STRUCT XHCI_CAP_REGS(9)

💅 struct xhci_cap_regs — NAME

okay bestie, welcome to the Kernel API Manual ✨ this page is all about struct xhci_cap_regs — the xHCI Host Controller Capability Registers. yes, the capability ones. the first block of regs your host controller hits you with, and it's giving main character energy fr fr 👑

🎀 SYNOPSIS 🎀

like, here's literally the whole struct, character for character, no cap:

struct xhci_cap_regs {
    __le32 hc_capbase;
    __le32 hcs_params1;
    __le32 hcs_params2;
    __le32 hcs_params3;
    __le32 hcc_params;
    __le32 db_off;
    __le32 run_regs_off;
    __le32 hcc_params2;
 };

look at her. eight __le32 fields in a little row. obsessed 🫶

🌸 Members 🌸

here's the member-by-member vibe check, one bullet each, nothing skipped:

• hc_capbase — the length of the capabilities register plus the HC version number. two facts in one reg, multitasking icon 💅
• hcs_params1 — HCSPARAMS1 — Structural Parameters 1
• hcs_params2 — HCSPARAMS2 — Structural Parameters 2
• hcs_params3 — HCSPARAMS3 — Structural Parameters 3
• hcc_params — HCCPARAMS — Capability Parameters
• db_off — DBOFF — Doorbell array offset. yes, doorbell 🔔
• run_regs_off — RTSOFF — Runtime register space offset
• hcc_params2 — HCCPARAMS2 Capability Parameters 2 — and bestie, note this one is xhci 1.1 only. don't come for her if you're on an older spec 💀

🦋 SEE ALSO 🦋

siblings!! the whole family lives in the kernel file ./drivers/usb/host/xhci.h, and honestly you should go say hi to all of them:

• struct xhci_op_regs(9)
• struct xhci_intr_reg(9)
• struct xhci_run_regs(9)
• struct xhci_container_ctx(9)
• struct xhci_slot_ctx(9)
• struct xhci_ep_ctx(9)
• struct xhci_device_context_array(9)

ngl this whole page lives under ./drivers/usb/host and it's dated October 2026 — so yeah, future vibes only 🌈 go read the source, it ate 🔥

that's the whole thing, bestie — go forth and read them capability regs 💖🧚‍♀️