sdio_writel(9)

💅 sdio_writel — kernel API manual, but make it make sense

okay so bestie, welcome to sdio_writel(9) from the Kernel API Manual — yes it's a real manpage, yes it's about the kernel, and yes i'm gonna walk you through it like we're on facetime 🫶

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✨ NAME ✨

sdio_writel — writes a 32 bit integer into a SDIO function. that's it. that's the whole vibe. a little 32-bit number goes in, the SDIO function eats it 💅

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🌸 SYNOPSIS 🌸

void sdio_writel (struct sdio_func *func , u32 b , unsigned int addr ,
       int *err_ret );

look at her. iconic signature. no return value, she just does the thing ✨

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🎀 ARGUMENTS 🎀

• func — the SDIO function you're accessing, fr fr. this is your main character.
• b — the integer you're writing. the payload. the moment. the 32-bit snack 🍓
• addr — the address you're writing to. like a lil mailbox for your integer.
• err_ret — optional status value from the transfer. optional!! so if you don't care about the status you can just… not. but she's there if you need her 🦋

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💖 DESCRIPTION 💖

so basically: this writes a 32 bit integer into the address space of a given SDIO function. yep. that's the whole plot.

and err_ret will contain the status of the actual transfer — so if you passed it in, it gets the receipts of what actually went down 📬

lowkey the move is: pass err_ret if you wanna know how it went. skip it if you're built different (but like… don't be messy about it, bestie) 🙈

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🔥 SEE ALSO 🔥

• Kernel file ./drivers/mmc/core/sdio_io.c — that's where she lives, go say hi 👑
• sdio_claim_host(9)
• sdio_release_host(9)
• sdio_enable_func(9)
• sdio_disable_func(9)
• sdio_set_block_size(9)
• sdio_align_size(9)
• sdio_readb(9)
• sdio_writeb(9)
• sdio_writeb_readb(9)
• sdio_memcpy_fromio(9)
• sdio_memcpy_toio(9)
• sdio_readsb(9)
• sdio_writesb(9)
• sdio_readw(9)
• sdio_writew(9)
• sdio_readl(9)
• sdio_f0_readb(9)
• sdio_f0_writeb(9)
• sdio_get_host_pm_caps(9)
• sdio_set_host_pm_flags(9)
• sdio_retune_crc_disable(9)
• sdio_retune_crc_enable(9)
• sdio_retune_hold_now(9)
• sdio_retune_release(9)

like, the whole friend group showed up. every single one. we love a supportive ensemble cast 💜✨

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and that's the page!! brought to you by ./drivers/mmc/core in October 2026 — mwah, sending you the most immaculate kernel vibes 🌈💖 go write that 32 bit integer bestie, iykyk 🧚