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uhid.c revision 1.76.22.2
      1 /*	$NetBSD: uhid.c,v 1.76.22.2 2008/02/18 21:06:26 mjf Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1998, 2004 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Lennart Augustsson (lennart (at) augustsson.net) at
      9  * Carlstedt Research & Technology.
     10  *
     11  * Redistribution and use in source and binary forms, with or without
     12  * modification, are permitted provided that the following conditions
     13  * are met:
     14  * 1. Redistributions of source code must retain the above copyright
     15  *    notice, this list of conditions and the following disclaimer.
     16  * 2. Redistributions in binary form must reproduce the above copyright
     17  *    notice, this list of conditions and the following disclaimer in the
     18  *    documentation and/or other materials provided with the distribution.
     19  * 3. All advertising materials mentioning features or use of this software
     20  *    must display the following acknowledgement:
     21  *        This product includes software developed by the NetBSD
     22  *        Foundation, Inc. and its contributors.
     23  * 4. Neither the name of The NetBSD Foundation nor the names of its
     24  *    contributors may be used to endorse or promote products derived
     25  *    from this software without specific prior written permission.
     26  *
     27  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     28  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     29  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     30  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     31  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     32  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     33  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     34  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     35  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     36  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     37  * POSSIBILITY OF SUCH DAMAGE.
     38  */
     39 
     40 /*
     41  * HID spec: http://www.usb.org/developers/devclass_docs/HID1_11.pdf
     42  */
     43 
     44 #include <sys/cdefs.h>
     45 __KERNEL_RCSID(0, "$NetBSD: uhid.c,v 1.76.22.2 2008/02/18 21:06:26 mjf Exp $");
     46 
     47 #include "opt_compat_netbsd.h"
     48 
     49 #include <sys/param.h>
     50 #include <sys/systm.h>
     51 #include <sys/kernel.h>
     52 #include <sys/malloc.h>
     53 #include <sys/signalvar.h>
     54 #include <sys/device.h>
     55 #include <sys/ioctl.h>
     56 #include <sys/conf.h>
     57 #include <sys/tty.h>
     58 #include <sys/file.h>
     59 #include <sys/select.h>
     60 #include <sys/proc.h>
     61 #include <sys/vnode.h>
     62 #include <sys/poll.h>
     63 
     64 #include <dev/usb/usb.h>
     65 #include <dev/usb/usbhid.h>
     66 
     67 #include <dev/usb/usbdevs.h>
     68 #include <dev/usb/usbdi.h>
     69 #include <dev/usb/usbdi_util.h>
     70 #include <dev/usb/hid.h>
     71 #include <dev/usb/usb_quirks.h>
     72 
     73 #include <dev/usb/uhidev.h>
     74 
     75 #ifdef UHID_DEBUG
     76 #define DPRINTF(x)	if (uhiddebug) logprintf x
     77 #define DPRINTFN(n,x)	if (uhiddebug>(n)) logprintf x
     78 int	uhiddebug = 0;
     79 #else
     80 #define DPRINTF(x)
     81 #define DPRINTFN(n,x)
     82 #endif
     83 
