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/*
* <linux/usb_gadget.h>
*
* We call the USB code inside a Linux-based peripheral device a "gadget"
* driver, except for the hardware-specific bus glue. One USB host can
* master many USB gadgets, but the gadgets are only slaved to one host.
*
*
* (c) Copyright 2002-2003 by David Brownell
* All Rights Reserved.
*
* This software is licensed under the GNU GPL version 2.
*/
#ifndef __LINUX_USB_GADGET_H
#define __LINUX_USB_GADGET_H
#ifdef __KERNEL__
struct usb_ep;
/**
* struct usb_request - describes one i/o request
* @buf: Buffer used for data. Always provide this; some controllers
* only use PIO, or don't use DMA for some endpoints.
* @dma: DMA address corresponding to 'buf'. If you don't set this
* field, and the usb controller needs one, it is responsible
* for mapping and unmapping the buffer.
* @length: Length of that data
* @no_interrupt: If true, hints that no completion irq is needed.
* Helpful sometimes with deep request queues.
* @zero: If true, when writing data, makes the last packet be "short"
* by adding a zero length packet as needed;
* @short_not_ok: When reading data, makes short packets be
* treated as errors (queue stops advancing till cleanup).
* @complete: Function called when request completes
* @context: For use by the completion callback
* @list: For use by the gadget driver.
* @status: Reports completion code, zero or a negative errno.
* Normally, faults block the transfer queue from advancing until
* the completion callback returns.
* Code "-ESHUTDOWN" indicates completion caused by device disconnect,
* or when the driver disabled the endpoint.
* @actual: Reports actual bytes transferred. For reads (OUT
* transfers) this may be less than the requested length. If the
* short_not_ok flag is set, short reads are treated as errors
* even when status otherwise indicates successful completion.
* Note that for writes (IN transfers) the data bytes may still
* reside in a device-side FIFO.
*
* These are allocated/freed through the endpoint they're used with. The
* hardware's driver can add extra per-request data to the memory it returns,
* which often avoids separate memory allocations (potential failures),
* later when the request is queued.
*
* Request flags affect request handling, such as whether a zero length
* packet is written (the "zero" flag), whether a short read should be
* treated as an error (blocking request queue advance, the "short_not_ok"
* flag), or hinting that an interrupt is not required (the "no_interrupt"
* flag, for use with deep request queues).
*
* Bulk endpoints can use any size buffers, and can also be used for interrupt
* transfers. interrupt-only endpoints can be much less functional.
*/
// NOTE this is analagous to 'struct urb' on the host side,
// except that it's thinner and promotes more pre-allocation.
//
// ISSUE should this be allocated through the device?
struct usb_request {
void *buf;
unsigned length;
dma_addr_t dma;
unsigned no_interrupt:1;
unsigned zero:1;
unsigned short_not_ok:1;
void (*complete)(struct usb_ep *ep,
struct usb_request *req);
void *context;
struct list_head list;
int status;
unsigned actual;
};
/*-------------------------------------------------------------------------*/
/* endpoint-specific parts of the api to the usb controller hardware.
* unlike the urb model, (de)multiplexing layers are not required.
* (so this api could slash overhead if used on the host side...)
*
* note that device side usb controllers commonly differ in how many
* endpoints they support, as well as their capabilities.
*/
struct usb_ep_ops {
int (*enable) (struct usb_ep *ep,
const struct usb_endpoint_descriptor *desc);
int (*disable) (struct usb_ep *ep);
struct usb_request *(*alloc_request) (struct usb_ep *ep,
int gfp_flags);
void (*free_request) (struct usb_ep *ep, struct usb_request *req);
void *(*alloc_buffer) (struct usb_ep *ep, unsigned bytes,
dma_addr_t *dma, int gfp_flags);
void (*free_buffer) (struct usb_ep *ep, void *buf, dma_addr_t dma,
unsigned bytes);
// NOTE: on 2.5, drivers may also use dma_map() and
// dma_sync_single() to manage dma overhead.
int (*queue) (struct usb_ep *ep, struct usb_request *req,
int gfp_flags);
int (*dequeue) (struct usb_ep *ep, struct usb_request *req);
int (*set_halt) (struct usb_ep *ep, int value);
int (*fifo_status) (struct usb_ep *ep);
void (*fifo_flush) (struct usb_ep *ep);
};
/**
* struct usb_ep - device side representation of USB endpoint
* @name:identifier for the endpoint, such as "ep-a" or "ep9in-bulk"
* @ops: Function pointers used to access hardware-specific operations.
