1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * bus.h - the bus-specific portions of the driver model
4  *
5  * Copyright (c) 2001-2003 Patrick Mochel <mochel@osdl.org>
6  * Copyright (c) 2004-2009 Greg Kroah-Hartman <gregkh@suse.de>
7  * Copyright (c) 2008-2009 Novell Inc.
8  * Copyright (c) 2012-2019 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
9  * Copyright (c) 2012-2019 Linux Foundation
10  *
11  * See Documentation/driver-api/driver-model/ for more information.
12  */
13 
14 #ifndef _DEVICE_BUS_H_
15 #define _DEVICE_BUS_H_
16 
17 #include <linux/kobject.h>
18 #include <linux/klist.h>
19 #include <linux/pm.h>
20 
21 struct device_driver;
22 struct fwnode_handle;
23 
24 /**
25  * struct bus_type - The bus type of the device
26  *
27  * @name:	The name of the bus.
28  * @dev_name:	Used for subsystems to enumerate devices like ("foo%u", dev->id).
29  * @dev_root:	Default device to use as the parent.
30  * @bus_groups:	Default attributes of the bus.
31  * @dev_groups:	Default attributes of the devices on the bus.
32  * @drv_groups: Default attributes of the device drivers on the bus.
33  * @match:	Called, perhaps multiple times, whenever a new device or driver
34  *		is added for this bus. It should return a positive value if the
35  *		given device can be handled by the given driver and zero
36  *		otherwise. It may also return error code if determining that
37  *		the driver supports the device is not possible. In case of
38  *		-EPROBE_DEFER it will queue the device for deferred probing.
39  * @uevent:	Called when a device is added, removed, or a few other things
40  *		that generate uevents to add the environment variables.
41  * @probe:	Called when a new device or driver add to this bus, and callback
42  *		the specific driver's probe to initial the matched device.
43  * @sync_state:	Called to sync device state to software state after all the
44  *		state tracking consumers linked to this device (present at
45  *		the time of late_initcall) have successfully bound to a
46  *		driver. If the device has no consumers, this function will
47  *		be called at late_initcall_sync level. If the device has
48  *		consumers that are never bound to a driver, this function
49  *		will never get called until they do.
50  * @remove:	Called when a device removed from this bus.
51  * @shutdown:	Called at shut-down time to quiesce the device.
52  *
53  * @online:	Called to put the device back online (after offlining it).
54  * @offline:	Called to put the device offline for hot-removal. May fail.
55  *
56  * @suspend:	Called when a device on this bus wants to go to sleep mode.
57  * @resume:	Called to bring a device on this bus out of sleep mode.
58  * @num_vf:	Called to find out how many virtual functions a device on this
59  *		bus supports.
60  * @dma_configure:	Called to setup DMA configuration on a device on
61  *			this bus.
62  * @dma_cleanup:	Called to cleanup DMA configuration on a device on
63  *			this bus.
64  * @pm:		Power management operations of this bus, callback the specific
65  *		device driver's pm-ops.
66  * @iommu_ops:  IOMMU specific operations for this bus, used to attach IOMMU
67  *              driver implementations to a bus and allow the driver to do
68  *              bus-specific setup
69  * @lock_key:	Lock class key for use by the lock validator
70  * @need_parent_lock:	When probing or removing a device on this bus, the
71  *			device core should lock the device's parent.
72  *
73  * A bus is a channel between the processor and one or more devices. For the
74  * purposes of the device model, all devices are connected via a bus, even if
75  * it is an internal, virtual, "platform" bus. Buses can plug into each other.
76  * A USB controller is usually a PCI device, for example. The device model
77  * represents the actual connections between buses and the devices they control.
78  * A bus is represented by the bus_type structure. It contains the name, the
79  * default attributes, the bus' methods, PM operations, and the driver core's
80  * private data.
