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/acpi.h>
18 #include <linux/cpufeature.h>
22 struct bus_type cpu_subsys = {
26 EXPORT_SYMBOL_GPL(cpu_subsys);
28 static DEFINE_PER_CPU(struct device *, cpu_sys_devices);
30 #ifdef CONFIG_HOTPLUG_CPU
31 static void change_cpu_under_node(struct cpu *cpu,
32 unsigned int from_nid, unsigned int to_nid)
34 int cpuid = cpu->dev.id;
35 unregister_cpu_under_node(cpuid, from_nid);
36 register_cpu_under_node(cpuid, to_nid);
37 cpu->node_id = to_nid;
40 static ssize_t show_online(struct device *dev,
41 struct device_attribute *attr,
44 struct cpu *cpu = container_of(dev, struct cpu, dev);
46 return sprintf(buf, "%u\n", !!cpu_online(cpu->dev.id));
49 static ssize_t __ref store_online(struct device *dev,
50 struct device_attribute *attr,
51 const char *buf, size_t count)
53 struct cpu *cpu = container_of(dev, struct cpu, dev);
54 int cpuid = cpu->dev.id;
58 cpu_hotplug_driver_lock();
61 ret = cpu_down(cpuid);
63 kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
66 from_nid = cpu_to_node(cpuid);
70 * When hot adding memory to memoryless node and enabling a cpu
71 * on the node, node number of the cpu may internally change.
73 to_nid = cpu_to_node(cpuid);
74 if (from_nid != to_nid)
75 change_cpu_under_node(cpu, from_nid, to_nid);
78 kobject_uevent(&dev->kobj, KOBJ_ONLINE);
83 cpu_hotplug_driver_unlock();
89 static DEVICE_ATTR(online, 0644, show_online, store_online);
91 static void __cpuinit register_cpu_control(struct cpu *cpu)
93 device_create_file(&cpu->dev, &dev_attr_online);
95 void unregister_cpu(struct cpu *cpu)
97 int logical_cpu = cpu->dev.id;
99 unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
101 device_remove_file(&cpu->dev, &dev_attr_online);
103 device_unregister(&cpu->dev);
104 per_cpu(cpu_sys_devices, logical_cpu) = NULL;
108 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
109 static ssize_t cpu_probe_store(struct device *dev,
110 struct device_attribute *attr,
114 return arch_cpu_probe(buf, count);
117 static ssize_t cpu_release_store(struct device *dev,
118 struct device_attribute *attr,
122 return arch_cpu_release(buf, count);
125 static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
126 static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
127 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
129 #else /* ... !CONFIG_HOTPLUG_CPU */
130 static inline void register_cpu_control(struct cpu *cpu)
133 #endif /* CONFIG_HOTPLUG_CPU */
136 #include <linux/kexec.h>
138 static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr,
141 struct cpu *cpu = container_of(dev, struct cpu, dev);
143 unsigned long long addr;
146 cpunum = cpu->dev.id;
149 * Might be reading other cpu's data based on which cpu read thread
150 * has been scheduled. But cpu data (memory) is allocated once during
151 * boot up and this data does not change there after. Hence this
152 * operation should be safe. No locking required.
154 addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
155 rc = sprintf(buf, "%Lx\n", addr);
158 static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL);
160 static ssize_t show_crash_notes_size(struct device *dev,
161 struct device_attribute *attr,
166 rc = sprintf(buf, "%zu\n", sizeof(note_buf_t));
169 static DEVICE_ATTR(crash_notes_size, 0400, show_crash_notes_size, NULL);
173 * Print cpu online, possible, present, and system maps
177 struct device_attribute attr;
178 const struct cpumask *const * const map;
181 static ssize_t show_cpus_attr(struct device *dev,
182 struct device_attribute *attr,
185 struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
186 int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map));
193 #define _CPU_ATTR(name, map) \
194 { __ATTR(name, 0444, show_cpus_attr, NULL), map }
196 /* Keep in sync with cpu_subsys_attrs */
197 static struct cpu_attr cpu_attrs[] = {
198 _CPU_ATTR(online, &cpu_online_mask),
199 _CPU_ATTR(possible, &cpu_possible_mask),
200 _CPU_ATTR(present, &cpu_present_mask),
204 * Print values for NR_CPUS and offlined cpus
206 static ssize_t print_cpus_kernel_max(struct device *dev,
207 struct device_attribute *attr, char *buf)
209 int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
212 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
214 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
215 unsigned int total_cpus;
217 static ssize_t print_cpus_offline(struct device *dev,
218 struct device_attribute *attr, char *buf)
220 int n = 0, len = PAGE_SIZE-2;
221 cpumask_var_t offline;
223 /* display offline cpus < nr_cpu_ids */
224 if (!alloc_cpumask_var(&offline, GFP_KERNEL))
226 cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
227 n = cpulist_scnprintf(buf, len, offline);
228 free_cpumask_var(offline);
230 /* display offline cpus >= nr_cpu_ids */
231 if (total_cpus && nr_cpu_ids < total_cpus) {
235 if (nr_cpu_ids == total_cpus-1)
236 n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
238 n += snprintf(&buf[n], len - n, "%d-%d",
239 nr_cpu_ids, total_cpus-1);
242 n += snprintf(&buf[n], len - n, "\n");
245 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
247 static void cpu_device_release(struct device *dev)
250 * This is an empty function to prevent the driver core from spitting a
251 * warning at us. Yes, I know this is directly opposite of what the
252 * documentation for the driver core and kobjects say, and the author
253 * of this code has already been publically ridiculed for doing
254 * something as foolish as this. However, at this point in time, it is
255 * the only way to handle the issue of statically allocated cpu
256 * devices. The different architectures will have their cpu device
257 * code reworked to properly handle this in the near future, so this
258 * function will then be changed to correctly free up the memory held
261 * Never copy this way of doing things, or you too will be made fun of
262 * on the linux-kernel list, you have been warned.
