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 <[email protected]> 6 * Copyright (c) 2004-2009 Greg Kroah-Hartman <[email protected]> 7 * Copyright (c) 2008-2009 Novell Inc. 8 * Copyright (c) 2012-2019 Greg Kroah-Hartman <[email protected]> 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 * @need_parent_lock: When probing or removing a device on this bus, the 66 * device core should lock the device's parent. 67 * 68 * A bus is a channel between the processor and one or more devices. For the 69 * purposes of the device model, all devices are connected via a bus, even if 70 * it is an internal, virtual, "platform" bus. Buses can plug into each other. 71 * A USB controller is usually a PCI device, for example. The device model 72 * represents the actual connections between buses and the devices they control. 73 * A bus is represented by the bus_type structure. It contains the name, the 74 * default attributes, the bus' methods, PM operations, and the driver core's 75 * private data. 76 */ 77 struct bus_type { 78 const char *name; 79 const char *dev_name; 80 const struct attribute_group **bus_groups; 81 const struct attribute_group **dev_groups; 82 const struct attribute_group **drv_groups; 83 84 int (*match)(struct device *dev, const struct device_driver *drv); 85 int (*uevent)(const struct device *dev, struct kobj_uevent_env *env); 86 int (*probe)(struct device *dev); 87 void (*sync_state)(struct device *dev); 88 void (*remove)(struct device *dev); 89 void (*shutdown)(struct device *dev); 90 91 int (*online)(struct device *dev); 92 int (*offline)(struct device *dev); 93 94 int (*suspend)(struct device *dev, pm_message_t state); 95 int (*resume)(struct device *dev); 96 97 int (*num_vf)(struct device *dev); 98 99 int (*dma_configure)(struct device *dev); 100 void (*dma_cleanup)(struct device *dev); 101 102 const struct dev_pm_ops *pm; 103 104 bool need_parent_lock; 105 }; 106 107 int __must_check bus_register(const struct bus_type *bus); 108 109 void bus_unregister(const struct bus_type *bus); 110 111 int __must_check bus_rescan_devices(const struct bus_type *bus); 112 113 struct bus_attribute { 114 struct attribute attr; 115 ssize_t (*show)(const struct bus_type *bus, char *buf); 116 ssize_t (*store)(const struct bus_type *bus, const char *buf, size_t count); 117 }; 118 119 #define BUS_ATTR_RW(_name) \ 120 struct bus_attribute bus_attr_##_name = __ATTR_RW(_name) 121 #define BUS_ATTR_RO(_name) \ 122 struct bus_attribute bus_attr_##_name = __ATTR_RO(_name) 123 #define BUS_ATTR_WO(_name) \ 124 struct bus_attribute bus_attr_##_name = __ATTR_WO(_name) 125 126 int __must_check bus_create_file(const struct bus_type *bus, struct bus_attribute *attr); 127 void bus_remove_file(const struct bus_type *bus, struct bus_attribute *attr); 128 129 /* Matching function type for drivers/base APIs to find a specific device */ 130 typedef int (*device_match_t)(struct device *dev, const void *data); 131 132 /* Generic device matching functions that all busses can use to match with */ 133 int device_match_name(struct device *dev, const void *name); 134 int device_match_type(struct device *dev, const void *type); 135 int device_match_of_node(struct device *dev, const void *np); 136 int device_match_fwnode(struct device *dev, const void *fwnode); 137 int device_match_devt(struct device *dev, const void *pdevt); 138 int device_match_acpi_dev(struct device *dev, const void *adev); 139 int device_match_acpi_handle(struct device *dev, const void *handle); 140 int device_match_any(struct device *dev, const void *unused); 141 142 /* Device iterating function type for various driver core for_each APIs */ 143 typedef int (*device_iter_t)(struct device *dev, void *data); 144 145 /* iterator helpers for buses */ 146 int bus_for_each_dev(const struct bus_type *bus, struct device *start, 147 void *data, device_iter_t fn); 148 struct device *bus_find_device(const struct bus_type *bus, struct device *start, 149 const void *data, device_match_t match); 150 /** 151 * bus_find_device_by_name - device iterator for locating a particular device 152 * of a specific name. 153 * @bus: bus type 154 * @start: Device to begin with 155 * @name: name of the device to match 156 */ 157 static inline struct device *bus_find_device_by_name(const struct bus_type *bus, 158 struct device *start, 159 const char *name) 160 { 161 return bus_find_device(bus, start, name, device_match_name); 162 } 163 164 /** 165 * bus_find_device_by_of_node : device iterator for locating a particular device 166 * matching the of_node. 167 * @bus: bus type 168 * @np: of_node of the device to match. 