text: /*
   * Copyright (c) 1990 William F. Jolitz, TeleMuse
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *	This software is a component of "386BSD" developed by
   *	William F. Jolitz, TeleMuse.
   * 4. Neither the name of the developer nor the name "386BSD"
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS A COMPONENT OF 386BSD DEVELOPED BY WILLIAM F. JOLITZ
   * AND IS INTENDED FOR RESEARCH AND EDUCATIONAL PURPOSES ONLY. THIS
   * SOFTWARE SHOULD NOT BE CONSIDERED TO BE A COMMERCIAL PRODUCT.
   * THE DEVELOPER URGES THAT USERS WHO REQUIRE A COMMERCIAL PRODUCT
   * NOT MAKE USE OF THIS WORK.
   *
   * FOR USERS WHO WISH TO UNDERSTAND THE 386BSD SYSTEM DEVELOPED
   * BY WILLIAM F. JOLITZ, WE RECOMMEND THE USER STUDY WRITTEN
   * REFERENCES SUCH AS THE  "PORTING UNIX TO THE 386" SERIES
   * (BEGINNING JANUARY 1991 "DR. DOBBS JOURNAL", USA AND BEGINNING
   * JUNE 1991 "UNIX MAGAZIN", GERMANY) BY WILLIAM F. JOLITZ AND
   * LYNNE GREER JOLITZ, AS WELL AS OTHER BOOKS ON UNIX AND THE
   * ON-LINE 386BSD USER MANUAL BEFORE USE. A BOOK DISCUSSING THE INTERNALS
   * OF 386BSD ENTITLED "386BSD FROM THE INSIDE OUT" WILL BE AVAILABLE LATE 1992.
   *
   * THIS SOFTWARE IS PROVIDED BY THE DEVELOPER ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE DEVELOPER BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   *	from: unknown origin, 386BSD 0.1
   *	From Id: lpt.c,v 1.55.2.1 1996/11/12 09:08:38 phk Exp
   *	From Id: nlpt.c,v 1.14 1999/02/08 13:55:43 des Exp
   *	$Id: lpt.c,v 1.2.2.1 1999/04/24 02:20:22 obrien Exp $
   */
  
  /*
   * Device Driver for AT parallel printer port
   * Written by William Jolitz 12/18/90
   */
  
  /*
   * Updated for ppbus by Nicolas Souchu
   * [Mon Jul 28 1997]
   */
  
  
  #ifdef KERNEL
  #include "opt_devfs.h"
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/conf.h>
  #include <sys/buf.h>
  #include <sys/kernel.h>
  #include <sys/uio.h>
  #include <sys/syslog.h>
  #ifdef DEVFS
  #include <sys/devfsext.h>
  #endif /*DEVFS*/
  #include <sys/malloc.h>
  
  #include <machine/clock.h>
  #include <machine/lpt.h>
  #endif /*KERNEL*/
  
  #include <dev/ppbus/ppbconf.h>
  #include <dev/ppbus/ppb_1284.h>
  #include <dev/ppbus/lpt.h>
  
  #include "opt_lpt.h"
  
  #ifndef LPT_DEBUG
  #define lprintf(args)
  #else
  #define lprintf(args)						\
  		do {						\
  			if (lptflag)				\
  				printf args;			\
  		} while (0)
  static int volatile lptflag = 1;
  #endif
  
  #define	LPINITRDY	4	/* wait up to 4 seconds for a ready */
  #define	LPTOUTINITIAL	10	/* initial timeout to wait for ready 1/10 s */
  #define	LPTOUTMAX	1	/* maximal timeout 1 s */
  #define	LPPRI		(PZERO+8)
  #define	BUFSIZE		1024
  #define	BUFSTATSIZE	32
  
