Provided by: freebsd-manpages_7.1~beta1-1_all bug

NAME

     usb_detach_wait, usb_detach_wakeup, usb_find_desc,
     usbd_abort_default_pipe, usbd_abort_pipe, usbd_alloc_buffer,
     usbd_alloc_xfer, usbd_bulk_transfer, usbd_clear_endpoint_stall,
     usbd_clear_endpoint_stall_async, usbd_clear_endpoint_toggle,
     usbd_close_pipe, usbd_device2interface_handle, usbd_devinfo,
     usbd_do_request, usbd_do_request_async, usbd_do_request_flags,
     usbd_do_request_flags_pipe, usbd_dopoll, usbd_endpoint_count,
     usbd_errstr, usbd_fill_deviceinfo, usbd_find_edesc, usbd_find_idesc,
     usbd_free_buffer, usbd_free_xfer, usbd_get_buffer, usbd_get_config,
     usbd_get_config_desc, usbd_get_config_desc_full,
     usbd_get_config_descriptor, usbd_get_device_descriptor,
     usbd_get_endpoint_descriptor, usbd_get_interface_altindex,
     usbd_get_interface_descriptor, usbd_get_no_alts, usbd_get_quirks,
     usbd_get_speed, usbd_get_string, usbd_get_string_desc,
     usbd_get_xfer_status, usbd_interface2device_handle,
     usbd_interface2endpoint_descriptor, usbd_interface_count,
     usbd_intr_transfer, usbd_open_pipe, usbd_open_pipe_intr,
     usbd_pipe2device_handle, usbd_ratecheck, usbd_set_config_index,
     usbd_set_config_no, usbd_set_interface, usbd_set_polling,
     usbd_setup_default_xfer, usbd_setup_isoc_xfer, usbd_setup_xfer,
     usbd_sync_transfer, usbd_transfer - Universal Serial Bus driver
     programming interface

SYNOPSIS

     #include <dev/usb/usb.h>
     #include <dev/usb/usbdi.h>
     #include <dev/usb/usbdi_util.h>

     void
     usb_detach_wait(device_ptr_t dv);

     void
     usb_detach_wakeup(device_ptr_t dv);

     const usb_descriptor_t *
     usb_find_desc(usbd_device_handle dev, int type, int subtype);

     usbd_status
     usbd_abort_default_pipe(usbd_device_handle dev);

     usbd_status
     usbd_abort_pipe(usbd_pipe_handle pipe);

     void *
     usbd_alloc_buffer(usbd_xfer_handle xfer, u_int32_t size);

     usbd_xfer_handle
     usbd_alloc_xfer(usbd_device_handle dev);

     usbd_status
     usbd_bulk_transfer(usbd_xfer_handle xfer, usbd_pipe_handle pipe,
             u_int16_t flags, u_int32_t timeout, void *buf, u_int32_t *size,
             char *lbl);

     usbd_status
     usbd_clear_endpoint_stall(usbd_pipe_handle pipe);

     usbd_status
     usbd_clear_endpoint_stall_async(usbd_pipe_handle);

     void
     usbd_clear_endpoint_toggle(usbd_pipe_handle pipe);

     usbd_status
     usbd_close_pipe(usbd_pipe_handle pipe);

     usbd_status
     usbd_device2interface_handle(usbd_device_handle dev, u_int8_t ifaceno,
             usbd_interface_handle *iface);

     void
     usbd_devinfo(usbd_device_handle dev, int showclass, char *cp);

     usbd_status
     usbd_do_request(usbd_device_handle dev, usb_device_request_t *req,
             void *data);

     usbd_status
     usbd_do_request_async(usbd_device_handle dev, usb_device_request_t *req,
             void *data);

     usbd_status
     usbd_do_request_flags(usbd_device_handle dev, usb_device_request_t *req,
             void *data, u_int16_t flags, int *actlen, u_int32_t timo);

     usbd_status
     usbd_do_request_flags_pipe(usbd_device_handle dev, usbd_pipe_handle pipe,
             usb_device_request_t *req, void *data, u_int16_t flags,
             int *actlen, u_int32_t timeout);

     void
     usbd_dopoll(usbd_interface_handle iface);

