FreeBSD/Linux Kernel Cross Reference
sys/net/if_edsc.c

     /*-
      * Copyright (c) 1982, 1986, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following edsclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following edsclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE EDSCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      From: @(#)if_loop.c     8.1 (Berkeley) 6/10/93
     * $FreeBSD: releng/10.2/sys/net/if_edsc.c 241610 2012-10-16 13:37:54Z glebius $
     */
    
    /*
     * Discard interface driver for protocol testing and timing.
     * Mimics an Ethernet device so that VLANs can be attached to it etc.
     */
    
    #include <sys/param.h>          /* types, important constants */
    #include <sys/kernel.h>         /* SYSINIT for load-time initializations */
    #include <sys/malloc.h>         /* malloc(9) */
    #include <sys/module.h>         /* module(9) */
    #include <sys/mbuf.h>           /* mbuf(9) */
    #include <sys/socket.h>         /* struct ifreq */
    #include <sys/sockio.h>         /* socket ioctl's */
    /* #include <sys/systm.h> if you need printf(9) or other all-purpose globals */
    
    #include <net/bpf.h>            /* bpf(9) */
    #include <net/ethernet.h>       /* Ethernet related constants and types */
    #include <net/if.h>             /* basic part of ifnet(9) */
    #include <net/if_clone.h>       /* network interface cloning */
    #include <net/if_types.h>       /* IFT_ETHER and friends */
    #include <net/if_var.h>         /* kernel-only part of ifnet(9) */
    
    static const char edscname[] = "edsc";
    
    /*
     * Software configuration of an interface specific to this device type.
     */
    struct edsc_softc {
            struct ifnet    *sc_ifp; /* ptr to generic interface configuration */
    
            /*
             * A non-null driver can keep various things here, for instance,
             * the hardware revision, cached values of write-only registers, etc.
             */
    };
    
    /*
     * Attach to the interface cloning framework.
     */
    static struct if_clone *edsc_cloner;
    static int      edsc_clone_create(struct if_clone *, int, caddr_t);
    static void     edsc_clone_destroy(struct ifnet *);
    
    /*
     * Interface driver methods.
     */
    static void     edsc_init(void *dummy);
    /* static void edsc_input(struct ifnet *ifp, struct mbuf *m); would be here */
    static int      edsc_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data);
    static void     edsc_start(struct ifnet *ifp);
    
    /*
     * We'll allocate softc instances from this.
     */
    static          MALLOC_DEFINE(M_EDSC, edscname, "Ethernet discard interface");
    
    /*
     * Create an interface instance.
     */
    static int
    edsc_clone_create(struct if_clone *ifc, int unit, caddr_t params)
    {
            struct edsc_softc       *sc;
            struct ifnet            *ifp;
            static u_char            eaddr[ETHER_ADDR_LEN]; /* 0:0:0:0:0:0 */
    
            /*
             * Allocate soft and ifnet structures.  Link each to the other.
            */
           sc = malloc(sizeof(struct edsc_softc), M_EDSC, M_WAITOK | M_ZERO);
           ifp = sc->sc_ifp = if_alloc(IFT_ETHER);
           if (ifp == NULL) {
                   free(sc, M_EDSC);
                   return (ENOSPC);
           }
   
           ifp->if_softc = sc;
   
           /*
            * Get a name for this particular interface in its ifnet structure.
            */
           if_initname(ifp, edscname, unit);
   
           /*
            * Typical Ethernet interface flags: we can do broadcast and
            * multicast but can't hear our own broadcasts or multicasts.
            */
           ifp->if_flags = IFF_BROADCAST | IFF_MULTICAST | IFF_SIMPLEX;
   
           /*
            * We can pretent we have the whole set of hardware features
            * because we just discard all packets we get from the upper layer.
            * However, the features are disabled initially.  They can be
            * enabled via edsc_ioctl() when needed.
            */
           ifp->if_capabilities =
               IFCAP_VLAN_MTU | IFCAP_VLAN_HWTAGGING | IFCAP_VLAN_HWCSUM |
               IFCAP_HWCSUM | IFCAP_TSO |
               IFCAP_JUMBO_MTU;
           ifp->if_capenable = 0;
   
           /*
            * Set the interface driver methods.
            */
           ifp->if_init = edsc_init;
           /* ifp->if_input = edsc_input; */
           ifp->if_ioctl = edsc_ioctl;
           ifp->if_start = edsc_start;
   
           /*
            * Set the maximum output queue length from the global parameter.
            */
           ifp->if_snd.ifq_maxlen = ifqmaxlen;
   
           /*
            * Do ifnet initializations common to all Ethernet drivers
            * and attach to the network interface framework.
            * TODO: Pick a non-zero link level address.
            */
           ether_ifattach(ifp, eaddr);
   
           /*
            * Now we can mark the interface as running, i.e., ready
            * for operation.
            */
           ifp->if_drv_flags |= IFF_DRV_RUNNING;
   
           return (0);
   }
   
   /*
    * Destroy an interface instance.
    */
   static void
   edsc_clone_destroy(struct ifnet *ifp)
   {
           struct edsc_softc       *sc = ifp->if_softc;
   
