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https://github.com/edk2-porting/linux-next.git
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62027aea23
useful for disabling cpuidle to fall back to architecture-default idle loop cpuidle drivers and governors will fail to register. on x86 they'll say so: intel_idle: intel_idle yielding to (null) ACPI: acpi_idle yielding to (null) Signed-off-by: Len Brown <len.brown@intel.com>
142 lines
3.2 KiB
C
142 lines
3.2 KiB
C
/*
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* governor.c - governor support
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*
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* (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
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* Shaohua Li <shaohua.li@intel.com>
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* Adam Belay <abelay@novell.com>
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*
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* This code is licenced under the GPL.
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*/
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#include <linux/mutex.h>
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#include <linux/module.h>
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#include <linux/cpuidle.h>
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#include "cpuidle.h"
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LIST_HEAD(cpuidle_governors);
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struct cpuidle_governor *cpuidle_curr_governor;
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/**
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* __cpuidle_find_governor - finds a governor of the specified name
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* @str: the name
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*
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* Must be called with cpuidle_lock acquired.
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*/
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static struct cpuidle_governor * __cpuidle_find_governor(const char *str)
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{
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struct cpuidle_governor *gov;
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list_for_each_entry(gov, &cpuidle_governors, governor_list)
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if (!strnicmp(str, gov->name, CPUIDLE_NAME_LEN))
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return gov;
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return NULL;
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}
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/**
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* cpuidle_switch_governor - changes the governor
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* @gov: the new target governor
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*
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* NOTE: "gov" can be NULL to specify disabled
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* Must be called with cpuidle_lock acquired.
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*/
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int cpuidle_switch_governor(struct cpuidle_governor *gov)
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{
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struct cpuidle_device *dev;
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if (gov == cpuidle_curr_governor)
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return 0;
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cpuidle_uninstall_idle_handler();
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if (cpuidle_curr_governor) {
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list_for_each_entry(dev, &cpuidle_detected_devices, device_list)
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cpuidle_disable_device(dev);
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module_put(cpuidle_curr_governor->owner);
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}
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cpuidle_curr_governor = gov;
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if (gov) {
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if (!try_module_get(cpuidle_curr_governor->owner))
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return -EINVAL;
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list_for_each_entry(dev, &cpuidle_detected_devices, device_list)
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cpuidle_enable_device(dev);
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cpuidle_install_idle_handler();
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printk(KERN_INFO "cpuidle: using governor %s\n", gov->name);
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}
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return 0;
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}
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/**
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* cpuidle_register_governor - registers a governor
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* @gov: the governor
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*/
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int cpuidle_register_governor(struct cpuidle_governor *gov)
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{
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int ret = -EEXIST;
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if (!gov || !gov->select)
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return -EINVAL;
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if (cpuidle_disabled())
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return -ENODEV;
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mutex_lock(&cpuidle_lock);
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if (__cpuidle_find_governor(gov->name) == NULL) {
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ret = 0;
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list_add_tail(&gov->governor_list, &cpuidle_governors);
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if (!cpuidle_curr_governor ||
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cpuidle_curr_governor->rating < gov->rating)
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cpuidle_switch_governor(gov);
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}
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mutex_unlock(&cpuidle_lock);
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return ret;
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}
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/**
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* cpuidle_replace_governor - find a replacement governor
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* @exclude_rating: the rating that will be skipped while looking for
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* new governor.
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*/
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static struct cpuidle_governor *cpuidle_replace_governor(int exclude_rating)
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{
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struct cpuidle_governor *gov;
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struct cpuidle_governor *ret_gov = NULL;
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unsigned int max_rating = 0;
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list_for_each_entry(gov, &cpuidle_governors, governor_list) {
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if (gov->rating == exclude_rating)
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continue;
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if (gov->rating > max_rating) {
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max_rating = gov->rating;
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ret_gov = gov;
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}
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}
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return ret_gov;
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}
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/**
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* cpuidle_unregister_governor - unregisters a governor
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* @gov: the governor
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*/
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void cpuidle_unregister_governor(struct cpuidle_governor *gov)
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{
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if (!gov)
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return;
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mutex_lock(&cpuidle_lock);
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if (gov == cpuidle_curr_governor) {
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struct cpuidle_governor *new_gov;
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new_gov = cpuidle_replace_governor(gov->rating);
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cpuidle_switch_governor(new_gov);
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}
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list_del(&gov->governor_list);
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mutex_unlock(&cpuidle_lock);
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}
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