     usbd_status
     usbd_endpoint_count(usbd_interface_handle iface, u_int8_t *count);

     const char *
     usbd_errstr(usbd_status err);

     void
     usbd_fill_deviceinfo(usbd_device_handle dev, struct usb_device_info *di,
             int usedev);

     usb_endpoint_descriptor_t *
     usbd_find_edesc(usb_config_descriptor_t *cd, int ifaceidx, int altidx,
             int endptidx);

     usb_interface_descriptor_t *
     usbd_find_idesc(usb_config_descriptor_t *cd, int ifaceidx, int altidx);

     void
     usbd_free_buffer(usbd_xfer_handle xfer);

     usbd_status
     usbd_free_xfer(usbd_xfer_handle xfer);

     void *
     usbd_get_buffer(usbd_xfer_handle xfer);

     usbd_status
     usbd_get_config(usbd_device_handle dev, u_int8_t *conf);

     usbd_status
     usbd_get_config_desc(usbd_device_handle dev, int confidx,
             usb_config_descriptor_t *d);

     usbd_status
     usbd_get_config_desc_full(usbd_device_handle dev, int conf, void *d,
             int size);

     usb_config_descriptor_t *
     usbd_get_config_descriptor(usbd_device_handle dev);

     usb_device_descriptor_t *
     usbd_get_device_descriptor(usbd_device_handle dev);

     usb_endpoint_descriptor_t *
     usbd_get_endpoint_descriptor(usbd_interface_handle iface,
             u_int8_t address);

     int
     usbd_get_interface_altindex(usbd_interface_handle iface);

     usb_interface_descriptor_t *
     usbd_get_interface_descriptor(usbd_interface_handle iface);

     int
     usbd_get_no_alts(usb_config_descriptor_t *cdesc, int ifaceno);

     const struct usbd_quirks *
     usbd_get_quirks(usbd_device_handle dev);

     int
     usbd_get_speed(usbd_device_handle dev);

     usbd_status
     usbd_get_string(usbd_device_handle dev, int si, char *buf);

     usbd_status
     usbd_get_string_desc(usbd_device_handle dev, int sindex, int langid,
             usb_string_descriptor_t *sdesc, int *sizep);

     void
     usbd_get_xfer_status(usbd_xfer_handle xfer, usbd_private_handle *priv,
             void **buffer, u_int32_t *count, usbd_status *status);

     void
     usbd_interface2device_handle(usbd_interface_handle iface,
             usbd_device_handle *dev);

     usb_endpoint_descriptor_t *
     usbd_interface2endpoint_descriptor(usbd_interface_handle iface,
             u_int8_t index);

     usbd_status
     usbd_interface_count(usbd_device_handle dev, u_int8_t *count);

     usbd_status
     usbd_intr_transfer(usbd_xfer_handle xfer, usbd_pipe_handle pipe,
             u_int16_t flags, u_int32_t timeout, void *buf, u_int32_t *size,
             char *lbl);

     usbd_status
     usbd_open_pipe(usbd_interface_handle iface, u_int8_t address,
             u_int8_t flags, usbd_pipe_handle *pipe);

     usbd_status
     usbd_open_pipe_intr(usbd_interface_handle iface, u_int8_t address,
             u_int8_t flags, usbd_pipe_handle *pipe, usbd_private_handle priv,
             void *buffer, u_int32_t len, usbd_callback cb, int ival);

     usbd_device_handle
     usbd_pipe2device_handle(usbd_pipe_handle pipe);

     int
     usbd_ratecheck(struct timeval *last);

     usbd_status
     usbd_set_config_index(usbd_device_handle dev, int index, int msg);

     usbd_status
     usbd_set_config_no(usbd_device_handle dev, int no, int msg);

     usbd_status
     usbd_set_interface(usbd_interface_handle iface, int altidx);

     void
     usbd_set_polling(usbd_device_handle dev, int on);

     void
     usbd_setup_default_xfer(usbd_xfer_handle xfer, usbd_device_handle dev,
             usbd_private_handle priv, u_int32_t timeout,
             usb_device_request_t *req, void *buffer, u_int32_t length,
             u_int16_t flags, usbd_callback callback);

     void
     usbd_setup_isoc_xfer(usbd_xfer_handle xfer, usbd_pipe_handle pipe,
             usbd_private_handle priv, u_int16_t *frlengths,
             u_int32_t nframes, u_int16_t flags, usbd_callback callback);

     void
     usbd_setup_xfer(usbd_xfer_handle xfer, usbd_pipe_handle pipe,
             usbd_private_handle priv, void *buffer, u_int32_t length,
             u_int16_t flags, u_int32_t timeout, usbd_callback callback);

     usbd_status
     usbd_sync_transfer(usbd_xfer_handle xfer);

     usbd_status
     usbd_transfer(usbd_xfer_handle xfer);

