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.  When called
  69  *      for a USB interface, @dev->parent->sem must be held as well.
  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  *      When called for a USB interface, @dev->parent->sem must be held.
 129  */
 130 int device_attach(struct device * dev)
 131 {
 132         int ret = 0;
 133
 134         down(&dev->sem);
 135         if (dev->driver) {
 136                 device_bind_driver(dev);
 137                 ret = 1;
 138         } else
 139                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
 140         up(&dev->sem);
 141         return ret;
 142 }
 143
 144 static int __driver_attach(struct device * dev, void * data)
 145 {
 146         struct device_driver * drv = data;
 147
 148         /*
 149          * Lock device and try to bind to it. We drop the error
 150          * here and always return 0, because we need to keep trying
 151          * to bind to devices and some drivers will return an error
 152          * simply if it didn't support the device.
 153          *
 154          * driver_probe_device() will spit a warning if there
 155          * is an error.
 156          */
 157
 158         if (dev->parent)        /* Needed for USB */
 159                 down(&dev->parent->sem);
 160         down(&dev->sem);
 161         if (!dev->driver)
 162                 driver_probe_device(drv, dev);
 163         up(&dev->sem);
 164         if (dev->parent)
 165                 up(&dev->parent->sem);
 166
 167         return 0;
 168 }
 169
 170 /**
 171  *      driver_attach - try to bind driver to devices.
 172  *      @drv:   driver.
 173  *
 174  *      Walk the list of devices that the bus has on it and try to
 175  *      match the driver with each one.  If driver_probe_device()
 176  *      returns 0 and the @dev->driver is set, we've found a
 177  *      compatible pair.
 178  */
 179 void driver_attach(struct device_driver * drv)
 180 {
 181         bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 182 }
 183
 184 /**
 185  *      device_release_driver - manually detach device from driver.
 186  *      @dev:   device.
 187  *
 188  *      Manually detach device from driver.
 189  *
 190  *      __device_release_driver() must be called with @dev->sem held.
 191  *      When called for a USB interface, @dev->parent->sem must be held
 192  *      as well.
 193  */
 194
 195 static void __device_release_driver(struct device * dev)
 196 {
 197         struct device_driver * drv;
 198
 199         drv = dev->driver;
 200         if (drv) {
 201                 get_driver(drv);
 202                 sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
 203                 sysfs_remove_link(&dev->kobj, "driver");
 204                 klist_remove(&dev->knode_driver);
 205
 206                 if (drv->remove)
 207                         drv->remove(dev);
 208                 dev->driver = NULL;
 209                 put_driver(drv);
 210         }
 211 }
 212
 213 void device_release_driver(struct device * dev)
 214 {
 215         /*
 216          * If anyone calls device_release_driver() recursively from
 217          * within their ->remove callback for the same device, they
 218          * will deadlock right here.
 219          */
 220         down(&dev->sem);
 221         __device_release_driver(dev);
 222         up(&dev->sem);
 223 }
 224
 225
 226 /**
 227  * driver_detach - detach driver from all devices it controls.
 228  * @drv: driver.
 229  */
 230 void driver_detach(struct device_driver * drv)
 231 {
 232         struct device * dev;
 233
 234         for (;;) {
 235                 spin_lock(&drv->klist_devices.k_lock);
 236                 if (list_empty(&drv->klist_devices.k_list)) {
 237                         spin_unlock(&drv->klist_devices.k_lock);
 238                         break;
 239                 }
 240                 dev = list_entry(drv->klist_devices.k_list.prev,
 241                                 struct device, knode_driver.n_node);
 242                 get_device(dev);
 243                 spin_unlock(&drv->klist_devices.k_lock);
 244
 245                 if (dev->parent)        /* Needed for USB */
 246                         down(&dev->parent->sem);
 247                 down(&dev->sem);
 248                 if (dev->driver == drv)
 249                         __device_release_driver(dev);
 250                 up(&dev->sem);
 251                 if (dev->parent)
 252                         up(&dev->parent->sem);
 253                 put_device(dev);
 254         }
 255 }
 256
 257
 258 EXPORT_SYMBOL_GPL(device_bind_driver);
 259 EXPORT_SYMBOL_GPL(device_release_driver);
 260 EXPORT_SYMBOL_GPL(device_attach);
 261 EXPORT_SYMBOL_GPL(driver_attach);
 262