* @ep_list:the gadget's ep_list holds all of its endpoints
* @maxpacket:The maximum packet size used on this endpoint. The initial
* value can sometimes be reduced (hardware allowing), according to
* the endpoint descriptor used to configure the endpoint.
* @driver_data:for use by the gadget driver. all other fields are
* read-only to gadget drivers.
*
* the bus controller driver lists all the general purpose endpoints in
* gadget->ep_list. the control endpoint (gadget->ep0) is not in that list,
* and is accessed only in response to a driver setup() callback.
*/
struct usb_ep {
void *driver_data;
const char *name;
const struct usb_ep_ops *ops;
struct list_head ep_list;
unsigned maxpacket:16;
};
/*-------------------------------------------------------------------------*/
/**
* usb_ep_enable - configure endpoint, making it usable
* @ep:the endpoint being configured. may not be the endpoint named "ep0".
* drivers discover endpoints through the ep_list of a usb_gadget.
* @desc:descriptor for desired behavior. caller guarantees this pointer
* remains valid until the endpoint is disabled; the data byte order
* is little-endian (usb-standard).
*
* when configurations are set, or when interface settings change, the driver
* will enable or disable the relevant endpoints. while it is enabled, an
* endpoint may be used for i/o until the driver receives a disconnect() from
* the host or until the endpoint is disabled.
*
* the ep0 implementation (which calls this routine) must ensure that the
* hardware capabilities of each endpoint match the descriptor provided
* for it. for example, an endpoint named "ep2in-bulk" would be usable
* for interrupt transfers as well as bulk, but it likely couldn't be used
* for iso transfers or for endpoint 14. some endpoints are fully
* configurable, with more generic names like "ep-a". (remember that for
* USB, "in" means "towards the USB master".)
*
* returns zero, or a negative error code.
*/
static inline int
usb_ep_enable (struct usb_ep *ep, const struct usb_endpoint_descriptor *desc)
{
return ep->ops->enable (ep, desc);
}
/**
* usb_ep_disable - endpoint is no longer usable
* @ep:the endpoint being unconfigured. may not be the endpoint named "ep0".
*
* no other task may be using this endpoint when this is called.
* any pending and uncompleted requests will complete with status
* indicating disconnect (-ESHUTDOWN) before this call returns.
* gadget drivers must call usb_ep_enable() again before queueing
* requests to the endpoint.
*
* returns zero, or a negative error code.
*/
static inline int
usb_ep_disable (struct usb_ep *ep)
{
return ep->ops->disable (ep);
}
/**
* usb_ep_alloc_request - allocate a request object to use with this endpoint
* @ep:the endpoint to be used with with the request
* @gfp_flags:GFP_* flags to use
*
* Request objects must be allocated with this call, since they normally
* need controller-specific setup and may even need endpoint-specific
* resources such as allocation of DMA descriptors.
* Requests may be submitted with usb_ep_queue(), and receive a single
* completion callback. Free requests with usb_ep_free_request(), when
* they are no longer needed.
*
* Returns the request, or null if one could not be allocated.
*/
static inline struct usb_request *
usb_ep_alloc_request (struct usb_ep *ep, int gfp_flags)
{
return ep->ops->alloc_request (ep, gfp_flags);
}
/**
* usb_ep_free_request - frees a request object
* @ep:the endpoint associated with the request
* @req:the request being freed
*
* Reverses the effect of usb_ep_alloc_request().
* Caller guarantees the request is not queued, and that it will
* no longer be requeued (or otherwise used).
*/
static inline void
usb_ep_free_request (struct usb_ep *ep, struct usb_request *req)
{
ep->ops->free_request (ep, req);
}
/**
* usb_ep_alloc_buffer - allocate an I/O buffer
* @ep:the endpoint associated with the buffer
* @len:length of the desired buffer
* @dma:pointer to the buffer's DMA address; must be valid
* @gfp_flags:GFP_* flags to use
*
* Returns a new buffer, or null if one could not be allocated.
