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bf6fc9fd DJ |
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> | |
6072ace4 DJ |
22 | #include <linux/timex.h> |
23 | #include <linux/io.h> | |
bf6fc9fd | 24 | |
fa8031ae | 25 | #include <asm/cpu_device_id.h> |
bf6fc9fd | 26 | #include <asm/msr.h> |
bf6fc9fd DJ |
27 | |
28 | #define MMCR_BASE 0xfffef000 /* The default base address */ | |
29 | #define OFFS_CPUCTL 0x2 /* CPU Control Register */ | |
30 | ||
31 | static __u8 __iomem *cpuctl; | |
32 | ||
6072ace4 | 33 | #define PFX "sc520_freq: " |
bf6fc9fd DJ |
34 | |
35 | static struct cpufreq_frequency_table sc520_freq_table[] = { | |
36 | {0x01, 100000}, | |
37 | {0x02, 133000}, | |
38 | {0, CPUFREQ_TABLE_END}, | |
39 | }; | |
40 | ||
41 | static unsigned int sc520_freq_get_cpu_frequency(unsigned int cpu) | |
42 | { | |
43 | u8 clockspeed_reg = *cpuctl; | |
44 | ||
45 | switch (clockspeed_reg & 0x03) { | |
46 | default: | |
6072ace4 DJ |
47 | printk(KERN_ERR PFX "error: cpuctl register has unexpected " |
48 | "value %02x\n", clockspeed_reg); | |
bf6fc9fd DJ |
49 | case 0x01: |
50 | return 100000; | |
51 | case 0x02: | |
52 | return 133000; | |
53 | } | |
54 | } | |
55 | ||
6072ace4 | 56 | static void sc520_freq_set_cpu_state(unsigned int state) |
bf6fc9fd DJ |
57 | { |
58 | ||
59 | struct cpufreq_freqs freqs; | |
60 | u8 clockspeed_reg; | |
61 | ||
62 | freqs.old = sc520_freq_get_cpu_frequency(0); | |
63 | freqs.new = sc520_freq_table[state].frequency; | |
64 | freqs.cpu = 0; /* AMD Elan is UP */ | |
65 | ||
66 | cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); | |
67 | ||
2d06d8c4 | 68 | pr_debug("attempting to set frequency to %i kHz\n", |
bf6fc9fd DJ |
69 | 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 | ||
78 | cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); | |
79 | }; | |
80 | ||
6072ace4 | 81 | static int sc520_freq_verify(struct cpufreq_policy *policy) |
bf6fc9fd DJ |
82 | { |
83 | return cpufreq_frequency_table_verify(policy, &sc520_freq_table[0]); | |
84 | } | |
85 | ||
6072ace4 | 86 | static int sc520_freq_target(struct cpufreq_policy *policy, |
bf6fc9fd DJ |
87 | unsigned int target_freq, |
88 | unsigned int relation) | |
89 | { | |
90 | unsigned int newstate = 0; | |
91 | ||
6072ace4 DJ |
92 | if (cpufreq_frequency_table_target(policy, sc520_freq_table, |
93 | target_freq, relation, &newstate)) | |
bf6fc9fd DJ |
94 | return -EINVAL; |
95 | ||
96 | sc520_freq_set_cpu_state(newstate); | |
97 | ||
98 | return 0; | |
99 | } | |
100 | ||
101 | ||
102 | /* | |
103 | * Module init and exit code | |
104 | */ | |
105 | ||
106 | static int sc520_freq_cpu_init(struct cpufreq_policy *policy) | |
107 | { | |
92cb7612 | 108 | struct cpuinfo_x86 *c = &cpu_data(0); |
bf6fc9fd DJ |
109 | 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 */ | |
bf6fc9fd DJ |
117 | 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) | |
6072ace4 | 122 | return result; |
bf6fc9fd DJ |
123 | |
124 | cpufreq_frequency_table_get_attr(sc520_freq_table, policy->cpu); | |
125 | ||
126 | return 0; | |
127 | } | |
128 | ||
129 | ||
130 | static int sc520_freq_cpu_exit(struct cpufreq_policy *policy) | |
131 | { | |
132 | cpufreq_frequency_table_put_attr(policy->cpu); | |
133 | return 0; | |
134 | } | |
135 | ||
136 | ||
6072ace4 | 137 | static struct freq_attr *sc520_freq_attr[] = { |
bf6fc9fd DJ |
138 | &cpufreq_freq_attr_scaling_available_freqs, |
139 | NULL, | |
140 | }; | |
141 | ||
142 | ||
221dee28 | 143 | static struct cpufreq_driver sc520_freq_driver = { |
bf6fc9fd DJ |
144 | .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 | ||
fa8031ae AK |
154 | static const struct x86_cpu_id sc520_ids[] = { |
155 | { X86_VENDOR_AMD, 4, 9 }, | |
156 | {} | |
157 | }; | |
158 | MODULE_DEVICE_TABLE(x86cpu, sc520_ids); | |
bf6fc9fd DJ |
159 | |
160 | static int __init sc520_freq_init(void) | |
161 | { | |
3e74341c | 162 | int err; |
bf6fc9fd | 163 | |
fa8031ae | 164 | if (!x86_match_cpu(sc520_ids)) |
bf6fc9fd | 165 | return -ENODEV; |
fa8031ae | 166 | |
bf6fc9fd | 167 | cpuctl = ioremap((unsigned long)(MMCR_BASE + OFFS_CPUCTL), 1); |
6072ace4 | 168 | if (!cpuctl) { |
bf6fc9fd DJ |
169 | printk(KERN_ERR "sc520_freq: error: failed to remap memory\n"); |
170 | return -ENOMEM; | |
171 | } | |
172 | ||
3e74341c AL |
173 | err = cpufreq_register_driver(&sc520_freq_driver); |
174 | if (err) | |
175 | iounmap(cpuctl); | |
176 | ||
177 | return err; | |
bf6fc9fd DJ |
178 | } |
179 | ||
180 | ||
181 | static void __exit sc520_freq_exit(void) | |
182 | { | |
183 | cpufreq_unregister_driver(&sc520_freq_driver); | |
184 | iounmap(cpuctl); | |
185 | } | |
186 | ||
187 | ||
188 | MODULE_LICENSE("GPL"); | |
189 | MODULE_AUTHOR("Sean Young <sean@mess.org>"); | |
190 | MODULE_DESCRIPTION("cpufreq driver for AMD's Elan sc520 CPU"); | |
191 | ||
192 | module_init(sc520_freq_init); | |
193 | module_exit(sc520_freq_exit); | |
194 |