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>

2 files changed, 10 insertions, 48 deletions

diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 218e037ef901..3a52bf46e043 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -3,10 +3,12 @@ config M68K
         bool
         default y
         select ARCH_32BIT_OFF_T
+        select ARCH_HAS_DMA_MMAP_PGPROT if MMU && !COLDFIRE
         select ARCH_HAS_SYNC_DMA_FOR_DEVICE if HAS_DMA
         select ARCH_MIGHT_HAVE_PC_PARPORT if ISA
         select ARCH_NO_COHERENT_DMA_MMAP if !MMU
         select ARCH_NO_PREEMPT if !COLDFIRE
+        select DMA_DIRECT_REMAP if HAS_DMA && MMU && !COLDFIRE
         select HAVE_IDE
         select HAVE_AOUT if MMU
         select HAVE_DEBUG_BUGVERBOSE
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>