xref: /dragonfly/sys/dev/netif/plip/if_plip.c (revision 017817f0)
1 /*-
2  * Copyright (c) 1997 Poul-Henning Kamp
3  * 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 disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  *
26  *	From Id: lpt.c,v 1.55.2.1 1996/11/12 09:08:38 phk Exp
27  * $FreeBSD: src/sys/dev/ppbus/if_plip.c,v 1.19.2.1 2000/05/24 00:20:57 n_hibma Exp $
28  */
29 
30 /*
31  * Parallel port TCP/IP interfaces added.  I looked at the driver from
32  * MACH but this is a complete rewrite, and btw. incompatible, and it
33  * should perform better too.  I have never run the MACH driver though.
34  *
35  * This driver sends two bytes (0x08, 0x00) in front of each packet,
36  * to allow us to distinguish another format later.
37  *
38  * Now added an Linux/Crynwr compatibility mode which is enabled using
39  * IF_LINK0 - Tim Wilkinson.
40  *
41  * TODO:
42  *    Make HDLC/PPP mode, use IF_LLC1 to enable.
43  *
44  * Connect the two computers using a Laplink parallel cable to use this
45  * feature:
46  *
47  *      +----------------------------------------+
48  * 	|A-name	A-End	B-End	Descr.	Port/Bit |
49  *      +----------------------------------------+
50  *	|DATA0	2	15	Data	0/0x01   |
51  *	|-ERROR	15	2	   	1/0x08   |
52  *      +----------------------------------------+
53  *	|DATA1	3	13	Data	0/0x02	 |
54  *	|+SLCT	13	3	   	1/0x10   |
55  *      +----------------------------------------+
56  *	|DATA2	4	12	Data	0/0x04   |
57  *	|+PE	12	4	   	1/0x20   |
58  *      +----------------------------------------+
59  *	|DATA3	5	10	Strobe	0/0x08   |
60  *	|-ACK	10	5	   	1/0x40   |
61  *      +----------------------------------------+
62  *	|DATA4	6	11	Data	0/0x10   |
63  *	|BUSY	11	6	   	1/~0x80  |
64  *      +----------------------------------------+
65  *	|GND	18-25	18-25	GND	-        |
66  *      +----------------------------------------+
67  *
68  * Expect transfer-rates up to 75 kbyte/sec.
69  *
70  * If GCC could correctly grok
71  *	register int port asm("edx")
72  * the code would be cleaner
73  *
74  * Poul-Henning Kamp <phk@freebsd.org>
75  */
76 
77 /*
78  * Update for ppbus, PLIP support only - Nicolas Souchu
79  */
80 
81 #include "opt_plip.h"
82 
83 #include <sys/param.h>
84 #include <sys/systm.h>
85 #include <sys/module.h>
86 #include <sys/bus.h>
87 #include <sys/mbuf.h>
88 #include <sys/socket.h>
89 #include <sys/sockio.h>
90 #include <sys/kernel.h>
91 #include <sys/malloc.h>
92 #include <sys/rman.h>
93 #include <sys/thread2.h>
94 
95 #include <machine/clock.h>
96 
97 #include <net/if.h>
98 #include <net/ifq_var.h>
99 #include <net/if_types.h>
100 #include <net/netisr.h>
101 
102 #include <netinet/in.h>
103 #include <netinet/in_var.h>
104 
105 #include <net/bpf.h>
106 
107 #include <bus/ppbus/ppbconf.h>
108 #include "ppbus_if.h"
109 #include <bus/ppbus/ppbio.h>
110 
111 #ifndef LPMTU			/* MTU for the lp# interfaces */
112 #define	LPMTU	1500
113 #endif
114 
115 #ifndef LPMAXSPIN1		/* DELAY factor for the lp# interfaces */
116 #define	LPMAXSPIN1	8000   /* Spinning for remote intr to happen */
117 #endif
118 
119 #ifndef LPMAXSPIN2		/* DELAY factor for the lp# interfaces */
120 #define	LPMAXSPIN2	500	/* Spinning for remote handshake to happen */
121 #endif
122 
123 #ifndef LPMAXERRS		/* Max errors before !RUNNING */
124 #define	LPMAXERRS	100
125 #endif
126 
127 #define CLPIPHDRLEN	14	/* We send dummy ethernet addresses (two) + packet type in front of packet */
128 #define	CLPIP_SHAKE	0x80	/* This bit toggles between nibble reception */
129 #define MLPIPHDRLEN	CLPIPHDRLEN
130 
131 #define LPIPHDRLEN	2	/* We send 0x08, 0x00 in front of packet */
132 #define	LPIP_SHAKE	0x40	/* This bit toggles between nibble reception */
133 #if !defined(MLPIPHDRLEN) || LPIPHDRLEN > MLPIPHDRLEN
134 #define MLPIPHDRLEN	LPIPHDRLEN
135 #endif
136 
137 #define	LPIPTBLSIZE	256	/* Size of octet translation table */
138 
139 #define lprintf		if (lptflag) kprintf
140 
141 #ifdef PLIP_DEBUG
142 static int volatile lptflag = 1;
143 #else
144 static int volatile lptflag = 0;
145 #endif
146 
147 struct lp_data {
148 	unsigned short lp_unit;
149 
150 	struct  ifnet	sc_if;
151 	u_char		*sc_ifbuf;
152 	int		sc_iferrs;
153 
154 	struct resource *res_irq;
155 };
156 
157 /* Tables for the lp# interface */
158 static u_char *txmith;
159 #define txmitl (txmith+(1*LPIPTBLSIZE))
160 #define trecvh (txmith+(2*LPIPTBLSIZE))
161 #define trecvl (txmith+(3*LPIPTBLSIZE))
162 
163 static u_char *ctxmith;
164 #define ctxmitl (ctxmith+(1*LPIPTBLSIZE))
165 #define ctrecvh (ctxmith+(2*LPIPTBLSIZE))
166 #define ctrecvl (ctxmith+(3*LPIPTBLSIZE))
167 
168 /* Functions for the lp# interface */
169 static int lpinittables(void);
170 static int lpioctl(struct ifnet *, u_long, caddr_t, struct ucred *);
171 static int lpoutput(struct ifnet *, struct mbuf *, struct sockaddr *,
172 	struct rtentry *);
173 static void lp_intr(void *);
174 
175 #define DEVTOSOFTC(dev) \
176 	((struct lp_data *)device_get_softc(dev))
177 #define UNITOSOFTC(unit) \
178 	((struct lp_data *)devclass_get_softc(lp_devclass, (unit)))
179 #define UNITODEVICE(unit) \
180 	(devclass_get_device(lp_devclass, (unit)))
181 
182 static devclass_t lp_devclass;
183 
184 /*
185  * lpprobe()
186  */
187 static int
188 lp_probe(device_t dev)
189 {
190 	device_t ppbus = device_get_parent(dev);
191 	struct lp_data *lp;
192 	int zero = 0;
193 	uintptr_t irq;
194 
195 	lp = DEVTOSOFTC(dev);
196 
197 	/* retrieve the ppbus irq */
198 	BUS_READ_IVAR(ppbus, dev, PPBUS_IVAR_IRQ, &irq);
199 
200 	/* if we haven't interrupts, the probe fails */
201 	if (irq == -1) {
202 		device_printf(dev, "not an interrupt driven port, failed.\n");
203 		return (ENXIO);
204 	}
205 
206 	/* reserve the interrupt resource, expecting irq is available to continue */
207 	lp->res_irq = bus_alloc_legacy_irq_resource(dev, &zero, irq,
208 	    RF_SHAREABLE);
209 	if (lp->res_irq == NULL) {
210 		device_printf(dev, "cannot reserve interrupt, failed.\n");
211 		return (ENXIO);
212 	}
213 
214 	/*
215 	 * lp dependent initialisation.
