text: // SPDX-License-Identifier: GPL-2.0
  /*
   * bus.h - the bus-specific portions of the driver model
   *
   * Copyright (c) 2001-2003 Patrick Mochel <mochel@osdl.org>
   * Copyright (c) 2004-2009 Greg Kroah-Hartman <gregkh@suse.de>
   * Copyright (c) 2008-2009 Novell Inc.
   * Copyright (c) 2012-2019 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
   * Copyright (c) 2012-2019 Linux Foundation
   *
   * See Documentation/driver-api/driver-model/ for more information.
   */
  
  #ifndef _DEVICE_BUS_H_
  #define _DEVICE_BUS_H_
  
  #include <linux/kobject.h>
  #include <linux/klist.h>
  #include <linux/pm.h>
  
  struct device_driver;
  struct fwnode_handle;
  
  /**
   * struct bus_type - The bus type of the device
   *
   * @name:	The name of the bus.
   * @dev_name:	Used for subsystems to enumerate devices like ("foo%u", dev->id).
   * @dev_root:	Default device to use as the parent.
   * @bus_groups:	Default attributes of the bus.
   * @dev_groups:	Default attributes of the devices on the bus.
   * @drv_groups: Default attributes of the device drivers on the bus.
   * @match:	Called, perhaps multiple times, whenever a new device or driver
   *		is added for this bus. It should return a positive value if the
   *		given device can be handled by the given driver and zero
   *		otherwise. It may also return error code if determining that
   *		the driver supports the device is not possible. In case of
   *		-EPROBE_DEFER it will queue the device for deferred probing.
   * @uevent:	Called when a device is added, removed, or a few other things
   *		that generate uevents to add the environment variables.
   * @probe:	Called when a new device or driver add to this bus, and callback
   *		the specific driver's probe to initial the matched device.
   * @sync_state:	Called to sync device state to software state after all the
   *		state tracking consumers linked to this device (present at
   *		the time of late_initcall) have successfully bound to a
   *		driver. If the device has no consumers, this function will
   *		be called at late_initcall_sync level. If the device has
   *		consumers that are never bound to a driver, this function
   *		will never get called until they do.
   * @remove:	Called when a device removed from this bus.
   * @shutdown:	Called at shut-down time to quiesce the device.
   *
   * @online:	Called to put the device back online (after offlining it).
   * @offline:	Called to put the device offline for hot-removal. May fail.
   *
   * @suspend:	Called when a device on this bus wants to go to sleep mode.
   * @resume:	Called to bring a device on this bus out of sleep mode.
   * @num_vf:	Called to find out how many virtual functions a device on this
   *		bus supports.
   * @dma_configure:	Called to setup DMA configuration on a device on
   *			this bus.
   * @pm:		Power management operations of this bus, callback the specific
   *		device driver's pm-ops.
   * @iommu_ops:  IOMMU specific operations for this bus, used to attach IOMMU
   *              driver implementations to a bus and allow the driver to do
   *              bus-specific setup
   * @p:		The private data of the driver core, only the driver core can
   *		touch this.
   * @lock_key:	Lock class key for use by the lock validator
   * @need_parent_lock:	When probing or removing a device on this bus, the
   *			device core should lock the device's parent.
   *
   * A bus is a channel between the processor and one or more devices. For the
   * purposes of the device model, all devices are connected via a bus, even if
   * it is an internal, virtual, "platform" bus. Buses can plug into each other.
   * A USB controller is usually a PCI device, for example. The device model
   * represents the actual connections between buses and the devices they control.
   * A bus is represented by the bus_type structure. It contains the name, the
   * default attributes, the bus' methods, PM operations, and the driver core's
   * private data.
   */
  struct bus_type {
  	const char		*name;
  	const char		*dev_name;
  	struct device		*dev_root;
  	const struct attribute_group **bus_groups;
  	const struct attribute_group **dev_groups;
  	const struct attribute_group **drv_groups;
  
  	int (*match)(struct device *dev, struct device_driver *drv);
  	int (*uevent)(struct device *dev, struct kobj_uevent_env *env);
  	int (*probe)(struct device *dev);
  	void (*sync_state)(struct device *dev);
  	void (*remove)(struct device *dev);
  	void (*shutdown)(struct device *dev);
  
  	int (*online)(struct device *dev);
  	int (*offline)(struct device *dev);
  
  	int (*suspend)(struct device *dev, pm_message_t state);
  	int (*resume)(struct device *dev);
  
  	int (*num_vf)(struct device *dev);
  
  	int (*dma_configure)(struct device *dev);
  
  	const struct dev_pm_ops *pm;
  
  	const struct iommu_ops *iommu_ops;
  
  	struct subsys_private *p;
  	struct lock_class_key lock_key;
  
  	bool need_parent_lock;
  };
  
  extern int __must_check bus_register(struct bus_type *bus);
  
  extern void bus_unregister(struct bus_type *bus);
  
  extern int __must_check bus_rescan_devices(struct bus_type *bus);
  
  struct bus_attribute {
  	struct attribute	attr;
  	ssize_t (*show)(struct bus_type *bus, char *buf);
  	ssize_t (*store)(struct bus_type *bus, const char *buf, size_t count);
  };
  
  #define BUS_ATTR_RW(_name) \
  	struct bus_attribute bus_attr_##_name = __ATTR_RW(_name)
  #define BUS_ATTR_RO(_name) \
  	struct bus_attribute bus_attr_##_name = __ATTR_RO(_name)
  #define BUS_ATTR_WO(_name) \
  	struct bus_attribute bus_attr_##_name = __ATTR_WO(_name)
  
  extern int __must_check bus_create_file(struct bus_type *,
  					struct bus_attribute *);
  extern void bus_remove_file(struct bus_type *, struct bus_attribute *);
  
