MIPS: Add DMA declare coherent memory support

The ohci-sm501 driver requires dma_declare_coherent_memory().  It is used
by the driver's local memory allocation with dma_alloc_coherent().

Tested on TANBAC TB0287(VR4131 + SM501).

[Ralf: Fixed reject in dma-default.c and removed the entire #if 0'ed block
 in dma-mapping.h instead of just the #if 0.]

Signed-off-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -1,6 +1,7 @@
 config MIPS
 	bool
 	default y
+	select HAVE_GENERIC_DMA_COHERENT
 	select HAVE_IDE
 	select HAVE_OPROFILE
 	select HAVE_ARCH_KGDB

arch/mips/include/asm/dma-mapping.h

@@ -3,6 +3,7 @@
 
 #include <asm/scatterlist.h>
 #include <asm/cache.h>
+#include <asm-generic/dma-coherent.h>
 
 void *dma_alloc_noncoherent(struct device *dev, size_t size,
 			   dma_addr_t *dma_handle, gfp_t flag);
@@ -73,14 +74,4 @@ extern int dma_is_consistent(struct device *dev, dma_addr_t dma_addr);
 extern void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
 	       enum dma_data_direction direction);
 
-#if 0
-#define ARCH_HAS_DMA_DECLARE_COHERENT_MEMORY
-
-extern int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
-	dma_addr_t device_addr, size_t size, int flags);
-extern void dma_release_declared_memory(struct device *dev);
-extern void * dma_mark_declared_memory_occupied(struct device *dev,
-	dma_addr_t device_addr, size_t size);
-#endif
-
 #endif /* _ASM_DMA_MAPPING_H */

arch/mips/mm/dma-default.c

@@ -90,6 +90,9 @@ void *dma_alloc_coherent(struct device *dev, size_t size,
 {
 	void *ret;
 
+	if (dma_alloc_from_coherent(dev, size, dma_handle, &ret))
+		return ret;
+
 	gfp = massage_gfp_flags(dev, gfp);
 
 	ret = (void *) __get_free_pages(gfp, get_order(size));
@@ -122,6 +125,10 @@ void dma_free_coherent(struct device *dev, size_t size, void *vaddr,
 	dma_addr_t dma_handle)
 {
 	unsigned long addr = (unsigned long) vaddr;
+	int order = get_order(size);
+
+	if (dma_release_from_coherent(dev, order, vaddr))
+		return;
 
 	plat_unmap_dma_mem(dev, dma_handle, size, DMA_BIDIRECTIONAL);