/* $Id: hysdn_net.c,v 1.8.6.4 2001/09/23 22:24:54 kai Exp $
 *
 * Linux driver for HYSDN cards, net (ethernet type) handling routines.
 *
 * Author    Werner Cornelius (werner@titro.de) for Hypercope GmbH
 * Copyright 1999 by Werner Cornelius (werner@titro.de)
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 *
 * This net module has been inspired by the skeleton driver from
 * Donald Becker (becker@CESDIS.gsfc.nasa.gov)
 *
 */

#include <linux/module.h>
#include <linux/signal.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/inetdevice.h>

#include "hysdn_defs.h"

unsigned int hynet_enable = 0xffffffff;
module_param(hynet_enable, uint, 0);

#define MAX_SKB_BUFFERS 20      /* number of buffers for keeping TX-data */

/****************************************************************************/
/* structure containing the complete network data. The structure is aligned */
/* in a way that both, the device and statistics are kept inside it.        */
/* for proper access, the device structure MUST be the first var/struct     */
/* inside the definition.                                                   */
/****************************************************************************/
struct net_local {
        /* 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.
         */
        struct net_device *dev;
        spinlock_t lock;
        struct sk_buff *skbs[MAX_SKB_BUFFERS];  /* pointers to tx-skbs */
        int in_idx, out_idx;    /* indexes to buffer ring */
        int sk_count;           /* number of buffers currently in ring */
};                              /* net_local */



/*********************************************************************/
/* 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 in_device *in_dev;
        hysdn_card *card = dev->ml_priv;
        int i;

        netif_start_queue(dev); /* start tx-queueing */

        /* Fill in the MAC-level header (if not already set) */
        if (!card->mac_addr[0]) {
                for (i = 0; i < ETH_ALEN; i++)
                        dev->dev_addr[i] = 0xfc;
                if ((in_dev = dev->ip_ptr) != NULL) {
                        const struct in_ifaddr *ifa;

                        rcu_read_lock();
                        ifa = rcu_dereference(in_dev->ifa_list);
                        if (ifa != NULL)
                                memcpy(dev->dev_addr + (ETH_ALEN - sizeof(ifa->ifa_local)), &ifa->ifa_local, sizeof(ifa->ifa_local));
                        rcu_read_unlock();
                }
        } else
                memcpy(dev->dev_addr, card->mac_addr, ETH_ALEN);

        return (0);
}                               /* net_open */

/*******************************************/
/* flush the currently occupied tx-buffers */
/* must only be called when device closed  */
/*******************************************/
static void
flush_tx_buffers(struct net_local *nl)
{

        while (nl->sk_count) {
                dev_kfree_skb(nl->skbs[nl->out_idx++]);         /* free skb */
                if (nl->out_idx >= MAX_SKB_BUFFERS)
                        nl->out_idx = 0;        /* wrap around */
                nl->sk_count--;
        }
}                               /* flush_tx_buffers */


/*********************************************************************/
/* close/decativate the device. The device is not removed, but only  */
/* deactivated.                                                      */
/*********************************************************************/
static int
net_close(struct net_device *dev)
{

        netif_stop_queue(dev);  /* disable queueing */

        flush_tx_buffers((struct net_local *) dev);

        return (0);             /* success */
}                               /* net_close */

/************************************/
/* send a packet on this interface. */
/* new style for kernel >= 2.3.33   */
/************************************/
static netdev_tx_t
net_send_packet(struct sk_buff *skb, struct net_device *dev)
{
        struct net_local *lp = (struct net_local *) dev;

        spin_lock_irq(&lp->lock);

        lp->skbs[lp->in_idx++] = skb;   /* add to buffer list */
        if (lp->in_idx >= MAX_SKB_BUFFERS)
                lp->in_idx = 0; /* wrap around */
        lp->sk_count++;         /* adjust counter */
        netif_trans_update(dev);

        /* 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 (lp->sk_count >= MAX_SKB_BUFFERS)
                netif_stop_queue(dev);

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

        spin_unlock_irq(&lp->lock);

        if (lp->sk_count <= 3) {
                schedule_work(&((hysdn_card *) dev->ml_priv)->irq_queue);
        }
        return NETDEV_TX_OK;    /* success */
}                               /* net_send_packet */



/***********************************************************************/
/* acknowlegde a packet send. The network layer will be informed about */
/* completion                                                          */
/***********************************************************************/
void
hysdn_tx_netack(hysdn_card *card)
{
        struct net_local *lp = card->netif;

        if (!lp)
                return;         /* non existing device */


        if (!lp->sk_count)
                return;         /* error condition */

        lp->dev->stats.tx_packets++;
        lp->dev->stats.tx_bytes += lp->skbs[lp->out_idx]->len;

        dev_kfree_skb(lp->skbs[lp->out_idx++]);         /* free skb */
        if (lp->out_idx >= MAX_SKB_BUFFERS)
                lp->out_idx = 0;        /* wrap around */

        if (lp->sk_count-- == MAX_SKB_BUFFERS)  /* dec usage count */
                netif_start_queue((struct net_device *) lp);
}                               /* hysdn_tx_netack */

