CP2112(4)

📦 version 15.1, in freebsd 14.5, freebsd 15.1, nixpkgs unstable

💜 CP2112(4) — cp2112

okay so welcome to the Kernel Interfaces Manual, section 4, bestie — this is where we talk about cp2112, which is literally the driver for a USB GPIO and I2C peripheral device. sit down, grab a strawberry 🍓, we're gonna get into it.

✨ NAME ✨

cp2112 — driver for a USB GPIO and I2C peripheral device 👑

🎀 SYNOPSIS 🎀

so if you wanna compile this driver into the kernel (yes, fully baked in, main character energy), you drop these lines into your kernel configuration file:

device cp2112
device usb
device gpio
device iicbus

or — and this is the lowkey easier path — you can load the driver as a module at boot time instead, by putting this one line in loader.conf(5):

cp2112_load="YES"

both options are valid, pick your fighter 💅

🌸 DESCRIPTION 🌸

the cp2112 driver provides support for the Silicon Labs CP2112 device, and honestly? it's giving "small but mighty." this thing has 8 general purpose I/O pins plus an I2C controller that supports a subset of the I2C protocol. no cap, that's the whole vibe.

all pins support both input and output modes — versatile icon behavior 🦋. and when a pin is doing output, you can configure it for either open-drain or push-pull operation, so you've got options.

now, the special ones: pins 0, 1 and 7 support special functions — that's I2C transmit indication, I2C receive indication and clock output respectively. sounds amazing, right? well... at the moment the cp2112 driver does not provide a way to enable and configure those special functions. so they're just kinda sitting there being iconic and unusable 😭🙈.

the I2C controller itself is where the numbers get spicy 🔥 — here's the tea:

  • it supports read transactions with up to 512 bytes of data
  • it supports write transactions with up to 61 bytes of data
  • it supports a write followed by the repeated start followed by a read transaction, where the write can be up to 16 bytes and the read can be up to 512 bytes
  • zero length transfers are not supported — nope, not a thing, don't even try 💀

and finally, the driver creates a gpio(4) and iicbus(4) child buses to expose the respective functions. so like, it's not doing everything itself — it's delegating, as a queen should 👑.

🌈 SEE ALSO 🌈

go read those next, iykyk 📚✨

⭐ HISTORY ⭐

the cp2112 driver and this manual page were written by Andriy Gapon <avg@FreeBSD.org> — we stan a writer who ships both the code and the docs 🫶 periodt.

and that's the whole page, bestie!! this one comes to you from the Debian flavor of things, dated August 12, 2020, living in CP2112(4) — mwah 💖🎀🧚

📦 where this page comes from