xref: /netbsd-src/sys/external/bsd/drm2/linux/linux_hrtimer.c (revision 147f7663cf2cbe2cc5e5fbd2b3d4b5956344b310)
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