linux-kernel - [PATCH v5 18/19] arch_topology: Add support for parsing sockets in /cpu-map

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Date:   Mon, 27 Jun 2022 17:50:46 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     linux-kernel@...r.kernel.org
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Atish Patra <atishp@...shpatra.org>,
        Atish Patra <atishp@...osinc.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Qing Wang <wangqing@...o.com>,
        Rob Herring <robh+dt@...nel.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Ionela Voinescu <ionela.voinescu@....com>,
        Pierre Gondois <pierre.gondois@....com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-riscv@...ts.infradead.org
Subject: [PATCH v5 18/19] arch_topology: Add support for parsing sockets in /cpu-map

Finally let us add support for socket nodes in /cpu-map in the device
tree. Since this may not be present in all the old platforms and even
most of the existing platforms, we need to assume absence of the socket
node indicates that it is a single socket system and handle appropriately.

Also it is likely that most single socket systems skip to as the node
since it is optional.

Link: https://lore.kernel.org/r/20220621192034.3332546-20-sudeep.holla@arm.com
Tested-by: Ionela Voinescu <ionela.voinescu@....com>
Reviewed-by: Ionela Voinescu <ionela.voinescu@....com>
Signed-off-by: Sudeep Holla <sudeep.holla@....com>
---
 drivers/base/arch_topology.c | 37 +++++++++++++++++++++++++++++++-----
 1 file changed, 32 insertions(+), 5 deletions(-)

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index 80184c91c919..7cbe21b1b295 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -545,8 +545,8 @@ static int __init parse_core(struct device_node *core, int package_id,
 	return 0;
 }
 
-static int __init
-parse_cluster(struct device_node *cluster, int cluster_id, int depth)
+static int __init parse_cluster(struct device_node *cluster, int package_id,
+				int cluster_id, int depth)
 {
 	char name[20];
 	bool leaf = true;
@@ -566,7 +566,7 @@ parse_cluster(struct device_node *cluster, int cluster_id, int depth)
 		c = of_get_child_by_name(cluster, name);
 		if (c) {
 			leaf = false;
-			ret = parse_cluster(c, i, depth + 1);
+			ret = parse_cluster(c, package_id, i, depth + 1);
 			of_node_put(c);
 			if (ret != 0)
 				return ret;
@@ -590,7 +590,8 @@ parse_cluster(struct device_node *cluster, int cluster_id, int depth)
 			}
 
 			if (leaf) {
-				ret = parse_core(c, 0, cluster_id, core_id++);
+				ret = parse_core(c, package_id, cluster_id,
+						 core_id++);
 			} else {
 				pr_err("%pOF: Non-leaf cluster with core %s\n",
 				       cluster, name);
@@ -610,6 +611,32 @@ parse_cluster(struct device_node *cluster, int cluster_id, int depth)
 	return 0;
 }
 
+static int __init parse_socket(struct device_node *socket)
+{
+	char name[20];
+	struct device_node *c;
+	bool has_socket = false;
+	int package_id = 0, ret;
+
+	do {
+		snprintf(name, sizeof(name), "socket%d", package_id);
+		c = of_get_child_by_name(socket, name);
+		if (c) {
+			has_socket = true;
+			ret = parse_cluster(c, package_id, -1, 0);
+			of_node_put(c);
+			if (ret != 0)
+				return ret;
+		}
+		package_id++;
+	} while (c);
+
+	if (!has_socket)
+		ret = parse_cluster(socket, 0, -1, 0);
+
+	return ret;
+}
+
 static int __init parse_dt_topology(void)
 {
 	struct device_node *cn, *map;
@@ -630,7 +657,7 @@ static int __init parse_dt_topology(void)
 	if (!map)
 		goto out;
 
-	ret = parse_cluster(map, -1, 0);
+	ret = parse_socket(map);
 	if (ret != 0)
 		goto out_map;
 
-- 
2.36.1