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class.c

/*
 * class.c - basic device class management
 *
 * Copyright (c) 2002-3 Patrick Mochel
 * Copyright (c) 2002-3 Open Source Development Labs
 * Copyright (c) 2003-2004 Greg Kroah-Hartman
 * Copyright (c) 2003-2004 IBM Corp.
 *
 * This file is released under the GPLv2
 *
 */

#include <linux/device.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/kdev_t.h>
#include <linux/err.h>
#include <linux/slab.h>
#include "base.h"

#define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
#define to_class(obj) container_of(obj, struct class, subsys.kobj)

static ssize_t
class_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
{
      struct class_attribute * class_attr = to_class_attr(attr);
      struct class * dc = to_class(kobj);
      ssize_t ret = -EIO;

      if (class_attr->show)
            ret = class_attr->show(dc, buf);
      return ret;
}

static ssize_t
class_attr_store(struct kobject * kobj, struct attribute * attr,
             const char * buf, size_t count)
{
      struct class_attribute * class_attr = to_class_attr(attr);
      struct class * dc = to_class(kobj);
      ssize_t ret = -EIO;

      if (class_attr->store)
            ret = class_attr->store(dc, buf, count);
      return ret;
}

static void class_release(struct kobject * kobj)
{
      struct class *class = to_class(kobj);

      pr_debug("class '%s': release.\n", class->name);

      if (class->class_release)
            class->class_release(class);
      else
            pr_debug("class '%s' does not have a release() function, "
                   "be careful\n", class->name);
}

static struct sysfs_ops class_sysfs_ops = {
      .show = class_attr_show,
      .store      = class_attr_store,
};

static struct kobj_type class_ktype = {
      .sysfs_ops  = &class_sysfs_ops,
      .release    = class_release,
};

/* Hotplug events for classes go to the class_obj subsys */
static decl_subsys(class, &class_ktype, NULL);


int class_create_file(struct class * cls, const struct class_attribute * attr)
{
      int error;
      if (cls) {
            error = sysfs_create_file(&cls->subsys.kobj, &attr->attr);
      } else
            error = -EINVAL;
      return error;
}

void class_remove_file(struct class * cls, const struct class_attribute * attr)
{
      if (cls)
            sysfs_remove_file(&cls->subsys.kobj, &attr->attr);
}

static struct class *class_get(struct class *cls)
{
      if (cls)
            return container_of(kset_get(&cls->subsys), struct class, subsys);
      return NULL;
}

static void class_put(struct class * cls)
{
      if (cls)
            kset_put(&cls->subsys);
}


static int add_class_attrs(struct class * cls)
{
      int i;
      int error = 0;

      if (cls->class_attrs) {
            for (i = 0; attr_name(cls->class_attrs[i]); i++) {
                  error = class_create_file(cls,&cls->class_attrs[i]);
                  if (error)
                        goto Err;
            }
      }
 Done:
      return error;
 Err:
      while (--i >= 0)
            class_remove_file(cls,&cls->class_attrs[i]);
      goto Done;
}

static void remove_class_attrs(struct class * cls)
{
      int i;

      if (cls->class_attrs) {
            for (i = 0; attr_name(cls->class_attrs[i]); i++)
                  class_remove_file(cls,&cls->class_attrs[i]);
      }
}

int class_register(struct class * cls)
{
      int error;

      pr_debug("device class '%s': registering\n", cls->name);

      INIT_LIST_HEAD(&cls->children);
      INIT_LIST_HEAD(&cls->devices);
      INIT_LIST_HEAD(&cls->interfaces);
      kset_init(&cls->class_dirs);
      init_MUTEX(&cls->sem);
      error = kobject_set_name(&cls->subsys.kobj, "%s", cls->name);
      if (error)
            return error;

      cls->subsys.kobj.kset = &class_subsys;

      error = subsystem_register(&cls->subsys);
      if (!error) {
            error = add_class_attrs(class_get(cls));
            class_put(cls);
      }
      return error;
}

void class_unregister(struct class * cls)
{
      pr_debug("device class '%s': unregistering\n", cls->name);
      remove_class_attrs(cls);
      subsystem_unregister(&cls->subsys);
}

static void class_create_release(struct class *cls)
{
      pr_debug("%s called for %s\n", __FUNCTION__, cls->name);
      kfree(cls);
}

static void class_device_create_release(struct class_device *class_dev)
{
      pr_debug("%s called for %s\n", __FUNCTION__, class_dev->class_id);
      kfree(class_dev);
}

