0ca44682f2b939bbda7d3d6e14a6ecc5a26330ee
[muen/linux.git] / drivers / base / arch_topology.c
1 /*
2  * Arch specific cpu topology information
3  *
4  * Copyright (C) 2016, ARM Ltd.
5  * Written by: Juri Lelli, ARM Ltd.
6  *
7  * This file is subject to the terms and conditions of the GNU General Public
8  * License.  See the file "COPYING" in the main directory of this archive
9  * for more details.
10  *
11  * Released under the GPLv2 only.
12  * SPDX-License-Identifier: GPL-2.0
13  */
14
15 #include <linux/acpi.h>
16 #include <linux/arch_topology.h>
17 #include <linux/cpu.h>
18 #include <linux/cpufreq.h>
19 #include <linux/device.h>
20 #include <linux/of.h>
21 #include <linux/slab.h>
22 #include <linux/string.h>
23 #include <linux/sched/topology.h>
24
25 static DEFINE_MUTEX(cpu_scale_mutex);
26 static DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;
27
28 unsigned long topology_get_cpu_scale(struct sched_domain *sd, int cpu)
29 {
30         return per_cpu(cpu_scale, cpu);
31 }
32
33 void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity)
34 {
35         per_cpu(cpu_scale, cpu) = capacity;
36 }
37
38 static ssize_t cpu_capacity_show(struct device *dev,
39                                  struct device_attribute *attr,
40                                  char *buf)
41 {
42         struct cpu *cpu = container_of(dev, struct cpu, dev);
43
44         return sprintf(buf, "%lu\n", topology_get_cpu_scale(NULL, cpu->dev.id));
45 }
46
47 static ssize_t cpu_capacity_store(struct device *dev,
48                                   struct device_attribute *attr,
49                                   const char *buf,
50                                   size_t count)
51 {
52         struct cpu *cpu = container_of(dev, struct cpu, dev);
53         int this_cpu = cpu->dev.id;
54         int i;
55         unsigned long new_capacity;
56         ssize_t ret;
57
58         if (!count)
59                 return 0;
60
61         ret = kstrtoul(buf, 0, &new_capacity);
62         if (ret)
63                 return ret;
64         if (new_capacity > SCHED_CAPACITY_SCALE)
65                 return -EINVAL;
66
67         mutex_lock(&cpu_scale_mutex);
68         for_each_cpu(i, &cpu_topology[this_cpu].core_sibling)
69                 topology_set_cpu_scale(i, new_capacity);
70         mutex_unlock(&cpu_scale_mutex);
71
72         return count;
73 }
74
75 static DEVICE_ATTR_RW(cpu_capacity);
76
77 static int register_cpu_capacity_sysctl(void)
78 {
79         int i;
80         struct device *cpu;
81
82         for_each_possible_cpu(i) {
83                 cpu = get_cpu_device(i);
84                 if (!cpu) {
85                         pr_err("%s: too early to get CPU%d device!\n",
86                                __func__, i);
87                         continue;
88                 }
89                 device_create_file(cpu, &dev_attr_cpu_capacity);
90         }
91
92         return 0;
93 }
94 subsys_initcall(register_cpu_capacity_sysctl);
95
96 static u32 capacity_scale;
97 static u32 *raw_capacity;
98
99 static int free_raw_capacity(void)
100 {
101         kfree(raw_capacity);
102         raw_capacity = NULL;
103
104         return 0;
105 }
106
107 void topology_normalize_cpu_scale(void)
108 {
109         u64 capacity;
110         int cpu;
111
112         if (!raw_capacity)
113                 return;
114
115         pr_debug("cpu_capacity: capacity_scale=%u\n", capacity_scale);
116         mutex_lock(&cpu_scale_mutex);
117         for_each_possible_cpu(cpu) {
118                 pr_debug("cpu_capacity: cpu=%d raw_capacity=%u\n",
119                          cpu, raw_capacity[cpu]);
120                 capacity = (raw_capacity[cpu] << SCHED_CAPACITY_SHIFT)
121                         / capacity_scale;
122                 topology_set_cpu_scale(cpu, capacity);
123                 pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n",
124                         cpu, topology_get_cpu_scale(NULL, cpu));
125         }
126         mutex_unlock(&cpu_scale_mutex);
127 }
128
129 bool __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu)
130 {
131         static bool cap_parsing_failed;
132         int ret;
133         u32 cpu_capacity;
134
135         if (cap_parsing_failed)
136                 return false;
