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      1 /*      $NetBSD: clock.c,v 1.27 2012/10/27 17:18:04 chs Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1992, 1993
      5  *      The Regents of the University of California.  All rights reserved.
      6  *
      7  * This software was developed by the Computer Systems Engineering group
      8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
      9  * contributed to Berkeley.
     10  *
     11  * All advertising materials mentioning features or use of this software
     12  * must display the following acknowledgement:
     13  *      This product includes software developed by the University of
     14  *      California, Lawrence Berkeley Laboratory.
     15  *
     16  * Redistribution and use in source and binary forms, with or without
     17  * modification, are permitted provided that the following conditions
     18  * are met:
     19  * 1. Redistributions of source code must retain the above copyright
     20  *    notice, this list of conditions and the following disclaimer.
     21  * 2. Redistributions in binary form must reproduce the above copyright
     22  *    notice, this list of conditions and the following disclaimer in the
     23  *    documentation and/or other materials provided with the distribution.
     24  * 3. Neither the name of the University nor the names of its contributors
     25  *    may be used to endorse or promote products derived from this software
     26  *    without specific prior written permission.
     27  *
     28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     38  * SUCH DAMAGE.
     39  *
     40  *      @(#)clock.c     8.1 (Berkeley) 6/11/93
     41  */
     42 
     43 #include <sys/cdefs.h>
     44 __KERNEL_RCSID(0, "$NetBSD: clock.c,v 1.27 2012/10/27 17:18:04 chs Exp $");
     45 
     46 #include <sys/param.h>
     47 #include <sys/kernel.h>
     48 #include <sys/systm.h>
     49 #include <sys/device.h>
     50 
     51 #include <machine/psl.h>
     52 #include <machine/bus.h>
     53 
     54 #include <dev/mvme/clockvar.h>
     55 
     56 static	struct clock_attach_args *clock_args;
     57 
     58 struct	evcnt clock_profcnt;
     59 struct	evcnt clock_statcnt;
     60 
     61 /*
     62  * Statistics clock interval and variance, in usec.  Variance must be a
     63  * power of two.  Since this gives us an even number, not an odd number,
     64  * we discard one case and compensate.  That is, a variance of 1024 would
     65  * give us offsets in [0..1023].  Instead, we take offsets in [1..1023].
     66  * This is symmetric about the point 512, or statvar/2, and thus averages
     67  * to that value (assuming uniform random numbers).
     68  */
     69 /* XXX fix comment to match value */
     70 int	clock_statvar = 8192;
     71 int	clock_statmin;		/* statclock interval - (1/2 * variance) */
     72 
     73 
     74 /*
     75  * Common parts of clock autoconfiguration.
     76  */
     77 void
     78 clock_config(device_t dev, struct clock_attach_args *ca, struct evcnt *ev)
     79 {
     80 	extern int delay_divisor;	/* from machdep.c */
     81 
     82 	/* Hook up that which we need. */
     83 	clock_args = ca;
     84 
     85 	evcnt_attach_dynamic(&clock_profcnt, EVCNT_TYPE_INTR, ev,
     86 	    device_xname(dev), "profint");
     87 	evcnt_attach_dynamic(&clock_statcnt, EVCNT_TYPE_INTR, ev,
     88 	    device_xname(dev), "statint");
     89 
     90 	/* Print info about the clock. */
     91 	printf(": delay_divisor %d\n", delay_divisor);
     92 }
     93 
     94 /*
     95  * Set up the real-time and statistics clocks.  Leave stathz 0 only
     96  * if no alternative timer is available.
     97  *
     98  * The frequencies of these clocks must be an even number of microseconds.
     99  */
    100 void
    101 cpu_initclocks(void)
    102 {
    103 	int statint, minint;
    104 
    105 	if (clock_args == NULL)
    106 		panic("clock not configured");
    107 
    108 	if (1000000 % hz) {
    109 		printf("cannot get %d Hz clock; using 100 Hz\n", hz);
    110 		hz = 100;
    111 		tick = 1000000 / hz;
    112 	}
    113 	if (stathz == 0)
    114 		stathz = hz;
    115 	if (1000000 % stathz) {
    116 		printf("cannot get %d Hz statclock; using 100 Hz\n", stathz);
    117 		stathz = 100;
    118 	}
    119 	profhz = stathz;	/* always */
    120 
    121 	statint = 1000000 / stathz;
    122 	minint = statint / 2 + 100;
    123 	while (clock_statvar > minint)
    124 		clock_statvar >>= 1;
    125 
    126 	clock_statmin = statint - (clock_statvar >> 1);
    127 
    128 	/* Call the machine-specific initclocks hook. */
    129 	(*clock_args->ca_initfunc)(clock_args->ca_arg, tick, statint);
    130 }
    131 
    132 void
    133 setstatclockrate(int newhz)
    134 {
    135 
    136 	/* XXX should we do something here? XXX */
    137 }
    138