STRUCT USB_GADGET(9)                  Kernel Mode Gadget API                 STRUCT USB_GADGET(9)



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 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.

       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 AT users.net>
           Author.

COPYRIGHT
Kernel Hackers Manual 4.8.                 January 2017                      STRUCT USB_GADGET(9)