usb_get_descriptor(9)
NAME
usb_get_descriptor - issues a generic GET_DESCRIPTOR request
SYNOPSIS
int usb_get_descriptor(struct usb_device * dev, unsigned char type,
unsigned char index, void * buf, int size);
ARGUMENTS
- dev
- the device whose descriptor is being retrieved
- type
- the descriptor type (USB_DT_*)
- index
- the number of the descriptor
- buf
- where to put the descriptor
- size
- how big is "buf"?
CONTEXT
!in_interrupt ()
DESCRIPTION
Gets a USB descriptor. Convenience functions exist to simplify getting
some types of descriptors. Use usb_get_string or usb_string for
USB_DT_STRING. Device (USB_DT_DEVICE) and configuration descriptors
(USB_DT_CONFIG) are part of the device structure. In addition to a
number of USB-standard descriptors, some devices also use
class-specific or vendor-specific descriptors.
This call is synchronous, and may not be used in an interrupt context.
Returns the number of bytes received on success, or else the status
code returned by the underlying usb_control_msg call.