bba70d08be6a6b072d3d07545e694d8983bf3aff
[linux-2.6.git] / drivers / base / cpu.c
1 /*
2  * CPU subsystem support
3  */
4
5 #include <linux/kernel.h>
6 #include <linux/module.h>
7 #include <linux/init.h>
8 #include <linux/sched.h>
9 #include <linux/cpu.h>
10 #include <linux/topology.h>
11 #include <linux/device.h>
12 #include <linux/node.h>
13 #include <linux/gfp.h>
14
15 #include "base.h"
16
17 struct bus_type cpu_subsys = {
18         .name = "cpu",
19         .dev_name = "cpu",
20 };
21 EXPORT_SYMBOL_GPL(cpu_subsys);
22
23 static DEFINE_PER_CPU(struct device *, cpu_sys_devices);
24
25 #ifdef CONFIG_HOTPLUG_CPU
26 static ssize_t show_online(struct device *dev,
27                            struct device_attribute *attr,
28                            char *buf)
29 {
30         struct cpu *cpu = container_of(dev, struct cpu, dev);
31
32         return sprintf(buf, "%u\n", !!cpu_online(cpu->dev.id));
33 }
34
35 static ssize_t __ref store_online(struct device *dev,
36                                   struct device_attribute *attr,
37                                   const char *buf, size_t count)
38 {
39         struct cpu *cpu = container_of(dev, struct cpu, dev);
40         ssize_t ret;
41
42         cpu_hotplug_driver_lock();
43         switch (buf[0]) {
44         case '0':
45                 ret = cpu_down(cpu->dev.id);
46                 if (!ret)
47                         kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
48                 break;
49         case '1':
50                 ret = cpu_up(cpu->dev.id);
51                 if (!ret)
52                         kobject_uevent(&dev->kobj, KOBJ_ONLINE);
53                 break;
54         default:
55                 ret = -EINVAL;
56         }
57         cpu_hotplug_driver_unlock();
58
59         if (ret >= 0)
60                 ret = count;
61         return ret;
62 }
63 static DEVICE_ATTR(online, 0644, show_online, store_online);
64
65 static void __cpuinit register_cpu_control(struct cpu *cpu)
66 {
67         device_create_file(&cpu->dev, &dev_attr_online);
68 }
69 void unregister_cpu(struct cpu *cpu)
70 {
71         int logical_cpu = cpu->dev.id;
72
73         unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
74
75         device_remove_file(&cpu->dev, &dev_attr_online);
76
77         device_unregister(&cpu->dev);
78         per_cpu(cpu_sys_devices, logical_cpu) = NULL;
79         return;
80 }
81
82 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
83 static ssize_t cpu_probe_store(struct device *dev,
84                                struct device_attribute *attr,
85                                const char *buf,
86                                size_t count)
87 {
88         return arch_cpu_probe(buf, count);
89 }
90
91 static ssize_t cpu_release_store(struct device *dev,
92                                  struct device_attribute *attr,
93                                  const char *buf,
94                                  size_t count)
95 {
96         return arch_cpu_release(buf, count);
97 }
98
99 static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
100 static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
101 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
102
103 #else /* ... !CONFIG_HOTPLUG_CPU */
104 static inline void register_cpu_control(struct cpu *cpu)
105 {
106 }
107 #endif /* CONFIG_HOTPLUG_CPU */
108
109 #ifdef CONFIG_KEXEC
110 #include <linux/kexec.h>
111
112 static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr,
113                                 char *buf)
114 {
115         struct cpu *cpu = container_of(dev, struct cpu, dev);
116         ssize_t rc;
117         unsigned long long addr;
118         int cpunum;
119
120         cpunum = cpu->dev.id;
121
122         /*
123          * Might be reading other cpu's data based on which cpu read thread
124          * has been scheduled. But cpu data (memory) is allocated once during
125          * boot up and this data does not change there after. Hence this
126          * operation should be safe. No locking required.
