[ARM] 4585/1: Correctly identify the CPU architecture version

The cpu_architecture() function in arch/arm/kernel/setup.c only works
with cores produced by ARM Ltd. The more generic approach is to read
the ID_MMFR0 register and check for the VMSA or PMSA version
supported. With this patch, the ARM11MPCore would be reported as ARMv7
since its MMU is compatible with ARMv7.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 17 insertions, 4 deletions

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 4de432ec903a..efac7df72d65 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -304,10 +304,23 @@ int cpu_architecture(void)
                 cpu_arch = (processor_id >> 16) & 7;
                 if (cpu_arch)
                         cpu_arch += CPU_ARCH_ARMv3;
-        } else {
-                /* the revised CPUID */
-                cpu_arch = ((processor_id >> 12) & 0xf) - 0xb + CPU_ARCH_ARMv6;
-        }
+        } else if ((processor_id & 0x000f0000) == 0x000f0000) {
+                unsigned int mmfr0;
+
+                /* Revised CPUID format. Read the Memory Model Feature
+                 * Register 0 and check for VMSAv7 or PMSAv7 */
+                asm("mrc        p15, 0, %0, c0, c1, 4"
+                    : "=r" (mmfr0));
+                if ((mmfr0 & 0x0000000f) == 0x00000003 ||
+                    (mmfr0 & 0x000000f0) == 0x00000030)
+                        cpu_arch = CPU_ARCH_ARMv7;
+                else if ((mmfr0 & 0x0000000f) == 0x00000002 ||
+                         (mmfr0 & 0x000000f0) == 0x00000020)
+                        cpu_arch = CPU_ARCH_ARMv6;
+                else
+                        cpu_arch = CPU_ARCH_UNKNOWN;
+        } else
+                cpu_arch = CPU_ARCH_UNKNOWN;
 
         return cpu_arch;
 }