I'm working on a u-boot port to custom hardware based on the Lite5200B
board, with a MPC5200 processor. u-boot is working great (can boot from 16-bit
flash, SDRAM is working and I can boot linux!) but now I'm working through some
MMU configuration issues, and had a few general questions:
1. Does u-boot/linux make any assumptions about how particular BAT registers
are used? For example, we're not using PCI, and I was going to use those BAT
registers to cover some memory-mapped peripheral I/O space (ex: icecube.c,
DBAT3 and 4 are used for PCI, so I would use them instead for our I/O ranges.)
2. Do you need a separate BAT register for each memory mapped I/O space? We
have 4 chip selects, but could I arrange the chip selects to use a contiguous
range and presumably cover that with a single BAT register?
3. Would I need separate BAT registers for 8-bit vs. 16-bit devices?
Also, maybe slightly off topic, but has anyone had problems using 8-bit
peripherals on the MPC52000 in large flash mode? I'm seeing some odd behavior
that looks as though the internal PPC bus thinks 8-bit data is on bits 8-15 and
only ever reads/writes zeros, and the external data lines (d0-d7) show correct
data for reads, and only shows correct data for odd-address writes.
Thanks,
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