kern_cctr.c revision 1.5 
1/* $NetBSD: kern_cctr.c,v 1.5 2008/04/05 18:17:36 tsutsui Exp $ */
2
3
4/*-
5 * Copyright (c) 2006 The NetBSD Foundation, Inc.
6 * All rights reserved.
7 *
8 * re-implementation of TSC for MP systems merging cc_microtime and
9 * TSC for timecounters by Frank Kardel
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 3. All advertising materials mentioning features or use of this software
20 *    must display the following acknowledgement:
21 *	This product includes software developed by the NetBSD
22 *	Foundation, Inc. and its contributors.
23 * 4. Neither the name of The NetBSD Foundation nor the names of its
24 *    contributors may be used to endorse or promote products derived
25 *    from this software without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
28 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
29 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
30 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
31 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
32 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
33 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
34 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
35 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
36 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
37 * POSSIBILITY OF SUCH DAMAGE.
38 */
39
40/* basic calibration ideas are (kern_microtime.c): */
41/******************************************************************************
42 *                                                                            *
43 * Copyright (c) David L. Mills 1993, 1994                                    *
44 *                                                                            *
45 * Permission to use, copy, modify, and distribute this software and its      *
46 * documentation for any purpose and without fee is hereby granted, provided  *
47 * that the above copyright notice appears in all copies and that both the    *
48 * copyright notice and this permission notice appear in supporting           *
49 * documentation, and that the name University of Delaware not be used in     *
50 * advertising or publicity pertaining to distribution of the software        *
51 * without specific, written prior permission.  The University of Delaware    *
52 * makes no representations about the suitability this software for any       *
53 * purpose.  It is provided "as is" without express or implied warranty.      *
54 *                                                                            *
55 ******************************************************************************/
56
57/* reminiscents from older version of this file are: */
58/*-
59 * Copyright (c) 1998-2003 Poul-Henning Kamp
60 * All rights reserved.
61 *
62 * Redistribution and use in source and binary forms, with or without
63 * modification, are permitted provided that the following conditions
64 * are met:
65 * 1. Redistributions of source code must retain the above copyright
66 *    notice, this list of conditions and the following disclaimer.
67 * 2. Redistributions in binary form must reproduce the above copyright
68 *    notice, this list of conditions and the following disclaimer in the
69 *    documentation and/or other materials provided with the distribution.
70 *
71 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
72 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
73 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
74 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
75 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
76 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
77 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
78 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
79 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
80 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
81 * SUCH DAMAGE.
82 */
83
84#include <sys/cdefs.h>
85/* __FBSDID("$FreeBSD: src/sys/i386/i386/tsc.c,v 1.204 2003/10/21 18:28:34 silby Exp $"); */
86__KERNEL_RCSID(0, "$NetBSD: kern_cctr.c,v 1.5 2008/04/05 18:17:36 tsutsui Exp $");
87
88#include "opt_multiprocessor.h"
89
90#include <sys/param.h>
91#include <sys/systm.h>
92#include <sys/sysctl.h>
93#include <sys/time.h>
94#include <sys/timetc.h>
95#include <sys/kernel.h>
96#include <sys/power.h>
97#include <sys/cpu.h>
98#include <machine/cpu_counter.h>
99
100/* XXX make cc_timecounter.tc_frequency settable by sysctl() */
101
102static timecounter_pps_t cc_calibrate;
103
104void cc_calibrate_cpu(struct cpu_info *);
105
106static int64_t cc_cal_val;  /* last calibrate time stamp */
107
108static struct timecounter cc_timecounter = {
109	.tc_get_timecount	= cc_get_timecount,
110	.tc_poll_pps		= cc_calibrate,
111	.tc_counter_mask	= ~0u,
112	.tc_frequency		= 0,
113	.tc_name		= "unkown cycle counter",
114	/*
115	 * don't pick cycle counter automatically
116	 * if frequency changes might affect cycle counter
117	 */
118	.tc_quality		= -100000,
119
120	.tc_priv		= NULL,
121	.tc_next		= NULL
122};
123
124/*
125 * initialize cycle counter based timecounter
126 */
127struct timecounter *
128cc_init(timecounter_get_t getcc, uint64_t freq, const char *name, int quality)
129{
130
131	if (getcc != NULL)
132		cc_timecounter.tc_get_timecount = getcc;
133
134	cc_timecounter.tc_frequency = freq;
135	cc_timecounter.tc_name = name;
136	cc_timecounter.tc_quality = quality;
137	tc_init(&cc_timecounter);
138
139	return &cc_timecounter;
140}
141
142/*
143 * pick up tick count scaled to reference tick count
144 */
145u_int
146cc_get_timecount(struct timecounter *tc)
147{
148	struct cpu_info *ci = curcpu();
149	int64_t rcc, cc;
150	u_int gen;
151
152	if (ci->ci_cc.cc_denom == 0) {
153		/*
154		 * This is our first time here on this CPU.  Just
155		 * start with reasonable initial values.
