1 /* $OpenBSD: powernow.c,v 1.6 2014/09/14 14:17:23 jsg Exp $ */
2 /*
3 * Copyright (c) 2004 Ted Unangst
4 * All rights reserved.
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 /*
20 * AMD K6 PowerNow driver, see AMD tech doc #23525
21 * Numerous hints from Linux cpufreq driver
22 */
23
24 #include <sys/param.h>
25 #include <sys/systm.h>
26 #include <sys/sysctl.h>
27
28 #include <machine/cpu.h>
29 #include <machine/cpufunc.h>
30 #include <machine/specialreg.h>
31 #include <machine/pio.h>
32
33 /* table 27 in amd 23535. entries after 45 taken from linux cpufreq */
34 struct {
35 int mult; /* not actually used, maybe for cpuspeed */
36 int magic;
37 } k6_multipliers[] = {
38 { 20, 4 },
39 { 30, 5 },
40 { 35, 7 },
41 { 40, 2 },
42 { 45, 0 },
43 { 55, 3 },
44 { 50, 1 },
45 { 60, 6 },
46 };
47 #define NUM_K6_ENTRIES (sizeof k6_multipliers / sizeof k6_multipliers[0])
48
49 int k6_maxindex; /* no setting higher than this */
50
51 /* linux says: "it doesn't matter where, as long as it is unused */
52 #define K6PORT 0xfff0
53
54 void
k6_powernow_init(void)55 k6_powernow_init(void)
56 {
57 uint64_t msrval;
58 uint32_t portval;
59 int i;
60
61 /* on */
62 msrval = K6PORT | 0x1;
63 wrmsr(MSR_K6_EPMR, msrval);
64 /* read */
65 portval = inl(K6PORT + 8);
66 /* off */
67 wrmsr(MSR_K6_EPMR, 0LL);
68
69 portval = (portval >> 5) & 7;
70
71 for (i = 0; i < NUM_K6_ENTRIES; i++)
72 if (portval == k6_multipliers[i].magic) {
73 k6_maxindex = i;
74 break;
75 }
76 if (i == NUM_K6_ENTRIES) {
77 printf("bad value for current multiplier\n");
78 return;
79 }
80
81 cpu_setperf = k6_powernow_setperf;
82 }
83
84 void
k6_powernow_setperf(int level)85 k6_powernow_setperf(int level)
86 {
87 uint64_t msrval;
88 uint32_t portval;
89 int index;
90
91 index = level * k6_maxindex / 100;
92
93 /* on */
94 msrval = K6PORT | 0x1;
95 wrmsr(MSR_K6_EPMR, msrval);
96 /* read and update */
97 portval = inl(K6PORT + 8);
98 portval &= 0xf;
99 portval |= 1 << 12 | 1 << 10 | 1 << 9 |
100 k6_multipliers[index].magic << 5;
101 outl(K6PORT + 8, portval);
102 /* off */
103 wrmsr(MSR_K6_EPMR, 0LL);
104 }
105