[MIPS] Make I/O helpers more customizable

    
1. Move ioswab*() and __mem_ioswab*() to mangle-port.h.  This gets rid
   of CONFIG_SGI_IP22 from include/asm-mips/io.h.
    
2. Pass a virtual address to *ioswab*().  Then we can provide
   mach-specific *ioswab*() and can do every evil thing based on its
   argument.  It could be useful on machines which have regions with
   different endian conversion scheme.
    
3. Call __swizzle_addr*() _after_ adding mips_io_port_base.  This
   unifies the meaning of the argument of __swizzle_addr*() (always
   virtual address).  Then mach-specific __swizzle_addr*() can do every
   evil thing based on the argument.
    
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 36 insertions, 0 deletions

diff --git a/include/asm-mips/mach-generic/mangle-port.h b/include/asm-mips/mach-generic/mangle-port.h
index 4a98d83..6e1b0c0 100644
--- a/include/asm-mips/mach-generic/mangle-port.h
+++ b/include/asm-mips/mach-generic/mangle-port.h
@@ -13,4 +13,40 @@
 #define __swizzle_addr_l(port)	(port)
 #define __swizzle_addr_q(port)	(port)
 
+/*
+ * Sane hardware offers swapping of PCI/ISA I/O space accesses in hardware;
+ * less sane hardware forces software to fiddle with this...
+ *
+ * Regardless, if the host bus endianness mismatches that of PCI/ISA, then
+ * you can't have the numerical value of data and byte addresses within
+ * multibyte quantities both preserved at the same time.  Hence two
+ * variations of functions: non-prefixed ones that preserve the value
+ * and prefixed ones that preserve byte addresses.  The latters are
+ * typically used for moving raw data between a peripheral and memory (cf.
+ * string I/O functions), hence the "__mem_" prefix.
+ */
+#if defined(CONFIG_SWAP_IO_SPACE)
+
+# define ioswabb(a,x)		(x)
+# define __mem_ioswabb(a,x)	(x)
+# define ioswabw(a,x)		le16_to_cpu(x)
+# define __mem_ioswabw(a,x)	(x)
+# define ioswabl(a,x)		le32_to_cpu(x)
+# define __mem_ioswabl(a,x)	(x)
+# define ioswabq(a,x)		le64_to_cpu(x)
+# define __mem_ioswabq(a,x)	(x)
+
+#else
+
+# define ioswabb(a,x)		(x)
+# define __mem_ioswabb(a,x)	(x)
+# define ioswabw(a,x)		(x)
+# define __mem_ioswabw(a,x)	cpu_to_le16(x)
+# define ioswabl(a,x)		(x)
+# define __mem_ioswabl(a,x)	cpu_to_le32(x)
+# define ioswabq(a,x)		(x)
+# define __mem_ioswabq(a,x)	cpu_to_le32(x)
+
+#endif
+
 #endif /* __ASM_MACH_GENERIC_MANGLE_PORT_H */