core.c

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/*
 * drivers/base/core.c - core driver model code (device registration, etc)
 *
 * Copyright (c) 2002-3 Patrick Mochel
 * Copyright (c) 2002-3 Open Source Development Labs
 * Copyright (c) 2006 Greg Kroah-Hartman <[email protected]>
 * Copyright (c) 2006 Novell, Inc.
 *
 * This file is released under the GPLv2
 *
 */

#include <linux/device.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/kdev_t.h>
#include <linux/notifier.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/genhd.h>
#include <linux/kallsyms.h>
#include <linux/mutex.h>
#include <linux/async.h>
#include <linux/pm_runtime.h>
#include <linux/netdevice.h>

#include "base.h"
#include "power/power.h"

#ifdef CONFIG_SYSFS_DEPRECATED
#ifdef CONFIG_SYSFS_DEPRECATED_V2
long sysfs_deprecated = 1;
#else
long sysfs_deprecated = 0;
#endif
static __init int sysfs_deprecated_setup(char *arg)
{
    return strict_strtol(arg, 10, &sysfs_deprecated);
}
early_param("sysfs.deprecated", sysfs_deprecated_setup);
#endif

int (*platform_notify)(struct device *dev) = NULL;
int (*platform_notify_remove)(struct device *dev) = NULL;
static struct kobject *dev_kobj;
struct kobject *sysfs_dev_char_kobj;
struct kobject *sysfs_dev_block_kobj;

#ifdef CONFIG_BLOCK
static inline int device_is_not_partition(struct device *dev)
{
    return !(dev->type == &part_type);
}
#else
static inline int device_is_not_partition(struct device *dev)
{
    return 1;
}
#endif

const char *dev_driver_string(const struct device *dev)
{
    struct device_driver *drv;

    /* dev->driver can change to NULL underneath us because of unbinding,
     * so be careful about accessing it.  dev->bus and dev->class should
     * never change once they are set, so they don't need special care.
     */
    drv = ACCESS_ONCE(dev->driver);
    return drv ? drv->name :
            (dev->bus ? dev->bus->name :
            (dev->class ? dev->class->name : ""));
}
EXPORT_SYMBOL(dev_driver_string);

#define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)

static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr,
                 char *buf)
{
    struct device_attribute *dev_attr = to_dev_attr(attr);
    struct device *dev = kobj_to_dev(kobj);
    ssize_t ret = -EIO;

    if (dev_attr->show)
        ret = dev_attr->show(dev, dev_attr, buf);
    if (ret >= (ssize_t)PAGE_SIZE) {
        print_symbol("dev_attr_show: %s returned bad count\n",
                (unsigned long)dev_attr->show);
    }
    return ret;
}

static ssize_t dev_attr_store(struct kobject *kobj, struct attribute *attr,
                  const char *buf, size_t count)
{
    struct device_attribute *dev_attr = to_dev_attr(attr);
    struct device *dev = kobj_to_dev(kobj);
    ssize_t ret = -EIO;

    if (dev_attr->store)
        ret = dev_attr->store(dev, dev_attr, buf, count);
    return ret;
}

static const struct sysfs_ops dev_sysfs_ops = {
    .show   = dev_attr_show,
    .store  = dev_attr_store,
};

#define to_ext_attr(x) container_of(x, struct dev_ext_attribute, attr)

ssize_t device_store_ulong(struct device *dev,
               struct device_attribute *attr,
               const char *buf, size_t size)
{
    struct dev_ext_attribute *ea = to_ext_attr(attr);
    char *end;
    unsigned long new = simple_strtoul(buf, &end, 0);
    if (end == buf)
        return -EINVAL;
    *(unsigned long *)(ea->var) = new;
    /* Always return full write size even if we didn't consume all */
    return size;
}
EXPORT_SYMBOL_GPL(device_store_ulong);

ssize_t device_show_ulong(struct device *dev,
              struct device_attribute *attr,
              char *buf)
{
    struct dev_ext_attribute *ea = to_ext_attr(attr);
    return snprintf(buf, PAGE_SIZE, "%lx\n", *(unsigned long *)(ea->var));
}
EXPORT_SYMBOL_GPL(device_show_ulong);

ssize_t device_store_int(struct device *dev,
             struct device_attribute *attr,
             const char *buf, size_t size)
{
    struct dev_ext_attribute *ea = to_ext_attr(attr);
    char *end;
    long new = simple_strtol(buf, &end, 0);
    if (end == buf || new > INT_MAX || new < INT_MIN)
        return -EINVAL;
    *(int *)(ea->var) = new;
    /* Always return full write size even if we didn't consume all */
    return size;
}
EXPORT_SYMBOL_GPL(device_store_int);

ssize_t device_show_int(struct device *dev,
            struct device_attribute *attr,
            char *buf)
{
    struct dev_ext_attribute *ea = to_ext_attr(attr);

    return snprintf(buf, PAGE_SIZE, "%d\n", *(int *)(ea->var));
}
EXPORT_SYMBOL_GPL(device_show_int);

static void device_release(struct kobject *kobj)
{
    struct device *dev = kobj_to_dev(kobj);
    struct device_private *p = dev->p;

