STRUCT DEVFREQ(9)

okay bestie, this is struct devfreq(9) from the Kernel API Manual — the whole vibe is the Device devfreq structure, and we're getting into every lil field. 💅✨

✨ NAME ✨

struct devfreq — Device devfreq structure. periodt.

🌈 SYNOPSIS 🌈

struct devfreq {
    struct list_head node;
    struct mutex lock;
    struct device dev;
    struct devfreq_dev_profile *profile;
    const struct devfreq_governor *governor;
    struct opp_table *opp_table;
    struct notifier_block nb;
    struct delayed_work work;
    unsigned long *freq_table;
    unsigned int max_state;
    unsigned long previous_freq;
    struct devfreq_dev_status last_status;
    void *data;
    void *governor_data;
    struct dev_pm_qos_request user_min_freq_req;
    struct dev_pm_qos_request user_max_freq_req;
    unsigned long scaling_min_freq;
    unsigned long scaling_max_freq;
    bool stop_polling;
    unsigned long suspend_freq;
    unsigned long resume_freq;
    atomic_t suspend_count;
    struct devfreq_stats stats;
    struct srcu_notifier_head transition_notifier_list;
    struct thermal_cooling_device *cdev;
    struct notifier_block nb_min;
    struct notifier_block nb_max;
};

🧚 MEMBERS 🧚

• node — list node — contains the devices with devfreq that have been registered. 🧵
• lock — a mutex to protect accessing devfreq. 🔒
• dev — device registered by devfreq class. dev.parent is the device using devfreq. 📱
• profile — device-specific devfreq profile. 🧬
• governor — method how to choose frequency based on the usage. 🎛️
• opp_table — Reference to OPP table of dev.parent, if one exists. 📋
• nb — notifier block used to notify the devfreq object that it should reevaluate operable frequencies. Devfreq users may use devfreq.nb to the corresponding register notifier call chain. 🔔
• work — delayed work for load monitoring. ⏳
• freq_table — current frequency table used by the devfreq driver. 📊
• max_state — count of entry present in the frequency table. 🔢
• previous_freq — previously configured frequency value. 🕰️
• last_status — devfreq user device info, performance statistics. 📈
• data — devfreq driver pass to governors, governor should not change it. 🚫
• governor_data — private data for governors, devfreq core doesn't touch it. 🙈
• user_min_freq_req — PM QoS minimum frequency request from user (via sysfs). 🧊
• user_max_freq_req — PM QoS maximum frequency request from user (via sysfs). 🔥
• scaling_min_freq — Limit minimum frequency requested by OPP interface. ⬇️
• scaling_max_freq — Limit maximum frequency requested by OPP interface. ⬆️
• stop_polling — devfreq polling status of a device. 🛑
• suspend_freq — frequency of a device set during suspend phase. 😴
• resume_freq — frequency of a device set in resume phase. 🌅
• suspend_count — suspend requests counter for a device. 🧮
• stats — Statistics of devfreq device behavior. 📉
• transition_notifier_list — list head of DEVFREQ_TRANSITION_NOTIFIER notifier. 🚦
• cdev — Cooling device pointer if the devfreq has cooling property. ❄️
• nb_min — Notifier block for DEV_PM_QOS_MIN_FREQUENCY. 🧊
• nb_max — Notifier block for DEV_PM_QOS_MAX_FREQUENCY. 🔥

💫 DESCRIPTION 💫

This structure stores the devfreq information for a given device. 💾

okay so important, bestie: when a governor accesses entries in struct devfreq in its functions — except for the context of callbacks defined in struct devfreq_governor — the governor should protect its access with the struct mutex lock in struct devfreq. A governor may use this mutex to protect its own private data in void *data as well. 🔐

🔥 SEE ALSO 🔥

• Kernel file ./include/linux/devfreq.h — also peep struct devfreq_dev_status(9), struct devfreq_dev_profile(9), struct devfreq_stats(9), struct devfreq_simple_ondemand_data(9), struct devfreq_passive_data(9). 👀

xoxo bestie 💖 — this page comes from source ./include/linux, dated October 2026, and the version/manual title is struct devfreq(9). slay. 🎀