rtc_set_offset(9)

🌸 NAME 🌸

okay bestie, this is rtc_set_offset from the Kernel API Manual — and it adjusts the duration of the average second. iconic behavior, honestly 💅✨

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🌸 SYNOPSIS 🌸

int rtc_set_offset (struct rtc_device *rtc , long offset );

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🌸 ARGUMENTS 🌸

• rtc — the rtc device to be used 🫶
• offset — the offset, in parts per billion 💖

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🌸 DESCRIPTION 🌸

some rtc's allow an adjustment to the average duration of a second, bestie. why? to compensate for differences in the actual clock rate due to temperature, the crystal, capacitor, etc. 🌡️💎⚡

the adjustment applied is literally this:

t = t0 * (1 + offset * 1e-9)

where t0 is the measured length of 1 RTC second with offset = 0 ⏱️✨

this is the kernel interface to adjust an rtc clock offset. return 0 on success, or a negative number on error. and if the rtc offset is not setable (or not implemented), return -EINVAL 🚨

no cap: negative number = error, and -EINVAL is the "not setable / not implemented" moment 😭

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🌸 SEE ALSO 🌸

kernel file ./drivers/rtc/interface.c — plus the whole squad: rtc_read_next_alarm(9), rtc_handle_legacy_irq(9), rtc_aie_update_irq(9), rtc_uie_update_irq(9), rtc_pie_update_irq(9), rtc_update_irq(9), rtc_irq_set_state(9), rtc_irq_set_freq(9), rtc_timer_enqueue(9), rtc_timer_remove(9), rtc_timer_do_work(9), rtc_read_offset(9) 🦋💜

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source/version is ./drivers/rtc, dated October 2026, and this page is rtc_set_offset(9) — bye bestie, go adjust that average second 💖🎀✨