    /*
     * Some platform devices are driven without driver attached
     * and managed resources may have been acquired.  Make sure
     * all resources are released.
     *
     * Drivers still can add resources into device after device
     * is deleted but alive, so release devres here to avoid
     * possible memory leak.
     */
    devres_release_all(dev);

    if (dev->release)
        dev->release(dev);
    else if (dev->type && dev->type->release)
        dev->type->release(dev);
    else if (dev->class && dev->class->dev_release)
        dev->class->dev_release(dev);
    else
        WARN(1, KERN_ERR "Device '%s' does not have a release() "
            "function, it is broken and must be fixed.\n",
            dev_name(dev));
    kfree(p);
}

static const void *device_namespace(struct kobject *kobj)
{
    struct device *dev = kobj_to_dev(kobj);
    const void *ns = NULL;

    if (dev->class && dev->class->ns_type)
        ns = dev->class->namespace(dev);

    return ns;
}

static struct kobj_type device_ktype = {
    .release    = device_release,
    .sysfs_ops  = &dev_sysfs_ops,
    .namespace  = device_namespace,
};


static int dev_uevent_filter(struct kset *kset, struct kobject *kobj)
{
    struct kobj_type *ktype = get_ktype(kobj);

    if (ktype == &device_ktype) {
        struct device *dev = kobj_to_dev(kobj);
        if (dev->bus)
            return 1;
        if (dev->class)
            return 1;
    }
    return 0;
}

static const char *dev_uevent_name(struct kset *kset, struct kobject *kobj)
{
    struct device *dev = kobj_to_dev(kobj);

    if (dev->bus)
        return dev->bus->name;
    if (dev->class)
        return dev->class->name;
    return NULL;
}

static int dev_uevent(struct kset *kset, struct kobject *kobj,
              struct kobj_uevent_env *env)
{
    struct device *dev = kobj_to_dev(kobj);
    int retval = 0;

    /* add device node properties if present */
    if (MAJOR(dev->devt)) {
        const char *tmp;
        const char *name;
        umode_t mode = 0;

        add_uevent_var(env, "MAJOR=%u", MAJOR(dev->devt));
        add_uevent_var(env, "MINOR=%u", MINOR(dev->devt));
        name = device_get_devnode(dev, &mode, &tmp);
        if (name) {
            add_uevent_var(env, "DEVNAME=%s", name);
            kfree(tmp);
            if (mode)
                add_uevent_var(env, "DEVMODE=%#o", mode & 0777);
        }
    }

    if (dev->type && dev->type->name)
        add_uevent_var(env, "DEVTYPE=%s", dev->type->name);

    if (dev->driver)
        add_uevent_var(env, "DRIVER=%s", dev->driver->name);

    /* Add common DT information about the device */
    of_device_uevent(dev, env);

    /* have the bus specific function add its stuff */
    if (dev->bus && dev->bus->uevent) {
        retval = dev->bus->uevent(dev, env);
        if (retval)
            pr_debug("device: '%s': %s: bus uevent() returned %d\n",
                 dev_name(dev), __func__, retval);
    }

    /* have the class specific function add its stuff */
    if (dev->class && dev->class->dev_uevent) {
        retval = dev->class->dev_uevent(dev, env);
        if (retval)
            pr_debug("device: '%s': %s: class uevent() "
                 "returned %d\n", dev_name(dev),
                 __func__, retval);
    }

    /* have the device type specific function add its stuff */
    if (dev->type && dev->type->uevent) {
        retval = dev->type->uevent(dev, env);
        if (retval)
            pr_debug("device: '%s': %s: dev_type uevent() "
                 "returned %d\n", dev_name(dev),
                 __func__, retval);
    }

    return retval;
}

static const struct kset_uevent_ops device_uevent_ops = {
    .filter =   dev_uevent_filter,
    .name =     dev_uevent_name,
    .uevent =   dev_uevent,
};

static ssize_t show_uevent(struct device *dev, struct device_attribute *attr,
               char *buf)
{
    struct kobject *top_kobj;
    struct kset *kset;
    struct kobj_uevent_env *env = NULL;
    int i;
    size_t count = 0;
    int retval;

    /* search the kset, the device belongs to */
    top_kobj = &dev->kobj;
    while (!top_kobj->kset && top_kobj->parent)
        top_kobj = top_kobj->parent;
    if (!top_kobj->kset)
        goto out;

    kset = top_kobj->kset;
    if (!kset->uevent_ops || !kset->uevent_ops->uevent)
        goto out;

    /* respect filter */
    if (kset->uevent_ops && kset->uevent_ops->filter)
        if (!kset->uevent_ops->filter(kset, &dev->kobj))
            goto out;

    env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
    if (!env)
        return -ENOMEM;

    /* let the kset specific function add its keys */
    retval = kset->uevent_ops->uevent(kset, &dev->kobj, env);
    if (retval)
        goto out;

    /* copy keys to file */
    for (i = 0; i < env->envp_idx; i++)
        count += sprintf(&buf[count], "%s\n", env->envp[i]);
out:
    kfree(env);
    return count;
}

static ssize_t store_uevent(struct device *dev, struct device_attribute *attr,
                const char *buf, size_t count)
{
    enum kobject_action action;

    if (kobject_action_type(buf, count, &action) == 0)
        kobject_uevent(&dev->kobj, action);
    else
        dev_err(dev, "uevent: unknown action-string\n");
    return count;
}

static struct device_attribute uevent_attr =
    __ATTR(uevent, S_IRUGO | S_IWUSR, show_uevent, store_uevent);

static int device_add_attributes(struct device *dev,
                 struct device_attribute *attrs)
{
    int error = 0;
    int i;

    if (attrs) {
        for (i = 0; attr_name(attrs[i]); i++) {
            error = device_create_file(dev, &attrs[i]);
            if (error)
                break;
        }
        if (error)
            while (--i >= 0)
                device_remove_file(dev, &attrs[i]);
    }
    return error;
}

static void device_remove_attributes(struct device *dev,
                     struct device_attribute *attrs)
{
    int i;

    if (attrs)
        for (i = 0; attr_name(attrs[i]); i++)
            device_remove_file(dev, &attrs[i]);
}

