1 files changed, 66 insertions, 0 deletions
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index c05c6bf8a2..81def0afd3 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -241,6 +241,72 @@ static inline void sync(void)
 #define __iormb()	dmb()
 #define __iowmb()	dmb()
 
+/*
+ * Read/write from/to an (offsettable) iomem cookie. It might be a PIO
+ * access or a MMIO access, these functions don't care. The info is
+ * encoded in the hardware mapping set up by the mapping functions
+ * (or the cookie itself, depending on implementation and hw).
+ *
+ * The generic routines don't assume any hardware mappings, and just
+ * encode the PIO/MMIO as part of the cookie. They coldly assume that
+ * the MMIO IO mappings are not in the low address range.
+ *
+ * Architectures for which this is not true can't use this generic
+ * implementation and should do their own copy.
+ */
+
+/*
+ * We assume that all the low physical PIO addresses (0-0xffff) always
+ * PIO. That means we can do some sanity checks on the low bits, and
+ * don't need to just take things for granted.
+ */
+#define PIO_RESERVED	0x10000UL
+
+/*
+ * Ugly macros are a way of life.
+ */
+#define IO_COND(addr, is_pio, is_mmio) do {			\
+	unsigned long port = (unsigned long __force)addr;	\
+	if (port >= PIO_RESERVED) {				\
+		is_mmio;					\
+	} else {						\
+		is_pio;						\
+	}							\
+} while (0)
+
+static inline u8 ioread8(const volatile void __iomem *addr)
+{
+	IO_COND(addr, return inb(port), return readb(addr));
+	return 0xff;
+}
+
+static inline u16 ioread16(const volatile void __iomem *addr)
+{
+	IO_COND(addr, return inw(port), return readw(addr));
+	return 0xffff;
+}
+
+static inline u32 ioread32(const volatile void __iomem *addr)
+{
+	IO_COND(addr, return inl(port), return readl(addr));
+	return 0xffffffff;
+}
+
+static inline void iowrite8(u8 value, volatile void __iomem *addr)
+{
+	IO_COND(addr, outb(value, port), writeb(value, addr));
+}
+
+static inline void iowrite16(u16 value, volatile void __iomem *addr)
+{
+	IO_COND(addr, outw(value, port), writew(value, addr));
+}
+
+static inline void iowrite32(u32 value, volatile void __iomem *addr)
+{
+	IO_COND(addr, outl(value, port), writel(value, addr));
+}
+
 #include <asm-generic/io.h>
 
 #endif /* _ASM_IO_H */