Fix cycle counters for ARM v7 CPUs.

Conflicts:

	arch/arm/mach-omap2/board-omap4panda.c

Signed-off-by: Christopher Kenna <cjk@cs.unc.edu>

1 files changed, 31 insertions, 0 deletions

diff --git a/litmus/litmus.c b/litmus/litmus.c
index 1bbad8db1a55..531a2245133d 100644
--- a/litmus/litmus.c
+++ b/litmus/litmus.c
@@ -656,6 +656,35 @@ static struct sysrq_key_op sysrq_kill_rt_tasks_op = {
 
 extern struct sched_plugin linux_sched_plugin;
 
+#if defined(CONFIG_CPU_V7) && !defined(CONFIG_HW_PERF_EVENTS)
+static void __init litmus_enable_perfcounters_v7(void *_ignore)
+{
+        u32 enable_val;
+
+        /* write 1 to enable user-mode access to the performance counter */
+        asm volatile("mcr p15, 0, %0, c9, c14, 0" : : "r" (1));
+
+        /* disable counter overflow interrupts (just in case) */
+        asm volatile("mcr p15, 0, %0, c9, c14, 2" : : "r" (0x8000000f));
+
+        enable_val = 1;         /* bit 1 enables the counters */
+        enable_val |= 2;        /* resets cycle counter to zero */
+        /* performance monitor control register: enable all counters */
+        asm volatile("mcr p15, 0, %0, c9, c12, 0" : : "r"(enable_val));
+
+        /* enables counters (currently just cycle counter) */
+        asm volatile("mcr p15, 0, %0, c9, c12, 1" : : "r"(0x80000000));
+}
+
+static void __init litmus_enable_perfcounters(void)
+{
+        litmus_enable_perfcounters_v7(NULL);
+        smp_call_function(litmus_enable_perfcounters_v7, NULL, 0);
+}
+#else
+#define litmus_enable_perfcounters() do { } while (0)
+#endif
+
 static int __init _init_litmus(void)
 {
         /*      Common initializers,
@@ -691,6 +720,8 @@ static int __init _init_litmus(void)
         init_topology();
 #endif
 
+        litmus_enable_perfcounters();
+
         return 0;
 }