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/*

 * Simulated Ethernet Driver

 *

 * Copyright (C) 1999-2001, 2003 Hewlett-Packard Co

 *      Stephane Eranian <eranian@hpl.hp.com>

 */

#include <linux/config.h>

#include <linux/kernel.h>

#include <linux/sched.h>

#include <linux/types.h>

#include <linux/in.h>

#include <linux/string.h>

#include <linux/init.h>

#include <linux/errno.h>

#include <linux/interrupt.h>

#include <linux/netdevice.h>

#include <linux/etherdevice.h>

#include <linux/inetdevice.h>

#include <linux/if_ether.h>

#include <linux/if_arp.h>

#include <linux/skbuff.h>

#include <linux/notifier.h>

#include <asm/bitops.h>

#include <asm/system.h>

#include <asm/irq.h>

#define SIMETH_RECV_MAX 10

/*

 * Maximum possible received frame for Ethernet.

 * We preallocate an sk_buff of that size to avoid costly

 * memcpy for temporary buffer into sk_buff. We do basically

 * what's done in other drivers, like eepro with a ring.

 * The difference is, of course, that we don't have real DMA !!!

 */

#define SIMETH_FRAME_SIZE       ETH_FRAME_LEN

#define SSC_NETDEV_PROBE                100

#define SSC_NETDEV_SEND                 101

#define SSC_NETDEV_RECV                 102

#define SSC_NETDEV_ATTACH               103

#define SSC_NETDEV_DETACH               104

#define NETWORK_INTR                    8

struct simeth_local {

        struct net_device_stats stats;

        int                     simfd;   /* descriptor in the simulator */

};

static int simeth_probe1(void);

static int simeth_open(struct net_device *dev);

static int simeth_close(struct net_device *dev);

static int simeth_tx(struct sk_buff *skb, struct net_device *dev);

static int simeth_rx(struct net_device *dev);

static struct net_device_stats *simeth_get_stats(struct net_device *dev);

static void simeth_interrupt(int irq, void *dev_id, struct pt_regs * regs);

static void set_multicast_list(struct net_device *dev);

static int simeth_device_event(struct notifier_block *this,unsigned long event, void *ptr);

static char *simeth_version="0.3";

/*

 * This variable is used to establish a mapping between the Linux/ia64 kernel

 * and the host linux kernel.

 *

 * As of today, we support only one card, even though most of the code

 * is ready for many more. The mapping is then:

 *      linux/ia64 -> linux/x86

 *         eth0    -> eth1

 *

 * In the future, we some string operations, we could easily support up

 * to 10 cards (0-9).

 *

 * The default mapping can be changed on the kernel command line by

 * specifying simeth=ethX (or whatever string you want).

 */

static char *simeth_device="eth0";       /* default host interface to use */

static volatile unsigned int card_count; /* how many cards "found" so far */

static int simeth_debug;                /* set to 1 to get debug information */

/*

 * Used to catch IFF_UP & IFF_DOWN events

 */

static struct notifier_block simeth_dev_notifier = {

        simeth_device_event,

};

/*

 * Function used when using a kernel command line option.

 *

 * Format: simeth=interface_name (like eth0)

 */

static int __init

simeth_setup(char *str)

{

        simeth_device = str;

        return 1;

}

__setup("simeth=", simeth_setup);

/*

 * Function used to probe for simeth devices when not installed

 * as a loadable module

 */

int __init

simeth_probe (void)

{

        int r;

        printk(KERN_INFO "simeth: v%s\n", simeth_version);

        r = simeth_probe1();

        if (r == 0) register_netdevice_notifier(&simeth_dev_notifier);

        return r;

}

extern long ia64_ssc (long, long, long, long, int);

extern void ia64_ssc_connect_irq (long intr, long irq);

static inline int

netdev_probe(char *name, unsigned char *ether)

{

        return ia64_ssc(__pa(name), __pa(ether), 0,0, SSC_NETDEV_PROBE);

}

static inline int

netdev_connect(int irq)

{

        /* XXX Fix me

         * this does not support multiple cards

         * also no return value

         */

        ia64_ssc_connect_irq(NETWORK_INTR, irq);

        return 0;

}

static inline int

netdev_attach(int fd, int irq, unsigned int ipaddr)

{

        /* this puts the host interface in the right mode (start interrupting) */

        return ia64_ssc(fd, ipaddr, 0,0, SSC_NETDEV_ATTACH);

}

static inline int

netdev_detach(int fd)

{

        /*

         * inactivate the host interface (don't interrupt anymore) */

        return ia64_ssc(fd, 0,0,0, SSC_NETDEV_DETACH);

}

static inline int

netdev_send(int fd, unsigned char *buf, unsigned int len)

{

        return ia64_ssc(fd, __pa(buf), len, 0, SSC_NETDEV_SEND);

}

static inline int

netdev_read(int fd, unsigned char *buf, unsigned int len)

{

        return ia64_ssc(fd, __pa(buf), len, 0, SSC_NETDEV_RECV);

}

/*

 * Function shared with module code, so cannot be in init section

 *

 * So far this function "detects" only one card (test_&_set) but could

 * be extended easily.

