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      1 /* $NetBSD: clock.c,v 1.47 2022/04/05 04:33:36 skrll Exp $ */
      2 
      3 /*
      4  * Copyright (c) 1988 University of Utah.
      5  * Copyright (c) 1992, 1993
      6  *	The Regents of the University of California.  All rights reserved.
      7  *
      8  * This code is derived from software contributed to Berkeley by
      9  * the Systems Programming Group of the University of Utah Computer
     10  * Science Department and Ralph Campbell.
     11  *
     12  * Redistribution and use in source and binary forms, with or without
     13  * modification, are permitted provided that the following conditions
     14  * are met:
     15  * 1. Redistributions of source code must retain the above copyright
     16  *    notice, this list of conditions and the following disclaimer.
     17  * 2. Redistributions in binary form must reproduce the above copyright
     18  *    notice, this list of conditions and the following disclaimer in the
     19  *    documentation and/or other materials provided with the distribution.
     20  * 3. Neither the name of the University nor the names of its contributors
     21  *    may be used to endorse or promote products derived from this software
     22  *    without specific prior written permission.
     23  *
     24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     34  * SUCH DAMAGE.
     35  *
     36  * from: Utah Hdr: clock.c 1.18 91/01/21
     37  *
     38  *	@(#)clock.c	8.1 (Berkeley) 6/10/93
     39  */
     40 
     41 #include <sys/cdefs.h>
     42 __KERNEL_RCSID(0, "$NetBSD: clock.c,v 1.47 2022/04/05 04:33:36 skrll Exp $");
     43 
     44 #include <sys/param.h>
     45 #include <sys/kernel.h>
     46 #include <sys/systm.h>
     47 #include <sys/device.h>
     48 #include <sys/lwp.h>
     49 
     50 #include <machine/alpha.h>
     51 #include <machine/autoconf.h>
     52 #include <machine/cpuconf.h>
     53 #include <machine/cpu_counter.h>
     54 
     55 #include <alpha/alpha/clockvar.h>
     56 
     57 #define PCC_QUAL	1000
     58 
     59 void (*clock_init)(void *);
     60 void *clockdev;
     61 
     62 int	alpha_use_cctr;		/* != 0 if we're using the PCC timecounter */
     63 
     64 void
     65 clockattach(void (*fns)(void *), void *dev)
     66 {
     67 
     68 	/*
     69 	 * Just bookkeeping.  We only allow one system clock.  If
     70 	 * we're running on real hardware, enforce this.  If we're
     71 	 * running under Qemu, anything after the first one.
     72 	 */
     73 	if (clock_init != NULL) {
     74 		if (alpha_is_qemu) {
     75 			return;
     76 		}
     77 		panic("clockattach: multiple clocks");
     78 	}
     79 	clock_init = fns;
     80 	clockdev = dev;
     81 }
     82 
     83 /*
     84  * Start the real-time and statistics clocks. Leave stathz 0 since there
     85  * are no other timers available.
     86  */
     87 void
     88 cpu_initclocks(void)
     89 {
     90 
     91 	if (clock_init == NULL)
     92 		panic("cpu_initclocks: no clock attached");
     93 
     94 	/*
     95 	 * Establish the clock interrupt; it's a special case.
     96 	 *
     97 	 * We establish the clock interrupt this late because if
     98 	 * we do it at clock attach time, we may have never been at
     99 	 * spl0() since taking over the system.  Some versions of
    100 	 * PALcode save a clock interrupt, which would get delivered
    101 	 * when we spl0() in autoconf.c.  If established the clock
    102 	 * interrupt handler earlier, that interrupt would go to
    103 	 * hardclock, which would then fall over because p->p_stats
    104 	 * isn't set at that time.
    105 	 */
    106 	platform.clockintr = hardclock;
    107 	schedhz = 16;
    108 
    109 	/*
    110 	 * Initialize PCC timecounter, unless we're running in Qemu
    111 	 * (we will use a different timecounter in that case).
    112 	 */
    113 	if (!alpha_is_qemu) {
    114 		const uint64_t pcc_freq = cpu_frequency(curcpu());
    115 		cc_init(NULL, pcc_freq, "PCC", PCC_QUAL);
    116 		alpha_use_cctr = 1;
    117 	}
    118 
    119 	/*
    120 	 * Get the clock started.
    121 	 */
    122 	(*clock_init)(clockdev);
    123 }
    124 
    125 /*
    126  * Some platforms might have other per-cpu clock initialization.  This
    127  * is handled here.
    128  */
    129 void
    130 cpu_initclocks_secondary(void)
    131 {
    132 	(*clock_init)(clockdev);
    133 }
    134 
    135 /*
    136  * We assume newhz is either stathz or profhz, and that neither will
    137  * change after being set up above.  Could recalculate intervals here
    138  * but that would be a drag.
    139  */
    140 void
    141 setstatclockrate(int newhz)
    142 {
    143 
    144 	/* nothing we can do */
    145 }
    146