text: /*
   * sysfs.c - sysfs support
   *
   * (C) 2006-2007 Shaohua Li <shaohua.li@intel.com>
   *
   * This code is licenced under the GPL.
   */
  
  #include <linux/kernel.h>
  #include <linux/cpuidle.h>
  #include <linux/sysfs.h>
  #include <linux/slab.h>
  #include <linux/cpu.h>
  #include <linux/completion.h>
  #include <linux/capability.h>
  #include <linux/device.h>
  #include <linux/kobject.h>
  
  #include "cpuidle.h"
  
  static unsigned int sysfs_switch;
  static int __init cpuidle_sysfs_setup(char *unused)
  {
  	sysfs_switch = 1;
  	return 1;
  }
  __setup("cpuidle_sysfs_switch", cpuidle_sysfs_setup);
  
  static ssize_t show_available_governors(struct device *dev,
  					struct device_attribute *attr,
  					char *buf)
  {
  	ssize_t i = 0;
  	struct cpuidle_governor *tmp;
  
  	mutex_lock(&cpuidle_lock);
  	list_for_each_entry(tmp, &cpuidle_governors, governor_list) {
  		if (i >= (ssize_t) ((PAGE_SIZE/sizeof(char)) -
  				    CPUIDLE_NAME_LEN - 2))
  			goto out;
  		i += scnprintf(&buf[i], CPUIDLE_NAME_LEN, "%s ", tmp->name);
  	}
  
  out:
  	i+= sprintf(&buf[i], "\n");
  	mutex_unlock(&cpuidle_lock);
  	return i;
  }
  
  static ssize_t show_current_driver(struct device *dev,
  				   struct device_attribute *attr,
  				   char *buf)
  {
  	ssize_t ret;
  	struct cpuidle_driver *drv;
  
  	spin_lock(&cpuidle_driver_lock);
  	drv = cpuidle_get_driver();
  	if (drv)
  		ret = sprintf(buf, "%s\n", drv->name);
  	else
  		ret = sprintf(buf, "none\n");
  	spin_unlock(&cpuidle_driver_lock);
  
  	return ret;
  }
  
  static ssize_t show_current_governor(struct device *dev,
  				     struct device_attribute *attr,
  				     char *buf)
  {
  	ssize_t ret;
  
  	mutex_lock(&cpuidle_lock);
  	if (cpuidle_curr_governor)
  		ret = sprintf(buf, "%s\n", cpuidle_curr_governor->name);
  	else
  		ret = sprintf(buf, "none\n");
  	mutex_unlock(&cpuidle_lock);
  
  	return ret;
  }
  
  static ssize_t store_current_governor(struct device *dev,
  				      struct device_attribute *attr,
  				      const char *buf, size_t count)
  {
  	char gov_name[CPUIDLE_NAME_LEN];
  	int ret = -EINVAL;
  	size_t len = count;
  	struct cpuidle_governor *gov;
  
  	if (!len || len >= sizeof(gov_name))
  		return -EINVAL;
  
  	memcpy(gov_name, buf, len);
  	gov_name[len] = '\0';
  	if (gov_name[len - 1] == '\n')
  		gov_name[--len] = '\0';
  
  	mutex_lock(&cpuidle_lock);
  
  	list_for_each_entry(gov, &cpuidle_governors, governor_list) {
  		if (strlen(gov->name) == len && !strcmp(gov->name, gov_name)) {
  			ret = cpuidle_switch_governor(gov);
  			break;
  		}
  	}
  
  	mutex_unlock(&cpuidle_lock);
  
  	if (ret)
  		return ret;
  	else
  		return count;
  }
  
  static DEVICE_ATTR(current_driver, 0444, show_current_driver, NULL);
  static DEVICE_ATTR(current_governor_ro, 0444, show_current_governor, NULL);
  
  static struct attribute *cpuidle_default_attrs[] = {
  	&dev_attr_current_driver.attr,
  	&dev_attr_current_governor_ro.attr,
  	NULL
  };
  
  static DEVICE_ATTR(available_governors, 0444, show_available_governors, NULL);
  static DEVICE_ATTR(current_governor, 0644, show_current_governor,
  		   store_current_governor);
  
  static struct attribute *cpuidle_switch_attrs[] = {
  	&dev_attr_available_governors.attr,
  	&dev_attr_current_driver.attr,
  	&dev_attr_current_governor.attr,
  	NULL
  };
  
  static struct attribute_group cpuidle_attr_group = {
  	.attrs = cpuidle_default_attrs,
  	.name = "cpuidle",
  };
  
