devm_spi_ne...llary_device(9)

💖 NAME 💖

devm_spi_new_ancillary_device — register a managed ancillary SPI device, bestie ✨

okay so real quick, this is the kernel API manual for it, and yes we're gonna get through it together 🫶

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🌸 SYNOPSIS 🌸

struct spi_device * devm_spi_new_ancillary_device (struct spi_device
*spi , u8 chip_select );

like, it takes two things and hands you back a struct spi_device *, periodt 💅

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🎀 ARGUMENTS 🎀

• spi — pointer to the main SPI device, aka the one that's registering the ancillary device 👑 it's giving parent energy
• chip_select — a u8, the Chip Select of the ancillary device. yes it's a u8. no we will not be questioning it 🍓

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✨ DESCRIPTION ✨

So what does it actually do? It registers an ancillary SPI device — and the example in the docs is honestly so good: some chips have a chip-select for normal device usage, and another one for setup/firmware upload. like, two CS pins, one chip, main character energy fr fr 🔥

This is the managed version of spi_new_ancillary_device — that's what the devm_ prefix is telling you, iykyk. The ancillary device gets unregistered automatically when the parent SPI device is unregistered. no manual cleanup, no leaked devices, we love a self-cleaning situation 🧚💜

⚠️ lowkey important: this may only be called from the main SPI device's probe routine. that's the rule. don't be out here calling it from just anywhere 😭

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💀 RETURN 💀

• Pointer to the new ancillary device on success 🎉
• ERR_PTR on failure 🙈 (so yeah, check it — IS_ERR/PTR_ERR are your besties here, that's just how ERR_PTR works)

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🌈 SEE ALSO 🌈

Kernel file ./drivers/spi/spi.c — and here's the full squad, every single one, no cap:

__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), 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... that's the whole friend group, go say hi 💖

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✨ and that's the page!! ✨ sourced from ./drivers/spi, dated October 2026, and it's the devm_spi_ne...llary_device(9) page — yes the title is truncated in the header, that's just how it's printed, don't @ me 💅🎀 see u in the next manpage bestie 🦋