nios2: convert dma_alloc_coherent to use malloc_cache_aligned

Convert dma_alloc_coherent to use memalign.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Reviewed-by: Marek Vasut <marex@denx.de>

arch/nios2/include/asm/dma-mapping.h

 #ifndef __ASM_NIOS2_DMA_MAPPING_H
 #define __ASM_NIOS2_DMA_MAPPING_H
 
-/* dma_alloc_coherent() return cache-line aligned allocation which is mapped
+#include <memalign.h>
+#include <asm/io.h>
+
+/*
+ * dma_alloc_coherent() return cache-line aligned allocation which is mapped
  * to uncached io region.
- *
- * IO_REGION_BASE should be defined in board config header file
- *   0x80000000 for nommu, 0xe0000000 for mmu
  */
-
 static inline void *dma_alloc_coherent(size_t len, unsigned long *handle)
 {
-	void *addr = malloc(len + CONFIG_SYS_DCACHELINE_SIZE);
+	unsigned long addr = (unsigned long)malloc_cache_aligned(len);
+
 	if (!addr)
-		return 0;
-	flush_dcache((unsigned long)addr, len + CONFIG_SYS_DCACHELINE_SIZE);
-	*handle = ((unsigned long)addr +
-		   (CONFIG_SYS_DCACHELINE_SIZE - 1)) &
-		~(CONFIG_SYS_DCACHELINE_SIZE - 1) & ~(IO_REGION_BASE);
-	return (void *)(*handle | IO_REGION_BASE);
-}
+		return NULL;
+
+	invalidate_dcache_range(addr, addr + len);
+	if (handle)
+		*handle = addr;
 
+	return ioremap(addr, len);
+}
 #endif /* __ASM_NIOS2_DMA_MAPPING_H */