  #define	LPTUNIT(s)	((s)&0x03)
  #define	LPTFLAGS(s)	((s)&0xfc)
  
  struct lpt_data {
  	unsigned short lpt_unit;
  
  	struct ppb_device lpt_dev;
  
  	short	sc_state;
  	/* default case: negative prime, negative ack, handshake strobe,
  	   prime once */
  	u_char	sc_control;
  	char	sc_flags;
  #define LP_POS_INIT	0x04	/* if we are a postive init signal */
  #define LP_POS_ACK	0x08	/* if we are a positive going ack */
  #define LP_NO_PRIME	0x10	/* don't prime the printer at all */
  #define LP_PRIMEOPEN	0x20	/* prime on every open */
  #define LP_AUTOLF	0x40	/* tell printer to do an automatic lf */
  #define LP_BYPASS	0x80	/* bypass  printer ready checks */
  	struct	buf *sc_inbuf;
  	struct	buf *sc_statbuf;
  	short	sc_xfercnt ;
  	char	sc_primed;
  	char	*sc_cp ;
  	u_short	sc_irq ;	/* IRQ status of port */
  #define LP_HAS_IRQ	0x01	/* we have an irq available */
  #define LP_USE_IRQ	0x02	/* we are using our irq */
  #define LP_ENABLE_IRQ	0x04	/* enable IRQ on open */
  #define LP_ENABLE_EXT	0x10	/* we shall use advanced mode when possible */
  	u_char	sc_backoff ;	/* time to call lptout() again */
  
  #ifdef DEVFS
  	void	*devfs_token;
  	void	*devfs_token_ctl;
  #endif
  };
  
  static int	nlpt = 0;
  #define MAXLPT	8			/* XXX not much better! */
  static struct lpt_data *lptdata[MAXLPT];
  
  #define LPT_NAME	"lpt"		/* our official name */
  
  static timeout_t lptout;
  static int	lpt_port_test(struct lpt_data *sc, u_char data, u_char mask);
  static int	lpt_detect(struct lpt_data *sc);
  
  /*
   * Make ourselves visible as a ppbus driver
   */
  
  static struct ppb_device	*lptprobe(struct ppb_data *ppb);
  static int			lptattach(struct ppb_device *dev);
  static void			lptintr(int unit);
  static void			lpt_drvinit(void *unused);
  
  static void			lpt_intr(int unit);	/* without spls */
  
  #ifdef KERNEL
  
  static struct ppb_driver lptdriver = {
      lptprobe, lptattach, LPT_NAME
  };
  DATA_SET(ppbdriver_set, lptdriver);
  
  #endif /* KERNEL */
  
  /* bits for state */
  #define	OPEN		(1<<0)	/* device is open */
  #define	ASLP		(1<<1)	/* awaiting draining of printer */
  #define	EERROR		(1<<2)	/* error was received from printer */
  #define	OBUSY		(1<<3)	/* printer is busy doing output */
  #define LPTOUT		(1<<4)	/* timeout while not selected */
  #define TOUT		(1<<5)	/* timeout while not selected */
  #define LPTINIT		(1<<6)	/* waiting to initialize for open */
  #define INTERRUPTED	(1<<7)	/* write call was interrupted */
  
  #define HAVEBUS		(1<<8)	/* the driver owns the bus */
  
  
  /* status masks to interrogate printer status */
  #define RDY_MASK	(LPS_SEL|LPS_OUT|LPS_NBSY|LPS_NERR)	/* ready ? */
  #define LP_READY	(LPS_SEL|LPS_NBSY|LPS_NERR)
  
  /* Printer Ready condition  - from lpa.c */
  /* Only used in polling code */
  #define	LPS_INVERT	(LPS_NBSY | LPS_NACK |           LPS_SEL | LPS_NERR)
  #define	LPS_MASK	(LPS_NBSY | LPS_NACK | LPS_OUT | LPS_SEL | LPS_NERR)
  #define	NOT_READY(lpt)	((ppb_rstr(&(lpt)->lpt_dev)^LPS_INVERT)&LPS_MASK)
  
  #define	MAX_SLEEP	(hz*5)	/* Timeout while waiting for device ready */
  #define	MAX_SPIN	20	/* Max delay for device ready in usecs */
  
  
  static	d_open_t	lptopen;
  static	d_close_t	lptclose;
  static	d_write_t	lptwrite;
  static	d_read_t	lptread;
  static	d_ioctl_t	lptioctl;
  
  #define CDEV_MAJOR 16
  static struct cdevsw lpt_cdevsw = 
  	{ lptopen,	lptclose,	lptread,	lptwrite,	/*16*/
  	  lptioctl,	nullstop,	nullreset,	nodevtotty,	/* lpt */
  	  seltrue,	nommap,		nostrat,	LPT_NAME,	NULL,	-1 };
  
  static int
  lpt_request_ppbus(struct lpt_data *sc, int how)
  {
  	int error;
  
  	if (sc->sc_state & HAVEBUS)
  		return (0);
  
