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button.c revision 1.13 
      1 /*	$NetBSD: button.c,v 1.13 2021/09/26 14:32:02 thorpej Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2003 Wasabi Systems, Inc.
      5  * All rights reserved.
      6  *
      7  * Written by Jason R. Thorpe for Wasabi Systems, Inc.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  * 3. All advertising materials mentioning features or use of this software
     18  *    must display the following acknowledgement:
     19  *	This product includes software developed for the NetBSD Project by
     20  *	Wasabi Systems, Inc.
     21  * 4. The name of Wasabi Systems, Inc. may not be used to endorse
     22  *    or promote products derived from this software without specific prior
     23  *    written permission.
     24  *
     25  * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
     26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     27  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     28  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL WASABI SYSTEMS, INC
     29  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     30  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     31  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     32  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     33  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     34  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     35  * POSSIBILITY OF SUCH DAMAGE.
     36  */
     37 
     38 #include <sys/cdefs.h>
     39 __KERNEL_RCSID(0, "$NetBSD: button.c,v 1.13 2021/09/26 14:32:02 thorpej Exp $");
     40 
     41 #include <sys/param.h>
     42 #include <sys/conf.h>
     43 #include <sys/systm.h>
     44 #include <sys/queue.h>
     45 #include <sys/mutex.h>
     46 #include <sys/errno.h>
     47 #include <sys/fcntl.h>
     48 #include <sys/callout.h>
     49 #include <sys/kernel.h>
     50 #include <sys/once.h>
     51 #include <sys/poll.h>
     52 #include <sys/select.h>
     53 #include <sys/vnode.h>
     54 
     55 #include <machine/button.h>
     56 
     57 #include <landisk/dev/buttonvar.h>
     58 
     59 /*
     60  * event handler
     61  */
     62 static LIST_HEAD(, btn_event) btn_event_list;
     63 static kmutex_t btn_event_list_lock;
     64 
     65 static struct lwp *btn_daemon;
     66 
     67 #define	BTN_MAX_EVENTS		32
     68 
     69 static kmutex_t btn_event_queue_lock;
     70 static kcondvar_t btn_event_queue_cv;
     71 
     72 static button_event_t btn_event_queue[BTN_MAX_EVENTS];
     73 static int btn_event_queue_head;
     74 static int btn_event_queue_tail;
     75 static int btn_event_queue_count;
     76 static int btn_event_queue_flags;
     77 static struct selinfo btn_event_queue_selinfo;
     78 
     79 static char btn_type[32];
     80 
     81 #define	BEVQ_F_WAITING		0x01	/* daemon waiting for event */
     82 
     83 #define	BTN_NEXT_EVENT(x)	(((x) + 1) / BTN_MAX_EVENTS)
     84 
     85 dev_type_open(btnopen);
     86 dev_type_close(btnclose);
     87 dev_type_ioctl(btnioctl);
     88 dev_type_read(btnread);
     89 dev_type_poll(btnpoll);
     90 dev_type_kqfilter(btnkqfilter);
     91 
     92 const struct cdevsw button_cdevsw = {
     93 	.d_open = btnopen,
     94 	.d_close = btnclose,
     95 	.d_read = btnread,
     96 	.d_write = nowrite,
     97 	.d_ioctl = btnioctl,
     98 	.d_stop = nostop,
     99 	.d_tty = notty,
    100 	.d_poll = btnpoll,
    101 	.d_mmap = nommap,
    102 	.d_kqfilter = btnkqfilter,
    103 	.d_discard = nodiscard,
    104 	.d_flag = 0
    105 };
    106 
    107 int
    108 btn_init(void)
    109 {
    110 
    111 	LIST_INIT(&btn_event_list);
    112 	mutex_init(&btn_event_list_lock, MUTEX_DEFAULT, IPL_NONE);
    113 	mutex_init(&btn_event_queue_lock, MUTEX_DEFAULT, IPL_NONE);
