1/*-
2 * Copyright (c) 1990 William F. Jolitz, TeleMuse
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 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This software is a component of "386BSD" developed by
16 *	William F. Jolitz, TeleMuse.
17 * 4. Neither the name of the developer nor the name "386BSD"
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS A COMPONENT OF 386BSD DEVELOPED BY WILLIAM F. JOLITZ
22 * AND IS INTENDED FOR RESEARCH AND EDUCATIONAL PURPOSES ONLY. THIS
23 * SOFTWARE SHOULD NOT BE CONSIDERED TO BE A COMMERCIAL PRODUCT.
24 * THE DEVELOPER URGES THAT USERS WHO REQUIRE A COMMERCIAL PRODUCT
25 * NOT MAKE USE OF THIS WORK.
26 *
27 * FOR USERS WHO WISH TO UNDERSTAND THE 386BSD SYSTEM DEVELOPED
28 * BY WILLIAM F. JOLITZ, WE RECOMMEND THE USER STUDY WRITTEN
29 * REFERENCES SUCH AS THE  "PORTING UNIX TO THE 386" SERIES
30 * (BEGINNING JANUARY 1991 "DR. DOBBS JOURNAL", USA AND BEGINNING
31 * JUNE 1991 "UNIX MAGAZIN", GERMANY) BY WILLIAM F. JOLITZ AND
32 * LYNNE GREER JOLITZ, AS WELL AS OTHER BOOKS ON UNIX AND THE
33 * ON-LINE 386BSD USER MANUAL BEFORE USE. A BOOK DISCUSSING THE INTERNALS
34 * OF 386BSD ENTITLED "386BSD FROM THE INSIDE OUT" WILL BE AVAILABLE LATE 1992.
35 *
36 * THIS SOFTWARE IS PROVIDED BY THE DEVELOPER ``AS IS'' AND
37 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
38 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
39 * ARE DISCLAIMED.  IN NO EVENT SHALL THE DEVELOPER BE LIABLE
40 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
41 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
42 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
43 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
44 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
45 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
46 * SUCH DAMAGE.
47 *
48 *	from: unknown origin, 386BSD 0.1
49 * $FreeBSD$
50 */
51
52/*
53 * Device Driver for AT parallel printer port
54 * Written by William Jolitz 12/18/90
55 */
56
57/*
58 * Parallel port TCP/IP interfaces added.  I looked at the driver from
59 * MACH but this is a complete rewrite, and btw. incompatible, and it
60 * should perform better too.  I have never run the MACH driver though.
61 *
62 * This driver sends two bytes (0x08, 0x00) in front of each packet,
63 * to allow us to distinguish another format later.
64 *
65 * Now added a Linux/Crynwr compatibility mode which is enabled using
66 * IF_LINK0 - Tim Wilkinson.
67 *
68 * TODO:
69 *    Make HDLC/PPP mode, use IF_LLC1 to enable.
70 *
71 * Connect the two computers using a Laplink parallel cable to use this
72 * feature:
73 *
74 *      +----------------------------------------+
75 * 	|A-name	A-End	B-End	Descr.	Port/Bit |
76 *      +----------------------------------------+
77 *	|DATA0	2	15	Data	0/0x01   |
78 *	|-ERROR	15	2	   	1/0x08   |
79 *      +----------------------------------------+
80 *	|DATA1	3	13	Data	0/0x02	 |
81 *	|+SLCT	13	3	   	1/0x10   |
82 *      +----------------------------------------+
83 *	|DATA2	4	12	Data	0/0x04   |
84 *	|+PE	12	4	   	1/0x20   |
85 *      +----------------------------------------+
86 *	|DATA3	5	10	Strobe	0/0x08   |
87 *	|-ACK	10	5	   	1/0x40   |
88 *      +----------------------------------------+
89 *	|DATA4	6	11	Data	0/0x10   |
90 *	|BUSY	11	6	   	1/~0x80  |
91 *      +----------------------------------------+
92 *	|GND	18-25	18-25	GND	-        |
93 *      +----------------------------------------+
94 *
95 * Expect transfer-rates up to 75 kbyte/sec.
