[ARM] ARMv6: add CPU_HAS_ASID configuration

Presently, we check for the minimum ARM architecture that we're
building for to determine whether we need ASID support.  This is
wrong - if we're going to support a range of CPUs which include
ARMv6 or higher, we need the ASID.

Convert the checks to use a new configuration symbol, and arrange
for ARMv6 and higher CPU entries to select it.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

4 files changed, 12 insertions, 4 deletions

diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
index 3c078e346753..3278e713c32a 100644
--- a/arch/arm/kernel/asm-offsets.c
+++ b/arch/arm/kernel/asm-offsets.c
@@ -85,7 +85,7 @@ int main(void)
   DEFINE(S_OLD_R0,              offsetof(struct pt_regs, ARM_ORIG_r0));
   DEFINE(S_FRAME_SIZE,          sizeof(struct pt_regs));
   BLANK();
-#if __LINUX_ARM_ARCH__ >= 6
+#ifdef CONFIG_CPU_HAS_ASID
   DEFINE(MM_CONTEXT_ID,         offsetof(struct mm_struct, context.id));
   BLANK();
 #endif
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 15f0284010ca..5f472a8b406a 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -351,6 +351,7 @@ config CPU_V6
         select CPU_CACHE_V6
         select CPU_CACHE_VIPT
         select CPU_CP15_MMU
+        select CPU_HAS_ASID
         select CPU_COPY_V6 if MMU
         select CPU_TLB_V6 if MMU
 
@@ -376,6 +377,7 @@ config CPU_V7
         select CPU_CACHE_V7
         select CPU_CACHE_VIPT
         select CPU_CP15_MMU
+        select CPU_HAS_ASID
         select CPU_COPY_V6 if MMU
         select CPU_TLB_V6 if MMU
 
@@ -498,6 +500,12 @@ config CPU_TLB_V6
 
 endif
 
+config CPU_HAS_ASID
+        bool
+        help
+          This indicates whether the CPU has the ASID register; used to
+          tag TLB and possibly cache entries.
+
 config CPU_CP15
         bool
         help
diff --git a/include/asm-arm/mmu.h b/include/asm-arm/mmu.h
index fe2a23b5627b..53099d4ee421 100644
--- a/include/asm-arm/mmu.h
+++ b/include/asm-arm/mmu.h
@@ -4,13 +4,13 @@
 #ifdef CONFIG_MMU
 
 typedef struct {
-#if __LINUX_ARM_ARCH__ >= 6
+#ifdef CONFIG_CPU_HAS_ASID
         unsigned int id;
 #endif
         unsigned int kvm_seq;
 } mm_context_t;
 
-#if __LINUX_ARM_ARCH__ >= 6
+#ifdef CONFIG_CPU_HAS_ASID
 #define ASID(mm)        ((mm)->context.id & 255)
 #else
 #define ASID(mm)        (0)
diff --git a/include/asm-arm/mmu_context.h b/include/asm-arm/mmu_context.h
index 4981ad419198..6913d02ca5d6 100644
--- a/include/asm-arm/mmu_context.h
+++ b/include/asm-arm/mmu_context.h
@@ -20,7 +20,7 @@
 
 void __check_kvm_seq(struct mm_struct *mm);
 
-#if __LINUX_ARM_ARCH__ >= 6
+#ifdef CONFIG_CPU_HAS_ASID
 
 /*
  * On ARMv6, we have the following structure in the Context ID: