/* isa-skeleton.c: A network driver outline for linux.
 *
 *      Written 1993-94 by Donald Becker.
 *
 *      Copyright 1993 United States Government as represented by the
 *      Director, National Security Agency.
 *
 *      This software may be used and distributed according to the terms
 *      of the GNU General Public License, incorporated herein by reference.
 *
 *      The author may be reached as becker@scyld.com, or C/O
 *      Scyld Computing Corporation
 *      410 Severn Ave., Suite 210
 *      Annapolis MD 21403
 *
 *      This file is an outline for writing a network device driver for the
 *      the Linux operating system.
 *
 *      To write (or understand) a driver, have a look at the "loopback.c" file to
 *      get a feel of what is going on, and then use the code below as a skeleton
 *      for the new driver.
 *
 */

static const char *version =
        "isa-skeleton.c:v1.51 9/24/94 Donald Becker (becker@cesdis.gsfc.nasa.gov)\n";

/*
 *  Sources:
 *      List your sources of programming information to document that
 *      the driver is your own creation, and give due credit to others
 *      that contributed to the work. Remember that GNU project code
 *      cannot use proprietary or trade secret information. Interface
 *      definitions are generally considered non-copyrightable to the
 *      extent that the same names and structures must be used to be
 *      compatible.
 *
 *      Finally, keep in mind that the Linux kernel is has an API, not
 *      ABI. Proprietary object-code-only distributions are not permitted
 *      under the GPL.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/in.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/bitops.h>

#include <asm/system.h>
#include <asm/io.h>
#include <asm/dma.h>

/*
 * The name of the card. Is used for messages and in the requests for
 * io regions, irqs and dma channels
 */
static const char* cardname = "netcard";

/* First, a few definitions that the brave might change. */

/* A zero-terminated list of I/O addresses to be probed. */
static unsigned int netcard_portlist[] __initdata =
   { 0x200, 0x240, 0x280, 0x2C0, 0x300, 0x320, 0x340, 0};

/* use 0 for production, 1 for verification, >2 for debug */
#ifndef NET_DEBUG
#define NET_DEBUG 2
#endif
static unsigned int net_debug = NET_DEBUG;

/* The number of low I/O ports used by the ethercard. */
#define NETCARD_IO_EXTENT       32

#define MY_TX_TIMEOUT  ((400*HZ)/1000)

/* Information that need to be kept for each board. */
struct net_local {
        struct net_device_stats stats;
        long open_time;                 /* Useless example local info. */

        /* Tx control lock.  This protects the transmit buffer ring
         * state along with the "tx full" state of the driver.  This
         * means all netif_queue flow control actions are protected
         * by this lock as well.
         */
        spinlock_t lock;
};

/* The station (ethernet) address prefix, used for IDing the board. */
#define SA_ADDR0 0x00
#define SA_ADDR1 0x42
#define SA_ADDR2 0x65

/* Index to functions, as function prototypes. */

static int      netcard_probe1(struct net_device *dev, int ioaddr);
static int      net_open(struct net_device *dev);
static int      net_send_packet(struct sk_buff *skb, struct net_device *dev);
static irqreturn_t net_interrupt(int irq, void *dev_id);
static void     net_rx(struct net_device *dev);
static int      net_close(struct net_device *dev);
static struct   net_device_stats *net_get_stats(struct net_device *dev);
static void     set_multicast_list(struct net_device *dev);
static void     net_tx_timeout(struct net_device *dev);


/* Example routines you must write ;->. */
#define tx_done(dev) 1
static void     hardware_send_packet(short ioaddr, char *buf, int length);
static void     chipset_init(struct net_device *dev, int startp);

/*
 * Check for a network adaptor of this type, and return '0' iff one exists.
 * If dev->base_addr == 0, probe all likely locations.
 * If dev->base_addr == 1, always return failure.
 * If dev->base_addr == 2, allocate space for the device and return success
 * (detachable devices only).
 */
static int __init do_netcard_probe(struct net_device *dev)
{
        int i;
        int base_addr = dev->base_addr;
        int irq = dev->irq;

        if (base_addr > 0x1ff)    /* Check a single specified location. */
                return netcard_probe1(dev, base_addr);
        else if (base_addr != 0)  /* Don't probe at all. */
                return -ENXIO;

        for (i = 0; netcard_portlist[i]; i++) {
                int ioaddr = netcard_portlist[i];
                if (netcard_probe1(dev, ioaddr) == 0)
                        return 0;
                dev->irq = irq;
        }

        return -ENODEV;
}

static void cleanup_card(struct net_device *dev)
{
#ifdef jumpered_dma
        free_dma(dev->dma);
#endif
#ifdef jumpered_interrupts
        free_irq(dev->irq, dev);
#endif
        release_region(dev->base_addr, NETCARD_IO_EXTENT);
}

