linux/drivers/macintosh/windfarm_cpufreq_clamp.c
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   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
  16static int clamped;
  17static struct wf_control *clamp_control;
  18
  19static 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
  34static struct notifier_block clamp_notifier = {
  35        .notifier_call = clamp_notifier_call,
  36};
  37
  38static 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
  50static int clamp_get(struct wf_control *ct, s32 *value)
  51{
  52        *value = clamped;
  53        return 0;
  54}
  55
  56static s32 clamp_min(struct wf_control *ct)
  57{
  58        return 0;
  59}
  60
  61static s32 clamp_max(struct wf_control *ct)
  62{
  63        return 1;
  64}
  65
  66static 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
  74static int __init wf_cpufreq_clamp_init(void)
  75{
  76        struct wf_control *clamp;
  77
  78        /* Don't register on old machines that use therm_pm72 for now */
  79        if (of_machine_is_compatible("PowerMac7,2") ||
  80            of_machine_is_compatible("PowerMac7,3") ||
  81            of_machine_is_compatible("RackMac3,1"))
  82                return -ENODEV;
  83
  84        clamp = kmalloc(sizeof(struct wf_control), GFP_KERNEL);
  85        if (clamp == NULL)
  86                return -ENOMEM;
  87        cpufreq_register_notifier(&clamp_notifier, CPUFREQ_POLICY_NOTIFIER);
  88        clamp->ops = &clamp_ops;
  89        clamp->name = "cpufreq-clamp";
  90        if (wf_register_control(clamp))
  91                goto fail;
  92        clamp_control = clamp;
  93        return 0;
  94 fail:
  95        kfree(clamp);
  96        return -ENODEV;
  97}
  98
  99static void __exit wf_cpufreq_clamp_exit(void)
 100{
 101        if (clamp_control)
 102                wf_unregister_control(clamp_control);
 103}
 104
 105
 106module_init(wf_cpufreq_clamp_init);
 107module_exit(wf_cpufreq_clamp_exit);
 108
 109MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
 110MODULE_DESCRIPTION("CPU frequency clamp for PowerMacs thermal control");
 111MODULE_LICENSE("GPL");
 112
 113