  	/* we have the bus only if the request succeded */
  	if ((error = ppb_request_bus(&sc->lpt_dev, how)) == 0)
  		sc->sc_state |= HAVEBUS;
  
  	return (error);
  }
  
  static int
  lpt_release_ppbus(struct lpt_data *sc)
  {
  	ppb_release_bus(&sc->lpt_dev);
  	sc->sc_state &= ~HAVEBUS;
  
  	return (0);
  }
  
  /*
   * Internal routine to lptprobe to do port tests of one byte value
   */
  static int
  lpt_port_test(struct lpt_data *sc, u_char data, u_char mask)
  {
  	int	temp, timeout;
  
  	data = data & mask;
  	ppb_wdtr(&sc->lpt_dev, data);
  	timeout = 10000;
  	do {
  		DELAY(10);
  		temp = ppb_rdtr(&sc->lpt_dev) & mask;
  	}
  	while (temp != data && --timeout);
  	lprintf(("out=%x\tin=%x\ttout=%d\n", data, temp, timeout));
  	return (temp == data);
  }
  
  /*
   * Probe simplified by replacing multiple loops with a hardcoded
   * test pattern - 1999/02/08 des@freebsd.org
   *
   * New lpt port probe Geoff Rehmet - Rhodes University - 14/2/94
   * Based partially on Rod Grimes' printer probe
   *
   * Logic:
   *	1) If no port address was given, use the bios detected ports
   *	   and autodetect what ports the printers are on.
   *	2) Otherwise, probe the data port at the address given,
   *	   using the method in Rod Grimes' port probe.
   *	   (Much code ripped off directly from Rod's probe.)
   *
   * Comments from Rod's probe:
   * Logic:
   *	1) You should be able to write to and read back the same value
   *	   to the data port.  Do an alternating zeros, alternating ones,
   *	   walking zero, and walking one test to check for stuck bits.
   *
   *	2) You should be able to write to and read back the same value
   *	   to the control port lower 5 bits, the upper 3 bits are reserved
   *	   per the IBM PC technical reference manauls and different boards
   *	   do different things with them.  Do an alternating zeros, alternating
   *	   ones, walking zero, and walking one test to check for stuck bits.
   *
   *	   Some printers drag the strobe line down when the are powered off
   * 	   so this bit has been masked out of the control port test.
   *
   *	   XXX Some printers may not like a fast pulse on init or strobe, I
   *	   don't know at this point, if that becomes a problem these bits
   *	   should be turned off in the mask byte for the control port test.
   *
   *	   We are finally left with a mask of 0x14, due to some printers
   *	   being adamant about holding other bits high ........
   *
   *	   Before probing the control port, we write a 0 to the data port -
   *	   If not, some printers chuck out garbage when the strobe line
   *	   gets toggled.
   *
   *	3) Set the data and control ports to a value of 0
   *
   *	This probe routine has been tested on Epson Lx-800, HP LJ3P,
   *	Epson FX-1170 and C.Itoh 8510RM
   *	printers.
   *	Quick exit on fail added.
   */
  static int
  lpt_detect(struct lpt_data *sc)
  {
  	static u_char	testbyte[18] = {
  		0x55,			/* alternating zeros */
  		0xaa,			/* alternating ones */
  		0xfe, 0xfd, 0xfb, 0xf7,
  		0xef, 0xdf, 0xbf, 0x7f,	/* walking zero */
  		0x01, 0x02, 0x04, 0x08,
  		0x10, 0x20, 0x40, 0x80	/* walking one */
  	};
  	int		i, error, status;
  
  	status = 1;				/* assume success */
  
  	if ((error = lpt_request_ppbus(sc, PPB_DONTWAIT))) {
  		printf(LPT_NAME ": cannot alloc ppbus (%d)!\n", error);
  		status = 0;
  		goto end_probe;
  	}
  
  	for (i = 0; i < 18 && status; i++)
  		if (!lpt_port_test(sc, testbyte[i], 0xff)) {
  			status = 0;
  			goto end_probe;
  		}
  
