to_sas_gpio_gp_bit(9)

✨ to_sas_gpio_gp_bit(9) ✨

okay so this is a page from the Kernel API Manual bestie, and the function we're obsessing over is to_sas_gpio_gp_bit — say that five times fast, i literally can't 💀

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🎀 NAME 🎀

to_sas_gpio_gp_bit — given the gpio frame data, find the byte/bit position of 'od'. that's it, that's the whole gig 💅

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🌸 SYNOPSIS 🌸

u8 * to_sas_gpio_gp_bit (unsigned int od , u8 *data , u8 index , u8 count , u8 *bit );

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💖 ARGUMENTS 💖

• od — the od bit you're trying to find, like a little scavenger hunt 🔍
• data — the incoming bitstream (straight from the frame, no filter, no edits ✨)
• index — the requested data register index (also from the frame, she comes with receipts 🧾)
• count — the total number of registers in the bitstream (from the frame, keep counting girly 🎀)
• bit — where the 'od' bit actually landed inside the returned byte 📍

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🦋 DESCRIPTION 🦋

returns NULL if 'od' is not in 'data' — like, not found, not invited to the party, don't @ her 😭

now for the lore. straight from SFF-8485 v0.7, and i'm quoting so you know it's real:

"In GPIO_TX[1], bit 0 of byte 3 contains the first bit (i.e., OD0.0) and bit 7 of byte 0 contains the 32nd bit (i.e., OD10.1).

In GPIO_TX[2], bit 0 of byte 3 contains the 33rd bit (i.e., OD10.2) and bit 7 of byte 0 contains the 64th bit (i.e., OD21.0)."

the general-purpose (raw-bitstream) RX registers have the exact same layout, except 'od' gets a glow-up and is renamed 'id' for 'input data'. same vibe, different name, main character energy 👑

and SFF-8489 defines how the LEDs behave in response to the 'od' values. so yes, the LEDs are involved. slay ✨

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🌈 SEE ALSO 🌈

• Kernel file ./drivers/scsi/libsas/sas_host_smp.c — go read it, iykyk 💜

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and that's the whole page bestie, no notes 🫶 this one's from ./drivers/scsi/libsas, dated October 2026 — catch you on the next man page, mwah 💋🎀