2 * CPU subsystem support
5 #include <linux/module.h>
6 #include <linux/init.h>
7 #include <linux/sched.h>
9 #include <linux/topology.h>
10 #include <linux/device.h>
11 #include <linux/node.h>
12 #include <linux/gfp.h>
16 struct bus_type cpu_subsys = {
20 EXPORT_SYMBOL_GPL(cpu_subsys);
22 static DEFINE_PER_CPU(struct device *, cpu_sys_devices);
24 #ifdef CONFIG_HOTPLUG_CPU
25 static ssize_t show_online(struct device *dev,
26 struct device_attribute *attr,
29 struct cpu *cpu = container_of(dev, struct cpu, dev);
31 return sprintf(buf, "%u\n", !!cpu_online(cpu->dev.id));
34 static ssize_t __ref store_online(struct device *dev,
35 struct device_attribute *attr,
36 const char *buf, size_t count)
38 struct cpu *cpu = container_of(dev, struct cpu, dev);
41 cpu_hotplug_driver_lock();
44 ret = cpu_down(cpu->dev.id);
46 kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
49 ret = cpu_up(cpu->dev.id);
51 kobject_uevent(&dev->kobj, KOBJ_ONLINE);
56 cpu_hotplug_driver_unlock();
62 static DEVICE_ATTR(online, 0644, show_online, store_online);
64 static void __cpuinit register_cpu_control(struct cpu *cpu)
66 device_create_file(&cpu->dev, &dev_attr_online);
68 void unregister_cpu(struct cpu *cpu)
70 int logical_cpu = cpu->dev.id;
72 unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
74 device_remove_file(&cpu->dev, &dev_attr_online);
76 device_unregister(&cpu->dev);
77 per_cpu(cpu_sys_devices, logical_cpu) = NULL;
81 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
82 static ssize_t cpu_probe_store(struct device *dev,
83 struct device_attribute *attr,
87 return arch_cpu_probe(buf, count);
90 static ssize_t cpu_release_store(struct device *dev,
91 struct device_attribute *attr,
95 return arch_cpu_release(buf, count);
98 static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
99 static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
100 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
102 #else /* ... !CONFIG_HOTPLUG_CPU */
103 static inline void register_cpu_control(struct cpu *cpu)
106 #endif /* CONFIG_HOTPLUG_CPU */
109 #include <linux/kexec.h>
111 static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr,
114 struct cpu *cpu = container_of(dev, struct cpu, dev);
116 unsigned long long addr;
119 cpunum = cpu->dev.id;
122 * Might be reading other cpu's data based on which cpu read thread
123 * has been scheduled. But cpu data (memory) is allocated once during
124 * boot up and this data does not change there after. Hence this
125 * operation should be safe. No locking required.
127 addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
128 rc = sprintf(buf, "%Lx\n", addr);
131 static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL);
135 * Print cpu online, possible, present, and system maps
139 struct device_attribute attr;
140 const struct cpumask *const * const map;
143 static ssize_t show_cpus_attr(struct device *dev,
144 struct device_attribute *attr,
147 struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
148 int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map));
155 #define _CPU_ATTR(name, map) \
156 { __ATTR(name, 0444, show_cpus_attr, NULL), map }
158 /* Keep in sync with cpu_subsys_attrs */
159 static struct cpu_attr cpu_attrs[] = {
160 _CPU_ATTR(online, &cpu_online_mask),
161 _CPU_ATTR(possible, &cpu_possible_mask),
162 _CPU_ATTR(present, &cpu_present_mask),
166 * Print values for NR_CPUS and offlined cpus
168 static ssize_t print_cpus_kernel_max(struct device *dev,
169 struct device_attribute *attr, char *buf)
171 int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
174 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
176 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
177 unsigned int total_cpus;
179 static ssize_t print_cpus_offline(struct device *dev,
180 struct device_attribute *attr, char *buf)
182 int n = 0, len = PAGE_SIZE-2;
183 cpumask_var_t offline;
185 /* display offline cpus < nr_cpu_ids */
186 if (!alloc_cpumask_var(&offline, GFP_KERNEL))
188 cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
189 n = cpulist_scnprintf(buf, len, offline);
190 free_cpumask_var(offline);
192 /* display offline cpus >= nr_cpu_ids */
193 if (total_cpus && nr_cpu_ids < total_cpus) {
197 if (nr_cpu_ids == total_cpus-1)
198 n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
200 n += snprintf(&buf[n], len - n, "%d-%d",
201 nr_cpu_ids, total_cpus-1);
204 n += snprintf(&buf[n], len - n, "\n");
207 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
210 * register_cpu - Setup a sysfs device for a CPU.
211 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
212 * sysfs for this CPU.
213 * @num - CPU number to use when creating the device.
215 * Initialize and register the CPU device.
217 int __cpuinit register_cpu(struct cpu *cpu, int num)
221 cpu->node_id = cpu_to_node(num);
223 cpu->dev.bus = &cpu_subsys;
224 error = device_register(&cpu->dev);
225 if (!error && cpu->hotpluggable)
226 register_cpu_control(cpu);
228 per_cpu(cpu_sys_devices, num) = &cpu->dev;
230 register_cpu_under_node(num, cpu_to_node(num));
234 error = device_create_file(&cpu->dev, &dev_attr_crash_notes);
239 struct device *get_cpu_device(unsigned cpu)
241 if (cpu < nr_cpu_ids && cpu_possible(cpu))
242 return per_cpu(cpu_sys_devices, cpu);
246 EXPORT_SYMBOL_GPL(get_cpu_device);
248 static struct attribute *cpu_root_attrs[] = {
249 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
250 &dev_attr_probe.attr,
251 &dev_attr_release.attr,
253 &cpu_attrs[0].attr.attr,
254 &cpu_attrs[1].attr.attr,
255 &cpu_attrs[2].attr.attr,
256 &dev_attr_kernel_max.attr,
257 &dev_attr_offline.attr,
261 static struct attribute_group cpu_root_attr_group = {
262 .attrs = cpu_root_attrs,
265 static const struct attribute_group *cpu_root_attr_groups[] = {
266 &cpu_root_attr_group,
270 int __init cpu_dev_init(void)
274 err = subsys_system_register(&cpu_subsys, cpu_root_attr_groups);
278 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
279 err = sched_create_sysfs_power_savings_entries(cpu_subsys.dev_root);