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29 * From: @(#)if_loop.c 8.1 (Berkeley) 6/10/93
34 * Discard interface driver for protocol testing and timing.
35 * Mimics an Ethernet device so that VLANs can be attached to it etc.
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 */
47 #include <net/bpf.h> /* bpf(9) */
48 #include <net/ethernet.h> /* Ethernet related constants and types */
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) */
55 static const char edscname[] = "edsc";
58 * Software configuration of an interface specific to this device type.
61 struct ifnet *sc_ifp; /* ptr to generic interface configuration */
64 * A non-null driver can keep various things here, for instance,
65 * the hardware revision, cached values of write-only registers, etc.
70 * Attach to the interface cloning framework.
72 static struct if_clone *edsc_cloner;
73 static int edsc_clone_create(struct if_clone *, int, caddr_t);
74 static void edsc_clone_destroy(struct ifnet *);
77 * Interface driver methods.
79 static void edsc_init(void *dummy);
80 /* static void edsc_input(struct ifnet *ifp, struct mbuf *m); would be here */
81 static int edsc_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data);
82 static void edsc_start(struct ifnet *ifp);
85 * We'll allocate softc instances from this.
87 static MALLOC_DEFINE(M_EDSC, edscname, "Ethernet discard interface");
90 * Create an interface instance.
93 edsc_clone_create(struct if_clone *ifc, int unit, caddr_t params)
95 struct edsc_softc *sc;
97 static u_char eaddr[ETHER_ADDR_LEN]; /* 0:0:0:0:0:0 */
100 * Allocate soft and ifnet structures. Link each to the other.
102 sc = malloc(sizeof(struct edsc_softc), M_EDSC, M_WAITOK | M_ZERO);
103 ifp = sc->sc_ifp = if_alloc(IFT_ETHER);
112 * Get a name for this particular interface in its ifnet structure.
114 if_initname(ifp, edscname, unit);
117 * Typical Ethernet interface flags: we can do broadcast and
118 * multicast but can't hear our own broadcasts or multicasts.
120 ifp->if_flags = IFF_BROADCAST | IFF_MULTICAST | IFF_SIMPLEX;
123 * We can pretent we have the whole set of hardware features
124 * because we just discard all packets we get from the upper layer.
125 * However, the features are disabled initially. They can be
126 * enabled via edsc_ioctl() when needed.
128 ifp->if_capabilities =
129 IFCAP_VLAN_MTU | IFCAP_VLAN_HWTAGGING | IFCAP_VLAN_HWCSUM |
130 IFCAP_HWCSUM | IFCAP_TSO |
132 ifp->if_capenable = 0;
135 * Set the interface driver methods.
137 ifp->if_init = edsc_init;
138 /* ifp->if_input = edsc_input; */
139 ifp->if_ioctl = edsc_ioctl;
140 ifp->if_start = edsc_start;
143 * Set the maximum output queue length from the global parameter.
145 ifp->if_snd.ifq_maxlen = ifqmaxlen;
148 * Do ifnet initializations common to all Ethernet drivers
149 * and attach to the network interface framework.
150 * TODO: Pick a non-zero link level address.
152 ether_ifattach(ifp, eaddr);
155 * Now we can mark the interface as running, i.e., ready
158 ifp->if_drv_flags |= IFF_DRV_RUNNING;
164 * Destroy an interface instance.
167 edsc_clone_destroy(struct ifnet *ifp)
169 struct edsc_softc *sc = ifp->if_softc;
172 * Detach from the network interface framework.
177 * Free memory occupied by ifnet and softc.
184 * This method is invoked from ether_ioctl() when it's time
185 * to bring up the hardware.
188 edsc_init(void *dummy)
190 #if 0 /* what a hardware driver would do here... */
191 struct edsc_soft *sc = (struct edsc_softc *)dummy;
192 struct ifnet *ifp = sc->sc_ifp;
199 * Network interfaces are controlled via the ioctl(2) syscall.
202 edsc_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
204 struct ifreq *ifr = (struct ifreq *)data;
210 * Just turn on any capabilities requested.
211 * The generic ifioctl() function has already made sure
212 * that they are supported, i.e., set in if_capabilities.
214 ifp->if_capenable = ifr->ifr_reqcap;
217 * A h/w driver would need to analyze the requested
218 * bits and program the hardware, e.g.:
220 mask = ifp->if_capenable ^ ifr->ifr_reqcap;
222 if (mask & IFCAP_VLAN_HWTAGGING) {
223 ifp->if_capenable ^= IFCAP_VLAN_HWTAGGING;
225 if (ifp->if_capenable & IFCAP_VLAN_HWTAGGING)
235 * Offload the rest onto the common Ethernet handler.
237 return (ether_ioctl(ifp, cmd, data));
244 * Process the output queue.
247 edsc_start(struct ifnet *ifp)
252 * A hardware interface driver can set IFF_DRV_OACTIVE
253 * in ifp->if_drv_flags:
255 * ifp->if_drv_flags |= IFF_DRV_OACTIVE;
257 * to prevent if_start from being invoked again while the
258 * transmission is under way. The flag is to protect the
259 * device's transmitter, not the method itself. The output
260 * queue is locked and several threads can process it in
261 * parallel safely, so the driver can use other means to
262 * serialize access to the transmitter.
264 * If using IFF_DRV_OACTIVE, the driver should clear the flag
265 * not earlier than the current transmission is complete, e.g.,
266 * upon an interrupt from the device, not just before returning
267 * from if_start. This method merely starts the transmission,
268 * which may proceed asynchronously.
272 * We loop getting packets from the queue until it's empty.
273 * A h/w driver would loop until the device can accept more
274 * data into its buffer, or while there are free transmit
275 * descriptors, or whatever.
279 * Try to dequeue one packet. Stop if the queue is empty.
280 * Use IF_DEQUEUE() here if ALTQ(9) support is unneeded.
282 IFQ_DEQUEUE(&ifp->if_snd, m);
287 * Let bpf(9) at the packet.
292 * Update the interface counters.
294 ifp->if_obytes += m->m_pkthdr.len;
298 * Finally, just drop the packet.
299 * TODO: Reply to ARP requests unless IFF_NOARP is set.
305 * ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
306 * would be here only if the transmission were synchronous.
311 * This function provides handlers for module events, namely load and unload.
314 edsc_modevent(module_t mod, int type, void *data)
320 * Connect to the network interface cloning framework.
321 * The last argument is the number of units to be created
322 * from the outset. It's also the minimum number of units
323 * allowed. We don't want any units created as soon as the
326 edsc_cloner = if_clone_simple(edscname, edsc_clone_create,
327 edsc_clone_destroy, 0);
332 * Disconnect from the cloning framework.
333 * Existing interfaces will be disposed of properly.
335 if_clone_detach(edsc_cloner);
340 * There are other event types, but we don't handle them.
348 static moduledata_t edsc_mod = {
349 "if_edsc", /* name */
350 edsc_modevent, /* event handler */
351 NULL /* additional data */
354 DECLARE_MODULE(if_edsc, edsc_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);