#ifndef MODULE
struct net_device * __init netcard_probe(int unit)
{
        struct net_device *dev = alloc_etherdev(sizeof(struct net_local));
        int err;

        if (!dev)
                return ERR_PTR(-ENOMEM);

        sprintf(dev->name, "eth%d", unit);
        netdev_boot_setup_check(dev);

        err = do_netcard_probe(dev);
        if (err)
                goto out;
        return dev;
out:
        free_netdev(dev);
        return ERR_PTR(err);
}
#endif

static const struct net_device_ops netcard_netdev_ops = {
        .ndo_open               = net_open,
        .ndo_stop               = net_close,
        .ndo_start_xmit         = net_send_packet,
        .ndo_get_stats          = net_get_stats,
        .ndo_set_multicast_list = set_multicast_list,
        .ndo_tx_timeout         = net_tx_timeout,
        .ndo_validate_addr      = eth_validate_addr,
        .ndo_set_mac_address    = eth_mac_addr,
        .ndo_change_mtu         = eth_change_mtu,
};

/*
 * This is the real probe routine. Linux has a history of friendly device
 * probes on the ISA bus. A good device probes avoids doing writes, and
 * verifies that the correct device exists and functions.
 */
static int __init netcard_probe1(struct net_device *dev, int ioaddr)
{
        struct net_local *np;
        static unsigned version_printed;
        int i;
        int err = -ENODEV;

        /* Grab the region so that no one else tries to probe our ioports. */
        if (!request_region(ioaddr, NETCARD_IO_EXTENT, cardname))
                return -EBUSY;

        /*
         * For ethernet adaptors the first three octets of the station address
         * contains the manufacturer's unique code. That might be a good probe
         * method. Ideally you would add additional checks.
         */
        if (inb(ioaddr + 0) != SA_ADDR0
                ||       inb(ioaddr + 1) != SA_ADDR1
                ||       inb(ioaddr + 2) != SA_ADDR2)
                goto out;

        if (net_debug  &&  version_printed++ == 0)
                printk(KERN_DEBUG "%s", version);

        printk(KERN_INFO "%s: %s found at %#3x, ", dev->name, cardname, ioaddr);

        /* Fill in the 'dev' fields. */
        dev->base_addr = ioaddr;

        /* Retrieve and print the ethernet address. */
        for (i = 0; i < 6; i++)
                dev->dev_addr[i] = inb(ioaddr + i);

        printk("%pM", dev->dev_addr);

        err = -EAGAIN;
#ifdef jumpered_interrupts
        /*
         * If this board has jumpered interrupts, allocate the interrupt
         * vector now. There is no point in waiting since no other device
         * can use the interrupt, and this marks the irq as busy. Jumpered
         * interrupts are typically not reported by the boards, and we must
         * used autoIRQ to find them.
         */

        if (dev->irq == -1)
                ;       /* Do nothing: a user-level program will set it. */
        else if (dev->irq < 2) {        /* "Auto-IRQ" */
                unsigned long irq_mask = probe_irq_on();
                /* Trigger an interrupt here. */

                dev->irq = probe_irq_off(irq_mask);
                if (net_debug >= 2)
                        printk(" autoirq is %d", dev->irq);
        } else if (dev->irq == 2)
                /*
                 * Fixup for users that don't know that IRQ 2 is really
                 * IRQ9, or don't know which one to set.
                 */
                dev->irq = 9;

