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Dave Jonesbf6fc9f2005-05-31 19:03:45 -07001/*
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>
Dave Jones6072ace2009-01-18 01:27:35 -050022#include <linux/timex.h>
23#include <linux/io.h>
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070024
Andi Kleenfa8031a2012-01-26 00:09:12 +010025#include <asm/cpu_device_id.h>
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070026#include <asm/msr.h>
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070027
28#define MMCR_BASE 0xfffef000 /* The default base address */
29#define OFFS_CPUCTL 0x2 /* CPU Control Register */
30
31static __u8 __iomem *cpuctl;
32
Dave Jones6072ace2009-01-18 01:27:35 -050033#define PFX "sc520_freq: "
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070034
35static struct cpufreq_frequency_table sc520_freq_table[] = {
36 {0x01, 100000},
37 {0x02, 133000},
38 {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:
Dave Jones6072ace2009-01-18 01:27:35 -050047 printk(KERN_ERR PFX "error: cpuctl register has unexpected "
48 "value %02x\n", clockspeed_reg);
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070049 case 0x01:
50 return 100000;
51 case 0x02:
52 return 133000;
53 }
54}
55
Viresh Kumarb43a7ff2013-03-24 11:56:43 +053056static void sc520_freq_set_cpu_state(struct cpufreq_policy *policy,
57 unsigned int state)
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070058{
59
60 struct cpufreq_freqs freqs;
61 u8 clockspeed_reg;
62
63 freqs.old = sc520_freq_get_cpu_frequency(0);
64 freqs.new = sc520_freq_table[state].frequency;
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070065
Viresh Kumarb43a7ff2013-03-24 11:56:43 +053066 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070067
Dominik Brodowski2d06d8c2011-03-27 15:04:46 +020068 pr_debug("attempting to set frequency to %i kHz\n",
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070069 sc520_freq_table[state].frequency);
70
71 local_irq_disable();
72
73 clockspeed_reg = *cpuctl & ~0x03;
74 *cpuctl = clockspeed_reg | sc520_freq_table[state].index;
75
76 local_irq_enable();
77
Viresh Kumarb43a7ff2013-03-24 11:56:43 +053078 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070079};
80
Dave Jones6072ace2009-01-18 01:27:35 -050081static int sc520_freq_verify(struct cpufreq_policy *policy)
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070082{
83 return cpufreq_frequency_table_verify(policy, &sc520_freq_table[0]);
84}
85
Dave Jones6072ace2009-01-18 01:27:35 -050086static int sc520_freq_target(struct cpufreq_policy *policy,
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070087 unsigned int target_freq,
88 unsigned int relation)
89{
90 unsigned int newstate = 0;
91
Dave Jones6072ace2009-01-18 01:27:35 -050092 if (cpufreq_frequency_table_target(policy, sc520_freq_table,
93 target_freq, relation, &newstate))
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070094 return -EINVAL;
95
Viresh Kumarb43a7ff2013-03-24 11:56:43 +053096 sc520_freq_set_cpu_state(policy, newstate);
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070097
98 return 0;
99}
100
101
102/*
103 * Module init and exit code
104 */
105
106static int sc520_freq_cpu_init(struct cpufreq_policy *policy)
107{
Mike Travis92cb7612007-10-19 20:35:04 +0200108 struct cpuinfo_x86 *c = &cpu_data(0);
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700109 int result;
110
111 /* capability check */
112 if (c->x86_vendor != X86_VENDOR_AMD ||
113 c->x86 != 4 || c->x86_model != 9)
114 return -ENODEV;
115
116 /* cpuinfo and default policy values */
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700117 policy->cpuinfo.transition_latency = 1000000; /* 1ms */
118 policy->cur = sc520_freq_get_cpu_frequency(0);
119
120 result = cpufreq_frequency_table_cpuinfo(policy, sc520_freq_table);
121 if (result)
Dave Jones6072ace2009-01-18 01:27:35 -0500122 return result;
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700123
124 cpufreq_frequency_table_get_attr(sc520_freq_table, policy->cpu);
125
126 return 0;
127}
128
129
130static int sc520_freq_cpu_exit(struct cpufreq_policy *policy)
131{
132 cpufreq_frequency_table_put_attr(policy->cpu);
133 return 0;
134}
135
136
Dave Jones6072ace2009-01-18 01:27:35 -0500137static struct freq_attr *sc520_freq_attr[] = {
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700138 &cpufreq_freq_attr_scaling_available_freqs,
139 NULL,
140};
141
142
Linus Torvalds221dee22007-02-26 14:55:48 -0800143static struct cpufreq_driver sc520_freq_driver = {
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700144 .get = sc520_freq_get_cpu_frequency,
145 .verify = sc520_freq_verify,
146 .target = sc520_freq_target,
147 .init = sc520_freq_cpu_init,
148 .exit = sc520_freq_cpu_exit,
149 .name = "sc520_freq",
150 .owner = THIS_MODULE,
151 .attr = sc520_freq_attr,
152};
153
Andi Kleenfa8031a2012-01-26 00:09:12 +0100154static const struct x86_cpu_id sc520_ids[] = {
155 { X86_VENDOR_AMD, 4, 9 },
156 {}
157};
158MODULE_DEVICE_TABLE(x86cpu, sc520_ids);
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700159
160static int __init sc520_freq_init(void)
161{
Amol Lad3e743412006-10-17 10:02:55 +0530162 int err;
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700163
Andi Kleenfa8031a2012-01-26 00:09:12 +0100164 if (!x86_match_cpu(sc520_ids))
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700165 return -ENODEV;
Andi Kleenfa8031a2012-01-26 00:09:12 +0100166
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700167 cpuctl = ioremap((unsigned long)(MMCR_BASE + OFFS_CPUCTL), 1);
Dave Jones6072ace2009-01-18 01:27:35 -0500168 if (!cpuctl) {
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700169 printk(KERN_ERR "sc520_freq: error: failed to remap memory\n");
170 return -ENOMEM;
171 }
172
Amol Lad3e743412006-10-17 10:02:55 +0530173 err = cpufreq_register_driver(&sc520_freq_driver);
174 if (err)
175 iounmap(cpuctl);
176
177 return err;
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700178}
179
180
181static void __exit sc520_freq_exit(void)
182{
183 cpufreq_unregister_driver(&sc520_freq_driver);
184 iounmap(cpuctl);
185}
186
187
188MODULE_LICENSE("GPL");
189MODULE_AUTHOR("Sean Young <sean@mess.org>");
190MODULE_DESCRIPTION("cpufreq driver for AMD's Elan sc520 CPU");
191
192module_init(sc520_freq_init);
193module_exit(sc520_freq_exit);
194