     84 struct uhid_softc {
     85 	struct uhidev sc_hdev;
     86 
     87 	int sc_isize;
     88 	int sc_osize;
     89 	int sc_fsize;
     90 
     91 	u_char *sc_obuf;
     92 
     93 	struct clist sc_q;
     94 	struct selinfo sc_rsel;
     95 	usb_proc_ptr sc_async;	/* process that wants SIGIO */
     96 	u_char sc_state;	/* driver state */
     97 #define	UHID_ASLP	0x01	/* waiting for device data */
     98 #define UHID_IMMED	0x02	/* return read data immediately */
     99 
    100 	int sc_refcnt;
    101 	u_char sc_dying;
    102 };
    103 
    104 #define	UHIDUNIT(dev)	(minor(dev))
    105 #define	UHID_CHUNK	128	/* chunk size for read */
    106 #define	UHID_BSIZE	1020	/* buffer size */
    107 
    108 dev_type_open(uhidopen);
    109 dev_type_close(uhidclose);
    110 dev_type_read(uhidread);
    111 dev_type_write(uhidwrite);
    112 dev_type_ioctl(uhidioctl);
    113 dev_type_poll(uhidpoll);
    114 dev_type_kqfilter(uhidkqfilter);
    115 
    116 const struct cdevsw uhid_cdevsw = {
    117 	uhidopen, uhidclose, uhidread, uhidwrite, uhidioctl,
    118 	nostop, notty, uhidpoll, nommap, uhidkqfilter, D_OTHER,
    119 };
    120 
    121 Static void uhid_intr(struct uhidev *, void *, u_int len);
    122 
    123 Static int uhid_do_read(struct uhid_softc *, struct uio *uio, int);
    124 Static int uhid_do_write(struct uhid_softc *, struct uio *uio, int);
    125 Static int uhid_do_ioctl(struct uhid_softc*, u_long, void *, int, struct lwp *);
    126 
    127 USB_DECLARE_DRIVER(uhid);
    128 
    129 int
    130 uhid_match(struct device *parent, struct cfdata *match,
    131     void *aux)
    132 {
    133 #ifdef UHID_DEBUG
    134 	struct uhidev_attach_arg *uha = aux;
    135 #endif
    136 
    137 	DPRINTF(("uhid_match: report=%d\n", uha->reportid));
    138 
    139 	if (match->cf_flags & 1)
    140 		return (UMATCH_HIGHEST);
    141 	else
    142 		return (UMATCH_IFACECLASS_GENERIC);
    143 }
    144 
    145 void
    146 uhid_attach(struct device *parent, struct device *self, void *aux)
    147 {
    148 	struct uhid_softc *sc = (struct uhid_softc *)self;
    149 	struct uhidev_attach_arg *uha = aux;
    150 	int size, repid;
    151 	void *desc;
    152 
    153 	sc->sc_hdev.sc_intr = uhid_intr;
    154 	sc->sc_hdev.sc_parent = uha->parent;
    155 	sc->sc_hdev.sc_report_id = uha->reportid;
    156 
    157 	uhidev_get_report_desc(uha->parent, &desc, &size);
    158 	repid = uha->reportid;
    159 	sc->sc_isize = hid_report_size(desc, size, hid_input,   repid);
    160 	sc->sc_osize = hid_report_size(desc, size, hid_output,  repid);
    161 	sc->sc_fsize = hid_report_size(desc, size, hid_feature, repid);
    162 
    163 	printf(": input=%d, output=%d, feature=%d\n",
    164 	       sc->sc_isize, sc->sc_osize, sc->sc_fsize);
    165 
    166 	if (!pmf_device_register(self, NULL, NULL))
    167 		aprint_error_dev(self, "couldn't establish power handler\n");
    168 
    169 	USB_ATTACH_SUCCESS_RETURN;
    170 }
    171 
    172 int
    173 uhid_activate(device_ptr_t self, enum devact act)
    174 {
    175 	struct uhid_softc *sc = (struct uhid_softc *)self;
    176 
    177 	switch (act) {
    178 	case DVACT_ACTIVATE:
    179 		return (EOPNOTSUPP);
    180 
    181 	case DVACT_DEACTIVATE:
    182 		sc->sc_dying = 1;
    183 		break;
    184 	}
    185 	return (0);
    186 }
    187 
    188 int
    189 uhid_detach(struct device *self, int flags)
    190 {
