linux-kernel - [PATCH v4 01/12] arm-cci: Define CCI counter period

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Message-Id: <1450374559-23315-2-git-send-email-suzuki.poulose@arm.com>
Date:	Thu, 17 Dec 2015 17:49:08 +0000
From:	"Suzuki K. Poulose" <suzuki.poulose@....com>
To:	linux-arm-kernel@...ts.infradead.org
Cc:	linux-kernel@...r.kernel.org, mark.rutland@....com,
	punit.agrawal@....com, arm@...nel.org,
	"Suzuki K. Poulose" <suzuki.poulose@....com>
Subject: [PATCH v4 01/12] arm-cci: Define CCI counter period

Instead of hard coding the period we program on the PMU
counters, define a symbol.

Cc: Mark Rutland <mark.rutland@....com>
Cc: Punit Agrawal <punit.agrawal@....com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@....com>
---
 drivers/bus/arm-cci.c |   19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
index ee47e6b..3786879 100644
--- a/drivers/bus/arm-cci.c
+++ b/drivers/bus/arm-cci.c
@@ -85,6 +85,14 @@ static const struct of_device_id arm_cci_matches[] = {
 #define CCI_PMU_CNTR_MASK		((1ULL << 32) -1)
 #define CCI_PMU_CNTR_LAST(cci_pmu)	(cci_pmu->num_cntrs - 1)
 
+/*
+ * The CCI PMU counters have a period of 2^32. To account for the
+ * possiblity of extreme interrupt latency we program for a period of
+ * half that. Hopefully we can handle the interrupt before another 2^31
+ * events occur and the counter overtakes its previous value.
+ */
+#define CCI_CNTR_PERIOD		(1UL << 31)
+
 #define CCI_PMU_MAX_HW_CNTRS(model) \
 	((model)->num_hw_cntrs + (model)->fixed_hw_cntrs)
 
@@ -797,15 +805,8 @@ static void pmu_read(struct perf_event *event)
 void pmu_event_set_period(struct perf_event *event)
 {
 	struct hw_perf_event *hwc = &event->hw;
-	/*
-	 * The CCI PMU counters have a period of 2^32. To account for the
-	 * possiblity of extreme interrupt latency we program for a period of
-	 * half that. Hopefully we can handle the interrupt before another 2^31
-	 * events occur and the counter overtakes its previous value.
-	 */
-	u64 val = 1ULL << 31;
-	local64_set(&hwc->prev_count, val);
-	pmu_write_counter(event, val);
+	local64_set(&hwc->prev_count, CCI_CNTR_PERIOD);
+	pmu_write_counter(event, CCI_CNTR_PERIOD);
 }
 
 static irqreturn_t pmu_handle_irq(int irq_num, void *dev)
-- 
1.7.9.5

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