xref: /netbsd-src/sys/arch/sun2/dev/if_ec.c (revision 946379e7b37692fc43f68eb0d1c10daa0a7f3b6c)
1 /*	$NetBSD: if_ec.c,v 1.23 2015/05/20 09:17:17 ozaki-r Exp $	*/
2 
3 /*
4  * Copyright (c) 2001 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Matthew Fredette.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 /*
33  * 3Com 3C400 device driver
34  */
35 
36 #include <sys/cdefs.h>
37 __KERNEL_RCSID(0, "$NetBSD: if_ec.c,v 1.23 2015/05/20 09:17:17 ozaki-r Exp $");
38 
39 #include "opt_inet.h"
40 #include "opt_ns.h"
41 
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/errno.h>
45 #include <sys/ioctl.h>
46 #include <sys/mbuf.h>
47 #include <sys/socket.h>
48 #include <sys/syslog.h>
49 #include <sys/device.h>
50 #include <sys/endian.h>
51 #include <sys/rndsource.h>
52 
53 #include <net/if.h>
54 #include <net/if_dl.h>
55 #include <net/if_types.h>
56 
57 #include <net/if_ether.h>
58 #include <net/if_media.h>
59 
60 #ifdef INET
61 #include <netinet/in.h>
62 #include <netinet/in_systm.h>
63 #include <netinet/in_var.h>
64 #include <netinet/ip.h>
65 #include <netinet/if_inarp.h>
66 #endif
67 
68 #include <net/bpf.h>
69 #include <net/bpfdesc.h>
70 
71 #include <machine/cpu.h>
72 #include <machine/autoconf.h>
73 #include <machine/idprom.h>
74 #include <machine/bus.h>
75 #include <machine/intr.h>
76 
77 #include <sun2/dev/if_ecreg.h>
78 
79 /*
80  * Interface softc.
81  */
82 struct ec_softc {
83 	device_t sc_dev;
84 	void *sc_ih;
85 
86 	struct ethercom sc_ethercom;	/* ethernet common */
87 	struct ifmedia sc_media;	/* our supported media */
88 
89 	bus_space_tag_t sc_iot;	/* bus space tag */
90 	bus_space_handle_t sc_ioh;	/* bus space handle */
91 
92 	u_char sc_jammed;	/* nonzero if the net is jammed */
93 	u_char sc_colliding;	/* nonzero if the net is colliding */
94 	uint32_t sc_backoff_seed;	/* seed for the backoff PRNG */
95 
96 	krndsource_t rnd_source;
97 };
98 
99 /* Macros to read and write the CSR. */
100 #define	ECREG_CSR_RD bus_space_read_2(sc->sc_iot, sc->sc_ioh, ECREG_CSR)
101 #define	ECREG_CSR_WR(val) bus_space_write_2(sc->sc_iot, sc->sc_ioh, ECREG_CSR, val)
102 
103 /* After this many collisions, the packet is dropped. */
104 #define	EC_COLLISIONS_JAMMED		16
105 
106 /*
107  * Various constants used in the backoff pseudorandom
108  * number generator.
109  */
110 #define	EC_BACKOFF_PRNG_COLL_MAX	10
111 #define	EC_BACKOFF_PRNG_MUL		1103515245
112 #define	EC_BACKOFF_PRNG_ADD		12345
113 #define	EC_BACKOFF_PRNG_MASK		0x7fffffff
114 
115 /*
116  * Prototypes
117  */
118 int ec_intr(void *);
119 void ec_reset(struct ifnet *);
120 int ec_init(struct ifnet *);
121 int ec_ioctl(struct ifnet *, u_long, void *);
122 void ec_watchdog(struct ifnet *);
123 void ec_start(struct ifnet *);
124 
125 void ec_recv(struct ec_softc *, int);
126 void ec_coll(struct ec_softc *);
127 void ec_copyin(struct ec_softc *, void *, int, size_t);
128 void ec_copyout(struct ec_softc *, const void *, int, size_t);
129 
130 int ec_mediachange(struct ifnet *);
131 void ec_mediastatus(struct ifnet *, struct ifmediareq *);
132 
133 int ec_match(device_t, cfdata_t, void *);
134 void ec_attach(device_t, device_t, void *);
135 
136 CFATTACH_DECL_NEW(ec, sizeof(struct ec_softc),
137     ec_match, ec_attach, NULL, NULL);
138 
139 /*
140  * Copy board memory to kernel.