static int device_add_bin_attributes(struct device *dev,
                     struct bin_attribute *attrs)
{
    int error = 0;
    int i;

    if (attrs) {
        for (i = 0; attr_name(attrs[i]); i++) {
            error = device_create_bin_file(dev, &attrs[i]);
            if (error)
                break;
        }
        if (error)
            while (--i >= 0)
                device_remove_bin_file(dev, &attrs[i]);
    }
    return error;
}

static void device_remove_bin_attributes(struct device *dev,
                     struct bin_attribute *attrs)
{
    int i;

    if (attrs)
        for (i = 0; attr_name(attrs[i]); i++)
            device_remove_bin_file(dev, &attrs[i]);
}

static int device_add_groups(struct device *dev,
                 const struct attribute_group **groups)
{
    int error = 0;
    int i;

    if (groups) {
        for (i = 0; groups[i]; i++) {
            error = sysfs_create_group(&dev->kobj, groups[i]);
            if (error) {
                while (--i >= 0)
                    sysfs_remove_group(&dev->kobj,
                               groups[i]);
                break;
            }
        }
    }
    return error;
}

static void device_remove_groups(struct device *dev,
                 const struct attribute_group **groups)
{
    int i;

    if (groups)
        for (i = 0; groups[i]; i++)
            sysfs_remove_group(&dev->kobj, groups[i]);
}

static int device_add_attrs(struct device *dev)
{
    struct class *class = dev->class;
    const struct device_type *type = dev->type;
    int error;

    if (class) {
        error = device_add_attributes(dev, class->dev_attrs);
        if (error)
            return error;
        error = device_add_bin_attributes(dev, class->dev_bin_attrs);
        if (error)
            goto err_remove_class_attrs;
    }

    if (type) {
        error = device_add_groups(dev, type->groups);
        if (error)
            goto err_remove_class_bin_attrs;
    }

    error = device_add_groups(dev, dev->groups);
    if (error)
        goto err_remove_type_groups;

    return 0;

 err_remove_type_groups:
    if (type)
        device_remove_groups(dev, type->groups);
 err_remove_class_bin_attrs:
    if (class)
        device_remove_bin_attributes(dev, class->dev_bin_attrs);
 err_remove_class_attrs:
    if (class)
        device_remove_attributes(dev, class->dev_attrs);

    return error;
}

static void device_remove_attrs(struct device *dev)
{
    struct class *class = dev->class;
    const struct device_type *type = dev->type;

    device_remove_groups(dev, dev->groups);

    if (type)
        device_remove_groups(dev, type->groups);

    if (class) {
        device_remove_attributes(dev, class->dev_attrs);
        device_remove_bin_attributes(dev, class->dev_bin_attrs);
    }
}


static ssize_t show_dev(struct device *dev, struct device_attribute *attr,
            char *buf)
{
    return print_dev_t(buf, dev->devt);
}

static struct device_attribute devt_attr =
    __ATTR(dev, S_IRUGO, show_dev, NULL);

/* /sys/devices/ */
struct kset *devices_kset;

int device_create_file(struct device *dev,
               const struct device_attribute *attr)
{
    int error = 0;
    if (dev)
        error = sysfs_create_file(&dev->kobj, &attr->attr);
    return error;
}

void device_remove_file(struct device *dev,
            const struct device_attribute *attr)
{
    if (dev)
        sysfs_remove_file(&dev->kobj, &attr->attr);
}

int device_create_bin_file(struct device *dev,
               const struct bin_attribute *attr)
{
    int error = -EINVAL;
    if (dev)
        error = sysfs_create_bin_file(&dev->kobj, attr);
    return error;
}
EXPORT_SYMBOL_GPL(device_create_bin_file);

void device_remove_bin_file(struct device *dev,
                const struct bin_attribute *attr)
{
    if (dev)
        sysfs_remove_bin_file(&dev->kobj, attr);
}
EXPORT_SYMBOL_GPL(device_remove_bin_file);

int device_schedule_callback_owner(struct device *dev,
        void (*func)(struct device *), struct module *owner)
{
    return sysfs_schedule_callback(&dev->kobj,
            (void (*)(void *)) func, dev, owner);
}
EXPORT_SYMBOL_GPL(device_schedule_callback_owner);

static void klist_children_get(struct klist_node *n)
{
    struct device_private *p = to_device_private_parent(n);
    struct device *dev = p->device;

    get_device(dev);
}

static void klist_children_put(struct klist_node *n)
{
    struct device_private *p = to_device_private_parent(n);
    struct device *dev = p->device;

    put_device(dev);
}

void device_initialize(struct device *dev)
{
    dev->kobj.kset = devices_kset;
    kobject_init(&dev->kobj, &device_ktype);
    INIT_LIST_HEAD(&dev->dma_pools);
    mutex_init(&dev->mutex);
    lockdep_set_novalidate_class(&dev->mutex);
    spin_lock_init(&dev->devres_lock);
    INIT_LIST_HEAD(&dev->devres_head);
    device_pm_init(dev);
    set_dev_node(dev, -1);
}

static struct kobject *virtual_device_parent(struct device *dev)
{
    static struct kobject *virtual_dir = NULL;

    if (!virtual_dir)
        virtual_dir = kobject_create_and_add("virtual",
                             &devices_kset->kobj);

    return virtual_dir;
}

struct class_dir {
    struct kobject kobj;
    struct class *class;
};

