drivers: base: cacheinfo: Add helper to search cacheinfo by of_node

hulk inclusion
category: feature
feature: ARM MPAM support
bugzilla: 48265
CVE: NA

--------------------------------

The MPAM ACPI table holds a PPTT-offset that describes a cache. Add a
helper cacheinfo_shared_cpu_map_search() to search the cacheinfo
structures for a cache that represents this firmware description.

The cacheinfo structures are freed and allocated over CPU online/offline,
the caller of this helper must hold the cpu-hotplug read lock while
the helper runs, and while it holds the return value.
Signed-off-by: NJames Morse <james.morse@arm.com>
Link: http://www.linux-arm.org/git?p=linux-jm.git;a=patch;h=9e5b7ec7c145019f7160c56795ede536f0de5347Signed-off-by: NWang ShaoBo <bobo.shaobowang@huawei.com>
Signed-off-by: NHongbo Yao <yaohongbo@huawei.com>
Reviewed-by: NCheng Jian <cj.chengjian@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/base/cacheinfo.c

@@ -213,6 +213,34 @@ int __weak cache_setup_acpi(unsigned int cpu)
 	return -ENOTSUPP;
 }
 
+/**
+ * cacheinfo_shared_cpu_map_search() - find an instance of struct cacheinfo
+ * from the provided firmware description.
+ * Caller must hold cpus_read_lock() until its finished with the cacheinfo.
+ *
+ * Return a CPUs cache leaf described @fw_desc, or NULL.
+ */
+struct cacheinfo *cacheinfo_shared_cpu_map_search(void *fw_token)
+{
+	struct cacheinfo *iter;
+	unsigned int cpu, index;
+	struct cpu_cacheinfo *cpu_ci;
+
+	for_each_online_cpu(cpu) {
+		cpu_ci = get_cpu_cacheinfo(cpu);
+
+		for (index = 0; index < cache_leaves(cpu); index++) {
+			iter = cpu_ci->info_list + index;
+
+			if (iter->fw_token == fw_token) {
+				return iter;
+			}
+		}
+	}
+
+	return NULL;
+}
+
 unsigned int coherency_max_size;
 
 static int cache_shared_cpu_map_setup(unsigned int cpu)

include/linux/cacheinfo.h

@@ -98,6 +98,7 @@ int func(unsigned int cpu)					\
 }
 
 struct cpu_cacheinfo *get_cpu_cacheinfo(unsigned int cpu);
+struct cacheinfo *cacheinfo_shared_cpu_map_search(void *fw_desc);
 int init_cache_level(unsigned int cpu);
 int populate_cache_leaves(unsigned int cpu);
 int cache_setup_acpi(unsigned int cpu);