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 int device_bind_driver(struct device *dev)
  42 {
  43         int ret;
  44
  45         if (klist_node_attached(&dev->knode_driver)) {
  46                 printk(KERN_WARNING "%s: device %s already bound\n",
  47                         __FUNCTION__, kobject_name(&dev->kobj));
  48                 return 0;
  49         }
  50
  51         pr_debug("bound device '%s' to driver '%s'\n",
  52                  dev->bus_id, dev->driver->name);
  53         klist_add_tail(&dev->knode_driver, &dev->driver->klist_devices);
  54         ret = sysfs_create_link(&dev->driver->kobj, &dev->kobj,
  55                           kobject_name(&dev->kobj));
  56         if (ret == 0) {
  57                 ret = sysfs_create_link(&dev->kobj, &dev->driver->kobj,
  58                                         "driver");
  59                 if (ret)
  60                         sysfs_remove_link(&dev->driver->kobj,
  61                                         kobject_name(&dev->kobj));
  62         }
  63         return ret;
  64 }
  65
  66 /**
  67  *      driver_probe_device - attempt to bind device & driver.
  68  *      @drv:   driver.
  69  *      @dev:   device.
  70  *
  71  *      First, we call the bus's match function, if one present, which
  72  *      should compare the device IDs the driver supports with the
  73  *      device IDs of the device. Note we don't do this ourselves
  74  *      because we don't know the format of the ID structures, nor what
  75  *      is to be considered a match and what is not.
  76  *
  77  *      This function returns 1 if a match is found, an error if one
  78  *      occurs (that is not -ENODEV or -ENXIO), and 0 otherwise.
  79  *
  80  *      This function must be called with @dev->sem held.  When called
  81  *      for a USB interface, @dev->parent->sem must be held as well.
  82  */
  83 int driver_probe_device(struct device_driver * drv, struct device * dev)
  84 {
  85         int ret = 0;
  86
  87         if (drv->bus->match && !drv->bus->match(dev, drv))
  88                 goto Done;
  89
  90         pr_debug("%s: Matched Device %s with Driver %s\n",
  91                  drv->bus->name, dev->bus_id, drv->name);
  92         dev->driver = drv;
  93         if (dev->bus->probe) {
  94                 ret = dev->bus->probe(dev);
  95                 if (ret) {
  96                         dev->driver = NULL;
  97                         goto ProbeFailed;
  98                 }
  99         } else if (drv->probe) {
 100                 ret = drv->probe(dev);
 101                 if (ret) {
 102                         dev->driver = NULL;
 103                         goto ProbeFailed;
 104                 }
 105         }
 106         if (device_bind_driver(dev)) {
 107                 printk(KERN_ERR "%s: device_bind_driver(%s) failed\n",
 108                         __FUNCTION__, dev->bus_id);
 109                 /* How does undo a ->probe?  We're screwed. */
 110         }
 111         ret = 1;
 112         pr_debug("%s: Bound Device %s to Driver %s\n",
 113                  drv->bus->name, dev->bus_id, drv->name);
 114         goto Done;
 115
 116  ProbeFailed:
 117         if (ret == -ENODEV || ret == -ENXIO) {
 118                 /* Driver matched, but didn't support device
 119                  * or device not found.
 120                  * Not an error; keep going.
 121                  */
 122                 ret = 0;
 123         } else {
 124                 /* driver matched but the probe failed */
 125                 printk(KERN_WARNING
 126                        "%s: probe of %s failed with error %d\n",
 127                        drv->name, dev->bus_id, ret);
 128         }
 129  Done:
 130         return ret;
 131 }
 132
 133 static int __device_attach(struct device_driver * drv, void * data)
 134 {
 135         struct device * dev = data;
 136         return driver_probe_device(drv, dev);
 137 }
 138
 139 /**
 140  *      device_attach - try to attach device to a driver.
 141  *      @dev:   device.
 142  *
 143  *      Walk the list of drivers that the bus has and call
 144  *      driver_probe_device() for each pair. If a compatible
 145  *      pair is found, break out and return.
 146  *
 147  *      Returns 1 if the device was bound to a driver;
 148  *      0 if no matching device was found; error code otherwise.
 149  *
 150  *      When called for a USB interface, @dev->parent->sem must be held.