#define to_class_dir(obj) container_of(obj, struct class_dir, kobj)

static void class_dir_release(struct kobject *kobj)
{
    struct class_dir *dir = to_class_dir(kobj);
    kfree(dir);
}

static const
struct kobj_ns_type_operations *class_dir_child_ns_type(struct kobject *kobj)
{
    struct class_dir *dir = to_class_dir(kobj);
    return dir->class->ns_type;
}

static struct kobj_type class_dir_ktype = {
    .release    = class_dir_release,
    .sysfs_ops  = &kobj_sysfs_ops,
    .child_ns_type  = class_dir_child_ns_type
};

static struct kobject *
class_dir_create_and_add(struct class *class, struct kobject *parent_kobj)
{
    struct class_dir *dir;
    int retval;

    dir = kzalloc(sizeof(*dir), GFP_KERNEL);
    if (!dir)
        return NULL;

    dir->class = class;
    kobject_init(&dir->kobj, &class_dir_ktype);

    dir->kobj.kset = &class->p->glue_dirs;

    retval = kobject_add(&dir->kobj, parent_kobj, "%s", class->name);
    if (retval < 0) {
        kobject_put(&dir->kobj);
        return NULL;
    }
    return &dir->kobj;
}


static struct kobject *get_device_parent(struct device *dev,
                     struct device *parent)
{
    if (dev->class) {
        static DEFINE_MUTEX(gdp_mutex);
        struct kobject *kobj = NULL;
        struct kobject *parent_kobj;
        struct kobject *k;

#ifdef CONFIG_BLOCK
        /* block disks show up in /sys/block */
        if (sysfs_deprecated && dev->class == &block_class) {
            if (parent && parent->class == &block_class)
                return &parent->kobj;
            return &block_class.p->subsys.kobj;
        }
#endif

        /*
         * If we have no parent, we live in "virtual".
         * Class-devices with a non class-device as parent, live
         * in a "glue" directory to prevent namespace collisions.
         */
        if (parent == NULL)
            parent_kobj = virtual_device_parent(dev);
        else if (parent->class && !dev->class->ns_type)
            return &parent->kobj;
        else
            parent_kobj = &parent->kobj;

        mutex_lock(&gdp_mutex);

        /* find our class-directory at the parent and reference it */
        spin_lock(&dev->class->p->glue_dirs.list_lock);
        list_for_each_entry(k, &dev->class->p->glue_dirs.list, entry)
            if (k->parent == parent_kobj) {
                kobj = kobject_get(k);
                break;
            }
        spin_unlock(&dev->class->p->glue_dirs.list_lock);
        if (kobj) {
            mutex_unlock(&gdp_mutex);
            return kobj;
        }

        /* or create a new class-directory at the parent device */
        k = class_dir_create_and_add(dev->class, parent_kobj);
        /* do not emit an uevent for this simple "glue" directory */
        mutex_unlock(&gdp_mutex);
        return k;
    }

    /* subsystems can specify a default root directory for their devices */
    if (!parent && dev->bus && dev->bus->dev_root)
        return &dev->bus->dev_root->kobj;

    if (parent)
        return &parent->kobj;
    return NULL;
}

static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
{
    /* see if we live in a "glue" directory */
    if (!glue_dir || !dev->class ||
        glue_dir->kset != &dev->class->p->glue_dirs)
        return;

    kobject_put(glue_dir);
}

static void cleanup_device_parent(struct device *dev)
{
    cleanup_glue_dir(dev, dev->kobj.parent);
}

static int device_add_class_symlinks(struct device *dev)
{
    int error;

    if (!dev->class)
        return 0;

    error = sysfs_create_link(&dev->kobj,
                  &dev->class->p->subsys.kobj,
                  "subsystem");
    if (error)
        goto out;

    if (dev->parent && device_is_not_partition(dev)) {
        error = sysfs_create_link(&dev->kobj, &dev->parent->kobj,
                      "device");
        if (error)
            goto out_subsys;
    }

#ifdef CONFIG_BLOCK
    /* /sys/block has directories and does not need symlinks */
    if (sysfs_deprecated && dev->class == &block_class)
        return 0;
#endif

    /* link in the class directory pointing to the device */
    error = sysfs_create_link(&dev->class->p->subsys.kobj,
                  &dev->kobj, dev_name(dev));
    if (error)
        goto out_device;

    return 0;

out_device:
    sysfs_remove_link(&dev->kobj, "device");

out_subsys:
    sysfs_remove_link(&dev->kobj, "subsystem");
out:
    return error;
}

static void device_remove_class_symlinks(struct device *dev)
{
    if (!dev->class)
        return;

    if (dev->parent && device_is_not_partition(dev))
        sysfs_remove_link(&dev->kobj, "device");
    sysfs_remove_link(&dev->kobj, "subsystem");
#ifdef CONFIG_BLOCK
    if (sysfs_deprecated && dev->class == &block_class)
        return;
#endif
    sysfs_delete_link(&dev->class->p->subsys.kobj, &dev->kobj, dev_name(dev));
}

int dev_set_name(struct device *dev, const char *fmt, ...)
{
    va_list vargs;
    int err;

    va_start(vargs, fmt);
    err = kobject_set_name_vargs(&dev->kobj, fmt, vargs);
    va_end(vargs);
    return err;
}
EXPORT_SYMBOL_GPL(dev_set_name);

static struct kobject *device_to_dev_kobj(struct device *dev)
{
    struct kobject *kobj;

    if (dev->class)
        kobj = dev->class->dev_kobj;
    else
        kobj = sysfs_dev_char_kobj;

    return kobj;
}

static int device_create_sys_dev_entry(struct device *dev)
{
    struct kobject *kobj = device_to_dev_kobj(dev);
    int error = 0;
    char devt_str[15];

    if (kobj) {
        format_dev_t(devt_str, dev->devt);
        error = sysfs_create_link(kobj, &dev->kobj, devt_str);
    }

