usb.h

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 * @minor_base: the start of the minor range for this driver.
 *
 * This structure is used for the usb_register_dev() and
 * usb_unregister_dev() functions, to consolidate a number of the
 * parameters used for them.
 */
struct usb_class_driver {
	char *name;
	struct file_operations *fops;
	mode_t mode;
	int minor_base;	
};

/*
 * use these in module_init()/module_exit()
 * and don't forget MODULE_DEVICE_TABLE(usb, ...)
 */
extern int usb_register(struct usb_driver *);
extern void usb_deregister(struct usb_driver *);

extern int usb_register_dev(struct usb_interface *intf,
			    struct usb_class_driver *class_driver);
extern void usb_deregister_dev(struct usb_interface *intf,
			       struct usb_class_driver *class_driver);

extern int usb_disabled(void);

/* -------------------------------------------------------------------------- */

/*
 * URB support, for asynchronous request completions
 */

/*
 * urb->transfer_flags:
 */
#define URB_SHORT_NOT_OK	0x0001	/* report short reads as errors */
#define URB_ISO_ASAP		0x0002	/* iso-only, urb->start_frame ignored */
#define URB_NO_TRANSFER_DMA_MAP	0x0004	/* urb->transfer_dma valid on submit */
#define URB_NO_SETUP_DMA_MAP	0x0008	/* urb->setup_dma valid on submit */
#define URB_NO_FSBR		0x0020	/* UHCI-specific */
#define URB_ZERO_PACKET		0x0040	/* Finish bulk OUTs with short packet */
#define URB_NO_INTERRUPT	0x0080	/* HINT: no non-error interrupt needed */

struct usb_iso_packet_descriptor {
	unsigned int offset;
	unsigned int length;		/* expected length */
	unsigned int actual_length;
	unsigned int status;
};

struct urb;
struct pt_regs;

typedef void (*usb_complete_t)(struct urb *, struct pt_regs *);

