xref: /netbsd-src/sys/arch/sun2/dev/if_ec.c (revision 7330f729ccf0bd976a06f95fad452fe774fc7fd1)
1 /*	$NetBSD: if_ec.c,v 1.34 2019/05/29 10:07:29 msaitoh 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 1.34 2019/05/29 10:07:29 msaitoh 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 #include <net/if_ether.h>
57 #include <net/if_media.h>
58 #include <net/bpf.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 <machine/cpu.h>
69 #include <machine/autoconf.h>
70 #include <machine/idprom.h>
71 #include <machine/bus.h>
72 #include <machine/intr.h>
73 
74 #include <sun2/dev/if_ecreg.h>
75 
76 /*
77  * Interface softc.
78  */
79 struct ec_softc {
80 	device_t sc_dev;
81 	void *sc_ih;
82 
83 	struct ethercom sc_ethercom;	/* ethernet common */
84 	struct ifmedia sc_media;	/* our supported media */
85 
86 	bus_space_tag_t sc_iot;	/* bus space tag */
87 	bus_space_handle_t sc_ioh;	/* bus space handle */
88 
89 	u_char sc_jammed;	/* nonzero if the net is jammed */
90 	u_char sc_colliding;	/* nonzero if the net is colliding */
91 	uint32_t sc_backoff_seed;	/* seed for the backoff PRNG */
92 
93 	krndsource_t rnd_source;
94 };
95 
96 /* Macros to read and write the CSR. */
97 #define	ECREG_CSR_RD bus_space_read_2(sc->sc_iot, sc->sc_ioh, ECREG_CSR)
98 #define	ECREG_CSR_WR(val) bus_space_write_2(sc->sc_iot, sc->sc_ioh, ECREG_CSR, val)
99 
100 /* After this many collisions, the packet is dropped. */
101 #define	EC_COLLISIONS_JAMMED		16
102 
103 /*
104  * Various constants used in the backoff pseudorandom
105  * number generator.
106  */
107 #define	EC_BACKOFF_PRNG_COLL_MAX	10
108 #define	EC_BACKOFF_PRNG_MUL		1103515245
109 #define	EC_BACKOFF_PRNG_ADD		12345
110 #define	EC_BACKOFF_PRNG_MASK		0x7fffffff
111 
112 /*
113  * Prototypes
114  */
115 int ec_intr(void *);
116 void ec_reset(struct ifnet *);
117 int ec_init(struct ifnet *);
118 int ec_ioctl(struct ifnet *, u_long, void *);
119 void ec_watchdog(struct ifnet *);
120 void ec_start(struct ifnet *);
121 
122 void ec_recv(struct ec_softc *, int);
123 void ec_coll(struct ec_softc *);
124 void ec_copyin(struct ec_softc *, void *, int, size_t);
125 void ec_copyout(struct ec_softc *, const void *, int, size_t);
126 
127 int ec_mediachange(struct ifnet *);
128 void ec_mediastatus(struct ifnet *, struct ifmediareq *);
129 
130 int ec_match(device_t, cfdata_t, void *);
131 void ec_attach(device_t, device_t, void *);
132 
133 CFATTACH_DECL_NEW(ec, sizeof(struct ec_softc),
134     ec_match, ec_attach, NULL, NULL);
135 
136 /*
137  * Copy board memory to kernel.
138  */
139 void
140 ec_copyin(struct ec_softc *sc, void *p, int offset, size_t size)
141 {
142 
143 	bus_space_copyin(sc->sc_iot, sc->sc_ioh, offset, p, size);
144 }
145 
146 /*
147  * Copy from kernel space to board memory.