    191 	struct uhid_softc *sc = (struct uhid_softc *)self;
    192 	int s;
    193 	int maj, mn;
    194 
    195 	DPRINTF(("uhid_detach: sc=%p flags=%d\n", sc, flags));
    196 
    197 	sc->sc_dying = 1;
    198 
    199 	if (sc->sc_hdev.sc_state & UHIDEV_OPEN) {
    200 		s = splusb();
    201 		if (--sc->sc_refcnt >= 0) {
    202 			/* Wake everyone */
    203 			wakeup(&sc->sc_q);
    204 			/* Wait for processes to go away. */
    205 			usb_detach_wait(USBDEV(sc->sc_hdev.sc_dev));
    206 		}
    207 		splx(s);
    208 	}
    209 
    210 	/* locate the major number */
    211 #if defined(__NetBSD__)
    212 	maj = cdevsw_lookup_major(&uhid_cdevsw);
    213 #elif defined(__OpenBSD__)
    214 	for (maj = 0; maj < nchrdev; maj++)
    215 		if (cdevsw[maj].d_open == uhidopen)
    216 			break;
    217 #endif
    218 
    219 	/* Nuke the vnodes for any open instances (calls close). */
    220 	mn = device_unit(self);
    221 	vdevgone(maj, mn, mn, VCHR);
    222 
    223 #if 0
    224 	usbd_add_drv_event(USB_EVENT_DRIVER_DETACH,
    225 			   sc->sc_hdev.sc_parent->sc_udev,
    226 			   USBDEV(sc->sc_hdev.sc_dev));
    227 #endif
    228 
    229 	return (0);
    230 }
    231 
    232 void
    233 uhid_intr(struct uhidev *addr, void *data, u_int len)
    234 {
    235 	struct uhid_softc *sc = (struct uhid_softc *)addr;
    236 
    237 #ifdef UHID_DEBUG
    238 	if (uhiddebug > 5) {
    239 		u_int32_t i;
    240 
    241 		DPRINTF(("uhid_intr: data ="));
    242 		for (i = 0; i < len; i++)
    243 			DPRINTF((" %02x", ((u_char *)data)[i]));
    244 		DPRINTF(("\n"));
    245 	}
    246 #endif
    247 
    248 	(void)b_to_q(data, len, &sc->sc_q);
    249 
    250 	if (sc->sc_state & UHID_ASLP) {
    251 		sc->sc_state &= ~UHID_ASLP;
    252 		DPRINTFN(5, ("uhid_intr: waking %p\n", &sc->sc_q));
    253 		wakeup(&sc->sc_q);
    254 	}
    255 	selnotify(&sc->sc_rsel, 0);
    256 	if (sc->sc_async != NULL) {
    257 		DPRINTFN(3, ("uhid_intr: sending SIGIO %p\n", sc->sc_async));
    258 		mutex_enter(&proclist_mutex);
    259 		psignal(sc->sc_async, SIGIO);
    260 		mutex_exit(&proclist_mutex);
    261 	}
    262 }
    263 
    264 int
    265 uhidopen(dev_t dev, int flag, int mode,
    266     struct lwp *l)
    267 {
    268 	struct uhid_softc *sc;
    269 	int error;
    270 
    271 	USB_GET_SC_OPEN(uhid, UHIDUNIT(dev), sc);
    272 
    273 	DPRINTF(("uhidopen: sc=%p\n", sc));
    274 
    275 	if (sc->sc_dying)
    276 		return (ENXIO);
    277 
    278 	error = uhidev_open(&sc->sc_hdev);
    279 	if (error)
    280 		return (error);
    281 
    282 	if (clalloc(&sc->sc_q, UHID_BSIZE, 0) == -1) {
    283 		uhidev_close(&sc->sc_hdev);
    284 		return (ENOMEM);
    285 	}
    286 	sc->sc_obuf = malloc(sc->sc_osize, M_USBDEV, M_WAITOK);
    287 	sc->sc_state &= ~UHID_IMMED;
    288 	sc->sc_async = NULL;
    289 
    290 	return (0);
    291 }
    292 
    293 int
    294 uhidclose(dev_t dev, int flag, int mode,
    295     struct lwp *l)
    296 {
    297 	struct uhid_softc *sc;
    298 
    299 	USB_GET_SC(uhid, UHIDUNIT(dev), sc);
    300 
    301 	DPRINTF(("uhidclose: sc=%p\n", sc));
    302 
    303 	clfree(&sc->sc_q);
    304 	free(sc->sc_obuf, M_USBDEV);
    305 	sc->sc_async = NULL;
    306 	uhidev_close(&sc->sc_hdev);
    307 
    308 	return (0);
    309 }
    310 
    311 int
    312 uhid_do_read(struct uhid_softc *sc, struct uio *uio, int flag)
    313 {
    314 	int s;
    315 	int error = 0;
