1 /* 2 * drivers/base/dd.c - The core device/driver interactions. 3 * 4 * This file contains the (sometimes tricky) code that controls the 5 * interactions between devices and drivers, which primarily includes 6 * driver binding and unbinding. 7 * 8 * All of this code used to exist in drivers/base/bus.c, but was 9 * relocated to here in the name of compartmentalization (since it wasn't 10 * strictly code just for the 'struct bus_type'. 11 * 12 * Copyright (c) 2002-5 Patrick Mochel 13 * Copyright (c) 2002-3 Open Source Development Labs 14 * 15 * This file is released under the GPLv2 16 */ 17 18 #include <linux/device.h> 19 #include <linux/module.h> 20 21 #include "base.h" 22 #include "power/power.h" 23 24 #define to_drv(node) container_of(node, struct device_driver, kobj.entry) 25 26 27 /** 28 * device_bind_driver - bind a driver to one device. 29 * @dev: device. 30 * 31 * Allow manual attachment of a driver to a device. 32 * Caller must have already set @dev->driver. 33 * 34 * Note that this does not modify the bus reference count 35 * nor take the bus's rwsem. Please verify those are accounted 36 * for before calling this. (It is ok to call with no other effort 37 * from a driver's probe() method.) 38 * 39 * This function must be called with @dev->sem held. 40 */ 41 void device_bind_driver(struct device * dev) 42 { 43 if (klist_node_attached(&dev->knode_driver)) 44 return; 45 46 pr_debug("bound device '%s' to driver '%s'\n", 47 dev->bus_id, dev->driver->name); 48 klist_add_tail(&dev->knode_driver, &dev->driver->klist_devices); 49 sysfs_create_link(&dev->driver->kobj, &dev->kobj, 50 kobject_name(&dev->kobj)); 51 sysfs_create_link(&dev->kobj, &dev->driver->kobj, "driver"); 52 } 53 54 /** 55 * driver_probe_device - attempt to bind device & driver. 56 * @drv: driver. 57 * @dev: device. 58 * 59 * First, we call the bus's match function, if one present, which 60 * should compare the device IDs the driver supports with the 61 * device IDs of the device. Note we don't do this ourselves 62 * because we don't know the format of the ID structures, nor what 63 * is to be considered a match and what is not. 64 * 65 * This function returns 1 if a match is found, an error if one 66 * occurs (that is not -ENODEV or -ENXIO), and 0 otherwise. 67 * 68 * This function must be called with @dev->sem held. 69 */ 70 int driver_probe_device(struct device_driver * drv, struct device * dev) 71 { 72 int ret = 0; 73 74 if (drv->bus->match && !drv->bus->match(dev, drv)) 75 goto Done; 76 77 pr_debug("%s: Matched Device %s with Driver %s\n", 78 drv->bus->name, dev->bus_id, drv->name); 79 dev->driver = drv; 80 if (drv->probe) { 81 ret = drv->probe(dev); 82 if (ret) { 83 dev->driver = NULL; 84 goto ProbeFailed; 85 } 86 } 87 device_bind_driver(dev); 88 ret = 1; 89 pr_debug("%s: Bound Device %s to Driver %s\n", 90 drv->bus->name, dev->bus_id, drv->name); 91 goto Done; 92 93 ProbeFailed: 94 if (ret == -ENODEV || ret == -ENXIO) { 95 /* Driver matched, but didn't support device 96 * or device not found. 97 * Not an error; keep going. 98 */ 99 ret = 0; 100 } else { 101 /* driver matched but the probe failed */ 102 printk(KERN_WARNING 103 "%s: probe of %s failed with error %d\n", 104 drv->name, dev->bus_id, ret); 105 } 106 Done: 107 return ret; 108 } 109 110 static int __device_attach(struct device_driver * drv, void * data) 111 { 112 struct device * dev = data; 113 return driver_probe_device(drv, dev); 114 } 115 116 /** 117 * device_attach - try to attach device to a driver. 118 * @dev: device. 119 * 120 * Walk the list of drivers that the bus has and call 121 * driver_probe_device() for each pair. If a compatible 122 * pair is found, break out and return. 123 * 124 * Returns 1 if the device was bound to a driver; 125 * 0 if no matching device was found; error code otherwise. 126 */ 127 int device_attach(struct device * dev) 128 { 129 int ret = 0; 130 131 down(&dev->sem); 132 if (dev->driver) { 133 device_bind_driver(dev); 134 ret = 1; 135 } else 136 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach); 137 up(&dev->sem); 138 return ret; 139 } 140 141 static int __driver_attach(struct device * dev, void * data) 142 { 143 struct device_driver * drv = data; 144 145 /* 146 * Lock device and try to bind to it. We drop the error 147 * here and always return 0, because we need to keep trying 148 * to bind to devices and some drivers will return an error 149 * simply if it didn't support the device. 150 * 151 * driver_probe_device() will spit a warning if there 152 * is an error. 153 */ 154 155 down(&dev->sem); 156 if (!dev->driver) 157 driver_probe_device(drv, dev); 158 up(&dev->sem); 159 160 return 0; 161 } 162 163 /** 164 * driver_attach - try to bind driver to devices. 165 * @drv: driver. 166 * 167 * Walk the list of devices that the bus has on it and try to 168 * match the driver with each one. If driver_probe_device() 169 * returns 0 and the @dev->driver is set, we've found a 170 * compatible pair. 171 */ 172 void driver_attach(struct device_driver * drv) 173 { 174 bus_for_each_dev(drv->bus, NULL, drv, __driver_attach); 175 } 176 177 /** 178 * device_release_driver - manually detach device from driver. 179 * @dev: device. 180 * 181 * Manually detach device from driver. 182 * 183 * __device_release_driver() must be called with @dev->sem held. 184 */ 185 186 static void __device_release_driver(struct device * dev) 187 { 188 struct device_driver * drv; 189 190 drv = dev->driver; 191 if (drv) { 192 get_driver(drv); 193 sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj)); 194 sysfs_remove_link(&dev->kobj, "driver"); 195 klist_remove(&dev->knode_driver); 196 197 if (drv->remove) 198 drv->remove(dev); 199 dev->driver = NULL; 200 put_driver(drv); 201 } 202 } 203 204 void device_release_driver(struct device * dev) 205 { 206 /* 207 * If anyone calls device_release_driver() recursively from 208 * within their ->remove callback for the same device, they 209 * will deadlock right here. 210 */ 211 down(&dev->sem); 212 __device_release_driver(dev); 213 up(&dev->sem); 214 } 215 216 217 /** 218 * driver_detach - detach driver from all devices it controls. 219 * @drv: driver. 220 */ 221 void driver_detach(struct device_driver * drv) 222 { 223 struct device * dev; 224 225 for (;;) { 226 spin_lock(&drv->klist_devices.k_lock); 227 if (list_empty(&drv->klist_devices.k_list)) { 228 spin_unlock(&drv->klist_devices.k_lock); 229 break; 230 } 231 dev = list_entry(drv->klist_devices.k_list.prev, 232 struct device, knode_driver.n_node); 233 get_device(dev); 234 spin_unlock(&drv->klist_devices.k_lock); 235 236 down(&dev->sem); 237 if (dev->driver == drv) 238 __device_release_driver(dev); 239 up(&dev->sem); 240 put_device(dev); 241 } 242 } 243 244 245 EXPORT_SYMBOL_GPL(device_bind_driver); 246 EXPORT_SYMBOL_GPL(device_release_driver); 247 EXPORT_SYMBOL_GPL(device_attach); 248 EXPORT_SYMBOL_GPL(driver_attach); 249 250