Re: [Qemu-devel] [PATCH V4 0/5] Ehnahced SSI bus support + M25P80 SPI flash + Xilinx SPI controller

[Paul Brook <paul@codesourcery.com>]

> Patch 1 Enhances SSI bus support to properly support multiple attached
> devices. An api is provided for SSI/SPI masters to select a particular
> device attached to the bus.
> 
> Patch 2 is a device model for the m25p80 style SPI flash chip.
> 
> Patch 3 is  the Xilinx XPS SPI contoller. Its a sysbus device that
> instantiates a ssi bus, and interfaces the two (as per the controllers
> functionality)
> 
> Patch 4 instantiates the XPS SPI controller in the petalogix ML605
> reference platform and connects two m25p80s to it.
> 
> Patch 5 updates the stellaris machine model to use the multi slave SSI
> support

I'm still not convinced modelling this as a multipoint bus is a good idea.  If 
nothing else you've failed to model the case where multiple slaves are 
selected simultanously.  Given the chip selects are actual wires, not part of 
the bus itself, I think multiple point-point busses are a better fit.

For the stellaris device we still have the synthetic mux device and 
intermediate bus.


Paul