  end_probe:
  	/* write 0's to control and data ports */
  	ppb_wdtr(&sc->lpt_dev, 0);
  	ppb_wctr(&sc->lpt_dev, 0);
  
  	lpt_release_ppbus(sc);
  
  	return (status);
  }
  
  /*
   * lptprobe()
   */
  static struct ppb_device *
  lptprobe(struct ppb_data *ppb)
  {
  	struct lpt_data *sc;
  
  	sc = (struct lpt_data *) malloc(sizeof(struct lpt_data),
  							M_TEMP, M_NOWAIT);
  	if (!sc) {
  		printf(LPT_NAME ": cannot malloc!\n");
  		return (0);
  	}
  	bzero(sc, sizeof(struct lpt_data));
  
  	lptdata[nlpt] = sc;
  
  	/*
  	 * lpt dependent initialisation.
  	 */
  	sc->lpt_unit = nlpt;
  
  	/*
  	 * ppbus dependent initialisation.
  	 */
  	sc->lpt_dev.id_unit = sc->lpt_unit;
  	sc->lpt_dev.name = lptdriver.name;
  	sc->lpt_dev.ppb = ppb;
  	sc->lpt_dev.intr = lptintr;
  
  	/*
  	 * Now, try to detect the printer.
  	 */
  	if (!lpt_detect(sc)) {
  		free(sc, M_TEMP);
  		return (0);
  	}
  
  	/* Ok, go to next device on next probe */
  	nlpt ++;
  
  	return (&sc->lpt_dev);
  }
  
  static int
  lptattach(struct ppb_device *dev)
  {
  	struct lpt_data *sc = lptdata[dev->id_unit];
  	int error;
  
  	/*
  	 * Report ourselves
  	 */
  	printf(LPT_NAME "%d: <generic printer> on ppbus %d\n",
  	       dev->id_unit, dev->ppb->ppb_link->adapter_unit);
  
  	sc->sc_primed = 0;	/* not primed yet */
  
  	if ((error = lpt_request_ppbus(sc, PPB_DONTWAIT))) {
  		printf(LPT_NAME ": cannot alloc ppbus (%d)!\n", error);
  		return (0);
  	}
  
  	ppb_wctr(&sc->lpt_dev, LPC_NINIT);
  
  	/* check if we can use interrupt, should be done by ppc stuff */
  	lprintf(("oldirq %x\n", sc->sc_irq));
  	if (ppb_get_irq(&sc->lpt_dev)) {
  		sc->sc_irq = LP_HAS_IRQ | LP_USE_IRQ | LP_ENABLE_IRQ;
  		printf(LPT_NAME "%d: Interrupt-driven port\n", dev->id_unit);
  	} else {
  		sc->sc_irq = 0;
  		lprintf((LPT_NAME "%d: Polled port\n", dev->id_unit));
  	}
  	lprintf(("irq %x\n", sc->sc_irq));
  
  	lpt_release_ppbus(sc);
  
  #ifdef DEVFS
  	sc->devfs_token = devfs_add_devswf(&lpt_cdevsw,
  		dev->id_unit, DV_CHR,
  		UID_ROOT, GID_WHEEL, 0600, LPT_NAME "%d", dev->id_unit);
  	sc->devfs_token_ctl = devfs_add_devswf(&lpt_cdevsw,
  		dev->id_unit | LP_BYPASS, DV_CHR,
  		UID_ROOT, GID_WHEEL, 0600, LPT_NAME "%d.ctl", dev->id_unit);
  #endif
  
  	return (1);
  }
  
  static void
  lptout(void *arg)
  {
  	struct lpt_data *sc = arg;
  	int pl;
  
  	lprintf(("T %x ", ppb_rstr(&sc->lpt_dev)));
  	if (sc->sc_state & OPEN) {
  		sc->sc_backoff++;
  		if (sc->sc_backoff > hz/LPTOUTMAX)
  			sc->sc_backoff = sc->sc_backoff > hz/LPTOUTMAX;
  		timeout(lptout, (caddr_t)sc, sc->sc_backoff);
  	} else
  		sc->sc_state &= ~TOUT;
  
  	if (sc->sc_state & EERROR)
  		sc->sc_state &= ~EERROR;
  
