drivers/base/dd.c

   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