drivers/base/driver.c

   1 /*
   2  * driver.c - centralized device driver management
   3  *
   4  * Copyright (c) 2002-3 Patrick Mochel
   5  * Copyright (c) 2002-3 Open Source Development Labs
   6  *
   7  * This file is released under the GPLv2
   8  *
   9  */
  10
  11 #include <linux/config.h>
  12 #include <linux/device.h>
  13 #include <linux/module.h>
  14 #include <linux/errno.h>
  15 #include <linux/string.h>
  16 #include "base.h"
  17
  18 #define to_dev(node) container_of(node, struct device, driver_list)
  19 #define to_drv(obj) container_of(obj, struct device_driver, kobj)
  20
  21
  22 static struct device * next_device(struct klist_iter * i)
  23 {
  24         struct klist_node * n = klist_next(i);
  25         return n ? container_of(n, struct device, knode_driver) : NULL;
  26 }
  27
  28 /**
  29  *      driver_for_each_device - Iterator for devices bound to a driver.
  30  *      @drv:   Driver we're iterating.
  31  *      @start: Device to begin with
  32  *      @data:  Data to pass to the callback.
  33  *      @fn:    Function to call for each device.
  34  *
  35  *      Iterate over the @drv's list of devices calling @fn for each one.
  36  */
  37
  38 int driver_for_each_device(struct device_driver * drv, struct device * start,
  39                            void * data, int (*fn)(struct device *, void *))
  40 {
  41         struct klist_iter i;
  42         struct device * dev;
  43         int error = 0;
  44
  45         if (!drv)
  46                 return -EINVAL;
  47
  48         klist_iter_init_node(&drv->klist_devices, &i,
  49                              start ? &start->knode_driver : NULL);
  50         while ((dev = next_device(&i)) && !error)
  51                 error = fn(dev, data);
  52         klist_iter_exit(&i);
  53         return error;
  54 }
  55
  56 EXPORT_SYMBOL_GPL(driver_for_each_device);
  57
  58
  59 /**
  60  * driver_find_device - device iterator for locating a particular device.
  61  * @drv: The device's driver
  62  * @start: Device to begin with
  63  * @data: Data to pass to match function
  64  * @match: Callback function to check device
  65  *
  66  * This is similar to the driver_for_each_device() function above, but
  67  * it returns a reference to a device that is 'found' for later use, as
  68  * determined by the @match callback.
  69  *
  70  * The callback should return 0 if the device doesn't match and non-zero
  71  * if it does.  If the callback returns non-zero, this function will
  72  * return to the caller and not iterate over any more devices.
  73  */
  74 struct device * driver_find_device(struct device_driver *drv,
  75                                    struct device * start, void * data,
  76                                    int (*match)(struct device *, void *))
  77 {
  78         struct klist_iter i;
  79         struct device *dev;
  80
  81         if (!drv)
  82                 return NULL;
  83
  84         klist_iter_init_node(&drv->klist_devices, &i,
  85                              (start ? &start->knode_driver : NULL));
  86         while ((dev = next_device(&i)))
  87                 if (match(dev, data) && get_device(dev))
  88                         break;
  89         klist_iter_exit(&i);
  90         return dev;
  91 }
  92 EXPORT_SYMBOL_GPL(driver_find_device);
  93
  94 /**
  95  *      driver_create_file - create sysfs file for driver.
  96  *      @drv:   driver.
  97  *      @attr:  driver attribute descriptor.
  98  */
  99
 100 int driver_create_file(struct device_driver * drv, struct driver_attribute * attr)
 101 {
 102         int error;
 103         if (get_driver(drv)) {
 104                 error = sysfs_create_file(&drv->kobj, &attr->attr);
 105                 put_driver(drv);
 106         } else
 107                 error = -EINVAL;
 108         return error;
 109 }
 110
 111
 112 /**
 113  *      driver_remove_file - remove sysfs file for driver.
 114  *      @drv:   driver.
 115  *      @attr:  driver attribute descriptor.
 116  */
 117
 118 void driver_remove_file(struct device_driver * drv, struct driver_attribute * attr)
 119 {
 120         if (get_driver(drv)) {
 121                 sysfs_remove_file(&drv->kobj, &attr->attr);
 122                 put_driver(drv);
 123         }
 124 }
 125
 126
 127 /**
 128  *      get_driver - increment driver reference count.
 129  *      @drv:   driver.
 130  */
 131 struct device_driver * get_driver(struct device_driver * drv)
 132 {
 133         return drv ? to_drv(kobject_get(&drv->kobj)) : NULL;
 134 }
 135
 136
 137 /**
 138  *      put_driver - decrement driver's refcount.
 139  *      @drv:   driver.
 140  */
 141 void put_driver(struct device_driver * drv)
 142 {
 143         kobject_put(&drv->kobj);
 144 }
 145
 146 static void klist_devices_get(struct klist_node *n)
 147 {
 148         struct device *dev = container_of(n, struct device, knode_driver);
 149
 150         get_device(dev);
 151 }
 152
 153 static void klist_devices_put(struct klist_node *n)
 154 {
 155         struct device *dev = container_of(n, struct device, knode_driver);
 156
 157         put_device(dev);
 158 }
 159
 160 /**
 161  *      driver_register - register driver with bus
 162  *      @drv:   driver to register
 163  *
 164  *      We pass off most of the work to the bus_add_driver() call,
 165  *      since most of the things we have to do deal with the bus
 166  *      structures.
 167  *
 168  *      The one interesting aspect is that we setup @drv->unloaded
 169  *      as a completion that gets complete when the driver reference
 170  *      count reaches 0.
 171  */
 172 int driver_register(struct device_driver * drv)
 173 {
 174         klist_init(&drv->klist_devices, klist_devices_get, klist_devices_put);
 175         init_completion(&drv->unloaded);
 176         return bus_add_driver(drv);
 177 }
 178
 179
 180 /**
 181  *      driver_unregister - remove driver from system.
 182  *      @drv:   driver.
 183  *
 184  *      Again, we pass off most of the work to the bus-level call.
 185  *
 186  *      Though, once that is done, we wait until @drv->unloaded is completed.
 187  *      This will block until the driver refcount reaches 0, and it is
 188  *      released. Only modular drivers will call this function, and we
 189  *      have to guarantee that it won't complete, letting the driver
 190  *      unload until all references are gone.
 191  */
 192
 193 void driver_unregister(struct device_driver * drv)
 194 {
 195         bus_remove_driver(drv);
 196         wait_for_completion(&drv->unloaded);
 197 }
 198
 199 /**
 200  *      driver_find - locate driver on a bus by its name.
 201  *      @name:  name of the driver.
 202  *      @bus:   bus to scan for the driver.
 203  *
 204  *      Call kset_find_obj() to iterate over list of drivers on
 205  *      a bus to find driver by name. Return driver if found.
 206  *
 207  *      Note that kset_find_obj increments driver's reference count.
 208  */
 209 struct device_driver *driver_find(const char *name, struct bus_type *bus)
 210 {
 211         struct kobject *k = kset_find_obj(&bus->drivers, name);
 212         if (k)
 213                 return to_drv(k);
 214         return NULL;
 215 }
 216
 217 EXPORT_SYMBOL_GPL(driver_register);
 218 EXPORT_SYMBOL_GPL(driver_unregister);
 219 EXPORT_SYMBOL_GPL(get_driver);
 220 EXPORT_SYMBOL_GPL(put_driver);
 221 EXPORT_SYMBOL_GPL(driver_find);
 222
 223 EXPORT_SYMBOL_GPL(driver_create_file);
 224 EXPORT_SYMBOL_GPL(driver_remove_file);