 151  */
 152 int device_attach(struct device * dev)
 153 {
 154         int ret = 0;
 155
 156         down(&dev->sem);
 157         if (dev->driver) {
 158                 ret = device_bind_driver(dev);
 159                 if (ret == 0)
 160                         ret = 1;
 161         } else
 162                 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
 163         up(&dev->sem);
 164         return ret;
 165 }
 166
 167 static int __driver_attach(struct device * dev, void * data)
 168 {
 169         struct device_driver * drv = data;
 170
 171         /*
 172          * Lock device and try to bind to it. We drop the error
 173          * here and always return 0, because we need to keep trying
 174          * to bind to devices and some drivers will return an error
 175          * simply if it didn't support the device.
 176          *
 177          * driver_probe_device() will spit a warning if there
 178          * is an error.
 179          */
 180
 181         if (dev->parent)        /* Needed for USB */
 182                 down(&dev->parent->sem);
 183         down(&dev->sem);
 184         if (!dev->driver)
 185                 driver_probe_device(drv, dev);
 186         up(&dev->sem);
 187         if (dev->parent)
 188                 up(&dev->parent->sem);
 189
 190         return 0;
 191 }
 192
 193 /**
 194  *      driver_attach - try to bind driver to devices.
 195  *      @drv:   driver.
 196  *
 197  *      Walk the list of devices that the bus has on it and try to
 198  *      match the driver with each one.  If driver_probe_device()
 199  *      returns 0 and the @dev->driver is set, we've found a
 200  *      compatible pair.
 201  */
 202 int driver_attach(struct device_driver * drv)
 203 {
 204         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 205 }
 206
 207 /**
 208  *      device_release_driver - manually detach device from driver.
 209  *      @dev:   device.
 210  *
 211  *      Manually detach device from driver.
 212  *
 213  *      __device_release_driver() must be called with @dev->sem held.
 214  *      When called for a USB interface, @dev->parent->sem must be held
 215  *      as well.
 216  */
 217
 218 static void __device_release_driver(struct device * dev)
 219 {
 220         struct device_driver * drv;
 221
 222         drv = dev->driver;
 223         if (drv) {
 224                 get_driver(drv);
 225                 sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
 226                 sysfs_remove_link(&dev->kobj, "driver");
 227                 klist_remove(&dev->knode_driver);
 228
 229                 if (dev->bus && dev->bus->remove)
 230                         dev->bus->remove(dev);
 231                 else if (drv->remove)
 232                         drv->remove(dev);
 233                 dev->driver = NULL;
 234                 put_driver(drv);
 235         }
 236 }
 237
 238 void device_release_driver(struct device * dev)
 239 {
 240         /*
 241          * If anyone calls device_release_driver() recursively from
 242          * within their ->remove callback for the same device, they
 243          * will deadlock right here.
 244          */
 245         down(&dev->sem);
 246         __device_release_driver(dev);
 247         up(&dev->sem);
 248 }
 249
 250
 251 /**
 252  * driver_detach - detach driver from all devices it controls.
 253  * @drv: driver.
 254  */
 255 void driver_detach(struct device_driver * drv)
 256 {
 257         struct device * dev;
 258
 259         for (;;) {
 260                 spin_lock(&drv->klist_devices.k_lock);
 261                 if (list_empty(&drv->klist_devices.k_list)) {
 262                         spin_unlock(&drv->klist_devices.k_lock);
 263                         break;
 264                 }
 265                 dev = list_entry(drv->klist_devices.k_list.prev,
 266                                 struct device, knode_driver.n_node);
 267                 get_device(dev);
 268                 spin_unlock(&drv->klist_devices.k_lock);
 269
 270                 if (dev->parent)        /* Needed for USB */
 271                         down(&dev->parent->sem);
 272                 down(&dev->sem);
 273                 if (dev->driver == drv)
 274                         __device_release_driver(dev);
 275                 up(&dev->sem);
 276                 if (dev->parent)
 277                         up(&dev->parent->sem);
 278                 put_device(dev);
 279         }
 280 }
 281
 282
 283 EXPORT_SYMBOL_GPL(device_bind_driver);
 284 EXPORT_SYMBOL_GPL(device_release_driver);
 285 EXPORT_SYMBOL_GPL(device_attach);
 286 EXPORT_SYMBOL_GPL(driver_attach);
 287