SYNOPSIS
struct usb_gadget {
struct work_struct work;
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 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 quirk_ep_out_aligned_size:1;
};
MEMBERS
work
- (internal use) Workqueue to be used for sysfs_notify
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
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.
quirk_ep_out_aligned_size
- epout requires buffer size to be aligned to MaxPacketSize.
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).
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