/* * governor.c - governor support * * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> * Shaohua Li <shaohua.li@intel.com> * Adam Belay <abelay@novell.com> * * This code is licenced under the GPL. */ #include <linux/mutex.h> #include <linux/module.h> #include <linux/cpuidle.h> #include "cpuidle.h" LIST_HEAD(cpuidle_governors); struct cpuidle_governor *cpuidle_curr_governor; /** * __cpuidle_find_governor - finds a governor of the specified name * @str: the name * * Must be called with cpuidle_lock aquired. */ static struct cpuidle_governor * __cpuidle_find_governor(const char *str) { struct cpuidle_governor *gov; list_for_each_entry(gov, &cpuidle_governors, governor_list) if (!strnicmp(str, gov->name, CPUIDLE_NAME_LEN)) return gov; return NULL; } /** * cpuidle_switch_governor - changes the governor * @gov: the new target governor * * NOTE: "gov" can be NULL to specify disabled * Must be called with cpuidle_lock aquired. */ int cpuidle_switch_governor(struct cpuidle_governor *gov) { struct cpuidle_device *dev; if (gov == cpuidle_curr_governor) return 0; cpuidle_uninstall_idle_handler(); if (cpuidle_curr_governor) { list_for_each_entry(dev, &cpuidle_detected_devices, device_list) cpuidle_disable_device(dev); module_put(cpuidle_curr_governor->owner); } cpuidle_curr_governor = gov; if (gov) { if (!try_module_get(cpuidle_curr_governor->owner)) return -EINVAL; list_for_each_entry(dev, &cpuidle_detected_devices, device_list) cpuidle_enable_device(dev); cpuidle_install_idle_handler(); printk(KERN_INFO "cpuidle: using governor %s\n", gov->name); } return 0; } /** * cpuidle_register_governor - registers a governor * @gov: the governor */ int cpuidle_register_governor(struct cpuidle_governor *gov) { int ret = -EEXIST; if (!gov || !gov->select) return -EINVAL; mutex_lock(&cpuidle_lock); if (__cpuidle_find_governor(gov->name) == NULL) { ret = 0; list_add_tail(&gov->governor_list, &cpuidle_governors); if (!cpuidle_curr_governor || cpuidle_curr_governor->rating < gov->rating) cpuidle_switch_governor(gov); } mutex_unlock(&cpuidle_lock); return ret; } /** * cpuidle_replace_governor - find a replacement governor * @exclude_rating: the rating that will be skipped while looking for * new governor. */ static struct cpuidle_governor *cpuidle_replace_governor(int exclude_rating) { struct cpuidle_governor *gov; struct cpuidle_governor *ret_gov = NULL; unsigned int max_rating = 0; list_for_each_entry(gov, &cpuidle_governors, governor_list) { if (gov->rating == exclude_rating) continue; if (gov->rating > max_rating) { max_rating = gov->rating; ret_gov = gov; } } return ret_gov; } /** * cpuidle_unregister_governor - unregisters a governor * @gov: the governor */ void cpuidle_unregister_governor(struct cpuidle_governor *gov) { if (!gov) return; mutex_lock(&cpuidle_lock); if (gov == cpuidle_curr_governor) { struct cpuidle_governor *new_gov; new_gov = cpuidle_replace_governor(gov->rating); cpuidle_switch_governor(new_gov); } list_del(&gov->governor_list); mutex_unlock(&cpuidle_lock); }