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