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/cpu.h>
   9 #include <linux/topology.h>
  10 #include <linux/device.h>
  11
  12 #include "base.h"
  13
  14 struct sysdev_class cpu_sysdev_class = {
  15         set_kset_name("cpu"),
  16 };
  17 EXPORT_SYMBOL(cpu_sysdev_class);
  18
  19 static struct sys_device *cpu_sys_devices[NR_CPUS];
  20
  21 #ifdef CONFIG_HOTPLUG_CPU
  22 static ssize_t show_online(struct sys_device *dev, char *buf)
  23 {
  24         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
  25
  26         return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id));
  27 }
  28
  29 static ssize_t store_online(struct sys_device *dev, const char *buf,
  30                             size_t count)
  31 {
  32         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
  33         ssize_t ret;
  34
  35         switch (buf[0]) {
  36         case '0':
  37                 ret = cpu_down(cpu->sysdev.id);
  38                 if (!ret)
  39                         kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
  40                 break;
  41         case '1':
  42                 ret = cpu_up(cpu->sysdev.id);
  43                 if (!ret)
  44                         kobject_uevent(&dev->kobj, KOBJ_ONLINE);
  45                 break;
  46         default:
  47                 ret = -EINVAL;
  48         }
  49
  50         if (ret >= 0)
  51                 ret = count;
  52         return ret;
  53 }
  54 static SYSDEV_ATTR(online, 0600, show_online, store_online);
  55
  56 static void __devinit register_cpu_control(struct cpu *cpu)
  57 {
  58         sysdev_create_file(&cpu->sysdev, &attr_online);
  59 }
  60 void unregister_cpu(struct cpu *cpu, struct node *root)
  61 {
  62         int logical_cpu = cpu->sysdev.id;
  63
  64         if (root)
  65                 sysfs_remove_link(&root->sysdev.kobj,
  66                                   kobject_name(&cpu->sysdev.kobj));
  67         sysdev_remove_file(&cpu->sysdev, &attr_online);
  68
  69         sysdev_unregister(&cpu->sysdev);
  70         cpu_sys_devices[logical_cpu] = NULL;
  71         return;
  72 }
  73 #else /* ... !CONFIG_HOTPLUG_CPU */
  74 static inline void register_cpu_control(struct cpu *cpu)
  75 {
  76 }
  77 #endif /* CONFIG_HOTPLUG_CPU */
  78
  79 #ifdef CONFIG_KEXEC
  80 #include <linux/kexec.h>
  81
  82 static ssize_t show_crash_notes(struct sys_device *dev, char *buf)
  83 {
  84         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
  85         ssize_t rc;
  86         unsigned long long addr;
  87         int cpunum;
  88
  89         cpunum = cpu->sysdev.id;
  90
  91         /*
  92          * Might be reading other cpu's data based on which cpu read thread
  93          * has been scheduled. But cpu data (memory) is allocated once during
  94          * boot up and this data does not change there after. Hence this
  95          * operation should be safe. No locking required.
  96          */
  97         addr = __pa(per_cpu_ptr(crash_notes, cpunum));
  98         rc = sprintf(buf, "%Lx\n", addr);
  99         return rc;
 100 }
 101 static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
 102 #endif
 103
 104 /*
 105  * register_cpu - Setup a driverfs device for a CPU.
 106  * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to
 107  *                generate a control file in sysfs for this CPU.
 108  * @num - CPU number to use when creating the device.
 109  *
 110  * Initialize and register the CPU device.
 111  */
 112 int __devinit register_cpu(struct cpu *cpu, int num, struct node *root)
 113 {
 114         int error;
 115
 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         if (!error && root)
 122                 error = sysfs_create_link(&root->sysdev.kobj,
 123                                           &cpu->sysdev.kobj,
 124                                           kobject_name(&cpu->sysdev.kobj));
 125         if (!error && !cpu->no_control)
 126                 register_cpu_control(cpu);
 127         if (!error)
 128                 cpu_sys_devices[num] = &cpu->sysdev;
 129
 130 #ifdef CONFIG_KEXEC
 131         if (!error)
 132                 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
 133 #endif
 134         return error;
 135 }
 136
 137 struct sys_device *get_cpu_sysdev(unsigned cpu)
 138 {
 139         if (cpu < NR_CPUS)
 140                 return cpu_sys_devices[cpu];
 141         else
 142                 return NULL;
 143 }
 144 EXPORT_SYMBOL_GPL(get_cpu_sysdev);
 145
 146 int __init cpu_dev_init(void)
 147 {
 148         return sysdev_class_register(&cpu_sysdev_class);
 149 }