  /**
   * cpuidle_add_interface - add CPU global sysfs attributes
   * @dev: the target device
   */
  int cpuidle_add_interface(struct device *dev)
  {
  	if (sysfs_switch)
  		cpuidle_attr_group.attrs = cpuidle_switch_attrs;
  
  	return sysfs_create_group(&dev->kobj, &cpuidle_attr_group);
  }
  
  /**
   * cpuidle_remove_interface - remove CPU global sysfs attributes
   * @dev: the target device
   */
  void cpuidle_remove_interface(struct device *dev)
  {
  	sysfs_remove_group(&dev->kobj, &cpuidle_attr_group);
  }
  
  struct cpuidle_attr {
  	struct attribute attr;
  	ssize_t (*show)(struct cpuidle_device *, char *);
  	ssize_t (*store)(struct cpuidle_device *, const char *, size_t count);
  };
  
  #define define_one_ro(_name, show) \
  	static struct cpuidle_attr attr_##_name = __ATTR(_name, 0444, show, NULL)
  #define define_one_rw(_name, show, store) \
  	static struct cpuidle_attr attr_##_name = __ATTR(_name, 0644, show, store)
  
  #define attr_to_cpuidleattr(a) container_of(a, struct cpuidle_attr, attr)
  
  struct cpuidle_device_kobj {
  	struct cpuidle_device *dev;
  	struct completion kobj_unregister;
  	struct kobject kobj;
  };
  
  static inline struct cpuidle_device *to_cpuidle_device(struct kobject *kobj)
  {
  	struct cpuidle_device_kobj *kdev =
  		container_of(kobj, struct cpuidle_device_kobj, kobj);
  
  	return kdev->dev;
  }
  
  static ssize_t cpuidle_show(struct kobject *kobj, struct attribute *attr,
  			    char *buf)
  {
  	int ret = -EIO;
  	struct cpuidle_device *dev = to_cpuidle_device(kobj);
  	struct cpuidle_attr *cattr = attr_to_cpuidleattr(attr);
  
  	if (cattr->show) {
  		mutex_lock(&cpuidle_lock);
  		ret = cattr->show(dev, buf);
  		mutex_unlock(&cpuidle_lock);
  	}
  	return ret;
  }
  
  static ssize_t cpuidle_store(struct kobject *kobj, struct attribute *attr,
  			     const char *buf, size_t count)
  {
  	int ret = -EIO;
  	struct cpuidle_device *dev = to_cpuidle_device(kobj);
  	struct cpuidle_attr *cattr = attr_to_cpuidleattr(attr);
  
  	if (cattr->store) {
  		mutex_lock(&cpuidle_lock);
  		ret = cattr->store(dev, buf, count);
  		mutex_unlock(&cpuidle_lock);
  	}
  	return ret;
  }
  
  static const struct sysfs_ops cpuidle_sysfs_ops = {
  	.show = cpuidle_show,
  	.store = cpuidle_store,
  };
  
  static void cpuidle_sysfs_release(struct kobject *kobj)
  {
  	struct cpuidle_device_kobj *kdev =
  		container_of(kobj, struct cpuidle_device_kobj, kobj);
  
  	complete(&kdev->kobj_unregister);
  }
  
  static struct kobj_type ktype_cpuidle = {
  	.sysfs_ops = &cpuidle_sysfs_ops,
  	.release = cpuidle_sysfs_release,
  };
  
  struct cpuidle_state_attr {
  	struct attribute attr;
  	ssize_t (*show)(struct cpuidle_state *, \
  					struct cpuidle_state_usage *, char *);
  	ssize_t (*store)(struct cpuidle_state *, \
  			struct cpuidle_state_usage *, const char *, size_t);
  };
  
  #define define_one_state_ro(_name, show) \
  static struct cpuidle_state_attr attr_##_name = __ATTR(_name, 0444, show, NULL)
  
  #define define_one_state_rw(_name, show, store) \
  static struct cpuidle_state_attr attr_##_name = __ATTR(_name, 0644, show, store)
  
  #define define_show_state_function(_name) \
  static ssize_t show_state_##_name(struct cpuidle_state *state, \
  			 struct cpuidle_state_usage *state_usage, char *buf) \
  { \
  	return sprintf(buf, "%u\n", state->_name);\
  }
  