96 *
97 * If GCC could correctly grok
98 *	register int port asm("edx")
99 * the code would be cleaner
100 *
101 * Poul-Henning Kamp <phk@freebsd.org>
102 */
103
104#include <sys/param.h>
105#include <sys/systm.h>
106#include <sys/conf.h>
107#include <sys/bus.h>
108#include <sys/kernel.h>
109#include <sys/module.h>
110#include <sys/uio.h>
111#include <sys/syslog.h>
112#include <sys/malloc.h>
113
114#include <machine/bus.h>
115#include <machine/resource.h>
116#include <sys/rman.h>
117
118#include <isa/isavar.h>
119
120#include <pc98/cbus/olptreg.h>
121#include <dev/ppbus/lptio.h>
122
123#define	LPINITRDY	4	/* wait up to 4 seconds for a ready */
124#define	LPTOUTINITIAL	10	/* initial timeout to wait for ready 1/10 s */
125#define	LPTOUTMAX	1	/* maximal timeout 1 s */
126#define	LPPRI		(PZERO+8)
127#define	BUFSIZE		1024
128
129#ifndef DEBUG
130#define lprintf(args)
131#else
132#define lprintf(args)	do {				\
133				if (lptflag)		\
134					printf args;	\
135			} while (0)
136static int volatile lptflag = 1;
137#endif
138
139struct lpt_softc {
140	struct resource *res_port;
141	struct resource *res_irq;
142	void *sc_ih;
143	struct callout timer;
144
145	int	sc_port;
146	short	sc_state;
147	/* default case: negative prime, negative ack, handshake strobe,
148	   prime once */
149	u_char	sc_control;
150	char	sc_flags;
151#define LP_POS_INIT	0x04	/* if we are a postive init signal */
152#define LP_POS_ACK	0x08	/* if we are a positive going ack */
153#define LP_NO_PRIME	0x10	/* don't prime the printer at all */
154#define LP_PRIMEOPEN	0x20	/* prime on every open */
155#define LP_AUTOLF	0x40	/* tell printer to do an automatic lf */
156#define LP_BYPASS	0x80	/* bypass  printer ready checks */
157	void	*sc_inbuf;
158	short	sc_xfercnt ;
159	char	sc_primed;
160	char	*sc_cp ;
161	u_char	sc_irq ;	/* IRQ status of port */
162#define LP_HAS_IRQ	0x01	/* we have an irq available */
163#define LP_USE_IRQ	0x02	/* we are using our irq */
164#define LP_ENABLE_IRQ	0x04	/* enable IRQ on open */
165	u_char	sc_backoff ;	/* time to call lptout() again */
166};
167
168/* bits for state */
169#define	OPEN		(1<<0)	/* device is open */
170#define	ASLP		(1<<1)	/* awaiting draining of printer */
171#define	ERROR		(1<<2)	/* error was received from printer */
172#define	OBUSY		(1<<3)	/* printer is busy doing output */
173#define LPTOUT		(1<<4)	/* timeout while not selected */
174#define TOUT		(1<<5)	/* timeout while not selected */
175#define INIT		(1<<6)	/* waiting to initialize for open */
176#define INTERRUPTED	(1<<7)	/* write call was interrupted */
177
178
179/* status masks to interrogate printer status */
180#define RDY_MASK	(LPS_SEL|LPS_OUT|LPS_NBSY|LPS_NERR)	/* ready ? */
181#define LP_READY	(LPS_SEL|LPS_NBSY|LPS_NERR)
182
183/* Printer Ready condition  - from lpa.c */
184/* Only used in polling code */
185#define	NOT_READY(x)	((inb(x) & LPS_NBSY) != LPS_NBSY)
186
187#define	MAX_SLEEP	(hz*5)	/* Timeout while waiting for device ready */