* The buffer is suitably aligned for dma, if that endpoint uses DMA,
* and the caller won't have to care about dma-inconsistency
* or any hidden "bounce buffer" mechanism. No additional per-request
* DMA mapping will be required for such buffers.
* Free it later with usb_ep_free_buffer().
*
* You don't need to use this call to allocate I/O buffers unless you
* want to make sure drivers don't incur costs for such "bounce buffer"
* copies or per-request DMA mappings.
*/
static inline void *
usb_ep_alloc_buffer (struct usb_ep *ep, unsigned len, dma_addr_t *dma,
int gfp_flags)
{
return ep->ops->alloc_buffer (ep, len, dma, gfp_flags);
}
/**
* usb_ep_free_buffer - frees an i/o buffer
* @ep:the endpoint associated with the buffer
* @buf:CPU view address of the buffer
* @dma:the buffer's DMA address
* @len:length of the buffer
*
* reverses the effect of usb_ep_alloc_buffer().
* caller guarantees the buffer will no longer be accessed
*/
static inline void
usb_ep_free_buffer (struct usb_ep *ep, void *buf, dma_addr_t dma, unsigned len)
{
ep->ops->free_buffer (ep, buf, dma, len);
}
/**
* usb_ep_queue - queues (submits) an I/O request to an endpoint.
* @ep:the endpoint associated with the request
* @req:the request being submitted
* @gfp_flags: GFP_* flags to use in case the lower level driver couldn't
* pre-allocate all necessary memory with the request.
*
* This tells the device controller to perform the specified request through
* that endpoint (reading or writing a buffer). When the request completes,
* including being canceled by usb_ep_dequeue(), the request's completion
* routine is called to return the request to the driver. Any endpoint
* (except control endpoints like ep0) may have more than one transfer
* request queued; they complete in FIFO order. Once a gadget driver
* submits a request, that request may not be examined or modified until it
* is given back to that driver through the completion callback.
*
* Each request is turned into one or more packets. The controller driver
* never merges adjacent requests into the same packet. OUT transfers
* will sometimes use data that's already buffered in the hardware.
*
* Bulk endpoints can queue any amount of data; the transfer is packetized
* automatically. The last packet will be short if the request doesn't fill it
* out completely. Zero length packets (ZLPs) should be avoided in portable
* protocols since not all usb hardware can successfully handle zero length
* packets. (ZLPs may be explicitly written, and may be implicitly written if
* the request 'zero' flag is set.) Bulk endpoints may also be used
* for interrupt transfers; but the reverse is not true, and some endpoints
* won't support every interrupt transfer. (Such as 768 byte packets.)
*
* Interrupt-only endpoints are less functional than bulk endpoints, for
* example by not supporting queueing or not handling buffers that are
* larger than the endpoint's maxpacket size. They may also treat data
* toggle differently.
*
* Control endpoints ... after getting a setup() callback, the driver queues
* one response (even if it would be zero length). That enables the
* status ack, after transfering data as specified in the response. Setup
* functions may return negative error codes to generate protocol stalls.
* (Note that some USB device controllers disallow protocol stall responses
* in some cases.) When control responses are deferred (the response is
* written after the setup callback returns), then usb_ep_set_halt() may be
* used on ep0 to trigger protocol stalls.
*
* For periodic endpoints, like interrupt or isochronous ones, the usb host
* arranges to poll once per interval, and the gadget driver usually will
* have queued some data to transfer at that time.
*
* Returns zero, or a negative error code. Endpoints that are not enabled
* report errors; errors will also be
* reported when the usb peripheral is disconnected.
*/
static inline int
usb_ep_queue (struct usb_ep *ep, struct usb_request *req, int gfp_flags)
{
return ep->ops->queue (ep, req, gfp_flags);
}
/**
* usb_ep_dequeue - dequeues (cancels, unlinks) an I/O request from an endpoint
* @ep:the endpoint associated with the request
* @req:the request being canceled
*
* if the request is still active on the endpoint, it is dequeued and its
* completion routine is called (with status -ECONNRESET); else a negative
* error code is returned.
