STRUCT XHCI_OP_REGS(9)

🎀 NAME 🎀

okay so bestie, welcome to the Kernel API Manual ✨ — this one's struct xhci_op_regs, aka the xHCI Host Controller Operational Registers 💅. yes it's a struct, yes it's in a kernel, yes you're gonna slay it.

🌸 SYNOPSIS 🌸

struct xhci_op_regs {
    __le32 command;
    __le32 status;
    __le32 page_size;
    __le32 reserved1;
    __le32 reserved2;
    __le32 dev_notification;
    __le64 cmd_ring;
    __le32 reserved3[4];
    __le64 dcbaa_ptr;
    __le32 config_reg;
    __le32 reserved4[241];
    struct xhci_port_regs port_regs[];
};

like, look at her. main character struct energy fr fr 👑 — she's got the little registers up top, a couple of big 64-bit pointers in the middle, and a whole wall of reserved space because sometimes you just need room 🫶

🦋 Members 🦋

• command — this is USBCMD, the xHC command register 💫 the "do the thing" button, basically.
• status — this one's USBSTS, the xHC status register 👀 the "what's the tea, is it working" register.
• page_size — tells you what page size the host controller supports ✨ and here's the deets: if bit n is set, the HC supports a page size of 2^(n+12), all the way up to a 128MB page size 🫧 and the minimum page size is 4K. no cap, that's the floor.
• cmd_ring — CRP, the 64-bit Command Ring Pointer 🌈
• dcbaa_ptr — DCBAAP, the 64-bit Device Context Base Address Array Pointer 💜 (yes that's a lot of words, yes it's one pointer, we move)
• config_reg — CONFIG, the Configure Register ⭐
• port_regs — the Port Register Sets 💅 and there's one for each port, from 1 to MaxPorts, where MaxPorts is defined by HCSPARAMS1. iconic array energy.

not me noticing the struct also carries reserved1, reserved2, dev_notification, reserved3[4] and reserved4[241] — the page doesn't give them their own little blurbs, so I'm not gonna invent any 🙈 they're just sitting there being reserved, and we respect their privacy.

⭐ SEE ALSO ⭐

the whole friend group, in the kernel file ./drivers/usb/host/xhci.h 💖:

• struct xhci_cap_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)

okay that's the whole page, you ate that 🍓 mwah 💋

sign-off time cuties: this one lives in ./drivers/usb/host, dated October 2026, and it's struct xhci_op_regs(9) — go be the main character of your own register set 🧚💜