1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Arch specific cpu topology information
  4 *
  5 * Copyright (C) 2016, ARM Ltd.
  6 * Written by: Juri Lelli, ARM Ltd.
  7 */
  8
  9#include <linux/acpi.h>
 10#include <linux/arch_topology.h>
 11#include <linux/cpu.h>
 12#include <linux/cpufreq.h>
 13#include <linux/device.h>
 14#include <linux/of.h>
 15#include <linux/slab.h>
 16#include <linux/string.h>
 17#include <linux/sched/topology.h>
 18
 19DEFINE_PER_CPU(unsigned long, freq_scale) = SCHED_CAPACITY_SCALE;
 20
 21void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq,
 22			 unsigned long max_freq)
 23{
 24	unsigned long scale;
 25	int i;
 26
 27	scale = (cur_freq << SCHED_CAPACITY_SHIFT) / max_freq;
 28
 29	for_each_cpu(i, cpus)
 30		per_cpu(freq_scale, i) = scale;
 31}
 32
 33static DEFINE_MUTEX(cpu_scale_mutex);
 34DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;
 35
 36void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity)
 37{
 38	per_cpu(cpu_scale, cpu) = capacity;
 39}
 40
 41static ssize_t cpu_capacity_show(struct device *dev,
 42				 struct device_attribute *attr,
 43				 char *buf)
 44{
 45	struct cpu *cpu = container_of(dev, struct cpu, dev);
 46
 47	return sprintf(buf, "%lu\n", topology_get_cpu_scale(NULL, cpu->dev.id));
 48}
 49
 50static ssize_t cpu_capacity_store(struct device *dev,
 51				  struct device_attribute *attr,
 52				  const char *buf,
 53				  size_t count)
 54{
 55	struct cpu *cpu = container_of(dev, struct cpu, dev);
 56	int this_cpu = cpu->dev.id;
 57	int i;
 58	unsigned long new_capacity;
 59	ssize_t ret;
 60
 61	if (!count)
 62		return 0;
 63
 64	ret = kstrtoul(buf, 0, &new_capacity);
 65	if (ret)
 66		return ret;
 67	if (new_capacity > SCHED_CAPACITY_SCALE)
 68		return -EINVAL;
 69
 70	mutex_lock(&cpu_scale_mutex);
 71	for_each_cpu(i, &cpu_topology[this_cpu].core_sibling)
 72		topology_set_cpu_scale(i, new_capacity);
 73	mutex_unlock(&cpu_scale_mutex);
 74
 75	return count;
 76}
 77
 78static DEVICE_ATTR_RW(cpu_capacity);
 79
 80static int register_cpu_capacity_sysctl(void)
 81{
 82	int i;
 83	struct device *cpu;
 84
 85	for_each_possible_cpu(i) {
 86		cpu = get_cpu_device(i);
 87		if (!cpu) {
 88			pr_err("%s: too early to get CPU%d device!\n",
 89			       __func__, i);
 90			continue;
 91		}
 92		device_create_file(cpu, &dev_attr_cpu_capacity);
 93	}
 94
 95	return 0;
 96}
 97subsys_initcall(register_cpu_capacity_sysctl);
 98
 99static u32 capacity_scale;
100static u32 *raw_capacity;
101
102static int free_raw_capacity(void)
103{
104	kfree(raw_capacity);
105	raw_capacity = NULL;
106
107	return 0;
108}
109
110void topology_normalize_cpu_scale(void)
111{
112	u64 capacity;
113	int cpu;
114
115	if (!raw_capacity)
116		return;
117
118	pr_debug("cpu_capacity: capacity_scale=%u\n", capacity_scale);
119	mutex_lock(&cpu_scale_mutex);
120	for_each_possible_cpu(cpu) {
121		pr_debug("cpu_capacity: cpu=%d raw_capacity=%u\n",
122			 cpu, raw_capacity[cpu]);
123		capacity = (raw_capacity[cpu] << SCHED_CAPACITY_SHIFT)
124			/ capacity_scale;
125		topology_set_cpu_scale(cpu, capacity);
126		pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n",
127			cpu, topology_get_cpu_scale(NULL, cpu));
128	}
129	mutex_unlock(&cpu_scale_mutex);
130}
131
132bool __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu)
133{
134	static bool cap_parsing_failed;
