put_command(RESET);
        de600_put_command(STOP_RESET);
        de600_put_command(0);
        select_prn();
        free_irq(DE600_IRQ, dev);
        return 0;
}

static inline void trigger_interrupt(struct net_device *dev)
{
        de600_put_command(FLIP_IRQ);
        select_prn();
        DE600_SLOW_DOWN;
        select_nic();
        de600_put_command(0);
}

/*
 * Copy a buffer to the adapter transmit page memory.
 * Start sending.
 */

static int de600_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        unsigned long flags;
        int     transmit_from;
        int     len;
        int     tickssofar;
        u8      *buffer = skb->data;
        int     i;

        if (free_tx_pages <= 0) {       /* Do timeouts, to avoid hangs. */
                tickssofar = jiffies - dev->trans_start;
                if (tickssofar < 5)
                        return NETDEV_TX_BUSY;
                /* else */
                printk(KERN_WARNING "%s: transmit timed out (%d), %s?\n", dev->name, tickssofar, "network cable problem");
                /* Restart the adapter. */
                spin_lock_irqsave(&de600_lock, flags);
                if (adapter_init(dev)) {
                        spin_unlock_irqrestore(&de600_lock, flags);
                        return NETDEV_TX_BUSY;
                }
                spin_unlock_irqrestore(&de600_lock, flags);
        }

        /* Start real output */
        pr_debug("de600_start_xmit:len=%d, page %d/%d\n", skb->len, tx_fifo_in, free_tx_pages);

        if ((len = skb->len) < RUNT)
                len = RUNT;

        spin_lock_irqsave(&de600_lock, flags);
        select_nic();
        tx_fifo[tx_fifo_in] = transmit_from = tx_page_adr(tx_fifo_in) - len;
        tx_fifo_in = (tx_fifo_in + 1) % TX_PAGES; /* Next free tx page */

        if(check_lost)
        {
                /* This costs about 40 instructions per packet... */
                de600_setup_address(NODE_ADDRESS, RW_ADDR);
                de600_read_byte(READ_DATA, dev);
                if (was_down || (de600_read_byte(READ_DATA, dev) != 0xde)) {
                        if (adapter_init(dev)) {
                                spin_unlock_irqrestore(&de600_lock, flags);
                                return NETDEV_TX_BUSY;
                        }
                }
        }

        de600_setup_address(transmit_from, RW_ADDR);
        for (i = 0;  i < skb->len ; ++i, ++buffer)
                de600_put_byte(*buffer);
        for (; i < len; ++i)
                de600_put_byte(0);

        if (free_tx_pages-- == TX_PAGES) { /* No transmission going on */
                dev->trans_start = jiffies;
                netif_start_queue(dev); /* allow more packets into adapter */
                /* Send page and generate a faked interrupt */
                de600_setup_address(transmit_from, TX_ADDR);
                de600_put_command(TX_ENABLE);
        }
        else {
                if (free_tx_pages)
                        netif_start_queue(dev);
                else
                        netif_stop_queue(dev);
                select_prn();
        }
        spin_unlock_irqrestore(&de600_lock, flags);
        dev_kfree_skb(skb);
        return NETDEV_TX_OK;
}

/*
 * The typical workload of the driver:
 * Handle the network interface interrupts.
 */

static irqreturn_t de600_interrupt(int irq, void *dev_id)
{
        struct net_device       *dev = dev_id;
        u8              irq_status;
        int             retrig = 0;
        int             boguscount = 0;

        spin_lock(&de600_lock);

        select_nic();
        irq_status = de600_read_status(dev);

        do {
                pr_debug("de600_interrupt (%02X)\n", irq_status);

                if (irq_status & RX_GOOD)
                        de600_rx_intr(dev);
                else if (!(irq_status & RX_BUSY))
                        de600_put_command(RX_ENABLE);