188#define	MAX_SPIN	20	/* Max delay for device ready in usecs */
189
190static timeout_t lptout;
191static int lpt_probe(device_t);
192static int lpt_attach(device_t);
193static void lpt_intr(void *);
194
195static devclass_t olpt_devclass;
196
197static device_method_t olpt_methods[] = {
198	DEVMETHOD(device_probe,		lpt_probe),
199	DEVMETHOD(device_attach,	lpt_attach),
200	{ 0, 0 }
201};
202
203static driver_t olpt_driver = {
204	"olpt",
205	olpt_methods,
206	sizeof (struct lpt_softc),
207};
208
209DRIVER_MODULE(olpt, isa, olpt_driver, olpt_devclass, 0, 0);
210
211static	d_open_t	lptopen;
212static	d_close_t	lptclose;
213static	d_write_t	lptwrite;
214static	d_ioctl_t	lptioctl;
215
216static struct cdevsw lpt_cdevsw = {
217	.d_version =	D_VERSION,
218	.d_flags =	D_NEEDGIANT,
219	.d_open =	lptopen,
220	.d_close =	lptclose,
221	.d_write =	lptwrite,
222	.d_ioctl =	lptioctl,
223	.d_name =	"lpt",
224};
225
226static bus_addr_t lpt_iat[] = {0, 2, 4, 6};
227
228/*
229 * New lpt port probe Geoff Rehmet - Rhodes University - 14/2/94
230 * Based partially on Rod Grimes' printer probe
231 *
232 * Logic:
233 *	1) If no port address was given, use the bios detected ports
234 *	   and autodetect what ports the printers are on.
235 *	2) Otherwise, probe the data port at the address given,
236 *	   using the method in Rod Grimes' port probe.
237 *	   (Much code ripped off directly from Rod's probe.)
238 *
239 * Comments from Rod's probe:
240 * Logic:
241 *	1) You should be able to write to and read back the same value
242 *	   to the data port.  Do an alternating zeros, alternating ones,
243 *	   walking zero, and walking one test to check for stuck bits.
244 *
245 *	2) You should be able to write to and read back the same value
246 *	   to the control port lower 5 bits, the upper 3 bits are reserved
247 *	   per the IBM PC technical reference manauls and different boards
248 *	   do different things with them.  Do an alternating zeros, alternating
249 *	   ones, walking zero, and walking one test to check for stuck bits.
250 *
251 *	   Some printers drag the strobe line down when the are powered off
252 * 	   so this bit has been masked out of the control port test.
253 *
254 *	   XXX Some printers may not like a fast pulse on init or strobe, I
255 *	   don't know at this point, if that becomes a problem these bits
256 *	   should be turned off in the mask byte for the control port test.
257 *
258 *	   We are finally left with a mask of 0x14, due to some printers
259 *	   being adamant about holding other bits high ........
260 *
261 *	   Before probing the control port, we write a 0 to the data port -
262 *	   If not, some printers chuck out garbage when the strobe line
263 *	   gets toggled.
264 *
265 *	3) Set the data and control ports to a value of 0
266 *
267 *	This probe routine has been tested on Epson Lx-800, HP LJ3P,
268 *	Epson FX-1170 and C.Itoh 8510RM
269 *	printers.
270 *	Quick exit on fail added.
