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mms.c revision 1.6.2.2
      1      1.1   andrew /*-
      2  1.6.2.1  mycroft  * Copyright (c) 1993 Charles Hannum
      3      1.1   andrew  * Copyright (c) 1992, 1993 Erik Forsberg.
      4      1.1   andrew  * All rights reserved.
      5      1.1   andrew  *
      6      1.1   andrew  * Redistribution and use in source and binary forms, with or without
      7      1.1   andrew  * modification, are permitted provided that the following conditions
      8      1.1   andrew  * are met:
      9      1.1   andrew  * 1. Redistributions of source code must retain the above copyright
     10      1.1   andrew  *    notice, this list of conditions and the following disclaimer.
     11      1.1   andrew  *
     12      1.1   andrew  * THIS SOFTWARE IS PROVIDED BY ``AS IS'' AND ANY EXPRESS OR IMPLIED
     13      1.1   andrew  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     14      1.1   andrew  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
     15      1.1   andrew  * NO EVENT SHALL I BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     16      1.1   andrew  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     17      1.1   andrew  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     18      1.1   andrew  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
     19      1.1   andrew  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
     20      1.1   andrew  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     21      1.1   andrew  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     22      1.1   andrew  *
     23  1.6.2.2  mycroft  *	$Id: mms.c,v 1.6.2.2 1993/09/30 17:33:03 mycroft Exp $
     24      1.1   andrew  */
     25      1.1   andrew 
     26      1.1   andrew #include "param.h"
     27      1.1   andrew #include "kernel.h"
     28      1.1   andrew #include "systm.h"
     29      1.1   andrew #include "buf.h"
     30      1.1   andrew #include "malloc.h"
     31      1.1   andrew #include "ioctl.h"
     32      1.1   andrew #include "tty.h"
     33      1.1   andrew #include "file.h"
     34      1.1   andrew #include "select.h"
     35      1.1   andrew #include "proc.h"
     36      1.1   andrew #include "vnode.h"
     37  1.6.2.1  mycroft #include "sys/device.h"
     38      1.1   andrew 
     39  1.6.2.1  mycroft #include "i386/isa/isavar.h"
     40      1.1   andrew #include "i386/include/mouse.h"
     41  1.6.2.1  mycroft #include "i386/include/pio.h"
     42      1.1   andrew 
     43  1.6.2.1  mycroft #define MMS_ADDR	0	/* Offset for register select */
     44  1.6.2.1  mycroft #define MMS_DATA	1	/* Offset for InPort data */
     45  1.6.2.1  mycroft #define MMS_IDENT	2	/* Offset for identification register */
     46  1.6.2.1  mycroft #define	MMS_NPORTS	4
     47  1.6.2.1  mycroft 
     48  1.6.2.1  mycroft #define	MMS_CHUNK	128	/* chunk size for read */
     49  1.6.2.1  mycroft #define	MMS_BSIZE	1024	/* buffer size */
     50  1.6.2.1  mycroft 
     51  1.6.2.1  mycroft struct mms_softc {		/* Driver status information */
     52  1.6.2.2  mycroft 	struct	device sc_dev;
     53  1.6.2.2  mycroft 	struct	isadev sc_id;
