bridge(4): document net.link.bridge.pfil_onlyip

[dragonfly.git] / sys / dev / misc / lpt / lpt.c

/*
 * 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
 * $FreeBSD: src/sys/dev/ppbus/lpt.c,v 1.15.2.3 2000/07/07 00:30:40 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]
 */

#include "opt_lpt.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/module.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/device.h>
#include <sys/kernel.h>
#include <sys/uio.h>
#include <sys/syslog.h>
#include <sys/thread2.h>
#include <sys/malloc.h>
#include <sys/rman.h>

#include <machine/clock.h>
#include <machine/inttypes.h>

#include "lptio.h"
#include <bus/ppbus/ppbconf.h>
#include <bus/ppbus/ppb_1284.h>
#include "lpt.h"
#include "ppbus_if.h"
#include <bus/ppbus/ppbio.h>

MALLOC_DEFINE(M_LPT, "lpt", "LPT buffers");

#ifndef LPT_DEBUG
#define lprintf(args)
#else
#define lprintf(args)                                           \
                do {                                            \
                        if (lptflag)                            \
                                kprintf 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 BUFSIZE         1024
#define BUFSTATSIZE     32

#define LPTUNIT(s)      ((s)&0x03)
#define LPTFLAGS(s)     ((s)&0xfc)

struct lpt_data {
        short   sc_state;
        /* default case: negative prime, negative ack, handshake strobe,
           prime once */
        u_char  sc_control;
        char    sc_flags;
#define LP_UNITMASK     0x03    /* up to 4 units */
#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 */
        void    *sc_inbuf;
        void    *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 */

        struct resource *intr_resource; /* interrupt resource */
        void *intr_cookie;              /* interrupt registration cookie */
        struct callout  sc_callout;
};

#define LPT_NAME        "lpt"           /* our official name */

static timeout_t lptout;
static int      lpt_port_test(device_t dev, u_char data, u_char mask);
static int      lpt_detect(device_t dev);

#define DEVTOSOFTC(dev) \
        ((struct lpt_data *)device_get_softc(dev))
#define UNITOSOFTC(unit) \
        ((struct lpt_data *)devclass_get_softc(lpt_devclass, (unit)))
#define UNITODEVICE(unit) \
        (devclass_get_device(lpt_devclass, (unit)))

static void lptintr(device_t dev);
static void lpt_intr(void *arg);        /* without spls */

static devclass_t lpt_devclass;


/* 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(ppbus) ((ppb_rstr(ppbus)^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;

static struct dev_ops lpt_ops = {
        { LPT_NAME, 0, 0 },
        .d_open =       lptopen,
        .d_close =      lptclose,
        .d_read =       lptread,
        .d_write =      lptwrite,
        .d_ioctl =      lptioctl,
};

static int
lpt_request_ppbus(device_t dev, int how)
{
        device_t ppbus = device_get_parent(dev);
        struct lpt_data *sc = DEVTOSOFTC(dev);
        int error;

        if (sc->sc_state & HAVEBUS)
                return (0);

        /* we have the bus only if the request succeeded */
        if ((error = ppb_request_bus(ppbus, dev, how)) == 0)
                sc->sc_state |= HAVEBUS;

        return (error);
}

static int
lpt_release_ppbus(device_t dev)
{
        device_t ppbus = device_get_parent(dev);
        struct lpt_data *sc = DEVTOSOFTC(dev);
        int error = 0;

        if ((error = ppb_release_bus(ppbus, dev)) == 0)
                sc->sc_state &= ~HAVEBUS;

        return (error);
}

/*
 * Internal routine to lptprobe to do port tests of one byte value
 */
static int
lpt_port_test(device_t ppbus, u_char data, u_char mask)
{
        int     temp, timeout;

        data = data & mask;
        ppb_wdtr(ppbus, data);
        timeout = 10000;
        do {
                DELAY(10);
                temp = ppb_rdtr(ppbus) & 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(device_t dev)
{
        device_t ppbus = device_get_parent(dev);