    316 	int extra;
    317 	size_t length;
    318 	u_char buffer[UHID_CHUNK];
    319 	usbd_status err;
    320 
    321 	DPRINTFN(1, ("uhidread\n"));
    322 	if (sc->sc_state & UHID_IMMED) {
    323 		DPRINTFN(1, ("uhidread immed\n"));
    324 		extra = sc->sc_hdev.sc_report_id != 0;
    325 		err = uhidev_get_report(&sc->sc_hdev, UHID_INPUT_REPORT,
    326 					buffer, sc->sc_isize + extra);
    327 		if (err)
    328 			return (EIO);
    329 		return (uiomove(buffer+extra, sc->sc_isize, uio));
    330 	}
    331 
    332 	s = splusb();
    333 	while (sc->sc_q.c_cc == 0) {
    334 		if (flag & IO_NDELAY) {
    335 			splx(s);
    336 			return (EWOULDBLOCK);
    337 		}
    338 		sc->sc_state |= UHID_ASLP;
    339 		DPRINTFN(5, ("uhidread: sleep on %p\n", &sc->sc_q));
    340 		error = tsleep(&sc->sc_q, PZERO | PCATCH, "uhidrea", 0);
    341 		DPRINTFN(5, ("uhidread: woke, error=%d\n", error));
    342 		if (sc->sc_dying)
    343 			error = EIO;
    344 		if (error) {
    345 			sc->sc_state &= ~UHID_ASLP;
    346 			break;
    347 		}
    348 	}
    349 	splx(s);
    350 
    351 	/* Transfer as many chunks as possible. */
    352 	while (sc->sc_q.c_cc > 0 && uio->uio_resid > 0 && !error) {
    353 		length = min(sc->sc_q.c_cc, uio->uio_resid);
    354 		if (length > sizeof(buffer))
    355 			length = sizeof(buffer);
    356 
    357 		/* Remove a small chunk from the input queue. */
    358 		(void) q_to_b(&sc->sc_q, buffer, length);
    359 		DPRINTFN(5, ("uhidread: got %lu chars\n", (u_long)length));
    360 
    361 		/* Copy the data to the user process. */
    362 		if ((error = uiomove(buffer, length, uio)) != 0)
    363 			break;
    364 	}
    365 
    366 	return (error);
    367 }
    368 
    369 int
    370 uhidread(dev_t dev, struct uio *uio, int flag)
    371 {
    372 	struct uhid_softc *sc;
    373 	int error;
    374 
    375 	USB_GET_SC(uhid, UHIDUNIT(dev), sc);
    376 
    377 	sc->sc_refcnt++;
    378 	error = uhid_do_read(sc, uio, flag);
    379 	if (--sc->sc_refcnt < 0)
    380 		usb_detach_wakeup(USBDEV(sc->sc_hdev.sc_dev));
    381 	return (error);
    382 }
    383 
    384 int
    385 uhid_do_write(struct uhid_softc *sc, struct uio *uio, int flag)
    386 {
    387 	int error;
    388 	int size;
    389 	usbd_status err;
    390 
    391 	DPRINTFN(1, ("uhidwrite\n"));
    392 
    393 	if (sc->sc_dying)
    394 		return (EIO);
    395 
    396 	size = sc->sc_osize;
    397 	error = 0;
    398 	if (uio->uio_resid != size)
    399 		return (EINVAL);
    400 	error = uiomove(sc->sc_obuf, size, uio);
    401 	if (!error) {
    402 		err = uhidev_set_report(&sc->sc_hdev, UHID_OUTPUT_REPORT,
    403 					sc->sc_obuf, size);
    404 		if (err)
    405 			error = EIO;
    406 	}
    407 
    408 	return (error);
    409 }
    410 
    411 int
    412 uhidwrite(dev_t dev, struct uio *uio, int flag)
    413 {
    414 	struct uhid_softc *sc;
    415 	int error;
    416 
    417 	USB_GET_SC(uhid, UHIDUNIT(dev), sc);
    418 
    419 	sc->sc_refcnt++;
    420 	error = uhid_do_write(sc, uio, flag);
    421 	if (--sc->sc_refcnt < 0)
    422 		usb_detach_wakeup(USBDEV(sc->sc_hdev.sc_dev));
    423 	return (error);
    424 }
    425 
    426 int
    427 uhid_do_ioctl(struct uhid_softc *sc, u_long cmd, void *addr,
    428     int flag, struct lwp *l)
    429 {
    430 	struct usb_ctl_report_desc *rd;
    431 	struct usb_ctl_report *re;
    432 	u_char buffer[UHID_CHUNK];
