Blackfin: unify memory region checks between kgdb and traps

The kgdb (in multiple places) and traps code developed pretty much
identical checks for how to access different regions of the Blackfin
memory map, but each wasn't 100%, so unify them to avoid duplication,
bitrot, and bugs with edge cases.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/include/asm/uaccess.h

@@ -265,4 +265,26 @@ __clear_user(void *to, unsigned long n)
 
 #define clear_user(to, n) __clear_user(to, n)
 
+/* How to interpret these return values:
+ *	CORE:      can be accessed by core load or dma memcpy
+ *	CORE_ONLY: can only be accessed by core load
+ *	DMA:       can only be accessed by dma memcpy
+ *	IDMA:      can only be accessed by interprocessor dma memcpy (BF561)
+ *	ITEST:     can be accessed by isram memcpy or dma memcpy
+ */
+enum {
+	BFIN_MEM_ACCESS_CORE = 0,
+	BFIN_MEM_ACCESS_CORE_ONLY,
+	BFIN_MEM_ACCESS_DMA,
+	BFIN_MEM_ACCESS_IDMA,
+	BFIN_MEM_ACCESS_ITEST,
+};
+/**
+ *	bfin_mem_access_type() - what kind of memory access is required
+ *	@addr:   the address to check
+ *	@size:   number of bytes needed
+ *	@return: <0 is error, >=0 is BFIN_MEM_ACCESS_xxx enum (see above)
+ */
+int bfin_mem_access_type(unsigned long addr, unsigned long size);
+
 #endif				/* _BLACKFIN_UACCESS_H */