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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * sc520_freq.c: cpufreq driver for the AMD Elan sc520
4 *
5 * Copyright (C) 2005 Sean Young <sean@mess.org>
6 *
7 * Based on elanfreq.c
8 *
9 * 2005-03-30: - initial revision
10 */
11
12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/init.h>
17
18#include <linux/delay.h>
19#include <linux/cpufreq.h>
20#include <linux/timex.h>
21#include <linux/io.h>
22
23#include <asm/cpu_device_id.h>
24#include <asm/msr.h>
25
26#define MMCR_BASE 0xfffef000 /* The default base address */
27#define OFFS_CPUCTL 0x2 /* CPU Control Register */
28
29static __u8 __iomem *cpuctl;
30
31static struct cpufreq_frequency_table sc520_freq_table[] = {
32 {0, 0x01, 100000},
33 {0, 0x02, 133000},
34 {0, 0, CPUFREQ_TABLE_END},
35};
36
37static unsigned int sc520_freq_get_cpu_frequency(unsigned int cpu)
38{
39 u8 clockspeed_reg = *cpuctl;
40
41 switch (clockspeed_reg & 0x03) {
42 default:
43 pr_err("error: cpuctl register has unexpected value %02x\n",
44 clockspeed_reg);
45 fallthrough;
46 case 0x01:
47 return 100000;
48 case 0x02:
49 return 133000;
50 }
51}
52
53static int sc520_freq_target(struct cpufreq_policy *policy, unsigned int state)
54{
55
56 u8 clockspeed_reg;
57
58 local_irq_disable();
59
60 clockspeed_reg = *cpuctl & ~0x03;
61 *cpuctl = clockspeed_reg | sc520_freq_table[state].driver_data;
62
63 local_irq_enable();
64
65 return 0;
66}
67
68/*
69 * Module init and exit code
70 */
71
72static int sc520_freq_cpu_init(struct cpufreq_policy *policy)
73{
74 struct cpuinfo_x86 *c = &cpu_data(0);
75
76 /* capability check */
77 if (c->x86_vendor != X86_VENDOR_AMD ||
78 c->x86 != 4 || c->x86_model != 9)
79 return -ENODEV;
80
81 /* cpuinfo and default policy values */
82 policy->cpuinfo.transition_latency = 1000000; /* 1ms */
83 policy->freq_table = sc520_freq_table;
84
85 return 0;
86}
87
88
89static struct cpufreq_driver sc520_freq_driver = {
90 .get = sc520_freq_get_cpu_frequency,
91 .verify = cpufreq_generic_frequency_table_verify,
92 .target_index = sc520_freq_target,
93 .init = sc520_freq_cpu_init,
94 .name = "sc520_freq",
95 .attr = cpufreq_generic_attr,
96};
97
98static const struct x86_cpu_id sc520_ids[] = {
99 X86_MATCH_VENDOR_FAM_MODEL(AMD, 4, 9, NULL),
100 {}
101};
102MODULE_DEVICE_TABLE(x86cpu, sc520_ids);
103
104static int __init sc520_freq_init(void)
105{
106 int err;
107
108 if (!x86_match_cpu(sc520_ids))
109 return -ENODEV;
110
111 cpuctl = ioremap((unsigned long)(MMCR_BASE + OFFS_CPUCTL), 1);
112 if (!cpuctl) {
113 pr_err("sc520_freq: error: failed to remap memory\n");
114 return -ENOMEM;
115 }
116
117 err = cpufreq_register_driver(&sc520_freq_driver);
118 if (err)
119 iounmap(cpuctl);
120
121 return err;
122}
123
124
125static void __exit sc520_freq_exit(void)
126{
127 cpufreq_unregister_driver(&sc520_freq_driver);
128 iounmap(cpuctl);
129}
130
131
132MODULE_LICENSE("GPL");
133MODULE_AUTHOR("Sean Young <sean@mess.org>");
134MODULE_DESCRIPTION("cpufreq driver for AMD's Elan sc520 CPU");
135
136module_init(sc520_freq_init);
137module_exit(sc520_freq_exit);
