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 void device_bind_driver(struct device * dev)
  40 {
  41         pr_debug("bound device '%s' to driver '%s'\n",
  42                  dev->bus_id, dev->driver->name);
  43         klist_add_tail(&dev->driver->klist_devices, &dev->knode_driver);
  44         sysfs_create_link(&dev->driver->kobj, &dev->kobj,
  45                           kobject_name(&dev->kobj));
  46         sysfs_create_link(&dev->kobj, &dev->driver->kobj, "driver");
  47 }
  48
  49 /**
  50  *      driver_probe_device - attempt to bind device & driver.
  51  *      @drv:   driver.
  52  *      @dev:   device.
  53  *
  54  *      First, we call the bus's match function, if one present, which
  55  *      should compare the device IDs the driver supports with the
  56  *      device IDs of the device. Note we don't do this ourselves
  57  *      because we don't know the format of the ID structures, nor what
  58  *      is to be considered a match and what is not.
  59  *
  60  *      If we find a match, we call @drv->probe(@dev) if it exists, and
  61  *      call device_bind_driver() above.
  62  */
  63 int driver_probe_device(struct device_driver * drv, struct device * dev)
  64 {
  65         int error = 0;
  66
  67         if (drv->bus->match && !drv->bus->match(dev, drv))
  68                 return -ENODEV;
  69
  70         down(&dev->sem);
  71         dev->driver = drv;
  72         if (drv->probe) {
  73                 error = drv->probe(dev);
  74                 if (error) {
  75                         dev->driver = NULL;
  76                         up(&dev->sem);
  77                         return error;
  78                 }
  79         }
  80         up(&dev->sem);
  81         device_bind_driver(dev);
  82         return 0;
  83 }
  84
  85 static int __device_attach(struct device_driver * drv, void * data)
  86 {
  87         struct device * dev = data;
  88         int error;
  89
  90         error = driver_probe_device(drv, dev);
  91
  92         if (error == -ENODEV && error == -ENXIO) {
  93                 /* Driver matched, but didn't support device
  94                  * or device not found.
  95                  * Not an error; keep going.
  96                  */
  97                 error = 0;
  98         } else {
  99                 /* driver matched but the probe failed */
 100                 printk(KERN_WARNING
 101                        "%s: probe of %s failed with error %d\n",
 102                        drv->name, dev->bus_id, error);
 103         }
 104         return 0;
 105 }
 106
 107 /**
 108  *      device_attach - try to attach device to a driver.
 109  *      @dev:   device.
 110  *
 111  *      Walk the list of drivers that the bus has and call
 112  *      driver_probe_device() for each pair. If a compatible
 113  *      pair is found, break out and return.
 114  */
 115 int device_attach(struct device * dev)
 116 {
 117         if (dev->driver) {
 118                 device_bind_driver(dev);
 119                 return 1;
 120         }
 121
 122         return bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
 123 }
 124
 125 static int __driver_attach(struct device * dev, void * data)
 126 {
 127         struct device_driver * drv = data;
 128         int error = 0;
 129
 130         if (!dev->driver) {
 131                 error = driver_probe_device(drv, dev);
 132                 if (error) {
 133                         if (error != -ENODEV) {
 134                                 /* driver matched but the probe failed */
 135                                 printk(KERN_WARNING
 136                                        "%s: probe of %s failed with error %d\n",
 137                                        drv->name, dev->bus_id, error);
 138                         } else
 139                                 error = 0;
 140                 }
 141         }
 142         return 0;
 143 }
 144
 145 /**
 146  *      driver_attach - try to bind driver to devices.
 147  *      @drv:   driver.
 148  *
 149  *      Walk the list of devices that the bus has on it and try to
 150  *      match the driver with each one.  If driver_probe_device()
 151  *      returns 0 and the @dev->driver is set, we've found a
 152  *      compatible pair.
 153  *
 154  *      Note that we ignore the -ENODEV error from driver_probe_device(),
 155  *      since it's perfectly valid for a driver not to bind to any devices.
 156  */
 157 void driver_attach(struct device_driver * drv)
 158 {
 159         bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 160 }
 161
 162 /**
 163  *      device_release_driver - manually detach device from driver.
 164  *      @dev:   device.
 165  *
 166  *      Manually detach device from driver.
 167  *      Note that this is called without incrementing the bus
 168  *      reference count nor taking the bus's rwsem. Be sure that
 169  *      those are accounted for before calling this function.
 170  */
 171 void device_release_driver(struct device * dev)
 172 {
 173         struct device_driver * drv = dev->driver;
 174
 175         if (!drv)
 176                 return;
 177
 178         sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
 179         sysfs_remove_link(&dev->kobj, "driver");
 180         klist_del(&dev->knode_driver);
 181
 182         down(&dev->sem);
 183         if (drv->remove)
 184                 drv->remove(dev);
 185         dev->driver = NULL;
 186         up(&dev->sem);
 187 }
 188
 189 static int __remove_driver(struct device * dev, void * unused)
 190 {
 191         device_release_driver(dev);
 192         return 0;
 193 }
 194
 195 /**
 196  * driver_detach - detach driver from all devices it controls.
 197  * @drv: driver.
 198  */
 199 void driver_detach(struct device_driver * drv)
 200 {
 201         driver_for_each_device(drv, NULL, NULL, __remove_driver);
 202 }
 203
 204
 205 EXPORT_SYMBOL_GPL(driver_probe_device);
 206 EXPORT_SYMBOL_GPL(device_bind_driver);
 207 EXPORT_SYMBOL_GPL(device_release_driver);
 208 EXPORT_SYMBOL_GPL(device_attach);
 209 EXPORT_SYMBOL_GPL(driver_attach);
 210