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 #include <linux/node.h>
  12
  13 #include "base.h"
  14
  15 struct sysdev_class cpu_sysdev_class = {
  16         set_kset_name("cpu"),
  17 };
  18 EXPORT_SYMBOL(cpu_sysdev_class);
  19
  20 static struct sys_device *cpu_sys_devices[NR_CPUS];
  21
  22 #ifdef CONFIG_HOTPLUG_CPU
  23 static ssize_t show_online(struct sys_device *dev, char *buf)
  24 {
  25         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
  26
  27         return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id));
  28 }
  29
  30 static ssize_t store_online(struct sys_device *dev, const char *buf,
  31                             size_t count)
  32 {
  33         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
  34         ssize_t ret;
  35
  36         switch (buf[0]) {
  37         case '0':
  38                 ret = cpu_down(cpu->sysdev.id);
  39                 if (!ret)
  40                         kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
  41                 break;
  42         case '1':
  43                 ret = cpu_up(cpu->sysdev.id);
  44                 if (!ret)
  45                         kobject_uevent(&dev->kobj, KOBJ_ONLINE);
  46                 break;
  47         default:
  48                 ret = -EINVAL;
  49         }
  50
  51         if (ret >= 0)
  52                 ret = count;
  53         return ret;
  54 }
  55 static SYSDEV_ATTR(online, 0600, show_online, store_online);
  56
  57 static void __devinit register_cpu_control(struct cpu *cpu)
  58 {
  59         sysdev_create_file(&cpu->sysdev, &attr_online);
  60 }
  61 void unregister_cpu(struct cpu *cpu)
  62 {
  63         int logical_cpu = cpu->sysdev.id;
  64
  65         unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
  66
  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)
 113 {
 114         int error;
 115         cpu->node_id = cpu_to_node(num);
 116         cpu->sysdev.id = num;
 117         cpu->sysdev.cls = &cpu_sysdev_class;
 118
 119         error = sysdev_register(&cpu->sysdev);
 120
 121         if (!error && !cpu->no_control)
 122                 register_cpu_control(cpu);
 123         if (!error)
 124                 cpu_sys_devices[num] = &cpu->sysdev;
 125         if (!error)
 126                 register_cpu_under_node(num, cpu_to_node(num));
 127
 128 #ifdef CONFIG_KEXEC
 129         if (!error)
 130                 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
 131 #endif
 132         return error;
 133 }
 134
 135 struct sys_device *get_cpu_sysdev(unsigned cpu)
 136 {
 137         if (cpu < NR_CPUS)
 138                 return cpu_sys_devices[cpu];
 139         else
 140                 return NULL;
 141 }
 142 EXPORT_SYMBOL_GPL(get_cpu_sysdev);
 143
 144 int __init cpu_dev_init(void)
 145 {
 146         int err;
 147
 148         err = sysdev_class_register(&cpu_sysdev_class);
 149 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
 150         if (!err)
 151                 err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
 152 #endif
 153
 154         return err;
 155 }