148  */
149 void
150 ec_copyout(struct ec_softc *sc, const void *p, int offset, size_t size)
151 {
152 
153 	bus_space_copyout(sc->sc_iot, sc->sc_ioh, offset, p, size);
154 }
155 
156 int
157 ec_match(device_t parent, cfdata_t cf, void *aux)
158 {
159 	struct mbmem_attach_args *mbma = aux;
160 	bus_space_handle_t bh;
161 	bool matched;
162 
163 	/* No default Multibus address. */
164 	if (mbma->mbma_paddr == -1)
165 		return 0;
166 
167 	/* Make sure there is something there... */
168 	if (bus_space_map(mbma->mbma_bustag, mbma->mbma_paddr, ECREG_BANK_SZ,
169 	    0, &bh))
170 		return 0;
171 	matched = (bus_space_peek_2(mbma->mbma_bustag, bh, 0, NULL) == 0);
172 	bus_space_unmap(mbma->mbma_bustag, bh, ECREG_BANK_SZ);
173 	if (!matched)
174 		return 0;
175 
176 	/* Default interrupt priority. */
177 	if (mbma->mbma_pri == -1)
178 		mbma->mbma_pri = 3;
179 
180 	return 1;
181 }
182 
183 void
184 ec_attach(device_t parent, device_t self, void *aux)
185 {
186 	struct ec_softc *sc = device_private(self);
187 	struct mbmem_attach_args *mbma = aux;
188 	struct ifnet *ifp = &sc->sc_ethercom.ec_if;
189 	uint8_t myaddr[ETHER_ADDR_LEN];
190 
191 	sc->sc_dev = self;
192 
193 	aprint_normal("\n");
194 
195 	/* Map in the board control regs. */
196 	sc->sc_iot = mbma->mbma_bustag;
197 	if (bus_space_map(mbma->mbma_bustag, mbma->mbma_paddr, ECREG_BANK_SZ,
198 	    0, &sc->sc_ioh))
199 		panic("%s: can't map regs", __func__);
200 
201 	/* Reset the board. */
202 	ECREG_CSR_WR(EC_CSR_RESET);
203 	delay(160);
204 
205 	/*
206 	 * Copy out the board ROM Ethernet address,
207 	 * and use the non-vendor-ID part to seed
208 	 * our backoff pseudorandom number generator.
209 	 */
210 	bus_space_read_region_1(sc->sc_iot, sc->sc_ioh,
211 	    ECREG_AROM, myaddr, ETHER_ADDR_LEN);
212 	sc->sc_backoff_seed =
213 	    (myaddr[3] << 16) | (myaddr[4] << 8) | (myaddr[5]) | 1;
214 
215 	/* Initialize ifnet structure. */
216 	strcpy(ifp->if_xname, device_xname(self));
217 	ifp->if_softc = sc;
218 	ifp->if_start = ec_start;
219 	ifp->if_ioctl = ec_ioctl;
220 	ifp->if_init = ec_init;
221 	ifp->if_watchdog = ec_watchdog;
222 	ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX;
223 	IFQ_SET_READY(&ifp->if_snd);
224 
225         /* Initialize ifmedia structures. */
226 	sc->sc_ethercom.ec_ifmedia = &sc->sc_media;
227 	ifmedia_init(&sc->sc_media, 0, ec_mediachange, ec_mediastatus);
228 	ifmedia_add(&sc->sc_media, IFM_ETHER | IFM_MANUAL, 0, NULL);
229 	ifmedia_set(&sc->sc_media, IFM_ETHER | IFM_MANUAL);
230 
231 	/* Now we can attach the interface. */
232 	if_attach(ifp);
233 	if_deferred_start_init(ifp, NULL);
234 	idprom_etheraddr(myaddr);
235 	ether_ifattach(ifp, myaddr);
236 	aprint_normal_dev(self, "address %s\n", ether_sprintf(myaddr));
237 
238 	bus_intr_establish(mbma->mbma_bustag, mbma->mbma_pri, IPL_NET, 0,
239 	    ec_intr, sc);
240 
241 	rnd_attach_source(&sc->rnd_source, device_xname(self),
242 	    RND_TYPE_NET, RND_FLAG_DEFAULT);
243 }
244 
245 /*
246  * Reset interface.
