The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*-
    2  * Copyright (c) 1982, 1986, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following edsclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following edsclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 4. Neither the name of the University nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE EDSCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      From: @(#)if_loop.c     8.1 (Berkeley) 6/10/93
   30  * $FreeBSD: releng/11.1/sys/net/if_edsc.c 302054 2016-06-21 13:48:49Z bz $
   31  */
   32 
   33 /*
   34  * Discard interface driver for protocol testing and timing.
   35  * Mimics an Ethernet device so that VLANs can be attached to it etc.
   36  */
   37 
   38 #include <sys/param.h>          /* types, important constants */
   39 #include <sys/kernel.h>         /* SYSINIT for load-time initializations */
   40 #include <sys/malloc.h>         /* malloc(9) */
   41 #include <sys/module.h>         /* module(9) */
   42 #include <sys/mbuf.h>           /* mbuf(9) */
   43 #include <sys/socket.h>         /* struct ifreq */
   44 #include <sys/sockio.h>         /* socket ioctl's */
   45 /* #include <sys/systm.h> if you need printf(9) or other all-purpose globals */
   46 
   47 #include <net/bpf.h>            /* bpf(9) */
   48 #include <net/ethernet.h>       /* Ethernet related constants and types */
   49 #include <net/if.h>
   50 #include <net/if_var.h>         /* basic part of ifnet(9) */
   51 #include <net/if_clone.h>       /* network interface cloning */
   52 #include <net/if_types.h>       /* IFT_ETHER and friends */
   53 #include <net/if_var.h>         /* kernel-only part of ifnet(9) */
   54 #include <net/vnet.h>
   55 
   56 static const char edscname[] = "edsc";
   57 
   58 /*
   59  * Software configuration of an interface specific to this device type.
   60  */
   61 struct edsc_softc {
   62         struct ifnet    *sc_ifp; /* ptr to generic interface configuration */
   63 
   64         /*
   65          * A non-null driver can keep various things here, for instance,
   66          * the hardware revision, cached values of write-only registers, etc.
   67          */
   68 };
   69 
   70 /*
   71  * Attach to the interface cloning framework.
   72  */
   73 static VNET_DEFINE(struct if_clone *, edsc_cloner);
   74 #define V_edsc_cloner   VNET(edsc_cloner)
   75 static int      edsc_clone_create(struct if_clone *, int, caddr_t);
   76 static void     edsc_clone_destroy(struct ifnet *);
   77 
   78 /*
   79  * Interface driver methods.
   80  */
   81 static void     edsc_init(void *dummy);
   82 /* static void edsc_input(struct ifnet *ifp, struct mbuf *m); would be here */
   83 static int      edsc_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data);
   84 static void     edsc_start(struct ifnet *ifp);
   85 
   86 /*
   87  * We'll allocate softc instances from this.
   88  */
   89 static          MALLOC_DEFINE(M_EDSC, edscname, "Ethernet discard interface");
   90 
   91 /*
   92  * Create an interface instance.
   93  */
   94 static int
   95 edsc_clone_create(struct if_clone *ifc, int unit, caddr_t params)
   96 {
   97         struct edsc_softc       *sc;
   98         struct ifnet            *ifp;
   99         static u_char            eaddr[ETHER_ADDR_LEN]; /* 0:0:0:0:0:0 */
  100 
  101         /*
  102          * Allocate soft and ifnet structures.  Link each to the other.
  103          */
  104         sc = malloc(sizeof(struct edsc_softc), M_EDSC, M_WAITOK | M_ZERO);
  105         ifp = sc->sc_ifp = if_alloc(IFT_ETHER);
  106         if (ifp == NULL) {
  107                 free(sc, M_EDSC);
  108                 return (ENOSPC);
  109         }
  110 
  111         ifp->if_softc = sc;
  112 
  113         /*
  114          * Get a name for this particular interface in its ifnet structure.
  115          */
  116         if_initname(ifp, edscname, unit);
  117 
  118         /*
  119          * Typical Ethernet interface flags: we can do broadcast and
  120          * multicast but can't hear our own broadcasts or multicasts.
