[UrJTAG-dev] MPC5200 bus driver

[Daniel Burr]

Hi everybody,

The MPC5200 bus driver currently supports only two specific configurations:

* Non-Muxed 24b address, 8b data bus
* Muxed 25b address, 16b data bus

For my purposes I needed to use a Non-Muxed 26b address with a 16b data
bus, i.e. what is referred to as "Large Flash Mode" in the MPC5200 User
Manual. Therefore I have modified the bus driver and introduced 2 new
arguments:

* ALEN: Address length in bits
* DLEN: Data length in bits

This should allow the bus driver to support all 8 non-muxed
configurations specified in Table 9-2 as well as the 12 muxed
configurations specified in Table 9-4. The behaviour defaults to Legacy
Mode (which is what is used for the two configurations which are
currently supported) but the pins corresponding to Large Flash Mode or
MOST Graphics Mode will be used when the appropriate combination of ALEN
and DLEN are enabled:

* ALEN=26,DLEN=8 or ALEN=26,DLEN=16 => sets address pins as per Large
Flash Mode
* ALEN=24,DLEN=32 => sets address pins as per MOST Graphics Mode

Note that enabling the MUX option will no longer automatically change
the configuration to 25b/16b as is done currently. However, it is
trivial to restore the current behaviour by specifying the appropriate
bus arguments, i.e. `initbus mpc5200 MUX ALEN=25 DLEN=16`.

I have only tested the non-Muxed Legacy and Large Flash Modes since that
is all I have access to. I am relatively confident that these changes
will not break the support for MUXed mode, but I am unable to verify
this for myself. Would anyone on this list be able to run a quick test
and/or consider committing this patch?

Thanks,
Daniel Burr