DESCRIPTION

     The Universal Serial Bus (USB) driver programming interface provides USB
     peripheral drivers with a host controller independent API for controlling
     and communicating with USB peripherals.

     Typically, drivers will first use some combination of the functions
     usbd_set_config_no(), usbd_get_config_descriptor(), usbd_set_interface(),
     usbd_get_interface_descriptor(), usbd_device2interface_handle(),
     usbd_endpoint_count() and usbd_interface2endpoint_descriptor() to query
     the device’s properties and prepare it for use.  Drivers can then perform
     requests on the USB control pipe using usbd_do_request(), they can open
     pipes using the functions usbd_open_pipe() and usbd_open_pipe_intr(), and
     perform transfers over these pipes using usbd_alloc_xfer(),
     usbd_setup_xfer() and usbd_transfer().  Finally, the functions
     usbd_abort_pipe(), usbd_close_pipe() and usbd_free_xfer() are used to
     cancel outstanding transfers, close open pipes and deallocate transfer
     structures.

     The usbd_get_device_descriptor() function returns a pointer to the USB
     device descriptor for dev.  See USB Descriptors below for information
     about the USB device descriptor.

     The usbd_get_config_desc() function retrieves the specified configuration
     descriptor from the device.  The confidx parameter specifies the
     configuration descriptor index, which must be less than the
     bNumConfigurations value in the device descriptor.  The function
     usbd_get_config_desc_full() retrieves a full configuration descriptor,
     which has all related interface and endpoint descriptors appended to a
     normal configuration descriptor.  The parameter d should point to memory
     that is at least size bytes in length, and this should be at least as
     long as the wTotalLength value from the configuration descriptor.  See
     USB Descriptors below for information about the USB configuration
     descriptor.

     The usbd_get_config() function retrieves the current configuration number
     from the device, i.e. the bConfigurationValue value from the
     configuration that is active.  If the device is unconfigured then
     USB_UNCONFIG_NO is returned.  The current configuration can be changed by
     calling either usbd_set_config_index() or usbd_set_config_no().  The
     difference between these functions is that usbd_set_config_index()
     accepts a configuration index number that is less than the
     bNumConfigurations value from the device descriptor, whereas
     usbd_set_config_no() requires the bConfigurationValue value of the
     desired configuration to be provided instead.  To unconfigure the device,
     supply a configuration index of USB_UNCONFIG_INDEX to
     usbd_set_config_index(), or else specify a configuration number of
     USB_UNCONFIG_NO to usbd_set_config_no().

     The usbd_get_config_descriptor() function returns a pointer to an in-
     memory copy of the full configuration descriptor of the configuration
     that is currently active.  The returned pointer remains valid until the
     device configuration is changed using usbd_set_config_index() or
     usbd_set_config_no().  If the device is unconfigured then NULL is
     returned instead.

     The function usbd_interface_count() returns the number of interfaces
     available in the current device configuration.  The usbd_get_no_alts()
     function determines the number of alternate interfaces in a full
     configuration descriptor by counting the interface descriptors with
     bInterfaceNumber equal to ifaceno (the count includes alternate index
     zero).  The usbd_find_idesc() function locates an interface descriptor
     within a full configuration descriptor.  The ifaceidx parameter specifies
     the interface index number, which should be less than the number of
     interfaces in the configuration descriptor (i.e. the value returned by
     usbd_interface_count() or the bNumInterface field from the configuration
     descriptor).  An alternate interface can be specified using a non-zero
     altidx, which should be less than the value returned by
     usbd_get_no_alts().  The return value is a pointer to the requested
     interface descriptor within the full configuration descriptor, or NULL if
     the specified interface descriptor does not exist.  Note that the altidx
     parameter specifies the alternate setting by index number starting at
     zero; it is not the alternate setting number defined in the interface
     descriptor.

