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
16static int clamped;
17static struct wf_control *clamp_control;
18
19static 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
34static struct notifier_block clamp_notifier = {
35	.notifier_call = clamp_notifier_call,
36};
37
38static 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
50static int clamp_get(struct wf_control *ct, s32 *value)
51{
52	*value = clamped;
53	return 0;
54}
55
56static s32 clamp_min(struct wf_control *ct)
57{
58	return 0;
59}
60
61static s32 clamp_max(struct wf_control *ct)
62{
63	return 1;
64}
65
66static 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
74static 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
93static void __exit wf_cpufreq_clamp_exit(void)
94{
95	if (clamp_control)
96		wf_unregister_control(clamp_control);
97}
98
99
100module_init(wf_cpufreq_clamp_init);
101module_exit(wf_cpufreq_clamp_exit);
102
103MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
104MODULE_DESCRIPTION("CPU frequency clamp for PowerMacs thermal control");
105MODULE_LICENSE("GPL");
106
107