[PATCH v2 3/5] arm_pmu: Add support for 64bit event counters

Each PMU has a set of 32bit event counters. But in some
special cases, the events could be counted using counters
which are effectively 64bit wide.

e.g, Arm V8 PMUv3 has a 64 bit cycle counter which can count
only the CPU cycles. Also, the PMU can chain the event counters
to effectively count as a 64bit counter.

Add support for tracking the events that uses 64bit counters.
This only affects the periods set for each counter in the core
driver.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <redacted>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
Changes since v1:
 - Rename ARMPMU_EVT_LONG => ARMPMU_EVT_64BIT
---
 drivers/perf/arm_pmu.c       | 14 ++++++++------
 include/linux/perf/arm_pmu.h |  6 ++++++
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 8962d26..ff858e6 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c

@@ -28,9 +28,10 @@
 static DEFINE_PER_CPU(struct arm_pmu *, cpu_armpmu);
 static DEFINE_PER_CPU(int, cpu_irq);
 
-static inline u64 arm_pmu_max_period(void)
+static inline u64 arm_pmu_event_max_period(struct perf_event *event)
 {
-	return (1ULL << 32) - 1;
+	return (event->hw.flags & ARMPMU_EVT_64BIT) ?
+		~0ULL : (1ULL << 32) - 1;
 }