     The function usbd_find_edesc() locates an endpoint descriptor within a
     full configuration descriptor.  The ifaceidx and altidx parameters are
     the same as described for usbd_find_idesc(), and the endptidx parameter
     is an endpoint index number that should be less than the bNumEndpoints
     field in the interface descriptor.  The return value is a pointer to the
     requested endpoint descriptor within the full configuration descriptor,
     or NULL if the specified endpoint descriptor does not exist.  Note that
     the altidx and endptidx parameters are index numbers starting at zero;
     they are not the alternate setting and endpoint address defined in the
     descriptors.

     The usbd_get_speed() function returns the device speed.  This can be
     USB_SPEED_LOW, USB_SPEED_FULL or USB_SPEED_HIGH.

     USB devices optionally support string descriptors, which can be retrieved
     using the usbd_get_string() or usbd_get_string_desc() functions.  Device,
     configuration and interface descriptors reference strings by an index
     number that can be supplied to these functions.  The usbd_get_string()
     function should be used unless a non-default language is required.  It
     requires that buf points to a buffer of at least USB_MAX_STRING_LEN bytes
     in size.  The si parameter specified which string to retrieve.

     The usb_find_desc() function searches through the in-memory full
     configuration descriptor for the active configuration and finds the first
     descriptor that has a bDescriptorType equal to type, and if subtype is
     not equal to USBD_SUBTYPE_ANY, the descriptor must also have a
     bDescriptorSubtype equal to subtype.  If found, then a pointer to the
     descriptor is returned.  Otherwise, usb_find_desc() returns NULL.  The
     returned pointer is valid until the device configuration is changed using
     usbd_set_config_index() or usbd_set_config_no().

     The USB driver interface uses opaque interface handles to refer to
     configuration interfaces.  These handles remain valid until the device
     configuration is changed using usbd_set_config_index() or
     usbd_set_config_no().  The usbd_device2interface_handle() function
     retrieves an interface handle.  The ifaceno parameter is an interface
     index number starting at zero.  If the device is configured and the
     specified interface exists, then USBD_NORMAL_COMPLETION is returned and
     the interface handle is stored in *iface.  Otherwise an error code is
     returned and *iface is not changed.  The usbd_interface2device_handle()
     function retrieves the device handle from an interface handle.  This is
     just for convenience to save passing around the device handle as well as
     the interface handle.  The usbd_set_interface() function changes the
     alternate setting number for an interface to the alternate setting
     identified by the zero-based index number altidx.  This operation
     invalidates any existing endpoints on this interface and their
     descriptors.  The usbd_get_interface_altindex() function returns the
     current alternative setting index as was specified when calling
     usbd_set_interface().  The usbd_endpoint_count() function retrieves the
     number of endpoints associated with the specified interface.  The
     usbd_interface2endpoint_descriptor() function returns a pointer to an in-
     memory endpoint descriptor for the endpoint that has an index number of
     index.  This pointer remains valid until the configuration or alternate
     setting number are changed.  The function usbd_get_endpoint_descriptor()
     is like usbd_interface2endpoint_descriptor() but it accepts a
     bEndpointAddress address value instead of an index.

     The usbd_fill_deviceinfo() function fills out a usb_device_info structure
     with information about the device.  The vendor and product names come
     from the device itself, falling back to a table lookup or just providing
     the IDs in hexadecimal.  If usedev is zero then usbd_fill_deviceinfo()
     will not attempt to retrieve the vendor and product names from the
     device.  The usb_device_info structure is defined in #include
     <dev/usb/usb.h>
     as follows:

