LXR linux/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
  16struct sysdev_class cpu_sysdev_class = {
  17        set_kset_name("cpu"),
  18};
  19EXPORT_SYMBOL(cpu_sysdev_class);
  20
  21static struct sys_device *cpu_sys_devices[NR_CPUS];
  22
  23#ifdef CONFIG_HOTPLUG_CPU
  24static 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
  31static ssize_t 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}
  56static SYSDEV_ATTR(online, 0644, show_online, store_online);
  57
  58static void __devinit register_cpu_control(struct cpu *cpu)
  59{
  60        sysdev_create_file(&cpu->sysdev, &attr_online);
  61}
  62void 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        cpu_sys_devices[logical_cpu] = NULL;
  72        return;
  73}
  74#else /* ... !CONFIG_HOTPLUG_CPU */
  75static 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
  83static 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}
 102static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
 103#endif
 104
 105/*
 106 * register_cpu - Setup a sysfs device for a CPU.
 107 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
 108 *        sysfs for this CPU.
 109 * @num - CPU number to use when creating the device.
 110 *
 111 * Initialize and register the CPU device.
 112 */
 113int __devinit register_cpu(struct cpu *cpu, int num)
 114{
 115        int error;
 116        cpu->node_id = cpu_to_node(num);
 117        cpu->sysdev.id = num;
 118        cpu->sysdev.cls = &cpu_sysdev_class;
 119
 120        error = sysdev_register(&cpu->sysdev);
 121
 122        if (!error && cpu->hotpluggable)
 123                register_cpu_control(cpu);
 124        if (!error)
 125                cpu_sys_devices[num] = &cpu->sysdev;
 126        if (!error)
 127                register_cpu_under_node(num, cpu_to_node(num));
 128
 129#ifdef CONFIG_KEXEC
 130        if (!error)
 131                error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
 132#endif
 133        return error;
 134}
 135
 136struct sys_device *get_cpu_sysdev(unsigned cpu)
 137{
 138        if (cpu < NR_CPUS)
 139                return cpu_sys_devices[cpu];
 140        else
 141                return NULL;
 142}
 143EXPORT_SYMBOL_GPL(get_cpu_sysdev);
 144
 145int __init cpu_dev_init(void)
 146{
 147        int err;
 148
 149        err = sysdev_class_register(&cpu_sysdev_class);
 150#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
 151        if (!err)
 152                err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
 153#endif
 154
 155        return err;
 156}
 157