1. I have a slave device running on SPI which needs to communicate with MCU.
2. I need to set MCU SPI mode.
3. Which SPI mode is this. I think its SPI mode 1.
I don't think this is SPI at all, if you want to use common microcontrollers to interface with it. It seems as if you clock in 18 bits on SDI, and then the output bits begin--that is a long way from standard. Normally you'd send and receive 8 bits simultaneously, but maybe there's a processor somewhere that has "programmable SPI" that lets you select everything. If you're bit-banging it, then you just follow the diagram and it is what it is, SPI or something unique.
Oh yeah, it's a 24-bit data and address frame; I have to do something about this astigmatism. If the number of bits is a multiple of 8, then conventional SPI should work--just be sure you know which bytes are being sent. Order is high bit first. You can look up the mode here: http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus#Clock_polarity_and_phase