141  */
142 void
143 ec_copyin(struct ec_softc *sc, void *p, int offset, size_t size)
144 {
145 
146 	bus_space_copyin(sc->sc_iot, sc->sc_ioh, offset, p, size);
147 }
148 
149 /*
150  * Copy from kernel space to board memory.
151  */
152 void
153 ec_copyout(struct ec_softc *sc, const void *p, int offset, size_t size)
154 {
155 
156 	bus_space_copyout(sc->sc_iot, sc->sc_ioh, offset, p, size);
157 }
158 
159 int
160 ec_match(device_t parent, cfdata_t cf, void *aux)
161 {
162 	struct mbmem_attach_args *mbma = aux;
163 	bus_space_handle_t bh;
164 	bool matched;
165 
166 	/* No default Multibus address. */
167 	if (mbma->mbma_paddr == -1)
168 		return 0;
169 
170 	/* Make sure there is something there... */
171 	if (bus_space_map(mbma->mbma_bustag, mbma->mbma_paddr, ECREG_BANK_SZ,
172 	    0, &bh))
173 		return 0;
174 	matched = (bus_space_peek_2(mbma->mbma_bustag, bh, 0, NULL) == 0);
175 	bus_space_unmap(mbma->mbma_bustag, bh, ECREG_BANK_SZ);
176 	if (!matched)
177 		return 0;
178 
179 	/* Default interrupt priority. */
180 	if (mbma->mbma_pri == -1)
181 		mbma->mbma_pri = 3;
182 
183 	return 1;
184 }
185 
186 void
187 ec_attach(device_t parent, device_t self, void *aux)
188 {
189 	struct ec_softc *sc = device_private(self);
190 	struct mbmem_attach_args *mbma = aux;
191 	struct ifnet *ifp = &sc->sc_ethercom.ec_if;
192 	uint8_t myaddr[ETHER_ADDR_LEN];
193 
194 	sc->sc_dev = self;
195 
196 	aprint_normal("\n");
197 
198 	/* Map in the board control regs. */
199 	sc->sc_iot = mbma->mbma_bustag;
200 	if (bus_space_map(mbma->mbma_bustag, mbma->mbma_paddr, ECREG_BANK_SZ,
201 	    0, &sc->sc_ioh))
202 		panic("%s: can't map regs", __func__);
203 
204 	/* Reset the board. */
205 	ECREG_CSR_WR(EC_CSR_RESET);
206 	delay(160);
207 
208 	/*
209 	 * Copy out the board ROM Ethernet address,
210 	 * and use the non-vendor-ID part to seed
211 	 * our backoff pseudorandom number generator.
212 	 */
213 	bus_space_read_region_1(sc->sc_iot, sc->sc_ioh,
214 	    ECREG_AROM, myaddr, ETHER_ADDR_LEN);
215 	sc->sc_backoff_seed =
216 	    (myaddr[3] << 16) | (myaddr[4] << 8) | (myaddr[5]) | 1;
217 
218 	/* Initialize ifnet structure. */
219 	strcpy(ifp->if_xname, device_xname(self));
220 	ifp->if_softc = sc;
221 	ifp->if_start = ec_start;
222 	ifp->if_ioctl = ec_ioctl;
223 	ifp->if_init = ec_init;
224 	ifp->if_watchdog = ec_watchdog;
225 	ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_NOTRAILERS;
226 	IFQ_SET_READY(&ifp->if_snd);
227 
228         /* Initialize ifmedia structures. */
229 	ifmedia_init(&sc->sc_media, 0, ec_mediachange, ec_mediastatus);
230 	ifmedia_add(&sc->sc_media, IFM_ETHER|IFM_MANUAL, 0, NULL);
231 	ifmedia_set(&sc->sc_media, IFM_ETHER|IFM_MANUAL);
232 
233 	/* Now we can attach the interface. */
234 	if_attach(ifp);
235 	idprom_etheraddr(myaddr);
236 	ether_ifattach(ifp, myaddr);
237 	aprint_normal_dev(self, "address %s\n", ether_sprintf(myaddr));
238 
239 	bus_intr_establish(mbma->mbma_bustag, mbma->mbma_pri, IPL_NET, 0,
240 	    ec_intr, sc);
241 
242 	rnd_attach_source(&sc->rnd_source, device_xname(self),
243 	    RND_TYPE_NET, RND_FLAG_DEFAULT);
244 }
245 
246 /*
247  * Reset interface.
