2 * CPU subsystem support
5 #include <linux/kernel.h>
6 #include <linux/module.h>
7 #include <linux/init.h>
8 #include <linux/sched.h>
10 #include <linux/topology.h>
11 #include <linux/device.h>
12 #include <linux/node.h>
13 #include <linux/gfp.h>
14 #include <linux/slab.h>
15 #include <linux/percpu.h>
19 struct bus_type cpu_subsys = {
23 EXPORT_SYMBOL_GPL(cpu_subsys);
25 static DEFINE_PER_CPU(struct device *, cpu_sys_devices);
27 #ifdef CONFIG_HOTPLUG_CPU
28 static ssize_t show_online(struct device *dev,
29 struct device_attribute *attr,
32 struct cpu *cpu = container_of(dev, struct cpu, dev);
34 return sprintf(buf, "%u\n", !!cpu_online(cpu->dev.id));
37 static ssize_t __ref store_online(struct device *dev,
38 struct device_attribute *attr,
39 const char *buf, size_t count)
41 struct cpu *cpu = container_of(dev, struct cpu, dev);
44 cpu_hotplug_driver_lock();
47 ret = cpu_down(cpu->dev.id);
49 kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
52 ret = cpu_up(cpu->dev.id);
54 kobject_uevent(&dev->kobj, KOBJ_ONLINE);
59 cpu_hotplug_driver_unlock();
65 static DEVICE_ATTR(online, 0644, show_online, store_online);
67 static void __cpuinit register_cpu_control(struct cpu *cpu)
69 device_create_file(&cpu->dev, &dev_attr_online);
71 void unregister_cpu(struct cpu *cpu)
73 int logical_cpu = cpu->dev.id;
75 unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
77 device_remove_file(&cpu->dev, &dev_attr_online);
79 device_unregister(&cpu->dev);
80 per_cpu(cpu_sys_devices, logical_cpu) = NULL;
84 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
85 static ssize_t cpu_probe_store(struct device *dev,
86 struct device_attribute *attr,
90 return arch_cpu_probe(buf, count);
93 static ssize_t cpu_release_store(struct device *dev,
94 struct device_attribute *attr,
98 return arch_cpu_release(buf, count);
101 static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
102 static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
103 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
105 #else /* ... !CONFIG_HOTPLUG_CPU */
106 static inline void register_cpu_control(struct cpu *cpu)
109 #endif /* CONFIG_HOTPLUG_CPU */
112 #include <linux/kexec.h>
114 static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr,
117 struct cpu *cpu = container_of(dev, struct cpu, dev);
119 unsigned long long addr;
122 cpunum = cpu->dev.id;
125 * Might be reading other cpu's data based on which cpu read thread
126 * has been scheduled. But cpu data (memory) is allocated once during
127 * boot up and this data does not change there after. Hence this
128 * operation should be safe. No locking required.
130 addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
131 rc = sprintf(buf, "%Lx\n", addr);
134 static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL);
136 static ssize_t show_crash_notes_size(struct device *dev,
137 struct device_attribute *attr,
142 rc = sprintf(buf, "%lu\n", sizeof(note_buf_t));
145 static DEVICE_ATTR(crash_notes_size, 0400, show_crash_notes_size, NULL);
149 * Print cpu online, possible, present, and system maps
153 struct device_attribute attr;
154 const struct cpumask *const * const map;
157 static ssize_t show_cpus_attr(struct device *dev,
158 struct device_attribute *attr,
161 struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
162 int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map));
169 #define _CPU_ATTR(name, map) \
170 { __ATTR(name, 0444, show_cpus_attr, NULL), map }
172 /* Keep in sync with cpu_subsys_attrs */
173 static struct cpu_attr cpu_attrs[] = {
174 _CPU_ATTR(online, &cpu_online_mask),
175 _CPU_ATTR(possible, &cpu_possible_mask),
176 _CPU_ATTR(present, &cpu_present_mask),
180 * Print values for NR_CPUS and offlined cpus
182 static ssize_t print_cpus_kernel_max(struct device *dev,
183 struct device_attribute *attr, char *buf)
185 int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
188 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
190 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
191 unsigned int total_cpus;