     54  1.6.2.2  mycroft 	struct	intrhand sc_ih;
     55  1.6.2.2  mycroft 
     56  1.6.2.2  mycroft 	struct	ringbuf {	/* Input queue */
     57  1.6.2.1  mycroft 		int rb_count, rb_first, rb_last;
     58  1.6.2.1  mycroft 		char rb_data[MMS_BSIZE];
     59  1.6.2.1  mycroft 	} sc_q;
     60  1.6.2.1  mycroft 	struct	selinfo sc_rsel;
     61  1.6.2.1  mycroft 	u_short	sc_iobase;	/* I/O port base */
     62  1.6.2.1  mycroft 	u_char	sc_flags;	/* Driver flags */
     63  1.6.2.1  mycroft #define	MMS_NOBLOCK	0x01
     64  1.6.2.1  mycroft 	u_char	sc_state;	/* Mouse driver state */
     65  1.6.2.1  mycroft #define MMS_OPEN	0x01	/* Device is open */
     66  1.6.2.1  mycroft #define MMS_ASLP	0x02	/* Waiting for mouse data */
     67  1.6.2.1  mycroft 	u_char	sc_status;	/* Mouse button status */
     68  1.6.2.1  mycroft 	int	sc_x, sc_y;	/* accumulated motion in the X,Y axis */
     69      1.1   andrew };
     70      1.1   andrew 
     71  1.6.2.1  mycroft static int mmsprobe __P((struct device *, struct cfdata *, void *));
     72  1.6.2.1  mycroft static void mmsforceintr __P((void *));
     73  1.6.2.1  mycroft static void mmsattach __P((struct device *, struct device *, void *));
     74  1.6.2.1  mycroft static int mmsintr __P((void *));
     75      1.1   andrew 
     76  1.6.2.1  mycroft struct cfdriver mmscd =
     77  1.6.2.1  mycroft { NULL, "mms", mmsprobe, mmsattach, sizeof (struct mms_softc) };
     78      1.1   andrew 
     79  1.6.2.1  mycroft #define MMSUNIT(dev)	(minor(dev) >> 1)
     80  1.6.2.1  mycroft #define	MMSFLAGS(dev)	(minor(dev) & 0x01)
     81      1.1   andrew 
     82  1.6.2.1  mycroft static int
     83  1.6.2.1  mycroft mmsprobe(parent, cf, aux)
     84  1.6.2.1  mycroft 	struct device *parent;
     85  1.6.2.1  mycroft 	struct cfdata *cf;
     86  1.6.2.1  mycroft 	void *aux;
     87      1.1   andrew {
     88  1.6.2.1  mycroft 	struct	isa_attach_args *ia = aux;
     89  1.6.2.1  mycroft 	u_short	iobase = ia->ia_iobase;
     90      1.1   andrew 
     91      1.1   andrew 	/* Read identification register to see if present */
     92  1.6.2.1  mycroft 	if (inb(iobase + MMS_IDENT) != 0xde)
     93  1.6.2.1  mycroft 		return 0;
     94      1.1   andrew 
     95      1.1   andrew 	/* Seems it was there; reset */
     96  1.6.2.1  mycroft 	outb(iobase + MMS_ADDR, 0x87);
     97      1.1   andrew 
     98  1.6.2.1  mycroft 	/* XXXX isa_discoverintr */
     99      1.1   andrew 
    100  1.6.2.1  mycroft 	/* reset again to disable interrupts */
    101  1.6.2.1  mycroft 	outb(iobase + MMS_ADDR, 0x87);
    102      1.1   andrew 
    103  1.6.2.1  mycroft 	ia->ia_iosize = MMS_NPORTS;
    104  1.6.2.1  mycroft 	ia->ia_drq = DRQUNK;
    105  1.6.2.1  mycroft 	ia->ia_msize = 0;
    106  1.6.2.1  mycroft 	return 1;
    107      1.1   andrew }
    108      1.1   andrew 
    109  1.6.2.1  mycroft static void
    110  1.6.2.1  mycroft mmsforceintr(aux)
    111  1.6.2.1  mycroft 	void *aux;
    112      1.1   andrew {
    113  1.6.2.1  mycroft 	struct	isa_attach_args *ia = aux;
    114  1.6.2.1  mycroft 	u_short	iobase = ia->ia_iobase;
    115      1.1   andrew 
    116  1.6.2.1  mycroft 	/* enable interrupts; expect to get one in 1/60 second */