248  */
249 void
250 ec_reset(struct ifnet *ifp)
251 {
252         int s;
253 
254         s = splnet();
255         ec_init(ifp);
256         splx(s);
257 }
258 
259 
260 /*
261  * Initialize interface.
262  */
263 int
264 ec_init(struct ifnet *ifp)
265 {
266 	struct ec_softc *sc = ifp->if_softc;
267 
268 	/* Reset the board. */
269 	ECREG_CSR_WR(EC_CSR_RESET);
270 	delay(160);
271 
272 	/* Set the Ethernet address. */
273 	bus_space_write_region_1(sc->sc_iot, sc->sc_ioh,
274 	    ECREG_ARAM, CLLADDR(sc->sc_ethercom.ec_if.if_sadl), ETHER_ADDR_LEN);
275 	ECREG_CSR_WR((ECREG_CSR_RD & EC_CSR_INTPA) | EC_CSR_AMSW);
276 	ECREG_CSR_WR(ECREG_CSR_RD & 0);
277 
278 	/* Enable interrupts. */
279 	ECREG_CSR_WR((ECREG_CSR_RD & EC_CSR_INTPA) |
280 	    EC_CSR_BBSW | EC_CSR_ABSW | EC_CSR_BINT | EC_CSR_AINT |
281 	    (ifp->if_flags & IFF_PROMISC ? EC_CSR_PROMISC : EC_CSR_PA));
282 
283 	/* Set flags appropriately. */
284 	ifp->if_flags |= IFF_RUNNING;
285 	ifp->if_flags &= ~IFF_OACTIVE;
286 
287 	/* Start output. */
288 	ec_start(ifp);
289 
290 	return 0;
291 }
292 
293 /*
294  * Start output on interface.
295  */
296 void
297 ec_start(struct ifnet *ifp)
298 {
299 	struct ec_softc *sc = ifp->if_softc;
300 	struct mbuf *m, *m0;
301 	int s;
302 	u_int count, realcount;
303 	bus_size_t off;
304 	static uint8_t padding[ETHER_MIN_LEN - ETHER_CRC_LEN] = {0};
305 
306 	s = splnet();
307 
308 	/* Don't do anything if output is active. */
309 	if ((ifp->if_flags & IFF_OACTIVE) != 0) {
310 		splx(s);
311 		return;
312 	}
313 	/* Don't do anything if the output queue is empty. */
314 	IFQ_DEQUEUE(&ifp->if_snd, m0);
315 	if (m0 == NULL) {
316 		splx(s);
317 		return;
318 	}
319 
320 	/* The BPF tap. */
321 	bpf_mtap(ifp, m0);
322 
323 	/* Size the packet. */
324 	count = EC_BUF_SZ - m0->m_pkthdr.len;
325 
326 	/* Copy the packet into the xmit buffer. */
327 	realcount = MIN(count, EC_PKT_MAXTDOFF);
328 	bus_space_write_2(sc->sc_iot, sc->sc_ioh, ECREG_TBUF, realcount);
329 	for (off = realcount, m = m0; m != 0; off += m->m_len, m = m->m_next)
330 		ec_copyout(sc, mtod(m, uint8_t *), ECREG_TBUF + off, m->m_len);
331 	m_freem(m0);
332 	if (count - realcount)
333 		ec_copyout(sc, padding, ECREG_TBUF + off, count - realcount);
334 
335 	/* Enable the transmitter. */
336 	ECREG_CSR_WR((ECREG_CSR_RD & EC_CSR_PA) |
337 	    EC_CSR_TBSW | EC_CSR_TINT | EC_CSR_JINT);
338 	ifp->if_flags |= IFF_OACTIVE;
339 
340 	/* Done. */
341 	splx(s);
342 }
343 
344 /*
345  * Controller interrupt.
