Belkin F8E211 Guida Utente Scaricare il pdf (Pagina 37)

attach()

Attach to a USB device

Synopsis:

#include <sys/usbdi.h>

int usbd_attach( struct usbd_connection *connection,

usbd_device_instance_t *instance,

size_t extra,

struct usbd_device **device );

Arguments:

connection An opaque handle that identiﬁes the USB stack (from usbd

connect()).

instance Describes which device you wish to attach to.

extra The size of additional memory you’d like allocated with the device.

You can use usbd

device

extra() later to get a pointer to this

additional memory. Typically, the class driver would store various

status/conﬁg/device-speciﬁc details in here (if needed).

device An opaque handle used to identify the device in later calls.

Library:

libusbdi

Description:

You use the usbd

attach() function to attach to a USB device. Typically, you do this

out of the insertion callback (made when the device matched your ﬁlter), which will

give you the connection and instance parameters involved. The insertion callback is

prototyped as follows:

void (*insertion)(struct usbd_connection *, usbd_device_instance_t *instance)

The usbd_device_instance_t structure looks like this:

typedef struct usbd_device_instance {

_uint8 path;

_uint8 devno;

_uint16 generation;

usbd_device_ident_t ident;

_uint32 config;

_uint32 iface;

_uint32 alternate;

} usbd_device_instance_t;

September 10, 2007 Chapter 4 • USB Library Reference 23

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Belkin F8E211 Guida Utente Pagina 37