text: /*
   * Arch specific cpu topology information
   *
   * Copyright (C) 2016, ARM Ltd.
   * Written by: Juri Lelli, ARM Ltd.
   *
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * Released under the GPLv2 only.
   * SPDX-License-Identifier: GPL-2.0
   */
  
  #include <linux/acpi.h>
  #include <linux/arch_topology.h>
  #include <linux/cpu.h>
  #include <linux/cpufreq.h>
  #include <linux/device.h>
  #include <linux/of.h>
  #include <linux/slab.h>
  #include <linux/string.h>
  #include <linux/sched/topology.h>
  
  static DEFINE_MUTEX(cpu_scale_mutex);
  static DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;
  
  unsigned long topology_get_cpu_scale(struct sched_domain *sd, int cpu)
  {
  	return per_cpu(cpu_scale, cpu);
  }
  
  void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity)
  {
  	per_cpu(cpu_scale, cpu) = capacity;
  }
  
  static ssize_t cpu_capacity_show(struct device *dev,
  				 struct device_attribute *attr,
  				 char *buf)
  {
  	struct cpu *cpu = container_of(dev, struct cpu, dev);
  
  	return sprintf(buf, "%lu\n",
  			topology_get_cpu_scale(NULL, cpu->dev.id));
  }
  
  static ssize_t cpu_capacity_store(struct device *dev,
  				  struct device_attribute *attr,
  				  const char *buf,
  				  size_t count)
  {
  	struct cpu *cpu = container_of(dev, struct cpu, dev);
  	int this_cpu = cpu->dev.id;
  	int i;
  	unsigned long new_capacity;
  	ssize_t ret;
  
  	if (!count)
  		return 0;
  
  	ret = kstrtoul(buf, 0, &new_capacity);
  	if (ret)
  		return ret;
  	if (new_capacity > SCHED_CAPACITY_SCALE)
  		return -EINVAL;
  
  	mutex_lock(&cpu_scale_mutex);
  	for_each_cpu(i, &cpu_topology[this_cpu].core_sibling)
  		topology_set_cpu_scale(i, new_capacity);
  	mutex_unlock(&cpu_scale_mutex);
  
  	return count;
  }
  
  static DEVICE_ATTR_RW(cpu_capacity);
  
  static int register_cpu_capacity_sysctl(void)
  {
  	int i;
  	struct device *cpu;
  
  	for_each_possible_cpu(i) {
  		cpu = get_cpu_device(i);
  		if (!cpu) {
  			pr_err("%s: too early to get CPU%d device!\n",
  			       __func__, i);
  			continue;
  		}
  		device_create_file(cpu, &dev_attr_cpu_capacity);
  	}
  
  	return 0;
  }
  subsys_initcall(register_cpu_capacity_sysctl);
  
  static u32 capacity_scale;
  static u32 *raw_capacity;
  static bool cap_parsing_failed;
  
  void topology_normalize_cpu_scale(void)
  {
  	u64 capacity;
  	int cpu;
  
  	if (!raw_capacity || cap_parsing_failed)
  		return;
  
  	pr_debug("cpu_capacity: capacity_scale=%u\n", capacity_scale);
  	mutex_lock(&cpu_scale_mutex);
  	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;
  		topology_set_cpu_scale(cpu, capacity);
  		pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n",
  			cpu, topology_get_cpu_scale(NULL, cpu));
  	}
  	mutex_unlock(&cpu_scale_mutex);
  }
  
  int __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu)
  {
  	int ret = 1;
  	u32 cpu_capacity;
  
  	if (cap_parsing_failed)
  		return !ret;
  
  	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 0;
  			}
  		}
  		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);
  	}
  
  	return !ret;
  }
  
  #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] = topology_get_cpu_scale(NULL, cpu) *
  					    policy->cpuinfo.max_freq / 1000UL;
  			capacity_scale = max(raw_capacity[cpu], capacity_scale);
  		}
  		if (cpumask_empty(cpus_to_visit)) {
  			topology_normalize_cpu_scale();
  			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)
  {
  	/*
  	 * on ACPI-based systems we need to use the default cpu capacity
  	 * until we have the necessary code to parse the cpu capacity, so
  	 * skip registering cpufreq notifier.
  	 */
  	if (!acpi_disabled || !raw_capacity)
  		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
  