    114 	cv_init(&btn_event_queue_cv, "btncv");
    115 	selinit(&btn_event_queue_selinfo);
    116 
    117 	return 0;
    118 }
    119 
    120 static int
    121 btn_queue_event(button_event_t *bev)
    122 {
    123 
    124 	if (btn_event_queue_count == BTN_MAX_EVENTS)
    125 		return (0);
    126 
    127 	btn_event_queue[btn_event_queue_head] = *bev;
    128 	btn_event_queue_head = BTN_NEXT_EVENT(btn_event_queue_head);
    129 	btn_event_queue_count++;
    130 
    131 	return (1);
    132 }
    133 
    134 static int
    135 btn_get_event(button_event_t *bev)
    136 {
    137 
    138 	if (btn_event_queue_count == 0)
    139 		return (0);
    140 
    141 	*bev = btn_event_queue[btn_event_queue_tail];
    142 	btn_event_queue_tail = BTN_NEXT_EVENT(btn_event_queue_tail);
    143 	btn_event_queue_count--;
    144 
    145 	return (1);
    146 }
    147 
    148 static void
    149 btn_event_queue_flush(void)
    150 {
    151 
    152 	btn_event_queue_head = 0;
    153 	btn_event_queue_tail = 0;
    154 	btn_event_queue_count = 0;
    155 	btn_event_queue_flags = 0;
    156 }
    157 
    158 int
    159 btnopen(dev_t dev, int flag, int mode, struct lwp *l)
    160 {
    161 	int error;
    162 
    163 	if (minor(dev) != 0) {
    164 		return (ENODEV);
    165 	}
    166 
    167 	mutex_enter(&btn_event_queue_lock);
    168 	if (btn_daemon != NULL) {
    169 		error = EBUSY;
    170 	} else {
    171 		error = 0;
    172 		btn_daemon = l;
    173 		btn_event_queue_flush();
    174 	}
    175 	mutex_exit(&btn_event_queue_lock);
    176 
    177 	return (error);
    178 }
    179 
    180 int
    181 btnclose(dev_t dev, int flag, int mode, struct lwp *l)
    182 {
    183 	int count;
    184 
    185 	if (minor(dev) != 0) {
    186 		return (ENODEV);
    187 	}
    188 
    189 	mutex_enter(&btn_event_queue_lock);
    190 	count = btn_event_queue_count;
    191 	btn_daemon = NULL;
    192 	btn_event_queue_flush();
    193 	mutex_exit(&btn_event_queue_lock);
    194 
    195 	if (count) {
    196 		printf("WARNING: %d events lost by exiting daemon\n", count);
    197 	}
    198 
    199 	return (0);
    200 }
    201 
    202 int
    203 btnioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
    204 {
    205 	int error = 0;
    206 
    207 	if (minor(dev) != 0) {
    208 		return (ENODEV);
    209 	}
    210 
    211 	switch (cmd) {
    212 	case BUTTON_IOC_GET_TYPE:
    213 	    {
    214 		struct button_type *button_type = (void *)data;
    215 		strcpy(button_type->button_type, btn_type);
    216 		break;
    217 	    }
    218 
    219 	default:
    220 		error = ENOTTY;
    221 		break;
    222 	}
    223 
    224 	return (error);
    225 }
    226 
    227 int
    228 btnread(dev_t dev, struct uio *uio, int flags)
    229 {
    230 	button_event_t bev;
    231 	int error;
    232 
    233 	if (minor(dev) != 0) {
    234 		return (ENODEV);
    235 	}
    236 
    237 	if (uio->uio_resid != BUTTON_EVENT_MSG_SIZE) {
    238 		return (EINVAL);
    239 	}
    240 
    241 	mutex_enter(&btn_event_queue_lock);
    242 	for (;;) {
    243 		if (btn_get_event(&bev)) {
    244 			mutex_exit(&btn_event_queue_lock);
    245 			return (uiomove(&bev, BUTTON_EVENT_MSG_SIZE, uio));
    246 		}
    247 
    248 		if (flags & IO_NDELAY) {
    249 			mutex_exit(&btn_event_queue_lock);
    250 			return (EWOULDBLOCK);
    251 		}
    252 
    253 		btn_event_queue_flags |= BEVQ_F_WAITING;
    254 		error = cv_wait_sig(&btn_event_queue_cv, &btn_event_queue_lock);
    255 		if (error) {
    256 			mutex_exit(&btn_event_queue_lock);
    257 			return (error);
    258 		}
    259 	}
    260 }
    261 
    262 int
    263 btnpoll(dev_t dev, int events, struct lwp *l)
    264 {
    265 	int revents;
    266 
    267 	if (minor(dev) != 0) {