/*****************************************************/
/* we got a packet from the network, go and queue it */
/*****************************************************/
void
hysdn_rx_netpkt(hysdn_card *card, unsigned char *buf, unsigned short len)
{
        struct net_local *lp = card->netif;
        struct net_device *dev;
        struct sk_buff *skb;

        if (!lp)
                return;         /* non existing device */

        dev = lp->dev;
        dev->stats.rx_bytes += len;

        skb = dev_alloc_skb(len);
        if (skb == NULL) {
                printk(KERN_NOTICE "%s: Memory squeeze, dropping packet.\n",
                       dev->name);
                dev->stats.rx_dropped++;
                return;
        }
        /* copy the data */
        skb_put_data(skb, buf, len);

        /* determine the used protocol */
        skb->protocol = eth_type_trans(skb, dev);

        dev->stats.rx_packets++;        /* adjust packet count */

        netif_rx(skb);
}                               /* hysdn_rx_netpkt */

/*****************************************************/
/* return the pointer to a network packet to be send */
/*****************************************************/
struct sk_buff *
hysdn_tx_netget(hysdn_card *card)
{
        struct net_local *lp = card->netif;

        if (!lp)
                return (NULL);  /* non existing device */

        if (!lp->sk_count)
                return (NULL);  /* nothing available */

        return (lp->skbs[lp->out_idx]);         /* next packet to send */
}                               /* hysdn_tx_netget */

static const struct net_device_ops hysdn_netdev_ops = {
        .ndo_open               = net_open,
        .ndo_stop               = net_close,
        .ndo_start_xmit         = net_send_packet,
        .ndo_set_mac_address    = eth_mac_addr,
        .ndo_validate_addr      = eth_validate_addr,
};


/*****************************************************************************/
/* hysdn_net_create creates a new net device for the given card. If a device */
/* already exists, it will be deleted and created a new one. The return value */
/* 0 announces success, else a negative error code will be returned.         */
/*****************************************************************************/
int
hysdn_net_create(hysdn_card *card)
{
        struct net_device *dev;
        int i;
        struct net_local *lp;

        if (!card) {
                printk(KERN_WARNING "No card-pt in hysdn_net_create!\n");
                return (-ENOMEM);
        }
        hysdn_net_release(card);        /* release an existing net device */

        dev = alloc_etherdev(sizeof(struct net_local));
        if (!dev) {
                printk(KERN_WARNING "HYSDN: unable to allocate mem\n");
                return (-ENOMEM);
        }

        lp = netdev_priv(dev);
        lp->dev = dev;

        dev->netdev_ops = &hysdn_netdev_ops;
        spin_lock_init(&((struct net_local *) dev)->lock);

        /* initialise necessary or informing fields */
        dev->base_addr = card->iobase;  /* IO address */
        dev->irq = card->irq;   /* irq */

        dev->netdev_ops = &hysdn_netdev_ops;
        if ((i = register_netdev(dev))) {
                printk(KERN_WARNING "HYSDN: unable to create network device\n");
                free_netdev(dev);
                return (i);
        }
        dev->ml_priv = card;    /* remember pointer to own data structure */
        card->netif = dev;      /* setup the local pointer */

        if (card->debug_flags & LOG_NET_INIT)
                hysdn_addlog(card, "network device created");
        return 0;               /* and return success */
}                               /* hysdn_net_create */

/***************************************************************************/
/* hysdn_net_release deletes the net device for the given card. The return */
/* value 0 announces success, else a negative error code will be returned. */
/***************************************************************************/
int
hysdn_net_release(hysdn_card *card)
{
        struct net_device *dev = card->netif;

        if (!dev)
                return (0);     /* non existing */

        card->netif = NULL;     /* clear out pointer */
        net_close(dev);

        flush_tx_buffers((struct net_local *) dev);     /* empty buffers */

        unregister_netdev(dev); /* release the device */
        free_netdev(dev);       /* release the memory allocated */
        if (card->debug_flags & LOG_NET_INIT)
                hysdn_addlog(card, "network device deleted");

        return (0);             /* always successful */
}                               /* hysdn_net_release */

/*****************************************************************************/
/* hysdn_net_getname returns a pointer to the name of the network interface. */
/* if the interface is not existing, a "-" is returned.                      */
/*****************************************************************************/
char *
hysdn_net_getname(hysdn_card *card)
{
        struct net_device *dev = card->netif;

        if (!dev)
                return ("-");   /* non existing */

        return (dev->name);
}                               /* hysdn_net_getname */