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  * @p:		The private data of the driver core, only the driver core can
70  *		touch this.
71  * @lock_key:	Lock class key for use by the lock validator
72  * @need_parent_lock:	When probing or removing a device on this bus, the
73  *			device core should lock the device's parent.
74  *
75  * A bus is a channel between the processor and one or more devices. For the
76  * purposes of the device model, all devices are connected via a bus, even if
77  * it is an internal, virtual, "platform" bus. Buses can plug into each other.
78  * A USB controller is usually a PCI device, for example. The device model
79  * represents the actual connections between buses and the devices they control.
80  * A bus is represented by the bus_type structure. It contains the name, the
81  * default attributes, the bus' methods, PM operations, and the driver core's
82  * private data.
83  */
84 struct bus_type {
85 	const char		*name;
86 	const char		*dev_name;
87 	struct device		*dev_root;
88 	const struct attribute_group **bus_groups;
89 	const struct attribute_group **dev_groups;
90 	const struct attribute_group **drv_groups;
91 
92 	int (*match)(struct device *dev, struct device_driver *drv);
93 	int (*uevent)(struct device *dev, struct kobj_uevent_env *env);
94 	int (*probe)(struct device *dev);
95 	void (*sync_state)(struct device *dev);
96 	void (*remove)(struct device *dev);
97 	void (*shutdown)(struct device *dev);
98 
99 	int (*online)(struct device *dev);
100 	int (*offline)(struct device *dev);
101 
102 	int (*suspend)(struct device *dev, pm_message_t state);
103 	int (*resume)(struct device *dev);
104 
105 	int (*num_vf)(struct device *dev);
106 
107 	int (*dma_configure)(struct device *dev);
108 	void (*dma_cleanup)(struct device *dev);
109 
110 	const struct dev_pm_ops *pm;
111 
112 	const struct iommu_ops *iommu_ops;
113 
114 	struct subsys_private *p;
115 	struct lock_class_key lock_key;
116 
117 	bool need_parent_lock;
118 };
119 
120 extern int __must_check bus_register(struct bus_type *bus);
121 
122 extern void bus_unregister(struct bus_type *bus);
123 
124 extern int __must_check bus_rescan_devices(struct bus_type *bus);
125 
126 struct bus_attribute {
127 	struct attribute	attr;
128 	ssize_t (*show)(struct bus_type *bus, char *buf);
129 	ssize_t (*store)(struct bus_type *bus, const char *buf, size_t count);
130 };
131 
132 #define BUS_ATTR_RW(_name) \
133 	struct bus_attribute bus_attr_##_name = __ATTR_RW(_name)
134 #define BUS_ATTR_RO(_name) \
135 	struct bus_attribute bus_attr_##_name = __ATTR_RO(_name)
136 #define BUS_ATTR_WO(_name) \
137 	struct bus_attribute bus_attr_##_name = __ATTR_WO(_name)
138 
139 extern int __must_check bus_create_file(struct bus_type *,
140 					struct bus_attribute *);
141 extern void bus_remove_file(struct bus_type *, struct bus_attribute *);
142 
143 /* Generic device matching functions that all busses can use to match with */
144 int device_match_name(struct device *dev, const void *name);
145 int device_match_of_node(struct device *dev, const void *np);
146 int device_match_fwnode(struct device *dev, const void *fwnode);
147 int device_match_devt(struct device *dev, const void *pdevt);
148 int device_match_acpi_dev(struct device *dev, const void *adev);
149 int device_match_acpi_handle(struct device *dev, const void *handle);
150 int device_match_any(struct device *dev, const void *unused);
151 
152 /* iterator helpers for buses */
153 struct subsys_dev_iter {
154 	struct klist_iter		ki;
155 	const struct device_type	*type;
156 };
157 void subsys_dev_iter_init(struct subsys_dev_iter *iter,
158 			 struct bus_type *subsys,
159 			 struct device *start,
160 			 const struct device_type *type);
161 struct device *subsys_dev_iter_next(struct subsys_dev_iter *iter);
162 void subsys_dev_iter_exit(struct subsys_dev_iter *iter);
163 
164 int bus_for_each_dev(struct bus_type *bus, struct device *start, void *data,
165 		     int (*fn)(struct device *dev, void *data));
166 struct device *bus_find_device(struct bus_type *bus, struct device *start,
167 			       const void *data,
168 			       int (*match)(struct device *dev, const void *data));
169 /**
170  * bus_find_device_by_name - device iterator for locating a particular device
171  * of a specific name.
172  * @bus: bus type
173  * @start: Device to begin with
174  * @name: name of the device to match
175  */
bus_find_device_by_name(struct bus_type * bus,struct device * start,const char * name)176 static inline struct device *bus_find_device_by_name(struct bus_type *bus,
177 						     struct device *start,
178 						     const char *name)
179 {
180 	return bus_find_device(bus, start, name, device_match_name);
181 }
182 
183 /**
184  * bus_find_device_by_of_node : device iterator for locating a particular device
185  * matching the of_node.
