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lms.c revision 1.6.2.4
      1      1.1   andrew /*-
      2  1.6.2.4  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  1.6.2.4  mycroft  *	$Id: lms.c,v 1.6.2.4 1993/09/29 15:24:14 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 LMS_DATA	0       /* Offset for data port, read-only */
     44  1.6.2.1  mycroft #define LMS_SIGN	1       /* Offset for signature port, read-write */
     45  1.6.2.1  mycroft #define LMS_INTR	2       /* Offset for interrupt port, read-only */
     46  1.6.2.1  mycroft #define LMS_CNTRL	2       /* Offset for control port, write-only */
     47  1.6.2.1  mycroft #define LMS_CONFIG	3	/* for configuration port, read-write */
     48  1.6.2.1  mycroft #define	LMS_NPORTS	4
     49  1.6.2.1  mycroft 
     50  1.6.2.1  mycroft #define	LMS_CHUNK	128	/* chunk size for read */
     51  1.6.2.1  mycroft #define	LMS_BSIZE	1024	/* buffer size */
     52  1.6.2.1  mycroft 
     53  1.6.2.1  mycroft struct lms_softc {		/* Driver status information */
     54  1.6.2.1  mycroft 	struct ringbuf {	/* Input queue */
     55  1.6.2.1  mycroft 		int rb_count, rb_first, rb_last;
     56  1.6.2.1  mycroft 		char rb_data[LMS_BSIZE];
     57  1.6.2.1  mycroft 	} sc_q;
     58  1.6.2.1  mycroft 	struct	selinfo sc_rsel;
     59  1.6.2.1  mycroft 	u_short	sc_iobase;	/* I/O port base */
     60  1.6.2.1  mycroft 	u_char	sc_flags;	/* Driver flags */
     61  1.6.2.3  mycroft #define	LMS_NOBLOCK	0x01
     62  1.6.2.1  mycroft 	u_char	sc_state;	/* Mouse driver state */
     63  1.6.2.2  mycroft #define LMS_OPEN	0x01	/* Device is open */
     64  1.6.2.2  mycroft #define LMS_ASLP	0x02	/* Waiting for mouse data */
     65  1.6.2.1  mycroft 	u_char	sc_status;	/* Mouse button status */
     66  1.6.2.1  mycroft 	int	sc_x, sc_y;	/* accumulated motion in the X,Y axis */
     67      1.1   andrew };
     68      1.1   andrew 
     69  1.6.2.1  mycroft static int lmsprobe __P((struct device *, struct cfdata *, void *));
     70  1.6.2.1  mycroft static void lmsforceintr __P((void *));
     71  1.6.2.1  mycroft static void lmsattach __P((struct device *, struct device *, void *));
     72  1.6.2.1  mycroft static int lmsintr __P((void *));
     73      1.1   andrew 
     74  1.6.2.1  mycroft struct cfdriver lmscd =
     75  1.6.2.1  mycroft { NULL, "lms", lmsprobe, lmsattach, sizeof (struct lms_softc) };
     76      1.1   andrew 
     77  1.6.2.1  mycroft #define LMSUNIT(dev)	(minor(dev) >> 1)
     78  1.6.2.1  mycroft #define	LMSFLAGS(dev)	(minor(dev) & 0x01)
     79      1.1   andrew 
     80  1.6.2.1  mycroft static int
     81  1.6.2.1  mycroft lmsprobe(parent, cf, aux)
     82  1.6.2.1  mycroft 	struct device *parent;
     83  1.6.2.1  mycroft 	struct cfdata *cf;
     84  1.6.2.1  mycroft 	void *aux;
