STRUCT HID_LL_DRIVER(9)

🌟 struct hid_ll_driver(9) 🌟

okay bestie, welcome to the Kernel API Manual, section 9, main character energy only ✨. This page is about struct hid_ll_driver — literally the low level driver callbacks, no cap. If you're working on the low-level side of HID, this struct is basically the group chat of callbacks, and every member has a job. iykyk 💅

🌸 NAME 🌸

struct hid_ll_driver — low level driver callbacks. That's the whole name, bestie: the low-level callback squad for HID drivers. Slay. 💖

✨ SYNOPSIS ✨

lowkey here's the exact shape of the struct, fr fr — don't let the function-pointer syntax jump-scare you 🫶:

       struct hid_ll_driver {
           int (*start)(struct hid_device *hdev);
           void (*stop)(struct hid_device *hdev);
           int (*open)(struct hid_device *hdev);
           void (*close)(struct hid_device *hdev);
           int (*power)(struct hid_device *hdev, int level);
           int (*parse)(struct hid_device *hdev);
           void (*request)(struct hid_device *hdev, struct hid_report *report,
       int reqtype);
           int (*wait)(struct hid_device *hdev);
           int (*raw_request) (struct hid_device *hdev, unsigned char
       reportnum, __u8 *buf, size_t len, unsigned char rtype, int reqtype);
           int (*output_report) (struct hid_device *hdev, __u8 *buf, size_t
       len);
           int (*idle)(struct hid_device *hdev, int report, int idle, int
       reqtype);
           bool (*may_wakeup)(struct hid_device *hdev);
           unsigned int max_buffer_size;
        };

💅 Members 💅

here's the roster, one by one — no member left behind 🫶:

• start — called on probe to start the device. 💖
• stop — called on remove. 🫶
• open — called by input layer on open. ✨
• close — called by input layer on close. 🎀
• power — request underlying hardware to enter requested power mode. 🔋
• parse — this method is called only once to parse the device data, shouldn't allocate anything to not leak memory. ⚠️ seriously, bestie: don't leak memory — that's not the vibe.
• request — send report request to device (e.g. feature report). 📨
• wait — wait for buffered io to complete (send/recv reports). ⏳
• raw_request — send raw report request to device (e.g. feature report). 🧚
• output_report — send output report to device. 📤
• idle — send idle request to device. 💤
• may_wakeup — return if device may act as a wakeup source during system-suspend. 🌙
• max_buffer_size — over-ride maximum data buffer size (default: HID_MAX_BUFFER_SIZE). 📦

🔗 SEE ALSO 🔗

vibe check these next, bestie — the whole HID friend group is here 😭:

• Kernel file ./include/linux/hid.h — home base 🏠
• HID quirks(9)
• struct hid_battery(9)
• struct hid_driver(9)
• module_hid_driver(9)
• hid_device_io_start(9)
• hid_device_io_stop(9)
• hid_map_usage(9)
• hid_map_usage_clear(9)
• hid_parse(9)
• hid_hw_power(9)
• hid_hw_idle(9)
• hid_hw_may_wakeup(9)
• hid_hw_wait(9)
• hid_report_len(9)

mwah 💋 source/version: ./include/linux; date: October 2026. That's the footer energy, bestie — now go make those callbacks iconic. 🫶✨💜