kern_et.c revision 248230 
1/*-
2 * Copyright (c) 2010-2013 Alexander Motin <mav@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer,
10 *    without modification, immediately at the beginning of the file.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/sys/kern/kern_et.c 248230 2013-03-13 06:42:01Z mav $");
29
30#include <sys/param.h>
31#include <sys/kernel.h>
32#include <sys/sysctl.h>
33#include <sys/systm.h>
34#include <sys/queue.h>
35#include <sys/timeet.h>
36
37SLIST_HEAD(et_eventtimers_list, eventtimer);
38static struct et_eventtimers_list eventtimers = SLIST_HEAD_INITIALIZER(et_eventtimers);
39
40struct mtx	et_eventtimers_mtx;
41MTX_SYSINIT(et_eventtimers_init, &et_eventtimers_mtx, "et_mtx", MTX_DEF);
42
43SYSCTL_NODE(_kern, OID_AUTO, eventtimer, CTLFLAG_RW, 0, "Event timers");
44static SYSCTL_NODE(_kern_eventtimer, OID_AUTO, et, CTLFLAG_RW, 0, "");
45
46/*
47 * Register a new event timer hardware.
48 */
49int
50et_register(struct eventtimer *et)
51{
52	struct eventtimer *tmp, *next;
53
54	if (et->et_quality >= 0 || bootverbose) {
55		if (et->et_frequency == 0) {
56			printf("Event timer \"%s\" quality %d\n",
57			    et->et_name, et->et_quality);
58		} else {
59			printf("Event timer \"%s\" "
60			    "frequency %ju Hz quality %d\n",
61			    et->et_name, (uintmax_t)et->et_frequency,
62			    et->et_quality);
63		}
64	}
65	KASSERT(et->et_start, ("et_register: timer has no start function"));
66	et->et_sysctl = SYSCTL_ADD_NODE(NULL,
67	    SYSCTL_STATIC_CHILDREN(_kern_eventtimer_et), OID_AUTO, et->et_name,
68	    CTLFLAG_RW, 0, "event timer description");
69	SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(et->et_sysctl), OID_AUTO,
70	    "flags", CTLFLAG_RD, &(et->et_flags), 0,
71	    "Event timer capabilities");
72	SYSCTL_ADD_UQUAD(NULL, SYSCTL_CHILDREN(et->et_sysctl), OID_AUTO,
73	    "frequency", CTLFLAG_RD, &(et->et_frequency),
74	    "Event timer base frequency");
75	SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(et->et_sysctl), OID_AUTO,
76	    "quality", CTLFLAG_RD, &(et->et_quality), 0,
77	    "Goodness of event timer");
78	ET_LOCK();
79	if (SLIST_EMPTY(&eventtimers) ||
80	    SLIST_FIRST(&eventtimers)->et_quality < et->et_quality) {
81		SLIST_INSERT_HEAD(&eventtimers, et, et_all);
82	} else {
83		SLIST_FOREACH(tmp, &eventtimers, et_all) {
84			next = SLIST_NEXT(tmp, et_all);
85			if (next == NULL || next->et_quality < et->et_quality) {
86				SLIST_INSERT_AFTER(tmp, et, et_all);
87				break;
88			}
89		}
90	}
91	ET_UNLOCK();
92	return (0);
93}
94
95/*
96 * Deregister event timer hardware.
97 */
98int
99et_deregister(struct eventtimer *et)
100{
101	int err = 0;
102
103	if (et->et_deregister_cb != NULL) {
104		if ((err = et->et_deregister_cb(et, et->et_arg)) != 0)
105			return (err);
106	}
107
108	ET_LOCK();
109	SLIST_REMOVE(&eventtimers, et, eventtimer, et_all);
110	ET_UNLOCK();
111	sysctl_remove_oid(et->et_sysctl, 1, 1);
112	return (0);
113}
114
115/*
116 * Find free event timer hardware with specified parameters.
117 */
118struct eventtimer *
119et_find(const char *name, int check, int want)
120{
121	struct eventtimer *et = NULL;
122
123	SLIST_FOREACH(et, &eventtimers, et_all) {
124		if (et->et_active)
125			continue;
126		if (name != NULL && strcasecmp(et->et_name, name) != 0)
127			continue;
128		if (name == NULL && et->et_quality < 0)
129			continue;
130		if ((et->et_flags & check) != want)
131			continue;
132		break;
133	}
134	return (et);
135}
136
137/*
138 * Initialize event timer hardware. Set callbacks.
139 */
140int
141et_init(struct eventtimer *et, et_event_cb_t *event,
142    et_deregister_cb_t *deregister, void *arg)
143{
144
145	if (event == NULL)
146		return (EINVAL);
147	if (et->et_active)
148		return (EBUSY);
149
150	et->et_active = 1;
151	et->et_event_cb = event;
152	et->et_deregister_cb = deregister;
153	et->et_arg = arg;
154	return (0);
155}
156
157/*
158 * Start event timer hardware.
159 * first - delay before first tick.
160 * period - period of subsequent periodic ticks.
161 */
162int
163et_start(struct eventtimer *et, sbintime_t first, sbintime_t period)
164{
165
166	if (!et->et_active)
167		return (ENXIO);
168	KASSERT(period >= 0, ("et_start: negative period"));
169	KASSERT((et->et_flags & ET_FLAGS_PERIODIC) || period == 0,
170		("et_start: period specified for oneshot-only timer"));
171	KASSERT((et->et_flags & ET_FLAGS_ONESHOT) || period != 0,
172		("et_start: period not specified for periodic-only timer"));
173	if (period != 0) {
174		if (period < et->et_min_period)
175		        period = et->et_min_period;
176		else if (period > et->et_max_period)
177		        period = et->et_max_period;
178	}
179	if (period == 0 || first != 0) {
180		if (first < et->et_min_period)
181		        first = et->et_min_period;
182		else if (first > et->et_max_period)
183		        first = et->et_max_period;
184	}
185	return (et->et_start(et, first, period));
186}
187
188/* Stop event timer hardware. */
189int
190et_stop(struct eventtimer *et)
191{
192
193	if (!et->et_active)
194		return (ENXIO);
195	if (et->et_stop)
196		return (et->et_stop(et));
197	return (0);
198}
199
200/* Mark event timer hardware as broken. */
201int
202et_ban(struct eventtimer *et)
203{
204
205	et->et_flags &= ~(ET_FLAGS_PERIODIC | ET_FLAGS_ONESHOT);
206	return (0);
207}
208
209/* Free event timer hardware. */
210int
211et_free(struct eventtimer *et)
212{
213
214	if (!et->et_active)
215		return (ENXIO);
216
217	et->et_active = 0;
218	return (0);
219}
220
221/* Report list of supported event timers hardware via sysctl. */
222static int
223sysctl_kern_eventtimer_choice(SYSCTL_HANDLER_ARGS)
224{
225	char buf[512], *spc;
226	struct eventtimer *et;
227	int error, off;
228
229	spc = "";
230	error = 0;
231	buf[0] = 0;
232	off = 0;
233	ET_LOCK();
234	SLIST_FOREACH(et, &eventtimers, et_all) {
235		off += snprintf(buf + off, sizeof(buf) - off, "%s%s(%d)",
236		    spc, et->et_name, et->et_quality);
237		spc = " ";
238	}
239	ET_UNLOCK();
240	error = SYSCTL_OUT(req, buf, strlen(buf));
241	return (error);
242}
243SYSCTL_PROC(_kern_eventtimer, OID_AUTO, choice,
244    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
245    0, 0, sysctl_kern_eventtimer_choice, "A", "Present event timers");
246
247