        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(dev, PPB_DONTWAIT))) {
                kprintf(LPT_NAME ": cannot alloc ppbus (%d)!\n", error);
                status = 0;
                goto end_probe;
        }

        for (i = 0; i < 18 && status; i++)
                if (!lpt_port_test(ppbus, testbyte[i], 0xff)) {
                        status = 0;
                        goto end_probe;
                }

end_probe:
        /* write 0's to control and data ports */
        ppb_wdtr(ppbus, 0);
        ppb_wctr(ppbus, 0);

        lpt_release_ppbus(dev);

        return (status);
}

/*
 * lpt_probe()
 */
static int
lpt_probe(device_t dev)
{
        struct lpt_data *sc;

        sc = DEVTOSOFTC(dev);
        bzero(sc, sizeof(struct lpt_data));

        /*
         * Now, try to detect the printer.
         */
        if (!lpt_detect(dev))
                return (ENXIO);

        device_set_desc(dev, "Printer");

        return (0);
}

static int
lpt_attach(device_t dev)
{
        device_t ppbus = device_get_parent(dev);
        struct lpt_data *sc = DEVTOSOFTC(dev);
        int zero = 0, unit = device_get_unit(dev);
        int error;
        uintptr_t irq;

        sc->sc_primed = 0;      /* not primed yet */
        callout_init(&sc->sc_callout);

        if ((error = lpt_request_ppbus(dev, PPB_DONTWAIT))) {
                kprintf(LPT_NAME ": cannot alloc ppbus (%d)!\n", error);
                return (0);
        }

        ppb_wctr(ppbus, LPC_NINIT);

        /* check if we can use interrupt, should be done by ppc stuff */
        lprintf(("oldirq %x\n", sc->sc_irq));

        /* retrieve the ppbus irq */
        BUS_READ_IVAR(ppbus, dev, PPBUS_IVAR_IRQ, &irq);

        if (irq > 0) {
                /* declare our interrupt handler */
                sc->intr_resource = bus_alloc_legacy_irq_resource(dev, &zero,
                    irq, RF_SHAREABLE);
        }
        if (sc->intr_resource) {
                sc->sc_irq = LP_HAS_IRQ | LP_USE_IRQ | LP_ENABLE_IRQ;
                device_printf(dev, "Interrupt-driven port\n");
        } else {
                sc->sc_irq = 0;
                device_printf(dev, "Polled port\n");
        }
        lprintf(("irq %"PRIxPTR" %x\n", irq, sc->sc_irq));

        lpt_release_ppbus(dev);

        make_dev(&lpt_ops, unit, UID_ROOT, GID_WHEEL,
                 0600, LPT_NAME "%d", unit);
        make_dev(&lpt_ops, unit | LP_BYPASS, UID_ROOT, GID_WHEEL,
                 0600, LPT_NAME "%d.ctl", unit);
        return (0);
}

static void
lptout(void *arg)
{
        device_t dev = (device_t)arg;
        struct lpt_data *sc = DEVTOSOFTC(dev);
#ifdef LPT_DEBUG
        device_t ppbus = device_get_parent(dev);
#endif

        lprintf(("T %x ", ppb_rstr(ppbus)));
        if (sc->sc_state & OPEN) {
                sc->sc_backoff++;
                if (sc->sc_backoff > hz/LPTOUTMAX)
                        sc->sc_backoff = sc->sc_backoff > hz/LPTOUTMAX;
                callout_reset(&sc->sc_callout, sc->sc_backoff, lptout, dev);
        } else {
                sc->sc_state &= ~TOUT;
        }

        if (sc->sc_state & EERROR)
                sc->sc_state &= ~EERROR;

        /*
         * Avoid possible hangs due to missed interrupts
         */
        if (sc->sc_xfercnt) {
                lptintr(dev);
        } else {
                sc->sc_state &= ~OBUSY;
                wakeup((caddr_t)dev);
        }
}

/*
 * 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(struct dev_open_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        int trys, err;
        u_int unit = LPTUNIT(minor(dev));
        struct lpt_data *sc = UNITOSOFTC(unit);
        device_t lptdev = UNITODEVICE(unit);
        device_t ppbus = device_get_parent(lptdev);

        if (!sc)
                return (ENXIO);

        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(lptdev, PPB_WAIT|PPB_INTR)) != 0) {
                /* give it a chance to try later */
                sc->sc_state = 0;
                return (err);
        }

        crit_enter();
        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(ppbus, 0);
                        sc->sc_primed++;
                        DELAY(500);
                }
        }

        ppb_wctr(ppbus, LPC_SEL|LPC_NINIT);

