clock.c revision 1.28 
1/*	$OpenBSD: clock.c,v 1.28 2011/01/09 19:37:51 jasper Exp $	*/
2
3/*
4 * Copyright (c) 1998-2003 Michael Shalayeff
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 AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR OR HIS RELATIVES BE LIABLE FOR ANY DIRECT,
20 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
22 * SERVICES; LOSS OF MIND, USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
24 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
25 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
26 * THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <sys/param.h>
30#include <sys/systm.h>
31#include <sys/kernel.h>
32#include <sys/timetc.h>
33
34#include <dev/clock_subr.h>
35
36#include <machine/pdc.h>
37#include <machine/iomod.h>
38#include <machine/psl.h>
39#include <machine/intr.h>
40#include <machine/reg.h>
41#include <machine/cpufunc.h>
42#include <machine/autoconf.h>
43
44u_long	cpu_hzticks;
45int	timeset;
46
47int	cpu_hardclock(void *);
48u_int	itmr_get_timecount(struct timecounter *);
49
50struct timecounter itmr_timecounter = {
51	itmr_get_timecount, NULL, 0xffffffff, 0, "itmr", 0, NULL
52};
53
54void
55cpu_initclocks(void)
56{
57	struct cpu_info *ci = curcpu();
58	u_long __itmr;
59
60	cpu_hzticks = (PAGE0->mem_10msec * 100) / hz;
61
62	itmr_timecounter.tc_frequency = PAGE0->mem_10msec * 100;
63	tc_init(&itmr_timecounter);
64
65	mfctl(CR_ITMR, __itmr);
66	ci->ci_itmr = __itmr;
67	__itmr += cpu_hzticks;
68	mtctl(__itmr, CR_ITMR);
69}
70
71int
72cpu_hardclock(void *v)
73{
74	struct cpu_info *ci = curcpu();
75	u_long __itmr, delta, eta;
76	int wrap;
77	register_t eiem;
78
79	/*
80	 * Invoke hardclock as many times as there has been cpu_hzticks
81	 * ticks since the last interrupt.
82	 */
83	for (;;) {
84		mfctl(CR_ITMR, __itmr);
85		delta = __itmr - ci->ci_itmr;
86		if (delta >= cpu_hzticks) {
87			hardclock(v);
88			ci->ci_itmr += cpu_hzticks;
89		} else
90			break;
91	}
92
93	/*
94	 * Program the next clock interrupt, making sure it will
95	 * indeed happen in the future. This is done with interrupts
96	 * disabled to avoid a possible race.
97	 */
98	eta = ci->ci_itmr + cpu_hzticks;
99	wrap = eta < ci->ci_itmr;	/* watch out for a wraparound */
100	__asm __volatile("mfctl	%%cr15, %0": "=r" (eiem));
101	__asm __volatile("mtctl	%r0, %cr15");
102	mtctl(eta, CR_ITMR);
103	mfctl(CR_ITMR, __itmr);
104	/*
105	 * If we were close enough to the next tick interrupt
106	 * value, by the time we have programmed itmr, it might
107	 * have passed the value, which would cause a complete
108	 * cycle until the next interrupt occurs. On slow
109	 * models, this would be a disaster (a complete cycle
110	 * taking over two minutes on a 715/33).
111	 *
112	 * We expect that it will only be necessary to postpone
113	 * the interrupt once. Thus, there are two cases:
114	 * - We are expecting a wraparound: eta < cpu_itmr.
115	 *   itmr is in tracks if either >= cpu_itmr or < eta.
116	 * - We are not wrapping: eta > cpu_itmr.
117	 *   itmr is in tracks if >= cpu_itmr and < eta (we need
118	 *   to keep the >= cpu_itmr test because itmr might wrap
119	 *   before eta does).
120	 */
121	if ((wrap && !(eta > __itmr || __itmr >= ci->ci_itmr)) ||
122	    (!wrap && !(eta > __itmr && __itmr >= ci->ci_itmr))) {
123		eta += cpu_hzticks;
124		mtctl(eta, CR_ITMR);
125	}
126	__asm __volatile("mtctl	%0, %%cr15":: "r" (eiem));
127
128	return (1);
129}
130
131/*
132 * initialize the system time from the time of day clock
133 */
134void
135inittodr(time_t t)
136{
137	struct pdc_tod tod PDC_ALIGNMENT;
138	int 	error, tbad = 0;
139	struct timespec ts;
140
141	if (t < 12*SECYR) {
142		printf ("WARNING: preposterous time in file system");
143		t = 6*SECYR + 186*SECDAY + SECDAY/2;
144		tbad = 1;
145	}
146
147	if ((error = pdc_call((iodcio_t)pdc,
148	    1, PDC_TOD, PDC_TOD_READ, &tod, 0, 0, 0, 0, 0)))
149		printf("clock: failed to fetch (%d)\n", error);
150
151	ts.tv_sec = tod.sec;
152	ts.tv_nsec = tod.usec * 1000;
153	tc_setclock(&ts);
154	timeset = 1;
155
156	if (!tbad) {
157		u_long	dt;
158
159		dt = (tod.sec < t)?  t - tod.sec : tod.sec - t;
160
161		if (dt < 2 * SECDAY)
162			return;
163		printf("WARNING: clock %s %ld days",
164		    tod.sec < t? "lost" : "gained", dt / SECDAY);
165	}
166
167	printf (" -- CHECK AND RESET THE DATE!\n");
168}
169
170/*
171 * reset the time of day clock to the value in time
172 */
173void
174resettodr()
175{
176	struct timeval tv;
177	int error;
178
179	/*
180	 * We might have been called by boot() due to a crash early
181	 * on.  Don't reset the clock chip in this case.
182	 */
183	if (!timeset)
184		return;
185
186	microtime(&tv);
187
188	if ((error = pdc_call((iodcio_t)pdc, 1, PDC_TOD, PDC_TOD_WRITE,
189	    tv.tv_sec, tv.tv_usec)))
190		printf("clock: failed to save (%d)\n", error);
191}
192
193void
194setstatclockrate(int newhz)
195{
196	/* nothing we can do */
197}
198
199u_int
200itmr_get_timecount(struct timecounter *tc)
201{
202	u_long __itmr;
203
204	mfctl(CR_ITMR, __itmr);
205	return (__itmr);
206}
207