mips_cdmm_early_probe(9)

💅 mips_cdmm_early_probe 💅

okay so real talk bestie, this is mips_cdmm_early_probe(9) from the Kernel API Manual — and yes it's a kernel thing, but it's actually kind of a slay?? it's the "sneak a peek at the hardware before literally anything else is ready" function. iconic behaviour. let's get into it 🫶

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✨ NAME ✨

mips_cdmm_early_probe — the bare-minimum little probe that goes looking for one specific device on CDMM 🎀

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🌸 SYNOPSIS 🌸

void __iomem * mips_cdmm_early_probe (unsigned int dev_type );

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🦋 ARGUMENTS 🦋

• dev_type — the CDMM type code you're hunting for. that's it. that's the whole assignment 🔍

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💖 DESCRIPTION 💖

so basically you minimally configure the in-CPU Common Device Memory Map (CDMM) — like, the lightest possible setup, no overachieving — and then you go look for one specific device. that's the vibe. 💅

and why would you even do this? because it can be used to find a device very early in boot — for example to configure an early FDC console device. yeah. before everything. main character energy from the jump 🔥

⚠️ okay important one, bestie: the caller must prevent migration to another CPU. how? either by disabling pre-emption, or by running from a pinned kernel thread. no cap, this part matters — do not skip it 😭

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⭐ RETURN ⭐

you get back an MMIO pointer to device memory. cute! 🎀

the caller can read the ACSR register to find more information about the device — stuff like the version number or the number of blocks 👑

and listen: it may return IOMEM_ERR_PTR(-errno) in case of error, so check with IS_ERR. literally always check. don't be out here trusting pointers blindly 🙈

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🧚 SEE ALSO 🧚

• Kernel file ./drivers/bus/mips_cdmm.c — struct mips_cdmm_work_dev(9)
• mips_cdmm_void_work(9)
• mips_cdmm_int_work(9)
• BUILD_PERCPU_HELPER(9)
• mips_cdmm_driver_register(9)
• mips_cdmm_driver_unregister(9)
• struct mips_cdmm_bus(9)
• mips_cdmm_get_bus(9)
• mips_cdmm_cur_base(9)
• mips_cdmm_phys_base(9)
• mips_cdmm_setup(9)
• mips_cdmm_release(9)
• mips_cdmm_bus_discover(9)
• BUILD_PERDEV_HELPER(9)
• mips_cdmm_cpu_down_prep(9)
• mips_cdmm_cpu_online(9)
• mips_cdmm_init(9)

like the whole friend group, fr fr 💜

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and that's the page!! brought to you straight out of ./drivers/bus, dated October 2026 — so go forth, probe responsibly, and remember: check with IS_ERR or it's on you 😘💖✨