arm64: add MIDR_EL1 field accessors

The MIDR_EL1 register is composed of a number of bitfields, and uses of
the fields has so far involved open-coding of the shifts and masks
required.

This patch adds shifts and masks for each of the MIDR_EL1 subfields, and
also provides accessors built atop of these. Existing uses within
cputype.h are updated to use these accessors.

The read_cpuid_part_number macro is modified to return the extracted
bitfield rather than returning the value in-place with all other fields
(including revision) masked out, to better match the other accessors.
As the value is only used in comparison with the *_CPU_PART_* macros
which are similarly updated, and these values are never exposed to
userspace, this change should not affect any functionality.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 26 insertions, 7 deletions

diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h
index ed48a3a7836a..379d0b874328 100644
--- a/arch/arm64/include/asm/cputype.h
+++ b/arch/arm64/include/asm/cputype.h
@@ -38,15 +38,34 @@
         __val;                                                          \
 })
 
+#define MIDR_REVISION_MASK      0xf
+#define MIDR_REVISION(midr)     ((midr) & MIDR_REVISION_MASK)
+#define MIDR_PARTNUM_SHIFT      4
+#define MIDR_PARTNUM_MASK       (0xfff << MIDR_PARTNUM_SHIFT)
+#define MIDR_PARTNUM(midr)      \
+        (((midr) & MIDR_PARTNUM_MASK) >> MIDR_PARTNUM_SHIFT)
+#define MIDR_ARCHITECTURE_SHIFT 16
+#define MIDR_ARCHITECTURE_MASK  (0xf << MIDR_ARCHITECTURE_SHIFT)
+#define MIDR_ARCHITECTURE(midr) \
+        (((midr) & MIDR_ARCHITECTURE_MASK) >> MIDR_ARCHITECTURE_SHIFT)
+#define MIDR_VARIANT_SHIFT      20
+#define MIDR_VARIANT_MASK       (0xf << MIDR_VARIANT_SHIFT)
+#define MIDR_VARIANT(midr)      \
+        (((midr) & MIDR_VARIANT_MASK) >> MIDR_VARIANT_SHIFT)
+#define MIDR_IMPLEMENTOR_SHIFT  24
+#define MIDR_IMPLEMENTOR_MASK   (0xff << MIDR_IMPLEMENTOR_SHIFT)
+#define MIDR_IMPLEMENTOR(midr)  \
+        (((midr) & MIDR_IMPLEMENTOR_MASK) >> MIDR_IMPLEMENTOR_SHIFT)
+
 #define ARM_CPU_IMP_ARM         0x41
 #define ARM_CPU_IMP_APM         0x50
 
-#define ARM_CPU_PART_AEM_V8     0xD0F0
-#define ARM_CPU_PART_FOUNDATION 0xD000
-#define ARM_CPU_PART_CORTEX_A53 0xD030
-#define ARM_CPU_PART_CORTEX_A57 0xD070
+#define ARM_CPU_PART_AEM_V8     0xD0F
+#define ARM_CPU_PART_FOUNDATION 0xD00
+#define ARM_CPU_PART_CORTEX_A57 0xD07
+#define ARM_CPU_PART_CORTEX_A53 0xD03
 
-#define APM_CPU_PART_POTENZA    0x0000
+#define APM_CPU_PART_POTENZA    0x000
 
 #ifndef __ASSEMBLY__
 
@@ -67,12 +86,12 @@ static inline u64 __attribute_const__ read_cpuid_mpidr(void)
 
 static inline unsigned int __attribute_const__ read_cpuid_implementor(void)
 {
-        return (read_cpuid_id() & 0xFF000000) >> 24;
+        return MIDR_IMPLEMENTOR(read_cpuid_id());
 }
 
 static inline unsigned int __attribute_const__ read_cpuid_part_number(void)
 {
-        return (read_cpuid_id() & 0xFFF0);
+        return MIDR_PARTNUM(read_cpuid_id());
 }
 
 static inline u32 __attribute_const__ read_cpuid_cachetype(void)