216 	 */
217 	lp->lp_unit = device_get_unit(dev);
218 
219 	device_set_desc(dev, "PLIP network interface");
220 
221 	return (0);
222 }
223 
224 static int
225 lp_attach (device_t dev)
226 {
227 	struct lp_data *lp = DEVTOSOFTC(dev);
228 	struct ifnet *ifp = &lp->sc_if;
229 
230 	ifp->if_softc = lp;
231 	if_initname(ifp, "lp", device_get_unit(dev));
232 	ifp->if_mtu = LPMTU;
233 	ifp->if_flags = IFF_SIMPLEX | IFF_POINTOPOINT | IFF_MULTICAST;
234 	ifp->if_ioctl = lpioctl;
235 	ifp->if_output = lpoutput;
236 	ifp->if_type = IFT_PARA;
237 	ifp->if_hdrlen = 0;
238 	ifp->if_addrlen = 0;
239 	ifq_set_maxlen(&ifp->if_snd, IFQ_MAXLEN);
240 	if_attach(ifp, NULL);
241 
242 	bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
243 
244 	return (0);
245 }
246 /*
247  * Build the translation tables for the LPIP (BSD unix) protocol.
248  * We don't want to calculate these nasties in our tight loop, so we
249  * precalculate them when we initialize.
250  */
251 static int
252 lpinittables (void)
253 {
254     int i;
255 
256     if (!txmith)
257 	txmith = kmalloc(4*LPIPTBLSIZE, M_DEVBUF, M_WAITOK);
258 
259     if (!ctxmith)
260 	ctxmith = kmalloc(4*LPIPTBLSIZE, M_DEVBUF, M_WAITOK);
261 
262     for (i=0; i < LPIPTBLSIZE; i++) {
263 	ctxmith[i] = (i & 0xF0) >> 4;
264 	ctxmitl[i] = 0x10 | (i & 0x0F);
265 	ctrecvh[i] = (i & 0x78) << 1;
266 	ctrecvl[i] = (i & 0x78) >> 3;
267     }
268 
269     for (i=0; i < LPIPTBLSIZE; i++) {
270 	txmith[i] = ((i & 0x80) >> 3) | ((i & 0x70) >> 4) | 0x08;
271 	txmitl[i] = ((i & 0x08) << 1) | (i & 0x07);
272 	trecvh[i] = ((~i) & 0x80) | ((i & 0x38) << 1);
273 	trecvl[i] = (((~i) & 0x80) >> 4) | ((i & 0x38) >> 3);
274     }
275 
276     return 0;
277 }
278 
279 /*
280  * Process an ioctl request.
281  */
282 
283 static int
284 lpioctl (struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
285 {
286     device_t dev = UNITODEVICE(ifp->if_dunit);
287     device_t ppbus = device_get_parent(dev);
288     struct lp_data *sc = DEVTOSOFTC(dev);
289     struct ifaddr *ifa = (struct ifaddr *)data;
290     struct ifreq *ifr = (struct ifreq *)data;
291     u_char *ptr;
292     void *ih;
293     int error;
294 
295     switch (cmd) {
296 
297     case SIOCSIFDSTADDR:
298     case SIOCAIFADDR:
299     case SIOCSIFADDR:
300 	if (ifa->ifa_addr->sa_family != AF_INET)
301 	    return EAFNOSUPPORT;
302 
303 	ifp->if_flags |= IFF_UP;
304 	/* FALLTHROUGH */
305     case SIOCSIFFLAGS:
306 	if ((!(ifp->if_flags & IFF_UP)) && (ifp->if_flags & IFF_RUNNING)) {
307 
308 	    ppb_wctr(ppbus, 0x00);
309 	    ifp->if_flags &= ~IFF_RUNNING;
310 
311 	    /* IFF_UP is not set, try to release the bus anyway */
312 	    ppb_release_bus(ppbus, dev);
313 	    break;
314 	}
315 	if (((ifp->if_flags & IFF_UP)) && (!(ifp->if_flags & IFF_RUNNING))) {
316 
317 	    /* XXX
318 	     * Should the request be interruptible?
