xudc_ep0_in(9)

📦 version 7.3.1, in nixpkgs unstable

💅 xudc_ep0_in(9) — the Kernel API Manual page you didn't know you needed

okay so first things first, bestie: this is xudc_ep0_in(9) from the Kernel API Manual, section 9, and it's a tiny little page but like, it's doing something real. get comfy 🫶

✨ NAME ✨

xudc_ep0_in — literally processes the endpoint 0 IN token. that's it, that's the whole job. main character energy for one specific token, and honestly? respect. 👑

🌸 SYNOPSIS 🌸

void xudc_ep0_in (struct xusb_udc *udc );

returns nothing (void, so don't go looking for a return value, she gives you nothing back 💀), and it takes exactly one thing.

🎀 ARGUMENTS 🎀

  • udc — pointer to the usb device controller structure. yes, the structure. the one that holds the whole controller vibe together. you're passing her a pointer, not a copy, so be normal about it. 🦋

💖 SEE ALSO 💖

okay this is the part where the page goes absolutely feral and links to basically the entire Xilinx UDC universe. we're talking the whole friend group. and it all lives in the kernel file ./drivers/usb/gadget/udc/udc-xilinx.c — come through, source file. 🔥

the structs first, because we stan data shapes:

  • struct xusb_req(9)
  • struct xusb_ep(9)
  • struct xusb_udc(9)

then the register-poking girlies (there are BE versions, don't mix them up, that's a vibe check you do NOT want to fail 🙈):

DMA squad, moving your bytes around ✨:

FIFO and transaction crew:

halt / enable / disable / request management, the whole lifecycle honestly:

misc controller duties (frame counting, waking up, pulling up, init-ing, stopping activity, starting, stopping, clearing all the stalls):

control-transfer besties, aka the ep0 inner circle — look, xudc_ep0_out is literally right there, sibling behavior 😭:

interrupt + handler crew:

and finally the driver's actual entry/exit points, the beginning and the end of the story:

ok tiny warning-ish aside: this page is super short, so like, don't read it expecting lore. it does one thing (endpoint 0 IN token processing) and it does it. if you want the full picture, follow the SEE ALSO list, it's giving lore drop. 📚

and that's the page, bestie!! 💜 this lil icon came out of ./drivers/usb/gadget/udc (that's the source, mwah) and she's dated October 2026 — so if you're reading this in the future, hi, love you, drink water, and remember: xudc_ep0_in(9), Kernel API Manual, section 9. periodt. 🎀✨🌈

📦 where this page comes from