led_classdev_register_ext(9)

💡 led_classdev_register_ext(9) — or, how to birth a brand-new LED bestie ✨

okay so this page lives in the Kernel API Manual, and it's lowkey the origin story of every LED class device you've ever met. it's the _ext version, which means it takes init data and derives the name from it — main character energy from the very first line, periodt. 🎀

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🌸 SYNOPSIS

int led_classdev_register_ext (struct device *parent , struct
led_classdev *led_cdev , struct led_init_data *init_data );

three arguments, one int coming back at you. that's the whole vibe check. 🦋

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🫶 ARGUMENTS

• parent — the LED controller device that's actually driving this LED. like, the parent, the source of the power, the one who made it all possible 💖
• led_cdev — the led_classdev structure for this device. this is the actual baby being registered, bestie 🌸
• init_data — the LED class device initialization data. this is where the name comes from, so pay attention 👑

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✨ DESCRIPTION

so what does it do? it registers a new object of the LED class, with the name derived from init_data. that's it, that's the whole thing — but ngl that's a pretty iconic job. your brand new LED is officially on the roster 💅

fr fr, init_data is the plug here — no init data, no name. don't forget it. 🙈

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🔥 RETURN

• 0 on success 🎉 slay, you did it
• a negative error value on failure 💀 it's giving "not today"

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💜 SEE ALSO

okay this is the friend group, and honestly they're all iconic in their own way. all of these live in the kernel file ./include/linux/leds.h:

• struct led_lookup_data(9)
• led_classdev_register(9)
• led_blink_set(9)
• led_blink_set_nosleep(9)
• led_blink_set_oneshot(9)
• led_set_brightness(9)
• led_set_brightness_sync(9)
• led_mc_set_brightness(9)
• led_update_brightness(9)
• led_get_default_pattern(9)
• led_sysfs_disable(9)
• led_sysfs_enable(9)
• led_compose_name(9)
• led_get_color_name(9)
• led_sysfs_is_disabled(9)
• struct led_pattern(9)

go read them all, iykyk 👑🌈

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quick reminder bestie: the name comes from init_data, so if your LED ends up with a cursed name, that's where you look. not me, not the kernel, not the vibes. 🍓

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and that's the whole page, mwah 💋 this little gem ships from ./include/linux, dated October 2026, and it's page led_classdev_register_ext(9) of the Kernel API Manual — go register something iconic, bestie, you've got this 🧚⭐💖