        /* wait till ready (printer running diagnostics) */
        trys = 0;
        do {
                /* ran out of waiting for the printer */
                if (trys++ >= LPINITRDY*4) {
                        crit_exit();
                        sc->sc_state = 0;
                        lprintf(("status %x\n", ppb_rstr(ppbus)));

                        lpt_release_ppbus(lptdev);
                        return (EBUSY);
                }

                /* wait 1/4 second, give up if we get a signal */
                if (tsleep((caddr_t)lptdev, PCATCH, "lptinit", hz/4) !=
                    EWOULDBLOCK) {
                        sc->sc_state = 0;
                        crit_exit();

                        lpt_release_ppbus(lptdev);
                        return (EBUSY);
                }

                /* is printer online and ready for output */
        } while ((ppb_rstr(ppbus) &
                        (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(ppbus, sc->sc_control);

        sc->sc_state = OPEN;
        sc->sc_inbuf = kmalloc(BUFSIZE, M_LPT, M_WAITOK);
        sc->sc_statbuf = kmalloc(BUFSTATSIZE, M_LPT, M_WAITOK);
        sc->sc_xfercnt = 0;

        crit_exit();

        /* release the ppbus */
        lpt_release_ppbus(lptdev);

        /* only use timeout if using interrupt */
        lprintf(("irq %x\n", sc->sc_irq));
        if (sc->sc_irq & LP_USE_IRQ) {
                sc->sc_state |= TOUT;
                sc->sc_backoff = hz / LPTOUTINITIAL;
                callout_reset(&sc->sc_callout, sc->sc_backoff, lptout, lptdev);
        }

        lprintf(("opened.\n"));
        return(0);
}

/*
 * lptclose -- close the device, free the local line buffer.
 *
 * Check for interrupted write call added.
 */

static  int
lptclose(struct dev_close_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        u_int unit = LPTUNIT(minor(dev));
        struct lpt_data *sc = UNITOSOFTC(unit);
        device_t lptdev = UNITODEVICE(unit);
        device_t ppbus = device_get_parent(lptdev);
        int err;

        if(sc->sc_flags & LP_BYPASS)
                goto end_close;

        if ((err = lpt_request_ppbus(lptdev, 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(ppbus) &
                    (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)lptdev, PCATCH,
                            "lpclose", hz) != EWOULDBLOCK) {
                                break;
                        }
                }
        }
        callout_stop(&sc->sc_callout);
        ppb_wctr(ppbus, LPC_NINIT);
        kfree(sc->sc_inbuf, M_LPT);
        kfree(sc->sc_statbuf, M_LPT);

end_close:
        /* release the bus anyway
         * unregistration of interrupt forced by release
         */
        lpt_release_ppbus(lptdev);

        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(device_t dev)
{
        struct lpt_data *sc = DEVTOSOFTC(dev);
        device_t ppbus = device_get_parent(dev);
        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(ppbus) && spin < MAX_SPIN; ++spin)
                        DELAY(1);       /* XXX delay is NOT this accurate! */
                if (spin >= MAX_SPIN) {
                        tic = 0;
                        while (NOT_READY(ppbus)) {
                                /*
                                 * 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)dev, 0,
                                        LPT_NAME "poll", tic);
                                if (err != EWOULDBLOCK) {
                                        return (err);
                                }
                        }
                }

                /* output data */
                ppb_wdtr(ppbus, ch);
                /* strobe */
                ppb_wctr(ppbus, sc->sc_control|LPC_STB);
                ppb_wctr(ppbus, sc->sc_control);

        }
        return(0);
}

/*
 * lptread --retrieve printer status in IEEE1284 NIBBLE mode
 */

static int
lptread(struct dev_read_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        struct uio *uio = ap->a_uio;
        u_int   unit = LPTUNIT(minor(dev));
        struct lpt_data *sc = UNITOSOFTC(unit);
        device_t lptdev = UNITODEVICE(unit);
        device_t ppbus = device_get_parent(lptdev);
        int error = 0, len;

        if (sc->sc_flags & LP_BYPASS) {
                /* we can't do reads in bypass mode */
                return (EPERM);
        }

        if ((error = ppb_1284_negotiate(ppbus, PPB_NIBBLE, 0)))
                return (error);