169 */ 170 static inline struct device * 171 bus_find_device_by_of_node(const struct bus_type *bus, const struct device_node *np) 172 { 173 return bus_find_device(bus, NULL, np, device_match_of_node); 174 } 175 176 /** 177 * bus_find_device_by_fwnode : device iterator for locating a particular device 178 * matching the fwnode. 179 * @bus: bus type 180 * @fwnode: fwnode of the device to match. 181 */ 182 static inline struct device * 183 bus_find_device_by_fwnode(const struct bus_type *bus, const struct fwnode_handle *fwnode) 184 { 185 return bus_find_device(bus, NULL, fwnode, device_match_fwnode); 186 } 187 188 /** 189 * bus_find_device_by_devt : device iterator for locating a particular device 190 * matching the device type. 191 * @bus: bus type 192 * @devt: device type of the device to match. 193 */ 194 static inline struct device *bus_find_device_by_devt(const struct bus_type *bus, 195 dev_t devt) 196 { 197 return bus_find_device(bus, NULL, &devt, device_match_devt); 198 } 199 200 /** 201 * bus_find_next_device - Find the next device after a given device in a 202 * given bus. 203 * @bus: bus type 204 * @cur: device to begin the search with. 205 */ 206 static inline struct device * 207 bus_find_next_device(const struct bus_type *bus,struct device *cur) 208 { 209 return bus_find_device(bus, cur, NULL, device_match_any); 210 } 211 212 #ifdef CONFIG_ACPI 213 struct acpi_device; 214 215 /** 216 * bus_find_device_by_acpi_dev : device iterator for locating a particular device 217 * matching the ACPI COMPANION device. 218 * @bus: bus type 219 * @adev: ACPI COMPANION device to match. 220 */ 221 static inline struct device * 222 bus_find_device_by_acpi_dev(const struct bus_type *bus, const struct acpi_device *adev) 223 { 224 return bus_find_device(bus, NULL, adev, device_match_acpi_dev); 225 } 226 #else 227 static inline struct device * 228 bus_find_device_by_acpi_dev(const struct bus_type *bus, const void *adev) 229 { 230 return NULL; 231 } 232 #endif 233 234 int bus_for_each_drv(const struct bus_type *bus, struct device_driver *start, 235 void *data, int (*fn)(struct device_driver *, void *)); 236 void bus_sort_breadthfirst(const struct bus_type *bus, 237 int (*compare)(const struct device *a, 238 const struct device *b)); 239 /* 240 * Bus notifiers: Get notified of addition/removal of devices 241 * and binding/unbinding of drivers to devices. 242 * In the long run, it should be a replacement for the platform 243 * notify hooks. 244 */ 245 struct notifier_block; 246 247 int bus_register_notifier(const struct bus_type *bus, struct notifier_block *nb); 248 int bus_unregister_notifier(const struct bus_type *bus, struct notifier_block *nb); 249 250 /** 251 * enum bus_notifier_event - Bus Notifier events that have happened 252 * @BUS_NOTIFY_ADD_DEVICE: device is added to this bus 253 * @BUS_NOTIFY_DEL_DEVICE: device is about to be removed from this bus 254 * @BUS_NOTIFY_REMOVED_DEVICE: device is successfully removed from this bus 255 * @BUS_NOTIFY_BIND_DRIVER: a driver is about to be bound to this device on this bus 256 * @BUS_NOTIFY_BOUND_DRIVER: a driver is successfully bound to this device on this bus 257 * @BUS_NOTIFY_UNBIND_DRIVER: a driver is about to be unbound from this device on this bus 258 * @BUS_NOTIFY_UNBOUND_DRIVER: a driver is successfully unbound from this device on this bus 259 * @BUS_NOTIFY_DRIVER_NOT_BOUND: a driver failed to be bound to this device on this bus 260 * 261 * These are the value passed to a bus notifier when a specific event happens. 262 * 263 * Note that bus notifiers are likely to be called with the device lock already 264 * held by the driver core, so be careful in any notifier callback as to what 265 * you do with the device structure. 266 * 267 * All bus notifiers are called with the target struct device * as an argument. 268 */ 269 enum bus_notifier_event { 270 BUS_NOTIFY_ADD_DEVICE, 271 BUS_NOTIFY_DEL_DEVICE, 272 BUS_NOTIFY_REMOVED_DEVICE, 273 BUS_NOTIFY_BIND_DRIVER, 274 BUS_NOTIFY_BOUND_DRIVER, 275 BUS_NOTIFY_UNBIND_DRIVER, 276 BUS_NOTIFY_UNBOUND_DRIVER, 277 BUS_NOTIFY_DRIVER_NOT_BOUND, 278 }; 279 280 struct kset *bus_get_kset(const struct bus_type *bus); 281 struct device *bus_get_dev_root(const struct bus_type *bus); 282 283 #endif 284