247  */
248 void
249 ec_reset(struct ifnet *ifp)
250 {
251         int s;
252 
253         s = splnet();
254         ec_init(ifp);
255         splx(s);
256 }
257 
258 
259 /*
260  * Initialize interface.
261  */
262 int
263 ec_init(struct ifnet *ifp)
264 {
265 	struct ec_softc *sc = ifp->if_softc;
266 
267 	/* Reset the board. */
268 	ECREG_CSR_WR(EC_CSR_RESET);
269 	delay(160);
270 
271 	/* Set the Ethernet address. */
272 	bus_space_write_region_1(sc->sc_iot, sc->sc_ioh,
273 	    ECREG_ARAM, CLLADDR(sc->sc_ethercom.ec_if.if_sadl), ETHER_ADDR_LEN);
274 	ECREG_CSR_WR((ECREG_CSR_RD & EC_CSR_INTPA) | EC_CSR_AMSW);
275 	ECREG_CSR_WR(ECREG_CSR_RD & 0);
276 
277 	/* Enable interrupts. */
278 	ECREG_CSR_WR((ECREG_CSR_RD & EC_CSR_INTPA) |
279 	    EC_CSR_BBSW | EC_CSR_ABSW | EC_CSR_BINT | EC_CSR_AINT |
280 	    (ifp->if_flags & IFF_PROMISC ? EC_CSR_PROMISC : EC_CSR_PA));
281 
282 	/* Set flags appropriately. */
283 	ifp->if_flags |= IFF_RUNNING;
284 	ifp->if_flags &= ~IFF_OACTIVE;
285 
286 	/* Start output. */
287 	ec_start(ifp);
288 
289 	return 0;
290 }
291 
292 /*
293  * Start output on interface.
294  */
295 void
296 ec_start(struct ifnet *ifp)
297 {
298 	struct ec_softc *sc = ifp->if_softc;
299 	struct mbuf *m, *m0;
300 	int s;
301 	u_int count, realcount;
302 	bus_size_t off;
303 	static uint8_t padding[ETHER_MIN_LEN - ETHER_CRC_LEN] = {0};
304 
305 	s = splnet();
306 
307 	/* Don't do anything if output is active. */
308 	if ((ifp->if_flags & IFF_OACTIVE) != 0) {
309 		splx(s);
310 		return;
311 	}
312 	/* Don't do anything if the output queue is empty. */
313 	IFQ_DEQUEUE(&ifp->if_snd, m0);
314 	if (m0 == NULL) {
315 		splx(s);
316 		return;
317 	}
318 
319 	/* The BPF tap. */
320 	bpf_mtap(ifp, m0, BPF_D_OUT);
321 
322 	/* Size the packet. */
323 	count = EC_BUF_SZ - m0->m_pkthdr.len;
324 
325 	/* Copy the packet into the xmit buffer. */
326 	realcount = MIN(count, EC_PKT_MAXTDOFF);
327 	bus_space_write_2(sc->sc_iot, sc->sc_ioh, ECREG_TBUF, realcount);
328 	for (off = realcount, m = m0; m != 0; off += m->m_len, m = m->m_next)
329 		ec_copyout(sc, mtod(m, uint8_t *), ECREG_TBUF + off, m->m_len);
330 	m_freem(m0);
331 	if (count - realcount)
332 		ec_copyout(sc, padding, ECREG_TBUF + off, count - realcount);
333 
334 	/* Enable the transmitter. */
335 	ECREG_CSR_WR((ECREG_CSR_RD & EC_CSR_PA) |
336 	    EC_CSR_TBSW | EC_CSR_TINT | EC_CSR_JINT);
337 	ifp->if_flags |= IFF_OACTIVE;
338 
339 	/* Done. */
340 	splx(s);
341 }
342 
343 /*
344  * Controller interrupt.
