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