346  */
347 int
348 ec_intr(void *arg)
349 {
350 	struct ec_softc *sc = arg;
351 	struct ifnet *ifp = &sc->sc_ethercom.ec_if;
352 	int recv_first;
353 	int recv_second;
354 	int retval;
355 	struct mbuf *m0;
356 
357 	retval = 0;
358 
359 	/* Check for received packet(s). */
360 	recv_first = recv_second = 0;
361 	switch (ECREG_CSR_RD & (EC_CSR_BBSW | EC_CSR_ABSW | EC_CSR_RBBA)) {
362 
363 	case (EC_CSR_BBSW | EC_CSR_ABSW):
364 	case (EC_CSR_BBSW | EC_CSR_ABSW | EC_CSR_RBBA):
365 		/* Neither buffer is full.  Is this a transmit interrupt?
366 		 * Acknowledge the interrupt ourselves. */
367 		ECREG_CSR_WR(ECREG_CSR_RD &
368 		    (EC_CSR_TINT | EC_CSR_JINT | EC_CSR_PAMASK));
369 		ECREG_CSR_WR((ECREG_CSR_RD & EC_CSR_INTPA) |
370 		    EC_CSR_BINT | EC_CSR_AINT);
371 		break;
372 
373 	case EC_CSR_BBSW:
374 	case (EC_CSR_BBSW | EC_CSR_RBBA):
375 		/* Only the A buffer is full. */
376 		recv_first = EC_CSR_AINT;
377 		break;
378 
379 	case EC_CSR_ABSW:
380 	case (EC_CSR_ABSW | EC_CSR_RBBA):
381 		/* Only the B buffer is full. */
382 		recv_first = EC_CSR_BINT;
383 		break;
384 
385 	case 0:
386 		/* Both the A buffer and the B buffer are full, and the A
387 		 * buffer is older than the B buffer. */
388 		recv_first = EC_CSR_AINT;
389 		recv_second = EC_CSR_BINT;
390 		break;
391 
392 	case EC_CSR_RBBA:
393 		/* Both the A buffer and the B buffer are full, and the B
394 		 * buffer is older than the A buffer. */
395 		recv_first = EC_CSR_BINT;
396 		recv_second = EC_CSR_AINT;
397 		break;
398 	}
399 
400 	/* Receive packets. */
401 	if (recv_first) {
402 
403 		/* Acknowledge the interrupt. */
404 		ECREG_CSR_WR(ECREG_CSR_RD &
405 		    ((EC_CSR_BINT | EC_CSR_AINT | EC_CSR_TINT | EC_CSR_JINT |
406 		      EC_CSR_PAMASK) ^ (recv_first | recv_second)));
407 
408 		/* Receive a packet. */
409 		ec_recv(sc, recv_first);
410 
411 		/* Receive a packet. */
412 		if (recv_second)
413 			ec_recv(sc, recv_second);
414 
415 		retval++;
416 	}
417 	/* Check for a transmitted packet. */
418 	if (ifp->if_flags & IFF_OACTIVE) {
419 
420 		/* If we got a collision. */
421 		if (ECREG_CSR_RD & EC_CSR_JAM) {
422 			ECREG_CSR_WR(ECREG_CSR_RD &
423 			    (EC_CSR_BINT | EC_CSR_AINT | EC_CSR_PAMASK));
424 			sc->sc_ethercom.ec_if.if_collisions++;
425 			retval++;
426 			ec_coll(sc);
427 
428 		}
429 		/* If we transmitted a packet. */
430 		else if ((ECREG_CSR_RD & EC_CSR_TBSW) == 0) {
431 			ECREG_CSR_WR(ECREG_CSR_RD &
432 			    (EC_CSR_BINT | EC_CSR_AINT | EC_CSR_PAMASK));
433 			retval++;
434 			sc->sc_ethercom.ec_if.if_opackets++;
435 			sc->sc_jammed = 0;
436 			ifp->if_flags &= ~IFF_OACTIVE;
437 			IFQ_POLL(&ifp->if_snd, m0);
438 			if (m0 != NULL)
439 				ec_start(ifp);
440 		}
441 	} else {
442 
443 		/* Make sure we disable transmitter interrupts. */
444 		ECREG_CSR_WR(ECREG_CSR_RD &
445 		    (EC_CSR_BINT | EC_CSR_AINT | EC_CSR_PAMASK));
446 	}
447 
448 	return retval;
449 }
450 
451 /*
452  * Read in a packet from the board.
