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>
16 #include <linux/cpufeature.h>
20 struct bus_type cpu_subsys = {
24 EXPORT_SYMBOL_GPL(cpu_subsys);
26 static DEFINE_PER_CPU(struct device *, cpu_sys_devices);
28 #ifdef CONFIG_HOTPLUG_CPU
29 static void change_cpu_under_node(struct cpu *cpu,
30 unsigned int from_nid, unsigned int to_nid)
32 int cpuid = cpu->dev.id;
33 unregister_cpu_under_node(cpuid, from_nid);
34 register_cpu_under_node(cpuid, to_nid);
35 cpu->node_id = to_nid;
38 static ssize_t show_online(struct device *dev,
39 struct device_attribute *attr,
42 struct cpu *cpu = container_of(dev, struct cpu, dev);
44 return sprintf(buf, "%u\n", !!cpu_online(cpu->dev.id));
47 static ssize_t __ref store_online(struct device *dev,
48 struct device_attribute *attr,
49 const char *buf, size_t count)
51 struct cpu *cpu = container_of(dev, struct cpu, dev);
52 int cpuid = cpu->dev.id;
56 cpu_hotplug_driver_lock();
59 ret = cpu_down(cpuid);
61 kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
64 from_nid = cpu_to_node(cpuid);
68 * When hot adding memory to memoryless node and enabling a cpu
69 * on the node, node number of the cpu may internally change.
71 to_nid = cpu_to_node(cpuid);
72 if (from_nid != to_nid)
73 change_cpu_under_node(cpu, from_nid, to_nid);
76 kobject_uevent(&dev->kobj, KOBJ_ONLINE);
81 cpu_hotplug_driver_unlock();
87 static DEVICE_ATTR(online, 0644, show_online, store_online);
89 static void __cpuinit register_cpu_control(struct cpu *cpu)
91 device_create_file(&cpu->dev, &dev_attr_online);
93 void unregister_cpu(struct cpu *cpu)
95 int logical_cpu = cpu->dev.id;
97 unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
99 device_remove_file(&cpu->dev, &dev_attr_online);
101 device_unregister(&cpu->dev);
102 per_cpu(cpu_sys_devices, logical_cpu) = NULL;
106 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
107 static ssize_t cpu_probe_store(struct device *dev,
108 struct device_attribute *attr,
112 return arch_cpu_probe(buf, count);
115 static ssize_t cpu_release_store(struct device *dev,
116 struct device_attribute *attr,
120 return arch_cpu_release(buf, count);
123 static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
124 static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
125 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
127 #else /* ... !CONFIG_HOTPLUG_CPU */
128 static inline void register_cpu_control(struct cpu *cpu)
131 #endif /* CONFIG_HOTPLUG_CPU */
134 #include <linux/kexec.h>
136 static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr,
139 struct cpu *cpu = container_of(dev, struct cpu, dev);
141 unsigned long long addr;
144 cpunum = cpu->dev.id;
147 * Might be reading other cpu's data based on which cpu read thread
148 * has been scheduled. But cpu data (memory) is allocated once during
149 * boot up and this data does not change there after. Hence this
150 * operation should be safe. No locking required.
152 addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
153 rc = sprintf(buf, "%Lx\n", addr);
156 static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL);
158 static ssize_t show_crash_notes_size(struct device *dev,
159 struct device_attribute *attr,
164 rc = sprintf(buf, "%zu\n", sizeof(note_buf_t));
167 static DEVICE_ATTR(crash_notes_size, 0400, show_crash_notes_size, NULL);
171 * Print cpu online, possible, present, and system maps
175 struct device_attribute attr;
176 const struct cpumask *const * const map;
179 static ssize_t show_cpus_attr(struct device *dev,
180 struct device_attribute *attr,
183 struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
184 int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map));
191 #define _CPU_ATTR(name, map) \
192 { __ATTR(name, 0444, show_cpus_attr, NULL), map }
194 /* Keep in sync with cpu_subsys_attrs */
195 static struct cpu_attr cpu_attrs[] = {
196 _CPU_ATTR(online, &cpu_online_mask),
197 _CPU_ATTR(possible, &cpu_possible_mask),
198 _CPU_ATTR(present, &cpu_present_mask),
202 * Print values for NR_CPUS and offlined cpus
204 static ssize_t print_cpus_kernel_max(struct device *dev,
205 struct device_attribute *attr, char *buf)
207 int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
210 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
212 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
213 unsigned int total_cpus;
215 static ssize_t print_cpus_offline(struct device *dev,
216 struct device_attribute *attr, char *buf)
218 int n = 0, len = PAGE_SIZE-2;
219 cpumask_var_t offline;
221 /* display offline cpus < nr_cpu_ids */
222 if (!alloc_cpumask_var(&offline, GFP_KERNEL))
224 cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
225 n = cpulist_scnprintf(buf, len, offline);
226 free_cpumask_var(offline);
228 /* display offline cpus >= nr_cpu_ids */
229 if (total_cpus && nr_cpu_ids < total_cpus) {
233 if (nr_cpu_ids == total_cpus-1)
234 n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
236 n += snprintf(&buf[n], len - n, "%d-%d",
237 nr_cpu_ids, total_cpus-1);
240 n += snprintf(&buf[n], len - n, "\n");
243 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
245 static void cpu_device_release(struct device *dev)
248 * This is an empty function to prevent the driver core from spitting a
249 * warning at us. Yes, I know this is directly opposite of what the
250 * documentation for the driver core and kobjects say, and the author
251 * of this code has already been publically ridiculed for doing
252 * something as foolish as this. However, at this point in time, it is
253 * the only way to handle the issue of statically allocated cpu
254 * devices. The different architectures will have their cpu device
255 * code reworked to properly handle this in the near future, so this
256 * function will then be changed to correctly free up the memory held
259 * Never copy this way of doing things, or you too will be made fun of
260 * on the linux-kernel list, you have been warned.