  121          */
  122         ifp->if_flags = IFF_BROADCAST | IFF_MULTICAST | IFF_SIMPLEX;
  123 
  124         /*
  125          * We can pretent we have the whole set of hardware features
  126          * because we just discard all packets we get from the upper layer.
  127          * However, the features are disabled initially.  They can be
  128          * enabled via edsc_ioctl() when needed.
  129          */
  130         ifp->if_capabilities =
  131             IFCAP_VLAN_MTU | IFCAP_VLAN_HWTAGGING | IFCAP_VLAN_HWCSUM |
  132             IFCAP_HWCSUM | IFCAP_TSO |
  133             IFCAP_JUMBO_MTU;
  134         ifp->if_capenable = 0;
  135 
  136         /*
  137          * Set the interface driver methods.
  138          */
  139         ifp->if_init = edsc_init;
  140         /* ifp->if_input = edsc_input; */
  141         ifp->if_ioctl = edsc_ioctl;
  142         ifp->if_start = edsc_start;
  143 
  144         /*
  145          * Set the maximum output queue length from the global parameter.
  146          */
  147         ifp->if_snd.ifq_maxlen = ifqmaxlen;
  148 
  149         /*
  150          * Do ifnet initializations common to all Ethernet drivers
  151          * and attach to the network interface framework.
  152          * TODO: Pick a non-zero link level address.
  153          */
  154         ether_ifattach(ifp, eaddr);
  155 
  156         /*
  157          * Now we can mark the interface as running, i.e., ready
  158          * for operation.
  159          */
  160         ifp->if_drv_flags |= IFF_DRV_RUNNING;
  161 
  162         return (0);
  163 }
  164 
  165 /*
  166  * Destroy an interface instance.
  167  */
  168 static void
  169 edsc_clone_destroy(struct ifnet *ifp)
  170 {
  171         struct edsc_softc       *sc = ifp->if_softc;
  172 
  173         /*
  174          * Detach from the network interface framework.
  175          */
  176         ether_ifdetach(ifp);
  177 
  178         /*
  179          * Free memory occupied by ifnet and softc.
  180          */
  181         if_free(ifp);
  182         free(sc, M_EDSC);
  183 }
  184 
  185 /*
  186  * This method is invoked from ether_ioctl() when it's time
  187  * to bring up the hardware.
  188  */
  189 static void
  190 edsc_init(void *dummy)
  191 {
  192 #if 0   /* what a hardware driver would do here... */
  193         struct edsc_soft        *sc = (struct edsc_softc *)dummy;
  194         struct ifnet            *ifp = sc->sc_ifp;
  195 
  196         /* blah-blah-blah */
  197 #endif
  198 }
  199 
  200 /*
  201  * Network interfaces are controlled via the ioctl(2) syscall.
  202  */
  203 static int
  204 edsc_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
  205 {
  206         struct ifreq            *ifr = (struct ifreq *)data;
  207 
  208         switch (cmd) {
  209         case SIOCSIFCAP:
  210 #if 1
  211                 /*
  212                  * Just turn on any capabilities requested.
  213                  * The generic ifioctl() function has already made sure
  214                  * that they are supported, i.e., set in if_capabilities.
  215                  */
  216                 ifp->if_capenable = ifr->ifr_reqcap;
  217 #else
  218                 /*
  219                  * A h/w driver would need to analyze the requested
  220                  * bits and program the hardware, e.g.:
  221                  */
  222                 mask = ifp->if_capenable ^ ifr->ifr_reqcap;
  223 
  224                 if (mask & IFCAP_VLAN_HWTAGGING) {
  225                         ifp->if_capenable ^= IFCAP_VLAN_HWTAGGING;
  226 
  227                         if (ifp->if_capenable & IFCAP_VLAN_HWTAGGING)
  228                                 /* blah-blah-blah */
  229                         else
  230                                 /* etc-etc-etc */
  231                 }
  232 #endif
  233                 break;
  234 
  235         default:
  236                 /*
  237                  * Offload the rest onto the common Ethernet handler.
  238                  */
  239                 return (ether_ioctl(ifp, cmd, data));
  240         }
  241 
  242         return (0);
  243 }
  244 
  245 /*
  246  * Process the output queue.
