ARM: 7062/1: cache: detect PIPT I-cache using CTR

The Cache Type Register L1Ip field identifies I-caches with a PIPT
policy using the encoding 11b.

This patch extends the cache policy parsing to identify PIPT I-caches
correctly and prevent them from being treated as VIPT aliasing in cases
where they are sufficiently large.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 13 insertions, 2 deletions

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 93e39a3d2c1e..3fe93f75b55a 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -265,6 +265,10 @@ static int cpu_has_aliasing_icache(unsigned int arch)
         int aliasing_icache;
         unsigned int id_reg, num_sets, line_size;
 
+        /* PIPT caches never alias. */
+        if (icache_is_pipt())
+                return 0;
+
         /* arch specifies the register format */
         switch (arch) {
         case CPU_ARCH_ARMv7:
@@ -299,8 +303,14 @@ static void __init cacheid_init(void)
                         /* ARMv7 register format */
                         arch = CPU_ARCH_ARMv7;
                         cacheid = CACHEID_VIPT_NONALIASING;
-                        if ((cachetype & (3 << 14)) == 1 << 14)
+                        switch (cachetype & (3 << 14)) {
+                        case (1 << 14):
                                 cacheid |= CACHEID_ASID_TAGGED;
+                                break;
+                        case (3 << 14):
+                                cacheid |= CACHEID_PIPT;
+                                break;
+                        }
                 } else {
                         arch = CPU_ARCH_ARMv6;
                         if (cachetype & (1 << 23))
@@ -317,10 +327,11 @@ static void __init cacheid_init(void)
         printk("CPU: %s data cache, %s instruction cache\n",
                 cache_is_vivt() ? "VIVT" :
                 cache_is_vipt_aliasing() ? "VIPT aliasing" :
-                cache_is_vipt_nonaliasing() ? "VIPT nonaliasing" : "unknown",
+                cache_is_vipt_nonaliasing() ? "PIPT / VIPT nonaliasing" : "unknown",
                 cache_is_vivt() ? "VIVT" :
                 icache_is_vivt_asid_tagged() ? "VIVT ASID tagged" :
                 icache_is_vipt_aliasing() ? "VIPT aliasing" :
+                icache_is_pipt() ? "PIPT" :
                 cache_is_vipt_nonaliasing() ? "VIPT nonaliasing" : "unknown");
 }