drivers/macintosh/windfarm_cpufreq_clamp.c

   1 #include <linux/types.h>
   2 #include <linux/errno.h>
   3 #include <linux/kernel.h>
   4 #include <linux/delay.h>
   5 #include <linux/slab.h>
   6 #include <linux/init.h>
   7 #include <linux/wait.h>
   8 #include <linux/cpufreq.h>
   9
  10 #include <asm/prom.h>
  11
  12 #include "windfarm.h"
  13
  14 #define VERSION "0.3"
  15
  16 static int clamped;
  17 static struct wf_control *clamp_control;
  18
  19 static int clamp_notifier_call(struct notifier_block *self,
  20                                unsigned long event, void *data)
  21 {
  22         struct cpufreq_policy *p = data;
  23         unsigned long max_freq;
  24
  25         if (event != CPUFREQ_ADJUST)
  26                 return 0;
  27
  28         max_freq = clamped ? (p->cpuinfo.min_freq) : (p->cpuinfo.max_freq);
  29         cpufreq_verify_within_limits(p, 0, max_freq);
  30
  31         return 0;
  32 }
  33
  34 static struct notifier_block clamp_notifier = {
  35         .notifier_call = clamp_notifier_call,
  36 };
  37
  38 static int clamp_set(struct wf_control *ct, s32 value)
  39 {
  40         if (value)
  41                 printk(KERN_INFO "windfarm: Clamping CPU frequency to "
  42                        "minimum !\n");
  43         else
  44                 printk(KERN_INFO "windfarm: CPU frequency unclamped !\n");
  45         clamped = value;
  46         cpufreq_update_policy(0);
  47         return 0;
  48 }
  49
  50 static int clamp_get(struct wf_control *ct, s32 *value)
  51 {
  52         *value = clamped;
  53         return 0;
  54 }
  55
  56 static s32 clamp_min(struct wf_control *ct)
  57 {
  58         return 0;
  59 }
  60
  61 static s32 clamp_max(struct wf_control *ct)
  62 {
  63         return 1;
  64 }
  65
  66 static const struct wf_control_ops clamp_ops = {
  67         .set_value      = clamp_set,
  68         .get_value      = clamp_get,
  69         .get_min        = clamp_min,
  70         .get_max        = clamp_max,
  71         .owner          = THIS_MODULE,
  72 };
  73
  74 static int __init wf_cpufreq_clamp_init(void)
  75 {
  76         struct wf_control *clamp;
  77
  78         clamp = kmalloc(sizeof(struct wf_control), GFP_KERNEL);
  79         if (clamp == NULL)
  80                 return -ENOMEM;
  81         cpufreq_register_notifier(&clamp_notifier, CPUFREQ_POLICY_NOTIFIER);
  82         clamp->ops = &clamp_ops;
  83         clamp->name = "cpufreq-clamp";
  84         if (wf_register_control(clamp))
  85                 goto fail;
  86         clamp_control = clamp;
  87         return 0;
  88  fail:
  89         kfree(clamp);
  90         return -ENODEV;
  91 }
  92
  93 static void __exit wf_cpufreq_clamp_exit(void)
  94 {
  95         if (clamp_control)
  96                 wf_unregister_control(clamp_control);
  97 }
  98
  99
 100 module_init(wf_cpufreq_clamp_init);
 101 module_exit(wf_cpufreq_clamp_exit);
 102
 103 MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
 104 MODULE_DESCRIPTION("CPU frequency clamp for PowerMacs thermal control");
 105 MODULE_LICENSE("GPL");
 106