STRUCT CDNS2_DEVICE(9)

Hi bestie 💖 welcome to struct cdns2_device(9) from the Kernel API Manual. We're about to vibe-check a USB device struct together, and no cap, every member is getting its moment.

✨ NAME ✨

struct cdns2_device — literally the struct that represents a USB device. Main character energy fr fr. 🎀

🌸 SYNOPSIS 🌸

struct cdns2_device {
    struct device *dev;
    struct usb_gadget gadget;
    struct usb_gadget_driver *gadget_driver;
    spinlock_t lock;
    int irq;
    void __iomem *regs;
    struct cdns2_usb_regs __iomem *usb_regs;
    struct cdns2_ep0_regs __iomem *ep0_regs;
    struct cdns2_epx_regs __iomem *epx_regs;
    struct cdns2_interrupt_regs __iomem *interrupt_regs;
    struct cdns2_adma_regs __iomem *adma_regs;
    struct dma_pool *eps_dma_pool;
    struct usb_ctrlrequest setup;
    struct cdns2_request ep0_preq;
    u8 ep0_stage;
    void *zlp_buf;
    u8 dev_address;
    struct cdns2_endpoint eps[CDNS2_ENDPOINTS_NUM];
    u32 selected_ep;
    bool is_selfpowered;
    bool may_wakeup;
    bool status_completion_no_call;
    bool in_lpm;
    struct work_struct pending_status_wq;
    struct usb_request *pending_status_request;
    u32 eps_supported;
    u8 burst_opt[MAX_ISO_SIZE + 1];
    u16 onchip_tx_buf;
    u16 onchip_rx_buf;
};

Like, that's the whole squad right there. Obsessed with how tidy it is. 🫶

💅 Members 💅

• dev — pointer to the device structure associated with this controller. The home base, basically.
• gadget — device-side representation of the peripheral controller. Slay.
• gadget_driver — pointer to the gadget driver. The driver bestie in question.
• lock — for synchronizing. Gotta keep things from getting chaotic.
• irq — interrupt line number. The interrupt's little address, iykyk.
• regs — base address for registers.
• usb_regs — base address for common USB registers.
• ep0_regs — base address for endpoint 0 related registers.
• epx_regs — base address for all non-control endpoint registers.
• interrupt_regs — base address for interrupt handling related registers.
• adma_regs — base address for ADMA registers.
• eps_dma_pool — endpoint Transfer Ring pool. Cute little pool for the eps.
• setup — used while processing usb control requests. Very on-the-job.
• ep0_preq — private request used while handling EP0. Private means private, bestie.
• ep0_stage — ep0 stage during enumeration process. The lore of the enumeration era.
• zlp_buf — zlp buffer. Short, sweet, iconic.
• dev_address — device address assigned by host. The host said "this is your address now" and that's periodt.
• eps — array of objects describing endpoints. The whole endpoint ensemble.
• selected_ep — actually selected endpoint. It's used only to improve performance by limiting access to dma_ep_sel register. Highkey a performance flex.
• is_selfpowered — device is self powered. Independent queen behavior.
• may_wakeup — allows device to remote wakeup the host. Consent to wake the host: granted.
• status_completion_no_call — indicate that driver is waiting for status stage completion. It's used in deferred SET_CONFIGURATION request. The waiting-for-you energy is real.
• in_lpm — indicate the controller is in low power mode. Resting, but make it low power.
• pending_status_wq — workqueue handling status stage for deferred requests. Handling the to-do list, no cap.
• pending_status_request — request for which status stage was deferred. The request in the waiting room.
• eps_supported — endpoints supported by controller in form: bit: 0 - ep0, 1 - epOut1, 2 - epIn1, 3 - epOut2 ... A whole bit-map situation. 💀
• burst_opt — array with the best burst size value for different TRB size. Best burst size behavior only.
• onchip_tx_buf — size of transmit on-chip buffer in KB. TX buffer, but make it on-chip.
• onchip_rx_buf — size of receive on-chip buffer in KB. And the RX twin. Matching set 🎀

🦋 SEE ALSO 🦋

Kernel file ./drivers/usb/gadget/udc/cdns2/cdns2-gadget.h — and the whole friend group is here too: struct cdns2_ep0_regs(9), struct cdns2_epx_base(9), struct cdns2_epx_regs(9), struct cdns2_interrupt_regs(9), struct cdns2_usb_regs(9), struct cdns2_adma_regs(9), struct cdns2_trb(9), struct cdns2_ring(9), struct cdns2_endpoint(9), struct cdns2_request(9).

Go read those too, bestie. It's giving required reading. 💜

And that's the page, mwah 💋 this comes from ./drivers/usb/gadget/udc/cdns2, dated October 2026 — iconic source directory, iconic date, no notes. 🌈⭐