319 	     */
320 	    if ((error = ppb_request_bus(ppbus, dev, PPB_WAIT|PPB_INTR)))
321 		return (error);
322 
323 	    /* Now IFF_UP means that we own the bus */
324 
325 	    ppb_set_mode(ppbus, PPB_COMPATIBLE);
326 
327 	    if (lpinittables()) {
328 		ppb_release_bus(ppbus, dev);
329 		return ENOBUFS;
330 	    }
331 
332 	    sc->sc_ifbuf = kmalloc(sc->sc_if.if_mtu + MLPIPHDRLEN,
333 				  M_DEVBUF, M_WAITOK);
334 
335 	    /* attach our interrupt handler, later detached when the bus is released */
336 	    error = BUS_SETUP_INTR(ppbus, dev, sc->res_irq, 0,
337 				   lp_intr, dev, &ih, NULL, NULL);
338 	    if (error) {
339 		ppb_release_bus(ppbus, dev);
340 		return (error);
341 	    }
342 
343 	    ppb_wctr(ppbus, IRQENABLE);
344 	    ifp->if_flags |= IFF_RUNNING;
345 	}
346 	break;
347 
348     case SIOCSIFMTU:
349 	ptr = sc->sc_ifbuf;
350 	sc->sc_ifbuf = kmalloc(ifr->ifr_mtu+MLPIPHDRLEN, M_DEVBUF, M_WAITOK);
351 	if (ptr)
352 	    kfree(ptr,M_DEVBUF);
353 	sc->sc_if.if_mtu = ifr->ifr_mtu;
354 	break;
355 
356     case SIOCGIFMTU:
357 	ifr->ifr_mtu = sc->sc_if.if_mtu;
358 	break;
359 
360     case SIOCADDMULTI:
361     case SIOCDELMULTI:
362 	if (ifr == NULL) {
363 	    return EAFNOSUPPORT;		/* XXX */
364 	}
365 	switch (ifr->ifr_addr.sa_family) {
366 
367 	case AF_INET:
368 	    break;
369 
370 	default:
371 	    return EAFNOSUPPORT;
372 	}
373 	break;
374 
375     case SIOCGIFMEDIA:
376 	/*
377 	 * No ifmedia support at this stage; maybe use it
378 	 * in future for eg. protocol selection.
379 	 */
380 	return EINVAL;
381 
382     default:
383 	lprintf("LP:ioctl(0x%lx)\n", cmd);
384 	return EINVAL;
385     }
386     return 0;
387 }
388 
389 static __inline int
390 clpoutbyte (u_char byte, int spin, device_t ppbus)
391 {
392 	ppb_wdtr(ppbus, ctxmitl[byte]);
393 	while (ppb_rstr(ppbus) & CLPIP_SHAKE)
394 		if (--spin == 0) {
395 			return 1;
396 		}
397 	ppb_wdtr(ppbus, ctxmith[byte]);
398 	while (!(ppb_rstr(ppbus) & CLPIP_SHAKE))
399 		if (--spin == 0) {
400 			return 1;
401 		}
402 	return 0;
403 }
404 
405 static __inline int
406 clpinbyte (int spin, device_t ppbus)
407 {
408 	u_char c, cl;
409 
410 	while((ppb_rstr(ppbus) & CLPIP_SHAKE))
411 	    if(!--spin) {
412 		return -1;
413 	    }
414 	cl = ppb_rstr(ppbus);
415 	ppb_wdtr(ppbus, 0x10);
416 
417 	while(!(ppb_rstr(ppbus) & CLPIP_SHAKE))
418 	    if(!--spin) {
419 		return -1;
420 	    }
421 	c = ppb_rstr(ppbus);
422 	ppb_wdtr(ppbus, 0x00);
423 
424 	return (ctrecvl[cl] | ctrecvh[c]);
425 }
426 
427 static void
428 lptap(struct ifnet *ifp, struct mbuf *m)
429 {
430 	/*
431 	 * We need to prepend the address family as a four byte field.
