1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun #include <linux/types.h>
3*4882a593Smuzhiyun #include <linux/errno.h>
4*4882a593Smuzhiyun #include <linux/kernel.h>
5*4882a593Smuzhiyun #include <linux/delay.h>
6*4882a593Smuzhiyun #include <linux/pm_qos.h>
7*4882a593Smuzhiyun #include <linux/slab.h>
8*4882a593Smuzhiyun #include <linux/init.h>
9*4882a593Smuzhiyun #include <linux/wait.h>
10*4882a593Smuzhiyun #include <linux/cpu.h>
11*4882a593Smuzhiyun #include <linux/cpufreq.h>
12*4882a593Smuzhiyun
13*4882a593Smuzhiyun #include <asm/prom.h>
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun #include "windfarm.h"
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun #define VERSION "0.3"
18*4882a593Smuzhiyun
19*4882a593Smuzhiyun static int clamped;
20*4882a593Smuzhiyun static struct wf_control *clamp_control;
21*4882a593Smuzhiyun static struct freq_qos_request qos_req;
22*4882a593Smuzhiyun static unsigned int min_freq, max_freq;
23*4882a593Smuzhiyun
clamp_set(struct wf_control * ct,s32 value)24*4882a593Smuzhiyun static int clamp_set(struct wf_control *ct, s32 value)
25*4882a593Smuzhiyun {
26*4882a593Smuzhiyun unsigned int freq;
27*4882a593Smuzhiyun
28*4882a593Smuzhiyun if (value) {
29*4882a593Smuzhiyun freq = min_freq;
30*4882a593Smuzhiyun printk(KERN_INFO "windfarm: Clamping CPU frequency to "
31*4882a593Smuzhiyun "minimum !\n");
32*4882a593Smuzhiyun } else {
33*4882a593Smuzhiyun freq = max_freq;
34*4882a593Smuzhiyun printk(KERN_INFO "windfarm: CPU frequency unclamped !\n");
35*4882a593Smuzhiyun }
36*4882a593Smuzhiyun clamped = value;
37*4882a593Smuzhiyun
38*4882a593Smuzhiyun return freq_qos_update_request(&qos_req, freq);
39*4882a593Smuzhiyun }
40*4882a593Smuzhiyun
clamp_get(struct wf_control * ct,s32 * value)41*4882a593Smuzhiyun static int clamp_get(struct wf_control *ct, s32 *value)
42*4882a593Smuzhiyun {
43*4882a593Smuzhiyun *value = clamped;
44*4882a593Smuzhiyun return 0;
45*4882a593Smuzhiyun }
46*4882a593Smuzhiyun
clamp_min(struct wf_control * ct)47*4882a593Smuzhiyun static s32 clamp_min(struct wf_control *ct)
48*4882a593Smuzhiyun {
49*4882a593Smuzhiyun return 0;
50*4882a593Smuzhiyun }
51*4882a593Smuzhiyun
clamp_max(struct wf_control * ct)52*4882a593Smuzhiyun static s32 clamp_max(struct wf_control *ct)
53*4882a593Smuzhiyun {
54*4882a593Smuzhiyun return 1;
55*4882a593Smuzhiyun }
56*4882a593Smuzhiyun
57*4882a593Smuzhiyun static const struct wf_control_ops clamp_ops = {
58*4882a593Smuzhiyun .set_value = clamp_set,
59*4882a593Smuzhiyun .get_value = clamp_get,
60*4882a593Smuzhiyun .get_min = clamp_min,
61*4882a593Smuzhiyun .get_max = clamp_max,
62*4882a593Smuzhiyun .owner = THIS_MODULE,
63*4882a593Smuzhiyun };
64*4882a593Smuzhiyun
wf_cpufreq_clamp_init(void)65*4882a593Smuzhiyun static int __init wf_cpufreq_clamp_init(void)
66*4882a593Smuzhiyun {
