1 /* $NetBSD: linux_hrtimer.c,v 1.3 2021/12/19 11:55:47 riastradh Exp $ */
2
3 /*-
4 * Copyright (c) 2021 The NetBSD Foundation, Inc.
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 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __KERNEL_RCSID(0, "$NetBSD: linux_hrtimer.c,v 1.3 2021/12/19 11:55:47 riastradh Exp $");
31
32 #include <sys/types.h>
33 #include <sys/callout.h>
34
35 #include <linux/hrtimer.h>
36 #include <linux/ktime.h>
37
38 static void hrtimer_fire(void *);
39
40 void
hrtimer_init(struct hrtimer * hrt,clockid_t clkid,enum hrtimer_mode mode)41 hrtimer_init(struct hrtimer *hrt, clockid_t clkid, enum hrtimer_mode mode)
42 {
43
44 KASSERTMSG(clkid == CLOCK_MONOTONIC, "clkid %d", clkid);
45
46 callout_init(&hrt->hrt_ch, CALLOUT_MPSAFE);
47 callout_setfunc(&hrt->hrt_ch, hrtimer_fire, hrt);
48 hrt->hrt_mode = mode;
49 }
50
51 static void
_hrtimer_schedule(struct hrtimer * hrt)52 _hrtimer_schedule(struct hrtimer *hrt)
53 {
54 int delta;
55
56 switch (hrt->hrt_mode) {
57 case HRTIMER_MODE_ABS:
58 panic("absolute hrtimer NYI");
59 break;
60 case HRTIMER_MODE_REL:
61 delta = ktime_to_ms(hrt->hrt_expires);
62 break;
63 default:
64 panic("invalid hrtimer mode %d", hrt->hrt_mode);
65 }
66 callout_schedule(&hrt->hrt_ch, delta);
67 }
68
69 static void
hrtimer_fire(void * cookie)70 hrtimer_fire(void *cookie)
71 {
72 struct hrtimer *hrt = cookie;
73
74 switch ((*hrt->function)(hrt)) {
75 case HRTIMER_RESTART:
76 _hrtimer_schedule(hrt);
77 break;
78 case HRTIMER_NORESTART:
79 break;
80 }
81
82 callout_ack(&hrt->hrt_ch);
83 }
84
85 void
hrtimer_set_expires(struct hrtimer * hrt,ktime_t expires)86 hrtimer_set_expires(struct hrtimer *hrt, ktime_t expires)
87 {
88
89 hrt->hrt_expires = expires;
90 }
91
92 void
hrtimer_add_expires_ns(struct hrtimer * hrt,uint64_t ns)93 hrtimer_add_expires_ns(struct hrtimer *hrt, uint64_t ns)
94 {
95
96 hrt->hrt_expires = ktime_add_ns(hrt->hrt_expires, ns);
97 }
98
99 void
hrtimer_start(struct hrtimer * hrt,ktime_t expires,enum hrtimer_mode mode)100 hrtimer_start(struct hrtimer *hrt, ktime_t expires, enum hrtimer_mode mode)
101 {
102
103 hrtimer_start_range_ns(hrt, expires, 0, mode);
104 }
105
106 void
hrtimer_start_range_ns(struct hrtimer * hrt,ktime_t expires,uint64_t range_ns,enum hrtimer_mode mode)107 hrtimer_start_range_ns(struct hrtimer *hrt, ktime_t expires, uint64_t range_ns,
108 enum hrtimer_mode mode)
109 {
110
111 hrt->hrt_expires = expires;
112 (void)range_ns;
113 hrt->hrt_mode = mode;
114 _hrtimer_schedule(hrt);
115 }
116
117 int
hrtimer_cancel(struct hrtimer * hrt)118 hrtimer_cancel(struct hrtimer *hrt)
119 {
120 bool active;
121
122 /*
123 * Halt the callout and ascertain whether the hrtimer was
124 * active when we invoked hrtimer_cancel.
125 */
126 if (callout_halt(&hrt->hrt_ch, NULL)) {
127 /* Callout expired, meaning it was active. */
128 active = true;
129 } else {
130 /*
131 * Callout had not yet expired. It will not expire
132 * now, so callout_pending is now stable and
133 * corresponds with whether the hrtimer was active or
134 * not.
135 */
136 active = callout_pending(&hrt->hrt_ch);
137 }
138 return active;
139 }
140
141 bool
hrtimer_active(struct hrtimer * hrt)142 hrtimer_active(struct hrtimer *hrt)
143 {
144
145 /*
146 * If the callout has been scheduled, but has not yet fired,
147 * then it is pending.
148 *
149 * If the callout has fired, but has not yet reached
150 * callout_ack, then it is invoking.
151 */
152 return callout_pending(&hrt->hrt_ch) || callout_invoking(&hrt->hrt_ch);
153 }
154
155 uint64_t
hrtimer_forward(struct hrtimer * hrt,ktime_t now,ktime_t period)156 hrtimer_forward(struct hrtimer *hrt, ktime_t now, ktime_t period)
157 {
158 uint64_t now_ms, period_ms, expires_ms, nperiods;
159
160 KASSERT(!callout_pending(&hrt->hrt_ch));
161
162 /*
163 * Can't get better than 10ms precision (or ~1ms if you set
164 * HZ=1000) so not much point in doing this arithmetic at finer
165 * resolution than ms.
166 */
167 now_ms = ktime_to_ms(now);
168 period_ms = ktime_to_ms(period);
169 expires_ms = ktime_to_ms(hrt->hrt_expires);
170
171 /* If it hasn't yet expired, no overruns. */
172 if (now_ms < expires_ms)
173 return 0;
174
175 /* Advance it by as many periods as it should have fired. */
176 /* XXX fenceposts */
177 nperiods = howmany(now_ms - expires_ms, period_ms);
178 hrt->hrt_expires = ktime_add_ns(hrt->hrt_expires,
179 1000000*nperiods*period_ms);
180
181 return nperiods;
182 }
183
184 uint64_t
hrtimer_forward_now(struct hrtimer * hrt,ktime_t period)185 hrtimer_forward_now(struct hrtimer *hrt, ktime_t period)
186 {
187
188 return hrtimer_forward(hrt, ktime_get(), period);
189 }
190