432 	 */
433 	static const uint32_t af = AF_INET;
434 
435 	if (ifp->if_bpf) {
436 		bpf_gettoken();
437 		if (ifp->if_bpf)
438 			bpf_ptap(ifp->if_bpf, m, &af, sizeof(af));
439 		bpf_reltoken();
440 	}
441 }
442 
443 static void
444 lp_intr (void *arg)
445 {
446 	device_t dev = (device_t)arg;
447 	device_t ppbus = device_get_parent(dev);
448 	struct lp_data *sc = DEVTOSOFTC(dev);
449 	int len, j;
450 	u_char *bp;
451 	u_char c, cl;
452 	struct mbuf *top;
453 
454 	crit_enter();
455 
456 	if (sc->sc_if.if_flags & IFF_LINK0) {
457 
458 	    /* Ack. the request */
459 	    ppb_wdtr(ppbus, 0x01);
460 
461 	    /* Get the packet length */
462 	    j = clpinbyte(LPMAXSPIN2, ppbus);
463 	    if (j == -1)
464 		goto err;
465 	    len = j;
466 	    j = clpinbyte(LPMAXSPIN2, ppbus);
467 	    if (j == -1)
468 		goto err;
469 	    len = len + (j << 8);
470 	    if (len > sc->sc_if.if_mtu + MLPIPHDRLEN)
471 		goto err;
472 
473 	    bp  = sc->sc_ifbuf;
474 
475 	    while (len--) {
476 	        j = clpinbyte(LPMAXSPIN2, ppbus);
477 	        if (j == -1) {
478 		    goto err;
479 	        }
480 	        *bp++ = j;
481 	    }
482 	    /* Get and ignore checksum */
483 	    j = clpinbyte(LPMAXSPIN2, ppbus);
484 	    if (j == -1) {
485 	        goto err;
486 	    }
487 
488 	    len = bp - sc->sc_ifbuf;
489 	    if (len <= CLPIPHDRLEN)
490 	        goto err;
491 
492 	    sc->sc_iferrs = 0;
493 
494 	    len -= CLPIPHDRLEN;
495 	    IFNET_STAT_INC(&sc->sc_if, ipackets, 1);
496 	    IFNET_STAT_INC(&sc->sc_if, ibytes, len);
497 	    top = m_devget(sc->sc_ifbuf + CLPIPHDRLEN, len, 0, &sc->sc_if);
498 	    if (top) {
499 		if (sc->sc_if.if_bpf)
500 		    lptap(&sc->sc_if, top);
501 		netisr_queue(NETISR_IP, top);
502 	    }
503 	    goto done;
504 	}
505 	while ((ppb_rstr(ppbus) & LPIP_SHAKE)) {
506 	    len = sc->sc_if.if_mtu + LPIPHDRLEN;
507 	    bp  = sc->sc_ifbuf;
508 	    while (len--) {
509 
510 		cl = ppb_rstr(ppbus);
511 		ppb_wdtr(ppbus, 8);
512 
513 		j = LPMAXSPIN2;
514 		while((ppb_rstr(ppbus) & LPIP_SHAKE))
515 		    if(!--j) goto err;
516 
517 		c = ppb_rstr(ppbus);
518 		ppb_wdtr(ppbus, 0);
519 
520 		*bp++= trecvh[cl] | trecvl[c];
521 
522 		j = LPMAXSPIN2;
523 		while (!((cl=ppb_rstr(ppbus)) & LPIP_SHAKE)) {
524 		    if (cl != c &&
525 			(((cl = ppb_rstr(ppbus)) ^ 0xb8) & 0xf8) ==
526 			  (c & 0xf8))
527 			goto end;
528 		    if (!--j) goto err;
529 		}
530 	    }
531 
532 	end:
533 	    len = bp - sc->sc_ifbuf;
534 	    if (len <= LPIPHDRLEN)
535 		goto err;
536 
537 	    sc->sc_iferrs = 0;
538 
539 	    len -= LPIPHDRLEN;
540 	    IFNET_STAT_INC(&sc->sc_if, ipackets, 1);
541 	    IFNET_STAT_INC(&sc->sc_if, ibytes, len);
542 	    top = m_devget(sc->sc_ifbuf + LPIPHDRLEN, len, 0, &sc->sc_if);