/**
 * struct urb - USB Request Block
 * @urb_list: For use by current owner of the URB.
 * @pipe: Holds endpoint number, direction, type, and more.
 *	Create these values with the eight macros available;
 *	usb_{snd,rcv}TYPEpipe(dev,endpoint), where the TYPE is "ctrl"
 *	(control), "bulk", "int" (interrupt), or "iso" (isochronous).
 *	For example usb_sndbulkpipe() or usb_rcvintpipe().  Endpoint
 *	numbers range from zero to fifteen.  Note that "in" endpoint two
 *	is a different endpoint (and pipe) from "out" endpoint two.
 *	The current configuration controls the existence, type, and
 *	maximum packet size of any given endpoint.
 * @dev: Identifies the USB device to perform the request.
 * @status: This is read in non-iso completion functions to get the
 *	status of the particular request.  ISO requests only use it
 *	to tell whether the URB was unlinked; detailed status for
 *	each frame is in the fields of the iso_frame-desc.
 * @transfer_flags: A variety of flags may be used to affect how URB
 *	submission, unlinking, or operation are handled.  Different
 *	kinds of URB can use different flags.
 * @transfer_buffer:  This identifies the buffer to (or from) which
 * 	the I/O request will be performed (unless URB_NO_TRANSFER_DMA_MAP
 *	is set).  This buffer must be suitable for DMA; allocate it with
 *	kmalloc() or equivalent.  For transfers to "in" endpoints, contents
 *	of this buffer will be modified.  This buffer is used for the data
 *	stage of control transfers.
 * @transfer_dma: When transfer_flags includes URB_NO_TRANSFER_DMA_MAP,
 *	the device driver is saying that it provided this DMA address,
 *	which the host controller driver should use in preference to the
 *	transfer_buffer.
 * @transfer_buffer_length: How big is transfer_buffer.  The transfer may
 *	be broken up into chunks according to the current maximum packet
 *	size for the endpoint, which is a function of the configuration
 *	and is encoded in the pipe.  When the length is zero, neither
 *	transfer_buffer nor transfer_dma is used.
 * @actual_length: This is read in non-iso completion functions, and
 *	it tells how many bytes (out of transfer_buffer_length) were
 *	transferred.  It will normally be the same as requested, unless
 *	either an error was reported or a short read was performed.
 *	The URB_SHORT_NOT_OK transfer flag may be used to make such
 *	short reads be reported as errors. 
 * @setup_packet: Only used for control transfers, this points to eight bytes
 *	of setup data.  Control transfers always start by sending this data
 *	to the device.  Then transfer_buffer is read or written, if needed.
 * @setup_dma: For control transfers with URB_NO_SETUP_DMA_MAP set, the
 *	device driver has provided this DMA address for the setup packet.
 *	The host controller driver should use this in preference to
 *	setup_packet.
 * @start_frame: Returns the initial frame for isochronous transfers.
 * @number_of_packets: Lists the number of ISO transfer buffers.
 * @interval: Specifies the polling interval for interrupt or isochronous
 *	transfers.  The units are frames (milliseconds) for for full and low
 *	speed devices, and microframes (1/8 millisecond) for highspeed ones.
 * @error_count: Returns the number of ISO transfers that reported errors.
 * @context: For use in completion functions.  This normally points to
 *	request-specific driver context.
 * @complete: Completion handler. This URB is passed as the parameter to the
 *	completion function.  The completion function may then do what
 *	it likes with the URB, including resubmitting or freeing it.
 * @iso_frame_desc: Used to provide arrays of ISO transfer buffers and to 
 *	collect the transfer status for each buffer.
 *
 * This structure identifies USB transfer requests.  URBs must be allocated by
 * calling usb_alloc_urb() and freed with a call to usb_free_urb().
 * Initialization may be done using various usb_fill_*_urb() functions.  URBs
 * are submitted using usb_submit_urb(), and pending requests may be canceled
 * using usb_unlink_urb() or usb_kill_urb().
 *
 * Data Transfer Buffers:
 *
 * Normally drivers provide I/O buffers allocated with kmalloc() or otherwise
 * taken from the general page pool.  That is provided by transfer_buffer
 * (control requests also use setup_packet), and host controller drivers
 * perform a dma mapping (and unmapping) for each buffer transferred.  Those
 * mapping operations can be expensive on some platforms (perhaps using a dma
 * bounce buffer or talking to an IOMMU),
 * although they're cheap on commodity x86 and ppc hardware.
 *
 * Alternatively, drivers may pass the URB_NO_xxx_DMA_MAP transfer flags,
 * which tell the host controller driver that no such mapping is needed since
 * the device driver is DMA-aware.  For example, a device driver might
 * allocate a DMA buffer with usb_buffer_alloc() or call usb_buffer_map().
 * When these transfer flags are provided, host controller drivers will
 * attempt to use the dma addresses found in the transfer_dma and/or
 * setup_dma fields rather than determining a dma address themselves.  (Note
 * that transfer_buffer and setup_packet must still be set because not all
 * host controllers use DMA, nor do virtual root hubs).
 *
 * Initialization:
 *
 * All URBs submitted must initialize the dev, pipe, transfer_flags (may be
 * zero), and complete fields.  All URBs must also initialize
 * transfer_buffer and transfer_buffer_length.  They may provide the
 * URB_SHORT_NOT_OK transfer flag, indicating that short reads are
 * to be treated as errors; that flag is invalid for write requests.
 *
 * Bulk URBs may
 * use the URB_ZERO_PACKET transfer flag, indicating that bulk OUT transfers
 * should always terminate with a short packet, even if it means adding an
 * extra zero length packet.
 *
 * Control URBs must provide a setup_packet.  The setup_packet and
 * transfer_buffer may each be mapped for DMA or not, independently of
 * the other.  The transfer_flags bits URB_NO_TRANSFER_DMA_MAP and
 * URB_NO_SETUP_DMA_MAP indicate which buffers have already been mapped.
 * URB_NO_SETUP_DMA_MAP is ignored for non-control URBs.
 *
 * Interrupt URBs must provide an interval, saying how often (in milliseconds
 * or, for highspeed devices, 125 microsecond units)
 * to poll for transfers.  After the URB has been submitted, the interval
 * field reflects how the transfer was actually scheduled.
 * The polling interval may be more frequent than requested.
 * For example, some controllers have a maximum interval of 32 milliseconds,
 * while others support intervals of up to 1024 milliseconds.
 * Isochronous URBs also have transfer intervals.  (Note that for isochronous
 * endpoints, as well as high speed interrupt endpoints, the encoding of
 * the transfer interval in the endpoint descriptor is logarithmic.
 * Device drivers must convert that value to linear units themselves.)
 *
 * Isochronous URBs normally use the URB_ISO_ASAP transfer flag, telling
 * the host controller to schedule the transfer as soon as bandwidth
 * utilization allows, and then set start_frame to reflect the actual frame
 * selected during submission.  Otherwise drivers must specify the start_frame
 * and handle the case where the transfer can't begin then.  However, drivers
 * won't know how bandwidth is currently allocated, and while they can
 * find the current frame using usb_get_current_frame_number () they can't
 * know the range for that frame number.  (Ranges for frame counter values
 * are HC-specific, and can go from 256 to 65536 frames from "now".)
 *
 * Isochronous URBs have a different data transfer model, in part because
 * the quality of service is only "best effort".  Callers provide specially
 * allocated URBs, with number_of_packets worth of iso_frame_desc structures
 * at the end.  Each such packet is an individual ISO transfer.  Isochronous
 * URBs are normally queued, submitted by drivers to arrange that
 * transfers are at least double buffered, and then explicitly resubmitted
 * in completion handlers, so
 * that data (such as audio or video) streams at as constant a rate as the
 * host controller scheduler can support.
 *
 * Completion Callbacks:
 *
 * The completion callback is made in_interrupt(), and one of the first
 * things that a completion handler should do is check the status field.
 * The status field is provided for all URBs.  It is used to report
 * unlinked URBs, and status for all non-ISO transfers.  It should not
 * be examined before the URB is returned to the completion handler.
 *
 * The context field is normally used to link URBs back to the relevant
 * driver or request state.
 *
 * When the completion callback is invoked for non-isochronous URBs, the
 * actual_length field tells how many bytes were transferred.  This field
 * is updated even when the URB terminated with an error or was unlinked.
 *
 * ISO transfer status is reported in the status and actual_length fields
 * of the iso_frame_desc array, and the number of errors is reported in
 * error_count.  Completion callbacks for ISO transfers will normally
 * (re)submit URBs to ensure a constant transfer rate.
 *
 * Note that even fields marked "public" should not be touched by the driver
 * when the urb is owned by the hcd, that is, since the call to
 * usb_submit_urb() till the entry into the completion routine.
 */
struct urb
{
	/* private, usb core and host controller only fields in the urb */
	struct kref kref;		/* reference count of the URB */
	spinlock_t lock;		/* lock for the URB */
	void *hcpriv;			/* private data for host controller */
	int bandwidth;			/* bandwidth for INT/ISO request */
	atomic_t use_count;		/* concurrent submissions counter */
	u8 reject;			/* submissions will fail */

