StreamSPI: add empty files

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: implement minimal configuration to register StreamSPI

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: move class into SPI library

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: fix headers

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: do not use default error numbers

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: raise interrupt

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: add SPI interrupt handler

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: add empty Stream methods

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: add head and tail buffer index

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: add buffer_size attribute

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: handle ring buffer RX and TX

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: use pointer instead of index

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: add empty Print methods

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: move preinstance object at top

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: fix instance creation

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: description of head an tail pointers

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: implementation of available method

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: fix store ring control

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: implements peek method

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>
StreamSPI: implements read method

Signed-off-by: Federico Vaga <federico.vaga@gmail.com>