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         cpu_hotplug_driver_lock();
  39         switch (buf[0]) {
  40         case '0':
  41                 ret = cpu_down(cpu->sysdev.id);
  42                 if (!ret)
  43                         kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
  44                 break;
  45         case '1':
  46                 ret = cpu_up(cpu->sysdev.id);
  47                 if (!ret)
  48                         kobject_uevent(&dev->kobj, KOBJ_ONLINE);
  49                 break;
  50         default:
  51                 ret = -EINVAL;
  52         }
  53         cpu_hotplug_driver_unlock();
  54
  55         if (ret >= 0)
  56                 ret = count;
  57         return ret;
  58 }
  59 static SYSDEV_ATTR(online, 0644, show_online, store_online);
  60
  61 static void __cpuinit register_cpu_control(struct cpu *cpu)
  62 {
  63         sysdev_create_file(&cpu->sysdev, &attr_online);
  64 }
  65 void unregister_cpu(struct cpu *cpu)
  66 {
  67         int logical_cpu = cpu->sysdev.id;
  68
  69         unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
  70
  71         sysdev_remove_file(&cpu->sysdev, &attr_online);
  72
  73         sysdev_unregister(&cpu->sysdev);
  74         per_cpu(cpu_sys_devices, logical_cpu) = NULL;
  75         return;
  76 }
  77
  78 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
  79 static ssize_t cpu_probe_store(struct class *class, const char *buf,
  80                                size_t count)
  81 {
  82         return arch_cpu_probe(buf, count);
  83 }
  84
  85 static ssize_t cpu_release_store(struct class *class, const char *buf,
  86                                  size_t count)
  87 {
  88         return arch_cpu_release(buf, count);
  89 }
  90
  91 static CLASS_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
  92 static CLASS_ATTR(release, S_IWUSR, NULL, cpu_release_store);
  93
  94 int __init cpu_probe_release_init(void)
  95 {
  96         int rc;
  97
  98         rc = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
  99                                &class_attr_probe.attr);
 100         if (!rc)
 101                 rc = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
 102                                        &class_attr_release.attr);
 103
 104         return rc;
 105 }
 106 device_initcall(cpu_probe_release_init);
 107 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
 108
 109 #else /* ... !CONFIG_HOTPLUG_CPU */
 110 static inline void register_cpu_control(struct cpu *cpu)
 111 {
 112 }
 113 #endif /* CONFIG_HOTPLUG_CPU */
 114
 115 #ifdef CONFIG_KEXEC
 116 #include <linux/kexec.h>
 117
 118 static ssize_t show_crash_notes(struct sys_device *dev, struct sysdev_attribute *attr,
 119                                 char *buf)
 120 {
 121         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
 122         ssize_t rc;
 123         unsigned long long addr;
 124         int cpunum;
 125
 126         cpunum = cpu->sysdev.id;
 127
 128         /*
 129          * Might be reading other cpu's data based on which cpu read thread
 130          * has been scheduled. But cpu data (memory) is allocated once during
 131          * boot up and this data does not change there after. Hence this
 132          * operation should be safe. No locking required.