186  * @bus: bus type
187  * @np: of_node of the device to match.
188  */
189 static inline struct device *
bus_find_device_by_of_node(struct bus_type * bus,const struct device_node * np)190 bus_find_device_by_of_node(struct bus_type *bus, const struct device_node *np)
191 {
192 	return bus_find_device(bus, NULL, np, device_match_of_node);
193 }
194 
195 /**
196  * bus_find_device_by_fwnode : device iterator for locating a particular device
197  * matching the fwnode.
198  * @bus: bus type
199  * @fwnode: fwnode of the device to match.
200  */
201 static inline struct device *
bus_find_device_by_fwnode(struct bus_type * bus,const struct fwnode_handle * fwnode)202 bus_find_device_by_fwnode(struct bus_type *bus, const struct fwnode_handle *fwnode)
203 {
204 	return bus_find_device(bus, NULL, fwnode, device_match_fwnode);
205 }
206 
207 /**
208  * bus_find_device_by_devt : device iterator for locating a particular device
209  * matching the device type.
210  * @bus: bus type
211  * @devt: device type of the device to match.
212  */
bus_find_device_by_devt(struct bus_type * bus,dev_t devt)213 static inline struct device *bus_find_device_by_devt(struct bus_type *bus,
214 						     dev_t devt)
215 {
216 	return bus_find_device(bus, NULL, &devt, device_match_devt);
217 }
218 
219 /**
220  * bus_find_next_device - Find the next device after a given device in a
221  * given bus.
222  * @bus: bus type
223  * @cur: device to begin the search with.
224  */
225 static inline struct device *
bus_find_next_device(struct bus_type * bus,struct device * cur)226 bus_find_next_device(struct bus_type *bus,struct device *cur)
227 {
228 	return bus_find_device(bus, cur, NULL, device_match_any);
229 }
230 
231 #ifdef CONFIG_ACPI
232 struct acpi_device;
233 
234 /**
235  * bus_find_device_by_acpi_dev : device iterator for locating a particular device
236  * matching the ACPI COMPANION device.
237  * @bus: bus type
238  * @adev: ACPI COMPANION device to match.
239  */
240 static inline struct device *
bus_find_device_by_acpi_dev(struct bus_type * bus,const struct acpi_device * adev)241 bus_find_device_by_acpi_dev(struct bus_type *bus, const struct acpi_device *adev)
242 {
243 	return bus_find_device(bus, NULL, adev, device_match_acpi_dev);
244 }
245 #else
246 static inline struct device *
bus_find_device_by_acpi_dev(struct bus_type * bus,const void * adev)247 bus_find_device_by_acpi_dev(struct bus_type *bus, const void *adev)
248 {
249 	return NULL;
250 }
251 #endif
252 
253 struct device *subsys_find_device_by_id(struct bus_type *bus, unsigned int id,
254 					struct device *hint);
255 int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
256 		     void *data, int (*fn)(struct device_driver *, void *));
257 void bus_sort_breadthfirst(struct bus_type *bus,
258 			   int (*compare)(const struct device *a,
259 					  const struct device *b));
260 /*
261  * Bus notifiers: Get notified of addition/removal of devices
262  * and binding/unbinding of drivers to devices.
263  * In the long run, it should be a replacement for the platform
264  * notify hooks.
265  */
266 struct notifier_block;
267 
268 extern int bus_register_notifier(struct bus_type *bus,
269 				 struct notifier_block *nb);
270 extern int bus_unregister_notifier(struct bus_type *bus,
271 				   struct notifier_block *nb);
272 
273 /* All 4 notifers below get called with the target struct device *
274  * as an argument. Note that those functions are likely to be called
275  * with the device lock held in the core, so be careful.
276  */
277 #define BUS_NOTIFY_ADD_DEVICE		0x00000001 /* device added */
278 #define BUS_NOTIFY_DEL_DEVICE		0x00000002 /* device to be removed */
279 #define BUS_NOTIFY_REMOVED_DEVICE	0x00000003 /* device removed */
280 #define BUS_NOTIFY_BIND_DRIVER		0x00000004 /* driver about to be
281 						      bound */
282 #define BUS_NOTIFY_BOUND_DRIVER		0x00000005 /* driver bound to device */
283 #define BUS_NOTIFY_UNBIND_DRIVER	0x00000006 /* driver about to be
284 						      unbound */
285 #define BUS_NOTIFY_UNBOUND_DRIVER	0x00000007 /* driver is unbound
286 						      from the device */
287 #define BUS_NOTIFY_DRIVER_NOT_BOUND	0x00000008 /* driver fails to be bound */
288 
289 extern struct kset *bus_get_kset(struct bus_type *bus);
290 extern struct klist *bus_get_device_klist(struct bus_type *bus);
291 
292 #endif
293