     85      1.1   andrew {
     86  1.6.2.1  mycroft 	struct	isa_attach_args *ia = aux;
     87  1.6.2.1  mycroft 	u_short	iobase = ia->ia_iobase;
     88      1.1   andrew 
     89      1.1   andrew 	/* Configure and check for port present */
     90  1.6.2.1  mycroft 	outb(iobase + LMS_CONFIG, 0x91);
     91  1.6.2.1  mycroft 	delay(10);
     92  1.6.2.1  mycroft 	outb(iobase + LMS_SIGN, 0x0c);
     93  1.6.2.1  mycroft 	delay(10);
     94  1.6.2.1  mycroft 	if (inb(iobase + LMS_SIGN) != 0x0c)
     95  1.6.2.1  mycroft 		return 0;
     96  1.6.2.1  mycroft 	outb(iobase + LMS_SIGN, 0x50);
     97  1.6.2.1  mycroft 	delay(10);
     98  1.6.2.1  mycroft 	if (inb(iobase + LMS_SIGN) != 0x50)
     99  1.6.2.1  mycroft 		return 0;
    100  1.6.2.1  mycroft 
    101  1.6.2.1  mycroft 	/* XXXX isa_discoverintr */
    102  1.6.2.1  mycroft 
    103  1.6.2.1  mycroft 	/* disable interrupts */
    104  1.6.2.1  mycroft 	outb(iobase + LMS_CNTRL, 0x10);
    105  1.6.2.1  mycroft 
    106  1.6.2.1  mycroft 	ia->ia_iosize = LMS_NPORTS;
    107  1.6.2.1  mycroft 	ia->ia_drq = DRQUNK;
    108  1.6.2.1  mycroft 	ia->ia_msize = 0;
    109  1.6.2.1  mycroft 	return 1;
    110      1.1   andrew }
    111      1.1   andrew 
    112  1.6.2.1  mycroft static void
    113  1.6.2.1  mycroft lmsforceintr(aux)
    114  1.6.2.1  mycroft 	void *aux;
    115      1.1   andrew {
    116  1.6.2.1  mycroft 	struct	isa_attach_args *ia = aux;
    117      1.1   andrew 
    118  1.6.2.1  mycroft 	/* enable interrupts; expect to get one in 1/60 second */
    119  1.6.2.1  mycroft 	outb(ia->ia_iobase + LMS_CNTRL, 0);
    120      1.1   andrew }
    121      1.1   andrew 
    122  1.6.2.1  mycroft static void
    123  1.6.2.1  mycroft lmsattach(parent, self, aux)
    124  1.6.2.1  mycroft 	struct device *parent, *self;
    125  1.6.2.1  mycroft 	void *aux;
    126      1.1   andrew {
    127  1.6.2.1  mycroft 	struct	lms_softc *sc = (struct lms_softc *)self;
    128  1.6.2.1  mycroft 	struct	isa_attach_args *ia = aux;
    129  1.6.2.1  mycroft 	u_short	iobase = ia->ia_iobase;
    130  1.6.2.1  mycroft 
    131  1.6.2.1  mycroft 	/* other initialization done by lmsprobe */
    132  1.6.2.1  mycroft 	sc->sc_iobase = iobase;
    133  1.6.2.1  mycroft 	sc->sc_state = 0;
    134      1.1   andrew 
    135  1.6.2.1  mycroft 	/* XXXX isa_establishintr */
    136      1.1   andrew }
    137      1.1   andrew 
    138  1.6.2.1  mycroft int
    139  1.6.2.1  mycroft lmsopen(dev, flag)
    140  1.6.2.1  mycroft 	dev_t dev;
    141  1.6.2.1  mycroft 	int flag;
    142      1.1   andrew {
    143  1.6.2.1  mycroft 	int	unit = LMSUNIT(dev);
    144  1.6.2.1  mycroft 	struct	lms_softc *sc;
    145      1.1   andrew 
    146  1.6.2.1  mycroft 	if (unit >= lmscd.cd_ndevs)
    147  1.6.2.1  mycroft 		return ENXIO;