  	/*
  	 * Avoid possible hangs do to missed interrupts
  	 */
  	if (sc->sc_xfercnt) {
  		pl = spltty();
  		lpt_intr(sc->lpt_unit);
  		splx(pl);
  	} else {
  		sc->sc_state &= ~OBUSY;
  		wakeup((caddr_t)sc);
  	}
  }
  
  /*
   * lptopen -- reset the printer, then wait until it's selected and not busy.
   *	If LP_BYPASS flag is selected, then we do not try to select the
   *	printer -- this is just used for passing ioctls.
   */
  
  static	int
  lptopen(dev_t dev, int flags, int fmt, struct proc *p)
  {
  	struct lpt_data *sc;
  
  	int s;
  	int trys, err;
  	u_int unit = LPTUNIT(minor(dev));
  
  	if ((unit >= nlpt))
  		return (ENXIO);
  
  	sc = lptdata[unit];
  
  	if (sc->sc_state) {
  		lprintf((LPT_NAME ": still open %x\n", sc->sc_state));
  		return(EBUSY);
  	} else
  		sc->sc_state |= LPTINIT;
  
  	sc->sc_flags = LPTFLAGS(minor(dev));
  
  	/* Check for open with BYPASS flag set. */
  	if (sc->sc_flags & LP_BYPASS) {
  		sc->sc_state = OPEN;
  		return(0);
  	}
  
  	/* request the ppbus only if we don't have it already */
  	if ((err = lpt_request_ppbus(sc, PPB_WAIT|PPB_INTR)) != 0)
  		return (err);
  
  	s = spltty();
  	lprintf((LPT_NAME " flags 0x%x\n", sc->sc_flags));
  
  	/* set IRQ status according to ENABLE_IRQ flag */
  	if (sc->sc_irq & LP_ENABLE_IRQ)
  		sc->sc_irq |= LP_USE_IRQ;
  	else
  		sc->sc_irq &= ~LP_USE_IRQ;
  
  	/* init printer */
  	if ((sc->sc_flags & LP_NO_PRIME) == 0) {
  		if((sc->sc_flags & LP_PRIMEOPEN) || sc->sc_primed == 0) {
  			ppb_wctr(&sc->lpt_dev, 0);
  			sc->sc_primed++;
  			DELAY(500);
  		}
  	}
  
  	ppb_wctr(&sc->lpt_dev, LPC_SEL|LPC_NINIT);
  
  	/* wait till ready (printer running diagnostics) */
  	trys = 0;
  	do {
  		/* ran out of waiting for the printer */
  		if (trys++ >= LPINITRDY*4) {
  			splx(s);
  			sc->sc_state = 0;
  			lprintf(("status %x\n", ppb_rstr(&sc->lpt_dev)));
  
  			lpt_release_ppbus(sc);
  			return (EBUSY);
  		}
  
  		/* wait 1/4 second, give up if we get a signal */
  		if (tsleep((caddr_t)sc, LPPRI|PCATCH, "lptinit", hz/4) !=
  		    EWOULDBLOCK) {
  			sc->sc_state = 0;
  			splx(s);
  
  			lpt_release_ppbus(sc);
  			return (EBUSY);
  		}
  
  		/* is printer online and ready for output */
  	} while ((ppb_rstr(&sc->lpt_dev) &
  			(LPS_SEL|LPS_OUT|LPS_NBSY|LPS_NERR)) !=
  					(LPS_SEL|LPS_NBSY|LPS_NERR));
  
  	sc->sc_control = LPC_SEL|LPC_NINIT;
  	if (sc->sc_flags & LP_AUTOLF)
  		sc->sc_control |= LPC_AUTOL;
  
  	/* enable interrupt if interrupt-driven */
  	if (sc->sc_irq & LP_USE_IRQ)
  		sc->sc_control |= LPC_ENA;
  
  	ppb_wctr(&sc->lpt_dev, sc->sc_control);
  
  	sc->sc_state = OPEN;
  	sc->sc_inbuf = geteblk(BUFSIZE);
  	sc->sc_statbuf = geteblk(BUFSTATSIZE);
  	sc->sc_xfercnt = 0;
  	splx(s);
  
  	/* release the ppbus */
  	lpt_release_ppbus(sc);
  