 *

 * Return:

 *      - -ENODEV is no device found

 *      - -ENOMEM is no more memory

 *      - 0 otherwise

 */

static int

simeth_probe1(void)

{

        unsigned char mac_addr[ETH_ALEN];

        struct simeth_local *local;

        struct net_device *dev;

        int fd, i;

        /*

         * XXX Fix me

         * let's support just one card for now

         */

        if (test_and_set_bit(0, &card_count))

                return -ENODEV;

        /*

         * check with the simulator for the device

         */

        fd = netdev_probe(simeth_device, mac_addr);

        if (fd == -1)

                return -ENODEV;

        dev = init_etherdev(NULL, sizeof(struct simeth_local));

        if (!dev)

                return -ENOMEM;

        memcpy(dev->dev_addr, mac_addr, sizeof(mac_addr));

        dev->irq = ia64_alloc_vector();

        /*

         * attach the interrupt in the simulator, this does enable interrupts

         * until a netdev_attach() is called

         */

        netdev_connect(dev->irq);

        memset(dev->priv, 0, sizeof(struct simeth_local));

        local = dev->priv;

        local->simfd = fd; /* keep track of underlying file descriptor */

        dev->open               = simeth_open;

        dev->stop               = simeth_close;

        dev->hard_start_xmit    = simeth_tx;

        dev->get_stats          = simeth_get_stats;

        dev->set_multicast_list = set_multicast_list; /* no yet used */

        /* Fill in the fields of the device structure with ethernet-generic values. */

        ether_setup(dev);

        printk(KERN_INFO "%s: hosteth=%s simfd=%d, HwAddr",

               dev->name, simeth_device, local->simfd);

        for(i = 0; i < ETH_ALEN; i++) {

                printk(" %2.2x", dev->dev_addr[i]);

        }

        printk(", IRQ %d\n", dev->irq);

        return 0;

}

/*

 * actually binds the device to an interrupt vector

 */

static int

simeth_open(struct net_device *dev)

{

        if (request_irq(dev->irq, simeth_interrupt, 0, "simeth", dev)) {

                printk(KERN_WARNING "simeth: unable to get IRQ %d.\n", dev->irq);

                return -EAGAIN;

        }

        netif_start_queue(dev);

        return 0;

}

/* copied from lapbether.c */

static __inline__ int dev_is_ethdev(struct net_device *dev)

{

       return ( dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5));

}

/*

 * Handler for IFF_UP or IFF_DOWN

 *

 * The reason for that is that we don't want to be interrupted when the

 * interface is down. There is no way to unconnect in the simualtor. Instead

 * we use this function to shutdown packet processing in the frame filter

 * in the simulator. Thus no interrupts are generated

 *

 *

 * That's also the place where we pass the IP address of this device to the

 * simulator so that that we can start filtering packets for it

 *

 * There may be a better way of doing this, but I don't know which yet.

 */

static int

simeth_device_event(struct notifier_block *this,unsigned long event, void *ptr)

{

        struct net_device *dev = (struct net_device *)ptr;

        struct simeth_local *local;

        struct in_device *in_dev;

        struct in_ifaddr **ifap = NULL;

        struct in_ifaddr *ifa = NULL;

        int r;

        if ( ! dev ) {

                printk(KERN_WARNING "simeth_device_event dev=0\n");

                return NOTIFY_DONE;

        }

        if ( event != NETDEV_UP && event != NETDEV_DOWN ) return NOTIFY_DONE;

        /*

         * Check whether or not it's for an ethernet device

         *

         * XXX Fixme: This works only as long as we support one

         * type of ethernet device.

         */

        if ( !dev_is_ethdev(dev) ) return NOTIFY_DONE;

        if ((in_dev=dev->ip_ptr) != NULL) {

                for (ifap=&in_dev->ifa_list; (ifa=*ifap) != NULL; ifap=&ifa->ifa_next)

                        if (strcmp(dev->name, ifa->ifa_label) == 0) break;

        }

        if ( ifa == NULL ) {

                printk(KERN_ERR "simeth_open: can't find device %s's ifa\n", dev->name);

                return NOTIFY_DONE;

        }

        printk(KERN_INFO "simeth_device_event: %s ipaddr=0x%x\n",

               dev->name, htonl(ifa->ifa_local));

        /*

         * XXX Fix me

         * if the device was up, and we're simply reconfiguring it, not sure

         * we get DOWN then UP.

         */

        local = dev->priv;

        /* now do it for real */

        r = event == NETDEV_UP ?

                netdev_attach(local->simfd, dev->irq, htonl(ifa->ifa_local)):

                netdev_detach(local->simfd);

        printk(KERN_INFO "simeth: netdev_attach/detach: event=%s ->%d\n",

               event == NETDEV_UP ? "attach":"detach", r);

        return NOTIFY_DONE;

}

static int

simeth_close(struct net_device *dev)

{

        netif_stop_queue(dev);

        free_irq(dev->irq, dev);

        return 0;

}

/*

 * Only used for debug

 */

static void

frame_print(unsigned char *from, unsigned char *frame, int len)

{

        int i;

        printk("%s: (%d) %02x", from, len, frame[0] & 0xff);

        for(i=1; i < 6; i++ ) {

                printk(":%02x", frame[i] &0xff);

        }

        printk(" %2x", frame[6] &0xff);

        for(i=7; i < 12; i++ ) {

                printk(":%02x", frame[i] &0xff);

        }

        printk(" [%02x%02x]\n", frame[12], frame[13]);

        for(i=14; i < len; i++ ) {

                printk("%02x ", frame[i] &0xff);

                if ( (i%10)==0) printk("\n");

        }

        printk("\n");

}

/*

 * Function used to transmit of frame, very last one on the path before

 * going to the simulator.

