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, struct sysdev_attribute *attr,
  25                            char *buf)
  26 {
  27         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
  28
  29         return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id));
  30 }
  31
  32 static ssize_t __ref store_online(struct sys_device *dev, struct sysdev_attribute *attr,
  33                                  const char *buf, size_t count)
  34 {
  35         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
  36         ssize_t ret;
  37
  38         switch (buf[0]) {
  39         case '0':
  40                 ret = cpu_down(cpu->sysdev.id);
  41                 if (!ret)
  42                         kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
  43                 break;
  44         case '1':
  45                 ret = cpu_up(cpu->sysdev.id);
  46                 if (!ret)
  47                         kobject_uevent(&dev->kobj, KOBJ_ONLINE);
  48                 break;
  49         default:
  50                 ret = -EINVAL;
  51         }
  52
  53         if (ret >= 0)
  54                 ret = count;
  55         return ret;
  56 }
  57 static SYSDEV_ATTR(online, 0644, show_online, store_online);
  58
  59 static void __cpuinit register_cpu_control(struct cpu *cpu)
  60 {
  61         sysdev_create_file(&cpu->sysdev, &attr_online);
  62 }
  63 void unregister_cpu(struct cpu *cpu)
  64 {
  65         int logical_cpu = cpu->sysdev.id;
  66
  67         unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
  68
  69         sysdev_remove_file(&cpu->sysdev, &attr_online);
  70
  71         sysdev_unregister(&cpu->sysdev);
  72         per_cpu(cpu_sys_devices, logical_cpu) = NULL;
  73         return;
  74 }
  75 #else /* ... !CONFIG_HOTPLUG_CPU */
  76 static inline void register_cpu_control(struct cpu *cpu)
  77 {
  78 }
  79 #endif /* CONFIG_HOTPLUG_CPU */
  80
  81 #ifdef CONFIG_KEXEC
  82 #include <linux/kexec.h>
  83
  84 static ssize_t show_crash_notes(struct sys_device *dev, struct sysdev_attribute *attr,
  85                                 char *buf)
  86 {
  87         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
  88         ssize_t rc;
  89         unsigned long long addr;
  90         int cpunum;
  91
  92         cpunum = cpu->sysdev.id;
  93
  94         /*
  95          * Might be reading other cpu's data based on which cpu read thread
  96          * has been scheduled. But cpu data (memory) is allocated once during
  97          * boot up and this data does not change there after. Hence this
  98          * operation should be safe. No locking required.
  99          */
 100         addr = __pa(per_cpu_ptr(crash_notes, cpunum));
 101         rc = sprintf(buf, "%Lx\n", addr);
 102         return rc;
 103 }
 104 static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
 105 #endif
 106
 107 /*
 108  * Print cpu online, possible, present, and system maps
 109  */
 110 static ssize_t print_cpus_map(char *buf, cpumask_t *map)
 111 {
 112         int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *map);
 113
 114         buf[n++] = '\n';
 115         buf[n] = '\0';
 116         return n;
 117 }
 118
 119 #define print_cpus_func(type) \
 120 static ssize_t print_cpus_##type(struct sysdev_class *class, char *buf) \
 121 {                                                                       \
 122         return print_cpus_map(buf, &cpu_##type##_map);                  \
 123 }                                                                       \
 124 static struct sysdev_class_attribute attr_##type##_map =                \
 125         _SYSDEV_CLASS_ATTR(type, 0444, print_cpus_##type, NULL)
 126
 127 print_cpus_func(online);
 128 print_cpus_func(possible);
 129 print_cpus_func(present);
 130
 131 static struct sysdev_class_attribute *cpu_state_attr[] = {
 132         &attr_online_map,
 133         &attr_possible_map,
 134         &attr_present_map,
 135 };
 136
 137 static int cpu_states_init(void)
 138 {
 139         int i;
 140         int err = 0;
 141
 142         for (i = 0;  i < ARRAY_SIZE(cpu_state_attr); i++) {
 143                 int ret;
 144                 ret = sysdev_class_create_file(&cpu_sysdev_class,
 145                                                 cpu_state_attr[i]);
 146                 if (!err)
 147                         err = ret;
 148         }
 149         return err;
 150 }
 151
 152 /*
 153  * register_cpu - Setup a sysfs device for a CPU.
 154  * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
 155  *        sysfs for this CPU.
 156  * @num - CPU number to use when creating the device.
 157  *
 158  * Initialize and register the CPU device.
 159  */
 160 int __cpuinit register_cpu(struct cpu *cpu, int num)
 161 {
 162         int error;
 163         cpu->node_id = cpu_to_node(num);
 164         cpu->sysdev.id = num;
 165         cpu->sysdev.cls = &cpu_sysdev_class;
 166
 167         error = sysdev_register(&cpu->sysdev);
 168
 169         if (!error && cpu->hotpluggable)
 170                 register_cpu_control(cpu);
 171         if (!error)
 172                 per_cpu(cpu_sys_devices, num) = &cpu->sysdev;
 173         if (!error)
 174                 register_cpu_under_node(num, cpu_to_node(num));
 175
 176 #ifdef CONFIG_KEXEC
 177         if (!error)
 178                 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
 179 #endif
 180         return error;
 181 }
 182
 183 struct sys_device *get_cpu_sysdev(unsigned cpu)
 184 {
 185         if (cpu < nr_cpu_ids && cpu_possible(cpu))
 186                 return per_cpu(cpu_sys_devices, cpu);
 187         else
 188                 return NULL;
 189 }
 190 EXPORT_SYMBOL_GPL(get_cpu_sysdev);
 191
 192 int __init cpu_dev_init(void)
 193 {
 194         int err;
 195
 196         err = sysdev_class_register(&cpu_sysdev_class);
 197         if (!err)
 198                 err = cpu_states_init();
 199
 200 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
 201         if (!err)
 202                 err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
 203 #endif
 204
 205         return err;
 206 }