// SPDX-License-Identifier: GPL-2.0

  /*
   * driver.c - centralized device driver management
   *
   * Copyright (c) 2002-3 Patrick Mochel
   * Copyright (c) 2002-3 Open Source Development Labs

   * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
   * Copyright (c) 2007 Novell Inc.

   */

  #include <linux/device/driver.h>

  #include <linux/device.h>
  #include <linux/module.h>
  #include <linux/errno.h>

  #include <linux/slab.h>

  #include <linux/string.h>

  #include <linux/sysfs.h>

  #include "base.h"

  static struct device *next_device(struct klist_iter *i)

  {

  	struct klist_node *n = klist_next(i);

  	struct device *dev = NULL;
  	struct device_private *dev_prv;
  
  	if (n) {
  		dev_prv = to_device_private_driver(n);
  		dev = dev_prv->device;
  	}
  	return dev;

  }

  /**

   * driver_for_each_device - Iterator for devices bound to a driver.
   * @drv: Driver we're iterating.
   * @start: Device to begin with
   * @data: Data to pass to the callback.
   * @fn: Function to call for each device.

   *

   * Iterate over the @drv's list of devices calling @fn for each one.

   */

  int driver_for_each_device(struct device_driver *drv, struct device *start,
  			   void *data, int (*fn)(struct device *, void *))

  {

  	struct klist_iter i;

  	struct device *dev;

  	int error = 0;

  	if (!drv)
  		return -EINVAL;

  	klist_iter_init_node(&drv->p->klist_devices, &i,
  			     start ? &start->p->knode_driver : NULL);

  	while (!error && (dev = next_device(&i)))

  		error = fn(dev, data);
  	klist_iter_exit(&i);

  	return error;
  }

  EXPORT_SYMBOL_GPL(driver_for_each_device);

  /**

   * driver_find_device - device iterator for locating a particular device.

   * @drv: The device's driver

   * @start: Device to begin with
   * @data: Data to pass to match function
   * @match: Callback function to check device
   *
   * This is similar to the driver_for_each_device() function above, but
   * it returns a reference to a device that is 'found' for later use, as
   * determined by the @match callback.
   *
   * The callback should return 0 if the device doesn't match and non-zero
   * if it does.  If the callback returns non-zero, this function will
   * return to the caller and not iterate over any more devices.
   */

  struct device *driver_find_device(struct device_driver *drv,

  				  struct device *start, const void *data,
  				  int (*match)(struct device *dev, const void *data))

  {
  	struct klist_iter i;
  	struct device *dev;

  	if (!drv || !drv->p)

  		return NULL;

  	klist_iter_init_node(&drv->p->klist_devices, &i,
  			     (start ? &start->p->knode_driver : NULL));

  	while ((dev = next_device(&i)))
  		if (match(dev, data) && get_device(dev))
  			break;
  	klist_iter_exit(&i);
  	return dev;
  }
  EXPORT_SYMBOL_GPL(driver_find_device);
  
  /**

   * driver_create_file - create sysfs file for driver.
   * @drv: driver.
   * @attr: driver attribute descriptor.

   */

  int driver_create_file(struct device_driver *drv,

  		       const struct driver_attribute *attr)

  {
  	int error;

  	if (drv)

  		error = sysfs_create_file(&drv->p->kobj, &attr->attr);

  	else

  		error = -EINVAL;
  	return error;
  }

  EXPORT_SYMBOL_GPL(driver_create_file);

  
  /**

   * driver_remove_file - remove sysfs file for driver.
   * @drv: driver.
   * @attr: driver attribute descriptor.

   */

  void driver_remove_file(struct device_driver *drv,

  			const struct driver_attribute *attr)

  {

  	if (drv)

  		sysfs_remove_file(&drv->p->kobj, &attr->attr);

  }

  EXPORT_SYMBOL_GPL(driver_remove_file);

  int driver_add_groups(struct device_driver *drv,
  		      const struct attribute_group **groups)

  {

  	return sysfs_create_groups(&drv->p->kobj, groups);

  }

  void driver_remove_groups(struct device_driver *drv,
  			  const struct attribute_group **groups)

  {

  	sysfs_remove_groups(&drv->p->kobj, groups);

  }

  /**

   * driver_register - register driver with bus
   * @drv: driver to register

   *

   * We pass off most of the work to the bus_add_driver() call,
   * since most of the things we have to do deal with the bus
   * structures.

   */

  int driver_register(struct device_driver *drv)

  {

  	int ret;

  	struct device_driver *other;

  	if (!drv->bus->p) {
  		pr_err("Driver '%s' was unable to register with bus_type '%s' because the bus was not initialized.
  ",
  			   drv->name, drv->bus->name);
  		return -EINVAL;
  	}

  	if ((drv->bus->probe && drv->probe) ||
  	    (drv->bus->remove && drv->remove) ||

  	    (drv->bus->shutdown && drv->shutdown))

  		pr_warn("Driver '%s' needs updating - please use "

  			"bus_type methods
  ", drv->name);

  
  	other = driver_find(drv->name, drv->bus);
  	if (other) {

  		pr_err("Error: Driver '%s' is already registered, "

  			"aborting...
  ", drv->name);

  		return -EBUSY;

  	}

  	ret = bus_add_driver(drv);
  	if (ret)
  		return ret;
  	ret = driver_add_groups(drv, drv->groups);

  	if (ret) {

  		bus_remove_driver(drv);

  		return ret;
  	}

  	kobject_uevent(&drv->p->kobj, KOBJ_ADD);

  	return ret;

  }

  EXPORT_SYMBOL_GPL(driver_register);

  /**

   * driver_unregister - remove driver from system.
   * @drv: driver.

   *

   * Again, we pass off most of the work to the bus-level call.

   */

  void driver_unregister(struct device_driver *drv)

  {

  	if (!drv || !drv->p) {
  		WARN(1, "Unexpected driver unregister!
  ");
  		return;
  	}

  	driver_remove_groups(drv, drv->groups);

  	bus_remove_driver(drv);

  }

  EXPORT_SYMBOL_GPL(driver_unregister);

  
  /**

   * driver_find - locate driver on a bus by its name.
   * @name: name of the driver.
   * @bus: bus to scan for the driver.

   *

   * Call kset_find_obj() to iterate over list of drivers on
   * a bus to find driver by name. Return driver if found.

   *

   * This routine provides no locking to prevent the driver it returns
   * from being unregistered or unloaded while the caller is using it.
   * The caller is responsible for preventing this.

   */
  struct device_driver *driver_find(const char *name, struct bus_type *bus)
  {

  	struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);

  	struct driver_private *priv;
  
  	if (k) {

  		/* Drop reference added by kset_find_obj() */
  		kobject_put(k);

  		priv = to_driver(k);
  		return priv->driver;
  	}

  	return NULL;
  }

  EXPORT_SYMBOL_GPL(driver_find);