                /* Any transmission in progress? */
                if (free_tx_pages < TX_PAGES)
                        retrig = de600_tx_intr(dev, irq_status);
                else
                        retrig = 0;

                irq_status = de600_read_status(dev);
        } while ( (irq_status & RX_GOOD) || ((++boguscount < 100) && retrig) );
        /*
         * Yeah, it _looks_ like busy waiting, smells like busy waiting
         * and I know it's not PC, but please, it will only occur once
         * in a while and then only for a loop or so (< 1ms for sure!)
         */

        /* Enable adapter interrupts */
        select_prn();
        if (retrig)
                trigger_interrupt(dev);
        spin_unlock(&de600_lock);
        return IRQ_HANDLED;
}

static int de600_tx_intr(struct net_device *dev, int irq_status)
{
        /*
         * Returns 1 if tx still not done
         */

        /* Check if current transmission is done yet */
        if (irq_status & TX_BUSY)
                return 1; /* tx not done, try again */

        /* else */
        /* If last transmission OK then bump fifo index */
        if (!(irq_status & TX_FAILED16)) {
                tx_fifo_out = (tx_fifo_out + 1) % TX_PAGES;
                ++free_tx_pages;
                dev->stats.tx_packets++;
                netif_wake_queue(dev);
        }

        /* More to send, or resend last packet? */
        if ((free_tx_pages < TX_PAGES) || (irq_status & TX_FAILED16)) {
                dev->trans_start = jiffies;
                de600_setup_address(tx_fifo[tx_fifo_out], TX_ADDR);
                de600_put_command(TX_ENABLE);
                return 1;
        }
        /* else */

        return 0;
}

/*
 * We have a good packet, get it out of the adapter.
 */
static void de600_rx_intr(struct net_device *dev)
{
        struct sk_buff  *skb;
        int             i;
        int             read_from;
        int             size;
        unsigned char   *buffer;

        /* Get size of received packet */
        size = de600_read_byte(RX_LEN, dev);    /* low byte */
        size += (de600_read_byte(RX_LEN, dev) << 8);    /* high byte */
        size -= 4;      /* Ignore trailing 4 CRC-bytes */

        /* Tell adapter where to store next incoming packet, enable receiver */
        read_from = rx_page_adr();
        next_rx_page();
        de600_put_command(RX_ENABLE);

        if ((size < 32)  ||  (size > 1535)) {
                printk(KERN_WARNING "%s: Bogus packet size %d.\n", dev->name, size);
                if (size > 10000)
                        adapter_init(dev);
                return;
        }

        skb = dev_alloc_skb(size+2);
        if (skb == NULL) {
                printk("%s: Couldn't allocate a sk_buff of size %d.\n", dev->name, size);
                return;
        }
        /* else */

        skb_reserve(skb,2);     /* Align */

        /* 'skb->data' points to the start of sk_buff data area. */
        buffer = skb_put(skb,size);

        /* copy the packet into the buffer */
        de600_setup_address(read_from, RW_ADDR);
        for (i = size; i > 0; --i, ++buffer)
                *buffer = de600_read_byte(READ_DATA, dev);

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

        netif_rx(skb);

        /* update stats */
        dev->stats.rx_packets++; /* count all receives */
        dev->stats.rx_bytes += size; /* count all received bytes */

        /*
         * If any worth-while packets have been received, netif_rx()
         * will work on them when we get to the tasklets.
         */
}

static const struct net_device_ops de600_netdev_ops = {
        .ndo_open               = de600_open,
        .ndo_stop               = de600_close,
        .ndo_start_xmit         = de600_start_xmit,
        .ndo_change_mtu         = eth_change_mtu,
        .ndo_set_mac_address    = eth_mac_addr,
        .ndo_validate_addr      = eth_validate_addr,
};


static struct net_device * __init de600_probe(void)
{
        int     i;
        struct net_device *dev;
        int err;

        dev = alloc_etherdev(0);
        if (!dev)
                return ERR_PTR(-ENOMEM);


        if (!request_region(DE600_IO, 3, "de600")) {
                printk(KERN_WARNING "DE600: port 0x%x busy\n", DE600_IO);
                err = -EBUSY;
                goto out;
        }

        printk(KERN_INFO "%s: D-Link DE-600 pocket adapter", dev->name);
        /* Alpha testers must have the version number to report bugs. */
        pr_debug("%s", version);

