1 /* $NetBSD: mips3_clock.c,v 1.15 2020/05/29 12:30:40 rin 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> /* RCS ID & Copyright macro defns */
42
43 #include "opt_multiprocessor.h"
44
45 __KERNEL_RCSID(0, "$NetBSD: mips3_clock.c,v 1.15 2020/05/29 12:30:40 rin Exp $");
46
47 #include <sys/param.h>
48 #include <sys/cpu.h>
49 #include <sys/intr.h>
50 #include <sys/kernel.h>
51 #include <sys/timetc.h>
52
53 #include <mips/mips3_clock.h>
54
55 #include <mips/locore.h>
56
57 /*
58 * Wait for at least "n" microseconds.
59 */
60 void
mips3_delay(int n)61 mips3_delay(int n)
62 {
63 u_long divisor_delay;
64 uint32_t cur, last, delta, usecs;
65
66 last = mips3_cp0_count_read();
67 delta = usecs = 0;
68
69 divisor_delay = curcpu()->ci_divisor_delay;
70 if (divisor_delay == 0) {
71 /*
72 * Frequency values in curcpu() are not initialized.
73 * Assume faster frequency since longer delays are harmless.
74 * Note CPU_MIPS_DOUBLE_COUNT is ignored here.
75 */
76 #define FAST_FREQ (300 * 1000 * 1000) /* fast enough? */
77 divisor_delay = FAST_FREQ / (1000 * 1000);
78 }
79
80 while (n > usecs) {
81 cur = mips3_cp0_count_read();
82
83 /*
84 * The MIPS3 CP0 counter always counts upto UINT32_MAX,
85 * so no need to check wrapped around case.
86 */
87 delta += (cur - last);
88
89 last = cur;
90
91 while (delta >= divisor_delay) {
92 /*
93 * delta is not so larger than divisor_delay here,
94 * and using DIV/DIVU ops could be much slower.
95 * (though longer delay may be harmless)
96 */
97 usecs++;
98 delta -= divisor_delay;
99 }
100 }
101 }
102
103 /*
104 * Support for using the MIPS 3 clock as a timecounter.
105 */
106
107 void
mips3_init_tc(void)108 mips3_init_tc(void)
109 {
110 #if !defined(MULTIPROCESSOR)
111 static struct timecounter tc = {
112 .tc_get_timecount = (timecounter_get_t *)mips3_cp0_count_read,
113 .tc_counter_mask = ~0u,
114 .tc_name = "mips3_cp0_counter",
115 .tc_quality = 100,
116 };
117
118 tc.tc_frequency = curcpu()->ci_cpu_freq;
119 if (mips_options.mips_cpu_flags & CPU_MIPS_DOUBLE_COUNT) {
120 tc.tc_frequency /= 2;
121 }
122 curcpu()->ci_cctr_freq = tc.tc_frequency;
123
124 tc_init(&tc);
125 #endif
126 }
127
128 __weak_alias(delay, mips3_delay);
129