STRUCT ACPM_CHAN(9)

🌟 NAME 🌟

okay bestie, this is the struct acpm_chan(9) page from the Kernel API Manual, and it's all about struct acpm_chan — the driver internal representation of a channel. That's the whole assignment, no cap. 💅✨

✨ SYNOPSIS ✨

okay so the shape is literally this, and yes the spacing and semicolons are doing their thing:

       struct acpm_chan {
           struct mbox_client cl;
           struct mbox_chan *chan;
           struct acpm_info *acpm;
           struct acpm_queue tx;
           struct acpm_queue rx;
           struct mutex tx_lock;
           struct mutex rx_lock;
           unsigned int qlen;
           unsigned int mlen;
           u8 seqnum;
           u8 id;
           bool poll_completion;
           unsigned long bitmap_seqnum[BITS_TO_LONGS( ACPM_SEQNUM_MAX - 1)];
           struct acpm_rx_data rx_data[ACPM_SEQNUM_MAX];
        };

🦋 Members 🦋

• cl — mailbox client. The mailbox bestie, obviously. 💌
• chan — mailbox channel. The actual channel, slay. 📬
• acpm — pointer to driver private data. It's giving "my private data, not yours" energy. 🙈
• tx — TX queue. The enqueue is done by the host. The way this queue works is a whole little system:
  • front index is written by the host.
  • rear index is written by the firmware.
• rx — RX queue. The enqueue is done by the firmware. Same queue energy, opposite directions:
  • front index is written by the firmware.
  • rear index is written by the host.
• tx_lock — protects TX queue. Lock it up, bestie. 🔒
• rx_lock — protects RX queue. Another lock, another slay. 🔐
• qlen — queue length. Applies to both TX/RX queues. Both of them, periodt. 📏
• mlen — message length. Applies to both TX/RX queues. Same energy. 📐
• seqnum — sequence number of the last message enqueued on TX queue. Last one in, tracked. 🔢
• id — channel ID. Gotta have an ID, obviously. 🆔
• poll_completion — indicates if the transfer needs to be polled for completion or interrupt mode is used. So: polled completion or interrupt mode, those are the options. ⏳
• bitmap_seqnum — bitmap that tracks the messages on the TX/RX queues. Tracking them messages, very organized. 🗂️
• rx_data — internal buffer used to drain the RX queue. Draining the queue, literally. 🚰

💖 SEE ALSO 💖

Kernel file: ./drivers/firmware/samsung/exynos-acpm.c — and here's the whole friend group, bestie:

• struct acpm_shmem(9)
• struct acpm_chan_shmem(9)
• struct acpm_queue(9)
• struct acpm_rx_data(9)
• struct acpm_info(9)
• struct acpm_match_data(9)
• acpm_get_saved_rx(9)
• acpm_get_rx(9)
• acpm_dequeue_by_polling(9)
• acpm_wait_for_queue_slots(9)
• acpm_prepare_xfer(9)
• acpm_wait_for_message_response(9)
• acpm_do_xfer(9)
• acpm_set_xfer(9)
• acpm_chan_shmem_get_params(9)
• acpm_achan_alloc_cmds(9)
• acpm_free_mbox_chans(9)
• acpm_channels_init(9)
• acpm_handle_put(9)
• devm_acpm_release(9)
• acpm_get_by_node(9)
• devm_acpm_get_by_node(9)
• devm_acpm_get_by_phandle(9)

mwah 💋 — source/version: ./drivers/firmware/samsung; date: October 2026. stay iconic, bestie 🫶✨