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 <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
  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
  41 static int clamp_get(struct wf_control *ct, s32 *value)
  42 {
  43         *value = clamped;
  44         return 0;
  45 }
  46
  47 static s32 clamp_min(struct wf_control *ct)
  48 {
  49         return 0;
  50 }
  51
  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
  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
 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