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-rw-r--r--arch/metag/mm/cache.c79
1 files changed, 79 insertions, 0 deletions
diff --git a/arch/metag/mm/cache.c b/arch/metag/mm/cache.c
index 89da74a80ea..4dd96e457fa 100644
--- a/arch/metag/mm/cache.c
+++ b/arch/metag/mm/cache.c
@@ -14,6 +14,7 @@
#include <linux/io.h>
#include <asm/cacheflush.h>
#include <asm/core_reg.h>
+#include <asm/global_lock.h>
#include <asm/metag_isa.h>
#include <asm/metag_mem.h>
#include <asm/metag_regs.h>
@@ -36,6 +37,82 @@ static int icache_set_shift = METAG_TBI_CACHE_SIZE_BASE_LOG2
static unsigned char dcache_sets_log2 = DEFAULT_CACHE_WAYS_LOG2;
static unsigned char icache_sets_log2 = DEFAULT_CACHE_WAYS_LOG2;
+#ifndef CONFIG_METAG_META12
+/**
+ * metag_lnkget_probe() - Probe whether lnkget/lnkset go around the cache
+ */
+static volatile u32 lnkget_testdata[16] __initdata __aligned(64);
+
+#define LNKGET_CONSTANT 0xdeadbeef
+
+void __init metag_lnkget_probe(void)
+{
+ int temp;
+ long flags;
+
+ /*
+ * It's conceivable the user has configured a globally coherent cache
+ * shared with non-Linux hardware threads, so use LOCK2 to prevent them
+ * from executing and causing cache eviction during the test.
+ */
+ __global_lock2(flags);
+
+ /* read a value to bring it into the cache */
+ (void)lnkget_testdata[0];
+ lnkget_testdata[0] = 0;
+
+ /* lnkget/lnkset it to modify it */
+ asm volatile(
+ "1: LNKGETD %0, [%1]\n"
+ " LNKSETD [%1], %2\n"
+ " DEFR %0, TXSTAT\n"
+ " ANDT %0, %0, #HI(0x3f000000)\n"
+ " CMPT %0, #HI(0x02000000)\n"
+ " BNZ 1b\n"
+ : "=&d" (temp)
+ : "da" (&lnkget_testdata[0]), "bd" (LNKGET_CONSTANT)
+ : "cc");
+
+ /* re-read it to see if the cached value changed */
+ temp = lnkget_testdata[0];
+
+ __global_unlock2(flags);
+
+ /* flush the cache line to fix any incoherency */
+ __builtin_dcache_flush((void *)&lnkget_testdata[0]);
+
+#if defined(CONFIG_METAG_LNKGET_AROUND_CACHE)
+ /* if the cache is right, LNKGET_AROUND_CACHE is unnecessary */
+ if (temp == LNKGET_CONSTANT)
+ pr_info("LNKGET/SET go through cache but CONFIG_METAG_LNKGET_AROUND_CACHE=y\n");
+#elif defined(CONFIG_METAG_ATOMICITY_LNKGET)
+ /*
+ * if the cache is wrong, LNKGET_AROUND_CACHE is really necessary
+ * because the kernel is configured to use LNKGET/SET for atomicity
+ */
+ WARN(temp != LNKGET_CONSTANT,
+ "LNKGET/SET go around cache but CONFIG_METAG_LNKGET_AROUND_CACHE=n\n"
+ "Expect kernel failure as it's used for atomicity primitives\n");
+#elif defined(CONFIG_SMP)
+ /*
+ * if the cache is wrong, LNKGET_AROUND_CACHE should be used or the
+ * gateway page won't flush and userland could break.
+ */
+ WARN(temp != LNKGET_CONSTANT,
+ "LNKGET/SET go around cache but CONFIG_METAG_LNKGET_AROUND_CACHE=n\n"
+ "Expect userland failure as it's used for user gateway page\n");
+#else
+ /*
+ * if the cache is wrong, LNKGET_AROUND_CACHE is set wrong, but it
+ * doesn't actually matter as it doesn't have any effect on !SMP &&
+ * !ATOMICITY_LNKGET.
+ */
+ if (temp != LNKGET_CONSTANT)
+ pr_warn("LNKGET/SET go around cache but CONFIG_METAG_LNKGET_AROUND_CACHE=n\n");
+#endif
+}
+#endif /* !CONFIG_METAG_META12 */
+
/**
* metag_cache_probe() - Probe L1 cache configuration.
*
@@ -68,6 +145,8 @@ void __init metag_cache_probe(void)
dcache_set_shift += (config & METAC_CORECFG2_DCSZ_BITS)
>> METAC_CORECFG2_DCSZ_S;
dcache_set_shift -= dcache_sets_log2;
+
+ metag_lnkget_probe();
#else
/* Extract cache sizes from global heap segment */
unsigned long val, u;