  #define define_show_state_ull_function(_name) \
  static ssize_t show_state_##_name(struct cpuidle_state *state, \
  				  struct cpuidle_state_usage *state_usage, \
  				  char *buf)				\
  { \
  	return sprintf(buf, "%llu\n", state_usage->_name);\
  }
  
  #define define_show_state_str_function(_name) \
  static ssize_t show_state_##_name(struct cpuidle_state *state, \
  				  struct cpuidle_state_usage *state_usage, \
  				  char *buf)				\
  { \
  	if (state->_name[0] == '\0')\
  		return sprintf(buf, "<null>\n");\
  	return sprintf(buf, "%s\n", state->_name);\
  }
  
  #define define_show_state_time_function(_name) \
  static ssize_t show_state_##_name(struct cpuidle_state *state, \
  				  struct cpuidle_state_usage *state_usage, \
  				  char *buf) \
  { \
  	return sprintf(buf, "%llu\n", ktime_to_us(state->_name##_ns)); \
  }
  
  define_show_state_time_function(exit_latency)
  define_show_state_time_function(target_residency)
  define_show_state_function(power_usage)
  define_show_state_ull_function(usage)
  define_show_state_str_function(name)
  define_show_state_str_function(desc)
  define_show_state_ull_function(above)
  define_show_state_ull_function(below)
  
  static ssize_t show_state_time(struct cpuidle_state *state,
  			       struct cpuidle_state_usage *state_usage,
  			       char *buf)
  {
  	return sprintf(buf, "%llu\n", ktime_to_us(state_usage->time_ns));
  }
  
  static ssize_t show_state_disable(struct cpuidle_state *state,
  				  struct cpuidle_state_usage *state_usage,
  				  char *buf)
  {
  	return sprintf(buf, "%llu\n",
  		       state_usage->disable & CPUIDLE_STATE_DISABLED_BY_USER);
  }
  
  static ssize_t store_state_disable(struct cpuidle_state *state,
  				   struct cpuidle_state_usage *state_usage,
  				   const char *buf, size_t size)
  {
  	unsigned int value;
  	int err;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EPERM;
  
  	err = kstrtouint(buf, 0, &value);
  	if (err)
  		return err;
  
  	if (value)
  		state_usage->disable |= CPUIDLE_STATE_DISABLED_BY_USER;
  	else
  		state_usage->disable &= ~CPUIDLE_STATE_DISABLED_BY_USER;
  
  	return size;
  }
  
  static ssize_t show_state_default_status(struct cpuidle_state *state,
  					  struct cpuidle_state_usage *state_usage,
  					  char *buf)
  {
  	return sprintf(buf, "%s\n",
  		       state->flags & CPUIDLE_FLAG_OFF ? "disabled" : "enabled");
  }
  
  define_one_state_ro(name, show_state_name);
  define_one_state_ro(desc, show_state_desc);
  define_one_state_ro(latency, show_state_exit_latency);
  define_one_state_ro(residency, show_state_target_residency);
  define_one_state_ro(power, show_state_power_usage);
  define_one_state_ro(usage, show_state_usage);
  define_one_state_ro(time, show_state_time);
  define_one_state_rw(disable, show_state_disable, store_state_disable);
  define_one_state_ro(above, show_state_above);
  define_one_state_ro(below, show_state_below);
  define_one_state_ro(default_status, show_state_default_status);
  
  static struct attribute *cpuidle_state_default_attrs[] = {
  	&attr_name.attr,
  	&attr_desc.attr,
  	&attr_latency.attr,
  	&attr_residency.attr,
  	&attr_power.attr,
  	&attr_usage.attr,
  	&attr_time.attr,
  	&attr_disable.attr,
  	&attr_above.attr,
  	&attr_below.attr,
  	&attr_default_status.attr,
  	NULL
  };
  
  struct cpuidle_state_kobj {
  	struct cpuidle_state *state;
  	struct cpuidle_state_usage *state_usage;
  	struct completion kobj_unregister;
  	struct kobject kobj;
  	struct cpuidle_device *device;
  };
  
  #ifdef CONFIG_SUSPEND
  #define define_show_state_s2idle_ull_function(_name) \
  static ssize_t show_state_s2idle_##_name(struct cpuidle_state *state, \
  					 struct cpuidle_state_usage *state_usage, \
  					 char *buf)				\
  { \
  	return sprintf(buf, "%llu\n", state_usage->s2idle_##_name);\
  }
  
  define_show_state_s2idle_ull_function(usage);
  define_show_state_s2idle_ull_function(time);
  