     struct usb_device_info {
             u_int8_t        udi_bus;
             u_int8_t        udi_addr;       /* device address */
             usb_event_cookie_t udi_cookie;
             char            udi_product[USB_MAX_STRING_LEN];
             char            udi_vendor[USB_MAX_STRING_LEN];
             char            udi_release[8];
             u_int16_t       udi_productNo;
             u_int16_t       udi_vendorNo;
             u_int16_t       udi_releaseNo;
             u_int8_t        udi_class;
             u_int8_t        udi_subclass;
             u_int8_t        udi_protocol;
             u_int8_t        udi_config;
             u_int8_t        udi_speed;
     #define USB_SPEED_LOW  1
     #define USB_SPEED_FULL 2
     #define USB_SPEED_HIGH 3
             int             udi_power;      /* power consumption in mA */
             int             udi_nports;
             char            udi_devnames[USB_MAX_DEVNAMES][USB_MAX_DEVNAMELEN];
             /* hub only: addresses of devices on ports */
             u_int8_t        udi_ports[16];
     #define USB_PORT_ENABLED 0xff
     #define USB_PORT_SUSPENDED 0xfe
     #define USB_PORT_POWERED 0xfd
     }

     The usbd_devinfo() function generates a string description of the USB
     device.  The cp argument should point to a 1024-byte buffer (XXX the
     maximum length is approximately 320 chars, but there is no sanity
     checking and everything uses 1024-character buffers).  Device class
     information is included if the showclass parameter is non-zero.

     The usbd_get_quirks() function returns information from a table of
     devices that require special workarounds in order to function correctly.
     The returned structure is defined in #include <dev/usb/usb_quirks.h>
     as follows:

     struct usbd_quirks {
             u_int32_t uq_flags;     /* Device problems */
     };

     See #include <dev/usb/usb_quirks.h>
     for a list of all currently defined quirks.

     USB control requests are performed via usb_device_request_t structures,
     defined in #include <dev/usb/usb.h>
     as follows:

     typedef struct {
             uByte           bmRequestType;
             uByte           bRequest;
             uWord           wValue;
             uWord           wIndex;
             uWord           wLength;
     } UPACKED usb_device_request_t;

     The usbd_do_request() function performs a single request synchronously.
     The req parameter should point to a properly initialized
     usb_device_request_t, and when the wLength field is non-zero, data should
     point at a buffer that is at least wLength bytes in length.  The request
     timeout is set to 5 seconds, so the operation will fail with USBD_TIMEOUT
     if the device does not respond within that time.  The
     usbd_do_request_async() function is like usbd_do_request(), but it does
     not wait for the request to complete before returning.  This routine does
     not block so it can be used from contexts where sleeping is not allowed.
     Note that there is no notification mechanism to report when the operation
     completed nor is there a way to determine whether the request succeeded,
     so this function is of limited use.  See usbd_setup_default_xfer() and
     usbd_transfer() for a way to invoke an asynchronous callback upon
     completion of a control request.  The usbd_do_request_flags() function is
     like usbd_do_request(), but additional flags can be specified, the
     timeout is configurable, and the actual number of bytes transferred is
     made available to the caller.  The usbd_do_request_flags_pipe() function
     uses a specified pipe instead of the default pipe.

     The function usbd_open_pipe() creates a pipe connected to a specified
     endpoint on a specified interface.  The parameter address should be the
     bEndpointAddress value from one of this interface’s endpoint descriptors.
     If flags contains USBD_EXCLUSIVE_USE then the operation will only succeed
     if there are no open pipes already connected to the specified endpoint.
     The usbd_open_pipe_intr() function creates an interrupt pipe connected to
     the specified endpoint.  The parameter address should be the
     bEndpointAddress value from one of this interface’s endpoint descriptors.
     The flags parameter is passed to usbd_setup_xfer().  The buffer and len
     parameters define a buffer that is to be used for the interrupt
     transfers.  The callback to be invoked each time a transfer completes is
     specified by cb, and priv is an argument to be passed to the callback
     function.  The ival parameter specifies the maximum acceptable interval
     between transfers; in practice the transfers may occur more frequently.
     The function usbd_pipe2device_handle() returns the device associated with
     the specified pipe.

     The usbd_abort_pipe() function aborts all active or waiting transfers on
     the specified pipe.  Each transfer is aborted with a USBD_CANCELLED
     status; callback routines must detect this error code to ensure that they
     do not attempt to initiate a new transfer in response to one being
     aborted.  This routine blocks while it is waiting for the hardware to
     complete processing of aborted transfers, so it is only safe to call it
     in contexts where sleeping is allowed.  The function
     usbd_abort_default_pipe() aborts all active or waiting transfers on the
     default pipe.  Like usbd_abort_pipe(), it blocks waiting for the hardware
     processing to complete.

