spi_nor_read_sfdp(9)

📦 version 7.3.1, in nixpkgs unstable

💅 spi_nor_read_sfdp(9) — bestie edition

okay so this is a page from the Kernel API Manual, and the function we're stanning today is spi_nor_read_sfdp(9). it's giving "let me just peek at the flash's little résumé" energy, and honestly? iconic.

✨ NAME ✨

spi_nor_read_sfdp — read Serial Flash Discoverable Parameters. literally the flash chip handing you its business card 🫶

🌸 SYNOPSIS 🌸

int spi_nor_read_sfdp (struct spi_nor *nor , u32 addr , size_t len ,
       void *buf );

🎀 ARGUMENTS 🎀

  • nor — pointer to a struct spi_nor. this is your main character, the flash device you're talking to 💖
  • addr — the offset in the SFDP area where you wanna start reading data from. like picking which page of the résumé to start on 📍
  • len — number of bytes to read. how much tea you're asking for ☕
  • buf — the buffer where the SFDP data get copied into. and heads up: it has to be dma-safe memory — do not skimp on this, it's not a vibe to ignore 🫠

🦋 DESCRIPTION 🦋

so here's the thing, bestie: no matter what the actual numbers of bytes for address and dummy cycles happen to be for (Fast) Read commands, the Read SFDP (5Ah) instruction is always followed by a 3-byte address and 8 dummy clock cycles. always always. no notes, no exceptions, no "but what if" — that's just how it is ✨

🔥 RETURN 🔥

0 on success, -errno otherwise. so like… hit me with that zero and we're golden, anything else and it's a whole mood 💀

👑 SEE ALSO 👑

Kernel file ./drivers/mtd/spi-nor/sfdp.c plus the whole friend group:

that's the whole page, bestie!! 🥳 this gem lives in <code>./drivers/mtd/spi-nor</code> and the version we were reading is dated <strong>October 2026</strong> — go forth and read those discoverable parameters 💜✨

📦 where this page comes from