drivers/macintosh/windfarm_cpufreq_clamp.c

   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
  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
  39 static int clamp_get(struct wf_control *ct, s32 *value)
  40 {
  41         *value = clamped;
  42         return 0;
  43 }
  44
  45 static s32 clamp_min(struct wf_control *ct)
  46 {
  47         return 0;
  48 }
  49
  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
  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
 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