345  */
346 int
347 ec_intr(void *arg)
348 {
349 	struct ec_softc *sc = arg;
350 	struct ifnet *ifp = &sc->sc_ethercom.ec_if;
351 	int recv_first;
352 	int recv_second;
353 	int retval;
354 
355 	retval = 0;
356 
357 	/* Check for received packet(s). */
358 	recv_first = recv_second = 0;
359 	switch (ECREG_CSR_RD & (EC_CSR_BBSW | EC_CSR_ABSW | EC_CSR_RBBA)) {
360 
361 	case (EC_CSR_BBSW | EC_CSR_ABSW):
362 	case (EC_CSR_BBSW | EC_CSR_ABSW | EC_CSR_RBBA):
363 		/* Neither buffer is full.  Is this a transmit interrupt?
364 		 * Acknowledge the interrupt ourselves. */
365 		ECREG_CSR_WR(ECREG_CSR_RD &
366 		    (EC_CSR_TINT | EC_CSR_JINT | EC_CSR_PAMASK));
367 		ECREG_CSR_WR((ECREG_CSR_RD & EC_CSR_INTPA) |
368 		    EC_CSR_BINT | EC_CSR_AINT);
369 		break;
370 
371 	case EC_CSR_BBSW:
372 	case (EC_CSR_BBSW | EC_CSR_RBBA):
373 		/* Only the A buffer is full. */
374 		recv_first = EC_CSR_AINT;
375 		break;
376 
377 	case EC_CSR_ABSW:
378 	case (EC_CSR_ABSW | EC_CSR_RBBA):
379 		/* Only the B buffer is full. */
380 		recv_first = EC_CSR_BINT;
381 		break;
382 
383 	case 0:
384 		/* Both the A buffer and the B buffer are full, and the A
385 		 * buffer is older than the B buffer. */
386 		recv_first = EC_CSR_AINT;
387 		recv_second = EC_CSR_BINT;
388 		break;
389 
390 	case EC_CSR_RBBA:
391 		/* Both the A buffer and the B buffer are full, and the B
392 		 * buffer is older than the A buffer. */
393 		recv_first = EC_CSR_BINT;
394 		recv_second = EC_CSR_AINT;
395 		break;
396 	}
397 
398 	/* Receive packets. */
399 	if (recv_first) {
400 
401 		/* Acknowledge the interrupt. */
402 		ECREG_CSR_WR(ECREG_CSR_RD &
403 		    ((EC_CSR_BINT | EC_CSR_AINT | EC_CSR_TINT | EC_CSR_JINT |
404 		      EC_CSR_PAMASK) ^ (recv_first | recv_second)));
405 
406 		/* Receive a packet. */
407 		ec_recv(sc, recv_first);
408 
409 		/* Receive a packet. */
410 		if (recv_second)
411 			ec_recv(sc, recv_second);
412 
413 		retval++;
414 	}
415 	/* Check for a transmitted packet. */
416 	if (ifp->if_flags & IFF_OACTIVE) {
417 
418 		/* If we got a collision. */
419 		if (ECREG_CSR_RD & EC_CSR_JAM) {
420 			ECREG_CSR_WR(ECREG_CSR_RD &
421 			    (EC_CSR_BINT | EC_CSR_AINT | EC_CSR_PAMASK));
422 			sc->sc_ethercom.ec_if.if_collisions++;
423 			retval++;
424 			ec_coll(sc);
425 
426 		}
427 		/* If we transmitted a packet. */
428 		else if ((ECREG_CSR_RD & EC_CSR_TBSW) == 0) {
429 			ECREG_CSR_WR(ECREG_CSR_RD &
430 			    (EC_CSR_BINT | EC_CSR_AINT | EC_CSR_PAMASK));
431 			retval++;
432 			sc->sc_ethercom.ec_if.if_opackets++;
433 			sc->sc_jammed = 0;
434 			ifp->if_flags &= ~IFF_OACTIVE;
435 			if_schedule_deferred_start(ifp);
436 		}
437 	} else {
438 
439 		/* Make sure we disable transmitter interrupts. */
440 		ECREG_CSR_WR(ECREG_CSR_RD &
441 		    (EC_CSR_BINT | EC_CSR_AINT | EC_CSR_PAMASK));
442 	}
443 
444 	return retval;
445 }
446 
447 /*
448  * Read in a packet from the board.