     When a pipe has no active or waiting transfers, the pipe may be closed
     using the usbd_close_pipe() function.  Once a pipe is closed, its pipe
     handle becomes invalid and may no longer be used.

     USB transfer handles are allocated using the function usbd_alloc_xfer()
     and may be freed using usbd_free_xfer().

     The function usbd_setup_xfer() initializes a transfer handle with the
     details of a transfer to or from a USB device.  The xfer parameter
     specifies the transfer handle to initialize, pipe specifies the pipe on
     which the transfer is to take place, and priv is an argument that will be
     passed to callback function.  The arguments buffer and length define the
     data buffer for the transfer.  If length is zero then the buffer may be
     NULL.  The flags parameter may contain the following flags:

     USBD_NO_COPY           This is used in association with
                            usbd_alloc_buffer() and usbd_free_buffer() to use
                            a dedicated DMA-capable buffer for the transfer.

     USBD_SYNCHRONOUS       Wait for the transfer to compete in
                            usbd_transfer().

     USBD_SHORT_XFER_OK     Permit transfers shorter than the requested data
                            length.

     USBD_FORCE_SHORT_XFER  Force a short transfer at the end of a write
                            operation to let the device know that the transfer
                            has ended.

     The timeout parameter specifies a timeout for the transfer in
     milliseconds.  A value of USBD_NO_TIMEOUT indicates that no timeout
     should be configured.  The parameter callback specifies the function to
     call when the transfer completes.  Note that usbd_setup_xfer() does not
     actually initiate the transfer.  The usbd_setup_default_xfer()
     initializes a control transfer for the default pipe.  The req parameter
     should point at a completed usb_device_request_t structure.  The function
     usbd_setup_isoc_xfer initializes a transfer for an isochronous pipe.

     The function usbd_transfer() initiates a transfer.  Normally it returns
     USBD_IN_PROGRESS to indicate that the transfer has been queued.  If the
     USB stack is operating in polling mode, or if the transfer is
     synchronous, then USBD_NORMAL_COMPLETION may be returned.  Other return
     values indicate that the transfer could not be initiated due to an error.
     The usbd_sync_transfer() function executes a transfer synchronously.  It
     will sleep waiting for the transfer to complete and then return the
     transfer status.  Note that if the transfer has a callback routine, this
     will be invoked before usbd_sync_transfer() returns.

     The usbd_intr_transfer() and usbd_bulk_transfer() functions set up a
     transfer and wait synchronously for it to complete but they allows
     signals to interrupt the wait.  They returns USBD_INTERRUPTED if the
     transfer was interrupted by a signal.  XXX these two functions are
     identical apart from their names.

     The function usbd_get_xfer_status() retrieves various information from a
     completed transfer.  If the priv parameter is not NULL then the callback
     private argument is stored in *priv.  If buffer is not NULL then the
     transfer buffer pointer is stored in *buffer.  The actual number of bytes
     transferred is stored in *count if count is not NULL. Finally, the
     transfer status is stored in *status if status is not NULL.

     The usbd_clear_endpoint_stall() function clears an endpoint stall
     condition synchronously, i.e. it sleeps waiting for the stall clear
     request to complete.  The function usbd_clear_endpoint_stall_async()
     performs the same function asynchronously, but it provides no way to
     determine when the request completed, or whether it was successful.  The
     usbd_clear_endpoint_toggle() function instructs the host controller
     driver to reset the toggle bit on a pipe.  This is used when manually
     clearing an endpoint stall using a control pipe request, in order to
     ensure that the host controller driver and the USB device restart with
     the same toggle value.

     Normally the USB subsystem maps and copies data to and from DMA-capable
     memory each time a transfer is performed.  The function
     usbd_alloc_buffer() allocates a permanent DMA-capable buffer associated
     with the transfer to avoid this overhead.  The return value is the
     virtual address of the buffer.  Any time that usbd_setup_xfer() is called
     on the transfer with the USBD_NO_COPY flag enabled, the allocated buffer
     will be used directly and the buffer argument passed to usbd_setup_xfer()
     will be ignored.  The usbd_get_buffer() function returns a pointer to the
     virtual address of a buffer previously allocated by usbd_alloc_buffer().
     Finally, usbd_free_buffer() deallocates the buffer.

