drivers/macintosh/windfarm_cpufreq_clamp.c

   1 #include <linux/config.h>
   2 #include <linux/types.h>
   3 #include <linux/errno.h>
   4 #include <linux/kernel.h>
   5 #include <linux/delay.h>
   6 #include <linux/slab.h>
   7 #include <linux/init.h>
   8 #include <linux/wait.h>
   9 #include <linux/cpufreq.h>
  10
  11 #include "windfarm.h"
  12
  13 #define VERSION "0.3"
  14
  15 static int clamped;
  16 static struct wf_control *clamp_control;
  17
  18 static int clamp_notifier_call(struct notifier_block *self,
  19                                unsigned long event, void *data)
  20 {
  21         struct cpufreq_policy *p = data;
  22         unsigned long max_freq;
  23
  24         if (event != CPUFREQ_ADJUST)
  25                 return 0;
  26
  27         max_freq = clamped ? (p->cpuinfo.min_freq) : (p->cpuinfo.max_freq);
  28         cpufreq_verify_within_limits(p, 0, max_freq);
  29
  30         return 0;
  31 }
  32
  33 static struct notifier_block clamp_notifier = {
  34         .notifier_call = clamp_notifier_call,
  35 };
  36
  37 static int clamp_set(struct wf_control *ct, s32 value)
  38 {
  39         if (value)
  40                 printk(KERN_INFO "windfarm: Clamping CPU frequency to "
  41                        "minimum !\n");
  42         else
  43                 printk(KERN_INFO "windfarm: CPU frequency unclamped !\n");
  44         clamped = value;
  45         cpufreq_update_policy(0);
  46         return 0;
  47 }
  48
  49 static int clamp_get(struct wf_control *ct, s32 *value)
  50 {
  51         *value = clamped;
  52         return 0;
  53 }
  54
  55 static s32 clamp_min(struct wf_control *ct)
  56 {
  57         return 0;
  58 }
  59
  60 static s32 clamp_max(struct wf_control *ct)
  61 {
  62         return 1;
  63 }
  64
  65 static struct wf_control_ops clamp_ops = {
  66         .set_value      = clamp_set,
  67         .get_value      = clamp_get,
  68         .get_min        = clamp_min,
  69         .get_max        = clamp_max,
  70         .owner          = THIS_MODULE,
  71 };
  72
  73 static int __init wf_cpufreq_clamp_init(void)
  74 {
  75         struct wf_control *clamp;
  76
  77         clamp = kmalloc(sizeof(struct wf_control), GFP_KERNEL);
  78         if (clamp == NULL)
  79                 return -ENOMEM;
  80         cpufreq_register_notifier(&clamp_notifier, CPUFREQ_POLICY_NOTIFIER);
  81         clamp->ops = &clamp_ops;
  82         clamp->name = "cpufreq-clamp";
  83         if (wf_register_control(clamp))
  84                 goto fail;
  85         clamp_control = clamp;
  86         return 0;
  87  fail:
  88         kfree(clamp);
  89         return -ENODEV;
  90 }
  91
  92 static void __exit wf_cpufreq_clamp_exit(void)
  93 {
  94         if (clamp_control)
  95                 wf_unregister_control(clamp_control);
  96 }
  97
  98
  99 module_init(wf_cpufreq_clamp_init);
 100 module_exit(wf_cpufreq_clamp_exit);
 101
 102 MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
 103 MODULE_DESCRIPTION("CPU frequency clamp for PowerMacs thermal control");
 104 MODULE_LICENSE("GPL");
 105