    148  1.6.2.1  mycroft 	sc = (struct lms_softc *)lmscd.cd_devs[unit];
    149  1.6.2.1  mycroft 	if (!sc)
    150  1.6.2.1  mycroft 		return ENXIO;
    151  1.6.2.1  mycroft 
    152  1.6.2.2  mycroft 	if (sc->sc_state & LMS_OPEN)
    153  1.6.2.1  mycroft 		return EBUSY;
    154  1.6.2.1  mycroft 
    155  1.6.2.2  mycroft 	sc->sc_state |= LMS_OPEN;
    156  1.6.2.1  mycroft 	sc->sc_status = 0;
    157  1.6.2.1  mycroft 	sc->sc_x = sc->sc_y = 0;
    158  1.6.2.1  mycroft 	sc->sc_q.rb_count = sc->sc_q.rb_first = sc->sc_q.rb_last = 0;
    159      1.1   andrew 
    160  1.6.2.1  mycroft 	/* enable interrupts */
    161  1.6.2.1  mycroft 	outb(sc->sc_iobase + LMS_CNTRL, 0);
    162      1.1   andrew 
    163  1.6.2.1  mycroft 	return 0;
    164  1.6.2.1  mycroft }
    165      1.1   andrew 
    166  1.6.2.1  mycroft int
    167  1.6.2.1  mycroft lmsclose(dev, flag)
    168  1.6.2.1  mycroft 	dev_t dev;
    169  1.6.2.1  mycroft 	int flag;
    170  1.6.2.1  mycroft {
    171  1.6.2.1  mycroft 	int	unit = LMSUNIT(dev);
    172  1.6.2.1  mycroft 	struct	lms_softc *sc = (struct lms_softc *)lmscd.cd_devs[unit];
    173      1.1   andrew 
    174  1.6.2.1  mycroft 	/* disable interrupts */
    175  1.6.2.1  mycroft 	outb(sc->sc_iobase + LMS_CNTRL, 0x10);
    176      1.1   andrew 
    177  1.6.2.2  mycroft 	sc->sc_state &= ~LMS_OPEN;
    178      1.1   andrew 
    179  1.6.2.1  mycroft 	return 0;
    180      1.1   andrew }
    181      1.1   andrew 
    182  1.6.2.1  mycroft int
    183  1.6.2.1  mycroft lmsread(dev, uio, flag)
    184  1.6.2.1  mycroft 	dev_t dev;
    185  1.6.2.1  mycroft 	struct uio *uio;
    186  1.6.2.1  mycroft 	int flag;
    187      1.1   andrew {
    188  1.6.2.1  mycroft 	int	unit = LMSUNIT(dev);
    189  1.6.2.1  mycroft 	struct	lms_softc *sc = (struct lms_softc *)lmscd.cd_devs[unit];
    190  1.6.2.1  mycroft 	int	s;
    191  1.6.2.1  mycroft 	int	error;
    192  1.6.2.1  mycroft 	size_t	length;
    193  1.6.2.1  mycroft 	u_char	buffer[LMS_CHUNK];
    194      1.1   andrew 
    195      1.1   andrew 	/* Block until mouse activity occured */
    196      1.1   andrew 
    197      1.1   andrew 	s = spltty();
    198  1.6.2.1  mycroft 	while (sc->sc_q.rb_count == 0) {
    199  1.6.2.3  mycroft 		if (sc->sc_flags & LMS_NOBLOCK) {
    200      1.1   andrew 			splx(s);
    201  1.6.2.1  mycroft 			return EWOULDBLOCK;
    202      1.1   andrew 		}
    203  1.6.2.2  mycroft 		sc->sc_state |= LMS_ASLP;
    204  1.6.2.1  mycroft 		if (error = tsleep((caddr_t)sc, PZERO | PCATCH, "lmsrea", 0)) {
    205  1.6.2.2  mycroft 			sc->sc_state &= ~LMS_ASLP;
    206      1.1   andrew 			splx(s);
    207  1.6.2.1  mycroft 			return error;
    208      1.1   andrew 		}
    209      1.1   andrew 	}
    210      1.1   andrew 
    211      1.1   andrew 	/* Transfer as many chunks as possible */