*
* note that some hardware can't clear out write fifos (to unlink the request
* at the head of the queue) except as part of disconnecting from usb. such
* restrictions prevent drivers from supporting configuration changes,
* even to configuration zero (a "chapter 9" requirement).
*/
static inline int usb_ep_dequeue (struct usb_ep *ep, struct usb_request *req)
{
return ep->ops->dequeue (ep, req);
}
/**
* usb_ep_set_halt - sets the endpoint halt feature.
* @ep: the non-isochronous endpoint being stalled
*
* Use this to stall an endpoint, perhaps as an error report.
* Except for control endpoints,
* the endpoint stays halted (will not stream any data) until the host
* clears this feature; drivers may need to empty the endpoint's request
* queue first, to make sure no inappropriate transfers happen.
*
* Note that while an endpoint CLEAR_FEATURE will be invisible to the
* gadget driver, a SET_INTERFACE will not be. To reset endpoints for the
* current altsetting, see usb_ep_clear_halt(). When switching altsettings,
* it's simplest to use usb_ep_enable() or usb_ep_disable() for the endpoints.
*
* Returns zero, or a negative error code. On success, this call sets
* underlying hardware state that blocks data transfers.
*/
static inline int
usb_ep_set_halt (struct usb_ep *ep)
{
return ep->ops->set_halt (ep, 1);
}
/**
* usb_ep_clear_halt - clears endpoint halt, and resets toggle
* @ep:the bulk or interrupt endpoint being reset
*
* Use this when responding to the standard usb "set interface" request,
* for endpoints that aren't reconfigured, after clearing any other state
* in the endpoint's i/o queue.
*
* Returns zero, or a negative error code. On success, this call clears
* the underlying hardware state reflecting endpoint halt and data toggle.
* Note that some hardware can't support this request (like pxa2xx_udc),
* and accordingly can't correctly implement interface altsettings.
*/
static inline int
usb_ep_clear_halt (struct usb_ep *ep)
{
return ep->ops->set_halt (ep, 0);
}
/**
* usb_ep_fifo_status - returns number of bytes in fifo, or error
* @ep: the endpoint whose fifo status is being checked.
*
* FIFO endpoints may have "unclaimed data" in them in certain cases,
* such as after aborted transfers. Hosts may not have collected all
* the IN data written by the gadget driver, as reported by a request
* completion. The gadget driver may not have collected all the data
* written OUT to it by the host. Drivers that need precise handling for
* fault reporting or recovery may need to use this call.
*
* This returns the number of such bytes in the fifo, or a negative
* errno if the endpoint doesn't use a FIFO or doesn't support such
* precise handling.
*/
static inline int
usb_ep_fifo_status (struct usb_ep *ep)
{
if (ep->ops->fifo_status)
return ep->ops->fifo_status (ep);
else
return -EOPNOTSUPP;
}
/**
* usb_ep_fifo_flush - flushes contents of a fifo
* @ep: the endpoint whose fifo is being flushed.
*
* This call may be used to flush the "unclaimed data" that may exist in
* an endpoint fifo after abnormal transaction terminations. The call
* must never be used except when endpoint is not being used for any
* protocol translation.
*/
static inline void
usb_ep_fifo_flush (struct usb_ep *ep)
{
if (ep->ops->fifo_flush)
ep->ops->fifo_flush (ep);
}
/*-------------------------------------------------------------------------*/
struct usb_gadget;
/* the rest of the api to the controller hardware: device operations,
* which don't involve endpoints (or i/o).
*/
struct usb_gadget_ops {
int (*get_frame)(struct usb_gadget *);
int (*wakeup)(struct usb_gadget *);
int (*set_selfpowered) (struct usb_gadget *, int value);
int (*ioctl)(struct usb_gadget *,
unsigned code, unsigned long param);
};
/**
* struct usb_gadget - represents a usb slave device
* @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.
* @name: Identifies the controller hardware type. Used in diagnostics
* and sometimes configuration.
* @dev: Driver model state for this abstract device.
*
* 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 2.5 (and later) kernels, and for
* earlier systems is grouped in a similar structure that's not known
* to the rest of the kernel.