193 static ssize_t print_cpus_offline(struct device *dev,
194 struct device_attribute *attr, char *buf)
196 int n = 0, len = PAGE_SIZE-2;
197 cpumask_var_t offline;
199 /* display offline cpus < nr_cpu_ids */
200 if (!alloc_cpumask_var(&offline, GFP_KERNEL))
202 cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
203 n = cpulist_scnprintf(buf, len, offline);
204 free_cpumask_var(offline);
206 /* display offline cpus >= nr_cpu_ids */
207 if (total_cpus && nr_cpu_ids < total_cpus) {
211 if (nr_cpu_ids == total_cpus-1)
212 n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
214 n += snprintf(&buf[n], len - n, "%d-%d",
215 nr_cpu_ids, total_cpus-1);
218 n += snprintf(&buf[n], len - n, "\n");
221 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
223 static void cpu_device_release(struct device *dev)
226 * This is an empty function to prevent the driver core from spitting a
227 * warning at us. Yes, I know this is directly opposite of what the
228 * documentation for the driver core and kobjects say, and the author
229 * of this code has already been publically ridiculed for doing
230 * something as foolish as this. However, at this point in time, it is
231 * the only way to handle the issue of statically allocated cpu
232 * devices. The different architectures will have their cpu device
233 * code reworked to properly handle this in the near future, so this
234 * function will then be changed to correctly free up the memory held
237 * Never copy this way of doing things, or you too will be made fun of
238 * on the linux-kernel list, you have been warned.
243 * register_cpu - Setup a sysfs device for a CPU.
244 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
245 * sysfs for this CPU.
246 * @num - CPU number to use when creating the device.
248 * Initialize and register the CPU device.
250 int __cpuinit register_cpu(struct cpu *cpu, int num)
254 cpu->node_id = cpu_to_node(num);
255 memset(&cpu->dev, 0x00, sizeof(struct device));
257 cpu->dev.bus = &cpu_subsys;
258 cpu->dev.release = cpu_device_release;
259 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
260 cpu->dev.bus->uevent = arch_cpu_uevent;
262 error = device_register(&cpu->dev);
263 if (!error && cpu->hotpluggable)
264 register_cpu_control(cpu);
266 per_cpu(cpu_sys_devices, num) = &cpu->dev;
268 register_cpu_under_node(num, cpu_to_node(num));
272 error = device_create_file(&cpu->dev, &dev_attr_crash_notes);
274 error = device_create_file(&cpu->dev,
275 &dev_attr_crash_notes_size);
280 struct device *get_cpu_device(unsigned cpu)
282 if (cpu < nr_cpu_ids && cpu_possible(cpu))
283 return per_cpu(cpu_sys_devices, cpu);
287 EXPORT_SYMBOL_GPL(get_cpu_device);
289 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
290 static DEVICE_ATTR(modalias, 0444, arch_print_cpu_modalias, NULL);
293 static struct attribute *cpu_root_attrs[] = {
294 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
295 &dev_attr_probe.attr,
296 &dev_attr_release.attr,
298 &cpu_attrs[0].attr.attr,
299 &cpu_attrs[1].attr.attr,
300 &cpu_attrs[2].attr.attr,
301 &dev_attr_kernel_max.attr,
302 &dev_attr_offline.attr,
303 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
304 &dev_attr_modalias.attr,
309 static struct attribute_group cpu_root_attr_group = {
310 .attrs = cpu_root_attrs,
313 static const struct attribute_group *cpu_root_attr_groups[] = {
314 &cpu_root_attr_group,
318 bool cpu_is_hotpluggable(unsigned cpu)
320 struct device *dev = get_cpu_device(cpu);
321 return dev && container_of(dev, struct cpu, dev)->hotpluggable;
323 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
325 #ifdef CONFIG_GENERIC_CPU_DEVICES
326 static DEFINE_PER_CPU(struct cpu, cpu_devices);
329 static void __init cpu_dev_register_generic(void)
331 #ifdef CONFIG_GENERIC_CPU_DEVICES
334 for_each_possible_cpu(i) {
335 if (register_cpu(&per_cpu(cpu_devices, i), i))
336 panic("Failed to register CPU device");
341 void __init cpu_dev_init(void)
343 if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
344 panic("Failed to register CPU subsystem");
346 cpu_dev_register_generic();