67*4882a593Smuzhiyun struct cpufreq_policy *policy;
68*4882a593Smuzhiyun struct wf_control *clamp;
69*4882a593Smuzhiyun struct device *dev;
70*4882a593Smuzhiyun int ret;
71*4882a593Smuzhiyun
72*4882a593Smuzhiyun policy = cpufreq_cpu_get(0);
73*4882a593Smuzhiyun if (!policy) {
74*4882a593Smuzhiyun pr_warn("%s: cpufreq policy not found cpu0\n", __func__);
75*4882a593Smuzhiyun return -EPROBE_DEFER;
76*4882a593Smuzhiyun }
77*4882a593Smuzhiyun
78*4882a593Smuzhiyun min_freq = policy->cpuinfo.min_freq;
79*4882a593Smuzhiyun max_freq = policy->cpuinfo.max_freq;
80*4882a593Smuzhiyun
81*4882a593Smuzhiyun ret = freq_qos_add_request(&policy->constraints, &qos_req, FREQ_QOS_MAX,
82*4882a593Smuzhiyun max_freq);
83*4882a593Smuzhiyun
84*4882a593Smuzhiyun cpufreq_cpu_put(policy);
85*4882a593Smuzhiyun
86*4882a593Smuzhiyun if (ret < 0) {
87*4882a593Smuzhiyun pr_err("%s: Failed to add freq constraint (%d)\n", __func__,
88*4882a593Smuzhiyun ret);
89*4882a593Smuzhiyun return ret;
90*4882a593Smuzhiyun }
91*4882a593Smuzhiyun
92*4882a593Smuzhiyun dev = get_cpu_device(0);
93*4882a593Smuzhiyun if (unlikely(!dev)) {
94*4882a593Smuzhiyun pr_warn("%s: No cpu device for cpu0\n", __func__);
95*4882a593Smuzhiyun ret = -ENODEV;
96*4882a593Smuzhiyun goto fail;
97*4882a593Smuzhiyun }
98*4882a593Smuzhiyun
99*4882a593Smuzhiyun clamp = kmalloc(sizeof(struct wf_control), GFP_KERNEL);
100*4882a593Smuzhiyun if (clamp == NULL) {
101*4882a593Smuzhiyun ret = -ENOMEM;
102*4882a593Smuzhiyun goto fail;
103*4882a593Smuzhiyun }
104*4882a593Smuzhiyun
105*4882a593Smuzhiyun clamp->ops = &clamp_ops;
106*4882a593Smuzhiyun clamp->name = "cpufreq-clamp";
107*4882a593Smuzhiyun ret = wf_register_control(clamp);
108*4882a593Smuzhiyun if (ret)
109*4882a593Smuzhiyun goto free;
110*4882a593Smuzhiyun
111*4882a593Smuzhiyun clamp_control = clamp;
112*4882a593Smuzhiyun return 0;
113*4882a593Smuzhiyun
114*4882a593Smuzhiyun free:
115*4882a593Smuzhiyun kfree(clamp);
116*4882a593Smuzhiyun fail:
117*4882a593Smuzhiyun freq_qos_remove_request(&qos_req);
118*4882a593Smuzhiyun return ret;
119*4882a593Smuzhiyun }
120*4882a593Smuzhiyun
wf_cpufreq_clamp_exit(void)121*4882a593Smuzhiyun static void __exit wf_cpufreq_clamp_exit(void)
122*4882a593Smuzhiyun {
123*4882a593Smuzhiyun if (clamp_control) {
124*4882a593Smuzhiyun wf_unregister_control(clamp_control);
125*4882a593Smuzhiyun freq_qos_remove_request(&qos_req);
126*4882a593Smuzhiyun }
127*4882a593Smuzhiyun }
128*4882a593Smuzhiyun
129*4882a593Smuzhiyun
130*4882a593Smuzhiyun module_init(wf_cpufreq_clamp_init);
131*4882a593Smuzhiyun module_exit(wf_cpufreq_clamp_exit);
132*4882a593Smuzhiyun
133*4882a593Smuzhiyun MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
134*4882a593Smuzhiyun MODULE_DESCRIPTION("CPU frequency clamp for PowerMacs thermal control");
135*4882a593Smuzhiyun MODULE_LICENSE("GPL");
136*4882a593Smuzhiyun
137