  /* Generic device matching functions that all busses can use to match with */
  int device_match_name(struct device *dev, const void *name);
  int device_match_of_node(struct device *dev, const void *np);
  int device_match_fwnode(struct device *dev, const void *fwnode);
  int device_match_devt(struct device *dev, const void *pdevt);
  int device_match_acpi_dev(struct device *dev, const void *adev);
  int device_match_any(struct device *dev, const void *unused);
  
  /* iterator helpers for buses */
  struct subsys_dev_iter {
  	struct klist_iter		ki;
  	const struct device_type	*type;
  };
  void subsys_dev_iter_init(struct subsys_dev_iter *iter,
  			 struct bus_type *subsys,
  			 struct device *start,
  			 const struct device_type *type);
  struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter);
  void subsys_dev_iter_exit(struct subsys_dev_iter *iter);
  
  int bus_for_each_dev(struct bus_type *bus, struct device *start, void *data,
  		     int (*fn)(struct device *dev, void *data));
  struct device *bus_find_device(struct bus_type *bus, struct device *start,
  			       const void *data,
  			       int (*match)(struct device *dev, const void *data));
  /**
   * bus_find_device_by_name - device iterator for locating a particular device
   * of a specific name.
   * @bus: bus type
   * @start: Device to begin with
   * @name: name of the device to match
   */
  static inline struct device *bus_find_device_by_name(struct bus_type *bus,
  						     struct device *start,
  						     const char *name)
  {
  	return bus_find_device(bus, start, name, device_match_name);
  }
  
  /**
   * bus_find_device_by_of_node : device iterator for locating a particular device
   * matching the of_node.
   * @bus: bus type
   * @np: of_node of the device to match.
   */
  static inline struct device *
  bus_find_device_by_of_node(struct bus_type *bus, const struct device_node *np)
  {
  	return bus_find_device(bus, NULL, np, device_match_of_node);
  }
  
  /**
   * bus_find_device_by_fwnode : device iterator for locating a particular device
   * matching the fwnode.
   * @bus: bus type
   * @fwnode: fwnode of the device to match.
   */
  static inline struct device *
  bus_find_device_by_fwnode(struct bus_type *bus, const struct fwnode_handle *fwnode)
  {
  	return bus_find_device(bus, NULL, fwnode, device_match_fwnode);
  }
  
  /**
   * bus_find_device_by_devt : device iterator for locating a particular device
   * matching the device type.
   * @bus: bus type
   * @devt: device type of the device to match.
   */
  static inline struct device *bus_find_device_by_devt(struct bus_type *bus,
  						     dev_t devt)
  {
  	return bus_find_device(bus, NULL, &devt, device_match_devt);
  }
  
  /**
   * bus_find_next_device - Find the next device after a given device in a
   * given bus.
   * @bus: bus type
   * @cur: device to begin the search with.
   */
  static inline struct device *
  bus_find_next_device(struct bus_type *bus,struct device *cur)
  {
  	return bus_find_device(bus, cur, NULL, device_match_any);
  }
  
  #ifdef CONFIG_ACPI
  struct acpi_device;
  
  /**
   * bus_find_device_by_acpi_dev : device iterator for locating a particular device
   * matching the ACPI COMPANION device.
   * @bus: bus type
   * @adev: ACPI COMPANION device to match.
   */
  static inline struct device *
  bus_find_device_by_acpi_dev(struct bus_type *bus, const struct acpi_device *adev)
  {
  	return bus_find_device(bus, NULL, adev, device_match_acpi_dev);
  }
  #else
  static inline struct device *
  bus_find_device_by_acpi_dev(struct bus_type *bus, const void *adev)
  {
  	return NULL;
  }
  #endif
  
  struct device *subsys_find_device_by_id(struct bus_type *bus, unsigned int id,
  					struct device *hint);
  int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
  		     void *data, int (*fn)(struct device_driver *, void *));
  void bus_sort_breadthfirst(struct bus_type *bus,
  			   int (*compare)(const struct device *a,
  					  const struct device *b));
  /*
   * Bus notifiers: Get notified of addition/removal of devices
   * and binding/unbinding of drivers to devices.
   * In the long run, it should be a replacement for the platform
   * notify hooks.
   */
  struct notifier_block;
  
  extern int bus_register_notifier(struct bus_type *bus,
  				 struct notifier_block *nb);
  extern int bus_unregister_notifier(struct bus_type *bus,
  				   struct notifier_block *nb);
  
  /* All 4 notifers below get called with the target struct device *
   * as an argument. Note that those functions are likely to be called
   * with the device lock held in the core, so be careful.
   */
  #define BUS_NOTIFY_ADD_DEVICE		0x00000001 /* device added */
  #define BUS_NOTIFY_DEL_DEVICE		0x00000002 /* device to be removed */
  #define BUS_NOTIFY_REMOVED_DEVICE	0x00000003 /* device removed */
  #define BUS_NOTIFY_BIND_DRIVER		0x00000004 /* driver about to be
  						      bound */
  #define BUS_NOTIFY_BOUND_DRIVER		0x00000005 /* driver bound to device */
  #define BUS_NOTIFY_UNBIND_DRIVER	0x00000006 /* driver about to be
  						      unbound */
  #define BUS_NOTIFY_UNBOUND_DRIVER	0x00000007 /* driver is unbound
  						      from the device */
  #define BUS_NOTIFY_DRIVER_NOT_BOUND	0x00000008 /* driver fails to be bound */
  
  extern struct kset *bus_get_kset(struct bus_type *bus);
  extern struct klist *bus_get_device_klist(struct bus_type *bus);
  
  #endif
  