/* needed to allow these devices to have parent class devices */
static int class_device_create_uevent(struct class_device *class_dev,
                              struct kobj_uevent_env *env)
{
      pr_debug("%s called for %s\n", __FUNCTION__, class_dev->class_id);
      return 0;
}

/**
 * class_create - create a struct class structure
 * @owner: pointer to the module that is to "own" this struct class
 * @name: pointer to a string for the name of this class.
 *
 * This is used to create a struct class pointer that can then be used
 * in calls to class_device_create().
 *
 * Note, the pointer created here is to be destroyed when finished by
 * making a call to class_destroy().
 */
struct class *class_create(struct module *owner, const char *name)
{
      struct class *cls;
      int retval;

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

      cls->name = name;
      cls->owner = owner;
      cls->class_release = class_create_release;
      cls->release = class_device_create_release;

      retval = class_register(cls);
      if (retval)
            goto error;

      return cls;

error:
      kfree(cls);
      return ERR_PTR(retval);
}

/**
 * class_destroy - destroys a struct class structure
 * @cls: pointer to the struct class that is to be destroyed
 *
 * Note, the pointer to be destroyed must have been created with a call
 * to class_create().
 */
void class_destroy(struct class *cls)
{
      if ((cls == NULL) || (IS_ERR(cls)))
            return;

      class_unregister(cls);
}

/* Class Device Stuff */

int class_device_create_file(struct class_device * class_dev,
                       const struct class_device_attribute * attr)
{
      int error = -EINVAL;
      if (class_dev)
            error = sysfs_create_file(&class_dev->kobj, &attr->attr);
      return error;
}

void class_device_remove_file(struct class_device * class_dev,
                        const struct class_device_attribute * attr)
{
      if (class_dev)
            sysfs_remove_file(&class_dev->kobj, &attr->attr);
}

int class_device_create_bin_file(struct class_device *class_dev,
                         struct bin_attribute *attr)
{
      int error = -EINVAL;
      if (class_dev)
            error = sysfs_create_bin_file(&class_dev->kobj, attr);
      return error;
}

void class_device_remove_bin_file(struct class_device *class_dev,
                          struct bin_attribute *attr)
{
      if (class_dev)
            sysfs_remove_bin_file(&class_dev->kobj, attr);
}

static ssize_t
class_device_attr_show(struct kobject * kobj, struct attribute * attr,
                   char * buf)
{
      struct class_device_attribute * class_dev_attr = to_class_dev_attr(attr);
      struct class_device * cd = to_class_dev(kobj);
      ssize_t ret = 0;

      if (class_dev_attr->show)
            ret = class_dev_attr->show(cd, buf);
      return ret;
}

static ssize_t
class_device_attr_store(struct kobject * kobj, struct attribute * attr,
                  const char * buf, size_t count)
{
      struct class_device_attribute * class_dev_attr = to_class_dev_attr(attr);
      struct class_device * cd = to_class_dev(kobj);
      ssize_t ret = 0;

      if (class_dev_attr->store)
            ret = class_dev_attr->store(cd, buf, count);
      return ret;
}

static struct sysfs_ops class_dev_sysfs_ops = {
      .show = class_device_attr_show,
      .store      = class_device_attr_store,
};

static void class_dev_release(struct kobject * kobj)
{
      struct class_device *cd = to_class_dev(kobj);
      struct class * cls = cd->class;

      pr_debug("device class '%s': release.\n", cd->class_id);

      if (cd->release)
            cd->release(cd);
      else if (cls->release)
            cls->release(cd);
      else {
            printk(KERN_ERR "Class Device '%s' does not have a release() function, "
                  "it is broken and must be fixed.\n",
                  cd->class_id);
            WARN_ON(1);
      }
}

static struct kobj_type class_device_ktype = {
      .sysfs_ops  = &class_dev_sysfs_ops,
      .release    = class_dev_release,
};

