spi_alloc_device(9)

💅 spi_alloc_device — the Kernel API Manual page, bestie edition ✨

okay so real talk, this is a page from the Kernel API Manual, and it's about spi_alloc_device — yes that's the whole title, we're not doing a subtitle, the manual name is literally just Kernel API Manual. Sit down, hydrate, and let's get into it 🫶

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🌸 NAME 🌸

spi_alloc_device — allocate a new SPI device, no cap 🎀

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✨ SYNOPSIS ✨

struct spi_device * spi_alloc_device (struct spi_controller *ctlr );

look at her go. one function, one pointer in, one pointer out 💅

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🦋 ARGUMENTS 🦋

• ctlr — the controller that this device is connected to. like, the whole vibe is which controller, that's the info you're giving it 🌈

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🌸 CONTEXT 🌸

can sleep 😴 — okay so this one is allowed to nap. she's not in a hurry. plan accordingly, don't call her from somewhere you can't sleep, iykyk.

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👑 DESCRIPTION 👑

so here's the thing — this function lets a driver allocate and initialize a spi_device without registering it immediately. iconique. it's giving "buy the outfit now, wear it later" 🎀

that delay is the whole point: it means a driver can directly fill that spi_device in with device parameters before calling spi_add_device on it. get her dressed first, then send her out 💅

now, the caller is responsible — and i mean responsible — for calling spi_add_device on the returned spi_device structure so it actually gets added to the SPI controller. no ghost devices, bestie 👻

but what if you changed your mind and need to discard that spi_device without adding it? totally valid, we support the decision. in that case you call spi_dev_put on it. that's the clean-up, don't skip the clean-up, the kernel will notice 🫶

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⭐ RETURN ⭐

a pointer to the new device, or NULL. so like... check it. seriously. NULL is a real possible outcome here, fr fr 🔥

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💜 SEE ALSO 💜

this list is long and honestly she ate, so we're listing every single one of them, no skips 🧚

oh and before the function refs — this all lives in the kernel file ./drivers/spi/spi.c 🍓

• __spi_register_driver(9)
• spi_add_device(9)
• spi_new_device(9)
• spi_unregister_device(9)
• spi_register_board_info(9)
• spi_res_alloc(9)
• spi_res_free(9)
• spi_res_add(9)
• spi_res_release(9)
• spi_finalize_current_transfer(9)
• __spi_pump_messages(9)
• spi_pump_messages(9)
• spi_take_timestamp_pre(9)
• spi_take_timestamp_post(9)
• spi_set_thread_rt(9)
• spi_get_next_queued_message(9)
• spi_finalize_current_message(9)
• spi_queued_transfer(9)
• spi_flush_queue(9)
• of_register_spi_devices(9)
• spi_new_ancillary_device(9)
• devm_spi_new_ancillary_device(9)
• acpi_spi_count_resources(9)
• acpi_spi_device_alloc(9)
• spi_target_abort(9)
• __spi_alloc_controller(9)
• __devm_spi_alloc_controller(9)
• spi_get_gpio_descs(9)
• spi_register_controller(9)
• devm_spi_register_controller(9)
• spi_unregister_controller(9)
• spi_replace_transfers(9)
• spi_split_transfers_maxsize(9)
• spi_split_transfers_maxwords(9)
• spi_set_cs_timing(9)
• spi_setup(9)
• spi_optimize_message(9)
• spi_unoptimize_message(9)
• devm_spi_optimize_message(9)
• spi_async(9)
• spi_sync(9)
• spi_sync_locked(9)
• spi_bus_lock(9)
• spi_bus_unlock(9)
• spi_write_then_read(9)

like. forty-five of them. she's thorough and we respect it 👑

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quick vibe check before you close the tab: if you got a device back and you're not adding it, spi_dev_put it. that's it. that's the PSA 💖

and that's the page!! this one came out of ./drivers/spi and it's dated October 2026 — shoutout to the section and the date, they're doing great, periodt 🌟💅