    117  1.6.2.1  mycroft 	outb(iobase + MMS_ADDR, 0x07);
    118  1.6.2.1  mycroft 	outb(iobase + MMS_DATA, 0x09);
    119      1.1   andrew }
    120      1.1   andrew 
    121  1.6.2.1  mycroft static void
    122  1.6.2.1  mycroft mmsattach(parent, self, aux)
    123  1.6.2.1  mycroft 	struct device *parent, *self;
    124  1.6.2.1  mycroft 	void *aux;
    125      1.1   andrew {
    126  1.6.2.1  mycroft 	struct	mms_softc *sc = (struct mms_softc *)self;
    127  1.6.2.1  mycroft 	struct	isa_attach_args *ia = aux;
    128  1.6.2.1  mycroft 	u_short	iobase = ia->ia_iobase;
    129  1.6.2.1  mycroft 
    130  1.6.2.1  mycroft 	/* other initialization done by mmsprobe */
    131  1.6.2.1  mycroft 	sc->sc_iobase = iobase;
    132  1.6.2.1  mycroft 	sc->sc_state = 0;
    133      1.1   andrew 
    134  1.6.2.2  mycroft 	printf(": Microsoft mouse\n");
    135  1.6.2.2  mycroft 
    136  1.6.2.1  mycroft 	/* XXXX isa_establishintr */
    137  1.6.2.1  mycroft }
    138      1.1   andrew 
    139  1.6.2.1  mycroft int
    140  1.6.2.1  mycroft mmsopen(dev, flag)
    141  1.6.2.1  mycroft 	dev_t dev;
    142  1.6.2.1  mycroft 	int flag;
    143  1.6.2.1  mycroft {
    144  1.6.2.1  mycroft 	int	unit = MMSUNIT(dev);
    145  1.6.2.1  mycroft 	struct	mms_softc *sc;
    146  1.6.2.1  mycroft 	u_short	iobase;
    147  1.6.2.1  mycroft 
    148  1.6.2.1  mycroft 	if (unit >= mmscd.cd_ndevs)
    149  1.6.2.1  mycroft 		return ENXIO;
    150  1.6.2.2  mycroft 	sc = mmscd.cd_devs[unit];
    151  1.6.2.1  mycroft 	if (!sc)
    152  1.6.2.1  mycroft 		return ENXIO;
    153  1.6.2.1  mycroft 
    154  1.6.2.1  mycroft 	if (sc->sc_state & MMS_OPEN)
    155  1.6.2.1  mycroft 		return EBUSY;
    156  1.6.2.1  mycroft 
    157  1.6.2.1  mycroft 	sc->sc_state |= MMS_OPEN;
    158  1.6.2.1  mycroft 	sc->sc_status = 0;
    159  1.6.2.1  mycroft 	sc->sc_x = sc->sc_y = 0;
    160  1.6.2.1  mycroft 	sc->sc_q.rb_count = sc->sc_q.rb_first = sc->sc_q.rb_last = 0;
    161  1.6.2.1  mycroft 
    162  1.6.2.1  mycroft 	/* enable interrupts */
    163  1.6.2.1  mycroft 	iobase = sc->sc_iobase;
    164  1.6.2.1  mycroft 	outb(iobase + MMS_ADDR, 0x07);
    165  1.6.2.1  mycroft 	outb(iobase + MMS_DATA, 0x09);
    166      1.1   andrew 
    167  1.6.2.1  mycroft 	return 0;
    168  1.6.2.1  mycroft }
    169      1.1   andrew 
    170  1.6.2.1  mycroft int
    171  1.6.2.1  mycroft mmsclose(dev, flag)
    172  1.6.2.1  mycroft 	dev_t dev;
    173  1.6.2.1  mycroft 	int flag;
    174  1.6.2.1  mycroft {
    175  1.6.2.1  mycroft 	int	unit = MMSUNIT(dev);
    176  1.6.2.2  mycroft 	struct	mms_softc *sc = mmscd.cd_devs[unit];
    177      1.1   andrew 
    178  1.6.2.1  mycroft 	/* disable interrupts */
    179  1.6.2.1  mycroft 	outb(sc->sc_iobase + MMS_ADDR, 0x87);
    180      1.1   andrew 
    181  1.6.2.1  mycroft 	sc->sc_state &= ~MMS_OPEN;
    182      1.1   andrew 
    183  1.6.2.1  mycroft 	return 0;
    184      1.1   andrew }
    185      1.1   andrew 
    186  1.6.2.1  mycroft int
    187  1.6.2.1  mycroft mmsread(dev, uio, flag)
    188  1.6.2.1  mycroft 	dev_t dev;
    189  1.6.2.1  mycroft 	struct uio *uio;
    190  1.6.2.1  mycroft 	int flag;
    191      1.1   andrew {