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

      if (ktype == &class_device_ktype) {
            struct class_device *class_dev = to_class_dev(kobj);
            if (class_dev->class)
                  return 1;
      }
      return 0;
}

static const char *class_uevent_name(struct kset *kset, struct kobject *kobj)
{
      struct class_device *class_dev = to_class_dev(kobj);

      return class_dev->class->name;
}

#ifdef CONFIG_SYSFS_DEPRECATED
char *make_class_name(const char *name, struct kobject *kobj)
{
      char *class_name;
      int size;

      size = strlen(name) + strlen(kobject_name(kobj)) + 2;

      class_name = kmalloc(size, GFP_KERNEL);
      if (!class_name)
            return NULL;

      strcpy(class_name, name);
      strcat(class_name, ":");
      strcat(class_name, kobject_name(kobj));
      return class_name;
}

static int make_deprecated_class_device_links(struct class_device *class_dev)
{
      char *class_name;
      int error;

      if (!class_dev->dev)
            return 0;

      class_name = make_class_name(class_dev->class->name, &class_dev->kobj);
      if (class_name)
            error = sysfs_create_link(&class_dev->dev->kobj,
                                &class_dev->kobj, class_name);
      else
            error = -ENOMEM;
      kfree(class_name);
      return error;
}

static void remove_deprecated_class_device_links(struct class_device *class_dev)
{
      char *class_name;

      if (!class_dev->dev)
            return;

      class_name = make_class_name(class_dev->class->name, &class_dev->kobj);
      if (class_name)
            sysfs_remove_link(&class_dev->dev->kobj, class_name);
      kfree(class_name);
}
#else
static inline int make_deprecated_class_device_links(struct class_device *cd)
{ return 0; }
static void remove_deprecated_class_device_links(struct class_device *cd)
{ }
#endif

static int class_uevent(struct kset *kset, struct kobject *kobj,
                  struct kobj_uevent_env *env)
{
      struct class_device *class_dev = to_class_dev(kobj);
      struct device *dev = class_dev->dev;
      int retval = 0;

      pr_debug("%s - name = %s\n", __FUNCTION__, class_dev->class_id);

      if (MAJOR(class_dev->devt)) {
            add_uevent_var(env, "MAJOR=%u", MAJOR(class_dev->devt));

            add_uevent_var(env, "MINOR=%u", MINOR(class_dev->devt));
      }

      if (dev) {
            const char *path = kobject_get_path(&dev->kobj, GFP_KERNEL);
            if (path) {
                  add_uevent_var(env, "PHYSDEVPATH=%s", path);
                  kfree(path);
            }

            if (dev->bus)
                  add_uevent_var(env, "PHYSDEVBUS=%s", dev->bus->name);

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

      if (class_dev->uevent) {
            /* have the class device specific function add its stuff */
            retval = class_dev->uevent(class_dev, env);
            if (retval)
                  pr_debug("class_dev->uevent() returned %d\n", retval);
      } else if (class_dev->class->uevent) {
            /* have the class specific function add its stuff */
            retval = class_dev->class->uevent(class_dev, env);
            if (retval)
                  pr_debug("class->uevent() returned %d\n", retval);
      }

      return retval;
}

static struct kset_uevent_ops class_uevent_ops = {
      .filter =   class_uevent_filter,
      .name =           class_uevent_name,
      .uevent =   class_uevent,
};

static decl_subsys(class_obj, &class_device_ktype, &class_uevent_ops);


static int class_device_add_attrs(struct class_device * cd)
{
      int i;
      int error = 0;
      struct class * cls = cd->class;

