Download Bootstrap Yourself with Linux-USB Stack

Bootstrap Linux USB HCD
Some other key interface functions act like an HCDI between the HCD and the
usbcore framework along with the preceding callback functions.
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int usb_hcd_submit_urb(struct urb *urb, gfp_t mem_flags)
The transfer of USB data to and from the host is using the USB Request
Block (URB) data structure. This acts as an interface for the usb_submit_urb
method and provides access to the host controller through the urb_enqueue
callback.
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int usb_hcd_unlink_urb(struct urb *urb, int status)
This interface function allows the usbcore to cancel a URB submission
and unlink it from the URB queue. usb_unlink_urb invokes this interface
function to abort and cancel URB submissions.
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void usb_hcd_giveback_urb(struct usb_hcd *hcd, struct urb *urb,int
status);
This interface function returns the information collected for the URB
request to the driver. This interface hands over the URB from the HCD
to the device driver using the usb_hcd_giveback_urb interface function.
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struct usb_hcd *usb_create_hcd(const struct hc_driver *driver,struct
device *dev, const char *bus_name)
This interface function allocates and initializes a struct usb_hcd data
structure and returns NULL if memory is unavailable. The host drivers use
this interface function on a successful probe to allocate a struct usb_hcd
data structure.
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int usb_add_hcd(struct usb_hcd *hcd,unsigned int irqnum, unsigned long
irqflags)
This interface function initializes struct usb_hcd with necessary resources
such as memory and interrupts and registers the bus. The function calls
the HCD’s reset and start routines.
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void usb_remove_hcd(struct usb_hcd *hcd)
This interface function is invoked during the shutdown process. It
releases resources allocated during the usb_add_hcd function and then
invokes the HCD driver’s stop function.
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