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
17 static int clamped;
18 static struct wf_control *clamp_control;
19 static struct freq_qos_request qos_req;
20 static unsigned int min_freq, max_freq;
21
clamp_set(struct wf_control * ct,s32 value)22 static 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
clamp_get(struct wf_control * ct,s32 * value)39 static int clamp_get(struct wf_control *ct, s32 *value)
40 {
41 *value = clamped;
42 return 0;
43 }
44
clamp_min(struct wf_control * ct)45 static s32 clamp_min(struct wf_control *ct)
46 {
47 return 0;
48 }
49
clamp_max(struct wf_control * ct)50 static s32 clamp_max(struct wf_control *ct)
51 {
52 return 1;
53 }
54
55 static 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
wf_cpufreq_clamp_init(void)63 static 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
wf_cpufreq_clamp_exit(void)119 static 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
128 module_init(wf_cpufreq_clamp_init);
129 module_exit(wf_cpufreq_clamp_exit);
130
131 MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
132 MODULE_DESCRIPTION("CPU frequency clamp for PowerMacs thermal control");
133 MODULE_LICENSE("GPL");
134
135