  247  */
  248 static void
  249 edsc_start(struct ifnet *ifp)
  250 {
  251         struct mbuf             *m;
  252 
  253         /*
  254          * A hardware interface driver can set IFF_DRV_OACTIVE
  255          * in ifp->if_drv_flags:
  256          *
  257          * ifp->if_drv_flags |= IFF_DRV_OACTIVE;
  258          *
  259          * to prevent if_start from being invoked again while the
  260          * transmission is under way.  The flag is to protect the
  261          * device's transmitter, not the method itself.  The output
  262          * queue is locked and several threads can process it in
  263          * parallel safely, so the driver can use other means to
  264          * serialize access to the transmitter.
  265          *
  266          * If using IFF_DRV_OACTIVE, the driver should clear the flag
  267          * not earlier than the current transmission is complete, e.g.,
  268          * upon an interrupt from the device, not just before returning
  269          * from if_start.  This method merely starts the transmission,
  270          * which may proceed asynchronously.
  271          */
  272 
  273         /*
  274          * We loop getting packets from the queue until it's empty.
  275          * A h/w driver would loop until the device can accept more
  276          * data into its buffer, or while there are free transmit
  277          * descriptors, or whatever.
  278          */
  279         for (;;) {
  280                 /*
  281                  * Try to dequeue one packet.  Stop if the queue is empty.
  282                  * Use IF_DEQUEUE() here if ALTQ(9) support is unneeded.
  283                  */
  284                 IFQ_DEQUEUE(&ifp->if_snd, m);
  285                 if (m == NULL)
  286                         break;
  287 
  288                 /*
  289                  * Let bpf(9) at the packet.
  290                  */
  291                 BPF_MTAP(ifp, m);
  292 
  293                 /*
  294                  * Update the interface counters.
  295                  */
  296                 if_inc_counter(ifp, IFCOUNTER_OBYTES, m->m_pkthdr.len);
  297                 if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
  298 
  299                 /*
  300                  * Finally, just drop the packet.
  301                  * TODO: Reply to ARP requests unless IFF_NOARP is set.
  302                  */
  303                 m_freem(m);
  304         }
  305 
  306         /*
  307          * ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
  308          * would be here only if the transmission were synchronous.
  309          */
  310 }
  311 
  312 static void
  313 vnet_edsc_init(const void *unused __unused)
  314 {
  315 
  316         /*
  317          * Connect to the network interface cloning framework.
  318          * The last argument is the number of units to be created
  319          * from the outset.  It's also the minimum number of units
  320          * allowed.  We don't want any units created as soon as the
  321          * driver is loaded.
  322          */
  323         V_edsc_cloner = if_clone_simple(edscname, edsc_clone_create,
  324             edsc_clone_destroy, 0);
  325 }
  326 VNET_SYSINIT(vnet_edsc_init, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY,
  327     vnet_edsc_init, NULL);
  328 
  329 static void
  330 vnet_edsc_uninit(const void *unused __unused)
  331 {
  332 
  333         /*
  334          * Disconnect from the cloning framework.
  335          * Existing interfaces will be disposed of properly.
  336          */
  337         if_clone_detach(V_edsc_cloner);
  338 }
  339 VNET_SYSUNINIT(vnet_edsc_uninit, SI_SUB_INIT_IF, SI_ORDER_ANY,
  340     vnet_edsc_uninit, NULL);
  341 
  342 /*
  343  * This function provides handlers for module events, namely load and unload.
  344  */
  345 static int
  346 edsc_modevent(module_t mod, int type, void *data)
  347 {
  348 
  349         switch (type) {
  350         case MOD_LOAD:
  351         case MOD_UNLOAD:
  352                 break;
  353         default:
  354                 /*
  355                  * There are other event types, but we don't handle them.
  356                  * See module(9).
  357                  */
  358                 return (EOPNOTSUPP);
  359         }
  360         return (0);
  361 }
  362 
  363 static moduledata_t edsc_mod = {
  364         "if_edsc",                      /* name */
  365         edsc_modevent,                  /* event handler */
  366         NULL                            /* additional data */
  367 };
  368 
  369 DECLARE_MODULE(if_edsc, edsc_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);

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