    212      1.1   andrew 
    213  1.6.2.1  mycroft 	while (sc->sc_q.rb_count > 0 && uio->uio_resid > 0) {
    214  1.6.2.1  mycroft 		length = min(sc->sc_q.rb_count, uio->uio_resid);
    215      1.1   andrew 		if (length > sizeof(buffer))
    216      1.1   andrew 			length = sizeof(buffer);
    217      1.1   andrew 
    218      1.1   andrew 		/* Remove a small chunk from input queue */
    219      1.1   andrew 
    220  1.6.2.1  mycroft 		if (sc->sc_q.rb_first + length >= LMS_BSIZE) {
    221  1.6.2.1  mycroft 			size_t	left = LMS_BSIZE - sc->sc_q.rb_first;
    222  1.6.2.1  mycroft 			bcopy(&sc->sc_q.rb_data[sc->sc_q.rb_first], buffer,
    223  1.6.2.1  mycroft 			      left);
    224  1.6.2.1  mycroft 			bcopy(sc->sc_q.rb_data, &buffer[left], length - left);
    225  1.6.2.1  mycroft 		} else
    226  1.6.2.1  mycroft 			bcopy(&sc->sc_q.rb_data[sc->sc_q.rb_first], buffer,
    227  1.6.2.1  mycroft 			      length);
    228      1.1   andrew 
    229  1.6.2.1  mycroft 		sc->sc_q.rb_first = (sc->sc_q.rb_first + length) % LMS_BSIZE;
    230  1.6.2.1  mycroft 		sc->sc_q.rb_count -= length;
    231      1.1   andrew 
    232      1.1   andrew 		/* Copy data to user process */
    233      1.1   andrew 
    234  1.6.2.1  mycroft 		if (error = uiomove(buffer, length, uio))
    235      1.1   andrew 			break;
    236      1.1   andrew 	}
    237      1.1   andrew 
    238  1.6.2.1  mycroft 	/* reset counters */
    239  1.6.2.1  mycroft 	sc->sc_x = sc->sc_y = 0;
    240      1.1   andrew 
    241      1.1   andrew 	splx(s);
    242  1.6.2.1  mycroft 	return error;
    243      1.1   andrew }
    244      1.1   andrew 
    245  1.6.2.1  mycroft int
    246  1.6.2.1  mycroft lmsioctl(dev, cmd, addr, flag)
    247  1.6.2.1  mycroft 	dev_t dev;
    248  1.6.2.1  mycroft 	int cmd;
    249  1.6.2.1  mycroft 	caddr_t addr;
    250  1.6.2.1  mycroft 	int flag;
    251      1.1   andrew {
    252  1.6.2.1  mycroft 	int	unit = LMSUNIT(dev);
    253  1.6.2.1  mycroft 	struct	lms_softc *sc = (struct lms_softc *)lmscd.cd_devs[unit];
    254  1.6.2.1  mycroft 	struct	mouseinfo info;
    255  1.6.2.1  mycroft 	int	s;
    256  1.6.2.1  mycroft 	int	error;
    257      1.1   andrew 
    258      1.1   andrew 	switch (cmd) {
    259  1.6.2.1  mycroft 	    case MOUSEIOCREAD:
    260      1.1   andrew 		s = spltty();
    261      1.1   andrew 
    262  1.6.2.1  mycroft 		info.status = sc->sc_status;
    263  1.6.2.1  mycroft 		if (sc->sc_x || sc->sc_y)
    264      1.1   andrew 			info.status |= MOVEMENT;
    265      1.1   andrew 
    266  1.6.2.1  mycroft 		if (sc->sc_x > 127)
    267      1.1   andrew 			info.xmotion = 127;
    268  1.6.2.1  mycroft 		else if (sc->sc_x < -127)
    269  1.6.2.1  mycroft 			/* bounding at -127 avoids a bug in XFree86 */
