STRUCT SCMI_EVENT_HANDLER(9)

💖 struct scmi_event_handler(9) 💖

okay so bestie, welcome to the Kernel API Manual — this is the page for struct scmi_event_handler, and it's literally the little bookkeeping babe that keeps track of event handler info. no cap, it's giving "backstage pass coordinator" energy. let's get into it 🎀

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✨ NAME ✨

struct scmi_event_handler — Event handler information 🫶

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🌸 SYNOPSIS 🌸

struct scmi_event_handler {
    u32 key;
    refcount_t users;
    struct scmi_registered_event    *r_evt;
    struct blocking_notifier_head   chain;
    struct hlist_node               hash;
    bool enabled;
 };

like, that's the whole vibe. six fields, all iconic, each one doing its little job 💅

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👑 Members 👑

key

The used hashkey 🔑

users

A reference count for number of active users for this handler — yes it's counting how many besties are currently using it 📈

r_evt

A reference to the associated registered event; when this is NULL this handler is pending, which means that identifies a set of callbacks intended to be attached to an event which is still not known nor registered by any protocol at that point in time 🌫️

ngl, NULL here = the handler is in its waiting-room era. it's got callbacks ready to go, but the event it's meant for isn't known or registered by any protocol yet. main character in limbo fr fr 😭

chain

The notification chain dedicated to this specific event tuple ⛓️

hash

The hlist_node used for collision handling 🧩

enabled

A boolean which records if event's generation has been already enabled for this handler as a whole ✅

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💜 Description 💜

So this structure collects all the information needed to process a received event identified by the tuple (proto_id, evt_id, src_id). those three lil ids? that's the whole identity, bestie 🌈

These descriptors are stored in a per-protocol registered_events_handlers table using as a key a value derived from that tuple. so basically: tuple goes in, key comes out, table lookup happens, slay 💫

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🦋 SEE ALSO 🦋

• The Kernel file ./drivers/firmware/arm_scmi/notify.c 🔥
• Theory of operation(9)
• struct scmi_notify_instance(9)
• struct events_queue(9)
• struct scmi_event_header(9)
• struct scmi_registered_events_desc(9)
• struct scmi_registered_event(9)
• scmi_lookup_and_call_event_chain(9)
• scmi_process_event_header(9)
• scmi_process_event_payload(9)
• scmi_events_dispatcher(9)
• scmi_notify(9)
• scmi_kfifo_free(9)
• scmi_initialize_events_queue(9)
• scmi_allocate_registered_events_desc(9)
• scmi_register_protocol_events(9)
• scmi_deregister_protocol_events(9)
• scmi_allocate_event_handler(9)
• scmi_free_event_handler(9)
• scmi_bind_event_handler(9)
• scmi_valid_pending_handler(9)
• scmi_register_event_handler(9)
• __scmi_event_handler_get_ops(9)
• scmi_get_active_handler(9)
• __scmi_enable_evt(9)
• scmi_put_handler_unlocked(9)
• scmi_event_handler_enable_events(9)
• scmi_notifier_register(9)
• scmi_notifier_unregister(9)
• scmi_devm_notifier_register(9)
• scmi_devm_notifier_unregister(9)
• scmi_protocols_late_init(9)
• scmi_notification_init(9)
• scmi_notification_quiesce(9)
• scmi_notification_exit(9)

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and that's the page!! tysm for reading, ily 🫶 this one lives under ./drivers/firmware/arm_scmi and it's dated October 2026 — go off, king 💅✨🌷