nios2: Use asm-generic/io.h

Convert the nios2 architecture to make use of the new asm-generic/io.h to
provide address mapping functions. As nios2 actually performs
non-identity mapping between physical & virtual addresses we can't
simply make use of the generic functions, with the exception of being
able to drop our no-op unmap_physmem() and definitions of unused map
flags.

Feedback from architecture maintainers is welcome.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Thomas Chou <thomas@wytron.com.tw>

arch/nios2/include/asm/io.h

@@ -19,9 +19,6 @@ static inline void sync(void)
  * properties specified by "flags".
  */
 #define MAP_NOCACHE	1
-#define MAP_WRCOMBINE	0
-#define MAP_WRBACK	0
-#define MAP_WRTHROUGH	0
 
 static inline void *
 map_physmem(phys_addr_t paddr, unsigned long len, unsigned long flags)
@@ -32,20 +29,22 @@ map_physmem(phys_addr_t paddr, unsigned long len, unsigned long flags)
 	else
 		return (void *)(paddr | gd->arch.mem_region_base);
 }
+#define map_physmem map_physmem
 
-/*
- * Take down a mapping set up by map_physmem().
- */
-static inline void unmap_physmem(void *vaddr, unsigned long flags)
+static inline void *phys_to_virt(phys_addr_t paddr)
 {
+	DECLARE_GLOBAL_DATA_PTR;
 
+	return (void *)(paddr | gd->arch.mem_region_base);
 }
+#define phys_to_virt phys_to_virt
 
 static inline phys_addr_t virt_to_phys(void * vaddr)
 {
 	DECLARE_GLOBAL_DATA_PTR;
 	return (phys_addr_t)vaddr & gd->arch.physaddr_mask;
 }
+#define virt_to_phys virt_to_phys
 
 #define __raw_writeb(v,a)       (*(volatile unsigned char  *)(a) = (v))
 #define __raw_writew(v,a)       (*(volatile unsigned short *)(a) = (v))
@@ -171,4 +170,6 @@ static inline void outsl (unsigned long port, const void *src, unsigned long cou
 #define memcpy_fromio(a, b, c)		memcpy((a), (void *)(b), (c))
 #define memcpy_toio(a, b, c)		memcpy((void *)(a), (b), (c))
 
+#include <asm-generic/io.h>
+
 #endif /* __ASM_NIOS2_IO_H_ */