    270      1.3  mycroft 			info.xmotion = -127;
    271      1.1   andrew 		else
    272  1.6.2.1  mycroft 			info.xmotion = sc->sc_x;
    273      1.1   andrew 
    274  1.6.2.1  mycroft 		if (sc->sc_y > 127)
    275      1.1   andrew 			info.ymotion = 127;
    276  1.6.2.1  mycroft 		else if (sc->sc_y < -127)
    277      1.3  mycroft 			info.ymotion = -127;
    278      1.1   andrew 		else
    279  1.6.2.1  mycroft 			info.ymotion = sc->sc_y;
    280      1.1   andrew 
    281  1.6.2.1  mycroft 		sc->sc_x = 0;
    282  1.6.2.1  mycroft 		sc->sc_y = 0;
    283  1.6.2.1  mycroft 		sc->sc_status &= ~BUTCHNGMASK;
    284      1.1   andrew 
    285      1.1   andrew 		splx(s);
    286      1.1   andrew 		error = copyout(&info, addr, sizeof(struct mouseinfo));
    287      1.1   andrew 		break;
    288      1.1   andrew 
    289  1.6.2.1  mycroft 	    default:
    290      1.1   andrew 		error = EINVAL;
    291      1.1   andrew 		break;
    292  1.6.2.1  mycroft 	}
    293      1.1   andrew 
    294  1.6.2.1  mycroft 	return error;
    295      1.1   andrew }
    296      1.1   andrew 
    297  1.6.2.1  mycroft int
    298  1.6.2.1  mycroft lmsintr(arg)
    299  1.6.2.1  mycroft 	void *arg;
    300      1.1   andrew {
    301  1.6.2.1  mycroft 	struct	lms_softc *sc = (struct lms_softc *)arg;
    302  1.6.2.1  mycroft 	u_short	iobase = sc->sc_iobase;
    303  1.6.2.1  mycroft 	u_char	hi, lo, buttons, changed;
    304  1.6.2.1  mycroft 	char	dx, dy;
    305  1.6.2.1  mycroft 
    306  1.6.2.2  mycroft 	if ((sc->sc_state & LMS_OPEN) == 0)
    307  1.6.2.1  mycroft 		/* interrupts not expected */
    308  1.6.2.1  mycroft 		return 0;
    309  1.6.2.1  mycroft 
    310  1.6.2.1  mycroft 	outb(iobase + LMS_CNTRL, 0xab);
    311  1.6.2.1  mycroft 	hi = inb(iobase + LMS_DATA);
    312  1.6.2.1  mycroft 	outb(iobase + LMS_CNTRL, 0x90);
    313  1.6.2.1  mycroft 	lo = inb(iobase + LMS_DATA);
    314  1.6.2.1  mycroft 	dx = ((hi & 0x0f) << 4) | (lo & 0x0f);
    315  1.6.2.1  mycroft 	/* bounding at -127 avoids a bug in XFree86 */
    316      1.3  mycroft 	dx = (dx == -128) ? -127 : dx;
    317      1.3  mycroft 
    318  1.6.2.1  mycroft 	outb(iobase + LMS_CNTRL, 0xf0);
    319  1.6.2.1  mycroft 	hi = inb(iobase + LMS_DATA);
    320  1.6.2.1  mycroft 	outb(iobase + LMS_CNTRL, 0xd0);
    321  1.6.2.1  mycroft 	lo = inb(iobase + LMS_DATA);
    322  1.6.2.1  mycroft 	dy = ((hi & 0x0f) << 4) | (lo & 0x0f);
    323      1.1   andrew 	dy = (dy == -128) ? 127 : -dy;
    324      1.3  mycroft 
    325  1.6.2.1  mycroft 	outb(iobase + LMS_CNTRL, 0);
    326  1.6.2.1  mycroft 
    327  1.6.2.4  mycroft 	buttons = (~hi >> 5) & 0x07;
    328  1.6.2.4  mycroft 	changed = ((buttons ^ sc->sc_status) & 0x07) << 3;
    329  1.6.2.4  mycroft 	sc->sc_status = buttons | (sc->sc_status & ~BUTSTATMASK) | changed;
