m68k: Use the generic dma coherent remap allocator

This switches m68k to using common code for the DMA allocations,
including potential use of the CMA allocator if configured.
Also add a comment where the existing behavior seems to be lacking.

Switching to the generic code enables DMA allocations from atomic
context, which is required by the DMA API documentation, and also
adds various other minor features drivers start relying upon.  It
also makes sure we have a tested code base for all architectures
that require uncached pte bits for coherent DMA allocations.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

1 files changed, 8 insertions, 48 deletions

diff --git a/arch/m68k/kernel/dma.c b/arch/m68k/kernel/dma.c
index b4aa853051bd..e7bf355589e7 100644
--- a/arch/m68k/kernel/dma.c
+++ b/arch/m68k/kernel/dma.c
@@ -18,57 +18,17 @@
 #include <asm/pgalloc.h>
 
 #if defined(CONFIG_MMU) && !defined(CONFIG_COLDFIRE)
-
-void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
-		gfp_t flag, unsigned long attrs)
+pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
+		unsigned long attrs)
 {
-	struct page *page, **map;
-	pgprot_t pgprot;
-	void *addr;
-	int i, order;
-
-	pr_debug("dma_alloc_coherent: %d,%x\n", size, flag);
-
-	size = PAGE_ALIGN(size);
-	order = get_order(size);
-
-	page = alloc_pages(flag | __GFP_ZERO, order);
-	if (!page)
-		return NULL;
-
-	*handle = page_to_phys(page);
-	map = kmalloc(sizeof(struct page *) << order, flag & ~__GFP_DMA);
-	if (!map) {
-		__free_pages(page, order);
-		return NULL;
+	if (CPU_IS_040_OR_060) {
+		pgprot_val(prot) &= ~_PAGE_CACHE040;
+		pgprot_val(prot) |= _PAGE_GLOBAL040 | _PAGE_NOCACHE_S;
+	} else {
+		pgprot_val(prot) |= _PAGE_NOCACHE030;
 	}
-	split_page(page, order);
-
-	order = 1 << order;
-	size >>= PAGE_SHIFT;
-	map[0] = page;
-	for (i = 1; i < size; i++)
-		map[i] = page + i;
-	for (; i < order; i++)
-		__free_page(page + i);
-	pgprot = __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_DIRTY);
-	if (CPU_IS_040_OR_060)
-		pgprot_val(pgprot) |= _PAGE_GLOBAL040 | _PAGE_NOCACHE_S;
-	else
-		pgprot_val(pgprot) |= _PAGE_NOCACHE030;
-	addr = vmap(map, size, VM_MAP, pgprot);
-	kfree(map);
-
-	return addr;
+	return prot;
 }
-
-void arch_dma_free(struct device *dev, size_t size, void *addr,
-		dma_addr_t handle, unsigned long attrs)
-{
-	pr_debug("dma_free_coherent: %p, %x\n", addr, handle);
-	vfree(addr);
-}
-
 #else
 
 #include <asm/cacheflush.h>