FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_et.c
1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2010-2013 Alexander Motin <mav@FreeBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer,
12 * without modification, immediately at the beginning of the file.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31
32 #include <sys/param.h>
33 #include <sys/kernel.h>
34 #include <sys/sbuf.h>
35 #include <sys/sysctl.h>
36 #include <sys/systm.h>
37 #include <sys/queue.h>
38 #include <sys/timeet.h>
39
40 #include "opt_timer.h"
41
42 SLIST_HEAD(et_eventtimers_list, eventtimer);
43 static struct et_eventtimers_list eventtimers = SLIST_HEAD_INITIALIZER(et_eventtimers);
44
45 struct mtx et_eventtimers_mtx;
46 MTX_SYSINIT(et_eventtimers_init, &et_eventtimers_mtx, "et_mtx", MTX_DEF);
47
48 SYSCTL_NODE(_kern, OID_AUTO, eventtimer, CTLFLAG_RW, 0, "Event timers");
49 static SYSCTL_NODE(_kern_eventtimer, OID_AUTO, et, CTLFLAG_RW, 0, "");
50
51 /*
52 * Register a new event timer hardware.
53 */
54 int
55 et_register(struct eventtimer *et)
56 {
57 struct eventtimer *tmp, *next;
58
59 if (et->et_quality >= 0 || bootverbose) {
60 if (et->et_frequency == 0) {
61 printf("Event timer \"%s\" quality %d\n",
62 et->et_name, et->et_quality);
63 } else {
64 printf("Event timer \"%s\" "
65 "frequency %ju Hz quality %d\n",
66 et->et_name, (uintmax_t)et->et_frequency,
67 et->et_quality);
68 }
69 }
70 KASSERT(et->et_start, ("et_register: timer has no start function"));
71 et->et_sysctl = SYSCTL_ADD_NODE_WITH_LABEL(NULL,
72 SYSCTL_STATIC_CHILDREN(_kern_eventtimer_et), OID_AUTO, et->et_name,
73 CTLFLAG_RW, 0, "event timer description", "eventtimer");
74 SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(et->et_sysctl), OID_AUTO,
75 "flags", CTLFLAG_RD, &(et->et_flags), 0,
76 "Event timer capabilities");
77 SYSCTL_ADD_UQUAD(NULL, SYSCTL_CHILDREN(et->et_sysctl), OID_AUTO,
78 "frequency", CTLFLAG_RD, &(et->et_frequency),
79 "Event timer base frequency");
80 SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(et->et_sysctl), OID_AUTO,
81 "quality", CTLFLAG_RD, &(et->et_quality), 0,
82 "Goodness of event timer");
83 ET_LOCK();
84 if (SLIST_EMPTY(&eventtimers) ||
85 SLIST_FIRST(&eventtimers)->et_quality < et->et_quality) {
86 SLIST_INSERT_HEAD(&eventtimers, et, et_all);
87 } else {
88 SLIST_FOREACH(tmp, &eventtimers, et_all) {
89 next = SLIST_NEXT(tmp, et_all);
90 if (next == NULL || next->et_quality < et->et_quality) {
91 SLIST_INSERT_AFTER(tmp, et, et_all);
92 break;
93 }
94 }
95 }
96 ET_UNLOCK();
97 return (0);
98 }
99
100 /*
101 * Deregister event timer hardware.
102 */
103 int
104 et_deregister(struct eventtimer *et)
105 {
106 int err = 0;
107
108 if (et->et_deregister_cb != NULL) {
109 if ((err = et->et_deregister_cb(et, et->et_arg)) != 0)
110 return (err);
111 }
112
113 ET_LOCK();
114 SLIST_REMOVE(&eventtimers, et, eventtimer, et_all);
115 ET_UNLOCK();
116 sysctl_remove_oid(et->et_sysctl, 1, 1);
117 return (0);
118 }
119
120 /*
121 * Change the frequency of the given timer. If it is the active timer,
122 * reconfigure it on all CPUs (reschedules all current events based on the new
123 * timer frequency).
124 */
125 void
126 et_change_frequency(struct eventtimer *et, uint64_t newfreq)
127 {
128
129 #ifndef NO_EVENTTIMERS
130 cpu_et_frequency(et, newfreq);
131 #endif
132 }
133
134 /*
135 * Find free event timer hardware with specified parameters.