 133          */
 134         addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
 135         rc = sprintf(buf, "%Lx\n", addr);
 136         return rc;
 137 }
 138 static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
 139 #endif
 140
 141 /*
 142  * Print cpu online, possible, present, and system maps
 143  */
 144 static ssize_t print_cpus_map(char *buf, const struct cpumask *map)
 145 {
 146         int n = cpulist_scnprintf(buf, PAGE_SIZE-2, map);
 147
 148         buf[n++] = '\n';
 149         buf[n] = '\0';
 150         return n;
 151 }
 152
 153 #define print_cpus_func(type) \
 154 static ssize_t print_cpus_##type(struct sysdev_class *class, char *buf) \
 155 {                                                                       \
 156         return print_cpus_map(buf, cpu_##type##_mask);                  \
 157 }                                                                       \
 158 static struct sysdev_class_attribute attr_##type##_map =                \
 159         _SYSDEV_CLASS_ATTR(type, 0444, print_cpus_##type, NULL)
 160
 161 print_cpus_func(online);
 162 print_cpus_func(possible);
 163 print_cpus_func(present);
 164
 165 /*
 166  * Print values for NR_CPUS and offlined cpus
 167  */
 168 static ssize_t print_cpus_kernel_max(struct sysdev_class *class, char *buf)
 169 {
 170         int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
 171         return n;
 172 }
 173 static SYSDEV_CLASS_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
 174
 175 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
 176 unsigned int total_cpus;
 177
 178 static ssize_t print_cpus_offline(struct sysdev_class *class, char *buf)
 179 {
 180         int n = 0, len = PAGE_SIZE-2;
 181         cpumask_var_t offline;
 182
 183         /* display offline cpus < nr_cpu_ids */
 184         if (!alloc_cpumask_var(&offline, GFP_KERNEL))
 185                 return -ENOMEM;
 186         cpumask_complement(offline, cpu_online_mask);
 187         n = cpulist_scnprintf(buf, len, offline);
 188         free_cpumask_var(offline);
 189
 190         /* display offline cpus >= nr_cpu_ids */
 191         if (total_cpus && nr_cpu_ids < total_cpus) {
 192                 if (n && n < len)
 193                         buf[n++] = ',';
 194
 195                 if (nr_cpu_ids == total_cpus-1)
 196                         n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
 197                 else
 198                         n += snprintf(&buf[n], len - n, "%d-%d",
 199                                                       nr_cpu_ids, total_cpus-1);
 200         }
 201
 202         n += snprintf(&buf[n], len - n, "\n");
 203         return n;
 204 }
 205 static SYSDEV_CLASS_ATTR(offline, 0444, print_cpus_offline, NULL);
 206
 207 static struct sysdev_class_attribute *cpu_state_attr[] = {
 208         &attr_online_map,
 209         &attr_possible_map,
 210         &attr_present_map,
 211         &attr_kernel_max,
 212         &attr_offline,
 213 };
 214
 215 static int cpu_states_init(void)
 216 {
 217         int i;
 218         int err = 0;
 219
 220         for (i = 0;  i < ARRAY_SIZE(cpu_state_attr); i++) {
 221                 int ret;
 222                 ret = sysdev_class_create_file(&cpu_sysdev_class,
 223                                                 cpu_state_attr[i]);
 224                 if (!err)
 225                         err = ret;
 226         }
 227         return err;
 228 }
 229
 230 /*
 231  * register_cpu - Setup a sysfs device for a CPU.
 232  * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
 233  *        sysfs for this CPU.
 234  * @num - CPU number to use when creating the device.
 235  *
 236  * Initialize and register the CPU device.
 237  */
 238 int __cpuinit register_cpu(struct cpu *cpu, int num)
 239 {
 240         int error;
 241         cpu->node_id = cpu_to_node(num);
 242         cpu->sysdev.id = num;
 243         cpu->sysdev.cls = &cpu_sysdev_class;
 244
 245         error = sysdev_register(&cpu->sysdev);
 246
 247         if (!error && cpu->hotpluggable)
 248                 register_cpu_control(cpu);
 249         if (!error)
 250                 per_cpu(cpu_sys_devices, num) = &cpu->sysdev;
 251         if (!error)
 252                 register_cpu_under_node(num, cpu_to_node(num));
 253
 254 #ifdef CONFIG_KEXEC
 255         if (!error)
 256                 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
 257 #endif
 258         return error;
 259 }
 260
 261 struct sys_device *get_cpu_sysdev(unsigned cpu)
 262 {
 263         if (cpu < nr_cpu_ids && cpu_possible(cpu))
 264                 return per_cpu(cpu_sys_devices, cpu);
 265         else
 266                 return NULL;
 267 }
 268 EXPORT_SYMBOL_GPL(get_cpu_sysdev);
 269
 270 int __init cpu_dev_init(void)
 271 {
 272         int err;
 273
 274         err = sysdev_class_register(&cpu_sysdev_class);
 275         if (!err)
 276                 err = cpu_states_init();
 277
 278 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
 279         if (!err)
 280                 err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
 281 #endif
 282
 283         return err;
 284 }