271 */
272
273int
274lpt_probe(device_t dev)
275{
276#define PC98_OLD_LPT 0x40
277#define PC98_IEEE_1284_FUNCTION 0x149
278	int rid;
279	struct resource *res;
280
281	/* Check isapnp ids */
282	if (isa_get_vendorid(dev))
283		return ENXIO;
284
285	rid = 0;
286	res = isa_alloc_resourcev(dev, SYS_RES_IOPORT, &rid, lpt_iat, 4,
287				  RF_ACTIVE);
288	if (res == NULL)
289		return ENXIO;
290	isa_load_resourcev(res, lpt_iat, 4);
291
292	if (isa_get_port(dev) == PC98_OLD_LPT) {
293		unsigned int pc98_ieee_mode, tmp;
294
295		tmp = inb(PC98_IEEE_1284_FUNCTION);
296		pc98_ieee_mode = tmp;
297		if ((tmp & 0x10) == 0x10) {
298			outb(PC98_IEEE_1284_FUNCTION, tmp & ~0x10);
299			tmp = inb(PC98_IEEE_1284_FUNCTION);
300			if ((tmp & 0x10) != 0x10) {
301				outb(PC98_IEEE_1284_FUNCTION, pc98_ieee_mode);
302				bus_release_resource(dev, SYS_RES_IOPORT, rid,
303						     res);
304				return ENXIO;
305			}
306		}
307	}
308
309	bus_release_resource(dev, SYS_RES_IOPORT, rid, res);
310	return 0;
311}
312
313/* XXX Todo - try and detect if interrupt is working */
314int
315lpt_attach(device_t dev)
316{
317	int	rid, unit;
318	struct	lpt_softc	*sc;
319	struct	cdev		*cdev;
320
321	unit = device_get_unit(dev);
322	sc = device_get_softc(dev);
323	callout_init(&sc->timer, 0);
324
325	rid = 0;
326	sc->res_port = isa_alloc_resourcev(dev, SYS_RES_IOPORT, &rid,
327					   lpt_iat, 4, RF_ACTIVE);
328	if (sc->res_port == NULL)
329		return ENXIO;
330	isa_load_resourcev(sc->res_port, lpt_iat, 4);
331
332	sc->sc_port = rman_get_start(sc->res_port);
333	sc->sc_primed = 0;	/* not primed yet */
334
335	outb(sc->sc_port+lpt_pstb_ctrl,	LPC_DIS_PSTB);	/* PSTB disable */
336	outb(sc->sc_port+lpt_control,	LPC_MODE8255);	/* 8255 mode set */
337	outb(sc->sc_port+lpt_control,	LPC_NIRQ8);	/* IRQ8 inactive */
338	outb(sc->sc_port+lpt_control,	LPC_NPSTB);	/* PSTB inactive */
339	outb(sc->sc_port+lpt_pstb_ctrl,	LPC_EN_PSTB);	/* PSTB enable */
340
341	sc->sc_irq = 0;
342	if (isa_get_irq(dev) != -1) {
343		rid = 0;
344		sc->res_irq = bus_alloc_resource_any(dev, SYS_RES_IRQ, &rid,
345						     RF_ACTIVE);
346		if (sc->res_irq == NULL) {
347			bus_release_resource(dev, SYS_RES_IOPORT, 0,
348					     sc->res_port);
349			return ENXIO;
350		}
351		if (bus_setup_intr(dev, sc->res_irq, INTR_TYPE_TTY, NULL, lpt_intr,
352				   sc, &sc->sc_ih)) {
353			bus_release_resource(dev, SYS_RES_IOPORT, 0,
354					     sc->res_port);
355			bus_release_resource(dev, SYS_RES_IRQ, 0,
356					     sc->res_irq);
357			return ENXIO;
358		}
359		sc->sc_irq = LP_HAS_IRQ | LP_USE_IRQ | LP_ENABLE_IRQ;
360		device_printf(dev, "Interrupt-driven port");
361	}
362
363	cdev = make_dev(&lpt_cdevsw, 0,
364			UID_ROOT, GID_WHEEL, 0600, "lpt%d", unit);
365	cdev->si_drv1 = sc;
366	cdev = make_dev(&lpt_cdevsw, LP_BYPASS,
367			UID_ROOT, GID_WHEEL, 0600, "lpctl%d", unit);
368	cdev->si_drv1 = sc;
369
370	return 0;
371}
372
373/*
374 * lptopen -- reset the printer, then wait until it's selected and not busy.
375 *	If LP_BYPASS flag is selected, then we do not try to select the
376 *	printer -- this is just used for passing ioctls.