  	/* only use timeout if using interrupt */
  	lprintf(("irq %x\n", sc->sc_irq));
  	if (sc->sc_irq & LP_USE_IRQ) {
  		sc->sc_state |= TOUT;
  		timeout(lptout, (caddr_t)sc,
  			 (sc->sc_backoff = hz/LPTOUTINITIAL));
  	}
  
  	lprintf(("opened.\n"));
  	return(0);
  }
  
  /*
   * lptclose -- close the device, free the local line buffer.
   *
   * Check for interrupted write call added.
   */
  
  static	int
  lptclose(dev_t dev, int flags, int fmt, struct proc *p)
  {
  	struct lpt_data *sc = lptdata[LPTUNIT(minor(dev))];
  	int err;
  
  	if(sc->sc_flags & LP_BYPASS)
  		goto end_close;
  
  	if ((err = lpt_request_ppbus(sc, PPB_WAIT|PPB_INTR)) != 0)
  		return (err);
  
  	sc->sc_state &= ~OPEN;
  
  	/* if the last write was interrupted, don't complete it */
  	if((!(sc->sc_state  & INTERRUPTED)) && (sc->sc_irq & LP_USE_IRQ))
  		while ((ppb_rstr(&sc->lpt_dev) &
  			(LPS_SEL|LPS_OUT|LPS_NBSY|LPS_NERR)) !=
  			(LPS_SEL|LPS_NBSY|LPS_NERR) || sc->sc_xfercnt)
  			/* wait 1/4 second, give up if we get a signal */
  			if (tsleep((caddr_t)sc, LPPRI|PCATCH,
  				"lpclose", hz) != EWOULDBLOCK)
  				break;
  
  	ppb_wctr(&sc->lpt_dev, LPC_NINIT);
  	brelse(sc->sc_inbuf);
  	brelse(sc->sc_statbuf);
  
  end_close:
  	/* release the bus anyway */
  	lpt_release_ppbus(sc);
  
  	sc->sc_state = 0;
  	sc->sc_xfercnt = 0;
  	lprintf(("closed.\n"));
  	return(0);
  }
  
  /*
   * lpt_pushbytes()
   *	Workhorse for actually spinning and writing bytes to printer
   *	Derived from lpa.c
   *	Originally by ?
   *
   *	This code is only used when we are polling the port
   */
  static int
  lpt_pushbytes(struct lpt_data *sc)
  {
  	int spin, err, tic;
  	char ch;
  
  	lprintf(("p"));
  	/* loop for every character .. */
  	while (sc->sc_xfercnt > 0) {
  		/* printer data */
  		ch = *(sc->sc_cp);
  		sc->sc_cp++;
  		sc->sc_xfercnt--;
  
  		/*
  		 * Wait for printer ready.
  		 * Loop 20 usecs testing BUSY bit, then sleep
  		 * for exponentially increasing timeout. (vak)
  		 */
  		for (spin = 0; NOT_READY(sc) && spin < MAX_SPIN; ++spin)
  			DELAY(1);	/* XXX delay is NOT this accurate! */
  		if (spin >= MAX_SPIN) {
  			tic = 0;
  			while (NOT_READY(sc)) {
  				/*
  				 * Now sleep, every cycle a
  				 * little longer ..
  				 */
  				tic = tic + tic + 1;
  				/*
  				 * But no more than 10 seconds. (vak)
  				 */
  				if (tic > MAX_SLEEP)
  					tic = MAX_SLEEP;
  				err = tsleep((caddr_t)sc, LPPRI,
  					LPT_NAME "poll", tic);
  				if (err != EWOULDBLOCK) {
  					return (err);
  				}
  			}
  		}
  
  		/* output data */
  		ppb_wdtr(&sc->lpt_dev, ch);
  		/* strobe */
  		ppb_wctr(&sc->lpt_dev, sc->sc_control|LPC_STB);
  		ppb_wctr(&sc->lpt_dev, sc->sc_control);
  
  	}
  	return(0);
  }
  
  /*
   * lptread --retrieve printer status in IEEE1284 NIBBLE mode
   */
  
  static int
  lptread(dev_t dev, struct uio *uio, int ioflag)
  {
  	struct lpt_data *sc = lptdata[LPTUNIT(minor(dev))];
  	int error = 0, len;
  
  	if ((error = ppb_1284_negociate(&sc->lpt_dev, PPB_NIBBLE, 0)))
  		return (error);
  