138
1/*
2 * sc520_freq.c: cpufreq driver for the AMD Elan sc520
3 *
4 * Copyright (C) 2005 Sean Young <sean@mess.org>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 *
11 * Based on elanfreq.c
12 *
13 * 2005-03-30: - initial revision
14 */
15
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/init.h>
19
20#include <linux/delay.h>
21#include <linux/cpufreq.h>
22#include <linux/timex.h>
23#include <linux/io.h>
24
25#include <asm/cpu_device_id.h>
26#include <asm/msr.h>
27
28#define MMCR_BASE 0xfffef000 /* The default base address */
29#define OFFS_CPUCTL 0x2 /* CPU Control Register */
30
31static __u8 __iomem *cpuctl;
32
33#define PFX "sc520_freq: "
34
35static struct cpufreq_frequency_table sc520_freq_table[] = {
36 {0, 0x01, 100000},
37 {0, 0x02, 133000},
38 {0, 0, CPUFREQ_TABLE_END},
39};
40
41static unsigned int sc520_freq_get_cpu_frequency(unsigned int cpu)
42{
43 u8 clockspeed_reg = *cpuctl;
44
45 switch (clockspeed_reg & 0x03) {
46 default:
47 printk(KERN_ERR PFX "error: cpuctl register has unexpected "
48 "value %02x\n", clockspeed_reg);
49 case 0x01:
50 return 100000;
51 case 0x02:
52 return 133000;
53 }
54}
55
56static int sc520_freq_target(struct cpufreq_policy *policy, unsigned int state)
57{
58
59 u8 clockspeed_reg;
60
61 local_irq_disable();
62
63 clockspeed_reg = *cpuctl & ~0x03;
64 *cpuctl = clockspeed_reg | sc520_freq_table[state].driver_data;
65
66 local_irq_enable();
67
68 return 0;
69}
70
71/*
72 * Module init and exit code
73 */
74
75static int sc520_freq_cpu_init(struct cpufreq_policy *policy)
76{
77 struct cpuinfo_x86 *c = &cpu_data(0);
78
79 /* capability check */
80 if (c->x86_vendor != X86_VENDOR_AMD ||
81 c->x86 != 4 || c->x86_model != 9)
82 return -ENODEV;
83
84 /* cpuinfo and default policy values */
85 policy->cpuinfo.transition_latency = 1000000; /* 1ms */
86
87 return cpufreq_table_validate_and_show(policy, sc520_freq_table);
88}
89
90
91static struct cpufreq_driver sc520_freq_driver = {
92 .get = sc520_freq_get_cpu_frequency,
93 .verify = cpufreq_generic_frequency_table_verify,
94 .target_index = sc520_freq_target,
95 .init = sc520_freq_cpu_init,
96 .name = "sc520_freq",
97 .attr = cpufreq_generic_attr,
98};
99
100static const struct x86_cpu_id sc520_ids[] = {
101 { X86_VENDOR_AMD, 4, 9 },
102 {}
103};
104MODULE_DEVICE_TABLE(x86cpu, sc520_ids);
105
106static int __init sc520_freq_init(void)
107{
108 int err;
109
110 if (!x86_match_cpu(sc520_ids))
111 return -ENODEV;
112
113 cpuctl = ioremap((unsigned long)(MMCR_BASE + OFFS_CPUCTL), 1);
114 if (!cpuctl) {
115 printk(KERN_ERR "sc520_freq: error: failed to remap memory\n");
116 return -ENOMEM;
117 }
118
119 err = cpufreq_register_driver(&sc520_freq_driver);
120 if (err)
121 iounmap(cpuctl);
122
123 return err;
124}
125
126
127static void __exit sc520_freq_exit(void)
128{
129 cpufreq_unregister_driver(&sc520_freq_driver);
130 iounmap(cpuctl);
131}
132
133
134MODULE_LICENSE("GPL");
135MODULE_AUTHOR("Sean Young <sean@mess.org>");
136MODULE_DESCRIPTION("cpufreq driver for AMD's Elan sc520 CPU");
137
138module_init(sc520_freq_init);
139module_exit(sc520_freq_exit);
140