EFI_USBFN_IO_PROTOCOL.EventHandler

Article
03/23/2023

The EventHandler function is called repeatedly to receive updates on USB bus states, receive and transmit status changes on endpoints, and set up packet on endpoint 0.

Syntax

typedef
EFI_STATUS
(EFIAPI * EFI_USBFN_IO_EVENTHANDLER) (
  IN EFI_USBFN_IO_PROTOCOL        *This,
  OUT EFI_USBFN_MESSAGE           *Message,
  IN OUT UINTN                    *PayloadSize,
  OUT EFI_USBFN_MESSAGE_PAYLOAD   *Payload
  );

Parameters

This
A pointer to the EFI_USBFN_IO_PROTOCOL instance.

Message
A EFI_USBFN_MESSAGE value that indicates the event that initiated this notification.

PayloadSize
On input, the size of the memory pointed to by Payload. On output, the amount of data returned in Payload.

Payload
A pointer to the EFI_USBFN_MESSAGE_PAYLOAD instance to return additional payload for current message.

Return values

The function returns the following values:

Return code	Description
EFI_SUCCESS	The function returned successfully.
EFI_INVALID_PARAMETER	A parameter is invalid.
EFI_DEVICE_ERROR	The physical device reported an error.
EFI_NOT_READY	The physical device is busy or not ready to process this request.
EFI_BUFFER_TOO_SMALL	Supplied buffer not large enough to hold the message payload.

Remarks

A class driver must call EventHandler repeatedly to receive updates on the transfer status and number of bytes transferred on various endpoints. See UEFI Sequence Diagram for further information.

A few messages have associated payload that is returned in the supplied buffer. Following table describes various messages and their payload.

Message	Payload	Description
EfiUsbMsgSetupPacket	EFI_USB_DEVICE_REQUEST	SETUP packet was received.
EfiUsbMsgEndpointStatusChangedRx	EFI_USBFN_TRANSFER_RESULT	Some of the requested data has been transmitted to the host. It is the responsibility of the class driver to determine if any remaining data needs to be resent. The Buffer supplied to EFI_USBFN_IO_PROTOCOL.Transfer must be same as the Buffer field of the payload.
EfiUsbMsgEndpointStatusChangedTx	EFI_USBFN_TRANSFER_RESULT	Some of the requested data has been received from the host. It is the responsibility of the class driver to determine if it needs to wait for any remaining data. The Buffer supplied to EFI_USBFN_IO_PROTOCOL.Transfer must be same as the Buffer field of the payload.
EfiUsbMsgBusEventReset	None	RESET bus event was signaled.
EfiUsbMsgBusEventDetach	None	DETACH bus event was signaled.
EfiUsbMsgBusEventAttach	None	ATTACH bus event signaled.
EfiUsbMsgBusEventSuspend	None	SUSPEND bus event was signaled.
EfiUsbMsgBusEventResume	None	RESUME bus event signaled.
EfiUsbMsgBusEventSpeed	EFI_USB_BUS_SPEED	Bus speed update signaled.

Requirements

Header: User generated

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