266 #ifdef CONFIG_HAVE_CPU_AUTOPROBE
267 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
268 static ssize_t print_cpu_modalias(struct device *dev,
269 struct device_attribute *attr,
275 n = sprintf(buf, "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:",
276 CPU_FEATURE_TYPEVAL);
278 for (i = 0; i < MAX_CPU_FEATURES; i++)
279 if (cpu_have_feature(i)) {
280 if (PAGE_SIZE < n + sizeof(",XXXX\n")) {
281 WARN(1, "CPU features overflow page\n");
284 n += sprintf(&buf[n], ",%04X", i);
290 #define print_cpu_modalias arch_print_cpu_modalias
293 static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env)
295 char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
297 print_cpu_modalias(NULL, NULL, buf);
298 add_uevent_var(env, "MODALIAS=%s", buf);
306 * register_cpu - Setup a sysfs device for a CPU.
307 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
308 * sysfs for this CPU.
309 * @num - CPU number to use when creating the device.
311 * Initialize and register the CPU device.
313 int __cpuinit register_cpu(struct cpu *cpu, int num)
317 cpu->node_id = cpu_to_node(num);
318 memset(&cpu->dev, 0x00, sizeof(struct device));
320 cpu->dev.bus = &cpu_subsys;
321 cpu->dev.release = cpu_device_release;
322 cpu->dev.of_node = of_get_cpu_node(num, NULL);
323 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
324 cpu->dev.bus->uevent = cpu_uevent;
326 error = device_register(&cpu->dev);
327 if (!error && cpu->hotpluggable)
328 register_cpu_control(cpu);
330 per_cpu(cpu_sys_devices, num) = &cpu->dev;
332 register_cpu_under_node(num, cpu_to_node(num));
336 error = device_create_file(&cpu->dev, &dev_attr_crash_notes);
338 error = device_create_file(&cpu->dev,
339 &dev_attr_crash_notes_size);
344 struct device *get_cpu_device(unsigned cpu)
346 if (cpu < nr_cpu_ids && cpu_possible(cpu))
347 return per_cpu(cpu_sys_devices, cpu);
351 EXPORT_SYMBOL_GPL(get_cpu_device);
353 #ifdef CONFIG_HAVE_CPU_AUTOPROBE
354 static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL);
357 static struct attribute *cpu_root_attrs[] = {
358 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
359 &dev_attr_probe.attr,
360 &dev_attr_release.attr,
362 &cpu_attrs[0].attr.attr,
363 &cpu_attrs[1].attr.attr,
364 &cpu_attrs[2].attr.attr,
365 &dev_attr_kernel_max.attr,
366 &dev_attr_offline.attr,
367 #ifdef CONFIG_HAVE_CPU_AUTOPROBE
368 &dev_attr_modalias.attr,
373 static struct attribute_group cpu_root_attr_group = {
374 .attrs = cpu_root_attrs,
377 static const struct attribute_group *cpu_root_attr_groups[] = {
378 &cpu_root_attr_group,
382 bool cpu_is_hotpluggable(unsigned cpu)
384 struct device *dev = get_cpu_device(cpu);
385 return dev && container_of(dev, struct cpu, dev)->hotpluggable;
387 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
389 #ifdef CONFIG_GENERIC_CPU_DEVICES
390 static DEFINE_PER_CPU(struct cpu, cpu_devices);
393 static void __init cpu_dev_register_generic(void)
395 #ifdef CONFIG_GENERIC_CPU_DEVICES
398 for_each_possible_cpu(i) {
399 if (register_cpu(&per_cpu(cpu_devices, i), i))
400 panic("Failed to register CPU device");
405 void __init cpu_dev_init(void)
407 if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
408 panic("Failed to register CPU subsystem");
410 cpu_dev_register_generic();