    192  1.6.2.1  mycroft 	int	unit = MMSUNIT(dev);
    193  1.6.2.2  mycroft 	struct	mms_softc *sc = mmscd.cd_devs[unit];
    194  1.6.2.1  mycroft 	int	s;
    195  1.6.2.1  mycroft 	int	error;
    196  1.6.2.1  mycroft 	size_t	length;
    197  1.6.2.1  mycroft 	u_char	buffer[MMS_CHUNK];
    198      1.1   andrew 
    199      1.1   andrew 	/* Block until mouse activity occured */
    200      1.1   andrew 
    201      1.1   andrew 	s = spltty();
    202  1.6.2.1  mycroft 	while (sc->sc_q.rb_count == 0) {
    203  1.6.2.1  mycroft 		if (sc->sc_flags & MMS_NOBLOCK) {
    204      1.1   andrew 			splx(s);
    205  1.6.2.1  mycroft 			return EWOULDBLOCK;
    206      1.1   andrew 		}
    207  1.6.2.1  mycroft 		sc->sc_state |= MMS_ASLP;
    208  1.6.2.1  mycroft 		if (error = tsleep((caddr_t)sc, PZERO | PCATCH, "mmsrea", 0)) {
    209  1.6.2.1  mycroft 			sc->sc_state &= ~MMS_ASLP;
    210      1.1   andrew 			splx(s);
    211  1.6.2.1  mycroft 			return error;
    212      1.1   andrew 		}
    213      1.1   andrew 	}
    214      1.1   andrew 
    215      1.1   andrew 	/* Transfer as many chunks as possible */
    216      1.1   andrew 
    217  1.6.2.1  mycroft 	while (sc->sc_q.rb_count > 0 && uio->uio_resid > 0) {
    218  1.6.2.1  mycroft 		length = min(sc->sc_q.rb_count, uio->uio_resid);
    219      1.1   andrew 		if (length > sizeof(buffer))
    220      1.1   andrew 			length = sizeof(buffer);
    221      1.1   andrew 
    222      1.1   andrew 		/* Remove a small chunk from input queue */
    223      1.1   andrew 
    224  1.6.2.1  mycroft 		if (sc->sc_q.rb_first + length >= MMS_BSIZE) {
    225  1.6.2.1  mycroft 			size_t	left = MMS_BSIZE - sc->sc_q.rb_first;
    226  1.6.2.1  mycroft 			bcopy(&sc->sc_q.rb_data[sc->sc_q.rb_first], buffer,
    227  1.6.2.1  mycroft 			      left);
    228  1.6.2.1  mycroft 			bcopy(sc->sc_q.rb_data, &buffer[left], length - left);
    229  1.6.2.1  mycroft 		} else
    230  1.6.2.1  mycroft 			bcopy(&sc->sc_q.rb_data[sc->sc_q.rb_first], buffer,
    231  1.6.2.1  mycroft 			      length);
    232      1.1   andrew 
    233  1.6.2.1  mycroft 		sc->sc_q.rb_first = (sc->sc_q.rb_first + length) % MMS_BSIZE;
    234  1.6.2.1  mycroft 		sc->sc_q.rb_count -= length;
    235      1.1   andrew 
    236      1.1   andrew 		/* Copy data to user process */
    237      1.1   andrew 
    238  1.6.2.1  mycroft 		if (error = uiomove(buffer, length, uio))
    239      1.1   andrew 			break;
    240      1.1   andrew 	}
    241      1.1   andrew 
    242  1.6.2.1  mycroft 	/* reset counters */
    243  1.6.2.1  mycroft 	sc->sc_x = sc->sc_y = 0;
    244      1.1   andrew 
    245      1.1   andrew 	splx(s);
    246  1.6.2.1  mycroft 	return error;
    247      1.1   andrew }
    248      1.1   andrew 
    249  1.6.2.1  mycroft int
    250  1.6.2.1  mycroft mmsioctl(dev, cmd, addr, flag)
    251  1.6.2.1  mycroft 	dev_t dev;
    252  1.6.2.1  mycroft 	int cmd;
    253  1.6.2.1  mycroft 	caddr_t addr;
    254  1.6.2.1  mycroft 	int flag;
    255      1.1   andrew {
    256  1.6.2.1  mycroft 	int	unit = MMSUNIT(dev);
    257  1.6.2.2  mycroft 	struct	mms_softc *sc = mmscd.cd_devs[unit];
    258  1.6.2.1  mycroft 	struct	mouseinfo info;