137
138         ret = of_property_read_u32(cpu_node, "capacity-dmips-mhz",
139                                    &cpu_capacity);
140         if (!ret) {
141                 if (!raw_capacity) {
142                         raw_capacity = kcalloc(num_possible_cpus(),
143                                                sizeof(*raw_capacity),
144                                                GFP_KERNEL);
145                         if (!raw_capacity) {
146                                 pr_err("cpu_capacity: failed to allocate memory for raw capacities\n");
147                                 cap_parsing_failed = true;
148                                 return false;
149                         }
150                 }
151                 capacity_scale = max(cpu_capacity, capacity_scale);
152                 raw_capacity[cpu] = cpu_capacity;
153                 pr_debug("cpu_capacity: %pOF cpu_capacity=%u (raw)\n",
154                         cpu_node, raw_capacity[cpu]);
155         } else {
156                 if (raw_capacity) {
157                         pr_err("cpu_capacity: missing %pOF raw capacity\n",
158                                 cpu_node);
159                         pr_err("cpu_capacity: partial information: fallback to 1024 for all CPUs\n");
160                 }
161                 cap_parsing_failed = true;
162                 free_raw_capacity();
163         }
164
165         return !ret;
166 }
167
168 #ifdef CONFIG_CPU_FREQ
169 static cpumask_var_t cpus_to_visit __initdata;
170 static void __init parsing_done_workfn(struct work_struct *work);
171 static __initdata DECLARE_WORK(parsing_done_work, parsing_done_workfn);
172
173 static int __init
174 init_cpu_capacity_callback(struct notifier_block *nb,
175                            unsigned long val,
176                            void *data)
177 {
178         struct cpufreq_policy *policy = data;
179         int cpu;
180
181         if (!raw_capacity)
182                 return 0;
183
184         if (val != CPUFREQ_NOTIFY)
185                 return 0;
186
187         pr_debug("cpu_capacity: init cpu capacity for CPUs [%*pbl] (to_visit=%*pbl)\n",
188                  cpumask_pr_args(policy->related_cpus),
189                  cpumask_pr_args(cpus_to_visit));
190
191         cpumask_andnot(cpus_to_visit, cpus_to_visit, policy->related_cpus);
192
193         for_each_cpu(cpu, policy->related_cpus) {
194                 raw_capacity[cpu] = topology_get_cpu_scale(NULL, cpu) *
195                                     policy->cpuinfo.max_freq / 1000UL;
196                 capacity_scale = max(raw_capacity[cpu], capacity_scale);
197         }
198
199         if (cpumask_empty(cpus_to_visit)) {
200                 topology_normalize_cpu_scale();
201                 free_raw_capacity();
202                 pr_debug("cpu_capacity: parsing done\n");
203                 schedule_work(&parsing_done_work);
204         }
205
206         return 0;
207 }
208
209 static struct notifier_block init_cpu_capacity_notifier __initdata = {
210         .notifier_call = init_cpu_capacity_callback,
211 };
212
213 static int __init register_cpufreq_notifier(void)
214 {
215         /*
216          * on ACPI-based systems we need to use the default cpu capacity
217          * until we have the necessary code to parse the cpu capacity, so
218          * skip registering cpufreq notifier.
219          */
220         if (!acpi_disabled || !raw_capacity)
221                 return -EINVAL;
222
223         if (!alloc_cpumask_var(&cpus_to_visit, GFP_KERNEL)) {
224                 pr_err("cpu_capacity: failed to allocate memory for cpus_to_visit\n");
225                 return -ENOMEM;
226         }
227
228         cpumask_copy(cpus_to_visit, cpu_possible_mask);
229
230         return cpufreq_register_notifier(&init_cpu_capacity_notifier,
231                                          CPUFREQ_POLICY_NOTIFIER);
232 }
233 core_initcall(register_cpufreq_notifier);
234
235 static void __init parsing_done_workfn(struct work_struct *work)
236 {
237         cpufreq_unregister_notifier(&init_cpu_capacity_notifier,
238                                          CPUFREQ_POLICY_NOTIFIER);
239 }
240
241 #else
242 core_initcall(free_raw_capacity);
243 #endif