dma: allow dma_get_cache_alignment() to be overridden by the arch code

On arm64, ARCH_DMA_MINALIGN is larger than most cache line size
configurations deployed.  Allow an architecture to override
dma_get_cache_alignment() in order to return a run-time probed value (e.g.
cache_line_size()).

Link: https://lkml.kernel.org/r/20230612153201.554742-3-catalin.marinas@arm.comSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Isaac J. Manjarres <isaacmanjarres@google.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jerry Snitselaar <jsnitsel@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/dma-mapping.h

@@ -544,6 +544,7 @@ static inline int dma_set_min_align_mask(struct device *dev,
 	return 0;
 }
 
+#ifndef dma_get_cache_alignment
 static inline int dma_get_cache_alignment(void)
 {
 #ifdef ARCH_HAS_DMA_MINALIGN
@@ -551,6 +552,7 @@ static inline int dma_get_cache_alignment(void)
 #endif
 	return 1;
 }
+#endif
 
 static inline void *dmam_alloc_coherent(struct device *dev, size_t size,
 		dma_addr_t *dma_handle, gfp_t gfp)