m68k: use the coherent DMA code for coldfire without data cache
Coldfire cores configured without a data cache are DMA coherent and
should thus simply use the simple coherent version of dma-direct.
Introduce a new COLDFIRE_COHERENT_DMA Kconfig symbol as a convenient
short hand for such configurations, and a M68K_NONCOHERENT_DMA symbol
for all cases where we need to build non-coherent DMA infrastructure
to simplify the Kconfig and code conditionals.
Not building the non-coherent DMA code slightly reduces the code
size for such configurations.
Numers for m5249evb_defconfig below:
text data bss dec hex filename
2896158 401052 65392
3362602 334f2a vmlinux.before
2895166 400988 65392
3361546 334b0a vmlinux.after
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Greg Ungerer <gerg@linux-m68k.org>