dma-direct: make uncached_kernel_address more general

Rename the symbol to arch_dma_set_uncached, and pass a size to it as
well as allow an error return.  That will allow reusing this hook for
in-place pagetable remapping.

As the in-place remap doesn't always require an explicit cache flush,
also detangle ARCH_HAS_DMA_PREP_COHERENT from ARCH_HAS_DMA_SET_UNCACHED.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>

2 files changed, 3 insertions, 2 deletions

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 797d7f1ad5fe..489185db501e 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1187,8 +1187,9 @@ config DMA_NONCOHERENT
 	# significant advantages.
 	#
 	select ARCH_HAS_DMA_WRITE_COMBINE
+	select ARCH_HAS_DMA_PREP_COHERENT
 	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
-	select ARCH_HAS_UNCACHED_SEGMENT
+	select ARCH_HAS_DMA_SET_UNCACHED
 	select DMA_NONCOHERENT_MMAP
 	select DMA_NONCOHERENT_CACHE_SYNC
 	select NEED_DMA_MAP_STATE
diff --git a/arch/mips/mm/dma-noncoherent.c b/arch/mips/mm/dma-noncoherent.c
index 77dce28ad0a0..fcea92d95d86 100644
--- a/arch/mips/mm/dma-noncoherent.c
+++ b/arch/mips/mm/dma-noncoherent.c
@@ -49,7 +49,7 @@ void arch_dma_prep_coherent(struct page *page, size_t size)
 	dma_cache_wback_inv((unsigned long)page_address(page), size);
 }
 
-void *uncached_kernel_address(void *addr)
+void *arch_dma_set_uncached(void *addr, size_t size)
 {
 	return (void *)(__pa(addr) + UNCAC_BASE);
 }