543 	    if (top) {
544 		if (sc->sc_if.if_bpf)
545 		    lptap(&sc->sc_if, top);
546 		netisr_queue(NETISR_IP, top);
547 	    }
548 	}
549 	goto done;
550 
551     err:
552 	ppb_wdtr(ppbus, 0);
553 	lprintf("R");
554 	IFNET_STAT_INC(&sc->sc_if, ierrors, 1);
555 	sc->sc_iferrs++;
556 
557 	/*
558 	 * We are not able to send receive anything for now,
559 	 * so stop wasting our time
560 	 */
561 	if (sc->sc_iferrs > LPMAXERRS) {
562 	    kprintf("lp%d: Too many errors, Going off-line.\n", device_get_unit(dev));
563 	    ppb_wctr(ppbus, 0x00);
564 	    sc->sc_if.if_flags &= ~IFF_RUNNING;
565 	    sc->sc_iferrs=0;
566 	}
567 
568     done:
569 	crit_exit();
570 	return;
571 }
572 
573 static __inline int
574 lpoutbyte (u_char byte, int spin, device_t ppbus)
575 {
576     ppb_wdtr(ppbus, txmith[byte]);
577     while (!(ppb_rstr(ppbus) & LPIP_SHAKE))
578 	if (--spin == 0)
579 		return 1;
580     ppb_wdtr(ppbus, txmitl[byte]);
581     while (ppb_rstr(ppbus) & LPIP_SHAKE)
582 	if (--spin == 0)
583 		return 1;
584     return 0;
585 }
586 
587 static int
588 lpoutput (struct ifnet *ifp, struct mbuf *m,
589 	  struct sockaddr *dst, struct rtentry *rt)
590 {
591     device_t dev = UNITODEVICE(ifp->if_dunit);
592     device_t ppbus = device_get_parent(dev);
593     int err;
594     struct mbuf *mm;
595     u_char *cp = "\0\0";
596     u_char chksum = 0;
597     int count = 0;
598     int i, len, spin;
599 
600     /* We need a sensible value if we abort */
601     cp++;
602     ifp->if_flags |= IFF_RUNNING;
603 
604     err = 1;			/* assume we're aborting because of an error */
605 
606     crit_enter();
607 
608     /* Suspend (on laptops) or receive-errors might have taken us offline */
609     ppb_wctr(ppbus, IRQENABLE);
610 
611     if (ifp->if_flags & IFF_LINK0) {
612 
613 	if (!(ppb_rstr(ppbus) & CLPIP_SHAKE)) {
614 	    lprintf("&");
615 	    lp_intr(dev);
616 	}
617 
618 	/* Alert other end to pending packet */
619 	spin = LPMAXSPIN1;
620 	ppb_wdtr(ppbus, 0x08);
621 	while ((ppb_rstr(ppbus) & 0x08) == 0)
622 		if (--spin == 0) {
623 			goto nend;
624 		}
625 
626 	/* Calculate length of packet, then send that */
627 
628 	count += 14;		/* Ethernet header len */
629 
630 	mm = m;
631 	for (mm = m; mm; mm = mm->m_next) {
632 		count += mm->m_len;
633 	}
634 	if (clpoutbyte(count & 0xFF, LPMAXSPIN1, ppbus))
635 		goto nend;
636 	if (clpoutbyte((count >> 8) & 0xFF, LPMAXSPIN1, ppbus))
637 		goto nend;
638 
639 	/* Send dummy ethernet header */
640 	for (i = 0; i < 12; i++) {
641 		if (clpoutbyte(i, LPMAXSPIN1, ppbus))
642 			goto nend;
643 		chksum += i;
644 	}
645 
646 	if (clpoutbyte(0x08, LPMAXSPIN1, ppbus))
647 		goto nend;
648 	if (clpoutbyte(0x00, LPMAXSPIN1, ppbus))