135	int ret;
136	u32 cpu_capacity;
137
138	if (cap_parsing_failed)
139		return false;
140
141	ret = of_property_read_u32(cpu_node, "capacity-dmips-mhz",
142				   &cpu_capacity);
143	if (!ret) {
144		if (!raw_capacity) {
145			raw_capacity = kcalloc(num_possible_cpus(),
146					       sizeof(*raw_capacity),
147					       GFP_KERNEL);
148			if (!raw_capacity) {
149				pr_err("cpu_capacity: failed to allocate memory for raw capacities\n");
150				cap_parsing_failed = true;
151				return false;
152			}
153		}
154		capacity_scale = max(cpu_capacity, capacity_scale);
155		raw_capacity[cpu] = cpu_capacity;
156		pr_debug("cpu_capacity: %pOF cpu_capacity=%u (raw)\n",
157			cpu_node, raw_capacity[cpu]);
158	} else {
159		if (raw_capacity) {
160			pr_err("cpu_capacity: missing %pOF raw capacity\n",
161				cpu_node);
162			pr_err("cpu_capacity: partial information: fallback to 1024 for all CPUs\n");
163		}
164		cap_parsing_failed = true;
165		free_raw_capacity();
166	}
167
168	return !ret;
169}
170
171#ifdef CONFIG_CPU_FREQ
172static cpumask_var_t cpus_to_visit;
173static void parsing_done_workfn(struct work_struct *work);
174static DECLARE_WORK(parsing_done_work, parsing_done_workfn);
175
176static int
177init_cpu_capacity_callback(struct notifier_block *nb,
178			   unsigned long val,
179			   void *data)
180{
181	struct cpufreq_policy *policy = data;
182	int cpu;
183
184	if (!raw_capacity)
185		return 0;
186
187	if (val != CPUFREQ_NOTIFY)
188		return 0;
189
190	pr_debug("cpu_capacity: init cpu capacity for CPUs [%*pbl] (to_visit=%*pbl)\n",
191		 cpumask_pr_args(policy->related_cpus),
192		 cpumask_pr_args(cpus_to_visit));
193
194	cpumask_andnot(cpus_to_visit, cpus_to_visit, policy->related_cpus);
195
196	for_each_cpu(cpu, policy->related_cpus) {
197		raw_capacity[cpu] = topology_get_cpu_scale(NULL, cpu) *
198				    policy->cpuinfo.max_freq / 1000UL;
199		capacity_scale = max(raw_capacity[cpu], capacity_scale);
200	}
201
202	if (cpumask_empty(cpus_to_visit)) {
203		topology_normalize_cpu_scale();
204		free_raw_capacity();
205		pr_debug("cpu_capacity: parsing done\n");
206		schedule_work(&parsing_done_work);
207	}
208
209	return 0;
210}
211
212static struct notifier_block init_cpu_capacity_notifier = {
213	.notifier_call = init_cpu_capacity_callback,
214};
215
216static int __init register_cpufreq_notifier(void)
217{
218	int ret;
219
220	/*
221	 * on ACPI-based systems we need to use the default cpu capacity
222	 * until we have the necessary code to parse the cpu capacity, so
223	 * skip registering cpufreq notifier.
224	 */
225	if (!acpi_disabled || !raw_capacity)
226		return -EINVAL;
227
228	if (!alloc_cpumask_var(&cpus_to_visit, GFP_KERNEL)) {
229		pr_err("cpu_capacity: failed to allocate memory for cpus_to_visit\n");
230		return -ENOMEM;
231	}
232
233	cpumask_copy(cpus_to_visit, cpu_possible_mask);
234
235	ret = cpufreq_register_notifier(&init_cpu_capacity_notifier,
236					CPUFREQ_POLICY_NOTIFIER);
237
238	if (ret)
239		free_cpumask_var(cpus_to_visit);
240
241	return ret;
242}
243core_initcall(register_cpufreq_notifier);
244
245static void parsing_done_workfn(struct work_struct *work)
246{
247	cpufreq_unregister_notifier(&init_cpu_capacity_notifier,
248					 CPUFREQ_POLICY_NOTIFIER);
249	free_cpumask_var(cpus_to_visit);
250}
251
252#else
253core_initcall(free_raw_capacity);
254#endif