usb_gadget.h

linux得一些常用命令,以及linux环境下的c编程

 * always corresponds to the first byte of some USB packet, for both
 * IN and OUT transfers.
 *
 * 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.
 * Attempts to halt IN endpoints will fail (returning -EAGAIN) if any
 * transfer requests are still queued, or if the controller hardware
 * (usually a FIFO) still holds bytes that the host hasn't collected.
 */
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 (and 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 is_selfpowered);
	int	(*vbus_session) (struct usb_gadget *, int is_active);
	int	(*vbus_draw) (struct usb_gadget *, unsigned mA);
	int	(*pullup) (struct usb_gadget *, int is_on);
	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.
 * @is_dualspeed: True if the controller supports both high and full speed
 *	operation.  If it does, the gadget driver must also support both.
 * @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.
 * @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.
 * @b_hnp_enable: OTG device feature flag, indicating that the A-Host
 *	enabled HNP support.
 * @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 2.6 (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).
 */
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;
	unsigned			is_dualspeed: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;
	const char			*name;

	struct device			dev;
};

static inline void set_gadget_data (struct usb_gadget *gadget, void *data)
	{ gadget->dev.driver_data = data; }
static inline void *get_gadget_data (struct usb_gadget *gadget)
	{ return gadget->dev.driver_data; }


/* 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)

#ifndef list_for_each_entry
/* not available in 2.4.18 */
#define list_for_each_entry(pos, head, member)				\
	for (pos = list_entry((head)->next, typeof(*pos), member),	\
		     prefetch(pos->member.next);			\
	     &pos->member != (head); 					\
	     pos = list_entry(pos->member.next, typeof(*pos), member),	\
		     prefetch(pos->member.next))
#endif


/**
 * 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.
 *
 * This may also try to use SRP to wake the host and start enumeration,
 * even if OTG isn't otherwise in use.  OTG devices may also start
 * remote wakeup even when hosts don't explicitly 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
 *