[ARM] Introduce new bitmask based cache type macros

Rather than trying to (inaccurately) decode the cache type from the
registers each time we need to decide what type of cache we have,
use a bitmask initialized early during boot.

Since the setup is a one-off initialization, we can be a little more
clever and take account of the CPU architecture as well.

Note that we continue to achieve the compactness on optimised kernels
by forcing tests to always-false or always-true as appropriate, thereby
allowing the compiler to do build-time code elimination.

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

1 files changed, 22 insertions, 0 deletions

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 1939c904dae3..5b121d81f9eb 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -67,6 +67,8 @@ unsigned int processor_id;
 EXPORT_SYMBOL(processor_id);
 unsigned int __machine_arch_type;
 EXPORT_SYMBOL(__machine_arch_type);
+unsigned int cacheid;
+EXPORT_SYMBOL(cacheid);
 
 unsigned int __atags_pointer __initdata;
 
@@ -229,6 +231,25 @@ int cpu_architecture(void)
 	return cpu_arch;
 }
 
+static void __init cacheid_init(void)
+{
+	unsigned int cachetype = read_cpuid_cachetype();
+	unsigned int arch = cpu_architecture();
+
+	if (arch >= CPU_ARCH_ARMv7) {
+		cacheid = CACHEID_VIPT_NONALIASING;
+		if ((cachetype & (3 << 14)) == 1 << 14)
+			cacheid |= CACHEID_ASID_TAGGED;
+	} else if (arch >= CPU_ARCH_ARMv6) {
+		if (cachetype & (1 << 23))
+			cacheid = CACHEID_VIPT_ALIASING;
+		else
+			cacheid = CACHEID_VIPT_NONALIASING;
+	} else {
+		cacheid = CACHEID_VIVT;
+	}
+}
+
 /*
  * These functions re-use the assembly code in head.S, which
  * already provide the required functionality.
@@ -278,6 +299,7 @@ static void __init setup_processor(void)
 	elf_hwcap &= ~HWCAP_THUMB;
 #endif
 
+	cacheid_init();
 	cpu_proc_init();
 }