    433 	int size, extra;
    434 	usbd_status err;
    435 	void *desc;
    436 
    437 	DPRINTFN(2, ("uhidioctl: cmd=%lx\n", cmd));
    438 
    439 	if (sc->sc_dying)
    440 		return (EIO);
    441 
    442 	switch (cmd) {
    443 	case FIONBIO:
    444 		/* All handled in the upper FS layer. */
    445 		break;
    446 
    447 	case FIOASYNC:
    448 		if (*(int *)addr) {
    449 			if (sc->sc_async != NULL)
    450 				return (EBUSY);
    451 			sc->sc_async = l->l_proc;
    452 			DPRINTF(("uhid_do_ioctl: FIOASYNC %p\n", l->l_proc));
    453 		} else
    454 			sc->sc_async = NULL;
    455 		break;
    456 
    457 	/* XXX this is not the most general solution. */
    458 	case TIOCSPGRP:
    459 		if (sc->sc_async == NULL)
    460 			return (EINVAL);
    461 		if (*(int *)addr != sc->sc_async->p_pgid)
    462 			return (EPERM);
    463 		break;
    464 
    465 	case FIOSETOWN:
    466 		if (sc->sc_async == NULL)
    467 			return (EINVAL);
    468 		if (-*(int *)addr != sc->sc_async->p_pgid
    469 		    && *(int *)addr != sc->sc_async->p_pid)
    470 			return (EPERM);
    471 		break;
    472 
    473 	case USB_GET_REPORT_DESC:
    474 		uhidev_get_report_desc(sc->sc_hdev.sc_parent, &desc, &size);
    475 		rd = (struct usb_ctl_report_desc *)addr;
    476 		size = min(size, sizeof rd->ucrd_data);
    477 		rd->ucrd_size = size;
    478 		memcpy(rd->ucrd_data, desc, size);
    479 		break;
    480 
    481 	case USB_SET_IMMED:
    482 		if (*(int *)addr) {
    483 			extra = sc->sc_hdev.sc_report_id != 0;
    484 			err = uhidev_get_report(&sc->sc_hdev, UHID_INPUT_REPORT,
    485 						buffer, sc->sc_isize + extra);
    486 			if (err)
    487 				return (EOPNOTSUPP);
    488 
    489 			sc->sc_state |=  UHID_IMMED;
    490 		} else
    491 			sc->sc_state &= ~UHID_IMMED;
    492 		break;
    493 
    494 	case USB_GET_REPORT:
    495 		re = (struct usb_ctl_report *)addr;
    496 		switch (re->ucr_report) {
    497 		case UHID_INPUT_REPORT:
    498 			size = sc->sc_isize;
    499 			break;
    500 		case UHID_OUTPUT_REPORT:
    501 			size = sc->sc_osize;
    502 			break;
    503 		case UHID_FEATURE_REPORT:
    504 			size = sc->sc_fsize;
    505 			break;
    506 		default:
    507 			return (EINVAL);
    508 		}
    509 		extra = sc->sc_hdev.sc_report_id != 0;
    510 		err = uhidev_get_report(&sc->sc_hdev, re->ucr_report,
    511 		    re->ucr_data, size + extra);
    512 		if (extra)
    513 			memcpy(re->ucr_data, re->ucr_data+1, size);
    514 		if (err)
    515 			return (EIO);
    516 		break;
    517 
    518 	case USB_SET_REPORT:
    519 		re = (struct usb_ctl_report *)addr;
    520 		switch (re->ucr_report) {
    521 		case UHID_INPUT_REPORT:
    522 			size = sc->sc_isize;
    523 			break;
    524 		case UHID_OUTPUT_REPORT:
    525 			size = sc->sc_osize;
    526 			break;
    527 		case UHID_FEATURE_REPORT:
    528 			size = sc->sc_fsize;
    529 			break;
    530 		default:
    531 			return (EINVAL);
    532 		}
    533 		err = uhidev_set_report(&sc->sc_hdev, re->ucr_report,
    534 		    re->ucr_data, size);
    535 		if (err)
    536 			return (EIO);
    537 		break;
    538 
    539 	case USB_GET_REPORT_ID:
    540 		*(int *)addr = sc->sc_hdev.sc_report_id;
    541 		break;
    542 
    543 	case USB_GET_DEVICEINFO:
    544 		usbd_fill_deviceinfo(sc->sc_hdev.sc_parent->sc_udev,
    545 			             (struct usb_device_info *)addr, 0);
    546 		break;
