---
name: "struct_usb_gadget"
section: "9"
platform: "linux"
package: "linux-manual-4.9"
version: "4.9.228-1"
release: "Debian 9 (Stretch)"
platforms: ["linux"]
url: "https://new.carta.tech/struct_usb_gadget"
---

# struct\_usb\_gadget(9)

represents a usb slave device

## NAME

struct\_usb\_gadget - represents a usb slave device

## SYNOPSIS

```
struct usb_gadget {
  struct work_struct work;
  struct usb_udc * udc;
  const struct usb_gadget_ops * ops;
  struct usb_ep * ep0;
  struct list_head ep_list;
  enum usb_device_speed speed;
  enum usb_device_speed max_speed;
  enum usb_device_state state;
  const char * name;
  struct device dev;
  unsigned out_epnum;
  unsigned in_epnum;
  unsigned mA;
  struct usb_otg_caps * otg_caps;
  unsigned sg_supported:1;
  unsigned is_otg:1;
  unsigned is_a_peripheral:1;
  unsigned b_hnp_enable:1;
  unsigned a_hnp_support:1;
  unsigned a_alt_hnp_support:1;
  unsigned hnp_polling_support:1;
  unsigned host_request_flag:1;
  unsigned quirk_ep_out_aligned_size:1;
  unsigned quirk_avoids_skb_reserve:1;
  unsigned is_selfpowered:1;
  unsigned deactivated:1;
  unsigned connected:1;
};
```

## MEMBERS

work

(internal use) Workqueue to be used for **sysfs\_notify**

udc

struct usb\_udc pointer for this gadget

ops

Function pointers used to access hardware-specific operations.

ep0

Endpoint zero, used when reading or writing responses to driver **setup** requests

ep\_list

List of other endpoints supported by the device.

speed

Speed of current connection to USB host.

max\_speed

Maximal speed the UDC can handle. UDC must support this and all slower speeds.

state

the state we are now (attached, suspended, configured, etc)

name

Identifies the controller hardware type. Used in diagnostics and sometimes configuration.

dev

Driver model state for this abstract device.

out\_epnum

last used out ep number

in\_epnum

last used in ep number

mA

last set mA value

otg\_caps

OTG capabilities of this gadget.

sg\_supported

true if we can handle scatter-gather

is\_otg

True if the USB device port uses a Mini-AB jack, so that the gadget driver must provide a USB OTG descriptor.

is\_a\_peripheral

False unless is\_otg, the “A” end of a USB cable is in the Mini-AB jack, and HNP has been used to switch roles so that the “A” device currently acts as A-Peripheral, not A-Host.

b\_hnp\_enable

OTG device feature flag, indicating that the A-Host enabled HNP support.

a\_hnp\_support

OTG device feature flag, indicating that the A-Host supports HNP at this port.

a\_alt\_hnp\_support

OTG device feature flag, indicating that the A-Host only supports HNP on a different root port.

hnp\_polling\_support

OTG device feature flag, indicating if the OTG device in peripheral mode can support HNP polling.

host\_request\_flag

OTG device feature flag, indicating if A-Peripheral or B-Peripheral wants to take host role.

quirk\_ep\_out\_aligned\_size

epout requires buffer size to be aligned to MaxPacketSize.

quirk\_avoids\_skb\_reserve

udc/platform wants to avoid **skb\_reserve** in u\_ether.c to improve performance.

is\_selfpowered

if the gadget is self-powered.

deactivated

True if gadget is deactivated - in deactivated state it cannot be connected.

connected

True if gadget is connected.

## DESCRIPTION

Gadgets have a mostly-portable “gadget driver” implementing device functions, handling all usb configurations and interfaces. Gadget drivers talk to hardware-specific code indirectly, through ops vectors. That insulates the gadget driver from hardware details, and packages the hardware endpoints through generic i/o queues. The “usb\_gadget” and “usb\_ep” interfaces provide that insulation from the hardware.

Except for the driver data, all fields in this structure are read-only to the gadget driver. That driver data is part of the “driver model” infrastructure in 2.6 (and later) kernels, and for earlier systems is grouped in a similar structure that's not known to the rest of the kernel.

Values of the three OTG device feature flags are updated before the **setup** call corresponding to USB\_REQ\_SET\_CONFIGURATION, and before driver **suspend** calls. They are valid only when is\_otg, and when the device is acting as a B-Peripheral (so is\_a\_peripheral is false).

## AUTHOR

**David Brownell** \<dbrownell@users.sourceforge.net\>

Author.

## COPYRIGHT