    return error;
}

static void device_remove_sys_dev_entry(struct device *dev)
{
    struct kobject *kobj = device_to_dev_kobj(dev);
    char devt_str[15];

    if (kobj) {
        format_dev_t(devt_str, dev->devt);
        sysfs_remove_link(kobj, devt_str);
    }
}

int device_private_init(struct device *dev)
{
    dev->p = kzalloc(sizeof(*dev->p), GFP_KERNEL);
    if (!dev->p)
        return -ENOMEM;
    dev->p->device = dev;
    klist_init(&dev->p->klist_children, klist_children_get,
           klist_children_put);
    INIT_LIST_HEAD(&dev->p->deferred_probe);
    return 0;
}

int device_add(struct device *dev)
{
    struct device *parent = NULL;
    struct kobject *kobj;
    struct class_interface *class_intf;
    int error = -EINVAL;

    dev = get_device(dev);
    if (!dev)
        goto done;

    if (!dev->p) {
        error = device_private_init(dev);
        if (error)
            goto done;
    }

    /*
     * for statically allocated devices, which should all be converted
     * some day, we need to initialize the name. We prevent reading back
     * the name, and force the use of dev_name()
     */
    if (dev->init_name) {
        dev_set_name(dev, "%s", dev->init_name);
        dev->init_name = NULL;
    }

    /* subsystems can specify simple device enumeration */
    if (!dev_name(dev) && dev->bus && dev->bus->dev_name)
        dev_set_name(dev, "%s%u", dev->bus->dev_name, dev->id);

    if (!dev_name(dev)) {
        error = -EINVAL;
        goto name_error;
    }

    pr_debug("device: '%s': %s\n", dev_name(dev), __func__);

    parent = get_device(dev->parent);
    kobj = get_device_parent(dev, parent);
    if (kobj)
        dev->kobj.parent = kobj;

    /* use parent numa_node */
    if (parent)
        set_dev_node(dev, dev_to_node(parent));

    /* first, register with generic layer. */
    /* we require the name to be set before, and pass NULL */
    error = kobject_add(&dev->kobj, dev->kobj.parent, NULL);
    if (error)
        goto Error;

    /* notify platform of device entry */
    if (platform_notify)
        platform_notify(dev);

    error = device_create_file(dev, &uevent_attr);
    if (error)
        goto attrError;

    if (MAJOR(dev->devt)) {
        error = device_create_file(dev, &devt_attr);
        if (error)
            goto ueventattrError;

        error = device_create_sys_dev_entry(dev);
        if (error)
            goto devtattrError;

        devtmpfs_create_node(dev);
    }

    error = device_add_class_symlinks(dev);
    if (error)
        goto SymlinkError;
    error = device_add_attrs(dev);
    if (error)
        goto AttrsError;
    error = bus_add_device(dev);
    if (error)
        goto BusError;
    error = dpm_sysfs_add(dev);
    if (error)
        goto DPMError;
    device_pm_add(dev);

    /* Notify clients of device addition.  This call must come
     * after dpm_sysfs_add() and before kobject_uevent().
     */
    if (dev->bus)
        blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
                         BUS_NOTIFY_ADD_DEVICE, dev);

    kobject_uevent(&dev->kobj, KOBJ_ADD);
    bus_probe_device(dev);
    if (parent)
        klist_add_tail(&dev->p->knode_parent,
                   &parent->p->klist_children);

    if (dev->class) {
        mutex_lock(&dev->class->p->mutex);
        /* tie the class to the device */
        klist_add_tail(&dev->knode_class,
                   &dev->class->p->klist_devices);

        /* notify any interfaces that the device is here */
        list_for_each_entry(class_intf,
                    &dev->class->p->interfaces, node)
            if (class_intf->add_dev)
                class_intf->add_dev(dev, class_intf);
        mutex_unlock(&dev->class->p->mutex);
    }
done:
    put_device(dev);
    return error;
 DPMError:
    bus_remove_device(dev);
 BusError:
    device_remove_attrs(dev);
 AttrsError:
    device_remove_class_symlinks(dev);
 SymlinkError:
    if (MAJOR(dev->devt))
        devtmpfs_delete_node(dev);
    if (MAJOR(dev->devt))
        device_remove_sys_dev_entry(dev);
 devtattrError:
    if (MAJOR(dev->devt))
        device_remove_file(dev, &devt_attr);
 ueventattrError:
    device_remove_file(dev, &uevent_attr);
 attrError:
    kobject_uevent(&dev->kobj, KOBJ_REMOVE);
    kobject_del(&dev->kobj);
 Error:
    cleanup_device_parent(dev);
    if (parent)
        put_device(parent);
name_error:
    kfree(dev->p);
    dev->p = NULL;
    goto done;
}

int device_register(struct device *dev)
{
    device_initialize(dev);
    return device_add(dev);
}

struct device *get_device(struct device *dev)
{
    return dev ? kobj_to_dev(kobject_get(&dev->kobj)) : NULL;
}

void put_device(struct device *dev)
{
    /* might_sleep(); */
    if (dev)
        kobject_put(&dev->kobj);
}

void device_del(struct device *dev)
{
    struct device *parent = dev->parent;
    struct class_interface *class_intf;

