STRUCT TOUCHPAD_INFO_PROTOCOL(9)

💅 struct touchpad_info_protocol(9) — the kernel API manual, bestie edition

okay so welcome to section 9 of the Kernel API Manual, and today's main character is struct touchpad_info_protocol 🎀 this is literally the touchpad info response — like, the reply you get back when you ask a touchpad "hey bestie who are you". and it comes with receipts: message.type = 0x1020 and message.length = 0x006e. no cap, those exact numbers, memorize them 💅

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✨ SYNOPSIS ✨

here's the whole glow-up, verbatim, don't @ me:

struct touchpad_info_protocol {
    u8 unknown1[105];
    u8 model_flags;
    u8 model_no;
    u8 unknown2[3];
    __le16 crc16;
};

it's giving "mostly vibes, a little data" and honestly? iconic 🦋

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🌸 MEMBERS 🌸

• unknown1 — unknown 🙈 yeah that's it. that's the whole description. 105 bytes of beautiful mystery, we simply don't know, and that's okay.
• model_flags — the flags, which vary by model number, but whose significance is otherwise unknown 😭 so like, they exist, they do something, but the meaning is a mystery bestie. we love an enigmatic king.
• model_no — the touchpad model number 👑 this one actually tells you something, slay.
• unknown2 — unknown again 💀 three more bytes of "we don't know her". not me pointing at unlabeled bytes like "she's mysterious".
• crc16 — the crc over the whole message struct, and by whole we mean message header + this struct, minus this crc16 field itself. so it checks everything except itself, which is lowkey the most relatable thing in this entire struct. check your friends, not yourself ✨

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🦋 SEE ALSO 🦋

go read these next, fr fr, they're all in the Kernel file ./drivers/input/keyboard/applespi.c:

• struct keyboard_protocol(9)
• struct tp_finger(9)
• struct touchpad_protocol(9)
• struct command_protocol_tp_info(9)
• struct command_protocol_mt_init(9)
• struct command_protocol_capsl(9)
• struct command_protocol_bl(9)
• struct message(9)
• struct spi_packet(9)

a whole friend group honestly, they all hang out together 🌈

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ngl the theme here is "we documented the layout and left the semantics as an exercise for the reader" — that's not a bug, that's just what the original says, and we respect it 🫶

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okay that's the page!! 💖 brought to you from ./drivers/input/keyboard, dated October 2026, and yes the header and footer both still say struct touc...nfo_protocol(9) because truncation is camp actually ✨ bye bestie, go read your structs 🎀