  #define define_one_state_s2idle_ro(_name, show) \
  static struct cpuidle_state_attr attr_s2idle_##_name = \
  	__ATTR(_name, 0444, show, NULL)
  
  define_one_state_s2idle_ro(usage, show_state_s2idle_usage);
  define_one_state_s2idle_ro(time, show_state_s2idle_time);
  
  static struct attribute *cpuidle_state_s2idle_attrs[] = {
  	&attr_s2idle_usage.attr,
  	&attr_s2idle_time.attr,
  	NULL
  };
  
  static const struct attribute_group cpuidle_state_s2idle_group = {
  	.name	= "s2idle",
  	.attrs	= cpuidle_state_s2idle_attrs,
  };
  
  static void cpuidle_add_s2idle_attr_group(struct cpuidle_state_kobj *kobj)
  {
  	int ret;
  
  	if (!kobj->state->enter_s2idle)
  		return;
  
  	ret = sysfs_create_group(&kobj->kobj, &cpuidle_state_s2idle_group);
  	if (ret)
  		pr_debug("%s: sysfs attribute group not created\n", __func__);
  }
  
  static void cpuidle_remove_s2idle_attr_group(struct cpuidle_state_kobj *kobj)
  {
  	if (kobj->state->enter_s2idle)
  		sysfs_remove_group(&kobj->kobj, &cpuidle_state_s2idle_group);
  }
  #else
  static inline void cpuidle_add_s2idle_attr_group(struct cpuidle_state_kobj *kobj) { }
  static inline void cpuidle_remove_s2idle_attr_group(struct cpuidle_state_kobj *kobj) { }
  #endif /* CONFIG_SUSPEND */
  
  #define kobj_to_state_obj(k) container_of(k, struct cpuidle_state_kobj, kobj)
  #define kobj_to_state(k) (kobj_to_state_obj(k)->state)
  #define kobj_to_state_usage(k) (kobj_to_state_obj(k)->state_usage)
  #define kobj_to_device(k) (kobj_to_state_obj(k)->device)
  #define attr_to_stateattr(a) container_of(a, struct cpuidle_state_attr, attr)
  
  static ssize_t cpuidle_state_show(struct kobject *kobj, struct attribute *attr,
  				  char * buf)
  {
  	int ret = -EIO;
  	struct cpuidle_state *state = kobj_to_state(kobj);
  	struct cpuidle_state_usage *state_usage = kobj_to_state_usage(kobj);
  	struct cpuidle_state_attr * cattr = attr_to_stateattr(attr);
  
  	if (cattr->show)
  		ret = cattr->show(state, state_usage, buf);
  
  	return ret;
  }
  
  static ssize_t cpuidle_state_store(struct kobject *kobj, struct attribute *attr,
  				   const char *buf, size_t size)
  {
  	int ret = -EIO;
  	struct cpuidle_state *state = kobj_to_state(kobj);
  	struct cpuidle_state_usage *state_usage = kobj_to_state_usage(kobj);
  	struct cpuidle_state_attr *cattr = attr_to_stateattr(attr);
  	struct cpuidle_device *dev = kobj_to_device(kobj);
  
  	if (cattr->store)
  		ret = cattr->store(state, state_usage, buf, size);
  
  	/* reset poll time cache */
  	dev->poll_limit_ns = 0;
  
  	return ret;
  }
  
  static const struct sysfs_ops cpuidle_state_sysfs_ops = {
  	.show = cpuidle_state_show,
  	.store = cpuidle_state_store,
  };
  
  static void cpuidle_state_sysfs_release(struct kobject *kobj)
  {
  	struct cpuidle_state_kobj *state_obj = kobj_to_state_obj(kobj);
  
  	complete(&state_obj->kobj_unregister);
  }
  
  static struct kobj_type ktype_state_cpuidle = {
  	.sysfs_ops = &cpuidle_state_sysfs_ops,
  	.default_attrs = cpuidle_state_default_attrs,
  	.release = cpuidle_state_sysfs_release,
  };
  
  static inline void cpuidle_free_state_kobj(struct cpuidle_device *device, int i)
  {
  	cpuidle_remove_s2idle_attr_group(device->kobjs[i]);
  	kobject_put(&device->kobjs[i]->kobj);
  	wait_for_completion(&device->kobjs[i]->kobj_unregister);
  	kfree(device->kobjs[i]);
  	device->kobjs[i] = NULL;
  }
  
