ARM: prepare for removal of a bunch of <mach/memory.h> files

When the CONFIG_NO_MACH_MEMORY_H symbol is selected by a particular
machine class, the machine specific memory.h include file is no longer
used and can be removed.  In that case the equivalent information can
be obtained dynamically at runtime by enabling CONFIG_ARM_PATCH_PHYS_VIRT
or by specifying the physical memory address at kernel configuration time.

If/when all instances of mach/memory.h are removed then this symbol could
be removed.

Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>

3 files changed, 20 insertions, 2 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 272eadc7a12c..1ecb09bca27e 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -211,6 +211,17 @@ config ARM_PATCH_PHYS_VIRT
           this feature (eg, building a kernel for a single machine) and
           you need to shrink the kernel to the minimal size.
 
+config NO_MACH_MEMORY_H
+        bool
+        help
+          Select this when mach/memory.h is removed.
+
+config PHYS_OFFSET
+        hex "Physical address of main memory"
+        depends on !ARM_PATCH_PHYS_VIRT && NO_MACH_MEMORY_H
+        help
+          Please provide the physical address corresponding to the
+          location of main memory in your system.
 
 source "init/Kconfig"
 
diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
index 90bca427e367..046c915694cd 100644
--- a/arch/arm/include/asm/memory.h
+++ b/arch/arm/include/asm/memory.h
@@ -16,9 +16,12 @@
 #include <linux/compiler.h>
 #include <linux/const.h>
 #include <linux/types.h>
-#include <mach/memory.h>
 #include <asm/sizes.h>
 
+#ifndef CONFIG_NO_MACH_MEMORY_H
+#include <mach/memory.h>
+#endif
+
 /*
  * Allow for constants defined here to be used from assembly code
  * by prepending the UL suffix only with actual C code compilation.
@@ -184,7 +187,11 @@ static inline unsigned long __phys_to_virt(unsigned long x)
 #endif
 
 #ifndef PHYS_OFFSET
+#ifdef PLAT_PHYS_OFFSET
 #define PHYS_OFFSET     PLAT_PHYS_OFFSET
+#else
+#define PHYS_OFFSET     UL(CONFIG_PHYS_OFFSET)
+#endif
 #endif
 
 /*
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 7408fd506656..673c806cc106 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -95,7 +95,7 @@ ENTRY(stext)
         sub     r4, r3, r4                      @ (PHYS_OFFSET - PAGE_OFFSET)
         add     r8, r8, r4                      @ PHYS_OFFSET
 #else
-        ldr     r8, =PLAT_PHYS_OFFSET
+        ldr     r8, =PHYS_OFFSET                @ always constant in this case
 #endif
 
         /*