*/
struct usb_gadget {
/* readonly to gadget driver */
const struct usb_gadget_ops *ops;
struct usb_ep *ep0;
struct list_head ep_list; /* of usb_ep */
enum usb_device_speed speed;
const char *name;
struct device dev;
};
static inline void set_gadget_data (struct usb_gadget *gadget, void *data)
{ dev_set_drvdata (&gadget->dev, data); }
static inline void *get_gadget_data (struct usb_gadget *gadget)
{ return dev_get_drvdata (&gadget->dev); }
/* iterates the non-control endpoints; 'tmp' is a struct usb_ep pointer */
#define gadget_for_each_ep(tmp,gadget) \
list_for_each_entry(tmp, &(gadget)->ep_list, ep_list)
/**
* usb_gadget_frame_number - returns the current frame number
* @gadget: controller that reports the frame number
*
* Returns the usb frame number, normally eleven bits from a SOF packet,
* or negative errno if this device doesn't support this capability.
*/
static inline int usb_gadget_frame_number (struct usb_gadget *gadget)
{
return gadget->ops->get_frame (gadget);
}
/**
* usb_gadget_wakeup - tries to wake up the host connected to this gadget
* @gadget: controller used to wake up the host
*
* Returns zero on success, else negative error code if the hardware
* doesn't support such attempts, or its support has not been enabled
* by the usb host. Drivers must return device descriptors that report
* their ability to support this, or hosts won't enable it.
*/
static inline int usb_gadget_wakeup (struct usb_gadget *gadget)
{
if (!gadget->ops->wakeup)
return -EOPNOTSUPP;
return gadget->ops->wakeup (gadget);
}
/**
* usb_gadget_set_selfpowered - sets the device selfpowered feature.
* @gadget:the device being declared as self-powered
*
* this affects the device status reported by the hardware driver
* to reflect that it now has a local power supply.
*
* returns zero on success, else negative errno.
*/
static inline int
usb_gadget_set_selfpowered (struct usb_gadget *gadget)
{
if (!gadget->ops->set_selfpowered)
return -EOPNOTSUPP;
return gadget->ops->set_selfpowered (gadget, 1);
}
/**
* usb_gadget_clear_selfpowered - clear the device selfpowered feature.
* @gadget:the device being declared as bus-powered
*
* this affects the device status reported by the hardware driver.
* some hardware may not support bus-powered operation, in which
* case this feature's value can never change.
*
* returns zero on success, else negative errno.
*/
static inline int
usb_gadget_clear_selfpowered (struct usb_gadget *gadget)
{
if (!gadget->ops->set_selfpowered)
return -EOPNOTSUPP;
return gadget->ops->set_selfpowered (gadget, 0);
}
/*-------------------------------------------------------------------------*/
/**
* struct usb_gadget_driver - driver for usb 'slave' devices
* @function: String describing the gadget's function
* @speed: Highest speed the driver handles.
* @bind: Invoked when the driver is bound to a gadget, usually
* after registering the driver.
* At that point, ep0 is fully initialized, and ep_list holds
* the currently-available endpoints.
* Called in a context that permits sleeping.
* @setup: Invoked for ep0 control requests that aren't handled by
* the hardware level driver. Most calls must be handled by
* the gadget driver, including descriptor and configuration
* management. The 16 bit members of the setup data are in
* cpu order. Called in_interrupt; this may not sleep. Driver
* queues a response to ep0, or returns negative to stall.
* @disconnect: Invoked after all transfers have been stopped,
* when the host is disconnected. May be called in_interrupt; this
* may not sleep. Some devices can't detect disconnect, so this might
* not be called except as part of controller shutdown.
* @unbind: Invoked when the driver is unbound from a gadget,
* usually from rmmod (after a disconnect is reported).
* Called in a context that permits sleeping.
* @suspend: Invoked on USB suspend. May be called in_interrupt.
* @resume: Invoked on USB resume. May be called in_interrupt.
* @driver: Driver model state for this driver.
*
* Devices are disabled till a gadget driver successfully bind()s, which
* means the driver will handle setup() requests needed to enumerate (and
* meet "chapter 9" requirements) then do some useful work.