  /**
   * cpuidle_add_state_sysfs - adds cpuidle states sysfs attributes
   * @device: the target device
   */
  static int cpuidle_add_state_sysfs(struct cpuidle_device *device)
  {
  	int i, ret = -ENOMEM;
  	struct cpuidle_state_kobj *kobj;
  	struct cpuidle_device_kobj *kdev = device->kobj_dev;
  	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(device);
  
  	/* state statistics */
  	for (i = 0; i < drv->state_count; i++) {
  		kobj = kzalloc(sizeof(struct cpuidle_state_kobj), GFP_KERNEL);
  		if (!kobj) {
  			ret = -ENOMEM;
  			goto error_state;
  		}
  		kobj->state = &drv->states[i];
  		kobj->state_usage = &device->states_usage[i];
  		kobj->device = device;
  		init_completion(&kobj->kobj_unregister);
  
  		ret = kobject_init_and_add(&kobj->kobj, &ktype_state_cpuidle,
  					   &kdev->kobj, "state%d", i);
  		if (ret) {
  			kfree(kobj);
  			goto error_state;
  		}
  		cpuidle_add_s2idle_attr_group(kobj);
  		kobject_uevent(&kobj->kobj, KOBJ_ADD);
  		device->kobjs[i] = kobj;
  	}
  
  	return 0;
  
  error_state:
  	for (i = i - 1; i >= 0; i--)
  		cpuidle_free_state_kobj(device, i);
  	return ret;
  }
  
  /**
   * cpuidle_remove_driver_sysfs - removes the cpuidle states sysfs attributes
   * @device: the target device
   */
  static void cpuidle_remove_state_sysfs(struct cpuidle_device *device)
  {
  	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(device);
  	int i;
  
  	for (i = 0; i < drv->state_count; i++)
  		cpuidle_free_state_kobj(device, i);
  }
  
  #ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
  #define kobj_to_driver_kobj(k) container_of(k, struct cpuidle_driver_kobj, kobj)
  #define attr_to_driver_attr(a) container_of(a, struct cpuidle_driver_attr, attr)
  
  #define define_one_driver_ro(_name, show)                       \
  	static struct cpuidle_driver_attr attr_driver_##_name = \
  		__ATTR(_name, 0444, show, NULL)
  
  struct cpuidle_driver_kobj {
  	struct cpuidle_driver *drv;
  	struct completion kobj_unregister;
  	struct kobject kobj;
  };
  
  struct cpuidle_driver_attr {
  	struct attribute attr;
  	ssize_t (*show)(struct cpuidle_driver *, char *);
  	ssize_t (*store)(struct cpuidle_driver *, const char *, size_t);
  };
  
  static ssize_t show_driver_name(struct cpuidle_driver *drv, char *buf)
  {
  	ssize_t ret;
  
  	spin_lock(&cpuidle_driver_lock);
  	ret = sprintf(buf, "%s\n", drv ? drv->name : "none");
  	spin_unlock(&cpuidle_driver_lock);
  
  	return ret;
  }
  
  static void cpuidle_driver_sysfs_release(struct kobject *kobj)
  {
  	struct cpuidle_driver_kobj *driver_kobj = kobj_to_driver_kobj(kobj);
  	complete(&driver_kobj->kobj_unregister);
  }
  
  static ssize_t cpuidle_driver_show(struct kobject *kobj, struct attribute *attr,
  				   char *buf)
  {
  	int ret = -EIO;
  	struct cpuidle_driver_kobj *driver_kobj = kobj_to_driver_kobj(kobj);
  	struct cpuidle_driver_attr *dattr = attr_to_driver_attr(attr);
  
  	if (dattr->show)
  		ret = dattr->show(driver_kobj->drv, buf);
  
  	return ret;
  }
  
  static ssize_t cpuidle_driver_store(struct kobject *kobj, struct attribute *attr,
  				    const char *buf, size_t size)
  {
  	int ret = -EIO;
  	struct cpuidle_driver_kobj *driver_kobj = kobj_to_driver_kobj(kobj);
  	struct cpuidle_driver_attr *dattr = attr_to_driver_attr(attr);
  
  	if (dattr->store)
  		ret = dattr->store(driver_kobj->drv, buf, size);
  
  	return ret;
  }
  
  define_one_driver_ro(name, show_driver_name);
  
  static const struct sysfs_ops cpuidle_driver_sysfs_ops = {
  	.show = cpuidle_driver_show,
  	.store = cpuidle_driver_store,
  };
  
  static struct attribute *cpuidle_driver_default_attrs[] = {
  	&attr_driver_name.attr,
  	NULL
  };
  
  static struct kobj_type ktype_driver_cpuidle = {
  	.sysfs_ops = &cpuidle_driver_sysfs_ops,
  	.default_attrs = cpuidle_driver_default_attrs,
  	.release = cpuidle_driver_sysfs_release,
  };
  
