FreeBSD/Linux Kernel Cross Reference
sys/net/if_edsc.c
1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1982, 1986, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following edsclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following edsclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE EDSCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 * From: @(#)if_loop.c 8.1 (Berkeley) 6/10/93
32 * $FreeBSD: releng/12.0/sys/net/if_edsc.c 336676 2018-07-24 16:35:52Z andrew $
33 */
34
35 /*
36 * Discard interface driver for protocol testing and timing.
37 * Mimics an Ethernet device so that VLANs can be attached to it etc.
38 */
39
40 #include <sys/param.h> /* types, important constants */
41 #include <sys/kernel.h> /* SYSINIT for load-time initializations */
42 #include <sys/malloc.h> /* malloc(9) */
43 #include <sys/module.h> /* module(9) */
44 #include <sys/mbuf.h> /* mbuf(9) */
45 #include <sys/socket.h> /* struct ifreq */
46 #include <sys/sockio.h> /* socket ioctl's */
47 /* #include <sys/systm.h> if you need printf(9) or other all-purpose globals */
48
49 #include <net/bpf.h> /* bpf(9) */
50 #include <net/ethernet.h> /* Ethernet related constants and types */
51 #include <net/if.h>
52 #include <net/if_var.h> /* basic part of ifnet(9) */
53 #include <net/if_clone.h> /* network interface cloning */
54 #include <net/if_types.h> /* IFT_ETHER and friends */
55 #include <net/if_var.h> /* kernel-only part of ifnet(9) */
56 #include <net/vnet.h>
57
58 static const char edscname[] = "edsc";
59
60 /*
61 * Software configuration of an interface specific to this device type.
62 */
63 struct edsc_softc {
64 struct ifnet *sc_ifp; /* ptr to generic interface configuration */
65
66 /*
67 * A non-null driver can keep various things here, for instance,
68 * the hardware revision, cached values of write-only registers, etc.
69 */
70 };
71
72 /*
73 * Attach to the interface cloning framework.
74 */
75 VNET_DEFINE_STATIC(struct if_clone *, edsc_cloner);
76 #define V_edsc_cloner VNET(edsc_cloner)
77 static int edsc_clone_create(struct if_clone *, int, caddr_t);
78 static void edsc_clone_destroy(struct ifnet *);
79
80 /*
81 * Interface driver methods.
82 */
83 static void edsc_init(void *dummy);
84 /* static void edsc_input(struct ifnet *ifp, struct mbuf *m); would be here */
85 static int edsc_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data);
86 static void edsc_start(struct ifnet *ifp);
87
88 /*
89 * We'll allocate softc instances from this.
90 */
91 static MALLOC_DEFINE(M_EDSC, edscname, "Ethernet discard interface");
92
93 /*
94 * Create an interface instance.
95 */
96 static int
97 edsc_clone_create(struct if_clone *ifc, int unit, caddr_t params)
98 {
99 struct edsc_softc *sc;
100 struct ifnet *ifp;
101 static u_char eaddr[ETHER_ADDR_LEN]; /* 0:0:0:0:0:0 */
102
103 /*
104 * Allocate soft and ifnet structures. Link each to the other.
105 */
106 sc = malloc(sizeof(struct edsc_softc), M_EDSC, M_WAITOK | M_ZERO);
107 ifp = sc->sc_ifp = if_alloc(IFT_ETHER);
108 if (ifp == NULL) {
109 free(sc, M_EDSC);
110 return (ENOSPC);
111 }
112
113 ifp->if_softc = sc;
114
115 /*
116 * Get a name for this particular interface in its ifnet structure.
117 */
118 if_initname(ifp, edscname, unit);
119
120 /*
121 * Typical Ethernet interface flags: we can do broadcast and
122 * multicast but can't hear our own broadcasts or multicasts.
123 */
124 ifp->if_flags = IFF_BROADCAST | IFF_MULTICAST | IFF_SIMPLEX;
125
126 /*
127 * We can pretent we have the whole set of hardware features
128 * because we just discard all packets we get from the upper layer.
129 * However, the features are disabled initially. They can be
130 * enabled via edsc_ioctl() when needed.
131 */
132 ifp->if_capabilities =
133 IFCAP_VLAN_MTU | IFCAP_VLAN_HWTAGGING | IFCAP_VLAN_HWCSUM |
134 IFCAP_HWCSUM | IFCAP_TSO |
135 IFCAP_JUMBO_MTU;
136 ifp->if_capenable = 0;
137
138 /*
139 * Set the interface driver methods.
140 */
141 ifp->if_init = edsc_init;
142 /* ifp->if_input = edsc_input; */
143 ifp->if_ioctl = edsc_ioctl;
144 ifp->if_start = edsc_start;
145
146 /*
147 * Set the maximum output queue length from the global parameter.
148 */
149 ifp->if_snd.ifq_maxlen = ifqmaxlen;
150
151 /*
152 * Do ifnet initializations common to all Ethernet drivers
153 * and attach to the network interface framework.
154 * TODO: Pick a non-zero link level address.
155 */
156 ether_ifattach(ifp, eaddr);
157
158 /*
159 * Now we can mark the interface as running, i.e., ready
160 * for operation.
161 */
162 ifp->if_drv_flags |= IFF_DRV_RUNNING;
163
164 return (0);
165 }
166
167 /*
168 * Destroy an interface instance.
169 */
170 static void
171 edsc_clone_destroy(struct ifnet *ifp)
172 {
173 struct edsc_softc *sc = ifp->if_softc;
174
175 /*
176 * Detach from the network interface framework.
177 */
178 ether_ifdetach(ifp);
179
180 /*
181 * Free memory occupied by ifnet and softc.