449  */
450 void
451 ec_recv(struct ec_softc *sc, int intbit)
452 {
453 	struct ifnet *ifp = &sc->sc_ethercom.ec_if;
454 	struct mbuf *m0, *m, *newm;
455 	bus_size_t buf;
456 	uint16_t status;
457 	uint16_t doff;
458 	int length, total_length;
459 
460 	buf = EC_CSR_INT_BUF(intbit);
461 
462 	/* Read in the packet status. */
463 	status = bus_space_read_2(sc->sc_iot, sc->sc_ioh, buf);
464 	doff = status & EC_PKT_DOFF;
465 
466 	for (total_length = -1, m0 = NULL;;) {
467 
468 		/* Check for an error. */
469 		if (status & (EC_PKT_FCSERR | EC_PKT_RGERR | EC_PKT_FRERR) ||
470 		    doff < EC_PKT_MINRDOFF ||
471 		    doff > EC_PKT_MAXRDOFF) {
472 			printf("%s: garbled packet, status 0x%04x; dropping\n",
473 			    device_xname(sc->sc_dev), (unsigned int)status);
474 			break;
475 		}
476 
477 		/* Adjust for the header. */
478 		total_length = doff - EC_PKT_RDOFF;
479 		buf += EC_PKT_RDOFF;
480 
481 		/* XXX - sometimes the card reports a large data offset. */
482 		if (total_length > (ETHER_MAX_LEN - ETHER_CRC_LEN)) {
483 #ifdef DEBUG
484 			printf("%s: fixing too-large length of %d\n",
485 			    device_xname(sc->sc_dev), total_length);
486 #endif
487 			total_length = (ETHER_MAX_LEN - ETHER_CRC_LEN);
488 		}
489 
490 		MGETHDR(m0, M_DONTWAIT, MT_DATA);
491 		if (m0 == NULL)
492 			break;
493 		m_set_rcvif(m0, ifp);
494 		m0->m_pkthdr.len = total_length;
495 		length = MHLEN;
496 		m = m0;
497 
498 		while (total_length > 0) {
499 			if (total_length >= MINCLSIZE) {
500 				MCLGET(m, M_DONTWAIT);
501 				if ((m->m_flags & M_EXT) == 0)
502 					break;
503 				length = MCLBYTES;
504 			}
505 			m->m_len = length = uimin(total_length, length);
506 			ec_copyin(sc, mtod(m, uint8_t *), buf, length);
507 			total_length -= length;
508 			buf += length;
509 
510 			if (total_length > 0) {
511 				MGET(newm, M_DONTWAIT, MT_DATA);
512 				if (newm == NULL)
513 					break;
514 				length = MLEN;
515 				m = m->m_next = newm;
516 			}
517 		}
518 		break;
519 	}
520 
521 	if (total_length == 0) {
522 		/* Pass the packet up. */
523 		if_percpuq_enqueue(ifp->if_percpuq, m0);
524 
525 	} else {
526 		/* Something went wrong. */
527 		if (m0 != NULL)
528 			m_freem(m0);
529 		ifp->if_ierrors++;
530 	}
531 
532 	/* Give the receive buffer back to the card. */
533 	buf = EC_CSR_INT_BUF(intbit);
534 	bus_space_write_2(sc->sc_iot, sc->sc_ioh, buf, 0);
535 	ECREG_CSR_WR((ECREG_CSR_RD & EC_CSR_INTPA) |
536 	    EC_CSR_INT_BSW(intbit) | intbit);
537 }
538 
539 int
540 ec_mediachange(struct ifnet *ifp)
541 {
542 
543 	return 0;
544 }
545 
546 void
547 ec_mediastatus(struct ifnet *ifp, struct ifmediareq *ifmr)
548 {
549 
550 	if ((ifp->if_flags & IFF_UP) == 0)
551 		return;
552 
553 	ifmr->ifm_status = IFM_AVALID | IFM_ACTIVE;
554 }
555 
556 /*
557  * Process an ioctl request. This code needs some work - it looks pretty ugly.
