Recently I’ve worked on Scratchpad allocation. Scratchpad buffers are PAGESIZE blocks of system memory which the xHCI uses to store its internal state. xHCI can request 0 to 1024 buffers. Number of buffers required is given in the HCSPARAMS1 register. Each buffer is a PAGESIZE block aligned to PAGESIZE boundary. Scratchpad buffer array is an array which contains addresses of the scratchpad buffers. Its size is equal to the number of maximum scratchpad buffers required by the hardware.
