spi: dw: Add Baikal-T1 SPI Controller bindings

These controllers are based on the DW APB SSI IP-core and embedded into
the SoC, so two of them are equipped with IRQ, DMA, 64 words FIFOs and 4
native CS, while another one as being utilized by the Baikal-T1 System
Boot Controller has got a very limited resources: no IRQ, no DMA, only a
single native chip-select and just 8 bytes Tx/Rx FIFOs available. That's
why we have to mark the IRQ to be optional for the later interface.

The SPI controller embedded into the Baikal-T1 System Boot Controller can
be also used to directly access an external SPI flash by means of a
dedicated FSM. The corresponding MMIO region availability is switchable by
the embedded multiplexor, which phandle can be specified in the dts node.

* We added a new example to test out the non-standard Baikal-T1 System
Boot SPI Controller DT binding.

Co-developed-by: Ramil Zaripov <[email protected]>
Signed-off-by: Ramil Zaripov <[email protected]>
Signed-off-by: Serge Semin <[email protected]>
Reviewed-by: Rob Herring <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>

0 files changed, 0 insertions, 0 deletions