Is 5-wire SPI possible?

Does anyone know if the Debian BBB is able to communicate with this 5-wire device? What’s a good approach?

SPI communication typically involves 4 wires: select, clock, MOSI, MISO. Nordic Semiconductors makes a bluetooth chip nRF8001 that adds another wire into the mix RDYN. After chip select, the master is not supposed to clock out data until the slaves sets RDYN low. Also the slave uses RDYN to tell the master data is available. I think some articles I’ve read call this flow control, others call it handshaking, and others call it 5 wire, perhaps they’re one in the same. But it’s not clear that the 5-wire variant some mention behave identically to the 5-wires implemented by Nordic.

In particular I’m obsessed with understanding the following, and any additional references or pointers would be appreciated:

  1. In DTS file discussions, I’ve seen references specifying interrupts. Is this another type, same type or altogether different type of 5-wire.

  2. Can the McSPI hardware actually handle this type of communication? It would have to keep CS active while it waits for an interrupt from the RDYN line – which means it would have to block other interrupts from other devices on the same chain, plus there’d have to be some timeout to prevent infinite blocking if RDYN goes sour.

  3. Is the bit banging SPI driver incorporated into the the BBB kernel? Any sample dts files out there?

Thanks in advance,