        /* probe for adapter */
        err = -ENODEV;
        rx_page = 0;
        select_nic();
        (void)de600_read_status(dev);
        de600_put_command(RESET);
        de600_put_command(STOP_RESET);
        if (de600_read_status(dev) & 0xf0) {
                printk(": not at I/O %#3x.\n", DATA_PORT);
                goto out1;
        }

        /*
         * Maybe we found one,
         * have to check if it is a D-Link DE-600 adapter...
         */

        /* Get the adapter ethernet address from the ROM */
        de600_setup_address(NODE_ADDRESS, RW_ADDR);
        for (i = 0; i < ETH_ALEN; i++) {
                dev->dev_addr[i] = de600_read_byte(READ_DATA, dev);
                dev->broadcast[i] = 0xff;
        }

        /* Check magic code */
        if ((dev->dev_addr[1] == 0xde) && (dev->dev_addr[2] == 0x15)) {
                /* OK, install real address */
                dev->dev_addr[0] = 0x00;
                dev->dev_addr[1] = 0x80;
                dev->dev_addr[2] = 0xc8;
                dev->dev_addr[3] &= 0x0f;
                dev->dev_addr[3] |= 0x70;
        } else {
                printk(" not identified in the printer port\n");
                goto out1;
        }

        printk(", Ethernet Address: %pM\n", dev->dev_addr);

        dev->netdev_ops = &de600_netdev_ops;

        dev->flags&=~IFF_MULTICAST;

        select_prn();

        err = register_netdev(dev);
        if (err)
                goto out1;

        return dev;

out1:
        release_region(DE600_IO, 3);
out:
        free_netdev(dev);
        return ERR_PTR(err);
}

static int adapter_init(struct net_device *dev)
{
        int     i;

        select_nic();
        rx_page = 0; /* used by RESET */
        de600_put_command(RESET);
        de600_put_command(STOP_RESET);

        /* Check if it is still there... */
        /* Get the some bytes of the adapter ethernet address from the ROM */
        de600_setup_address(NODE_ADDRESS, RW_ADDR);
        de600_read_byte(READ_DATA, dev);
        if ((de600_read_byte(READ_DATA, dev) != 0xde) ||
            (de600_read_byte(READ_DATA, dev) != 0x15)) {
        /* was: if (de600_read_status(dev) & 0xf0) { */
                printk("Something has happened to the DE-600!  Please check it and do a new ifconfig!\n");
                /* Goodbye, cruel world... */
                dev->flags &= ~IFF_UP;
                de600_close(dev);
                was_down = 1;
                netif_stop_queue(dev); /* Transmit busy...  */
                return 1; /* failed */
        }

        if (was_down) {
                printk(KERN_INFO "%s: Thanks, I feel much better now!\n", dev->name);
                was_down = 0;
        }

        tx_fifo_in = 0;
        tx_fifo_out = 0;
        free_tx_pages = TX_PAGES;


        /* set the ether address. */
        de600_setup_address(NODE_ADDRESS, RW_ADDR);
        for (i = 0; i < ETH_ALEN; i++)
                de600_put_byte(dev->dev_addr[i]);

        /* where to start saving incoming packets */
        rx_page = RX_BP | RX_BASE_PAGE;
        de600_setup_address(MEM_4K, RW_ADDR);
        /* Enable receiver */
        de600_put_command(RX_ENABLE);
        select_prn();

        netif_start_queue(dev);

        return 0; /* OK */
}

static struct net_device *de600_dev;

static int __init de600_init(void)
{
        de600_dev = de600_probe();
        if (IS_ERR(de600_dev))
                return PTR_ERR(de600_dev);
        return 0;
}

static void __exit de600_exit(void)
{
        unregister_netdev(de600_dev);
        release_region(DE600_IO, 3);
        free_netdev(de600_dev);
}

module_init(de600_init);
module_exit(de600_exit);

MODULE_LICENSE("GPL");