           /*
            * Detach from the network interface framework.
            */
           ether_ifdetach(ifp);
   
           /*
            * Free memory occupied by ifnet and softc.
            */
           if_free(ifp);
           free(sc, M_EDSC);
   }
   
   /*
    * This method is invoked from ether_ioctl() when it's time
    * to bring up the hardware.
    */
   static void
   edsc_init(void *dummy)
   {
   #if 0   /* what a hardware driver would do here... */
           struct edsc_soft        *sc = (struct edsc_softc *)dummy;
           struct ifnet            *ifp = sc->sc_ifp;
   
           /* blah-blah-blah */
   #endif
   }
   
   /*
    * Network interfaces are controlled via the ioctl(2) syscall.
    */
   static int
   edsc_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
   {
           struct ifreq            *ifr = (struct ifreq *)data;
   
           switch (cmd) {
           case SIOCSIFCAP:
   #if 1
                   /*
                    * Just turn on any capabilities requested.
                    * The generic ifioctl() function has already made sure
                    * that they are supported, i.e., set in if_capabilities.
                    */
                   ifp->if_capenable = ifr->ifr_reqcap;
   #else
                   /*
                    * A h/w driver would need to analyze the requested
                    * bits and program the hardware, e.g.:
                    */
                   mask = ifp->if_capenable ^ ifr->ifr_reqcap;
   
                   if (mask & IFCAP_VLAN_HWTAGGING) {
                           ifp->if_capenable ^= IFCAP_VLAN_HWTAGGING;
   
                           if (ifp->if_capenable & IFCAP_VLAN_HWTAGGING)
                                   /* blah-blah-blah */
                           else
                                   /* etc-etc-etc */
                   }
   #endif
                   break;
   
           default:
                   /*
                    * Offload the rest onto the common Ethernet handler.
                    */
                   return (ether_ioctl(ifp, cmd, data));
           }
   
           return (0);
   }
   
   /*
    * Process the output queue.
    */
   static void
   edsc_start(struct ifnet *ifp)
   {
           struct mbuf             *m;
   
           /*
            * A hardware interface driver can set IFF_DRV_OACTIVE
            * in ifp->if_drv_flags:
            *
            * ifp->if_drv_flags |= IFF_DRV_OACTIVE;
            *
            * to prevent if_start from being invoked again while the
            * transmission is under way.  The flag is to protect the
            * device's transmitter, not the method itself.  The output
            * queue is locked and several threads can process it in
            * parallel safely, so the driver can use other means to
            * serialize access to the transmitter.
            *
            * If using IFF_DRV_OACTIVE, the driver should clear the flag
            * not earlier than the current transmission is complete, e.g.,
            * upon an interrupt from the device, not just before returning
            * from if_start.  This method merely starts the transmission,
            * which may proceed asynchronously.
            */
   
           /*
            * We loop getting packets from the queue until it's empty.
            * A h/w driver would loop until the device can accept more
            * data into its buffer, or while there are free transmit
            * descriptors, or whatever.
            */
           for (;;) {
                   /*
                    * Try to dequeue one packet.  Stop if the queue is empty.
                    * Use IF_DEQUEUE() here if ALTQ(9) support is unneeded.
                    */
                   IFQ_DEQUEUE(&ifp->if_snd, m);
                   if (m == NULL)
                           break;
   
                   /*
                    * Let bpf(9) at the packet.
                    */
                   BPF_MTAP(ifp, m);
   
                   /*
                    * Update the interface counters.
                    */
                   ifp->if_obytes += m->m_pkthdr.len;
                   ifp->if_opackets++;
   
                   /*
                    * Finally, just drop the packet.
                    * TODO: Reply to ARP requests unless IFF_NOARP is set.
                    */
                   m_freem(m);
           }
   
           /*
            * ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
            * would be here only if the transmission were synchronous.
            */
   }
   
   /*
    * This function provides handlers for module events, namely load and unload.
    */
   static int
   edsc_modevent(module_t mod, int type, void *data)
   {
   
           switch (type) {
           case MOD_LOAD:
                   /*
                    * Connect to the network interface cloning framework.
                    * The last argument is the number of units to be created
                    * from the outset.  It's also the minimum number of units
                    * allowed.  We don't want any units created as soon as the
                    * driver is loaded.
                    */
                   edsc_cloner = if_clone_simple(edscname, edsc_clone_create,
                       edsc_clone_destroy, 0);
                   break;
   
           case MOD_UNLOAD:
                   /*
                    * Disconnect from the cloning framework.
                    * Existing interfaces will be disposed of properly.
                    */
                   if_clone_detach(edsc_cloner);
                   break;
   
           default:
                   /*
                    * There are other event types, but we don't handle them.
                    * See module(9).
                    */
                   return (EOPNOTSUPP);
           }
           return (0);
   }
   
   static moduledata_t edsc_mod = {
           "if_edsc",                      /* name */
           edsc_modevent,                  /* event handler */
           NULL                            /* additional data */
   };
   
   DECLARE_MODULE(if_edsc, edsc_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);

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