__spi_alloc_controller(9)

💖 __spi_alloc_controller(9) 💖

okay so bestie, we're in the Kernel API Manual and this is the page for __spi_alloc_controller(9) — the little function that gets you an SPI host or target controller. yes it's a double-underscore name, no I don't know why, we don't ask questions, we just read the docs. 🎀

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✨ NAME ✨

__spi_alloc_controller — allocate an SPI host or target controller 🌸

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🦋 SYNOPSIS 🦋

struct spi_controller * __spi_alloc_controller (struct device *dev ,
       unsigned int size , bool target );

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💅 ARGUMENTS 💅

• dev — the controller, possibly using the platform_bus. that's your device bestie 🫶
• size — how much zeroed driver-private data to allocate. the pointer to this memory lives in the driver_data field of the returned device, and you get at it with spi_controller_get_devdata. the memory is cacheline aligned. and listen — if you're a driver granting DMA access to portions of your private data, you gotta round up the size using ALIGN(size, dma_get_cache_alignment). do not skip that step, it's giving important ✨
• target — flag saying whether to allocate an SPI host controller (false) or an SPI target controller (true). pick your fighter 💀

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😴 CONTEXT 😴

can sleep. like, it's allowed to sleep. nap-friendly function, we love to see it 🛌💤

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👑 DESCRIPTION 👑

k so this call is only used by SPI controller drivers — the ones that are literally the only ones directly touching chip registers. it's how they allocate an spi_controller structure, before they call spi_register_controller. main character energy but in a "you had to be there" way 💫

this must be called from context that can sleep. no cap. 🔥

the caller is responsible for:

• assigning the bus number
• initializing the controller's methods

…before calling spi_register_controller. and also for calling spi_controller_put to prevent a memory leak when you're done with the controller. yes, you. memory leaks are not cute, bestie 😭🙈

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🍓 RETURN 🍓

the SPI controller structure on success — else NULL. that's it. that's the whole vibe check 🧚

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🌈 SEE ALSO 🌈

the Kernel file ./drivers/spi/spi.c, plus literally this whole friend group:

• __spi_register_driver(9)
• spi_alloc_device(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)
• __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)

iykyk 💜

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anyway that's the page!! sourced from ./drivers/spi, dated October 2026, filed under __spi_alloc_controller(9) — love that for us, mwah, go allocate responsibly 🎀💖✨