453  */
454 void
455 ec_recv(struct ec_softc *sc, int intbit)
456 {
457 	struct ifnet *ifp = &sc->sc_ethercom.ec_if;
458 	struct mbuf *m0, *m, *newm;
459 	bus_size_t buf;
460 	uint16_t status;
461 	uint16_t doff;
462 	int length, total_length;
463 
464 	buf = EC_CSR_INT_BUF(intbit);
465 
466 	/* Read in the packet status. */
467 	status = bus_space_read_2(sc->sc_iot, sc->sc_ioh, buf);
468 	doff = status & EC_PKT_DOFF;
469 
470 	for (total_length = -1, m0 = NULL;;) {
471 
472 		/* Check for an error. */
473 		if (status & (EC_PKT_FCSERR | EC_PKT_RGERR | EC_PKT_FRERR) ||
474 		    doff < EC_PKT_MINRDOFF ||
475 		    doff > EC_PKT_MAXRDOFF) {
476 			printf("%s: garbled packet, status 0x%04x; dropping\n",
477 			    device_xname(sc->sc_dev), (unsigned int)status);
478 			break;
479 		}
480 
481 		/* Adjust for the header. */
482 		total_length = doff - EC_PKT_RDOFF;
483 		buf += EC_PKT_RDOFF;
484 
485 		/* XXX - sometimes the card reports a large data offset. */
486 		if (total_length > (ETHER_MAX_LEN - ETHER_CRC_LEN)) {
487 #ifdef DEBUG
488 			printf("%s: fixing too-large length of %d\n",
489 			    device_xname(sc->sc_dev), total_length);
490 #endif
491 			total_length = (ETHER_MAX_LEN - ETHER_CRC_LEN);
492 		}
493 
494 		MGETHDR(m0, M_DONTWAIT, MT_DATA);
495 		if (m0 == NULL)
496 			break;
497 		m0->m_pkthdr.rcvif = ifp;
498 		m0->m_pkthdr.len = total_length;
499 		length = MHLEN;
500 		m = m0;
501 
502 		while (total_length > 0) {
503 			if (total_length >= MINCLSIZE) {
504 				MCLGET(m, M_DONTWAIT);
505 				if ((m->m_flags & M_EXT) == 0)
506 					break;
507 				length = MCLBYTES;
508 			}
509 			m->m_len = length = min(total_length, length);
510 			ec_copyin(sc, mtod(m, uint8_t *), buf, length);
511 			total_length -= length;
512 			buf += length;
513 
514 			if (total_length > 0) {
515 				MGET(newm, M_DONTWAIT, MT_DATA);
516 				if (newm == NULL)
517 					break;
518 				length = MLEN;
519 				m = m->m_next = newm;
520 			}
521 		}
522 		break;
523 	}
524 
525 	if (total_length == 0) {
526 		ifp->if_ipackets++;
527 
528 		/*
529 	 	* Check if there's a BPF listener on this interface.
530 	 	* If so, hand off the raw packet to BPF.
531 	 	*/
532 		bpf_mtap(ifp, m0);
533 
534 		/* Pass the packet up. */
535 		(*ifp->if_input)(ifp, m0);
536 
537 	} else {
538 		/* Something went wrong. */
539 		if (m0 != NULL)
540 			m_freem(m0);
541 		ifp->if_ierrors++;
542 	}
543 
544 	/* Give the receive buffer back to the card. */
545 	buf = EC_CSR_INT_BUF(intbit);
546 	bus_space_write_2(sc->sc_iot, sc->sc_ioh, buf, 0);
547 	ECREG_CSR_WR((ECREG_CSR_RD & EC_CSR_INTPA) |
548 	    EC_CSR_INT_BSW(intbit) | intbit);
549 }
550 
551 int
552 ec_mediachange(struct ifnet *ifp)
553 {
554 
555 	return 0;
556 }
557 
558 void
559 ec_mediastatus(struct ifnet *ifp, struct ifmediareq *ifmr)
560 {
561 
562 	if ((ifp->if_flags & IFF_UP) == 0)
563 		return;
564 
565 	ifmr->ifm_status = IFM_AVALID | IFM_ACTIVE;
566 }
567 
568 /*
569  * Process an ioctl request. This code needs some work - it looks pretty ugly.
