kern_et.c revision 266347 
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: stable/10/sys/kern/kern_et.c 266347 2014-05-17 20:10:12Z ian $");
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
37#include "opt_timer.h"
38
39SLIST_HEAD(et_eventtimers_list, eventtimer);
40static struct et_eventtimers_list eventtimers = SLIST_HEAD_INITIALIZER(et_eventtimers);
41
42struct mtx	et_eventtimers_mtx;
43MTX_SYSINIT(et_eventtimers_init, &et_eventtimers_mtx, "et_mtx", MTX_DEF);
44
45SYSCTL_NODE(_kern, OID_AUTO, eventtimer, CTLFLAG_RW, 0, "Event timers");
46static SYSCTL_NODE(_kern_eventtimer, OID_AUTO, et, CTLFLAG_RW, 0, "");
47
48/*
49 * Register a new event timer hardware.
50 */
51int
52et_register(struct eventtimer *et)
53{
54	struct eventtimer *tmp, *next;
55
56	if (et->et_quality >= 0 || bootverbose) {
57		if (et->et_frequency == 0) {
58			printf("Event timer \"%s\" quality %d\n",
59			    et->et_name, et->et_quality);
60		} else {
61			printf("Event timer \"%s\" "
62			    "frequency %ju Hz quality %d\n",
63			    et->et_name, (uintmax_t)et->et_frequency,
64			    et->et_quality);
65		}
66	}
67	KASSERT(et->et_start, ("et_register: timer has no start function"));
68	et->et_sysctl = SYSCTL_ADD_NODE(NULL,
69	    SYSCTL_STATIC_CHILDREN(_kern_eventtimer_et), OID_AUTO, et->et_name,
70	    CTLFLAG_RW, 0, "event timer description");
71	SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(et->et_sysctl), OID_AUTO,
72	    "flags", CTLFLAG_RD, &(et->et_flags), 0,
73	    "Event timer capabilities");
74	SYSCTL_ADD_UQUAD(NULL, SYSCTL_CHILDREN(et->et_sysctl), OID_AUTO,
75	    "frequency", CTLFLAG_RD, &(et->et_frequency),
76	    "Event timer base frequency");
77	SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(et->et_sysctl), OID_AUTO,
78	    "quality", CTLFLAG_RD, &(et->et_quality), 0,
79	    "Goodness of event timer");
80	ET_LOCK();
81	if (SLIST_EMPTY(&eventtimers) ||
82	    SLIST_FIRST(&eventtimers)->et_quality < et->et_quality) {
83		SLIST_INSERT_HEAD(&eventtimers, et, et_all);
84	} else {
85		SLIST_FOREACH(tmp, &eventtimers, et_all) {
86			next = SLIST_NEXT(tmp, et_all);
87			if (next == NULL || next->et_quality < et->et_quality) {
88				SLIST_INSERT_AFTER(tmp, et, et_all);
89				break;
90			}
91		}
92	}
93	ET_UNLOCK();
94	return (0);
95}
96
97/*
98 * Deregister event timer hardware.
99 */
100int
101et_deregister(struct eventtimer *et)
102{
103	int err = 0;
104
105	if (et->et_deregister_cb != NULL) {
106		if ((err = et->et_deregister_cb(et, et->et_arg)) != 0)
107			return (err);
108	}
109
110	ET_LOCK();
111	SLIST_REMOVE(&eventtimers, et, eventtimer, et_all);
112	ET_UNLOCK();
113	sysctl_remove_oid(et->et_sysctl, 1, 1);
114	return (0);
115}
116
117/*
118 * Change the frequency of the given timer.  If it is the active timer,
119 * reconfigure it on all CPUs (reschedules all current events based on the new
120 * timer frequency).
121 */
122void
123et_change_frequency(struct eventtimer *et, uint64_t newfreq)
124{
125
126#ifndef NO_EVENTTIMERS
127	cpu_et_frequency(et, newfreq);
128#endif
129}
130
131/*
132 * Find free event timer hardware with specified parameters.