	/* public, documented fields in the urb that can be used by drivers */
	struct list_head urb_list;	/* list head for use by the urb owner */
	struct usb_device *dev; 	/* (in) pointer to associated device */
	unsigned int pipe;		/* (in) pipe information */
	int status;			/* (return) non-ISO status */
	unsigned int transfer_flags;	/* (in) URB_SHORT_NOT_OK | ...*/
	void *transfer_buffer;		/* (in) associated data buffer */
	dma_addr_t transfer_dma;	/* (in) dma addr for transfer_buffer */
	int transfer_buffer_length;	/* (in) data buffer length */
	int actual_length;		/* (return) actual transfer length */
	unsigned char *setup_packet;	/* (in) setup packet (control only) */
	dma_addr_t setup_dma;		/* (in) dma addr for setup_packet */
	int start_frame;		/* (modify) start frame (ISO) */
	int number_of_packets;		/* (in) number of ISO packets */
	int interval;			/* (modify) transfer interval (INT/ISO) */
	int error_count;		/* (return) number of ISO errors */
	void *context;			/* (in) context for completion */
	usb_complete_t complete;	/* (in) completion routine */
	struct usb_iso_packet_descriptor iso_frame_desc[0];	/* (in) ISO ONLY */
};

/* -------------------------------------------------------------------------- */

/**
 * usb_fill_control_urb - initializes a control urb
 * @urb: pointer to the urb to initialize.
 * @dev: pointer to the struct usb_device for this urb.
 * @pipe: the endpoint pipe
 * @setup_packet: pointer to the setup_packet buffer
 * @transfer_buffer: pointer to the transfer buffer
 * @buffer_length: length of the transfer buffer
 * @complete: pointer to the usb_complete_t function
 * @context: what to set the urb context to.
 *
 * Initializes a control urb with the proper information needed to submit
 * it to a device.
 */
static inline void usb_fill_control_urb (struct urb *urb,
					 struct usb_device *dev,
					 unsigned int pipe,
					 unsigned char *setup_packet,
					 void *transfer_buffer,
					 int buffer_length,
					 usb_complete_t complete,
					 void *context)
{
	spin_lock_init(&urb->lock);
	urb->dev = dev;
	urb->pipe = pipe;
	urb->setup_packet = setup_packet;
	urb->transfer_buffer = transfer_buffer;
	urb->transfer_buffer_length = buffer_length;
	urb->complete = complete;
	urb->context = context;
}

/**
 * usb_fill_bulk_urb - macro to help initialize a bulk urb
 * @urb: pointer to the urb to initialize.
 * @dev: pointer to the struct usb_device for this urb.