    /* Notify clients of device removal.  This call must come
     * before dpm_sysfs_remove().
     */
    if (dev->bus)
        blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
                         BUS_NOTIFY_DEL_DEVICE, dev);
    device_pm_remove(dev);
    dpm_sysfs_remove(dev);
    if (parent)
        klist_del(&dev->p->knode_parent);
    if (MAJOR(dev->devt)) {
        devtmpfs_delete_node(dev);
        device_remove_sys_dev_entry(dev);
        device_remove_file(dev, &devt_attr);
    }
    if (dev->class) {
        device_remove_class_symlinks(dev);

        mutex_lock(&dev->class->p->mutex);
        /* notify any interfaces that the device is now gone */
        list_for_each_entry(class_intf,
                    &dev->class->p->interfaces, node)
            if (class_intf->remove_dev)
                class_intf->remove_dev(dev, class_intf);
        /* remove the device from the class list */
        klist_del(&dev->knode_class);
        mutex_unlock(&dev->class->p->mutex);
    }
    device_remove_file(dev, &uevent_attr);
    device_remove_attrs(dev);
    bus_remove_device(dev);
    driver_deferred_probe_del(dev);

    /* Notify the platform of the removal, in case they
     * need to do anything...
     */
    if (platform_notify_remove)
        platform_notify_remove(dev);
    kobject_uevent(&dev->kobj, KOBJ_REMOVE);
    cleanup_device_parent(dev);
    kobject_del(&dev->kobj);
    put_device(parent);
}

void device_unregister(struct device *dev)
{
    pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
    device_del(dev);
    put_device(dev);
}

static struct device *next_device(struct klist_iter *i)
{
    struct klist_node *n = klist_next(i);
    struct device *dev = NULL;
    struct device_private *p;

    if (n) {
        p = to_device_private_parent(n);
        dev = p->device;
    }
    return dev;
}

const char *device_get_devnode(struct device *dev,
                   umode_t *mode, const char **tmp)
{
    char *s;

    *tmp = NULL;

    /* the device type may provide a specific name */
    if (dev->type && dev->type->devnode)
        *tmp = dev->type->devnode(dev, mode);
    if (*tmp)
        return *tmp;

    /* the class may provide a specific name */
    if (dev->class && dev->class->devnode)
        *tmp = dev->class->devnode(dev, mode);
    if (*tmp)
        return *tmp;

    /* return name without allocation, tmp == NULL */
    if (strchr(dev_name(dev), '!') == NULL)
        return dev_name(dev);

    /* replace '!' in the name with '/' */
    *tmp = kstrdup(dev_name(dev), GFP_KERNEL);
    if (!*tmp)
        return NULL;
    while ((s = strchr(*tmp, '!')))
        s[0] = '/';
    return *tmp;
}

int device_for_each_child(struct device *parent, void *data,
              int (*fn)(struct device *dev, void *data))
{
    struct klist_iter i;
    struct device *child;
    int error = 0;

    if (!parent->p)
        return 0;

    klist_iter_init(&parent->p->klist_children, &i);
    while ((child = next_device(&i)) && !error)
        error = fn(child, data);
    klist_iter_exit(&i);
    return error;
}

struct device *device_find_child(struct device *parent, void *data,
                 int (*match)(struct device *dev, void *data))
{
    struct klist_iter i;
    struct device *child;

    if (!parent)
        return NULL;

    klist_iter_init(&parent->p->klist_children, &i);
    while ((child = next_device(&i)))
        if (match(child, data) && get_device(child))
            break;
    klist_iter_exit(&i);
    return child;
}

int __init devices_init(void)
{
    devices_kset = kset_create_and_add("devices", &device_uevent_ops, NULL);
    if (!devices_kset)
        return -ENOMEM;
    dev_kobj = kobject_create_and_add("dev", NULL);
    if (!dev_kobj)
        goto dev_kobj_err;
    sysfs_dev_block_kobj = kobject_create_and_add("block", dev_kobj);
    if (!sysfs_dev_block_kobj)
        goto block_kobj_err;
    sysfs_dev_char_kobj = kobject_create_and_add("char", dev_kobj);
    if (!sysfs_dev_char_kobj)
        goto char_kobj_err;

    return 0;

 char_kobj_err:
    kobject_put(sysfs_dev_block_kobj);
 block_kobj_err:
    kobject_put(dev_kobj);
 dev_kobj_err:
    kset_unregister(devices_kset);
    return -ENOMEM;
}

EXPORT_SYMBOL_GPL(device_for_each_child);
EXPORT_SYMBOL_GPL(device_find_child);

EXPORT_SYMBOL_GPL(device_initialize);
EXPORT_SYMBOL_GPL(device_add);
EXPORT_SYMBOL_GPL(device_register);

EXPORT_SYMBOL_GPL(device_del);
EXPORT_SYMBOL_GPL(device_unregister);
EXPORT_SYMBOL_GPL(get_device);
EXPORT_SYMBOL_GPL(put_device);

EXPORT_SYMBOL_GPL(device_create_file);
EXPORT_SYMBOL_GPL(device_remove_file);

struct root_device {
    struct device dev;
    struct module *owner;
};

inline struct root_device *to_root_device(struct device *d)
{
    return container_of(d, struct root_device, dev);
}

static void root_device_release(struct device *dev)
{
    kfree(to_root_device(dev));
}

struct device *__root_device_register(const char *name, struct module *owner)
{
    struct root_device *root;
    int err = -ENOMEM;

    root = kzalloc(sizeof(struct root_device), GFP_KERNEL);
    if (!root)
        return ERR_PTR(err);

    err = dev_set_name(&root->dev, "%s", name);
    if (err) {
        kfree(root);
        return ERR_PTR(err);
    }

    root->dev.release = root_device_release;

    err = device_register(&root->dev);
    if (err) {
        put_device(&root->dev);
        return ERR_PTR(err);
    }

