ARM: provide runtime hook for ioremap/iounmap

We have compile time over-ride of ioremap and iounmap, but an run-time
override is needed for multi-platform builds. This adds an extra function
pointer check, but ioremap is not peformance critical. The option for
compile time selection remains.

The caller variant is used here to provide correct caller information as
ARM can only support level 0 for __builtin_return_address.
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Cc: Russell King <linux@arm.linux.org.uk>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nicolas Pitre <nico@linaro.org>

arch/arm/include/asm/io.h

@@ -83,6 +83,11 @@ extern void __iomem *__arm_ioremap_pfn(unsigned long, unsigned long, size_t, uns
 extern void __iomem *__arm_ioremap(unsigned long, size_t, unsigned int);
 extern void __iomem *__arm_ioremap_exec(unsigned long, size_t, bool cached);
 extern void __iounmap(volatile void __iomem *addr);
+extern void __arm_iounmap(volatile void __iomem *addr);
+
+extern void __iomem * (*arch_ioremap_caller)(unsigned long, size_t,
+	unsigned int, void *);
+extern void (*arch_iounmap)(volatile void __iomem *);
 
 /*
  * Bad read/write accesses...
@@ -266,7 +271,7 @@ extern void _memset_io(volatile void __iomem *, int, size_t);
  */
 #ifndef __arch_ioremap
 #define __arch_ioremap			__arm_ioremap
-#define __arch_iounmap			__iounmap
+#define __arch_iounmap			__arm_iounmap
 #endif
 
 #define ioremap(cookie,size)		__arch_ioremap((cookie), (size), MT_DEVICE)

arch/arm/mm/ioremap.c

@@ -306,11 +306,15 @@ __arm_ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
 }
 EXPORT_SYMBOL(__arm_ioremap_pfn);
 
+void __iomem * (*arch_ioremap_caller)(unsigned long, size_t,
+				      unsigned int, void *) =
+	__arm_ioremap_caller;
+
 void __iomem *
 __arm_ioremap(unsigned long phys_addr, size_t size, unsigned int mtype)
 {
-	return __arm_ioremap_caller(phys_addr, size, mtype,
-			__builtin_return_address(0));
+	return arch_ioremap_caller(phys_addr, size, mtype,
+		__builtin_return_address(0));
 }
 EXPORT_SYMBOL(__arm_ioremap);
 
@@ -369,4 +373,11 @@ void __iounmap(volatile void __iomem *io_addr)
 
 	vunmap(addr);
 }
-EXPORT_SYMBOL(__iounmap);
+
+void (*arch_iounmap)(volatile void __iomem *) = __iounmap;
+
+void __arm_iounmap(volatile void __iomem *io_addr)
+{
+	arch_iounmap(io_addr);
+}
+EXPORT_SYMBOL(__arm_iounmap);