    259  1.6.2.1  mycroft 	int	s;
    260  1.6.2.1  mycroft 	int	error;
    261      1.1   andrew 
    262      1.1   andrew 	switch (cmd) {
    263  1.6.2.1  mycroft 	    case MOUSEIOCREAD:
    264      1.1   andrew 		s = spltty();
    265      1.1   andrew 
    266  1.6.2.1  mycroft 		info.status = sc->sc_status;
    267  1.6.2.1  mycroft 		if (sc->sc_x || sc->sc_y)
    268      1.1   andrew 			info.status |= MOVEMENT;
    269      1.1   andrew 
    270  1.6.2.1  mycroft 		if (sc->sc_x > 127)
    271      1.1   andrew 			info.xmotion = 127;
    272  1.6.2.1  mycroft 		else if (sc->sc_x < -127)
    273  1.6.2.1  mycroft 			/* bounding at -127 avoids a bug in XFree86 */
    274  1.6.2.1  mycroft 			info.xmotion = -127;
    275      1.1   andrew 		else
    276  1.6.2.1  mycroft 			info.xmotion = sc->sc_x;
    277      1.1   andrew 
    278  1.6.2.1  mycroft 		if (sc->sc_y > 127)
    279      1.1   andrew 			info.ymotion = 127;
    280  1.6.2.1  mycroft 		else if (sc->sc_y < -127)
    281  1.6.2.1  mycroft 			info.ymotion = -127;
    282      1.1   andrew 		else
    283  1.6.2.1  mycroft 			info.ymotion = sc->sc_y;
    284      1.1   andrew 
    285  1.6.2.1  mycroft 		sc->sc_x = 0;
    286  1.6.2.1  mycroft 		sc->sc_y = 0;
    287  1.6.2.1  mycroft 		sc->sc_status &= ~BUTCHNGMASK;
    288      1.1   andrew 
    289      1.1   andrew 		splx(s);
    290      1.1   andrew 		error = copyout(&info, addr, sizeof(struct mouseinfo));
    291      1.1   andrew 		break;
    292      1.1   andrew 
    293  1.6.2.1  mycroft 	    default:
    294      1.1   andrew 		error = EINVAL;
    295      1.1   andrew 		break;
    296  1.6.2.1  mycroft 	}
    297      1.1   andrew 
    298  1.6.2.1  mycroft 	return error;
    299      1.1   andrew }
    300      1.1   andrew 
    301  1.6.2.1  mycroft int
    302  1.6.2.1  mycroft mmsintr(arg)
    303  1.6.2.1  mycroft 	void *arg;
    304      1.1   andrew {
    305  1.6.2.1  mycroft 	struct	mms_softc *sc = (struct mms_softc *)arg;
    306  1.6.2.1  mycroft 	u_short	iobase = sc->sc_iobase;
    307  1.6.2.1  mycroft 	u_char	buttons, changed, status;
    308  1.6.2.1  mycroft 	char	dx, dy;
    309  1.6.2.1  mycroft 
    310  1.6.2.1  mycroft 	if ((sc->sc_state & MMS_OPEN) == 0)
    311  1.6.2.1  mycroft 		/* interrupts not expected */
    312  1.6.2.1  mycroft 		return 0;
    313      1.1   andrew 
    314      1.1   andrew 	/* Freeze InPort registers (disabling interrupts) */
    315  1.6.2.1  mycroft 	outb(iobase + MMS_ADDR, 0x07);
    316  1.6.2.1  mycroft 	outb(iobase + MMS_DATA, 0x29);
    317      1.1   andrew 
    318  1.6.2.1  mycroft 	outb(iobase + MMS_ADDR, 0);
    319  1.6.2.1  mycroft 	status = inb(iobase + MMS_DATA);
    320      1.1   andrew 
    321      1.1   andrew 	if (status & 0x40) {
    322  1.6.2.1  mycroft 		outb(iobase + MMS_ADDR, 1);
    323  1.6.2.1  mycroft 		dx = inb(iobase + MMS_DATA);
    324  1.6.2.1  mycroft 		dx = (dx == -128) ? -127 : dx;
    325  1.6.2.1  mycroft 		outb(iobase + MMS_ADDR, 2);
    326  1.6.2.1  mycroft 		dy = inb(iobase + MMS_DATA);
    327      1.1   andrew 		dy = (dy == -128) ? 127 : -dy;
    328  1.6.2.1  mycroft 	} else
    329      1.1   andrew 		dx = dy = 0;
    330      1.1   andrew 