      if (cls->class_dev_attrs) {
            for (i = 0; attr_name(cls->class_dev_attrs[i]); i++) {
                  error = class_device_create_file(cd,
                                           &cls->class_dev_attrs[i]);
                  if (error)
                        goto Err;
            }
      }
 Done:
      return error;
 Err:
      while (--i >= 0)
            class_device_remove_file(cd,&cls->class_dev_attrs[i]);
      goto Done;
}

static void class_device_remove_attrs(struct class_device * cd)
{
      int i;
      struct class * cls = cd->class;

      if (cls->class_dev_attrs) {
            for (i = 0; attr_name(cls->class_dev_attrs[i]); i++)
                  class_device_remove_file(cd,&cls->class_dev_attrs[i]);
      }
}

static int class_device_add_groups(struct class_device * cd)
{
      int i;
      int error = 0;

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

static void class_device_remove_groups(struct class_device * cd)
{
      int i;
      if (cd->groups) {
            for (i = 0; cd->groups[i]; i++) {
                  sysfs_remove_group(&cd->kobj, cd->groups[i]);
            }
      }
}

static ssize_t show_dev(struct class_device *class_dev, char *buf)
{
      return print_dev_t(buf, class_dev->devt);
}

static struct class_device_attribute class_devt_attr =
      __ATTR(dev, S_IRUGO, show_dev, NULL);

static ssize_t store_uevent(struct class_device *class_dev,
                      const char *buf, size_t count)
{
      kobject_uevent(&class_dev->kobj, KOBJ_ADD);
      return count;
}

static struct class_device_attribute class_uevent_attr =
      __ATTR(uevent, S_IWUSR, NULL, store_uevent);

void class_device_initialize(struct class_device *class_dev)
{
      kobj_set_kset_s(class_dev, class_obj_subsys);
      kobject_init(&class_dev->kobj);
      INIT_LIST_HEAD(&class_dev->node);
}

int class_device_add(struct class_device *class_dev)
{
      struct class *parent_class = NULL;
      struct class_device *parent_class_dev = NULL;
      struct class_interface *class_intf;
      int error = -EINVAL;

      class_dev = class_device_get(class_dev);
      if (!class_dev)
            return -EINVAL;

      if (!strlen(class_dev->class_id))
            goto out1;

      parent_class = class_get(class_dev->class);
      if (!parent_class)
            goto out1;

      parent_class_dev = class_device_get(class_dev->parent);

      pr_debug("CLASS: registering class device: ID = '%s'\n",
             class_dev->class_id);

      /* first, register with generic layer. */
      error = kobject_set_name(&class_dev->kobj, "%s", class_dev->class_id);
      if (error)
            goto out2;

      if (parent_class_dev)
            class_dev->kobj.parent = &parent_class_dev->kobj;
      else
            class_dev->kobj.parent = &parent_class->subsys.kobj;

      error = kobject_add(&class_dev->kobj);
      if (error)
            goto out2;

      /* add the needed attributes to this device */
      error = sysfs_create_link(&class_dev->kobj,
                          &parent_class->subsys.kobj, "subsystem");
      if (error)
            goto out3;

      error = class_device_create_file(class_dev, &class_uevent_attr);
      if (error)
            goto out3;

      if (MAJOR(class_dev->devt)) {
            error = class_device_create_file(class_dev, &class_devt_attr);
            if (error)
                  goto out4;
      }

      error = class_device_add_attrs(class_dev);
      if (error)
            goto out5;

      if (class_dev->dev) {
            error = sysfs_create_link(&class_dev->kobj,
                                &class_dev->dev->kobj, "device");
            if (error)
                  goto out6;
      }

      error = class_device_add_groups(class_dev);
      if (error)
            goto out7;

      error = make_deprecated_class_device_links(class_dev);
      if (error)
            goto out8;

      kobject_uevent(&class_dev->kobj, KOBJ_ADD);

