/* * 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/cpu.h> #include <linux/cpuidle.h> #include <linux/mutex.h> #include <linux/module.h> #include <linux/pm_qos.h> #include "cpuidle.h" char param_governor[CPUIDLE_NAME_LEN]; 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 acquired. */ static struct cpuidle_governor * __cpuidle_find_governor(const char *str) { struct cpuidle_governor *gov; list_for_each_entry(gov, &cpuidle_governors, governor_list) if (!strncasecmp(str, gov->name, CPUIDLE_NAME_LEN)) return gov; return NULL; } /** * cpuidle_switch_governor - changes the governor * @gov: the new target governor * Must be called with cpuidle_lock acquired. */ int cpuidle_switch_governor(struct cpuidle_governor *gov) { struct cpuidle_device *dev; if (!gov) return -EINVAL; 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); } cpuidle_curr_governor = gov; if (gov) { 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; if (cpuidle_disabled()) return -ENODEV; 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 || !strncasecmp(param_governor, gov->name, CPUIDLE_NAME_LEN) || (cpuidle_curr_governor->rating < gov->rating && strncasecmp(param_governor, cpuidle_curr_governor->name, CPUIDLE_NAME_LEN))) cpuidle_switch_governor(gov); } mutex_unlock(&cpuidle_lock); return ret; } /** * cpuidle_governor_latency_req - Compute a latency constraint for CPU * @cpu: Target CPU */ int cpuidle_governor_latency_req(unsigned int cpu) { int global_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY); struct device *device = get_cpu_device(cpu); int device_req = dev_pm_qos_raw_read_value(device); return device_req < global_req ? device_req : global_req; }