182 */
183 if_free(ifp);
184 free(sc, M_EDSC);
185 }
186
187 /*
188 * This method is invoked from ether_ioctl() when it's time
189 * to bring up the hardware.
190 */
191 static void
192 edsc_init(void *dummy)
193 {
194 #if 0 /* what a hardware driver would do here... */
195 struct edsc_soft *sc = (struct edsc_softc *)dummy;
196 struct ifnet *ifp = sc->sc_ifp;
197
198 /* blah-blah-blah */
199 #endif
200 }
201
202 /*
203 * Network interfaces are controlled via the ioctl(2) syscall.
204 */
205 static int
206 edsc_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
207 {
208 struct ifreq *ifr = (struct ifreq *)data;
209
210 switch (cmd) {
211 case SIOCSIFCAP:
212 #if 1
213 /*
214 * Just turn on any capabilities requested.
215 * The generic ifioctl() function has already made sure
216 * that they are supported, i.e., set in if_capabilities.
217 */
218 ifp->if_capenable = ifr->ifr_reqcap;
219 #else
220 /*
221 * A h/w driver would need to analyze the requested
222 * bits and program the hardware, e.g.:
223 */
224 mask = ifp->if_capenable ^ ifr->ifr_reqcap;
225
226 if (mask & IFCAP_VLAN_HWTAGGING) {
227 ifp->if_capenable ^= IFCAP_VLAN_HWTAGGING;
228
229 if (ifp->if_capenable & IFCAP_VLAN_HWTAGGING)
230 /* blah-blah-blah */
231 else
232 /* etc-etc-etc */
233 }
234 #endif
235 break;
236
237 default:
238 /*
239 * Offload the rest onto the common Ethernet handler.
240 */
241 return (ether_ioctl(ifp, cmd, data));
242 }
243
244 return (0);
245 }
246
247 /*
248 * Process the output queue.
249 */
250 static void
251 edsc_start(struct ifnet *ifp)
252 {
253 struct mbuf *m;
254
255 /*
256 * A hardware interface driver can set IFF_DRV_OACTIVE
257 * in ifp->if_drv_flags:
258 *
259 * ifp->if_drv_flags |= IFF_DRV_OACTIVE;
260 *
261 * to prevent if_start from being invoked again while the
262 * transmission is under way. The flag is to protect the
263 * device's transmitter, not the method itself. The output
264 * queue is locked and several threads can process it in
265 * parallel safely, so the driver can use other means to
266 * serialize access to the transmitter.
267 *
268 * If using IFF_DRV_OACTIVE, the driver should clear the flag
269 * not earlier than the current transmission is complete, e.g.,
270 * upon an interrupt from the device, not just before returning
271 * from if_start. This method merely starts the transmission,
272 * which may proceed asynchronously.
273 */
274
275 /*
276 * We loop getting packets from the queue until it's empty.
277 * A h/w driver would loop until the device can accept more
278 * data into its buffer, or while there are free transmit
279 * descriptors, or whatever.
280 */
281 for (;;) {
282 /*
283 * Try to dequeue one packet. Stop if the queue is empty.
284 * Use IF_DEQUEUE() here if ALTQ(9) support is unneeded.
285 */
286 IFQ_DEQUEUE(&ifp->if_snd, m);
287 if (m == NULL)
288 break;
289
290 /*
291 * Let bpf(9) at the packet.
292 */
293 BPF_MTAP(ifp, m);
294
295 /*
296 * Update the interface counters.
297 */
298 if_inc_counter(ifp, IFCOUNTER_OBYTES, m->m_pkthdr.len);
299 if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
300
301 /*
302 * Finally, just drop the packet.
303 * TODO: Reply to ARP requests unless IFF_NOARP is set.
304 */
305 m_freem(m);
306 }
307
308 /*
309 * ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
310 * would be here only if the transmission were synchronous.
311 */
312 }
313
314 static void
315 vnet_edsc_init(const void *unused __unused)
316 {
317
318 /*
319 * Connect to the network interface cloning framework.
320 * The last argument is the number of units to be created
321 * from the outset. It's also the minimum number of units
322 * allowed. We don't want any units created as soon as the
323 * driver is loaded.
324 */
325 V_edsc_cloner = if_clone_simple(edscname, edsc_clone_create,
326 edsc_clone_destroy, 0);
327 }
328 VNET_SYSINIT(vnet_edsc_init, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY,
329 vnet_edsc_init, NULL);
330
331 static void
332 vnet_edsc_uninit(const void *unused __unused)
333 {
334
335 /*
336 * Disconnect from the cloning framework.
337 * Existing interfaces will be disposed of properly.
338 */
339 if_clone_detach(V_edsc_cloner);
340 }
341 VNET_SYSUNINIT(vnet_edsc_uninit, SI_SUB_INIT_IF, SI_ORDER_ANY,
342 vnet_edsc_uninit, NULL);
343
344 /*
345 * This function provides handlers for module events, namely load and unload.
346 */
347 static int
348 edsc_modevent(module_t mod, int type, void *data)
349 {
350
351 switch (type) {
352 case MOD_LOAD:
353 case MOD_UNLOAD:
354 break;
355 default:
356 /*
357 * There are other event types, but we don't handle them.
358 * See module(9).
359 */
360 return (EOPNOTSUPP);
361 }
362 return (0);
363 }
364
365 static moduledata_t edsc_mod = {
366 "if_edsc", /* name */
367 edsc_modevent, /* event handler */
368 NULL /* additional data */
369 };
370
371 DECLARE_MODULE(if_edsc, edsc_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
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