        /* read data in an other buffer, read/write may be simultaneous */
        len = 0;
        while (uio->uio_resid) {
                error = ppb_1284_read(ppbus, PPB_NIBBLE, sc->sc_statbuf,
                                      (int)szmin(BUFSTATSIZE, uio->uio_resid),
                                      &len);
                if (error)
                        goto error;

                if (!len)
                        goto error;             /* no more data */

                if ((error = uiomove(sc->sc_statbuf, (size_t)len, uio)))
                        goto error;
        }

error:
        ppb_1284_terminate(ppbus);
        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(struct dev_write_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        struct uio *uio = ap->a_uio;
        unsigned n;
        int err;
        u_int   unit = LPTUNIT(minor(dev));
        struct lpt_data *sc = UNITOSOFTC(unit);
        device_t lptdev = UNITODEVICE(unit);
        device_t ppbus = device_get_parent(lptdev);

        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 */
        /* XXX interrupt registration?! */
        if ((err = lpt_request_ppbus(lptdev, PPB_WAIT|PPB_INTR)) != 0)
                return (err);

        /* if interrupts are working, register the handler */
        if (sc->sc_irq & LP_USE_IRQ) {
                /* register our interrupt handler */
                err = BUS_SETUP_INTR(ppbus, lptdev, sc->intr_resource,
                               0, lpt_intr, lptdev,
                               &sc->intr_cookie, NULL, NULL);
                if (err) {
                        device_printf(lptdev, "handler registration failed, polled mode.\n");
                        sc->sc_irq &= ~LP_USE_IRQ;
                }
        }

        sc->sc_state &= ~INTERRUPTED;
        while ((n = (unsigned)szmin(BUFSIZE, uio->uio_resid)) != 0) {
                sc->sc_cp = sc->sc_inbuf;
                uiomove(sc->sc_cp, (size_t)n, uio);
                sc->sc_xfercnt = n;

                if (sc->sc_irq & LP_ENABLE_EXT) {
                        /* try any extended mode */
                        err = ppb_write(ppbus, 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));
                                lptintr(lptdev);
                        }
                        lprintf(("W "));
                        if (sc->sc_state & OBUSY)
                                if ((err = tsleep((caddr_t)lptdev,
                                         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(lptdev);

                        if (err)
                                return (err);
                }
        }

        /* we have not been interrupted, release the ppbus */
        lpt_release_ppbus(lptdev);

        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(void *arg)
{
        device_t lptdev = (device_t)arg;
        device_t ppbus = device_get_parent(lptdev);
        struct lpt_data *sc = DEVTOSOFTC(lptdev);
        int sts = 0;
        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(ppbus)) & 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(ppbus, *sc->sc_cp++) ;
                        ppb_wctr(ppbus, sc->sc_control|LPC_STB);
                        /* DELAY(X) */
                        ppb_wctr(ppbus, 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 not interrupted.
                 */
                sc->sc_state &= ~OBUSY;

                if (!(sc->sc_state & INTERRUPTED))
                        wakeup((caddr_t)lptdev);
                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(device_t dev)
{
        /* call the interrupt at required spl level */
        crit_enter();

        lpt_intr(dev);

        crit_exit();
}

static  int
lptioctl(struct dev_ioctl_args *ap)
{
        cdev_t dev = ap->a_head.a_dev;
        int     error = 0;
        u_int   unit = LPTUNIT(minor(dev));
        struct  lpt_data *sc = UNITOSOFTC(unit);
        u_char  old_sc_irq;     /* old printer IRQ status */

        switch (ap->a_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*)ap->a_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);
}

/*
 * Because lpt is a static device that always exists under a ppbus device,
 * and not scanned by the ppbus device, we need an identify function to
 * install its device.
 */
static device_method_t lpt_methods[] = {
        /* device interface */
        DEVMETHOD(device_identify,      bus_generic_identify),
        DEVMETHOD(device_probe,         lpt_probe),
        DEVMETHOD(device_attach,        lpt_attach),

        DEVMETHOD_END
};

static driver_t lpt_driver = {
        LPT_NAME,
        lpt_methods,
        sizeof(struct lpt_data),
};

DRIVER_MODULE(lpt, ppbus, lpt_driver, lpt_devclass, NULL, NULL);