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      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
     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
     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
     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
     86 hrtimer_set_expires(struct hrtimer *hrt, ktime_t expires)
     87 {
     88 
     89 	hrt->hrt_expires = expires;
     90 }
     91 
     92 void
     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
    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
    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
    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
    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
    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
    185 hrtimer_forward_now(struct hrtimer *hrt, ktime_t period)
    186 {
    187 
    188 	return hrtimer_forward(hrt, ktime_get(), period);
    189 }
    190