sh: uncached mapping helpers.

This adds some helper routines for uncached mapping support. This
simplifies some of the cases where we need to check the uncached mapping
boundaries in addition to giving us a centralized location for building
more complex manipulation on top of.

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

1 files changed, 28 insertions, 0 deletions

diff --git a/arch/sh/mm/uncached.c b/arch/sh/mm/uncached.c
new file mode 100644
index 0000000..8079069
--- /dev/null
+++ b/arch/sh/mm/uncached.c
@@ -0,0 +1,28 @@
+#include <linux/init.h>
+#include <asm/sizes.h>
+#include <asm/page.h>
+
+/*
+ * This is the offset of the uncached section from its cached alias.
+ *
+ * Legacy platforms handle trivial transitions between cached and
+ * uncached segments by making use of the 1:1 mapping relationship in
+ * 512MB lowmem, others via a special uncached mapping.
+ *
+ * Default value only valid in 29 bit mode, in 32bit mode this will be
+ * updated by the early PMB initialization code.
+ */
+unsigned long cached_to_uncached = SZ_512M;
+unsigned long uncached_size = SZ_512M;
+unsigned long uncached_start, uncached_end;
+
+int virt_addr_uncached(unsigned long kaddr)
+{
+	return (kaddr >= uncached_start) && (kaddr < uncached_end);
+}
+
+void __init uncached_init(void)
+{
+	uncached_start = memory_end;
+	uncached_end = uncached_start + uncached_size;
+}