      /* notify any interfaces this device is now here */
      down(&parent_class->sem);
      list_add_tail(&class_dev->node, &parent_class->children);
      list_for_each_entry(class_intf, &parent_class->interfaces, node) {
            if (class_intf->add)
                  class_intf->add(class_dev, class_intf);
      }
      up(&parent_class->sem);

      goto out1;

 out8:
      class_device_remove_groups(class_dev);
 out7:
      if (class_dev->dev)
            sysfs_remove_link(&class_dev->kobj, "device");
 out6:
      class_device_remove_attrs(class_dev);
 out5:
      if (MAJOR(class_dev->devt))
            class_device_remove_file(class_dev, &class_devt_attr);
 out4:
      class_device_remove_file(class_dev, &class_uevent_attr);
 out3:
      kobject_del(&class_dev->kobj);
 out2:
      if(parent_class_dev)
            class_device_put(parent_class_dev);
      class_put(parent_class);
 out1:
      class_device_put(class_dev);
      return error;
}

int class_device_register(struct class_device *class_dev)
{
      class_device_initialize(class_dev);
      return class_device_add(class_dev);
}

/**
 * class_device_create - creates a class device and registers it with sysfs
 * @cls: pointer to the struct class that this device should be registered to.
 * @parent: pointer to the parent struct class_device of this new device, if any.
 * @devt: the dev_t for the char device to be added.
 * @device: a pointer to a struct device that is assiociated with this class device.
 * @fmt: string for the class device's name
 *
 * This function can be used by char device classes.  A struct
 * class_device will be created in sysfs, registered to the specified
 * class.
 * A "dev" file will be created, showing the dev_t for the device, if
 * the dev_t is not 0,0.
 * If a pointer to a parent struct class_device is passed in, the newly
 * created struct class_device will be a child of that device in sysfs.
 * The pointer to the struct class_device will be returned from the
 * call.  Any further sysfs files that might be required can be created
 * using this pointer.
 *
 * Note: the struct class passed to this function must have previously
 * been created with a call to class_create().
 */
struct class_device *class_device_create(struct class *cls,
                               struct class_device *parent,
                               dev_t devt,
                               struct device *device,
                               const char *fmt, ...)
{
      va_list args;
      struct class_device *class_dev = NULL;
      int retval = -ENODEV;

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

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

      class_dev->devt = devt;
      class_dev->dev = device;
      class_dev->class = cls;
      class_dev->parent = parent;
      class_dev->release = class_device_create_release;
      class_dev->uevent = class_device_create_uevent;

      va_start(args, fmt);
      vsnprintf(class_dev->class_id, BUS_ID_SIZE, fmt, args);
      va_end(args);
      retval = class_device_register(class_dev);
      if (retval)
            goto error;

      return class_dev;

error:
      kfree(class_dev);
      return ERR_PTR(retval);
}

void class_device_del(struct class_device *class_dev)
{
      struct class *parent_class = class_dev->class;
      struct class_device *parent_device = class_dev->parent;
      struct class_interface *class_intf;

      if (parent_class) {
            down(&parent_class->sem);
            list_del_init(&class_dev->node);
            list_for_each_entry(class_intf, &parent_class->interfaces, node)
                  if (class_intf->remove)
                        class_intf->remove(class_dev, class_intf);
            up(&parent_class->sem);
      }

      if (class_dev->dev) {
            remove_deprecated_class_device_links(class_dev);
            sysfs_remove_link(&class_dev->kobj, "device");
      }
      sysfs_remove_link(&class_dev->kobj, "subsystem");
      class_device_remove_file(class_dev, &class_uevent_attr);
      if (MAJOR(class_dev->devt))
            class_device_remove_file(class_dev, &class_devt_attr);
      class_device_remove_attrs(class_dev);
      class_device_remove_groups(class_dev);

      kobject_uevent(&class_dev->kobj, KOBJ_REMOVE);
      kobject_del(&class_dev->kobj);

      class_device_put(parent_device);
      class_put(parent_class);
}

void class_device_unregister(struct class_device *class_dev)
{
      pr_debug("CLASS: Unregistering class device. ID = '%s'\n",
             class_dev->class_id);
      class_device_del(class_dev);
      class_device_put(class_dev);
}

