linux-kernel - [PATCH 12/12] cacheinfo: Set cache 'id' based on DT data

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Message-Id: <20211006164332.1981454-13-robh@kernel.org>
Date:   Wed,  6 Oct 2021 11:43:32 -0500
From:   Rob Herring <robh@...nel.org>
To:     Russell King <linux@...linux.org.uk>,
        James Morse <james.morse@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Guo Ren <guoren@...nel.org>,
        Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        Stafford Horne <shorne@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>, x86@...nel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        bcm-kernel-feedback-list@...adcom.com,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-csky@...r.kernel.org, openrisc@...ts.librecores.org,
        linuxppc-dev@...ts.ozlabs.org, linux-riscv@...ts.infradead.org,
        linux-sh@...r.kernel.org, devicetree@...r.kernel.org
Subject: [PATCH 12/12] cacheinfo: Set cache 'id' based on DT data

Use the minimum CPU h/w id of the CPUs associated with the cache for the
cache 'id'. This will provide a stable id value for a given system. As
we need to check all possible CPUs, we can't use the shared_cpu_map
which is just online CPUs. As there's not a cache to CPUs mapping in DT,
we have to walk all CPU nodes and then walk cache levels.

Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>
Signed-off-by: Rob Herring <robh@...nel.org>
---
 drivers/base/cacheinfo.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 66d10bdb863b..44547fd96f72 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -136,6 +136,31 @@ static bool cache_node_is_unified(struct cacheinfo *this_leaf,
 	return of_property_read_bool(np, "cache-unified");
 }
 
+static void cache_of_set_id(struct cacheinfo *this_leaf, struct device_node *np)
+{
+	struct device_node *cpu;
+	unsigned long min_id = ~0UL;
+
+	for_each_of_cpu_node(cpu) {
+		struct device_node *cache_node = cpu;
+		u64 id = of_get_cpu_hwid(cache_node, 0);
+
+		while ((cache_node = of_find_next_cache_node(cache_node))) {
+			if ((cache_node == np) && (id < min_id)) {
+				min_id = id;
+				of_node_put(cache_node);
+				break;
+			}
+			of_node_put(cache_node);
+		}
+	}
+
+	if (min_id != ~0UL) {
+		this_leaf->id = min_id;
+		this_leaf->attributes |= CACHE_ID;
+	}
+}
+
 static void cache_of_set_props(struct cacheinfo *this_leaf,
 			       struct device_node *np)
 {
@@ -151,6 +176,7 @@ static void cache_of_set_props(struct cacheinfo *this_leaf,
 	cache_get_line_size(this_leaf, np);
 	cache_nr_sets(this_leaf, np);
 	cache_associativity(this_leaf);
+	cache_of_set_id(this_leaf, np);
 }
 
 static int cache_setup_of_node(unsigned int cpu)
-- 
2.30.2