570  */
571 int
572 ec_ioctl(struct ifnet *ifp, u_long cmd, void *data)
573 {
574 	struct ifaddr *ifa = (struct ifaddr *)data;
575 	struct ifreq *ifr = (struct ifreq *)data;
576 	struct ec_softc *sc = ifp->if_softc;
577 	int s, error = 0;
578 
579 	s = splnet();
580 
581 	switch (cmd) {
582 
583 	case SIOCINITIFADDR:
584 		ifp->if_flags |= IFF_UP;
585 
586 		switch (ifa->ifa_addr->sa_family) {
587 #ifdef INET
588 		case AF_INET:
589 			ec_init(ifp);
590 			arp_ifinit(ifp, ifa);
591 			break;
592 #endif
593 		default:
594 			ec_init(ifp);
595 			break;
596 		}
597 		break;
598 
599 	case SIOCSIFFLAGS:
600 		if ((error = ifioctl_common(ifp, cmd, data)) != 0)
601 			break;
602 		switch (ifp->if_flags & (IFF_UP|IFF_RUNNING)) {
603 		case IFF_RUNNING:
604 			/*
605 			 * If interface is marked down and it is running, then
606 			 * stop it.
607 			 */
608 			ifp->if_flags &= ~IFF_RUNNING;
609 			break;
610 		case IFF_UP:
611 			/*
612 			 * If interface is marked up and it is stopped, then
613 			 * start it.
614 			 */
615 			ec_init(ifp);
616 			break;
617 		default:
618 			/*
619 			 * Some other important flag might have changed, so
620 			 * reset.
621 			 */
622 			ec_reset(ifp);
623 			break;
624 		}
625 		break;
626 
627 	case SIOCGIFMEDIA:
628 	case SIOCSIFMEDIA:
629 		error = ifmedia_ioctl(ifp, ifr, &sc->sc_media, cmd);
630 		break;
631 
632 	default:
633 		error = ether_ioctl(ifp, cmd, data);
634 		break;
635 	}
636 
637 	splx(s);
638 	return error;
639 }
640 
641 /*
642  * Collision routine.
643  */
644 void
645 ec_coll(struct ec_softc *sc)
646 {
647 	struct ifnet *ifp = &sc->sc_ethercom.ec_if;
648 	u_short jams;
649 	struct mbuf *m0;
650 
651 	if ((++sc->sc_colliding) >= EC_COLLISIONS_JAMMED) {
652 		sc->sc_ethercom.ec_if.if_oerrors++;
653 		if (!sc->sc_jammed)
654 			printf("%s: ethernet jammed\n",
655 			    device_xname(sc->sc_dev));
656 		sc->sc_jammed = 1;
657 		sc->sc_colliding = 0;
658 		ifp->if_flags &= ~IFF_OACTIVE;
659 		IFQ_POLL(&ifp->if_snd, m0);
660 		if (m0 != NULL)
661 			ec_start(ifp);
662 	} else {
663 		jams = MAX(sc->sc_colliding, EC_BACKOFF_PRNG_COLL_MAX);
664 		sc->sc_backoff_seed =
665 		    ((sc->sc_backoff_seed * EC_BACKOFF_PRNG_MUL) +
666 		    EC_BACKOFF_PRNG_ADD) & EC_BACKOFF_PRNG_MASK;
667 		bus_space_write_2(sc->sc_iot, sc->sc_ioh, ECREG_BACKOFF,
668 		    -(((sc->sc_backoff_seed >> 8) & ~(-1 << jams)) + 1));
669 		ECREG_CSR_WR((ECREG_CSR_RD & EC_CSR_INTPA) |
670 		    EC_CSR_JAM | EC_CSR_TINT | EC_CSR_JINT);
671 	}
672 }
673 
674 /*
675  * Device timeout routine.
676  */
677 void
678 ec_watchdog(struct ifnet *ifp)
679 {
680 	struct ec_softc *sc = ifp->if_softc;
681 
682 	log(LOG_ERR, "%s: device timeout\n", device_xname(sc->sc_dev));
683 	sc->sc_ethercom.ec_if.if_oerrors++;
684 
685 	ec_reset(ifp);
686 }
687