[PATCH 2/6] cacheinfo: Set cache 'id' based on DT data

[Rob Herring <robh@kernel.org>]

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. There's not a cache to CPUs mapping in DT, so
we have to walk all CPU nodes and then walk cache levels.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
---
v2:
 - Loop with for_each_possible_cpu instead of for_each_of_cpu_node as
   we will need the logical cpu numbers.
---
 drivers/base/cacheinfo.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 66d10bdb863b..21accddf8f5f 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -136,6 +136,36 @@ 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)
+{
+	int cpu;
+	unsigned long min_id = ~0UL;
+
+	for_each_possible_cpu(cpu) {
+		u64 id;
+		struct device_node *cache_node, *cpu_node;
+
+		cache_node = cpu_node = of_get_cpu_node(cpu, NULL);
+		id = of_get_cpu_hwid(cpu_node, 0);
+		while ((cache_node = of_find_next_cache_node(cache_node))) {
+			if (cache_node == np) {
+				if (id < min_id) {
+					min_id = id;
+					of_node_put(cache_node);
+					break;
+				}
+			}
+			of_node_put(cache_node);
+		}
+		of_node_put(cpu_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 +181,7 @@ 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)
-- 
2.32.0