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[~shefty/rdma-dev.git] / drivers / base / cpu.c
1 /*
2  * CPU subsystem support
3  */
4
5 #include <linux/module.h>
6 #include <linux/init.h>
7 #include <linux/sched.h>
8 #include <linux/cpu.h>
9 #include <linux/topology.h>
10 #include <linux/device.h>
11 #include <linux/node.h>
12 #include <linux/gfp.h>
13
14 #include "base.h"
15
16 struct bus_type cpu_subsys = {
17         .name = "cpu",
18         .dev_name = "cpu",
19 };
20 EXPORT_SYMBOL_GPL(cpu_subsys);
21
22 static DEFINE_PER_CPU(struct device *, cpu_sys_devices);
23
24 #ifdef CONFIG_HOTPLUG_CPU
25 static ssize_t show_online(struct device *dev,
26                            struct device_attribute *attr,
27                            char *buf)
28 {
29         struct cpu *cpu = container_of(dev, struct cpu, dev);
30
31         return sprintf(buf, "%u\n", !!cpu_online(cpu->dev.id));
32 }
33
34 static ssize_t __ref store_online(struct device *dev,
35                                   struct device_attribute *attr,
36                                   const char *buf, size_t count)
37 {
38         struct cpu *cpu = container_of(dev, struct cpu, dev);
39         ssize_t ret;
40
41         cpu_hotplug_driver_lock();
42         switch (buf[0]) {
43         case '0':
44                 ret = cpu_down(cpu->dev.id);
45                 if (!ret)
46                         kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
47                 break;
48         case '1':
49                 ret = cpu_up(cpu->dev.id);
50                 if (!ret)
51                         kobject_uevent(&dev->kobj, KOBJ_ONLINE);
52                 break;
53         default:
54                 ret = -EINVAL;
55         }
56         cpu_hotplug_driver_unlock();
57
58         if (ret >= 0)
59                 ret = count;
60         return ret;
61 }
62 static DEVICE_ATTR(online, 0644, show_online, store_online);
63
64 static void __cpuinit register_cpu_control(struct cpu *cpu)
65 {
66         device_create_file(&cpu->dev, &dev_attr_online);
67 }
68 void unregister_cpu(struct cpu *cpu)
69 {
70         int logical_cpu = cpu->dev.id;
71
72         unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
73
74         device_remove_file(&cpu->dev, &dev_attr_online);
75
76         device_unregister(&cpu->dev);
77         per_cpu(cpu_sys_devices, logical_cpu) = NULL;
78         return;
79 }
80
81 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
82 static ssize_t cpu_probe_store(struct device *dev,
83                                struct device_attribute *attr,
84                                const char *buf,
85                                size_t count)
86 {
87         return arch_cpu_probe(buf, count);
88 }
89
90 static ssize_t cpu_release_store(struct device *dev,
91                                  struct device_attribute *attr,
92                                  const char *buf,
93                                  size_t count)
94 {
95         return arch_cpu_release(buf, count);
96 }
97
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 */
101
102 #else /* ... !CONFIG_HOTPLUG_CPU */
103 static inline void register_cpu_control(struct cpu *cpu)
104 {
105 }
106 #endif /* CONFIG_HOTPLUG_CPU */
107
108 #ifdef CONFIG_KEXEC
109 #include <linux/kexec.h>
110
111 static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr,
112                                 char *buf)
113 {
114         struct cpu *cpu = container_of(dev, struct cpu, dev);
115         ssize_t rc;
116         unsigned long long addr;
117         int cpunum;
118
119         cpunum = cpu->dev.id;
120
121         /*
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.