156		 */
157	        ci->ci_cc.cc_cc    = cpu_counter32();
158		ci->ci_cc.cc_val   = 0;
159		if (ci->ci_cc.cc_gen == 0)
160			ci->ci_cc.cc_gen++;
161
162		ci->ci_cc.cc_denom = cpu_frequency(ci);
163		if (ci->ci_cc.cc_denom == 0)
164			ci->ci_cc.cc_denom = cc_timecounter.tc_frequency;
165		ci->ci_cc.cc_delta = ci->ci_cc.cc_denom;
166	}
167
168	/*
169	 * read counter and re-read when the re-calibration
170	 * strikes inbetween
171	 */
172	do {
173		/* pick up current generation number */
174		gen = ci->ci_cc.cc_gen;
175
176		/* determine local delta ticks */
177		cc = cpu_counter32() - ci->ci_cc.cc_cc;
178		if (cc < 0)
179			cc += 0x100000000LL;
180
181		/* scale to primary */
182		rcc = (cc * ci->ci_cc.cc_delta) / ci->ci_cc.cc_denom
183		    + ci->ci_cc.cc_val;
184	} while (gen == 0 || gen != ci->ci_cc.cc_gen);
185
186	return rcc;
187}
188
189/*
190 * called once per clock tick via the pps callback
191 * for the calibration of the TSC counters.
192 * it is called only for the PRIMARY cpu. all
193 * other cpus are called via a broadcast IPI
194 * calibration interval is 1 second - we call
195 * the calibration code only every hz calls
196 */
197static void
198cc_calibrate(struct timecounter *tc)
199{
200	static int calls;
201	struct cpu_info *ci;
202
203	 /*
204	  * XXX: for high interrupt frequency
205	  * support: ++calls < hz / tc_tick
206	  */
207	if (++calls < hz)
208		return;
209
210	calls = 0;
211	ci = curcpu();
212	/* pick up reference ticks */
213	cc_cal_val = cpu_counter32();
214
215#if defined(MULTIPROCESSOR)
216	cc_calibrate_mp(ci);
217#endif
218	cc_calibrate_cpu(ci);
219}
220
221/*
222 * This routine is called about once per second directly by the master
223 * processor and via an interprocessor interrupt for other processors.
224 * It determines the CC frequency of each processor relative to the
225 * master clock and the time this determination is made.  These values
226 * are used by cc_get_timecount() to interpolate the ticks between
227 * timer interrupts.  Note that we assume the kernel variables have
228 * been zeroed early in life.
229 */
230void
231cc_calibrate_cpu(struct cpu_info *ci)
232{
233	u_int   gen;
234	int64_t val;
235	int64_t delta, denom;
236	int s;
237#ifdef TIMECOUNTER_DEBUG
238	int64_t factor, old_factor;
239#endif
240	val = cc_cal_val;
241
242	s = splhigh();
243	/* create next generation number */
244	gen = ci->ci_cc.cc_gen;
245	gen++;
246	if (gen == 0)
247		gen++;
248
249	/* update in progress */
250	ci->ci_cc.cc_gen = 0;
251
252	denom = ci->ci_cc.cc_cc;
253	ci->ci_cc.cc_cc = cpu_counter32();
254
255	if (ci->ci_cc.cc_denom == 0) {
256		/*
257		 * This is our first time here on this CPU.  Just
258		 * start with reasonable initial values.
259		 */
260		ci->ci_cc.cc_val = val;
261		ci->ci_cc.cc_denom = cpu_frequency(ci);
262		if (ci->ci_cc.cc_denom == 0)
263			ci->ci_cc.cc_denom = cc_timecounter.tc_frequency;;
264		ci->ci_cc.cc_delta = ci->ci_cc.cc_denom;
265		ci->ci_cc.cc_gen = gen;
266		splx(s);
267		return;
268	}
269
270#ifdef TIMECOUNTER_DEBUG
271	old_factor = (ci->ci_cc.cc_delta * 1000 ) / ci->ci_cc.cc_denom;
272#endif
273
274	/* local ticks per period */
275	denom = ci->ci_cc.cc_cc - denom;
276	if (denom < 0)
277		denom += 0x100000000LL;
278
279	ci->ci_cc.cc_denom = denom;
280
281	/* reference ticks per period */
282	delta = val - ci->ci_cc.cc_val;
283	if (delta < 0)
284		delta += 0x100000000LL;
285
286	ci->ci_cc.cc_val = val;
287	ci->ci_cc.cc_delta = delta;
288
289	/* publish new generation number */
290	ci->ci_cc.cc_gen = gen;
291	splx(s);
292
293#ifdef TIMECOUNTER_DEBUG
294	factor = (delta * 1000) / denom - old_factor;
295	if (factor < 0)
296		factor = -factor;
297
298	if (factor > old_factor / 10)
299		printf("cc_calibrate_cpu[%u]: 10%% exceeded - delta %"
300		    PRId64 ", denom %" PRId64 ", factor %" PRId64
301		    ", old factor %" PRId64"\n", ci->ci_index,
302		    delta, denom, (delta * 1000) / denom, old_factor);
303#endif /* TIMECOUNTER_DEBUG */
304}
305