        {
                int irqval = request_irq(dev->irq, &net_interrupt, 0, cardname, dev);
                if (irqval) {
                        printk("%s: unable to get IRQ %d (irqval=%d).\n",
                                   dev->name, dev->irq, irqval);
                        goto out;
                }
        }
#endif  /* jumpered interrupt */
#ifdef jumpered_dma
        /*
         * If we use a jumpered DMA channel, that should be probed for and
         * allocated here as well. See lance.c for an example.
         */
        if (dev->dma == 0) {
                if (request_dma(dev->dma, cardname)) {
                        printk("DMA %d allocation failed.\n", dev->dma);
                        goto out1;
                } else
                        printk(", assigned DMA %d.\n", dev->dma);
        } else {
                short dma_status, new_dma_status;

                /* Read the DMA channel status registers. */
                dma_status = ((inb(DMA1_STAT_REG) >> 4) & 0x0f) |
                        (inb(DMA2_STAT_REG) & 0xf0);
                /* Trigger a DMA request, perhaps pause a bit. */
                outw(0x1234, ioaddr + 8);
                /* Re-read the DMA status registers. */
                new_dma_status = ((inb(DMA1_STAT_REG) >> 4) & 0x0f) |
                        (inb(DMA2_STAT_REG) & 0xf0);
                /*
                 * Eliminate the old and floating requests,
                 * and DMA4 the cascade.
                 */
                new_dma_status ^= dma_status;
                new_dma_status &= ~0x10;
                for (i = 7; i > 0; i--)
                        if (test_bit(i, &new_dma_status)) {
                                dev->dma = i;
                                break;
                        }
                if (i <= 0) {
                        printk("DMA probe failed.\n");
                        goto out1;
                }
                if (request_dma(dev->dma, cardname)) {
                        printk("probed DMA %d allocation failed.\n", dev->dma);
                        goto out1;
                }
        }
#endif  /* jumpered DMA */

        np = netdev_priv(dev);
        spin_lock_init(&np->lock);

        dev->netdev_ops         = &netcard_netdev_ops;
        dev->watchdog_timeo     = MY_TX_TIMEOUT;

        err = register_netdev(dev);
        if (err)
                goto out2;
        return 0;
out2:
#ifdef jumpered_dma
        free_dma(dev->dma);
#endif
out1:
#ifdef jumpered_interrupts
        free_irq(dev->irq, dev);
#endif
out:
        release_region(base_addr, NETCARD_IO_EXTENT);
        return err;
}

static void net_tx_timeout(struct net_device *dev)
{
        struct net_local *np = netdev_priv(dev);

        printk(KERN_WARNING "%s: transmit timed out, %s?\n", dev->name,
               tx_done(dev) ? "IRQ conflict" : "network cable problem");

        /* Try to restart the adaptor. */
        chipset_init(dev, 1);

        np->stats.tx_errors++;

        /* If we have space available to accept new transmit
         * requests, wake up the queueing layer.  This would
         * be the case if the chipset_init() call above just
         * flushes out the tx queue and empties it.
         *
         * If instead, the tx queue is retained then the
         * netif_wake_queue() call should be placed in the
         * TX completion interrupt handler of the driver instead
         * of here.
         */
        if (!tx_full(dev))
                netif_wake_queue(dev);
}

/*
 * Open/initialize the board. This is called (in the current kernel)
 * sometime after booting when the 'ifconfig' program is run.
 *
 * 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 non-reboot way to recover if something goes wrong.
 */
static int
net_open(struct net_device *dev)
{
        struct net_local *np = netdev_priv(dev);
        int ioaddr = dev->base_addr;
        /*
         * This is used if the interrupt line can turned off (shared).
         * See 3c503.c for an example of selecting the IRQ at config-time.
         */
        if (request_irq(dev->irq, &net_interrupt, 0, cardname, dev)) {
                return -EAGAIN;
        }
        /*
         * Always allocate the DMA channel after the IRQ,
         * and clean up on failure.
         */
        if (request_dma(dev->dma, cardname)) {
                free_irq(dev->irq, dev);
                return -EAGAIN;
        }

        /* Reset the hardware here. Don't forget to set the station address. */
        chipset_init(dev, 1);
        outb(0x00, ioaddr);
        np->open_time = jiffies;

        /* We are now ready to accept transmit requeusts from
         * the queueing layer of the networking.
         */
        netif_start_queue(dev);

        return 0;
}

/* This will only be invoked if your driver is _not_ in XOFF state.
 * What this means is that you need not check it, and that this
 * invariant will hold if you make sure that the netif_*_queue()
 * calls are done at the proper times.
 */
static int net_send_packet(struct sk_buff *skb, struct net_device *dev)
{
        struct net_local *np = netdev_priv(dev);
        int ioaddr = dev->base_addr;
        short length = ETH_ZLEN < skb->len ? skb->len : ETH_ZLEN;
        unsigned char *buf = skb->data;