558  */
559 int
560 ec_ioctl(struct ifnet *ifp, u_long cmd, void *data)
561 {
562 	struct ifaddr *ifa = (struct ifaddr *)data;
563 	int s, error = 0;
564 
565 	s = splnet();
566 
567 	switch (cmd) {
568 
569 	case SIOCINITIFADDR:
570 		ifp->if_flags |= IFF_UP;
571 
572 		switch (ifa->ifa_addr->sa_family) {
573 #ifdef INET
574 		case AF_INET:
575 			ec_init(ifp);
576 			arp_ifinit(ifp, ifa);
577 			break;
578 #endif
579 		default:
580 			ec_init(ifp);
581 			break;
582 		}
583 		break;
584 
585 	case SIOCSIFFLAGS:
586 		if ((error = ifioctl_common(ifp, cmd, data)) != 0)
587 			break;
588 		switch (ifp->if_flags & (IFF_UP | IFF_RUNNING)) {
589 		case IFF_RUNNING:
590 			/*
591 			 * If interface is marked down and it is running, then
592 			 * stop it.
593 			 */
594 			ifp->if_flags &= ~IFF_RUNNING;
595 			break;
596 		case IFF_UP:
597 			/*
598 			 * If interface is marked up and it is stopped, then
599 			 * start it.
600 			 */
601 			ec_init(ifp);
602 			break;
603 		default:
604 			/*
605 			 * Some other important flag might have changed, so
606 			 * reset.
607 			 */
608 			ec_reset(ifp);
609 			break;
610 		}
611 		break;
612 
613 	default:
614 		error = ether_ioctl(ifp, cmd, data);
615 		break;
616 	}
617 
618 	splx(s);
619 	return error;
620 }
621 
622 /*
623  * Collision routine.
624  */
625 void
626 ec_coll(struct ec_softc *sc)
627 {
628 	struct ifnet *ifp = &sc->sc_ethercom.ec_if;
629 	u_short jams;
630 
631 	if ((++sc->sc_colliding) >= EC_COLLISIONS_JAMMED) {
632 		sc->sc_ethercom.ec_if.if_oerrors++;
633 		if (!sc->sc_jammed)
634 			printf("%s: ethernet jammed\n",
635 			    device_xname(sc->sc_dev));
636 		sc->sc_jammed = 1;
637 		sc->sc_colliding = 0;
638 		ifp->if_flags &= ~IFF_OACTIVE;
639 		if_schedule_deferred_start(ifp);
640 	} else {
641 		jams = MAX(sc->sc_colliding, EC_BACKOFF_PRNG_COLL_MAX);
642 		sc->sc_backoff_seed =
643 		    ((sc->sc_backoff_seed * EC_BACKOFF_PRNG_MUL) +
644 		    EC_BACKOFF_PRNG_ADD) & EC_BACKOFF_PRNG_MASK;
645 		bus_space_write_2(sc->sc_iot, sc->sc_ioh, ECREG_BACKOFF,
646 		    -(((sc->sc_backoff_seed >> 8) & ~(-1 << jams)) + 1));
647 		ECREG_CSR_WR((ECREG_CSR_RD & EC_CSR_INTPA) |
648 		    EC_CSR_JAM | EC_CSR_TINT | EC_CSR_JINT);
649 	}
650 }
651 
652 /*
653  * Device timeout routine.
654  */
655 void
656 ec_watchdog(struct ifnet *ifp)
657 {
658 	struct ec_softc *sc = ifp->if_softc;
659 
660 	log(LOG_ERR, "%s: device timeout\n", device_xname(sc->sc_dev));
661 	sc->sc_ethercom.ec_if.if_oerrors++;
662 
663 	ec_reset(ifp);
664 }
665