Introduce map_physmem() and unmap_physmem()

map_physmem() returns a virtual address which can be used to access a
given physical address without involving the cache. unmap_physmem()
should be called when the virtual address returned by map_physmem() is
no longer needed.

This patch adds a stub implementation which simply returns the
physical address cast to a uchar * for all architectures except AVR32,
which converts the physical address to an uncached virtual mapping.
unmap_physmem() is a no-op on all architectures, but if any
architecture needs to do such mappings through the TLB, this is the
hook where those TLB entries can be invalidated.

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/include/asm-ppc/io.h b/include/asm-ppc/io.h
index 86fe8dc..91c9c1e 100644
--- a/include/asm-ppc/io.h
+++ b/include/asm-ppc/io.h
@@ -238,4 +238,30 @@ extern inline void out_be32(volatile unsigned __iomem *addr, int val)
 	__asm__ __volatile__("sync; stw%U0%X0 %1,%0" : "=m" (*addr) : "r" (val));
 }
 
+/*
+ * Given a physical address and a length, return a virtual address
+ * that can be used to access the memory range with the caching
+ * properties specified by "flags".
+ */
+typedef unsigned long phys_addr_t;
+
+#define MAP_NOCACHE	(0)
+#define MAP_WRCOMBINE	(0)
+#define MAP_WRBACK	(0)
+#define MAP_WRTHROUGH	(0)
+
+static inline void *
+map_physmem(phys_addr_t paddr, unsigned long len, unsigned long flags)
+{
+	return (void *)paddr;
+}
+
+/*
+ * Take down a mapping set up by map_physmem().
+ */
+static inline void unmap_physmem(void *vaddr, unsigned long flags)
+{
+
+}
+
 #endif