120 lines · c
1/*2 * governor.c - governor support3 *4 * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>5 * Shaohua Li <shaohua.li@intel.com>6 * Adam Belay <abelay@novell.com>7 *8 * This code is licenced under the GPL.9 */10 11#include <linux/cpu.h>12#include <linux/cpuidle.h>13#include <linux/mutex.h>14#include <linux/module.h>15#include <linux/pm_qos.h>16 17#include "cpuidle.h"18 19char param_governor[CPUIDLE_NAME_LEN];20 21LIST_HEAD(cpuidle_governors);22struct cpuidle_governor *cpuidle_curr_governor;23struct cpuidle_governor *cpuidle_prev_governor;24 25/**26 * cpuidle_find_governor - finds a governor of the specified name27 * @str: the name28 *29 * Must be called with cpuidle_lock acquired.30 */31struct cpuidle_governor *cpuidle_find_governor(const char *str)32{33 struct cpuidle_governor *gov;34 35 list_for_each_entry(gov, &cpuidle_governors, governor_list)36 if (!strncasecmp(str, gov->name, CPUIDLE_NAME_LEN))37 return gov;38 39 return NULL;40}41 42/**43 * cpuidle_switch_governor - changes the governor44 * @gov: the new target governor45 * Must be called with cpuidle_lock acquired.46 */47int cpuidle_switch_governor(struct cpuidle_governor *gov)48{49 struct cpuidle_device *dev;50 51 if (!gov)52 return -EINVAL;53 54 if (gov == cpuidle_curr_governor)55 return 0;56 57 cpuidle_uninstall_idle_handler();58 59 if (cpuidle_curr_governor) {60 list_for_each_entry(dev, &cpuidle_detected_devices, device_list)61 cpuidle_disable_device(dev);62 }63 64 cpuidle_curr_governor = gov;65 66 list_for_each_entry(dev, &cpuidle_detected_devices, device_list)67 cpuidle_enable_device(dev);68 69 cpuidle_install_idle_handler();70 pr_info("cpuidle: using governor %s\n", gov->name);71 72 return 0;73}74 75/**76 * cpuidle_register_governor - registers a governor77 * @gov: the governor78 */79int cpuidle_register_governor(struct cpuidle_governor *gov)80{81 int ret = -EEXIST;82 83 if (!gov || !gov->select)84 return -EINVAL;85 86 if (cpuidle_disabled())87 return -ENODEV;88 89 mutex_lock(&cpuidle_lock);90 if (cpuidle_find_governor(gov->name) == NULL) {91 ret = 0;92 list_add_tail(&gov->governor_list, &cpuidle_governors);93 if (!cpuidle_curr_governor ||94 !strncasecmp(param_governor, gov->name, CPUIDLE_NAME_LEN) ||95 (cpuidle_curr_governor->rating < gov->rating &&96 strncasecmp(param_governor, cpuidle_curr_governor->name,97 CPUIDLE_NAME_LEN)))98 cpuidle_switch_governor(gov);99 }100 mutex_unlock(&cpuidle_lock);101 102 return ret;103}104 105/**106 * cpuidle_governor_latency_req - Compute a latency constraint for CPU107 * @cpu: Target CPU108 */109s64 cpuidle_governor_latency_req(unsigned int cpu)110{111 struct device *device = get_cpu_device(cpu);112 int device_req = dev_pm_qos_raw_resume_latency(device);113 int global_req = cpu_latency_qos_limit();114 115 if (device_req > global_req)116 device_req = global_req;117 118 return (s64)device_req * NSEC_PER_USEC;119}120