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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 DJ |
24 | |
25 | #include <asm/msr.h> | |
bf6fc9fd DJ |
26 | |
27 | #define MMCR_BASE 0xfffef000 /* The default base address */ | |
28 | #define OFFS_CPUCTL 0x2 /* CPU Control Register */ | |
29 | ||
30 | static __u8 __iomem *cpuctl; | |
31 | ||
6072ace4 | 32 | #define PFX "sc520_freq: " |
bf6fc9fd DJ |
33 | |
34 | static struct cpufreq_frequency_table sc520_freq_table[] = { | |
35 | {0x01, 100000}, | |
36 | {0x02, 133000}, | |
37 | {0, CPUFREQ_TABLE_END}, | |
38 | }; | |
39 | ||
40 | static unsigned int sc520_freq_get_cpu_frequency(unsigned int cpu) | |
41 | { | |
42 | u8 clockspeed_reg = *cpuctl; | |
43 | ||
44 | switch (clockspeed_reg & 0x03) { | |
45 | default: | |
6072ace4 DJ |
46 | printk(KERN_ERR PFX "error: cpuctl register has unexpected " |
47 | "value %02x\n", clockspeed_reg); | |
bf6fc9fd DJ |
48 | case 0x01: |
49 | return 100000; | |
50 | case 0x02: | |
51 | return 133000; | |
52 | } | |
53 | } | |
54 | ||
6072ace4 | 55 | static void sc520_freq_set_cpu_state(unsigned int state) |
bf6fc9fd DJ |
56 | { |
57 | ||
58 | struct cpufreq_freqs freqs; | |
59 | u8 clockspeed_reg; | |
60 | ||
61 | freqs.old = sc520_freq_get_cpu_frequency(0); | |
62 | freqs.new = sc520_freq_table[state].frequency; | |
63 | freqs.cpu = 0; /* AMD Elan is UP */ | |
64 | ||
65 | cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); | |
66 | ||
2d06d8c4 | 67 | pr_debug("attempting to set frequency to %i kHz\n", |
bf6fc9fd DJ |
68 | sc520_freq_table[state].frequency); |
69 | ||
70 | local_irq_disable(); | |
71 | ||
72 | clockspeed_reg = *cpuctl & ~0x03; | |
73 | *cpuctl = clockspeed_reg | sc520_freq_table[state].index; | |
74 | ||
75 | local_irq_enable(); | |
76 | ||
77 | cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); | |
78 | }; | |
79 | ||
6072ace4 | 80 | static int sc520_freq_verify(struct cpufreq_policy *policy) |
bf6fc9fd DJ |
81 | { |
82 | return cpufreq_frequency_table_verify(policy, &sc520_freq_table[0]); | |
83 | } | |
84 | ||
6072ace4 | 85 | static int sc520_freq_target(struct cpufreq_policy *policy, |
bf6fc9fd DJ |
86 | unsigned int target_freq, |
87 | unsigned int relation) | |
88 | { | |
89 | unsigned int newstate = 0; | |
90 | ||
6072ace4 DJ |
91 | if (cpufreq_frequency_table_target(policy, sc520_freq_table, |
92 | target_freq, relation, &newstate)) | |
bf6fc9fd DJ |
93 | return -EINVAL; |
94 | ||
95 | sc520_freq_set_cpu_state(newstate); | |
96 | ||
97 | return 0; | |
98 | } | |
99 | ||
100 | ||
101 | /* | |
102 | * Module init and exit code | |
103 | */ | |
104 | ||
105 | static int sc520_freq_cpu_init(struct cpufreq_policy *policy) | |
106 | { | |
92cb7612 | 107 | struct cpuinfo_x86 *c = &cpu_data(0); |
bf6fc9fd DJ |
108 | int result; |
109 | ||
110 | /* capability check */ | |
111 | if (c->x86_vendor != X86_VENDOR_AMD || | |
112 | c->x86 != 4 || c->x86_model != 9) | |
113 | return -ENODEV; | |
114 | ||
115 | /* cpuinfo and default policy values */ | |
bf6fc9fd DJ |
116 | policy->cpuinfo.transition_latency = 1000000; /* 1ms */ |
117 | policy->cur = sc520_freq_get_cpu_frequency(0); | |
118 | ||
119 | result = cpufreq_frequency_table_cpuinfo(policy, sc520_freq_table); | |
120 | if (result) | |
6072ace4 | 121 | return result; |
bf6fc9fd DJ |
122 | |
123 | cpufreq_frequency_table_get_attr(sc520_freq_table, policy->cpu); | |
124 | ||
125 | return 0; | |
126 | } | |
127 | ||
128 | ||
129 | static int sc520_freq_cpu_exit(struct cpufreq_policy *policy) | |
130 | { | |
131 | cpufreq_frequency_table_put_attr(policy->cpu); | |
132 | return 0; | |
133 | } | |
134 | ||
135 | ||
6072ace4 | 136 | static struct freq_attr *sc520_freq_attr[] = { |
bf6fc9fd DJ |
137 | &cpufreq_freq_attr_scaling_available_freqs, |
138 | NULL, | |
139 | }; | |
140 | ||
141 | ||
221dee28 | 142 | static struct cpufreq_driver sc520_freq_driver = { |
bf6fc9fd DJ |
143 | .get = sc520_freq_get_cpu_frequency, |
144 | .verify = sc520_freq_verify, | |
145 | .target = sc520_freq_target, | |
146 | .init = sc520_freq_cpu_init, | |
147 | .exit = sc520_freq_cpu_exit, | |
148 | .name = "sc520_freq", | |
149 | .owner = THIS_MODULE, | |
150 | .attr = sc520_freq_attr, | |
151 | }; | |
152 | ||
153 | ||
154 | static int __init sc520_freq_init(void) | |
155 | { | |
92cb7612 | 156 | struct cpuinfo_x86 *c = &cpu_data(0); |
3e74341c | 157 | int err; |
bf6fc9fd DJ |
158 | |
159 | /* Test if we have the right hardware */ | |
6072ace4 DJ |
160 | if (c->x86_vendor != X86_VENDOR_AMD || |
161 | c->x86 != 4 || c->x86_model != 9) { | |
2d06d8c4 | 162 | pr_debug("no Elan SC520 processor found!\n"); |
bf6fc9fd DJ |
163 | return -ENODEV; |
164 | } | |
165 | cpuctl = ioremap((unsigned long)(MMCR_BASE + OFFS_CPUCTL), 1); | |
6072ace4 | 166 | if (!cpuctl) { |
bf6fc9fd DJ |
167 | printk(KERN_ERR "sc520_freq: error: failed to remap memory\n"); |
168 | return -ENOMEM; | |
169 | } | |
170 | ||
3e74341c AL |
171 | err = cpufreq_register_driver(&sc520_freq_driver); |
172 | if (err) | |
173 | iounmap(cpuctl); | |
174 | ||
175 | return err; | |
bf6fc9fd DJ |
176 | } |
177 | ||
178 | ||
179 | static void __exit sc520_freq_exit(void) | |
180 | { | |
181 | cpufreq_unregister_driver(&sc520_freq_driver); | |
182 | iounmap(cpuctl); | |
183 | } | |
184 | ||
185 | ||
186 | MODULE_LICENSE("GPL"); | |
187 | MODULE_AUTHOR("Sean Young <sean@mess.org>"); | |
188 | MODULE_DESCRIPTION("cpufreq driver for AMD's Elan sc520 CPU"); | |
189 | ||
190 | module_init(sc520_freq_init); | |
191 | module_exit(sc520_freq_exit); | |
192 |