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, char *buf)
  25 {
  26         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
  27
  28         return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id));
  29 }
  30
  31 static ssize_t __ref store_online(struct sys_device *dev, const char *buf,
  32                             size_t count)
  33 {
  34         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
  35         ssize_t ret;
  36
  37         switch (buf[0]) {
  38         case '0':
  39                 ret = cpu_down(cpu->sysdev.id);
  40                 if (!ret)
  41                         kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
  42                 break;
  43         case '1':
  44                 ret = cpu_up(cpu->sysdev.id);
  45                 if (!ret)
  46                         kobject_uevent(&dev->kobj, KOBJ_ONLINE);
  47                 break;
  48         default:
  49                 ret = -EINVAL;
  50         }
  51
  52         if (ret >= 0)
  53                 ret = count;
  54         return ret;
  55 }
  56 static SYSDEV_ATTR(online, 0644, show_online, store_online);
  57
  58 static void __cpuinit register_cpu_control(struct cpu *cpu)
  59 {
  60         sysdev_create_file(&cpu->sysdev, &attr_online);
  61 }
  62 void unregister_cpu(struct cpu *cpu)
  63 {
  64         int logical_cpu = cpu->sysdev.id;
  65
  66         unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
  67
  68         sysdev_remove_file(&cpu->sysdev, &attr_online);
  69
  70         sysdev_unregister(&cpu->sysdev);
  71         per_cpu(cpu_sys_devices, logical_cpu) = NULL;
  72         return;
  73 }
  74 #else /* ... !CONFIG_HOTPLUG_CPU */
  75 static inline void register_cpu_control(struct cpu *cpu)
  76 {
  77 }
  78 #endif /* CONFIG_HOTPLUG_CPU */
  79
  80 #ifdef CONFIG_KEXEC
  81 #include <linux/kexec.h>
  82
  83 static ssize_t show_crash_notes(struct sys_device *dev, char *buf)
  84 {
  85         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
  86         ssize_t rc;
  87         unsigned long long addr;
  88         int cpunum;
  89
  90         cpunum = cpu->sysdev.id;
  91
  92         /*
  93          * Might be reading other cpu's data based on which cpu read thread
  94          * has been scheduled. But cpu data (memory) is allocated once during
  95          * boot up and this data does not change there after. Hence this
  96          * operation should be safe. No locking required.
  97          */
  98         addr = __pa(per_cpu_ptr(crash_notes, cpunum));
  99         rc = sprintf(buf, "%Lx\n", addr);
 100         return rc;
 101 }
 102 static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
 103 #endif
 104
 105 /*
 106  * Print cpu online, possible, present, and system maps
 107  */
 108 static ssize_t print_cpus_map(char *buf, cpumask_t *map)
 109 {
 110         int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *map);
 111
 112         buf[n++] = '\n';
 113         buf[n] = '\0';
 114         return n;
 115 }
 116
 117 #define print_cpus_func(type) \
 118 static ssize_t print_cpus_##type(struct sysdev_class *class, char *buf) \
 119 {                                                                       \
 120         return print_cpus_map(buf, &cpu_##type##_map);                  \
 121 }                                                                       \
 122 struct sysdev_class_attribute attr_##type##_map =                       \
 123         _SYSDEV_CLASS_ATTR(type, 0444, print_cpus_##type, NULL)
 124
 125 print_cpus_func(online);
 126 print_cpus_func(possible);
 127 print_cpus_func(present);
 128
 129 struct sysdev_class_attribute *cpu_state_attr[] = {
 130         &attr_online_map,
 131         &attr_possible_map,
 132         &attr_present_map,
 133 };
 134
 135 static int cpu_states_init(void)
 136 {
 137         int i;
 138         int err = 0;
 139
 140         for (i = 0;  i < ARRAY_SIZE(cpu_state_attr); i++) {
 141                 int ret;
 142                 ret = sysdev_class_create_file(&cpu_sysdev_class,
 143                                                 cpu_state_attr[i]);
 144                 if (!err)
 145                         err = ret;
 146         }
 147         return err;
 148 }
 149
 150 /*
 151  * register_cpu - Setup a sysfs device for a CPU.
 152  * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
 153  *        sysfs for this CPU.
 154  * @num - CPU number to use when creating the device.
 155  *
 156  * Initialize and register the CPU device.
 157  */
 158 int __cpuinit register_cpu(struct cpu *cpu, int num)
 159 {
 160         int error;
 161         cpu->node_id = cpu_to_node(num);
 162         cpu->sysdev.id = num;
 163         cpu->sysdev.cls = &cpu_sysdev_class;
 164
 165         error = sysdev_register(&cpu->sysdev);
 166
 167         if (!error && cpu->hotpluggable)
 168                 register_cpu_control(cpu);
 169         if (!error)
 170                 per_cpu(cpu_sys_devices, num) = &cpu->sysdev;
 171         if (!error)
 172                 register_cpu_under_node(num, cpu_to_node(num));
 173
 174 #ifdef CONFIG_KEXEC
 175         if (!error)
 176                 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
 177 #endif
 178         return error;
 179 }
 180
 181 struct sys_device *get_cpu_sysdev(unsigned cpu)
 182 {
 183         if (cpu < nr_cpu_ids && cpu_possible(cpu))
 184                 return per_cpu(cpu_sys_devices, cpu);
 185         else
 186                 return NULL;
 187 }
 188 EXPORT_SYMBOL_GPL(get_cpu_sysdev);
 189
 190 int __init cpu_dev_init(void)
 191 {
 192         int err;
 193
 194         err = sysdev_class_register(&cpu_sysdev_class);
 195         if (!err)
 196                 err = cpu_states_init();
 197
 198 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
 199         if (!err)
 200                 err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
 201 #endif
 202
 203         return err;
 204 }