377 */
378
379static	int
380lptopen (struct cdev *dev, int flags, int fmt, struct thread *td)
381{
382	struct lpt_softc *sc = dev->si_drv1;
383	int s;
384	int port;
385
386	if (sc->sc_port == 0)
387		return (ENXIO);
388
389	if (sc->sc_state) {
390		lprintf(("lp: still open %x\n", sc->sc_state));
391		return(EBUSY);
392	} else
393		sc->sc_state |= INIT;
394
395	sc->sc_flags = dev2unit(dev);
396
397	/* Check for open with BYPASS flag set. */
398	if (sc->sc_flags & LP_BYPASS) {
399		sc->sc_state = OPEN;
400		return(0);
401	}
402
403	s = spltty();
404	lprintf(("lp flags 0x%x\n", sc->sc_flags));
405	port = sc->sc_port;
406
407	/* set IRQ status according to ENABLE_IRQ flag */
408	if (sc->sc_irq & LP_ENABLE_IRQ)
409		sc->sc_irq |= LP_USE_IRQ;
410	else
411		sc->sc_irq &= ~LP_USE_IRQ;
412
413	/* init printer */
414	sc->sc_state = OPEN;
415	sc->sc_inbuf = malloc(BUFSIZE, M_DEVBUF, M_WAITOK);
416	sc->sc_xfercnt = 0;
417	splx(s);
418
419	/* only use timeout if using interrupt */
420	lprintf(("irq %x\n", sc->sc_irq));
421	if (sc->sc_irq & LP_USE_IRQ) {
422		sc->sc_state |= TOUT;
423		sc->sc_backoff = hz / LPTOUTINITIAL;
424		callout_reset(&sc->timer, sc->sc_backoff, lptout, sc);
425	}
426
427	lprintf(("opened.\n"));
428	return(0);
429}
430
431static void
432lptout (void *arg)
433{
434	struct lpt_softc *sc = arg;
435	int pl;
436
437	lprintf(("T %x ", inb(sc->sc_port+lpt_status)));
438	if (sc->sc_state & OPEN) {
439		sc->sc_backoff++;
440		if (sc->sc_backoff > hz/LPTOUTMAX)
441			sc->sc_backoff = sc->sc_backoff > hz/LPTOUTMAX;
442		callout_reset(&sc->timer, sc->sc_backoff, lptout, sc);
443	} else
444		sc->sc_state &= ~TOUT;
445
446	if (sc->sc_state & ERROR)
447		sc->sc_state &= ~ERROR;
448
449	/*
450	 * Avoid possible hangs do to missed interrupts
451	 */
452	if (sc->sc_xfercnt) {
453		pl = spltty();
454		lpt_intr(sc);
455		splx(pl);
456	} else {
457		sc->sc_state &= ~OBUSY;
458		wakeup(sc);
459	}
460}
461
462/*
463 * lptclose -- close the device, free the local line buffer.
464 *
465 * Check for interrupted write call added.
466 */
467
468static	int
469lptclose(struct cdev *dev, int flags, int fmt, struct thread *td)
470{
471	struct lpt_softc *sc = dev->si_drv1;
472
473	if(sc->sc_flags & LP_BYPASS)
474		goto end_close;
475
476	sc->sc_state &= ~OPEN;
477	free(sc->sc_inbuf, M_DEVBUF);
478
479end_close:
480	sc->sc_state = 0;
481	sc->sc_xfercnt = 0;
482	lprintf(("closed.\n"));
483	return(0);
484}
485
486/*
487 * pushbytes()
488 *	Workhorse for actually spinning and writing bytes to printer
489 *	Derived from lpa.c
490 *	Originally by ?
491 *
492 *	This code is only used when we are polling the port
493 */
494static int
495pushbytes(struct lpt_softc * sc)
496{
497	int spin, err, tic;
498	char ch;
499	int port = sc->sc_port;
500
501	lprintf(("p"));
502	/* loop for every character .. */
503	while (sc->sc_xfercnt > 0) {
504		/* printer data */
505		ch = *(sc->sc_cp);
506		sc->sc_cp++;
507		sc->sc_xfercnt--;
508
509		/*
510		 * Wait for printer ready.
511		 * Loop 20 usecs testing BUSY bit, then sleep
512		 * for exponentially increasing timeout. (vak)
513		 */
514		for (spin=0; NOT_READY(port+lpt_status) && spin<MAX_SPIN; ++spin)
515			DELAY(1);	/* XXX delay is NOT this accurate! */
516		if (spin >= MAX_SPIN) {
517			tic = 0;
518			while (NOT_READY(port+lpt_status)) {
519				/*
520				 * Now sleep, every cycle a
521				 * little longer ..