127          */
128         addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
129         rc = sprintf(buf, "%Lx\n", addr);
130         return rc;
131 }
132 static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL);
133 #endif
134
135 /*
136  * Print cpu online, possible, present, and system maps
137  */
138
139 struct cpu_attr {
140         struct device_attribute attr;
141         const struct cpumask *const * const map;
142 };
143
144 static ssize_t show_cpus_attr(struct device *dev,
145                               struct device_attribute *attr,
146                               char *buf)
147 {
148         struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
149         int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map));
150
151         buf[n++] = '\n';
152         buf[n] = '\0';
153         return n;
154 }
155
156 #define _CPU_ATTR(name, map) \
157         { __ATTR(name, 0444, show_cpus_attr, NULL), map }
158
159 /* Keep in sync with cpu_subsys_attrs */
160 static struct cpu_attr cpu_attrs[] = {
161         _CPU_ATTR(online, &cpu_online_mask),
162         _CPU_ATTR(possible, &cpu_possible_mask),
163         _CPU_ATTR(present, &cpu_present_mask),
164 };
165
166 /*
167  * Print values for NR_CPUS and offlined cpus
168  */
169 static ssize_t print_cpus_kernel_max(struct device *dev,
170                                      struct device_attribute *attr, char *buf)
171 {
172         int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
173         return n;
174 }
175 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
176
177 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
178 unsigned int total_cpus;
179
180 static ssize_t print_cpus_offline(struct device *dev,
181                                   struct device_attribute *attr, char *buf)
182 {
183         int n = 0, len = PAGE_SIZE-2;
184         cpumask_var_t offline;
185
186         /* display offline cpus < nr_cpu_ids */
187         if (!alloc_cpumask_var(&offline, GFP_KERNEL))
188                 return -ENOMEM;
189         cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
190         n = cpulist_scnprintf(buf, len, offline);
191         free_cpumask_var(offline);
192
193         /* display offline cpus >= nr_cpu_ids */
194         if (total_cpus && nr_cpu_ids < total_cpus) {
195                 if (n && n < len)
196                         buf[n++] = ',';
197
198                 if (nr_cpu_ids == total_cpus-1)
199                         n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
200                 else
201                         n += snprintf(&buf[n], len - n, "%d-%d",
202                                                       nr_cpu_ids, total_cpus-1);
203         }
204
205         n += snprintf(&buf[n], len - n, "\n");
206         return n;
207 }
208 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
209
210 /*
211  * register_cpu - Setup a sysfs device for a CPU.
212  * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
213  *        sysfs for this CPU.
214  * @num - CPU number to use when creating the device.
215  *
216  * Initialize and register the CPU device.
217  */
218 int __cpuinit register_cpu(struct cpu *cpu, int num)
219 {
220         int error;
221
222         cpu->node_id = cpu_to_node(num);
223         cpu->dev.id = num;
224         cpu->dev.bus = &cpu_subsys;
225         error = device_register(&cpu->dev);
226         if (!error && cpu->hotpluggable)
227                 register_cpu_control(cpu);
228         if (!error)
229                 per_cpu(cpu_sys_devices, num) = &cpu->dev;
230         if (!error)
231                 register_cpu_under_node(num, cpu_to_node(num));
232
233 #ifdef CONFIG_KEXEC
234         if (!error)
235                 error = device_create_file(&cpu->dev, &dev_attr_crash_notes);
236 #endif
237         return error;
238 }
239
240 struct device *get_cpu_device(unsigned cpu)
241 {
242         if (cpu < nr_cpu_ids && cpu_possible(cpu))
243                 return per_cpu(cpu_sys_devices, cpu);
244         else
245                 return NULL;
246 }
247 EXPORT_SYMBOL_GPL(get_cpu_device);
248
249 static struct attribute *cpu_root_attrs[] = {
250 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
251         &dev_attr_probe.attr,
252         &dev_attr_release.attr,
253 #endif
254         &cpu_attrs[0].attr.attr,
255         &cpu_attrs[1].attr.attr,
256         &cpu_attrs[2].attr.attr,
257         &dev_attr_kernel_max.attr,
258         &dev_attr_offline.attr,
259         NULL
260 };
261
262 static struct attribute_group cpu_root_attr_group = {
263         .attrs = cpu_root_attrs,
264 };
265
266 static const struct attribute_group *cpu_root_attr_groups[] = {
267         &cpu_root_attr_group,
268         NULL,
269 };
270
271 bool cpu_is_hotpluggable(unsigned cpu)
272 {
273         struct device *dev = get_cpu_device(cpu);
274         return dev && container_of(dev, struct cpu, dev)->hotpluggable;
275 }
276 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
277
278 void __init cpu_dev_init(void)
279 {
280         if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
281                 panic("Failed to register CPU subsystem");
282
283 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
284         sched_create_sysfs_power_savings_entries(cpu_subsys.dev_root);
285 #endif
286 }