     The usbd_errstr() function converts a status code into a string for
     display.

     The function usbd_set_polling() enables or disables polling mode.  In
     polling mode, all operations will busy-wait for the device to respond, so
     its use is effectively limited to boot time and kernel debuggers.  It is
     important to match up calls that enable and disable polling mode, because
     the implementation just increments a polling reference count when on is
     non-zero and decrements it when on is zero.  The usbd_dopoll() causes the
     host controller driver to poll for any activity.  This should only be
     used when polling mode is enabled.

     The usbd_ratecheck() function is used to limit the rate at which error
     messages are printed to approximately once per second.  The last argument
     should point at a persistent struct timeval.  A value of 1 will be
     returned if a message should be printed, but if usbd_ratecheck() has
     already been called with the same struct timeval parameter in the last
     second then 0 is returned and the error message should be suppressed.

     The functions usb_detach_wait() and usb_detach_wakeup() are used to wait
     for references to drain before completing the detachment of a device.
     The usb_detach_wait() function will wait up to 60 seconds to receive a
     signal from usb_detach_wait().

   USB Descriptors
     The USB specification defines a number of standard descriptors by which
     USB devices report their attributes.  These descriptors are fixed-format
     structures that all USB devices make available through USB control pipe
     requests.

     Every USB device has exactly one USB device descriptor.  The USB
     subsystem retrieves this automatically when a device is attached, and a
     copy of the descriptor is kept in memory.  The
     usbd_get_device_descriptor() function returns a pointer to the
     descriptor.  The device descriptor structure is defined in #include
     <dev/usb/usb.h>
     as follows:

     typedef struct {
             uByte           bLength;
             uByte           bDescriptorType;
             uWord           bcdUSB;
     #define UD_USB_2_0              0x0200
     #define UD_IS_USB2(d) (UGETW((d)->bcdUSB) >= UD_USB_2_0)
             uByte           bDeviceClass;
             uByte           bDeviceSubClass;
             uByte           bDeviceProtocol;
             uByte           bMaxPacketSize;
             /* The fields below are not part of the initial descriptor. */
             uWord           idVendor;
             uWord           idProduct;
             uWord           bcdDevice;
             uByte           iManufacturer;
             uByte           iProduct;
             uByte           iSerialNumber;
             uByte           bNumConfigurations;
     } UPACKED usb_device_descriptor_t;
     #define USB_DEVICE_DESCRIPTOR_SIZE 18

     USB devices have at least one configuration descriptor.  The
     bNumConfigurations field of the device descriptor specifies the number of
     configuration descriptors that a device supports.  The
     usbd_get_config_desc() function retrieves a particular configuration
     descriptor from the device and the usbd_get_config_desc_full() function
     retrieves a full wTotalLength length configuration descriptor, which
     includes all related interface and endpoint descriptors.  Only one
     configuration may be active at a time.  The usbd_set_config_index()
     function activates a specified configuration.  The configuration
     descriptor structure is defined in #include <dev/usb/usb.h>
     as follows:

     typedef struct {
             uByte           bLength;
             uByte           bDescriptorType;
             uWord           wTotalLength;
             uByte           bNumInterface;
             uByte           bConfigurationValue;
             uByte           iConfiguration;
             uByte           bmAttributes;
     #define UC_BUS_POWERED          0x80
     #define UC_SELF_POWERED         0x40
     #define UC_REMOTE_WAKEUP        0x20
             uByte           bMaxPower; /* max current in 2 mA units */
     #define UC_POWER_FACTOR 2
     } UPACKED usb_config_descriptor_t;
     #define USB_CONFIG_DESCRIPTOR_SIZE 9

     Each device configuration provides one or more interfaces.  The
     bNumInterface field of the configuration descriptor specifies the number
     of interfaces associated with a device configuration.  Interfaces are
     described by an interface descriptor, which is defined in #include
     <dev/usb/usb.h>
     as follows:

     typedef struct {
             uByte           bLength;
             uByte           bDescriptorType;
             uByte           bInterfaceNumber;
             uByte           bAlternateSetting;
             uByte           bNumEndpoints;
             uByte           bInterfaceClass;
             uByte           bInterfaceSubClass;
             uByte           bInterfaceProtocol;
             uByte           iInterface;
     } UPACKED usb_interface_descriptor_t;
     #define USB_INTERFACE_DESCRIPTOR_SIZE 9

     Configurations may also have alternate interfaces with the same
     bInterfaceNumber but different bAlternateSetting values.  These alternate
     interface settings may be selected by passing a non-zero altidx parameter
     to usbd_set_interface().

