1 files changed, 79 insertions, 0 deletions

diff --git a/arch/metag/mm/cache.c b/arch/metag/mm/cache.c
index 89da74a80ea7..4dd96e457fa2 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;