linux-kernel - [PATCH 5/5] cacheinfo: Add helper to find the cache size from cpu+level

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Message-Id: <20250613130356.8080-6-james.morse@arm.com>
Date: Fri, 13 Jun 2025 13:03:56 +0000
From: James Morse <james.morse@....com>
To: linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	sudeep.holla@....com,
	Rob Herring <robh@...nel.org>,
	Ben Horgan <ben.horgan@....com>,
	James Morse <james.morse@....com>
Subject: [PATCH 5/5] cacheinfo: Add helper to find the cache size from cpu+level

The MPAM driver needs to know the size of a cache associated with a
particular CPU. The DT/ACPI agnostic way of doing this is to ask cacheinfo.

Add a helper to do this.

Signed-off-by: James Morse <james.morse@....com>
---
 include/linux/cacheinfo.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index 9c959caf8af8..3f1b6b2e25b5 100644
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h
@@ -148,6 +148,26 @@ static inline int get_cpu_cacheinfo_id(int cpu, int level)
 	return ci ? ci->id : -1;
 }
 
+/*
+ * Get the size of the cache associated with @cpu at level @level.
+ * cpuhp lock must be held.
+ */
+static inline unsigned int get_cpu_cacheinfo_size(int cpu, int level)
+{
+	struct cpu_cacheinfo *ci = get_cpu_cacheinfo(cpu);
+	int i;
+
+	if (!ci->info_list)
+		return 0;
+
+	for (i = 0; i < ci->num_leaves; i++) {
+		if (ci->info_list[i].level == level)
+			return ci->info_list[i].size;
+	}
+
+	return 0;
+}
+
 #if defined(CONFIG_ARM64) || defined(CONFIG_ARM)
 #define use_arch_cache_info()	(true)
 #else
-- 
2.39.5