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, const struct cpumask *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##_mask);                  \
 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 /*
 132  * Print values for NR_CPUS and offlined cpus
 133  */
 134 static ssize_t print_cpus_kernel_max(struct sysdev_class *class, char *buf)
 135 {
 136         int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
 137         return n;
 138 }
 139 static SYSDEV_CLASS_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
 140
 141 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
 142 unsigned int total_cpus;
 143
 144 static ssize_t print_cpus_offline(struct sysdev_class *class, char *buf)
 145 {
 146         int n = 0, len = PAGE_SIZE-2;
 147         cpumask_var_t offline;
 148
 149         /* display offline cpus < nr_cpu_ids */
 150         if (!alloc_cpumask_var(&offline, GFP_KERNEL))
 151                 return -ENOMEM;
 152         cpumask_complement(offline, cpu_online_mask);
 153         n = cpulist_scnprintf(buf, len, offline);
 154         free_cpumask_var(offline);
 155
 156         /* display offline cpus >= nr_cpu_ids */
 157         if (total_cpus && nr_cpu_ids < total_cpus) {
 158                 if (n && n < len)
 159                         buf[n++] = ',';
 160
 161                 if (nr_cpu_ids == total_cpus-1)
 162                         n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
 163                 else
 164                         n += snprintf(&buf[n], len - n, "%d-%d",
 165                                                       nr_cpu_ids, total_cpus-1);
 166         }
 167
 168         n += snprintf(&buf[n], len - n, "\n");
 169         return n;
 170 }
 171 static SYSDEV_CLASS_ATTR(offline, 0444, print_cpus_offline, NULL);
 172
 173 static struct sysdev_class_attribute *cpu_state_attr[] = {
 174         &attr_online_map,
 175         &attr_possible_map,
 176         &attr_present_map,
 177         &attr_kernel_max,
 178         &attr_offline,
 179 };
 180
 181 static int cpu_states_init(void)
 182 {
 183         int i;
 184         int err = 0;
 185
 186         for (i = 0;  i < ARRAY_SIZE(cpu_state_attr); i++) {
 187                 int ret;
 188                 ret = sysdev_class_create_file(&cpu_sysdev_class,
 189                                                 cpu_state_attr[i]);
 190                 if (!err)
 191                         err = ret;
 192         }
 193         return err;
 194 }
 195
 196 /*
 197  * register_cpu - Setup a sysfs device for a CPU.
 198  * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
 199  *        sysfs for this CPU.
 200  * @num - CPU number to use when creating the device.
 201  *
 202  * Initialize and register the CPU device.
 203  */
 204 int __cpuinit register_cpu(struct cpu *cpu, int num)
 205 {
 206         int error;
 207         cpu->node_id = cpu_to_node(num);
 208         cpu->sysdev.id = num;
 209         cpu->sysdev.cls = &cpu_sysdev_class;
 210
 211         error = sysdev_register(&cpu->sysdev);
 212
 213         if (!error && cpu->hotpluggable)
 214                 register_cpu_control(cpu);
 215         if (!error)
 216                 per_cpu(cpu_sys_devices, num) = &cpu->sysdev;
 217         if (!error)
 218                 register_cpu_under_node(num, cpu_to_node(num));
 219
 220 #ifdef CONFIG_KEXEC
 221         if (!error)
 222                 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
 223 #endif
 224         return error;
 225 }
 226
 227 struct sys_device *get_cpu_sysdev(unsigned cpu)
 228 {
 229         if (cpu < nr_cpu_ids && cpu_possible(cpu))
 230                 return per_cpu(cpu_sys_devices, cpu);
 231         else
 232                 return NULL;
 233 }
 234 EXPORT_SYMBOL_GPL(get_cpu_sysdev);
 235
 236 int __init cpu_dev_init(void)
 237 {
 238         int err;
 239
 240         err = sysdev_class_register(&cpu_sysdev_class);
 241         if (!err)
 242                 err = cpu_states_init();
 243
 244 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
 245         if (!err)
 246                 err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
 247 #endif
 248
 249         return err;
 250 }