133 */
134struct eventtimer *
135et_find(const char *name, int check, int want)
136{
137	struct eventtimer *et = NULL;
138
139	SLIST_FOREACH(et, &eventtimers, et_all) {
140		if (et->et_active)
141			continue;
142		if (name != NULL && strcasecmp(et->et_name, name) != 0)
143			continue;
144		if (name == NULL && et->et_quality < 0)
145			continue;
146		if ((et->et_flags & check) != want)
147			continue;
148		break;
149	}
150	return (et);
151}
152
153/*
154 * Initialize event timer hardware. Set callbacks.
155 */
156int
157et_init(struct eventtimer *et, et_event_cb_t *event,
158    et_deregister_cb_t *deregister, void *arg)
159{
160
161	if (event == NULL)
162		return (EINVAL);
163	if (et->et_active)
164		return (EBUSY);
165
166	et->et_active = 1;
167	et->et_event_cb = event;
168	et->et_deregister_cb = deregister;
169	et->et_arg = arg;
170	return (0);
171}
172
173/*
174 * Start event timer hardware.
175 * first - delay before first tick.
176 * period - period of subsequent periodic ticks.
177 */
178int
179et_start(struct eventtimer *et, sbintime_t first, sbintime_t period)
180{
181
182	if (!et->et_active)
183		return (ENXIO);
184	KASSERT(period >= 0, ("et_start: negative period"));
185	KASSERT((et->et_flags & ET_FLAGS_PERIODIC) || period == 0,
186		("et_start: period specified for oneshot-only timer"));
187	KASSERT((et->et_flags & ET_FLAGS_ONESHOT) || period != 0,
188		("et_start: period not specified for periodic-only timer"));
189	if (period != 0) {
190		if (period < et->et_min_period)
191		        period = et->et_min_period;
192		else if (period > et->et_max_period)
193		        period = et->et_max_period;
194	}
195	if (period == 0 || first != 0) {
196		if (first < et->et_min_period)
197		        first = et->et_min_period;
198		else if (first > et->et_max_period)
199		        first = et->et_max_period;
200	}
201	return (et->et_start(et, first, period));
202}
203
204/* Stop event timer hardware. */
205int
206et_stop(struct eventtimer *et)
207{
208
209	if (!et->et_active)
210		return (ENXIO);
211	if (et->et_stop)
212		return (et->et_stop(et));
213	return (0);
214}
215
216/* Mark event timer hardware as broken. */
217int
218et_ban(struct eventtimer *et)
219{
220
221	et->et_flags &= ~(ET_FLAGS_PERIODIC | ET_FLAGS_ONESHOT);
222	return (0);
223}
224
225/* Free event timer hardware. */
226int
227et_free(struct eventtimer *et)
228{
229
230	if (!et->et_active)
231		return (ENXIO);
232
233	et->et_active = 0;
234	return (0);
235}
236
237/* Report list of supported event timers hardware via sysctl. */
238static int
239sysctl_kern_eventtimer_choice(SYSCTL_HANDLER_ARGS)
240{
241	char buf[512], *spc;
242	struct eventtimer *et;
243	int error, off;
244
245	spc = "";
246	error = 0;
247	buf[0] = 0;
248	off = 0;
249	ET_LOCK();
250	SLIST_FOREACH(et, &eventtimers, et_all) {
251		off += snprintf(buf + off, sizeof(buf) - off, "%s%s(%d)",
252		    spc, et->et_name, et->et_quality);
253		spc = " ";
254	}
255	ET_UNLOCK();
256	error = SYSCTL_OUT(req, buf, strlen(buf));
257	return (error);
258}
259SYSCTL_PROC(_kern_eventtimer, OID_AUTO, choice,
260    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
261    0, 0, sysctl_kern_eventtimer_choice, "A", "Present event timers");
262
263