126          */
127         addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
128         rc = sprintf(buf, "%Lx\n", addr);
129         return rc;
130 }
131 static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL);
132 #endif
133
134 /*
135  * Print cpu online, possible, present, and system maps
136  */
137
138 struct cpu_attr {
139         struct device_attribute attr;
140         const struct cpumask *const * const map;
141 };
142
143 static ssize_t show_cpus_attr(struct device *dev,
144                               struct device_attribute *attr,
145                               char *buf)
146 {
147         struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
148         int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map));
149
150         buf[n++] = '\n';
151         buf[n] = '\0';
152         return n;
153 }
154
155 #define _CPU_ATTR(name, map) \
156         { __ATTR(name, 0444, show_cpus_attr, NULL), map }
157
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),
163 };
164
165 /*
166  * Print values for NR_CPUS and offlined cpus
167  */
168 static ssize_t print_cpus_kernel_max(struct device *dev,
169                                      struct device_attribute *attr, char *buf)
170 {
171         int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
172         return n;
173 }
174 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
175
176 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
177 unsigned int total_cpus;
178
179 static ssize_t print_cpus_offline(struct device *dev,
180                                   struct device_attribute *attr, char *buf)
181 {
182         int n = 0, len = PAGE_SIZE-2;
183         cpumask_var_t offline;
184
185         /* display offline cpus < nr_cpu_ids */
186         if (!alloc_cpumask_var(&offline, GFP_KERNEL))
187                 return -ENOMEM;
188         cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
189         n = cpulist_scnprintf(buf, len, offline);
190         free_cpumask_var(offline);
191
192         /* display offline cpus >= nr_cpu_ids */
193         if (total_cpus && nr_cpu_ids < total_cpus) {
194                 if (n && n < len)
195                         buf[n++] = ',';
196
197                 if (nr_cpu_ids == total_cpus-1)
198                         n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
199                 else
200                         n += snprintf(&buf[n], len - n, "%d-%d",
201                                                       nr_cpu_ids, total_cpus-1);
202         }
203
204         n += snprintf(&buf[n], len - n, "\n");
205         return n;
206 }
207 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
208
209 /*
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.
214  *
215  * Initialize and register the CPU device.
216  */
217 int __cpuinit register_cpu(struct cpu *cpu, int num)
218 {
219         int error;
220
221         cpu->node_id = cpu_to_node(num);
222         cpu->dev.id = num;
223         cpu->dev.bus = &cpu_subsys;
224         error = device_register(&cpu->dev);
225         if (!error && cpu->hotpluggable)
226                 register_cpu_control(cpu);
227         if (!error)
228                 per_cpu(cpu_sys_devices, num) = &cpu->dev;
229         if (!error)
230                 register_cpu_under_node(num, cpu_to_node(num));
231
232 #ifdef CONFIG_KEXEC
233         if (!error)
234                 error = device_create_file(&cpu->dev, &dev_attr_crash_notes);
235 #endif
236         return error;
237 }
238
239 struct device *get_cpu_device(unsigned cpu)
240 {
241         if (cpu < nr_cpu_ids && cpu_possible(cpu))
242                 return per_cpu(cpu_sys_devices, cpu);
243         else
244                 return NULL;
245 }
246 EXPORT_SYMBOL_GPL(get_cpu_device);
247
248 static struct attribute *cpu_root_attrs[] = {
249 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
250         &dev_attr_probe.attr,
251         &dev_attr_release.attr,
252 #endif
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,
258         NULL
259 };
260
261 static struct attribute_group cpu_root_attr_group = {
262         .attrs = cpu_root_attrs,
263 };
264
265 static const struct attribute_group *cpu_root_attr_groups[] = {
266         &cpu_root_attr_group,
267         NULL,
268 };
269
270 bool cpu_is_hotpluggable(unsigned cpu)
271 {
272         struct device *dev = get_cpu_device(cpu);
273         return dev && container_of(dev, struct cpu, dev)->hotpluggable;
274 }
275 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
276
277 int __init cpu_dev_init(void)
278 {
279         int err;
280
281         err = subsys_system_register(&cpu_subsys, cpu_root_attr_groups);
282         if (err)
283                 return err;
284
285 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
286         err = sched_create_sysfs_power_savings_entries(cpu_subsys.dev_root);
287 #endif
288         return err;
289 }