linux-kernel - [PATCH v3 1/4] perf: arm_cspmu: Split 64-bit write to 32-bit writes

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Message-Id: <20230607083139.3498788-2-ilkka@os.amperecomputing.com>
Date:   Wed,  7 Jun 2023 01:31:36 -0700
From:   Ilkka Koskinen <ilkka@...amperecomputing.com>
To:     Jonathan Corbet <corbet@....net>, Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Besar Wicaksono <bwicaksono@...dia.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Robin Murphy <robin.murphy@....com>
Cc:     linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Ilkka Koskinen <ilkka@...amperecomputing.com>
Subject: [PATCH v3 1/4] perf: arm_cspmu: Split 64-bit write to 32-bit writes

Split the 64-bit register accesses if 64-bit access is not supported
by the PMU.

Signed-off-by: Ilkka Koskinen <ilkka@...amperecomputing.com>
---
 drivers/perf/arm_cspmu/arm_cspmu.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/perf/arm_cspmu/arm_cspmu.c b/drivers/perf/arm_cspmu/arm_cspmu.c
index a3f1c410b417..f8b4a149eb88 100644
--- a/drivers/perf/arm_cspmu/arm_cspmu.c
+++ b/drivers/perf/arm_cspmu/arm_cspmu.c
@@ -702,7 +702,10 @@ static void arm_cspmu_write_counter(struct perf_event *event, u64 val)
 	if (use_64b_counter_reg(cspmu)) {
 		offset = counter_offset(sizeof(u64), event->hw.idx);
 
-		writeq(val, cspmu->base1 + offset);
+		if (supports_64bit_atomics(cspmu))
+			writeq(val, cspmu->base1 + offset);
+		else
+			lo_hi_writeq(val, cspmu->base1 + offset);
 	} else {
 		offset = counter_offset(sizeof(u32), event->hw.idx);
 
-- 
2.40.1