 */

static int

simeth_tx(struct sk_buff *skb, struct net_device *dev)

{

        struct simeth_local *local = (struct simeth_local *)dev->priv;

#if 0

        /* ensure we have at least ETH_ZLEN bytes (min frame size) */

        unsigned int length = ETH_ZLEN < skb->len ? skb->len : ETH_ZLEN;

        /* Where do the extra padding bytes comes from inthe skbuff ? */

#else

        /* the real driver in the host system is going to take care of that

         * or maybe it's the NIC itself.

         */

        unsigned int length = skb->len;

#endif

        local->stats.tx_bytes += skb->len;

        local->stats.tx_packets++;

        if (simeth_debug > 5) frame_print("simeth_tx", skb->data, length);

        netdev_send(local->simfd, skb->data, length);

        /*

         * we are synchronous on write, so we don't simulate a

         * trasnmit complete interrupt, thus we don't need to arm a tx

         */

        dev_kfree_skb(skb);

        return 0;

}

static inline struct sk_buff *

make_new_skb(struct net_device *dev)

{

        struct sk_buff *nskb;

        /*

         * The +2 is used to make sure that the IP header is nicely

         * aligned (on 4byte boundary I assume 14+2=16)

         */

        nskb = dev_alloc_skb(SIMETH_FRAME_SIZE + 2);

        if ( nskb == NULL ) {

                printk(KERN_NOTICE "%s: memory squeeze. dropping packet.\n", dev->name);

                return NULL;

        }

        nskb->dev = dev;

        skb_reserve(nskb, 2);   /* Align IP on 16 byte boundaries */

        skb_put(nskb,SIMETH_FRAME_SIZE);

        return nskb;

}

/*

 * called from interrupt handler to process a received frame

 */

static int

simeth_rx(struct net_device *dev)

{

        struct simeth_local     *local;

        struct sk_buff          *skb;

        int                     len;

        int                     rcv_count = SIMETH_RECV_MAX;

        local = (struct simeth_local *)dev->priv;

        /*

         * the loop concept has been borrowed from other drivers

         * looks to me like it's a throttling thing to avoid pushing to many

         * packets at one time into the stack. Making sure we can process them

         * upstream and make forward progress overall

         */

        do {

                if ( (skb=make_new_skb(dev)) == NULL ) {

                        printk(KERN_NOTICE "%s: memory squeeze. dropping packet.\n", dev->name);

                        local->stats.rx_dropped++;

                        return 0;

                }

                /*

                 * Read only one frame at a time

                 */

                len = netdev_read(local->simfd, skb->data, SIMETH_FRAME_SIZE);

                if ( len == 0 ) {

                        if ( simeth_debug > 0 ) printk(KERN_WARNING "%s: count=%d netdev_read=0\n",

                                                       dev->name, SIMETH_RECV_MAX-rcv_count);

                        break;

                }

#if 0

                /*

                 * XXX Fix me

                 * Should really do a csum+copy here

                 */

                memcpy(skb->data, frame, len);

#endif

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

                if ( simeth_debug > 6 ) frame_print("simeth_rx", skb->data, len);

                /*

                 * push the packet up & trigger software interrupt

                 */

                netif_rx(skb);

                local->stats.rx_packets++;

                local->stats.rx_bytes += len;

        } while ( --rcv_count );

        return len; /* 0 = nothing left to read, otherwise, we can try again */

}

/*

 * Interrupt handler (Yes, we can do it too !!!)

 */

static void

simeth_interrupt(int irq, void *dev_id, struct pt_regs * regs)

{

        struct net_device *dev = dev_id;

        if ( dev == NULL ) {

                printk(KERN_WARNING "simeth: irq %d for unknown device\n", irq);

                return;

        }

        /*

         * very simple loop because we get interrupts only when receiving

         */

        while (simeth_rx(dev));

}

static struct net_device_stats *

simeth_get_stats(struct net_device *dev)

{

        struct simeth_local  *local = (struct simeth_local *) dev->priv;

        return &local->stats;

}

/* fake multicast ability */

static void

set_multicast_list(struct net_device *dev)

{

        printk(KERN_WARNING "%s: set_multicast_list called\n", dev->name);

}

#ifdef CONFIG_NET_FASTROUTE

static int

simeth_accept_fastpath(struct net_device *dev, struct dst_entry *dst)

{

        printk(KERN_WARNING "%s: simeth_accept_fastpath called\n", dev->name);

        return -1;

}

#endif

__initcall(simeth_probe);