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         set_kset_name("cpu"),
  18 };
  19 EXPORT_SYMBOL(cpu_sysdev_class);
  20
  21 static struct sys_device *cpu_sys_devices[NR_CPUS];
  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 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, 0600, show_online, store_online);
  57
  58 static void __devinit 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         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  * register_cpu - Setup a driverfs 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  */
 113 int __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
 136 struct 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 }
 143 EXPORT_SYMBOL_GPL(get_cpu_sysdev);
 144
 145 int __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 }