  /**
   * cpuidle_add_driver_sysfs - adds the driver name sysfs attribute
   * @dev: the target device
   */
  static int cpuidle_add_driver_sysfs(struct cpuidle_device *dev)
  {
  	struct cpuidle_driver_kobj *kdrv;
  	struct cpuidle_device_kobj *kdev = dev->kobj_dev;
  	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
  	int ret;
  
  	kdrv = kzalloc(sizeof(*kdrv), GFP_KERNEL);
  	if (!kdrv)
  		return -ENOMEM;
  
  	kdrv->drv = drv;
  	init_completion(&kdrv->kobj_unregister);
  
  	ret = kobject_init_and_add(&kdrv->kobj, &ktype_driver_cpuidle,
  				   &kdev->kobj, "driver");
  	if (ret) {
  		kfree(kdrv);
  		return ret;
  	}
  
  	kobject_uevent(&kdrv->kobj, KOBJ_ADD);
  	dev->kobj_driver = kdrv;
  
  	return ret;
  }
  
  /**
   * cpuidle_remove_driver_sysfs - removes the driver name sysfs attribute
   * @dev: the target device
   */
  static void cpuidle_remove_driver_sysfs(struct cpuidle_device *dev)
  {
  	struct cpuidle_driver_kobj *kdrv = dev->kobj_driver;
  	kobject_put(&kdrv->kobj);
  	wait_for_completion(&kdrv->kobj_unregister);
  	kfree(kdrv);
  }
  #else
  static inline int cpuidle_add_driver_sysfs(struct cpuidle_device *dev)
  {
  	return 0;
  }
  
  static inline void cpuidle_remove_driver_sysfs(struct cpuidle_device *dev)
  {
  	;
  }
  #endif
  
  /**
   * cpuidle_add_device_sysfs - adds device specific sysfs attributes
   * @device: the target device
   */
  int cpuidle_add_device_sysfs(struct cpuidle_device *device)
  {
  	int ret;
  
  	ret = cpuidle_add_state_sysfs(device);
  	if (ret)
  		return ret;
  
  	ret = cpuidle_add_driver_sysfs(device);
  	if (ret)
  		cpuidle_remove_state_sysfs(device);
  	return ret;
  }
  
  /**
   * cpuidle_remove_device_sysfs : removes device specific sysfs attributes
   * @device : the target device
   */
  void cpuidle_remove_device_sysfs(struct cpuidle_device *device)
  {
  	cpuidle_remove_driver_sysfs(device);
  	cpuidle_remove_state_sysfs(device);
  }
  
  /**
   * cpuidle_add_sysfs - creates a sysfs instance for the target device
   * @dev: the target device
   */
  int cpuidle_add_sysfs(struct cpuidle_device *dev)
  {
  	struct cpuidle_device_kobj *kdev;
  	struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
  	int error;
  
  	/*
  	 * Return if cpu_device is not setup for this CPU.
  	 *
  	 * This could happen if the arch did not set up cpu_device
  	 * since this CPU is not in cpu_present mask and the
  	 * driver did not send a correct CPU mask during registration.
  	 * Without this check we would end up passing bogus
  	 * value for &cpu_dev->kobj in kobject_init_and_add()
  	 */
  	if (!cpu_dev)
  		return -ENODEV;
  
  	kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
  	if (!kdev)
  		return -ENOMEM;
  	kdev->dev = dev;
  	dev->kobj_dev = kdev;
  
  	init_completion(&kdev->kobj_unregister);
  
  	error = kobject_init_and_add(&kdev->kobj, &ktype_cpuidle, &cpu_dev->kobj,
  				   "cpuidle");
  	if (error) {
  		kfree(kdev);
  		return error;
  	}
  
  	kobject_uevent(&kdev->kobj, KOBJ_ADD);
  
  	return 0;
  }
  
  /**
   * cpuidle_remove_sysfs - deletes a sysfs instance on the target device
   * @dev: the target device
   */
  void cpuidle_remove_sysfs(struct cpuidle_device *dev)
  {
  	struct cpuidle_device_kobj *kdev = dev->kobj_dev;
  
  	kobject_put(&kdev->kobj);
  	wait_for_completion(&kdev->kobj_unregister);
  	kfree(kdev);
  }
  