devfreq

devfreq 是指频率电源可以动态调节的设备，可以添加不同设备及不同govvernor ;

devfreq 框架和opp(operating performance point) 频率电源对 devices driver 通过 devfreq profile 交互

devfreq_dev_profile

include/linux/devfreq.h

devfreq_governor 与 devfreq 框架交互数据结构

drivers/devfreq/governor.h

devfreq opp 设备核心数据结构，将opp device driver 的 devfreq_dev_profile 和 governor 的devfreq_governor 关联起来，并通过设备驱动模型中device 类为用户控件提供接口。

 struct devfreq {
177  	struct list_head node;
178  
179  	struct mutex lock;
180  	struct device dev;
181  	struct devfreq_dev_profile *profile;
182  	const struct devfreq_governor *governor;
183  	struct opp_table *opp_table;
184  	struct notifier_block nb;
185  	struct delayed_work work;
186  
187  	unsigned long previous_freq;
188  	struct devfreq_dev_status last_status;
189  
190  	void *data; /* private data for governors */
191  
192  	struct dev_pm_qos_request user_min_freq_req;
193  	struct dev_pm_qos_request user_max_freq_req;
194  	unsigned long scaling_min_freq;
195  	unsigned long scaling_max_freq;
196  	bool stop_polling;
197  
198  	unsigned long suspend_freq;
199  	unsigned long resume_freq;
200  	atomic_t suspend_count;
201  
202  	/* information for device frequency transitions */
203  	struct devfreq_stats stats;
204  
205  	struct srcu_notifier_head transition_notifier_list;
206  
207  	/* Pointer to the cooling device if used for thermal mitigation */
208  	struct thermal_cooling_device *cdev;
209  
210  	struct notifier_block nb_min;
211  	struct notifier_block nb_max;
212  };
213