    547 #ifdef COMPAT_30
    548 	case USB_GET_DEVICEINFO_OLD:
    549 		usbd_fill_deviceinfo_old(sc->sc_hdev.sc_parent->sc_udev,
    550 					 (struct usb_device_info_old *)addr, 0);
    551 
    552 		break;
    553 #endif
    554         case USB_GET_STRING_DESC:
    555 	    {
    556                 struct usb_string_desc *si = (struct usb_string_desc *)addr;
    557                 err = usbd_get_string_desc(sc->sc_hdev.sc_parent->sc_udev,
    558 			si->usd_string_index,
    559                 	si->usd_language_id, &si->usd_desc, &size);
    560                 if (err)
    561                         return (EINVAL);
    562                 break;
    563 	    }
    564 
    565 	default:
    566 		return (EINVAL);
    567 	}
    568 	return (0);
    569 }
    570 
    571 int
    572 uhidioctl(dev_t dev, u_long cmd, void *addr, int flag, struct lwp *l)
    573 {
    574 	struct uhid_softc *sc;
    575 	int error;
    576 
    577 	USB_GET_SC(uhid, UHIDUNIT(dev), sc);
    578 
    579 	sc->sc_refcnt++;
    580 	error = uhid_do_ioctl(sc, cmd, addr, flag, l);
    581 	if (--sc->sc_refcnt < 0)
    582 		usb_detach_wakeup(USBDEV(sc->sc_hdev.sc_dev));
    583 	return (error);
    584 }
    585 
    586 int
    587 uhidpoll(dev_t dev, int events, struct lwp *l)
    588 {
    589 	struct uhid_softc *sc;
    590 	int revents = 0;
    591 	int s;
    592 
    593 	USB_GET_SC(uhid, UHIDUNIT(dev), sc);
    594 
    595 	if (sc->sc_dying)
    596 		return (POLLHUP);
    597 
    598 	s = splusb();
    599 	if (events & (POLLOUT | POLLWRNORM))
    600 		revents |= events & (POLLOUT | POLLWRNORM);
    601 	if (events & (POLLIN | POLLRDNORM)) {
    602 		if (sc->sc_q.c_cc > 0)
    603 			revents |= events & (POLLIN | POLLRDNORM);
    604 		else
    605 			selrecord(l, &sc->sc_rsel);
    606 	}
    607 
    608 	splx(s);
    609 	return (revents);
    610 }
    611 
    612 static void
    613 filt_uhidrdetach(struct knote *kn)
    614 {
    615 	struct uhid_softc *sc = kn->kn_hook;
    616 	int s;
    617 
    618 	s = splusb();
    619 	SLIST_REMOVE(&sc->sc_rsel.sel_klist, kn, knote, kn_selnext);
    620 	splx(s);
    621 }
    622 
    623 static int
    624 filt_uhidread(struct knote *kn, long hint)
    625 {
    626 	struct uhid_softc *sc = kn->kn_hook;
    627 
    628 	kn->kn_data = sc->sc_q.c_cc;
    629 	return (kn->kn_data > 0);
    630 }
    631 
    632 static const struct filterops uhidread_filtops =
    633 	{ 1, NULL, filt_uhidrdetach, filt_uhidread };
    634 
    635 static const struct filterops uhid_seltrue_filtops =
    636 	{ 1, NULL, filt_uhidrdetach, filt_seltrue };
    637 
    638 int
    639 uhidkqfilter(dev_t dev, struct knote *kn)
    640 {
    641 	struct uhid_softc *sc;
    642 	struct klist *klist;
    643 	int s;
    644 
    645 	USB_GET_SC(uhid, UHIDUNIT(dev), sc);
    646 
    647 	if (sc->sc_dying)
    648 		return (ENXIO);
    649 
    650 	switch (kn->kn_filter) {
    651 	case EVFILT_READ:
    652 		klist = &sc->sc_rsel.sel_klist;
    653 		kn->kn_fop = &uhidread_filtops;
    654 		break;
    655 
    656 	case EVFILT_WRITE:
    657 		klist = &sc->sc_rsel.sel_klist;
    658 		kn->kn_fop = &uhid_seltrue_filtops;
    659 		break;
    660 
    661 	default:
    662 		return (EINVAL);
    663 	}
    664 
    665 	kn->kn_hook = sc;
    666 
    667 	s = splusb();
    668 	SLIST_INSERT_HEAD(klist, kn, kn_selnext);
    669 	splx(s);
    670 
    671 	return (0);
    672 }
    673