[ltt-dev] [PATCH 3/3] lttng: MIPS: Use 64 bit counter for trace clock on Octeon CPUs.

[David Daney]

Cavium Octeon CPUs have a 64-bit cycle counter that is synchronized
when the CPUs are brought on-line.  So for this case we don't need any
fancy stuff.

Signed-off-by: David Daney <ddaney at caviumnetworks.com>
---
 arch/mips/Kconfig                   |    4 +-
 arch/mips/include/asm/trace-clock.h |   39 ++++++++++++++++++++++++++++++++++-
 arch/mips/kernel/smp.c              |    2 +
 3 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index a690e9b..9e91e8c 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1782,8 +1782,8 @@ config HAVE_GET_CYCLES_32
 	def_bool y
 	depends on !CPU_R4400_WORKAROUNDS
 	select HAVE_TRACE_CLOCK
-	select HAVE_TRACE_CLOCK_32_TO_64
-	select HAVE_UNSYNCHRONIZED_TSC
+	select HAVE_TRACE_CLOCK_32_TO_64 if (!CPU_CAVIUM_OCTEON)
+	select HAVE_UNSYNCHRONIZED_TSC if (!CPU_CAVIUM_OCTEON)
 
 #
 # Use the generic interrupt handling code in kernel/irq/:
diff --git a/arch/mips/include/asm/trace-clock.h b/arch/mips/include/asm/trace-clock.h
index 3d8cb0f..a052f42 100644
--- a/arch/mips/include/asm/trace-clock.h
+++ b/arch/mips/include/asm/trace-clock.h
@@ -12,6 +12,43 @@
 
 #define TRACE_CLOCK_MIN_PROBE_DURATION 200
 
+#ifdef CONFIG_CPU_CAVIUM_OCTEON
+
+#include <asm/octeon/octeon.h>
+
+#define TC_HW_BITS			64
+
+static inline u32 trace_clock_read32(void)
+{
+	return (u32)read_c0_cvmcount(); /* only need the 32 LSB */
+}
+
+static inline u64 trace_clock_read64(void)
+{
+	return read_c0_cvmcount();
+}
+
+static inline u64 trace_clock_frequency(void)
+{
+	return octeon_get_clock_rate();
+}
+
+static inline u32 trace_clock_freq_scale(void)
+{
+	return 1;
+}
+
+static inline void get_trace_clock(void)
+{
+	return;
+}
+
+static inline void put_trace_clock(void)
+{
+	return;
+}
+
+#else /* !CONFIG_CPU_CAVIUM_OCTEON */
 /*
  * Number of hardware clock bits. The higher order bits are expected to be 0.
  * If the hardware clock source has more than 32 bits, the bits higher than the
@@ -65,7 +102,7 @@ static inline void put_trace_clock(void)
 {
 	put_synthetic_tsc();
 }
-
+#endif /* CONFIG_CPU_CAVIUM_OCTEON */
 static inline void set_trace_clock_is_sync(int state)
 {
 }
diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index f8c50d1..42083eb 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -159,7 +159,9 @@ void __init smp_cpus_done(unsigned int max_cpus)
 {
 	mp_ops->cpus_done();
 	synchronise_count_master();
+#ifdef CONFIG_HAVE_UNSYNCHRONIZED_TSC
 	test_tsc_synchronization();
+#endif
 }
 
 /* called from main before smp_init() */
-- 
1.6.6.1