x86: Add 64-bit memory-mapped I/O functions

Add readq() and writeq() definitions for x86.

Please note: in 32-bit code readq/writeq will generate two 32-bit
memory access instructions instead of one atomic 64-bit operation.
Signed-off-by: NIvan Gorinov <ivan.gorinov@intel.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: NBin Meng <bmeng.cn@gmail.com>

arch/x86/include/asm/io.h

@@ -61,16 +61,20 @@
 #define readb(addr) (*(volatile unsigned char *) (addr))
 #define readw(addr) (*(volatile unsigned short *) (addr))
 #define readl(addr) (*(volatile unsigned int *) (addr))
+#define readq(addr) (*(volatile unsigned long long *) (addr))
 #define __raw_readb readb
 #define __raw_readw readw
 #define __raw_readl readl
+#define __raw_readq readq
 
 #define writeb(b,addr) (*(volatile unsigned char *) (addr) = (b))
 #define writew(b,addr) (*(volatile unsigned short *) (addr) = (b))
 #define writel(b,addr) (*(volatile unsigned int *) (addr) = (b))
+#define writeq(b,addr) (*(volatile unsigned long long *) (addr) = (b))
 #define __raw_writeb writeb
 #define __raw_writew writew
 #define __raw_writel writel
+#define __raw_writeq writeq
 
 #define memset_io(a,b,c)	memset((a),(b),(c))
 #define memcpy_fromio(a,b,c)	memcpy((a),(b),(c))