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