    330  1.6.2.1  mycroft 
    331  1.6.2.4  mycroft 	if (dx || dy || changed) {
    332  1.6.2.1  mycroft 		int	last = sc->sc_q.rb_last;
    333  1.6.2.1  mycroft 		char	*cp = &sc->sc_q.rb_data[last];
    334  1.6.2.1  mycroft 		int	count = sc->sc_q.rb_count;
    335  1.6.2.1  mycroft 
    336  1.6.2.1  mycroft 		/* Update accumulated movements */
    337  1.6.2.1  mycroft 		sc->sc_x += dx;
    338  1.6.2.1  mycroft 		sc->sc_y += dy;
    339  1.6.2.1  mycroft 
    340  1.6.2.1  mycroft 		if ((count += 5) > LMS_BSIZE)
    341  1.6.2.1  mycroft 			return 1;
    342  1.6.2.1  mycroft 		sc->sc_q.rb_count = count;
    343  1.6.2.1  mycroft 
    344  1.6.2.1  mycroft #define	next() \
    345  1.6.2.1  mycroft 		if (++last >= LMS_BSIZE) {	\
    346  1.6.2.1  mycroft 			last = 0;		\
    347  1.6.2.1  mycroft 			cp = sc->sc_q.rb_data;	\
    348  1.6.2.1  mycroft 		} else				\
    349  1.6.2.1  mycroft 			cp++;
    350  1.6.2.1  mycroft 		*cp = 0x80 | (buttons ^ BUTSTATMASK);
    351  1.6.2.1  mycroft 		next();
    352  1.6.2.1  mycroft 		*cp = dx;
    353  1.6.2.1  mycroft 		next();
    354  1.6.2.1  mycroft 		*cp = dy;
    355  1.6.2.1  mycroft 		next();
    356  1.6.2.1  mycroft 		*cp = 0;
    357  1.6.2.1  mycroft 		next();
    358  1.6.2.1  mycroft 		*cp = 0;
    359  1.6.2.1  mycroft 		next();
    360  1.6.2.1  mycroft 		sc->sc_q.rb_last = last;
    361      1.1   andrew 
    362  1.6.2.2  mycroft 		if (sc->sc_state & LMS_ASLP) {
    363  1.6.2.2  mycroft 			sc->sc_state &= ~LMS_ASLP;
    364      1.5   andrew 			wakeup((caddr_t)sc);
    365      1.1   andrew 		}
    366  1.6.2.1  mycroft 		selwakeup(&sc->sc_rsel);
    367      1.5   andrew 	}
    368  1.6.2.1  mycroft 
    369  1.6.2.1  mycroft 	return 1;
    370      1.1   andrew }
    371      1.1   andrew 
    372  1.6.2.1  mycroft int
    373  1.6.2.1  mycroft lmsselect(dev, rw, p)
    374  1.6.2.1  mycroft 	dev_t dev;
    375  1.6.2.1  mycroft 	int rw;
    376  1.6.2.1  mycroft 	struct proc *p;
    377      1.1   andrew {
    378  1.6.2.1  mycroft 	int	unit = LMSUNIT(dev);
    379  1.6.2.1  mycroft 	struct	lms_softc *sc = (struct lms_softc *)lmscd.cd_devs[unit];
    380  1.6.2.1  mycroft 	int	s;
    381  1.6.2.1  mycroft 	int	ret;
    382      1.1   andrew 
    383      1.1   andrew 	if (rw == FWRITE)
    384  1.6.2.1  mycroft 		return 0;
    385      1.1   andrew 
    386      1.1   andrew 	s = spltty();
    387  1.6.2.1  mycroft 	if (sc->sc_q.rb_count)
    388      1.1   andrew 		ret = 1;
    389      1.1   andrew 	else {
    390  1.6.2.1  mycroft 		selrecord(p, &sc->sc_rsel);
    391      1.1   andrew 		ret = 0;
    392      1.1   andrew 	}
    393      1.1   andrew 	splx(s);
    394      1.1   andrew 
    395  1.6.2.1  mycroft 	return ret;
    396      1.1   andrew }
    397