    268 		return (ENODEV);
    269 	}
    270 
    271 	revents = events & (POLLOUT | POLLWRNORM);
    272 
    273 	/* Attempt to save some work. */
    274 	if ((events & (POLLIN | POLLRDNORM)) == 0)
    275 		return (revents);
    276 
    277 	mutex_enter(&btn_event_queue_lock);
    278 	if (btn_event_queue_count) {
    279 		revents |= events & (POLLIN | POLLRDNORM);
    280 	} else {
    281 		selrecord(l, &btn_event_queue_selinfo);
    282 	}
    283 	mutex_exit(&btn_event_queue_lock);
    284 
    285 	return (revents);
    286 }
    287 
    288 static void
    289 filt_btn_rdetach(struct knote *kn)
    290 {
    291 
    292 	mutex_enter(&btn_event_queue_lock);
    293 	selremove_knote(&btn_event_queue_selinfo, kn);
    294 	mutex_exit(&btn_event_queue_lock);
    295 }
    296 
    297 static int
    298 filt_btn_read(struct knote *kn, long hint)
    299 {
    300 
    301 	mutex_enter(&btn_event_queue_lock);
    302 	kn->kn_data = btn_event_queue_count;
    303 	mutex_exit(&btn_event_queue_lock);
    304 
    305 	return (kn->kn_data > 0);
    306 }
    307 
    308 static const struct filterops btn_read_filtops = {
    309     .f_flags = FILTEROP_ISFD,
    310     .f_attach = NULL,
    311     .f_detach = filt_btn_rdetach,
    312     .f_event = filt_btn_read,
    313 };
    314 
    315 int
    316 btnkqfilter(dev_t dev, struct knote *kn)
    317 {
    318 
    319 	if (minor(dev) != 0) {
    320 		return (ENODEV);
    321 	}
    322 
    323 	switch (kn->kn_filter) {
    324 	case EVFILT_READ:
    325 		kn->kn_fop = &btn_read_filtops;
    326 		mutex_enter(&btn_event_queue_lock);
    327 		selrecord_knote(&btn_event_queue_selinfo, kn);
    328 		mutex_exit(&btn_event_queue_lock);
    329 		break;
    330 
    331 	case EVFILT_WRITE:
    332 		kn->kn_fop = &seltrue_filtops;
    333 		break;
    334 
    335 	default:
    336 		return (1);
    337 	}
    338 
    339 	return (0);
    340 }
    341 
    342 void
    343 btn_settype(const char *type)
    344 {
    345 
    346 	/*
    347 	 * Don't bother locking this; it's going to be set
    348 	 * during autoconfiguration, and then only read from
    349 	 * then on.
    350 	 */
    351 	strlcpy(btn_type, type, sizeof(btn_type));
    352 }
    353 
    354 int
    355 btn_event_register(struct btn_event *bev)
    356 {
    357 
    358 	mutex_enter(&btn_event_list_lock);
    359 	LIST_INSERT_HEAD(&btn_event_list, bev, bev_list);
    360 	mutex_exit(&btn_event_list_lock);
    361 
    362 	return (0);
    363 }
    364 
    365 void
    366 btn_event_unregister(struct btn_event *bev)
    367 {
    368 
    369 	mutex_enter(&btn_event_list_lock);
    370 	LIST_REMOVE(bev, bev_list);
    371 	mutex_exit(&btn_event_list_lock);
    372 }
    373 
    374 void
    375 btn_event_send(struct btn_event *bev, int event)
    376 {
    377 	button_event_t btnev;
    378 	int rv;
    379 
    380 	mutex_enter(&btn_event_queue_lock);
    381 	if (btn_daemon == NULL) {
    382 		mutex_exit(&btn_event_queue_lock);
    383 		printf("%s: btn_event_send can't handle me.\n", bev->bev_name);
    384 		return;
    385 	}
    386 
    387 	btnev.bev_type = BUTTON_EVENT_STATE_CHANGE;
    388 	btnev.bev_event.bs_state = event;
    389 	strcpy(btnev.bev_event.bs_name, bev->bev_name);
    390 
    391 	rv = btn_queue_event(&btnev);
    392 	if (rv == 0) {
    393 		mutex_exit(&btn_event_queue_lock);
    394 		printf("%s: WARNING: state change event %d lost; "
    395 		    "queue full\n", bev->bev_name, btnev.bev_type);
    396 		return;
    397 	}
    398 	if (btn_event_queue_flags & BEVQ_F_WAITING) {
    399 		btn_event_queue_flags &= ~BEVQ_F_WAITING;
    400 		cv_broadcast(&btn_event_queue_cv);
    401 	}
    402 	selnotify(&btn_event_queue_selinfo, 0, 0);
    403 	mutex_exit(&btn_event_queue_lock);
    404 }
    405