#ifdef CONFIG_MODULES   /* gotta find a "cleaner" way to do this */
    if (owner) {
        struct module_kobject *mk = &owner->mkobj;

        err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");
        if (err) {
            device_unregister(&root->dev);
            return ERR_PTR(err);
        }
        root->owner = owner;
    }
#endif

    return &root->dev;
}
EXPORT_SYMBOL_GPL(__root_device_register);

void root_device_unregister(struct device *dev)
{
    struct root_device *root = to_root_device(dev);

    if (root->owner)
        sysfs_remove_link(&root->dev.kobj, "module");

    device_unregister(dev);
}
EXPORT_SYMBOL_GPL(root_device_unregister);


static void device_create_release(struct device *dev)
{
    pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
    kfree(dev);
}

struct device *device_create_vargs(struct class *class, struct device *parent,
                   dev_t devt, void *drvdata, const char *fmt,
                   va_list args)
{
    struct device *dev = NULL;
    int retval = -ENODEV;

    if (class == NULL || IS_ERR(class))
        goto error;

    dev = kzalloc(sizeof(*dev), GFP_KERNEL);
    if (!dev) {
        retval = -ENOMEM;
        goto error;
    }

    dev->devt = devt;
    dev->class = class;
    dev->parent = parent;
    dev->release = device_create_release;
    dev_set_drvdata(dev, drvdata);

    retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
    if (retval)
        goto error;

    retval = device_register(dev);
    if (retval)
        goto error;

    return dev;

error:
    put_device(dev);
    return ERR_PTR(retval);
}
EXPORT_SYMBOL_GPL(device_create_vargs);

struct device *device_create(struct class *class, struct device *parent,
                 dev_t devt, void *drvdata, const char *fmt, ...)
{
    va_list vargs;
    struct device *dev;

    va_start(vargs, fmt);
    dev = device_create_vargs(class, parent, devt, drvdata, fmt, vargs);
    va_end(vargs);
    return dev;
}
EXPORT_SYMBOL_GPL(device_create);

static int __match_devt(struct device *dev, void *data)
{
    dev_t *devt = data;

    return dev->devt == *devt;
}

void device_destroy(struct class *class, dev_t devt)
{
    struct device *dev;

    dev = class_find_device(class, NULL, &devt, __match_devt);
    if (dev) {
        put_device(dev);
        device_unregister(dev);
    }
}
EXPORT_SYMBOL_GPL(device_destroy);

int device_rename(struct device *dev, const char *new_name)
{
    char *old_class_name = NULL;
    char *new_class_name = NULL;
    char *old_device_name = NULL;
    int error;

    dev = get_device(dev);
    if (!dev)
        return -EINVAL;

    pr_debug("device: '%s': %s: renaming to '%s'\n", dev_name(dev),
         __func__, new_name);

    old_device_name = kstrdup(dev_name(dev), GFP_KERNEL);
    if (!old_device_name) {
        error = -ENOMEM;
        goto out;
    }

    if (dev->class) {
        error = sysfs_rename_link(&dev->class->p->subsys.kobj,
            &dev->kobj, old_device_name, new_name);
        if (error)
            goto out;
    }

    error = kobject_rename(&dev->kobj, new_name);
    if (error)
        goto out;

out:
    put_device(dev);

    kfree(new_class_name);
    kfree(old_class_name);
    kfree(old_device_name);

    return error;
}
EXPORT_SYMBOL_GPL(device_rename);

static int device_move_class_links(struct device *dev,
                   struct device *old_parent,
                   struct device *new_parent)
{
    int error = 0;

    if (old_parent)
        sysfs_remove_link(&dev->kobj, "device");
    if (new_parent)
        error = sysfs_create_link(&dev->kobj, &new_parent->kobj,
                      "device");
    return error;
}

int device_move(struct device *dev, struct device *new_parent,
        enum dpm_order dpm_order)
{
    int error;
    struct device *old_parent;
    struct kobject *new_parent_kobj;

    dev = get_device(dev);
    if (!dev)
        return -EINVAL;

    device_pm_lock();
    new_parent = get_device(new_parent);
    new_parent_kobj = get_device_parent(dev, new_parent);

    pr_debug("device: '%s': %s: moving to '%s'\n", dev_name(dev),
         __func__, new_parent ? dev_name(new_parent) : "<NULL>");
    error = kobject_move(&dev->kobj, new_parent_kobj);
    if (error) {
        cleanup_glue_dir(dev, new_parent_kobj);
        put_device(new_parent);
        goto out;
    }
    old_parent = dev->parent;
    dev->parent = new_parent;
    if (old_parent)
        klist_remove(&dev->p->knode_parent);
    if (new_parent) {
        klist_add_tail(&dev->p->knode_parent,
                   &new_parent->p->klist_children);
        set_dev_node(dev, dev_to_node(new_parent));
    }

    if (dev->class) {
        error = device_move_class_links(dev, old_parent, new_parent);
        if (error) {
            /* We ignore errors on cleanup since we're hosed anyway... */
            device_move_class_links(dev, new_parent, old_parent);
            if (!kobject_move(&dev->kobj, &old_parent->kobj)) {
                if (new_parent)
                    klist_remove(&dev->p->knode_parent);
                dev->parent = old_parent;
                if (old_parent) {
                    klist_add_tail(&dev->p->knode_parent,
                               &old_parent->p->klist_children);
                    set_dev_node(dev, dev_to_node(old_parent));
                }
            }
            cleanup_glue_dir(dev, new_parent_kobj);
            put_device(new_parent);
            goto out;
        }
    }
    switch (dpm_order) {
    case DPM_ORDER_NONE:
        break;
    case DPM_ORDER_DEV_AFTER_PARENT:
        device_pm_move_after(dev, new_parent);
        break;
    case DPM_ORDER_PARENT_BEFORE_DEV:
        device_pm_move_before(new_parent, dev);
        break;
    case DPM_ORDER_DEV_LAST:
        device_pm_move_last(dev);
        break;
    }

    put_device(old_parent);
out:
    device_pm_unlock();
    put_device(dev);
    return error;
}
EXPORT_SYMBOL_GPL(device_move);

void device_shutdown(void)
{
    struct device *dev;

    spin_lock(&devices_kset->list_lock);
    /*
     * Walk the devices list backward, shutting down each in turn.
     * Beware that device unplug events may also start pulling
     * devices offline, even as the system is shutting down.
     */
    while (!list_empty(&devices_kset->list)) {
        dev = list_entry(devices_kset->list.prev, struct device,
                kobj.entry);