/**
 * class_device_destroy - removes a class device that was created with class_device_create()
 * @cls: the pointer to the struct class that this device was registered * with.
 * @devt: the dev_t of the device that was previously registered.
 *
 * This call unregisters and cleans up a class device that was created with a
 * call to class_device_create()
 */
void class_device_destroy(struct class *cls, dev_t devt)
{
      struct class_device *class_dev = NULL;
      struct class_device *class_dev_tmp;

      down(&cls->sem);
      list_for_each_entry(class_dev_tmp, &cls->children, node) {
            if (class_dev_tmp->devt == devt) {
                  class_dev = class_dev_tmp;
                  break;
            }
      }
      up(&cls->sem);

      if (class_dev)
            class_device_unregister(class_dev);
}

struct class_device * class_device_get(struct class_device *class_dev)
{
      if (class_dev)
            return to_class_dev(kobject_get(&class_dev->kobj));
      return NULL;
}

void class_device_put(struct class_device *class_dev)
{
      if (class_dev)
            kobject_put(&class_dev->kobj);
}


int class_interface_register(struct class_interface *class_intf)
{
      struct class *parent;
      struct class_device *class_dev;
      struct device *dev;

      if (!class_intf || !class_intf->class)
            return -ENODEV;

      parent = class_get(class_intf->class);
      if (!parent)
            return -EINVAL;

      down(&parent->sem);
      list_add_tail(&class_intf->node, &parent->interfaces);
      if (class_intf->add) {
            list_for_each_entry(class_dev, &parent->children, node)
                  class_intf->add(class_dev, class_intf);
      }
      if (class_intf->add_dev) {
            list_for_each_entry(dev, &parent->devices, node)
                  class_intf->add_dev(dev, class_intf);
      }
      up(&parent->sem);

      return 0;
}

void class_interface_unregister(struct class_interface *class_intf)
{
      struct class * parent = class_intf->class;
      struct class_device *class_dev;
      struct device *dev;

      if (!parent)
            return;

      down(&parent->sem);
      list_del_init(&class_intf->node);
      if (class_intf->remove) {
            list_for_each_entry(class_dev, &parent->children, node)
                  class_intf->remove(class_dev, class_intf);
      }
      if (class_intf->remove_dev) {
            list_for_each_entry(dev, &parent->devices, node)
                  class_intf->remove_dev(dev, class_intf);
      }
      up(&parent->sem);

      class_put(parent);
}

int __init classes_init(void)
{
      int retval;

      retval = subsystem_register(&class_subsys);
      if (retval)
            return retval;

      /* ick, this is ugly, the things we go through to keep from showing up
       * in sysfs... */
      kset_init(&class_obj_subsys);
      if (!class_obj_subsys.kobj.parent)
            class_obj_subsys.kobj.parent = &class_obj_subsys.kobj;
      return 0;
}

EXPORT_SYMBOL_GPL(class_create_file);
EXPORT_SYMBOL_GPL(class_remove_file);
EXPORT_SYMBOL_GPL(class_register);
EXPORT_SYMBOL_GPL(class_unregister);
EXPORT_SYMBOL_GPL(class_create);
EXPORT_SYMBOL_GPL(class_destroy);

EXPORT_SYMBOL_GPL(class_device_register);
EXPORT_SYMBOL_GPL(class_device_unregister);
EXPORT_SYMBOL_GPL(class_device_initialize);
EXPORT_SYMBOL_GPL(class_device_add);
EXPORT_SYMBOL_GPL(class_device_del);
EXPORT_SYMBOL_GPL(class_device_get);
EXPORT_SYMBOL_GPL(class_device_put);
EXPORT_SYMBOL_GPL(class_device_create);
EXPORT_SYMBOL_GPL(class_device_destroy);
EXPORT_SYMBOL_GPL(class_device_create_file);
EXPORT_SYMBOL_GPL(class_device_remove_file);
EXPORT_SYMBOL_GPL(class_device_create_bin_file);
EXPORT_SYMBOL_GPL(class_device_remove_bin_file);

EXPORT_SYMBOL_GPL(class_interface_register);
EXPORT_SYMBOL_GPL(class_interface_unregister);

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