1 #include <linux/types.h>
2 #include <linux/errno.h>
3 #include <linux/kernel.h>
4 #include <linux/delay.h>
5 #include <linux/slab.h>
6 #include <linux/init.h>
7 #include <linux/wait.h>
8 #include <linux/cpufreq.h>
9
10 #include <asm/prom.h>
11
12 #include "windfarm.h"
13
14 #define VERSION "0.3"
15
16 static int clamped;
17 static struct wf_control *clamp_control;
18
clamp_notifier_call(struct notifier_block * self,unsigned long event,void * data)19 static int clamp_notifier_call(struct notifier_block *self,
20 unsigned long event, void *data)
21 {
22 struct cpufreq_policy *p = data;
23 unsigned long max_freq;
24
25 if (event != CPUFREQ_ADJUST)
26 return 0;
27
28 max_freq = clamped ? (p->cpuinfo.min_freq) : (p->cpuinfo.max_freq);
29 cpufreq_verify_within_limits(p, 0, max_freq);
30
31 return 0;
32 }
33
34 static struct notifier_block clamp_notifier = {
35 .notifier_call = clamp_notifier_call,
36 };
37
clamp_set(struct wf_control * ct,s32 value)38 static int clamp_set(struct wf_control *ct, s32 value)
39 {
40 if (value)
41 printk(KERN_INFO "windfarm: Clamping CPU frequency to "
42 "minimum !\n");
43 else
44 printk(KERN_INFO "windfarm: CPU frequency unclamped !\n");
45 clamped = value;
46 cpufreq_update_policy(0);
47 return 0;
48 }
49
clamp_get(struct wf_control * ct,s32 * value)50 static int clamp_get(struct wf_control *ct, s32 *value)
51 {
52 *value = clamped;
53 return 0;
54 }
55
clamp_min(struct wf_control * ct)56 static s32 clamp_min(struct wf_control *ct)
57 {
58 return 0;
59 }
60
clamp_max(struct wf_control * ct)61 static s32 clamp_max(struct wf_control *ct)
62 {
63 return 1;
64 }
65
66 static const struct wf_control_ops clamp_ops = {
67 .set_value = clamp_set,
68 .get_value = clamp_get,
69 .get_min = clamp_min,
70 .get_max = clamp_max,
71 .owner = THIS_MODULE,
72 };
73
wf_cpufreq_clamp_init(void)74 static int __init wf_cpufreq_clamp_init(void)
75 {
76 struct wf_control *clamp;
77
78 clamp = kmalloc(sizeof(struct wf_control), GFP_KERNEL);
79 if (clamp == NULL)
80 return -ENOMEM;
81 cpufreq_register_notifier(&clamp_notifier, CPUFREQ_POLICY_NOTIFIER);
82 clamp->ops = &clamp_ops;
83 clamp->name = "cpufreq-clamp";
84 if (wf_register_control(clamp))
85 goto fail;
86 clamp_control = clamp;
87 return 0;
88 fail:
89 kfree(clamp);
90 return -ENODEV;
91 }
92
wf_cpufreq_clamp_exit(void)93 static void __exit wf_cpufreq_clamp_exit(void)
94 {
95 if (clamp_control)
96 wf_unregister_control(clamp_control);
97 }
98
99
100 module_init(wf_cpufreq_clamp_init);
101 module_exit(wf_cpufreq_clamp_exit);
102
103 MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
104 MODULE_DESCRIPTION("CPU frequency clamp for PowerMacs thermal control");
105 MODULE_LICENSE("GPL");
106
107