        /*
         * hold reference count of device's parent to
         * prevent it from being freed because parent's
         * lock is to be held
         */
        get_device(dev->parent);
        get_device(dev);
        /*
         * Make sure the device is off the kset list, in the
         * event that dev->*->shutdown() doesn't remove it.
         */
        list_del_init(&dev->kobj.entry);
        spin_unlock(&devices_kset->list_lock);

        /* hold lock to avoid race with probe/release */
        if (dev->parent)
            device_lock(dev->parent);
        device_lock(dev);

        /* Don't allow any more runtime suspends */
        pm_runtime_get_noresume(dev);
        pm_runtime_barrier(dev);

        if (dev->bus && dev->bus->shutdown) {
            dev_dbg(dev, "shutdown\n");
            dev->bus->shutdown(dev);
        } else if (dev->driver && dev->driver->shutdown) {
            dev_dbg(dev, "shutdown\n");
            dev->driver->shutdown(dev);
        }

        device_unlock(dev);
        if (dev->parent)
            device_unlock(dev->parent);

        put_device(dev);
        put_device(dev->parent);

        spin_lock(&devices_kset->list_lock);
    }
    spin_unlock(&devices_kset->list_lock);
    async_synchronize_full();
}

/*
 * Device logging functions
 */

#ifdef CONFIG_PRINTK
static int
create_syslog_header(const struct device *dev, char *hdr, size_t hdrlen)
{
    const char *subsys;
    size_t pos = 0;

    if (dev->class)
        subsys = dev->class->name;
    else if (dev->bus)
        subsys = dev->bus->name;
    else
        return 0;

    pos += snprintf(hdr + pos, hdrlen - pos, "SUBSYSTEM=%s", subsys);

    /*
     * Add device identifier DEVICE=:
     *   b12:8         block dev_t
     *   c127:3        char dev_t
     *   n8            netdev ifindex
     *   +sound:card0  subsystem:devname
     */
    if (MAJOR(dev->devt)) {
        char c;

        if (strcmp(subsys, "block") == 0)
            c = 'b';
        else
            c = 'c';
        pos++;
        pos += snprintf(hdr + pos, hdrlen - pos,
                "DEVICE=%c%u:%u",
                c, MAJOR(dev->devt), MINOR(dev->devt));
    } else if (strcmp(subsys, "net") == 0) {
        struct net_device *net = to_net_dev(dev);

        pos++;
        pos += snprintf(hdr + pos, hdrlen - pos,
                "DEVICE=n%u", net->ifindex);
    } else {
        pos++;
        pos += snprintf(hdr + pos, hdrlen - pos,
                "DEVICE=+%s:%s", subsys, dev_name(dev));
    }

    return pos;
}
EXPORT_SYMBOL(create_syslog_header);

int dev_vprintk_emit(int level, const struct device *dev,
             const char *fmt, va_list args)
{
    char hdr[128];
    size_t hdrlen;

    hdrlen = create_syslog_header(dev, hdr, sizeof(hdr));

    return vprintk_emit(0, level, hdrlen ? hdr : NULL, hdrlen, fmt, args);
}
EXPORT_SYMBOL(dev_vprintk_emit);

int dev_printk_emit(int level, const struct device *dev, const char *fmt, ...)
{
    va_list args;
    int r;

    va_start(args, fmt);

    r = dev_vprintk_emit(level, dev, fmt, args);

    va_end(args);

    return r;
}
EXPORT_SYMBOL(dev_printk_emit);

static int __dev_printk(const char *level, const struct device *dev,
            struct va_format *vaf)
{
    if (!dev)
        return printk("%s(NULL device *): %pV", level, vaf);

    return dev_printk_emit(level[1] - '0', dev,
                   "%s %s: %pV",
                   dev_driver_string(dev), dev_name(dev), vaf);
}

int dev_printk(const char *level, const struct device *dev,
           const char *fmt, ...)
{
    struct va_format vaf;
    va_list args;
    int r;

    va_start(args, fmt);

    vaf.fmt = fmt;
    vaf.va = &args;

    r = __dev_printk(level, dev, &vaf);

    va_end(args);

    return r;
}
EXPORT_SYMBOL(dev_printk);

#define define_dev_printk_level(func, kern_level)       \
int func(const struct device *dev, const char *fmt, ...)    \
{                               \
    struct va_format vaf;                   \
    va_list args;                       \
    int r;                          \
                                \
    va_start(args, fmt);                    \
                                \
    vaf.fmt = fmt;                      \
    vaf.va = &args;                     \
                                \
    r = __dev_printk(kern_level, dev, &vaf);        \
                                \
    va_end(args);                       \
                                \
    return r;                       \
}                               \
EXPORT_SYMBOL(func);

define_dev_printk_level(dev_emerg, KERN_EMERG);
define_dev_printk_level(dev_alert, KERN_ALERT);
define_dev_printk_level(dev_crit, KERN_CRIT);
define_dev_printk_level(dev_err, KERN_ERR);
define_dev_printk_level(dev_warn, KERN_WARNING);
define_dev_printk_level(dev_notice, KERN_NOTICE);
define_dev_printk_level(_dev_info, KERN_INFO);

#endif