522				 */
523				tic = tic + tic + 1;
524				/*
525				 * But no more than 10 seconds. (vak)
526				 */
527				if (tic > MAX_SLEEP)
528					tic = MAX_SLEEP;
529				err = tsleep(sc, LPPRI,
530					"lptpoll", tic);
531				if (err != EWOULDBLOCK) {
532					return (err);
533				}
534			}
535		}
536
537		/* output data */
538		outb(port+lpt_data, ch);
539		DELAY(1);
540		outb(port+lpt_control, LPC_PSTB);
541		DELAY(1);
542		outb(port+lpt_control, LPC_NPSTB);
543	}
544	return(0);
545}
546
547/*
548 * lptwrite --copy a line from user space to a local buffer, then call
549 * putc to get the chars moved to the output queue.
550 *
551 * Flagging of interrupted write added.
552 */
553
554static	int
555lptwrite(struct cdev *dev, struct uio * uio, int ioflag)
556{
557	register unsigned n;
558	int pl, err;
559	struct lpt_softc *sc = dev->si_drv1;
560
561	if(sc->sc_flags & LP_BYPASS) {
562		/* we can't do writes in bypass mode */
563		return(EPERM);
564	}
565
566	sc->sc_state &= ~INTERRUPTED;
567	while ((n = min(BUFSIZE, uio->uio_resid)) != 0) {
568		sc->sc_cp = sc->sc_inbuf;
569		uiomove(sc->sc_cp, n, uio);
570		sc->sc_xfercnt = n ;
571		while ((sc->sc_xfercnt > 0)&&(sc->sc_irq & LP_USE_IRQ)) {
572			lprintf(("i"));
573			/* if the printer is ready for a char, */
574			/* give it one */
575			if ((sc->sc_state & OBUSY) == 0){
576				lprintf(("\nC %d. ", sc->sc_xfercnt));
577				pl = spltty();
578				lpt_intr(sc);
579				(void) splx(pl);
580			}
581			lprintf(("W "));
582			if (sc->sc_state & OBUSY)
583				if ((err = tsleep (sc,
584					 LPPRI|PCATCH, "lpwrite", 0))) {
585					sc->sc_state |= INTERRUPTED;
586					return(err);
587				}
588		}
589		/* check to see if we must do a polled write */
590		if(!(sc->sc_irq & LP_USE_IRQ) && (sc->sc_xfercnt)) {
591			lprintf(("p"));
592			if((err = pushbytes(sc)))
593				return(err);
594		}
595	}
596	return(0);
597}
598
599/*
600 * lptintr -- handle printer interrupts which occur when the printer is
601 * ready to accept another char.
602 *
603 * do checking for interrupted write call.
604 */
605
606static void
607lpt_intr(void *arg)
608{
609}
610
611static	int
612lptioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags, struct thread *td)
613{
614	int	error = 0;
615	struct lpt_softc *sc = dev->si_drv1;
616	u_char	old_sc_irq;	/* old printer IRQ status */
617
618	switch (cmd) {
619	case LPT_IRQ :
620		if(sc->sc_irq & LP_HAS_IRQ) {
621			/*
622			 * NOTE:
623			 * If the IRQ status is changed,
624			 * this will only be visible on the
625			 * next open.
626			 *
627			 * If interrupt status changes,
628			 * this gets syslog'd.
629			 */
630			old_sc_irq = sc->sc_irq;
631			if(*(int*)data == 0)
632				sc->sc_irq &= (~LP_ENABLE_IRQ);
633			else
634				sc->sc_irq |= LP_ENABLE_IRQ;
635			if (old_sc_irq != sc->sc_irq )
636				log(LOG_NOTICE, "%s switched to %s mode\n",
637					devtoname(dev),
638					(sc->sc_irq & LP_ENABLE_IRQ)?
639					"interrupt-driven":"polled");
640		} else /* polled port */
641			error = EOPNOTSUPP;
642		break;
643	default:
644		error = ENODEV;
645	}
646
647	return(error);
648}
649