  	/* read data in an other buffer, read/write may be simultaneous */
  	len = 0;
  	while (uio->uio_resid) {
  		if ((error = ppb_1284_read(&sc->lpt_dev, PPB_NIBBLE,
  				sc->sc_statbuf->b_data, min(BUFSTATSIZE,
  				uio->uio_resid), &len))) {
  			goto error;
  		}
  
  		if (!len)
  			goto error;		/* no more data */
  
  		if ((error = uiomove(sc->sc_statbuf->b_data, len, uio)))
  			goto error;
  	}
  
  error:
  	ppb_1284_terminate(&sc->lpt_dev);
  	return (error);
  }
  
  /*
   * lptwrite --copy a line from user space to a local buffer, then call
   * putc to get the chars moved to the output queue.
   *
   * Flagging of interrupted write added.
   */
  
  static	int
  lptwrite(dev_t dev, struct uio *uio, int ioflag)
  {
  	register unsigned n;
  	int pl, err;
          u_int	unit = LPTUNIT(minor(dev));
  	struct lpt_data *sc = lptdata[LPTUNIT(minor(dev))];
  
  	if(sc->sc_flags & LP_BYPASS) {
  		/* we can't do writes in bypass mode */
  		return(EPERM);
  	}
  
  	/* request the ppbus only if we don't have it already */
  	if ((err = lpt_request_ppbus(sc, PPB_WAIT|PPB_INTR)) != 0)
  		return (err);
  
  	sc->sc_state &= ~INTERRUPTED;
  	while ((n = min(BUFSIZE, uio->uio_resid)) != 0) {
  		sc->sc_cp = sc->sc_inbuf->b_data ;
  		uiomove(sc->sc_cp, n, uio);
  		sc->sc_xfercnt = n ;
  
  		if (sc->sc_irq & LP_ENABLE_EXT) {
  			/* try any extended mode */
  			err = ppb_write(&sc->lpt_dev, sc->sc_cp,
  							sc->sc_xfercnt, 0);
  			switch (err) {
  			case 0:
  				/* if not all data was sent, we could rely
  				 * on polling for the last bytes */
  				sc->sc_xfercnt = 0;
  				break;
  			case EINTR:
  				sc->sc_state |= INTERRUPTED;	
  				return(err);
  			case EINVAL:
  				/* advanced mode not avail */
  				log(LOG_NOTICE, LPT_NAME "%d: advanced mode not avail, polling\n", unit);
  				break;
  			default:
  				return(err);
  			}
  		} else while ((sc->sc_xfercnt > 0)&&(sc->sc_irq & LP_USE_IRQ)) {
  			lprintf(("i"));
  			/* if the printer is ready for a char, */
  			/* give it one */
  			if ((sc->sc_state & OBUSY) == 0){
  				lprintf(("\nC %d. ", sc->sc_xfercnt));
  				pl = spltty();
  				lpt_intr(sc->lpt_unit);
  				(void) splx(pl);
  			}
  			lprintf(("W "));
  			if (sc->sc_state & OBUSY)
  				if ((err = tsleep((caddr_t)sc,
  					 LPPRI|PCATCH, LPT_NAME "write", 0))) {
  					sc->sc_state |= INTERRUPTED;
  					return(err);
  				}
  		}
  
  		/* check to see if we must do a polled write */
  		if(!(sc->sc_irq & LP_USE_IRQ) && (sc->sc_xfercnt)) {
  			lprintf(("p"));
  
  			err = lpt_pushbytes(sc);
  
  			if (err)
  				return(err);
  		}
  	}
  
  	/* we have not been interrupted, release the ppbus */
  	lpt_release_ppbus(sc);
  
  	return(0);
  }
  
  /*
   * lpt_intr -- handle printer interrupts which occur when the printer is
   * ready to accept another char.
   *
   * do checking for interrupted write call.
   */
  
  static void
  lpt_intr(int unit)
  {
  	struct lpt_data *sc = lptdata[unit];
  	int sts;
  	int i;
  	
  	/* we must own the bus to use it */
  	if ((sc->sc_state & HAVEBUS) == 0)
  		return;
  