81  */
82 struct bus_type {
83 	const char		*name;
84 	const char		*dev_name;
85 	struct device		*dev_root;
86 	const struct attribute_group **bus_groups;
87 	const struct attribute_group **dev_groups;
88 	const struct attribute_group **drv_groups;
89 
90 	int (*match)(struct device *dev, struct device_driver *drv);
91 	int (*uevent)(const struct device *dev, struct kobj_uevent_env *env);
92 	int (*probe)(struct device *dev);
93 	void (*sync_state)(struct device *dev);
94 	void (*remove)(struct device *dev);
95 	void (*shutdown)(struct device *dev);
96 
97 	int (*online)(struct device *dev);
98 	int (*offline)(struct device *dev);
99 
100 	int (*suspend)(struct device *dev, pm_message_t state);
101 	int (*resume)(struct device *dev);
102 
103 	int (*num_vf)(struct device *dev);
104 
105 	int (*dma_configure)(struct device *dev);
106 	void (*dma_cleanup)(struct device *dev);
107 
108 	const struct dev_pm_ops *pm;
109 
110 	const struct iommu_ops *iommu_ops;
111 
112 	bool need_parent_lock;
113 };
114 
115 extern int __must_check bus_register(struct bus_type *bus);
116 
117 extern void bus_unregister(const struct bus_type *bus);
118 
119 extern int __must_check bus_rescan_devices(struct bus_type *bus);
120 
121 struct bus_attribute {
122 	struct attribute	attr;
123 	ssize_t (*show)(struct bus_type *bus, char *buf);
124 	ssize_t (*store)(struct bus_type *bus, const char *buf, size_t count);
125 };
126 
127 #define BUS_ATTR_RW(_name) \
128 	struct bus_attribute bus_attr_##_name = __ATTR_RW(_name)
129 #define BUS_ATTR_RO(_name) \
130 	struct bus_attribute bus_attr_##_name = __ATTR_RO(_name)
131 #define BUS_ATTR_WO(_name) \
132 	struct bus_attribute bus_attr_##_name = __ATTR_WO(_name)
133 
134 int __must_check bus_create_file(const struct bus_type *bus, struct bus_attribute *attr);
135 void bus_remove_file(const struct bus_type *bus, struct bus_attribute *attr);
136 
137 /* Generic device matching functions that all busses can use to match with */
138 int device_match_name(struct device *dev, const void *name);
139 int device_match_of_node(struct device *dev, const void *np);
140 int device_match_fwnode(struct device *dev, const void *fwnode);
141 int device_match_devt(struct device *dev, const void *pdevt);
142 int device_match_acpi_dev(struct device *dev, const void *adev);
143 int device_match_acpi_handle(struct device *dev, const void *handle);
144 int device_match_any(struct device *dev, const void *unused);
145 
146 /* iterator helpers for buses */
147 int bus_for_each_dev(const struct bus_type *bus, struct device *start, void *data,
148 		     int (*fn)(struct device *dev, void *data));
149 struct device *bus_find_device(const struct bus_type *bus, struct device *start,
150 			       const void *data,
151 			       int (*match)(struct device *dev, const void *data));
152 /**
153  * bus_find_device_by_name - device iterator for locating a particular device
154  * of a specific name.
155  * @bus: bus type
156  * @start: Device to begin with
157  * @name: name of the device to match
158  */
bus_find_device_by_name(const struct bus_type * bus,struct device * start,const char * name)159 static inline struct device *bus_find_device_by_name(const struct bus_type *bus,
160 						     struct device *start,
161 						     const char *name)
162 {
163 	return bus_find_device(bus, start, name, device_match_name);
164 }
165 
166 /**
167  * bus_find_device_by_of_node : device iterator for locating a particular device
168  * matching the of_node.
169  * @bus: bus type
170  * @np: of_node of the device to match.
171  */
172 static inline struct device *
bus_find_device_by_of_node(const struct bus_type * bus,const struct device_node * np)173 bus_find_device_by_of_node(const struct bus_type *bus, const struct device_node *np)
174 {
175 	return bus_find_device(bus, NULL, np, device_match_of_node);
176 }
177 
178 /**
179  * bus_find_device_by_fwnode : device iterator for locating a particular device
180  * matching the fwnode.
181  * @bus: bus type
182  * @fwnode: fwnode of the device to match.
183  */
184 static inline struct device *
bus_find_device_by_fwnode(const struct bus_type * bus,const struct fwnode_handle * fwnode)185 bus_find_device_by_fwnode(const struct bus_type *bus, const struct fwnode_handle *fwnode)
186 {
187 	return bus_find_device(bus, NULL, fwnode, device_match_fwnode);
188 }
189 
190 /**
191  * bus_find_device_by_devt : device iterator for locating a particular device
192  * matching the device type.
193  * @bus: bus type
194  * @devt: device type of the device to match.
