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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[] = {
Viresh Kumar7f4b0462014-03-28 19:11:47 +053036 {0, 0x01, 100000},
37 {0, 0x02, 133000},
38 {0, 0, CPUFREQ_TABLE_END},
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070039};
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 Kumar9c0ebcf2013-10-25 19:45:48 +053056static int sc520_freq_target(struct cpufreq_policy *policy, unsigned int state)
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070057{
58
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070059 u8 clockspeed_reg;
60
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070061 local_irq_disable();
62
63 clockspeed_reg = *cpuctl & ~0x03;
Viresh Kumar50701582013-03-30 16:25:15 +053064 *cpuctl = clockspeed_reg | sc520_freq_table[state].driver_data;
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070065
66 local_irq_enable();
67
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070068 return 0;
69}
70
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070071/*
72 * Module init and exit code
73 */
74
75static int sc520_freq_cpu_init(struct cpufreq_policy *policy)
76{
Mike Travis92cb7612007-10-19 20:35:04 +020077 struct cpuinfo_x86 *c = &cpu_data(0);
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070078
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 */
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070085 policy->cpuinfo.transition_latency = 1000000; /* 1ms */
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070086
Viresh Kumarae025192013-09-16 18:56:34 +053087 return cpufreq_table_validate_and_show(policy, sc520_freq_table);
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070088}
89
90
Linus Torvalds221dee22007-02-26 14:55:48 -080091static struct cpufreq_driver sc520_freq_driver = {
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070092 .get = sc520_freq_get_cpu_frequency,
Viresh Kumara823c4a2013-10-03 20:28:24 +053093 .verify = cpufreq_generic_frequency_table_verify,
Viresh Kumar9c0ebcf2013-10-25 19:45:48 +053094 .target_index = sc520_freq_target,
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070095 .init = sc520_freq_cpu_init,
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070096 .name = "sc520_freq",
Viresh Kumara823c4a2013-10-03 20:28:24 +053097 .attr = cpufreq_generic_attr,
Dave Jonesbf6fc9f2005-05-31 19:03:45 -070098};
99
Andi Kleenfa8031a2012-01-26 00:09:12 +0100100static const struct x86_cpu_id sc520_ids[] = {
101 { X86_VENDOR_AMD, 4, 9 },
102 {}
103};
104MODULE_DEVICE_TABLE(x86cpu, sc520_ids);
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700105
106static int __init sc520_freq_init(void)
107{
Amol Lad3e743412006-10-17 10:02:55 +0530108 int err;
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700109
Andi Kleenfa8031a2012-01-26 00:09:12 +0100110 if (!x86_match_cpu(sc520_ids))
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700111 return -ENODEV;
Andi Kleenfa8031a2012-01-26 00:09:12 +0100112
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700113 cpuctl = ioremap((unsigned long)(MMCR_BASE + OFFS_CPUCTL), 1);
Dave Jones6072ace2009-01-18 01:27:35 -0500114 if (!cpuctl) {
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700115 printk(KERN_ERR "sc520_freq: error: failed to remap memory\n");
116 return -ENOMEM;
117 }
118
Amol Lad3e743412006-10-17 10:02:55 +0530119 err = cpufreq_register_driver(&sc520_freq_driver);
120 if (err)
121 iounmap(cpuctl);
122
123 return err;
Dave Jonesbf6fc9f2005-05-31 19:03:45 -0700124}
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