1 /* 2 * driver.c - centralized device driver management 3 * 4 * Copyright (c) 2002-3 Patrick Mochel 5 * Copyright (c) 2002-3 Open Source Development Labs 6 * 7 * This file is released under the GPLv2 8 * 9 */ 10 11 #include <linux/config.h> 12 #include <linux/device.h> 13 #include <linux/module.h> 14 #include <linux/errno.h> 15 #include <linux/string.h> 16 #include "base.h" 17 18 #define to_dev(node) container_of(node, struct device, driver_list) 19 #define to_drv(obj) container_of(obj, struct device_driver, kobj) 20 21 22 static struct device * next_device(struct klist_iter * i) 23 { 24 struct klist_node * n = klist_next(i); 25 return n ? container_of(n, struct device, knode_driver) : NULL; 26 } 27 28 /** 29 * driver_for_each_device - Iterator for devices bound to a driver. 30 * @drv: Driver we're iterating. 31 * @data: Data to pass to the callback. 32 * @fn: Function to call for each device. 33 * 34 * Iterate over the @drv's list of devices calling @fn for each one. 35 */ 36 37 int driver_for_each_device(struct device_driver * drv, struct device * start, 38 void * data, int (*fn)(struct device *, void *)) 39 { 40 struct klist_iter i; 41 struct device * dev; 42 int error = 0; 43 44 if (!drv) 45 return -EINVAL; 46 47 klist_iter_init_node(&drv->klist_devices, &i, 48 start ? &start->knode_driver : NULL); 49 while ((dev = next_device(&i)) && !error) 50 error = fn(dev, data); 51 klist_iter_exit(&i); 52 return error; 53 } 54 55 EXPORT_SYMBOL_GPL(driver_for_each_device); 56 57 58 /** 59 * driver_find_device - device iterator for locating a particular device. 60 * @driver: The device's driver 61 * @start: Device to begin with 62 * @data: Data to pass to match function 63 * @match: Callback function to check device 64 * 65 * This is similar to the driver_for_each_device() function above, but 66 * it returns a reference to a device that is 'found' for later use, as 67 * determined by the @match callback. 68 * 69 * The callback should return 0 if the device doesn't match and non-zero 70 * if it does. If the callback returns non-zero, this function will 71 * return to the caller and not iterate over any more devices. 72 */ 73 struct device * driver_find_device(struct device_driver *drv, 74 struct device * start, void * data, 75 int (*match)(struct device *, void *)) 76 { 77 struct klist_iter i; 78 struct device *dev; 79 80 if (!drv) 81 return NULL; 82 83 klist_iter_init_node(&drv->klist_devices, &i, 84 (start ? &start->knode_driver : NULL)); 85 while ((dev = next_device(&i))) 86 if (match(dev, data) && get_device(dev)) 87 break; 88 klist_iter_exit(&i); 89 return dev; 90 } 91 EXPORT_SYMBOL_GPL(driver_find_device); 92 93 /** 94 * driver_create_file - create sysfs file for driver. 95 * @drv: driver. 96 * @attr: driver attribute descriptor. 97 */ 98 99 int driver_create_file(struct device_driver * drv, struct driver_attribute * attr) 100 { 101 int error; 102 if (get_driver(drv)) { 103 error = sysfs_create_file(&drv->kobj, &attr->attr); 104 put_driver(drv); 105 } else 106 error = -EINVAL; 107 return error; 108 } 109 110 111 /** 112 * driver_remove_file - remove sysfs file for driver. 113 * @drv: driver. 114 * @attr: driver attribute descriptor. 115 */ 116 117 void driver_remove_file(struct device_driver * drv, struct driver_attribute * attr) 118 { 119 if (get_driver(drv)) { 120 sysfs_remove_file(&drv->kobj, &attr->attr); 121 put_driver(drv); 122 } 123 } 124 125 126 /** 127 * get_driver - increment driver reference count. 128 * @drv: driver. 129 */ 130 struct device_driver * get_driver(struct device_driver * drv) 131 { 132 return drv ? to_drv(kobject_get(&drv->kobj)) : NULL; 133 } 134 135 136 /** 137 * put_driver - decrement driver's refcount. 138 * @drv: driver. 139 */ 140 void put_driver(struct device_driver * drv) 141 { 142 kobject_put(&drv->kobj); 143 } 144 145 146 /** 147 * driver_register - register driver with bus 148 * @drv: driver to register 149 * 150 * We pass off most of the work to the bus_add_driver() call, 151 * since most of the things we have to do deal with the bus 152 * structures. 153 * 154 * The one interesting aspect is that we setup @drv->unloaded 155 * as a completion that gets complete when the driver reference 156 * count reaches 0. 157 */ 158 int driver_register(struct device_driver * drv) 159 { 160 klist_init(&drv->klist_devices); 161 init_completion(&drv->unloaded); 162 return bus_add_driver(drv); 163 } 164 165 166 /** 167 * driver_unregister - remove driver from system. 168 * @drv: driver. 169 * 170 * Again, we pass off most of the work to the bus-level call. 171 * 172 * Though, once that is done, we wait until @drv->unloaded is completed. 173 * This will block until the driver refcount reaches 0, and it is 174 * released. Only modular drivers will call this function, and we 175 * have to guarantee that it won't complete, letting the driver 176 * unload until all references are gone. 177 */ 178 179 void driver_unregister(struct device_driver * drv) 180 { 181 bus_remove_driver(drv); 182 wait_for_completion(&drv->unloaded); 183 } 184 185 /** 186 * driver_find - locate driver on a bus by its name. 187 * @name: name of the driver. 188 * @bus: bus to scan for the driver. 189 * 190 * Call kset_find_obj() to iterate over list of drivers on 191 * a bus to find driver by name. Return driver if found. 192 * 193 * Note that kset_find_obj increments driver's reference count. 194 */ 195 struct device_driver *driver_find(const char *name, struct bus_type *bus) 196 { 197 struct kobject *k = kset_find_obj(&bus->drivers, name); 198 if (k) 199 return to_drv(k); 200 return NULL; 201 } 202 203 EXPORT_SYMBOL_GPL(driver_register); 204 EXPORT_SYMBOL_GPL(driver_unregister); 205 EXPORT_SYMBOL_GPL(get_driver); 206 EXPORT_SYMBOL_GPL(put_driver); 207 EXPORT_SYMBOL_GPL(driver_find); 208 209 EXPORT_SYMBOL_GPL(driver_create_file); 210 EXPORT_SYMBOL_GPL(driver_remove_file); 211