     Interfaces have zero or more endpoints, and each endpoint has an endpoint
     descriptor.  Note that endpoint zero, which is always present, does not
     have an endpoint descriptor, and it is never included in the
     bNumEndpoints count of endpoints.  The endpoint descriptor is defined in
     #include <dev/usb/usb.h>
     as follows:

     typedef struct {
             uByte           bLength;
             uByte           bDescriptorType;
             uByte           bEndpointAddress;
     #define UE_GET_DIR(a)   ((a) & 0x80)
     #define UE_SET_DIR(a,d) ((a) | (((d)&1) << 7))
     #define UE_DIR_IN       0x80
     #define UE_DIR_OUT      0x00
     #define UE_ADDR         0x0f
     #define UE_GET_ADDR(a)  ((a) & UE_ADDR)
             uByte           bmAttributes;
     #define UE_XFERTYPE     0x03
     #define  UE_CONTROL     0x00
     #define  UE_ISOCHRONOUS 0x01
     #define  UE_BULK        0x02
     #define  UE_INTERRUPT   0x03
     #define UE_GET_XFERTYPE(a)      ((a) & UE_XFERTYPE)
     #define UE_ISO_TYPE     0x0c
     #define  UE_ISO_ASYNC   0x04
     #define  UE_ISO_ADAPT   0x08
     #define  UE_ISO_SYNC    0x0c
     #define UE_GET_ISO_TYPE(a)      ((a) & UE_ISO_TYPE)
             uWord           wMaxPacketSize;
             uByte           bInterval;
     } UPACKED usb_endpoint_descriptor_t;
     #define USB_ENDPOINT_DESCRIPTOR_SIZE 7

RETURN VALUES

     Many functions return a usbd_status type to indicate the outcome of the
     operation.  If the operation completed successfully then
     USBD_NORMAL_COMPLETION is returned.  Operations that have been started
     but not yet completed will return USBD_IN_PROGRESS.  Other errors usually
     indicate a problem.  Error codes can be converted to strings using
     usbd_errstr().

ERRORS

     [USBD_PENDING_REQUESTS]
                            A pipe could not be closed because there are
                            active requests.

     [USBD_NOT_STARTED]     The transfer has not yet been started.

     [USBD_INVAL]           An invalid value was supplied.

     [USBD_NOMEM]           An attempt to allocate memory failed.

     [USBD_CANCELLED]       The transfer was aborted.

     [USBD_BAD_ADDRESS]     The specified endpoint address was not found.

     [USBD_IN_USE]          The endpoint is already in use, or the
                            configuration cannot be changed because some of
                            its endpoints are in use.

     [USBD_NO_ADDR]         No free USB devices addresses were found to assign
                            to the device.

     [USBD_SET_ADDR_FAILED]
                            The device address could not be set.

     [USBD_NO_POWER]        Insufficient power was available for the device.

     [USBD_TOO_DEEP]        Too many levels of chained hubs were found.

     [USBD_IOERROR]         There was an error communicating with the device.

     [USBD_NOT_CONFIGURED]  An operation that requires an active configuration
                            was attempted while the device was in an
                            unconfigured state.

     [USBD_TIMEOUT]         A transfer timed out.

     [USBD_SHORT_XFER]      A transfer that disallowed short data lengths
                            completed with less than the requested length
                            transferred.

     [USBD_STALLED]         A transfer failed because the pipe is stalled.

     [USBD_INTERRUPTED]     An interruptible operation caught a signal.

SEE ALSO

     usb(4)

HISTORY

     The USB driver interface first appeared in FreeBSD 3.0.

AUTHORS

     The USB driver was written by Lennart Augustsson for the NetBSD project.

     This manual page was written by Ian Dowse 〈iedowse@FreeBSD.org〉.