*
* Drivers use hardware-specific knowledge to configure the usb hardware.
* endpoint addressing is only one of several hardware characteristics that
* are in descriptors the ep0 implementation returns from setup() calls.
*
* Except for ep0 implementation, most driver code shouldn't need change to
* run on top of different usb controllers. It'll use endpoints set up by
* that ep0 implementation.
*
* The usb controller driver handles a few standard usb requests. Those
* include set_address, and feature flags for devices, interfaces, and
* endpoints (the get_status, set_feature, and clear_feature requests).
*
* Accordingly, the driver's setup() callback must always implement all
* get_descriptor requests, returning at least a device descriptor and
* a configuration descriptor. Drivers must make sure the endpoint
* descriptors match any hardware constraints. Some hardware also constrains
* other descriptors. (The pxa250 allows only configurations 1, 2, or 3).
*
* The driver's setup() callback must also implement set_configuration,
* and should also implement set_interface, get_configuration, and
* get_interface. Setting a configuration (or interface) is where
* endpoints should be activated or (config 0) shut down.
*
* (Note that only the default control endpoint is supported. Neither
* hosts nor devices generally support control traffic except to ep0.)
*
* Most devices will ignore USB suspend/resume operations, and so will
* not provide those callbacks. However, some may need to change modes
* when the host is not longer directing those activities. For example,
* local controls (buttons, dials, etc) may need to be re-enabled since
* the (remote) host can't do that any longer; or an error state might
* be cleared, to make the device behave identically whether or not
* power is maintained.
*/
struct usb_gadget_driver {
char *function;
enum usb_device_speed speed;
int (*bind)(struct usb_gadget *);
void (*unbind)(struct usb_gadget *);
int (*setup)(struct usb_gadget *,
const struct usb_ctrlrequest *);
void (*disconnect)(struct usb_gadget *);
void (*suspend)(struct usb_gadget *);
void (*resume)(struct usb_gadget *);
// FIXME support safe rmmod
struct device_driver driver;
};
/*-------------------------------------------------------------------------*/
/* driver modules register and unregister, as usual.
* these calls must be made in a context that can sleep.
*
* these will usually be implemented directly by the hardware-dependent
* usb bus interface driver, which will only support a single driver.
*/
/**
* usb_gadget_register_driver - register a gadget driver
* @driver:the driver being registered
*
* Call this in your gadget driver's module initialization function,
* to tell the underlying usb controller driver about your driver.
* The driver's bind() function will be called to bind it to a
* gadget. This function must be called in a context that can sleep.
*/
int usb_gadget_register_driver (struct usb_gadget_driver *driver);
/**
* usb_gadget_unregister_driver - unregister a gadget driver
* @driver:the driver being unregistered
*
* Call this in your gadget driver's module cleanup function,
* to tell the underlying usb controller that your driver is
* going away. If the controller is connected to a USB host,
* it will first disconnect(). The driver is also requested
* to unbind() and clean up any device state, before this procedure
* finally returns.
* This function must be called in a context that can sleep.
*/
int usb_gadget_unregister_driver (struct usb_gadget_driver *driver);
/*-------------------------------------------------------------------------*/
/* utility to simplify dealing with string descriptors */
/**
* struct usb_string - wraps a C string and its USB id
* @id:the (nonzero) ID for this string
* @s:the string, in ISO-8859/1 characters
*
* If you're using usb_gadget_get_string(), use this to wrap a string
* together with its ID.
*/
struct usb_string {
u8 id;
const char *s;
};
/**
* struct usb_gadget_strings - a set of USB strings in a given language
* @language:identifies the strings' language (0x0409 for en-us)
* @strings:array of strings with their ids
*
* If you're using usb_gadget_get_string(), use this to wrap all the
* strings for a given language.
*/
struct usb_gadget_strings {
u16 language; /* 0x0409 for en-us */
struct usb_string *strings;
};
/* put descriptor for string with that id into buf (buflen >= 256) */
int usb_gadget_get_string (struct usb_gadget_strings *table, int id, u8 *buf);
#endif /* __KERNEL__ */
#endif /* __LINUX_USB_GADGET_H */