USBD_ENUMERATE_DEVICE
Purpose
Gets a list of USB logical devices (excluding hubs) that are connected to a host controller.
Syntax
int ioctl (file, USBD_ENUMERATE_DEVICE, arg)
Parameters
| Item | Description |
|---|---|
| file | File descriptor that is obtained when the USBD special file was opened. |
| arg | Address of the USBENUM structure
that is aligned on a 4-byte boundary. |
Description
This ioctl operation returns
a description of each logical USB device that is connected to the
specified host controllers without any hubs. The description is returned
in the form of a usb_device_t structure. The array
of returned structures is encapsulated within a USBENUM structure
whose length is specified by the caller. When this function is started,
the devno and buffSize fields within
the USBENUM structure must be initialized. The devno field
must contain the 32-bit devno value of the host controller
to be enumerated while the buffSize field must indicate
the number of bytes that are available to buffer the returned array
of usb_device_t structures. If the area is too small,
the number of returned structures is truncated to fit the available
space. The caller can detect this condition by noting that the number
of returned usb_device_t structures is less than
the number of discovered logical devices.
Execution environment
This function can be called from the user process environment only.
Return values
| Value | Description |
|---|---|
| 0 | Success. |
| -1 | Failure. Check the errno value for specific failure causes. |