264 #ifdef CONFIG_HAVE_CPU_AUTOPROBE
265 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
266 static ssize_t print_cpu_modalias(struct device *dev,
267 struct device_attribute *attr,
273 n = sprintf(buf, "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:",
274 CPU_FEATURE_TYPEVAL);
276 for (i = 0; i < MAX_CPU_FEATURES; i++)
277 if (cpu_have_feature(i)) {
278 if (PAGE_SIZE < n + sizeof(",XXXX\n")) {
279 WARN(1, "CPU features overflow page\n");
282 n += sprintf(&buf[n], ",%04X", i);
288 #define print_cpu_modalias arch_print_cpu_modalias
291 static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env)
293 char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
295 print_cpu_modalias(NULL, NULL, buf);
296 add_uevent_var(env, "MODALIAS=%s", buf);
304 * register_cpu - Setup a sysfs device for a CPU.
305 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
306 * sysfs for this CPU.
307 * @num - CPU number to use when creating the device.
309 * Initialize and register the CPU device.
311 int __cpuinit register_cpu(struct cpu *cpu, int num)
315 cpu->node_id = cpu_to_node(num);
316 memset(&cpu->dev, 0x00, sizeof(struct device));
318 cpu->dev.bus = &cpu_subsys;
319 cpu->dev.release = cpu_device_release;
320 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
321 cpu->dev.bus->uevent = cpu_uevent;
323 error = device_register(&cpu->dev);
324 if (!error && cpu->hotpluggable)
325 register_cpu_control(cpu);
327 per_cpu(cpu_sys_devices, num) = &cpu->dev;
329 register_cpu_under_node(num, cpu_to_node(num));
333 error = device_create_file(&cpu->dev, &dev_attr_crash_notes);
335 error = device_create_file(&cpu->dev,
336 &dev_attr_crash_notes_size);
341 struct device *get_cpu_device(unsigned cpu)
343 if (cpu < nr_cpu_ids && cpu_possible(cpu))
344 return per_cpu(cpu_sys_devices, cpu);
348 EXPORT_SYMBOL_GPL(get_cpu_device);
350 #ifdef CONFIG_HAVE_CPU_AUTOPROBE
351 static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL);
354 static struct attribute *cpu_root_attrs[] = {
355 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
356 &dev_attr_probe.attr,
357 &dev_attr_release.attr,
359 &cpu_attrs[0].attr.attr,
360 &cpu_attrs[1].attr.attr,
361 &cpu_attrs[2].attr.attr,
362 &dev_attr_kernel_max.attr,
363 &dev_attr_offline.attr,
364 #ifdef CONFIG_HAVE_CPU_AUTOPROBE
365 &dev_attr_modalias.attr,
370 static struct attribute_group cpu_root_attr_group = {
371 .attrs = cpu_root_attrs,
374 static const struct attribute_group *cpu_root_attr_groups[] = {
375 &cpu_root_attr_group,
379 bool cpu_is_hotpluggable(unsigned cpu)
381 struct device *dev = get_cpu_device(cpu);
382 return dev && container_of(dev, struct cpu, dev)->hotpluggable;
384 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
386 #ifdef CONFIG_GENERIC_CPU_DEVICES
387 static DEFINE_PER_CPU(struct cpu, cpu_devices);
390 static void __init cpu_dev_register_generic(void)
392 #ifdef CONFIG_GENERIC_CPU_DEVICES
395 for_each_possible_cpu(i) {
396 if (register_cpu(&per_cpu(cpu_devices, i), i))
397 panic("Failed to register CPU device");
402 void __init cpu_dev_init(void)
404 if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
405 panic("Failed to register CPU subsystem");
407 cpu_dev_register_generic();