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 
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 
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 
50 static int clamp_get(struct wf_control *ct, s32 *value)
51 {
52 	*value = clamped;
53 	return 0;
54 }
55 
56 static s32 clamp_min(struct wf_control *ct)
57 {
58 	return 0;
59 }
60 
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 
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 
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