649 		goto nend;
650 	chksum += 0x08 + 0x00;		/* Add into checksum */
651 
652 	mm = m;
653 	do {
654 		cp = mtod(mm, u_char *);
655 		len = mm->m_len;
656 		while (len--) {
657 			chksum += *cp;
658 			if (clpoutbyte(*cp++, LPMAXSPIN2, ppbus))
659 				goto nend;
660 		}
661 	} while ((mm = mm->m_next));
662 
663 	/* Send checksum */
664 	if (clpoutbyte(chksum, LPMAXSPIN2, ppbus))
665 		goto nend;
666 
667 	/* Go quiescent */
668 	ppb_wdtr(ppbus, 0);
669 
670 	err = 0;			/* No errors */
671 
672 	nend:
673 	if (err)  {				/* if we didn't timeout... */
674 		IFNET_STAT_INC(ifp, oerrors, 1);
675 		lprintf("X");
676 	} else {
677 		IFNET_STAT_INC(ifp, opackets, 1);
678 		IFNET_STAT_INC(ifp, obytes, m->m_pkthdr.len);
679 		if (ifp->if_bpf)
680 		    lptap(ifp, m);
681 	}
682 
683 	m_freem(m);
684 
685 	if (!(ppb_rstr(ppbus) & CLPIP_SHAKE)) {
686 		lprintf("^");
687 		lp_intr(dev);
688 	}
689 	crit_exit();
690 	return 0;
691     }
692 
693     if (ppb_rstr(ppbus) & LPIP_SHAKE) {
694         lprintf("&");
695         lp_intr(dev);
696     }
697 
698     if (lpoutbyte(0x08, LPMAXSPIN1, ppbus))
699         goto end;
700     if (lpoutbyte(0x00, LPMAXSPIN2, ppbus))
701         goto end;
702 
703     mm = m;
704     do {
705         cp = mtod(mm,u_char *);
706 	len = mm->m_len;
707         while (len--)
708 	    if (lpoutbyte(*cp++, LPMAXSPIN2, ppbus))
709 	        goto end;
710     } while ((mm = mm->m_next));
711 
712     err = 0;				/* no errors were encountered */
713 
714     end:
715     --cp;
716     ppb_wdtr(ppbus, txmitl[*cp] ^ 0x17);
717 
718     if (err)  {				/* if we didn't timeout... */
719 	IFNET_STAT_INC(ifp, oerrors, 1);
720         lprintf("X");
721     } else {
722 	IFNET_STAT_INC(ifp, opackets, 1);
723 	IFNET_STAT_INC(ifp, obytes, m->m_pkthdr.len);
724 	if (ifp->if_bpf)
725 	    lptap(ifp, m);
726     }
727 
728     m_freem(m);
729 
730     if (ppb_rstr(ppbus) & LPIP_SHAKE) {
731 	lprintf("^");
732 	lp_intr(dev);
733     }
734 
735     crit_exit();
736     return 0;
737 }
738 
739 /*
740  * Because plip is a static device that always exists under any attached
741  * ppbus device, and not scanned by the ppbus device, we need an identify
742  * function to install the device.
743  */
744 static device_method_t lp_methods[] = {
745   	/* device interface */
746 	DEVMETHOD(device_identify,	bus_generic_identify),
747 	DEVMETHOD(device_probe,		lp_probe),
748 	DEVMETHOD(device_attach,	lp_attach),
749 
750 	DEVMETHOD_END
751 };
752 
753 static driver_t lp_driver = {
754   "plip",
755   lp_methods,
756   sizeof(struct lp_data),
757 };
758 
759 DECLARE_DUMMY_MODULE(if_plip);
760 DRIVER_MODULE(if_plip, ppbus, lp_driver, lp_devclass, NULL, NULL);
761 
762