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
19 static int clamped;
20 static struct wf_control *clamp_control;
21 static struct freq_qos_request qos_req;
22 static unsigned int min_freq, max_freq;
23
clamp_set(struct wf_control * ct,s32 value)24 static 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
clamp_get(struct wf_control * ct,s32 * value)41 static int clamp_get(struct wf_control *ct, s32 *value)
42 {
43 *value = clamped;
44 return 0;
45 }
46
clamp_min(struct wf_control * ct)47 static s32 clamp_min(struct wf_control *ct)
48 {
49 return 0;
50 }
51
clamp_max(struct wf_control * ct)52 static s32 clamp_max(struct wf_control *ct)
53 {
54 return 1;
55 }
56
57 static 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
wf_cpufreq_clamp_init(void)65 static 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
wf_cpufreq_clamp_exit(void)121 static 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
130 module_init(wf_cpufreq_clamp_init);
131 module_exit(wf_cpufreq_clamp_exit);
132
133 MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
134 MODULE_DESCRIPTION("CPU frequency clamp for PowerMacs thermal control");
135 MODULE_LICENSE("GPL");
136
137