linux-kernel - [PATCH v2 1/5] perf/arm_cspmu: Add arm_cspmu_acpi_dev

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Message-ID: <20250923001840.1586078-2-bwicaksono@nvidia.com>
Date: Tue, 23 Sep 2025 00:18:36 +0000
From: Besar Wicaksono <bwicaksono@...dia.com>
To: <will@...nel.org>, <robin.murphy@....com>, <ilkka@...amperecomputing.com>
CC: <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	<linux-tegra@...r.kernel.org>, <suzuki.poulose@....com>,
	<mark.rutland@....com>, <treding@...dia.com>, <jonathanh@...dia.com>,
	<vsethi@...dia.com>, <rwiley@...dia.com>, <sdonthineni@...dia.com>, "Besar
 Wicaksono" <bwicaksono@...dia.com>
Subject: [PATCH v2 1/5] perf/arm_cspmu: Add arm_cspmu_acpi_dev_get

Add interface to get ACPI device associated with the
PMU. This ACPI device may contain additional properties
not covered by the standard properties.

Signed-off-by: Besar Wicaksono <bwicaksono@...dia.com>
---
 drivers/perf/arm_cspmu/arm_cspmu.c | 22 ++++++++++++++++++++++
 drivers/perf/arm_cspmu/arm_cspmu.h |  9 +++++++++
 2 files changed, 31 insertions(+)

diff --git a/drivers/perf/arm_cspmu/arm_cspmu.c b/drivers/perf/arm_cspmu/arm_cspmu.c
index efa9b229e701..75b2d80f783e 100644
--- a/drivers/perf/arm_cspmu/arm_cspmu.c
+++ b/drivers/perf/arm_cspmu/arm_cspmu.c
@@ -1090,6 +1090,28 @@ static int arm_cspmu_acpi_get_cpus(struct arm_cspmu *cspmu)
 
 	return 0;
 }
+
+struct acpi_device *arm_cspmu_acpi_dev_get(const struct arm_cspmu *cspmu)
+{
+	char hid[16];
+	char uid[16];
+	struct acpi_device *adev;
+	const struct acpi_apmt_node *apmt_node;
+
+	apmt_node = arm_cspmu_apmt_node(cspmu->dev);
+	if (!apmt_node || apmt_node->type != ACPI_APMT_NODE_TYPE_ACPI)
+		return NULL;
+
+	memset(hid, 0, sizeof(hid));
+	memset(uid, 0, sizeof(uid));
+
+	memcpy(hid, &apmt_node->inst_primary, sizeof(apmt_node->inst_primary));
+	sprintf(uid, "%u", apmt_node->inst_secondary);
+
+	adev = acpi_dev_get_first_match_dev(hid, uid, -1);
+	return adev;
+}
+EXPORT_SYMBOL_GPL(arm_cspmu_acpi_dev_get);
 #else
 static int arm_cspmu_acpi_get_cpus(struct arm_cspmu *cspmu)
 {
diff --git a/drivers/perf/arm_cspmu/arm_cspmu.h b/drivers/perf/arm_cspmu/arm_cspmu.h
index 19684b76bd96..9c5f11f98acd 100644
--- a/drivers/perf/arm_cspmu/arm_cspmu.h
+++ b/drivers/perf/arm_cspmu/arm_cspmu.h
@@ -8,6 +8,7 @@
 #ifndef __ARM_CSPMU_H__
 #define __ARM_CSPMU_H__
 
+#include <linux/acpi.h>
 #include <linux/bitfield.h>
 #include <linux/cpumask.h>
 #include <linux/device.h>
@@ -222,4 +223,12 @@ int arm_cspmu_impl_register(const struct arm_cspmu_impl_match *impl_match);
 /* Unregister vendor backend. */
 void arm_cspmu_impl_unregister(const struct arm_cspmu_impl_match *impl_match);
 
+#if defined(CONFIG_ACPI)
+/**
+ * Get ACPI device associated with the PMU.
+ * The caller is responsible for calling acpi_dev_put() on the returned device.
+ */
+struct acpi_device *arm_cspmu_acpi_dev_get(const struct arm_cspmu *cspmu);
+#endif
+
 #endif /* __ARM_CSPMU_H__ */
-- 
2.50.1