136 */
137 struct eventtimer *
138 et_find(const char *name, int check, int want)
139 {
140 struct eventtimer *et = NULL;
141
142 SLIST_FOREACH(et, &eventtimers, et_all) {
143 if (et->et_active)
144 continue;
145 if (name != NULL && strcasecmp(et->et_name, name) != 0)
146 continue;
147 if (name == NULL && et->et_quality < 0)
148 continue;
149 if ((et->et_flags & check) != want)
150 continue;
151 break;
152 }
153 return (et);
154 }
155
156 /*
157 * Initialize event timer hardware. Set callbacks.
158 */
159 int
160 et_init(struct eventtimer *et, et_event_cb_t *event,
161 et_deregister_cb_t *deregister, void *arg)
162 {
163
164 if (event == NULL)
165 return (EINVAL);
166 if (et->et_active)
167 return (EBUSY);
168
169 et->et_active = 1;
170 et->et_event_cb = event;
171 et->et_deregister_cb = deregister;
172 et->et_arg = arg;
173 return (0);
174 }
175
176 /*
177 * Start event timer hardware.
178 * first - delay before first tick.
179 * period - period of subsequent periodic ticks.
180 */
181 int
182 et_start(struct eventtimer *et, sbintime_t first, sbintime_t period)
183 {
184
185 if (!et->et_active)
186 return (ENXIO);
187 KASSERT(period >= 0, ("et_start: negative period"));
188 KASSERT((et->et_flags & ET_FLAGS_PERIODIC) || period == 0,
189 ("et_start: period specified for oneshot-only timer"));
190 KASSERT((et->et_flags & ET_FLAGS_ONESHOT) || period != 0,
191 ("et_start: period not specified for periodic-only timer"));
192 if (period != 0) {
193 if (period < et->et_min_period)
194 period = et->et_min_period;
195 else if (period > et->et_max_period)
196 period = et->et_max_period;
197 }
198 if (period == 0 || first != 0) {
199 if (first < et->et_min_period)
200 first = et->et_min_period;
201 else if (first > et->et_max_period)
202 first = et->et_max_period;
203 }
204 return (et->et_start(et, first, period));
205 }
206
207 /* Stop event timer hardware. */
208 int
209 et_stop(struct eventtimer *et)
210 {
211
212 if (!et->et_active)
213 return (ENXIO);
214 if (et->et_stop)
215 return (et->et_stop(et));
216 return (0);
217 }
218
219 /* Mark event timer hardware as broken. */
220 int
221 et_ban(struct eventtimer *et)
222 {
223
224 et->et_flags &= ~(ET_FLAGS_PERIODIC | ET_FLAGS_ONESHOT);
225 return (0);
226 }
227
228 /* Free event timer hardware. */
229 int
230 et_free(struct eventtimer *et)
231 {
232
233 if (!et->et_active)
234 return (ENXIO);
235
236 et->et_active = 0;
237 return (0);
238 }
239
240 /* Report list of supported event timer hardware via sysctl. */
241 static int
242 sysctl_kern_eventtimer_choice(SYSCTL_HANDLER_ARGS)
243 {
244 struct sbuf sb;
245 struct eventtimer *et;
246 int error;
247
248 sbuf_new(&sb, NULL, 256, SBUF_AUTOEXTEND | SBUF_INCLUDENUL);
249
250 ET_LOCK();
251 SLIST_FOREACH(et, &eventtimers, et_all) {
252 if (et != SLIST_FIRST(&eventtimers))
253 sbuf_putc(&sb, ' ');
254 sbuf_printf(&sb, "%s(%d)", et->et_name, et->et_quality);
255 }
256 ET_UNLOCK();
257
258 error = sbuf_finish(&sb);
259 if (error == 0)
260 error = SYSCTL_OUT(req, sbuf_data(&sb), sbuf_len(&sb));
261 sbuf_delete(&sb);
262 return (error);
263 }
264 SYSCTL_PROC(_kern_eventtimer, OID_AUTO, choice,
265 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
266 0, 0, sysctl_kern_eventtimer_choice, "A", "Present event timers");
267
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