  	/*
  	 * Is printer online and ready for output?
  	 *
  	 * Avoid falling back to lptout() too quickly.  First spin-loop
  	 * to see if the printer will become ready ``really soon now''.
  	 */
  	for (i = 0; i < 100 &&
  	     ((sts=ppb_rstr(&sc->lpt_dev)) & RDY_MASK) != LP_READY; i++) ;
  
  	if ((sts & RDY_MASK) == LP_READY) {
  		sc->sc_state = (sc->sc_state | OBUSY) & ~EERROR;
  		sc->sc_backoff = hz/LPTOUTINITIAL;
  
  		if (sc->sc_xfercnt) {
  			/* send char */
  			/*lprintf(("%x ", *sc->sc_cp)); */
  			ppb_wdtr(&sc->lpt_dev, *sc->sc_cp++) ;
  			ppb_wctr(&sc->lpt_dev, sc->sc_control|LPC_STB);
  			/* DELAY(X) */
  			ppb_wctr(&sc->lpt_dev, sc->sc_control);
  
  			/* any more data for printer */
  			if(--(sc->sc_xfercnt) > 0) return;
  		}
  
  		/*
  		 * No more data waiting for printer.
  		 * Wakeup is not done if write call was interrupted.
  		 */
  		sc->sc_state &= ~OBUSY;
  
  		if(!(sc->sc_state & INTERRUPTED))
  			wakeup((caddr_t)sc);
  		lprintf(("w "));
  		return;
  	} else	{	/* check for error */
  		if(((sts & (LPS_NERR | LPS_OUT) ) != LPS_NERR) &&
  				(sc->sc_state & OPEN))
  			sc->sc_state |= EERROR;
  		/* lptout() will jump in and try to restart. */
  	}
  	lprintf(("sts %x ", sts));
  }
  
  static void
  lptintr(int unit)
  {
  	/* call the interrupt at required spl level */
  	int s = spltty();
  
  	lpt_intr(unit);
  
  	splx(s);
  	return;
  }
  
  static	int
  lptioctl(dev_t dev, u_long cmd, caddr_t data, int flags, struct proc *p)
  {
  	int	error = 0;
          struct	lpt_data *sc;
          u_int	unit = LPTUNIT(minor(dev));
  	u_char	old_sc_irq;	/* old printer IRQ status */
  
          sc = lptdata[unit];
  
  	switch (cmd) {
  	case LPT_IRQ :
  		if(sc->sc_irq & LP_HAS_IRQ) {
  			/*
  			 * NOTE:
  			 * If the IRQ status is changed,
  			 * this will only be visible on the
  			 * next open.
  			 *
  			 * If interrupt status changes,
  			 * this gets syslog'd.
  			 */
  			old_sc_irq = sc->sc_irq;
  			switch(*(int*)data) {
  			case 0:
  				sc->sc_irq &= (~LP_ENABLE_IRQ);
  				break;
  			case 1:
  				sc->sc_irq &= (~LP_ENABLE_EXT);
  				sc->sc_irq |= LP_ENABLE_IRQ;
  				break;
  			case 2:
  				/* classic irq based transfer and advanced
  				 * modes are in conflict
  				 */
  				sc->sc_irq &= (~LP_ENABLE_IRQ);
  				sc->sc_irq |= LP_ENABLE_EXT;
  				break;
  			case 3:
  				sc->sc_irq &= (~LP_ENABLE_EXT);
  				break;
  			default:
  				break;
  			}
  				
  			if (old_sc_irq != sc->sc_irq )
  				log(LOG_NOTICE, LPT_NAME "%d: switched to %s %s mode\n",
  					unit,
  					(sc->sc_irq & LP_ENABLE_IRQ)?
  					"interrupt-driven":"polled",
  					(sc->sc_irq & LP_ENABLE_EXT)?
  					"extended":"standard");
  		} else /* polled port */
  			error = EOPNOTSUPP;
  		break;
  	default:
  		error = ENODEV;
  	}
  
  	return(error);
  }
  
  static lpt_devsw_installed = 0;
  
  static void
  lpt_drvinit(void *unused)
  {
  	dev_t dev;
  
  	if( ! lpt_devsw_installed ) {
  		dev = makedev(CDEV_MAJOR, 0);
  		cdevsw_add(&dev,&lpt_cdevsw, NULL);
  		lpt_devsw_installed = 1;
      	}
  }
  
  SYSINIT(lptdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,lpt_drvinit,NULL)
  