1 /*
2 * drivers/base/cpu.c - basic CPU class support
3 */
4
5 #include <linux/sysdev.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
14 #include "base.h"
15
16 struct sysdev_class cpu_sysdev_class = {
17 .name = "cpu",
18 };
19 EXPORT_SYMBOL(cpu_sysdev_class);
20
21 static DEFINE_PER_CPU(struct sys_device *, cpu_sys_devices);
22
23 #ifdef CONFIG_HOTPLUG_CPU
24 static ssize_t show_online(struct sys_device *dev, struct sysdev_attribute *attr,
25 char *buf)
26 {
27 struct cpu *cpu = container_of(dev, struct cpu, sysdev);
28
29 return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id));
30 }
31
32 static ssize_t __ref store_online(struct sys_device *dev, struct sysdev_attribute *attr,
33 const char *buf, size_t count)
34 {
35 struct cpu *cpu = container_of(dev, struct cpu, sysdev);
36 ssize_t ret;
37
38 switch (buf[0]) {
39 case '':
40 ret = cpu_down(cpu->sysdev.id);
41 if (!ret)
42 kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
43 break;
44 case '1':
45 ret = cpu_up(cpu->sysdev.id);
46 if (!ret)
47 kobject_uevent(&dev->kobj, KOBJ_ONLINE);
48 break;
49 default:
50 ret = -EINVAL;
51 }
52
53 if (ret >= 0)
54 ret = count;
55 return ret;
56 }
57 static SYSDEV_ATTR(online, 0644, show_online, store_online);
58
59 static void __cpuinit register_cpu_control(struct cpu *cpu)
60 {
61 sysdev_create_file(&cpu->sysdev, &attr_online);
62 }
63 void unregister_cpu(struct cpu *cpu)
64 {
65 int logical_cpu = cpu->sysdev.id;
66
67 unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
68
69 sysdev_remove_file(&cpu->sysdev, &attr_online);
70
71 sysdev_unregister(&cpu->sysdev);
72 per_cpu(cpu_sys_devices, logical_cpu) = NULL;
73 return;
74 }
75 #else /* ... !CONFIG_HOTPLUG_CPU */
76 static inline void register_cpu_control(struct cpu *cpu)
77 {
78 }
79 #endif /* CONFIG_HOTPLUG_CPU */
80
81 #ifdef CONFIG_KEXEC
82 #include <linux/kexec.h>
83
84 static ssize_t show_crash_notes(struct sys_device *dev, struct sysdev_attribute *attr,
85 char *buf)
86 {
87 struct cpu *cpu = container_of(dev, struct cpu, sysdev);
88 ssize_t rc;
89 unsigned long long addr;
90 int cpunum;
91
92 cpunum = cpu->sysdev.id;
93
94 /*
95 * Might be reading other cpu's data based on which cpu read thread
96 * has been scheduled. But cpu data (memory) is allocated once during
97 * boot up and this data does not change there after. Hence this
98 * operation should be safe. No locking required.
99 */
100 addr = __pa(per_cpu_ptr(crash_notes, cpunum));
101 rc = sprintf(buf, "%Lx\n", addr);
102 return rc;
103 }
104 static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
105 #endif
106
107 /*
108 * Print cpu online, possible, present, and system maps
109 */
110 static ssize_t print_cpus_map(char *buf, const struct cpumask *map)
111 {
112 int n = cpulist_scnprintf(buf, PAGE_SIZE-2, map);
113
114 buf[n++] = '\n';
115 buf[n] = '\0';
116 return n;
117 }
118
119 #define print_cpus_func(type) \
120 static ssize_t print_cpus_##type(struct sysdev_class *class, char *buf) \
121 { \
122 return print_cpus_map(buf, cpu_##type##_mask); \
123 } \
124 static struct sysdev_class_attribute attr_##type##_map = \
125 _SYSDEV_CLASS_ATTR(type, 0444, print_cpus_##type, NULL)
126
127 print_cpus_func(online);
128 print_cpus_func(possible);
129 print_cpus_func(present);
130
131 /*
132 * Print values for NR_CPUS and offlined cpus
133 */
134 static ssize_t print_cpus_kernel_max(struct sysdev_class *class, char *buf)
135 {
136 int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
137 return n;
138 }
139 static SYSDEV_CLASS_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
140
141 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
142 unsigned int total_cpus;
143
144 static ssize_t print_cpus_offline(struct sysdev_class *class, char *buf)
145 {
146 int n = 0, len = PAGE_SIZE-2;
147 cpumask_var_t offline;
148
149 /* display offline cpus < nr_cpu_ids */
150 if (!alloc_cpumask_var(&offline, GFP_KERNEL))
151 return -ENOMEM;
152 cpumask_complement(offline, cpu_online_mask);
153 n = cpulist_scnprintf(buf, len, offline);
154 free_cpumask_var(offline);
155
156 /* display offline cpus >= nr_cpu_ids */
157 if (total_cpus && nr_cpu_ids < total_cpus) {
158 if (n && n < len)
159 buf[n++] = ',';
160
161 if (nr_cpu_ids == total_cpus-1)
162 n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
163 else
164 n += snprintf(&buf[n], len - n, "%d-%d",
165 nr_cpu_ids, total_cpus-1);
166 }
167
168 n += snprintf(&buf[n], len - n, "\n");
169 return n;
170 }
171 static SYSDEV_CLASS_ATTR(offline, 0444, print_cpus_offline, NULL);
172
173 static struct sysdev_class_attribute *cpu_state_attr[] = {
174 &attr_online_map,
175 &attr_possible_map,
176 &attr_present_map,
177 &attr_kernel_max,
178 &attr_offline,
179 };
180
181 static int cpu_states_init(void)
182 {
183 int i;
184 int err = 0;
185
186 for (i = 0; i < ARRAY_SIZE(cpu_state_attr); i++) {
187 int ret;
188 ret = sysdev_class_create_file(&cpu_sysdev_class,
189 cpu_state_attr[i]);
190 if (!err)
191 err = ret;
192 }
193 return err;
194 }
195
196 /*
197 * register_cpu - Setup a sysfs device for a CPU.
198 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
199 * sysfs for this CPU.
200 * @num - CPU number to use when creating the device.
201 *
202 * Initialize and register the CPU device.
203 */
204 int __cpuinit register_cpu(struct cpu *cpu, int num)
205 {
206 int error;
207 cpu->node_id = cpu_to_node(num);
208 cpu->sysdev.id = num;
209 cpu->sysdev.cls = &cpu_sysdev_class;
210
211 error = sysdev_register(&cpu->sysdev);
212
213 if (!error && cpu->hotpluggable)
214 register_cpu_control(cpu);
215 if (!error)
216 per_cpu(cpu_sys_devices, num) = &cpu->sysdev;
217 if (!error)
218 register_cpu_under_node(num, cpu_to_node(num));
219
220 #ifdef CONFIG_KEXEC
221 if (!error)
222 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
223 #endif
224 return error;
225 }
226
227 struct sys_device *get_cpu_sysdev(unsigned cpu)
228 {
229 if (cpu < nr_cpu_ids && cpu_possible(cpu))
230 return per_cpu(cpu_sys_devices, cpu);
231 else
232 return NULL;
233 }
234 EXPORT_SYMBOL_GPL(get_cpu_sysdev);
235
236 int __init cpu_dev_init(void)
237 {
238 int err;
239
240 err = sysdev_class_register(&cpu_sysdev_class);
241 if (!err)
242 err = cpu_states_init();
243
244 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
245 if (!err)
246 err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
247 #endif
248
249 return err;
250 }
251
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