sh: Support I/O space swapping where needed.

This adopts a trimmed down version of the MIPS port mangling interface
limited to the I/O swabbing for platforms that can't use little endian
accessors. For platforms with mixed I/O spaces involving PCI it will
still be necessary to enable byte swapping at the host controller level.
Attention needs to be paid to all of host controller endianness, CPU
endianness, and whether I/O accesses are explicitly swapped or not via
SWAP_IO_SPACE. Fortunately the platforms that need this are in the
minority.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 49 insertions, 0 deletions

diff --git a/arch/sh/include/mach-common/mach/mangle-port.h b/arch/sh/include/mach-common/mach/mangle-port.h
new file mode 100644
index 000000000000..4ca1769a0f12
--- /dev/null
+++ b/arch/sh/include/mach-common/mach/mangle-port.h
@@ -0,0 +1,49 @@
+/*
+ * SH version cribbed from the MIPS copy:
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2003, 2004 Ralf Baechle
+ */
+#ifndef __MACH_COMMON_MANGLE_PORT_H
+#define __MACH_COMMON_MANGLE_PORT_H
+
+/*
+ * 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(x)		(x)
+# define __mem_ioswabb(x)	(x)
+# define ioswabw(x)		le16_to_cpu(x)
+# define __mem_ioswabw(x)	(x)
+# define ioswabl(x)		le32_to_cpu(x)
+# define __mem_ioswabl(x)	(x)
+# define ioswabq(x)		le64_to_cpu(x)
+# define __mem_ioswabq(x)	(x)
+
+#else
+
+# define ioswabb(x)		(x)
+# define __mem_ioswabb(x)	(x)
+# define ioswabw(x)		(x)
+# define __mem_ioswabw(x)	cpu_to_le16(x)
+# define ioswabl(x)		(x)
+# define __mem_ioswabl(x)	cpu_to_le32(x)
+# define ioswabq(x)		(x)
+# define __mem_ioswabq(x)	cpu_to_le32(x)
+
+#endif
+
+#endif /* __MACH_COMMON_MANGLE_PORT_H */