drivers/base/cpu.c

   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 '0':
  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
  76 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
  77 static ssize_t cpu_probe_store(struct class *class, const char *buf,
  78                                size_t count)
  79 {
  80         return arch_cpu_probe(buf, count);
  81 }
  82
  83 static ssize_t cpu_release_store(struct class *class, const char *buf,
  84                                  size_t count)
  85 {
  86         return arch_cpu_release(buf, count);
  87 }
  88
  89 static CLASS_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
  90 static CLASS_ATTR(release, S_IWUSR, NULL, cpu_release_store);
  91
  92 int __init cpu_probe_release_init(void)
  93 {
  94         int rc;
  95
  96         rc = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
  97                                &class_attr_probe.attr);
  98         if (!rc)
  99                 rc = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
 100                                        &class_attr_release.attr);
 101
 102         return rc;
 103 }
 104 device_initcall(cpu_probe_release_init);
 105 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
 106
 107 #else /* ... !CONFIG_HOTPLUG_CPU */
 108 static inline void register_cpu_control(struct cpu *cpu)
 109 {
 110 }
 111 #endif /* CONFIG_HOTPLUG_CPU */
 112
 113 #ifdef CONFIG_KEXEC
 114 #include <linux/kexec.h>
 115
 116 static ssize_t show_crash_notes(struct sys_device *dev, struct sysdev_attribute *attr,
 117                                 char *buf)
 118 {
 119         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
 120         ssize_t rc;
 121         unsigned long long addr;
 122         int cpunum;
 123
 124         cpunum = cpu->sysdev.id;
 125
 126         /*
 127          * Might be reading other cpu's data based on which cpu read thread
 128          * has been scheduled. But cpu data (memory) is allocated once during
 129          * boot up and this data does not change there after. Hence this
 130          * operation should be safe. No locking required.
 131          */
 132         addr = __pa(per_cpu_ptr(crash_notes, cpunum));
 133         rc = sprintf(buf, "%Lx\n", addr);
 134         return rc;
 135 }
 136 static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
 137 #endif
 138
 139 /*
 140  * Print cpu online, possible, present, and system maps
 141  */
 142 static ssize_t print_cpus_map(char *buf, const struct cpumask *map)
 143 {
 144         int n = cpulist_scnprintf(buf, PAGE_SIZE-2, map);
 145
 146         buf[n++] = '\n';
 147         buf[n] = '\0';
 148         return n;
 149 }
 150
 151 #define print_cpus_func(type) \
 152 static ssize_t print_cpus_##type(struct sysdev_class *class, char *buf) \
 153 {                                                                       \
 154         return print_cpus_map(buf, cpu_##type##_mask);                  \
 155 }                                                                       \
 156 static struct sysdev_class_attribute attr_##type##_map =                \
 157         _SYSDEV_CLASS_ATTR(type, 0444, print_cpus_##type, NULL)
 158
 159 print_cpus_func(online);
 160 print_cpus_func(possible);
 161 print_cpus_func(present);
 162
 163 /*
 164  * Print values for NR_CPUS and offlined cpus
 165  */
 166 static ssize_t print_cpus_kernel_max(struct sysdev_class *class, char *buf)
 167 {
 168         int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
 169         return n;
 170 }
 171 static SYSDEV_CLASS_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
 172
 173 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
 174 unsigned int total_cpus;
 175
 176 static ssize_t print_cpus_offline(struct sysdev_class *class, char *buf)
 177 {
 178         int n = 0, len = PAGE_SIZE-2;
 179         cpumask_var_t offline;
 180
 181         /* display offline cpus < nr_cpu_ids */
 182         if (!alloc_cpumask_var(&offline, GFP_KERNEL))
 183                 return -ENOMEM;
 184         cpumask_complement(offline, cpu_online_mask);
 185         n = cpulist_scnprintf(buf, len, offline);
 186         free_cpumask_var(offline);
 187
 188         /* display offline cpus >= nr_cpu_ids */
 189         if (total_cpus && nr_cpu_ids < total_cpus) {
 190                 if (n && n < len)
 191                         buf[n++] = ',';
 192
 193                 if (nr_cpu_ids == total_cpus-1)
 194                         n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
 195                 else
 196                         n += snprintf(&buf[n], len - n, "%d-%d",
 197                                                       nr_cpu_ids, total_cpus-1);
 198         }
 199
 200         n += snprintf(&buf[n], len - n, "\n");
 201         return n;
 202 }
 203 static SYSDEV_CLASS_ATTR(offline, 0444, print_cpus_offline, NULL);
 204
 205 static struct sysdev_class_attribute *cpu_state_attr[] = {
 206         &attr_online_map,
 207         &attr_possible_map,
 208         &attr_present_map,
 209         &attr_kernel_max,
 210         &attr_offline,
 211 };
 212
 213 static int cpu_states_init(void)
 214 {
 215         int i;
 216         int err = 0;
 217
 218         for (i = 0;  i < ARRAY_SIZE(cpu_state_attr); i++) {
 219                 int ret;
 220                 ret = sysdev_class_create_file(&cpu_sysdev_class,
 221                                                 cpu_state_attr[i]);
 222                 if (!err)
 223                         err = ret;
 224         }
 225         return err;
 226 }
 227
 228 /*
 229  * register_cpu - Setup a sysfs device for a CPU.
 230  * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
 231  *        sysfs for this CPU.
 232  * @num - CPU number to use when creating the device.
 233  *
 234  * Initialize and register the CPU device.
 235  */
 236 int __cpuinit register_cpu(struct cpu *cpu, int num)
 237 {
 238         int error;
 239         cpu->node_id = cpu_to_node(num);
 240         cpu->sysdev.id = num;
 241         cpu->sysdev.cls = &cpu_sysdev_class;
 242
 243         error = sysdev_register(&cpu->sysdev);
 244
 245         if (!error && cpu->hotpluggable)
 246                 register_cpu_control(cpu);
 247         if (!error)
 248                 per_cpu(cpu_sys_devices, num) = &cpu->sysdev;
 249         if (!error)
 250                 register_cpu_under_node(num, cpu_to_node(num));
 251
 252 #ifdef CONFIG_KEXEC
 253         if (!error)
 254                 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
 255 #endif
 256         return error;
 257 }
 258
 259 struct sys_device *get_cpu_sysdev(unsigned cpu)
 260 {
 261         if (cpu < nr_cpu_ids && cpu_possible(cpu))
 262                 return per_cpu(cpu_sys_devices, cpu);
 263         else
 264                 return NULL;
 265 }
 266 EXPORT_SYMBOL_GPL(get_cpu_sysdev);
 267
 268 int __init cpu_dev_init(void)
 269 {
 270         int err;
 271
 272         err = sysdev_class_register(&cpu_sysdev_class);
 273         if (!err)
 274                 err = cpu_states_init();
 275
 276 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
 277         if (!err)
 278                 err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
 279 #endif
 280
 281         return err;
 282 }