195  */
bus_find_device_by_devt(const struct bus_type * bus,dev_t devt)196 static inline struct device *bus_find_device_by_devt(const struct bus_type *bus,
197 						     dev_t devt)
198 {
199 	return bus_find_device(bus, NULL, &devt, device_match_devt);
200 }
201 
202 /**
203  * bus_find_next_device - Find the next device after a given device in a
204  * given bus.
205  * @bus: bus type
206  * @cur: device to begin the search with.
207  */
208 static inline struct device *
bus_find_next_device(const struct bus_type * bus,struct device * cur)209 bus_find_next_device(const struct bus_type *bus,struct device *cur)
210 {
211 	return bus_find_device(bus, cur, NULL, device_match_any);
212 }
213 
214 #ifdef CONFIG_ACPI
215 struct acpi_device;
216 
217 /**
218  * bus_find_device_by_acpi_dev : device iterator for locating a particular device
219  * matching the ACPI COMPANION device.
220  * @bus: bus type
221  * @adev: ACPI COMPANION device to match.
222  */
223 static inline struct device *
bus_find_device_by_acpi_dev(const struct bus_type * bus,const struct acpi_device * adev)224 bus_find_device_by_acpi_dev(const struct bus_type *bus, const struct acpi_device *adev)
225 {
226 	return bus_find_device(bus, NULL, adev, device_match_acpi_dev);
227 }
228 #else
229 static inline struct device *
bus_find_device_by_acpi_dev(const struct bus_type * bus,const void * adev)230 bus_find_device_by_acpi_dev(const struct bus_type *bus, const void *adev)
231 {
232 	return NULL;
233 }
234 #endif
235 
236 int bus_for_each_drv(const struct bus_type *bus, struct device_driver *start,
237 		     void *data, int (*fn)(struct device_driver *, void *));
238 void bus_sort_breadthfirst(struct bus_type *bus,
239 			   int (*compare)(const struct device *a,
240 					  const struct device *b));
241 /*
242  * Bus notifiers: Get notified of addition/removal of devices
243  * and binding/unbinding of drivers to devices.
244  * In the long run, it should be a replacement for the platform
245  * notify hooks.
246  */
247 struct notifier_block;
248 
249 extern int bus_register_notifier(const struct bus_type *bus,
250 				 struct notifier_block *nb);
251 extern int bus_unregister_notifier(const struct bus_type *bus,
252 				   struct notifier_block *nb);
253 
254 /**
255  * enum bus_notifier_event - Bus Notifier events that have happened
256  * @BUS_NOTIFY_ADD_DEVICE: device is added to this bus
257  * @BUS_NOTIFY_DEL_DEVICE: device is about to be removed from this bus
258  * @BUS_NOTIFY_REMOVED_DEVICE: device is successfully removed from this bus
259  * @BUS_NOTIFY_BIND_DRIVER: a driver is about to be bound to this device on this bus
260  * @BUS_NOTIFY_BOUND_DRIVER: a driver is successfully bound to this device on this bus
261  * @BUS_NOTIFY_UNBIND_DRIVER: a driver is about to be unbound from this device on this bus
262  * @BUS_NOTIFY_UNBOUND_DRIVER: a driver is successfully unbound from this device on this bus
263  * @BUS_NOTIFY_DRIVER_NOT_BOUND: a driver failed to be bound to this device on this bus
264  *
265  * These are the value passed to a bus notifier when a specific event happens.
266  *
267  * Note that bus notifiers are likely to be called with the device lock already
268  * held by the driver core, so be careful in any notifier callback as to what
269  * you do with the device structure.
270  *
271  * All bus notifiers are called with the target struct device * as an argument.
272  */
273 enum bus_notifier_event {
274 	BUS_NOTIFY_ADD_DEVICE,
275 	BUS_NOTIFY_DEL_DEVICE,
276 	BUS_NOTIFY_REMOVED_DEVICE,
277 	BUS_NOTIFY_BIND_DRIVER,
278 	BUS_NOTIFY_BOUND_DRIVER,
279 	BUS_NOTIFY_UNBIND_DRIVER,
280 	BUS_NOTIFY_UNBOUND_DRIVER,
281 	BUS_NOTIFY_DRIVER_NOT_BOUND,
282 };
283 
284 extern struct kset *bus_get_kset(const struct bus_type *bus);
285 struct device *bus_get_dev_root(const struct bus_type *bus);
286 
287 #endif
288