        /* If some error occurs while trying to transmit this
         * packet, you should return '1' from this function.
         * In such a case you _may not_ do anything to the
         * SKB, it is still owned by the network queueing
         * layer when an error is returned.  This means you
         * may not modify any SKB fields, you may not free
         * the SKB, etc.
         */

#if TX_RING
        /* This is the most common case for modern hardware.
         * The spinlock protects this code from the TX complete
         * hardware interrupt handler.  Queue flow control is
         * thus managed under this lock as well.
         */
        unsigned long flags;
        spin_lock_irqsave(&np->lock, flags);

        add_to_tx_ring(np, skb, length);
        dev->trans_start = jiffies;

        /* If we just used up the very last entry in the
         * TX ring on this device, tell the queueing
         * layer to send no more.
         */
        if (tx_full(dev))
                netif_stop_queue(dev);

        /* When the TX completion hw interrupt arrives, this
         * is when the transmit statistics are updated.
         */

        spin_unlock_irqrestore(&np->lock, flags);
#else
        /* This is the case for older hardware which takes
         * a single transmit buffer at a time, and it is
         * just written to the device via PIO.
         *
         * No spin locking is needed since there is no TX complete
         * event.  If by chance your card does have a TX complete
         * hardware IRQ then you may need to utilize np->lock here.
         */
        hardware_send_packet(ioaddr, buf, length);
        np->stats.tx_bytes += skb->len;

        dev->trans_start = jiffies;

        /* You might need to clean up and record Tx statistics here. */
        if (inw(ioaddr) == /*RU*/81)
                np->stats.tx_aborted_errors++;
        dev_kfree_skb (skb);
#endif

        return NETDEV_TX_OK;
}

#if TX_RING
/* This handles TX complete events posted by the device
 * via interrupts.
 */
void net_tx(struct net_device *dev)
{
        struct net_local *np = netdev_priv(dev);
        int entry;

        /* This protects us from concurrent execution of
         * our dev->hard_start_xmit function above.
         */
        spin_lock(&np->lock);

        entry = np->tx_old;
        while (tx_entry_is_sent(np, entry)) {
                struct sk_buff *skb = np->skbs[entry];

                np->stats.tx_bytes += skb->len;
                dev_kfree_skb_irq (skb);

                entry = next_tx_entry(np, entry);
        }
        np->tx_old = entry;

        /* If we had stopped the queue due to a "tx full"
         * condition, and space has now been made available,
         * wake up the queue.
         */
        if (netif_queue_stopped(dev) && ! tx_full(dev))
                netif_wake_queue(dev);

        spin_unlock(&np->lock);
}
#endif

/*
 * The typical workload of the driver:
 * Handle the network interface interrupts.
 */
static irqreturn_t net_interrupt(int irq, void *dev_id)
{
        struct net_device *dev = dev_id;
        struct net_local *np;
        int ioaddr, status;
        int handled = 0;

        ioaddr = dev->base_addr;

        np = netdev_priv(dev);
        status = inw(ioaddr + 0);

        if (status == 0)
                goto out;
        handled = 1;

        if (status & RX_INTR) {
                /* Got a packet(s). */
                net_rx(dev);
        }
#if TX_RING
        if (status & TX_INTR) {
                /* Transmit complete. */
                net_tx(dev);
                np->stats.tx_packets++;
                netif_wake_queue(dev);
        }
#endif
        if (status & COUNTERS_INTR) {
                /* Increment the appropriate 'localstats' field. */
                np->stats.tx_window_errors++;
        }
out:
        return IRQ_RETVAL(handled);
}

