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 * 66 * This function returns 1 if a match is found, an error if one 67 * occurs (that is not -ENODEV or -ENXIO), and 0 otherwise. 68 * 69 * This function must be called with @dev->sem held. 70 */ 71 int driver_probe_device(struct device_driver * drv, struct device * dev) 72 { 73 int ret = 0; 74 75 if (drv->bus->match && !drv->bus->match(dev, drv)) 76 goto Done; 77 78 pr_debug("%s: Matched Device %s with Driver %s\n", 79 drv->bus->name, dev->bus_id, drv->name); 80 dev->driver = drv; 81 if (drv->probe) { 82 ret = drv->probe(dev); 83 if (ret) { 84 dev->driver = NULL; 85 goto ProbeFailed; 86 } 87 } 88 device_bind_driver(dev); 89 ret = 1; 90 pr_debug("%s: Bound Device %s to Driver %s\n", 91 drv->bus->name, dev->bus_id, drv->name); 92 goto Done; 93 94 ProbeFailed: 95 if (ret == -ENODEV || ret == -ENXIO) { 96 /* Driver matched, but didn't support device 97 * or device not found. 98 * Not an error; keep going. 99 */ 100 ret = 0; 101 } else { 102 /* driver matched but the probe failed */ 103 printk(KERN_WARNING 104 "%s: probe of %s failed with error %d\n", 105 drv->name, dev->bus_id, ret); 106 } 107 Done: 108 return ret; 109 } 110 111 static int __device_attach(struct device_driver * drv, void * data) 112 { 113 struct device * dev = data; 114 return driver_probe_device(drv, dev); 115 } 116 117 /** 118 * device_attach - try to attach device to a driver. 119 * @dev: device. 120 * 121 * Walk the list of drivers that the bus has and call 122 * driver_probe_device() for each pair. If a compatible 123 * pair is found, break out and return. 124 * 125 * Returns 1 if the device was bound to a driver; 126 * 0 if no matching device was found; error code otherwise. 127 */ 128 int device_attach(struct device * dev) 129 { 130 int ret = 0; 131 132 down(&dev->sem); 133 if (dev->driver) { 134 device_bind_driver(dev); 135 ret = 1; 136 } else 137 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach); 138 up(&dev->sem); 139 return ret; 140 } 141 142 static int __driver_attach(struct device * dev, void * data) 143 { 144 struct device_driver * drv = data; 145 146 /* 147 * Lock device and try to bind to it. We drop the error 148 * here and always return 0, because we need to keep trying 149 * to bind to devices and some drivers will return an error 150 * simply if it didn't support the device. 151 * 152 * driver_probe_device() will spit a warning if there 153 * is an error. 154 */ 155 156 down(&dev->sem); 157 if (!dev->driver) 158 driver_probe_device(drv, dev); 159 up(&dev->sem); 160 161 162 return 0; 163 } 164 165 /** 166 * driver_attach - try to bind driver to devices. 167 * @drv: driver. 168 * 169 * Walk the list of devices that the bus has on it and try to 170 * match the driver with each one. If driver_probe_device() 171 * returns 0 and the @dev->driver is set, we've found a 172 * compatible pair. 173 */ 174 void driver_attach(struct device_driver * drv) 175 { 176 bus_for_each_dev(drv->bus, NULL, drv, __driver_attach); 177 } 178 179 /** 180 * device_release_driver - manually detach device from driver. 181 * @dev: device. 182 * 183 * Manually detach device from driver. 184 * 185 * __device_release_driver() must be called with @dev->sem held. 186 */ 187 188 static void __device_release_driver(struct device * dev) 189 { 190 struct device_driver * drv; 191 192 drv = dev->driver; 193 if (drv) { 194 get_driver(drv); 195 sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj)); 196 sysfs_remove_link(&dev->kobj, "driver"); 197 klist_remove(&dev->knode_driver); 198 199 if (drv->remove) 200 drv->remove(dev); 201 dev->driver = NULL; 202 put_driver(drv); 203 } 204 } 205 206 void device_release_driver(struct device * dev) 207 { 208 /* 209 * If anyone calls device_release_driver() recursively from 210 * within their ->remove callback for the same device, they 211 * will deadlock right here. 212 */ 213 down(&dev->sem); 214 __device_release_driver(dev); 215 up(&dev->sem); 216 } 217 218 219 /** 220 * driver_detach - detach driver from all devices it controls. 221 * @drv: driver. 222 */ 223 void driver_detach(struct device_driver * drv) 224 { 225 struct device * dev; 226 227 for (;;) { 228 spin_lock_irq(&drv->klist_devices.k_lock); 229 if (list_empty(&drv->klist_devices.k_list)) { 230 spin_unlock_irq(&drv->klist_devices.k_lock); 231 break; 232 } 233 dev = list_entry(drv->klist_devices.k_list.prev, 234 struct device, knode_driver.n_node); 235 get_device(dev); 236 spin_unlock_irq(&drv->klist_devices.k_lock); 237 238 down(&dev->sem); 239 if (dev->driver == drv) 240 __device_release_driver(dev); 241 up(&dev->sem); 242 put_device(dev); 243 } 244 } 245 246 247 EXPORT_SYMBOL_GPL(device_bind_driver); 248 EXPORT_SYMBOL_GPL(device_release_driver); 249 EXPORT_SYMBOL_GPL(device_attach); 250 EXPORT_SYMBOL_GPL(driver_attach); 251 252