| /* |
| * 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; |
| struct cpuidle_governor *cpuidle_prev_governor; |
| |
| /** |
| * cpuidle_find_governor - finds a governor of the specified name |
| * @str: the name |
| * |
| * Must be called with cpuidle_lock acquired. |
| */ |
| 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_resume_latency(device); |
| |
| return device_req < global_req ? device_req : global_req; |
| } |