/* We have a good packet(s), get it/them out of the buffers. */
static void
net_rx(struct net_device *dev)
{
        struct net_local *lp = netdev_priv(dev);
        int ioaddr = dev->base_addr;
        int boguscount = 10;

        do {
                int status = inw(ioaddr);
                int pkt_len = inw(ioaddr);

                if (pkt_len == 0)               /* Read all the frames? */
                        break;                  /* Done for now */

                if (status & 0x40) {    /* There was an error. */
                        lp->stats.rx_errors++;
                        if (status & 0x20) lp->stats.rx_frame_errors++;
                        if (status & 0x10) lp->stats.rx_over_errors++;
                        if (status & 0x08) lp->stats.rx_crc_errors++;
                        if (status & 0x04) lp->stats.rx_fifo_errors++;
                } else {
                        /* Malloc up new buffer. */
                        struct sk_buff *skb;

                        lp->stats.rx_bytes+=pkt_len;

                        skb = dev_alloc_skb(pkt_len);
                        if (skb == NULL) {
                                printk(KERN_NOTICE "%s: Memory squeeze, dropping packet.\n",
                                           dev->name);
                                lp->stats.rx_dropped++;
                                break;
                        }
                        skb->dev = dev;

                        /* 'skb->data' points to the start of sk_buff data area. */
                        memcpy(skb_put(skb,pkt_len), (void*)dev->rmem_start,
                                   pkt_len);
                        /* or */
                        insw(ioaddr, skb->data, (pkt_len + 1) >> 1);

                        netif_rx(skb);
                        lp->stats.rx_packets++;
                        lp->stats.rx_bytes += pkt_len;
                }
        } while (--boguscount);

        return;
}

/* The inverse routine to net_open(). */
static int
net_close(struct net_device *dev)
{
        struct net_local *lp = netdev_priv(dev);
        int ioaddr = dev->base_addr;

        lp->open_time = 0;

        netif_stop_queue(dev);

        /* Flush the Tx and disable Rx here. */

        disable_dma(dev->dma);

        /* If not IRQ or DMA jumpered, free up the line. */
        outw(0x00, ioaddr+0);   /* Release the physical interrupt line. */

        free_irq(dev->irq, dev);
        free_dma(dev->dma);

        /* Update the statistics here. */

        return 0;

}

/*
 * Get the current statistics.
 * This may be called with the card open or closed.
 */
static struct net_device_stats *net_get_stats(struct net_device *dev)
{
        struct net_local *lp = netdev_priv(dev);
        short ioaddr = dev->base_addr;

        /* Update the statistics from the device registers. */
        lp->stats.rx_missed_errors = inw(ioaddr+1);
        return &lp->stats;
}

/*
 * Set or clear the multicast filter for this adaptor.
 * num_addrs == -1      Promiscuous mode, receive all packets
 * num_addrs == 0       Normal mode, clear multicast list
 * num_addrs > 0        Multicast mode, receive normal and MC packets,
 *                      and do best-effort filtering.
 */
static void
set_multicast_list(struct net_device *dev)
{
        short ioaddr = dev->base_addr;
        if (dev->flags&IFF_PROMISC)
        {
                /* Enable promiscuous mode */
                outw(MULTICAST|PROMISC, ioaddr);
        }
        else if((dev->flags&IFF_ALLMULTI) || dev->mc_count > HW_MAX_ADDRS)
        {
                /* Disable promiscuous mode, use normal mode. */
                hardware_set_filter(NULL);

                outw(MULTICAST, ioaddr);
        }
        else if(dev->mc_count)
        {
                /* Walk the address list, and load the filter */
                hardware_set_filter(dev->mc_list);

                outw(MULTICAST, ioaddr);
        }
        else
                outw(0, ioaddr);
}

#ifdef MODULE

static struct net_device *this_device;
static int io = 0x300;
static int irq;
static int dma;
static int mem;
MODULE_LICENSE("GPL");

int init_module(void)
{
        struct net_device *dev;
        int result;

        if (io == 0)
                printk(KERN_WARNING "%s: You shouldn't use auto-probing with insmod!\n",
                           cardname);
        dev = alloc_etherdev(sizeof(struct net_local));
        if (!dev)
                return -ENOMEM;

        /* Copy the parameters from insmod into the device structure. */
        dev->base_addr = io;
        dev->irq       = irq;
        dev->dma       = dma;
        dev->mem_start = mem;
        if (do_netcard_probe(dev) == 0) {
                this_device = dev;
                return 0;
        }
        free_netdev(dev);
        return -ENXIO;
}

void
cleanup_module(void)
{
        unregister_netdev(this_device);
        cleanup_card(this_device);
        free_netdev(this_device);
}

#endif /* MODULE */