[v7,REPOST,4/9] arm64: parse cpu capacity-dmips-mhz from DT

diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
index 694f6deedbab..b75b0ba2e113 100644
--- a/arch/arm64/kernel/topology.c
+++ b/arch/arm64/kernel/topology.c
@@ -19,10 +19,162 @@ 
 #include <linux/nodemask.h>
 #include <linux/of.h>
 #include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/cpufreq.h>
 
 #include <asm/cputype.h>
 #include <asm/topology.h>
 
+static DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;
+
+unsigned long arch_scale_cpu_capacity(struct sched_domain *sd, int cpu)
+{
+	return per_cpu(cpu_scale, cpu);
+}
+
+static void set_capacity_scale(unsigned int cpu, unsigned long capacity)
+{
+	per_cpu(cpu_scale, cpu) = capacity;
+}
+
+static u32 capacity_scale;
+static u32 *raw_capacity;
+static bool cap_parsing_failed;
+
+static void __init parse_cpu_capacity(struct device_node *cpu_node, int cpu)
+{
+	int ret;
+	u32 cpu_capacity;
+
+	if (cap_parsing_failed)
+		return;
+
+	ret = of_property_read_u32(cpu_node,
+				   "capacity-dmips-mhz",
+				   &cpu_capacity);
+	if (!ret) {
+		if (!raw_capacity) {
+			raw_capacity = kcalloc(num_possible_cpus(),
+					       sizeof(*raw_capacity),
+					       GFP_KERNEL);
+			if (!raw_capacity) {
+				pr_err("cpu_capacity: failed to allocate memory for raw capacities\n");
+				cap_parsing_failed = true;
+				return;
+			}
+		}
+		capacity_scale = max(cpu_capacity, capacity_scale);
+		raw_capacity[cpu] = cpu_capacity;
+		pr_debug("cpu_capacity: %s cpu_capacity=%u (raw)\n",
+			cpu_node->full_name, raw_capacity[cpu]);
+	} else {
+		if (raw_capacity) {
+			pr_err("cpu_capacity: missing %s raw capacity\n",
+				cpu_node->full_name);
+			pr_err("cpu_capacity: partial information: fallback to 1024 for all CPUs\n");
+		}
+		cap_parsing_failed = true;
+		kfree(raw_capacity);
+	}
+}
+
+static void normalize_cpu_capacity(void)
+{
+	u64 capacity;
+	int cpu;
+
+	if (!raw_capacity || cap_parsing_failed)
+		return;
+
+	pr_debug("cpu_capacity: capacity_scale=%u\n", capacity_scale);
+	for_each_possible_cpu(cpu) {
+		pr_debug("cpu_capacity: cpu=%d raw_capacity=%u\n",
+			 cpu, raw_capacity[cpu]);
+		capacity = (raw_capacity[cpu] << SCHED_CAPACITY_SHIFT)
+			/ capacity_scale;
+		set_capacity_scale(cpu, capacity);
+		pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n",
+			cpu, arch_scale_cpu_capacity(NULL, cpu));
+	}
+}
+
+#ifdef CONFIG_CPU_FREQ
+static cpumask_var_t cpus_to_visit;
+static bool cap_parsing_done;
+static void parsing_done_workfn(struct work_struct *work);
+static DECLARE_WORK(parsing_done_work, parsing_done_workfn);
+
+static int
+init_cpu_capacity_callback(struct notifier_block *nb,
+			   unsigned long val,
+			   void *data)
+{
+	struct cpufreq_policy *policy = data;
+	int cpu;
+
+	if (cap_parsing_failed || cap_parsing_done)
+		return 0;
+
+	switch (val) {
+	case CPUFREQ_NOTIFY:
+		pr_debug("cpu_capacity: init cpu capacity for CPUs [%*pbl] (to_visit=%*pbl)\n",
+				cpumask_pr_args(policy->related_cpus),
+				cpumask_pr_args(cpus_to_visit));
+		cpumask_andnot(cpus_to_visit,
+			       cpus_to_visit,
+			       policy->related_cpus);
+		for_each_cpu(cpu, policy->related_cpus) {
+			raw_capacity[cpu] = arch_scale_cpu_capacity(NULL, cpu) *
+					    policy->cpuinfo.max_freq / 1000UL;
+			capacity_scale = max(raw_capacity[cpu], capacity_scale);
+		}
+		if (cpumask_empty(cpus_to_visit)) {
+			normalize_cpu_capacity();
+			kfree(raw_capacity);
+			pr_debug("cpu_capacity: parsing done\n");
+			cap_parsing_done = true;
+			schedule_work(&parsing_done_work);
+		}
+	}
+	return 0;
+}
+
+static struct notifier_block init_cpu_capacity_notifier = {
+	.notifier_call = init_cpu_capacity_callback,
+};
+
+static int __init register_cpufreq_notifier(void)
+{
+	if (cap_parsing_failed)
+		return -EINVAL;
+
+	if (!alloc_cpumask_var(&cpus_to_visit, GFP_KERNEL)) {
+		pr_err("cpu_capacity: failed to allocate memory for cpus_to_visit\n");
+		return -ENOMEM;
+	}
+	cpumask_copy(cpus_to_visit, cpu_possible_mask);
+
+	return cpufreq_register_notifier(&init_cpu_capacity_notifier,
+					 CPUFREQ_POLICY_NOTIFIER);
+}
+core_initcall(register_cpufreq_notifier);
+
+static void parsing_done_workfn(struct work_struct *work)
+{
+	cpufreq_unregister_notifier(&init_cpu_capacity_notifier,
+					 CPUFREQ_POLICY_NOTIFIER);
+}
+
+#else
+static int __init free_raw_capacity(void)
+{
+	kfree(raw_capacity);
+
+	return 0;
+}
+core_initcall(free_raw_capacity);
+#endif
+
 static int __init get_cpu_for_node(struct device_node *node)
 {
 	struct device_node *cpu_node;
@@ -34,6 +186,7 @@  static int __init get_cpu_for_node(struct device_node *node)
 
 	for_each_possible_cpu(cpu) {
 		if (of_get_cpu_node(cpu, NULL) == cpu_node) {
+			parse_cpu_capacity(cpu_node, cpu);
 			of_node_put(cpu_node);
 			return cpu;
 		}
@@ -178,13 +331,17 @@  static int __init parse_dt_topology(void)
 	 * cluster with restricted subnodes.
 	 */
 	map = of_get_child_by_name(cn, "cpu-map");
-	if (!map)
+	if (!map) {
+		cap_parsing_failed = true;
 		goto out;
+	}
 
 	ret = parse_cluster(map, 0);
 	if (ret != 0)
 		goto out_map;
 
+	normalize_cpu_capacity();
+
 	/*
 	 * Check that all cores are in the topology; the SMP code will
 	 * only mark cores described in the DT as possible.