    331      1.1   andrew 	/* Unfreeze InPort Registers (re-enables interrupts) */
    332  1.6.2.1  mycroft 	outb(iobase + MMS_ADDR, 0x07);
    333  1.6.2.1  mycroft 	outb(iobase + MMS_DATA, 0x09);
    334      1.1   andrew 
    335  1.6.2.1  mycroft 	buttons = status & BUTSTATMASK;
    336  1.6.2.1  mycroft 	changed = status & BUTCHNGMASK;
    337  1.6.2.1  mycroft 	sc->sc_status = buttons | (sc->sc_status & ~BUTSTATMASK) | changed;
    338  1.6.2.1  mycroft 
    339  1.6.2.1  mycroft 	if (dx || dy || changed) {
    340  1.6.2.1  mycroft 		int	last = sc->sc_q.rb_last;
    341  1.6.2.1  mycroft 		char	*cp = &sc->sc_q.rb_data[last];
    342  1.6.2.1  mycroft 		int	count = sc->sc_q.rb_count;
    343  1.6.2.1  mycroft 
    344  1.6.2.1  mycroft 		/* Update accumulated movements */
    345  1.6.2.1  mycroft 		sc->sc_x += dx;
    346  1.6.2.1  mycroft 		sc->sc_y += dy;
    347  1.6.2.1  mycroft 
    348  1.6.2.1  mycroft 		if ((count += 5) > MMS_BSIZE)
    349  1.6.2.1  mycroft 			return 1;
    350  1.6.2.1  mycroft 		sc->sc_q.rb_count = count;
    351  1.6.2.1  mycroft 
    352  1.6.2.1  mycroft #define	next() \
    353  1.6.2.1  mycroft 		if (++last >= MMS_BSIZE) {	\
    354  1.6.2.1  mycroft 			last = 0;		\
    355  1.6.2.1  mycroft 			cp = sc->sc_q.rb_data;	\
    356  1.6.2.1  mycroft 		} else				\
    357  1.6.2.1  mycroft 			cp++;
    358  1.6.2.1  mycroft 		*cp = 0x80 | (~status & BUTSTATMASK);
    359  1.6.2.1  mycroft 		next();
    360  1.6.2.1  mycroft 		*cp = dx;
    361  1.6.2.1  mycroft 		next();
    362  1.6.2.1  mycroft 		*cp = dy;
    363  1.6.2.1  mycroft 		next();
    364  1.6.2.1  mycroft 		*cp = 0;
    365  1.6.2.1  mycroft 		next();
    366  1.6.2.1  mycroft 		*cp = 0;
    367  1.6.2.1  mycroft 		next();
    368  1.6.2.1  mycroft 		sc->sc_q.rb_last = last;
    369      1.1   andrew 
    370  1.6.2.1  mycroft 		if (sc->sc_state & MMS_ASLP) {
    371  1.6.2.1  mycroft 			sc->sc_state &= ~MMS_ASLP;
    372      1.5   andrew 			wakeup((caddr_t)sc);
    373      1.1   andrew 		}
    374  1.6.2.1  mycroft 		selwakeup(&sc->sc_rsel);
    375  1.6.2.1  mycroft 	}
    376  1.6.2.1  mycroft 
    377  1.6.2.1  mycroft 	return 1;
    378      1.1   andrew }
    379      1.1   andrew 
    380  1.6.2.1  mycroft int
    381  1.6.2.1  mycroft mmsselect(dev, rw, p)
    382  1.6.2.1  mycroft 	dev_t dev;
    383  1.6.2.1  mycroft 	int rw;
    384  1.6.2.1  mycroft 	struct proc *p;
    385      1.1   andrew {
    386  1.6.2.1  mycroft 	int	unit = MMSUNIT(dev);
    387  1.6.2.2  mycroft 	struct	mms_softc *sc = mmscd.cd_devs[unit];
    388  1.6.2.1  mycroft 	int	s;
    389  1.6.2.1  mycroft 	int	ret;
    390      1.1   andrew 
    391      1.1   andrew 	if (rw == FWRITE)
    392  1.6.2.1  mycroft 		return 0;
    393      1.1   andrew 
    394      1.1   andrew 	s = spltty();
    395  1.6.2.1  mycroft 	if (sc->sc_q.rb_count)
    396      1.1   andrew 		ret = 1;
    397      1.1   andrew 	else {
    398  1.6.2.1  mycroft 		selrecord(p, &sc->sc_rsel);
    399      1.1   andrew 		ret = 0;
    400      1.1   andrew 	}
    401      1.1   andrew 	splx(s);
    402      1.1   andrew 
    403  1.6.2.1  mycroft 	return ret;
    404      1.1   andrew }
    405