1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/types.h>
3#include <linux/errno.h>
4#include <linux/kernel.h>
5#include <linux/delay.h>
6#include <linux/pm_qos.h>
7#include <linux/slab.h>
8#include <linux/init.h>
9#include <linux/wait.h>
10#include <linux/cpu.h>
11#include <linux/cpufreq.h>
12
13#include <asm/prom.h>
14
15#include "windfarm.h"
16
17#define VERSION "0.3"
18
19static int clamped;
20static struct wf_control *clamp_control;
21static struct freq_qos_request qos_req;
22static unsigned int min_freq, max_freq;
23
24static int clamp_set(struct wf_control *ct, s32 value)
25{
26	unsigned int freq;
27
28	if (value) {
29		freq = min_freq;
30		printk(KERN_INFO "windfarm: Clamping CPU frequency to "
31		       "minimum !\n");
32	} else {
33		freq = max_freq;
34		printk(KERN_INFO "windfarm: CPU frequency unclamped !\n");
35	}
36	clamped = value;
37
38	return freq_qos_update_request(&qos_req, freq);
39}
40
41static int clamp_get(struct wf_control *ct, s32 *value)
42{
43	*value = clamped;
44	return 0;
45}
46
47static s32 clamp_min(struct wf_control *ct)
48{
49	return 0;
50}
51
52static s32 clamp_max(struct wf_control *ct)
53{
54	return 1;
55}
56
57static const struct wf_control_ops clamp_ops = {
58	.set_value	= clamp_set,
59	.get_value	= clamp_get,
60	.get_min	= clamp_min,
61	.get_max	= clamp_max,
62	.owner		= THIS_MODULE,
63};
64
65static int __init wf_cpufreq_clamp_init(void)
66{
67	struct cpufreq_policy *policy;
68	struct wf_control *clamp;
69	struct device *dev;
70	int ret;
71
72	policy = cpufreq_cpu_get(0);
73	if (!policy) {
74		pr_warn("%s: cpufreq policy not found cpu0\n", __func__);
75		return -EPROBE_DEFER;
76	}
77
78	min_freq = policy->cpuinfo.min_freq;
79	max_freq = policy->cpuinfo.max_freq;
80
81	ret = freq_qos_add_request(&policy->constraints, &qos_req, FREQ_QOS_MAX,
82				   max_freq);
83
84	cpufreq_cpu_put(policy);
85
86	if (ret < 0) {
87		pr_err("%s: Failed to add freq constraint (%d)\n", __func__,
88		       ret);
89		return ret;
90	}
91
92	dev = get_cpu_device(0);
93	if (unlikely(!dev)) {
94		pr_warn("%s: No cpu device for cpu0\n", __func__);
95		ret = -ENODEV;
96		goto fail;
97	}
98
99	clamp = kmalloc(sizeof(struct wf_control), GFP_KERNEL);
100	if (clamp == NULL) {
101		ret = -ENOMEM;
102		goto fail;
103	}
104
105	clamp->ops = &clamp_ops;
106	clamp->name = "cpufreq-clamp";
107	ret = wf_register_control(clamp);
108	if (ret)
109		goto free;
110
111	clamp_control = clamp;
112	return 0;
113
114 free:
115	kfree(clamp);
116 fail:
117	freq_qos_remove_request(&qos_req);
118	return ret;
119}
120
121static void __exit wf_cpufreq_clamp_exit(void)
122{
123	if (clamp_control) {
124		wf_unregister_control(clamp_control);
125		freq_qos_remove_request(&qos_req);
126	}
127}
128
129
130module_init(wf_cpufreq_clamp_init);
131module_exit(wf_cpufreq_clamp_exit);
132
133MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
134MODULE_DESCRIPTION("CPU frequency clamp for PowerMacs thermal control");
135MODULE_LICENSE("GPL");
136
137