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_create_file - create sysfs file for driver.
  60  *      @drv:   driver.
  61  *      @attr:  driver attribute descriptor.
  62  */
  63
  64 int driver_create_file(struct device_driver * drv, struct driver_attribute * attr)
  65 {
  66         int error;
  67         if (get_driver(drv)) {
  68                 error = sysfs_create_file(&drv->kobj, &attr->attr);
  69                 put_driver(drv);
  70         } else
  71                 error = -EINVAL;
  72         return error;
  73 }
  74
  75
  76 /**
  77  *      driver_remove_file - remove sysfs file for driver.
  78  *      @drv:   driver.
  79  *      @attr:  driver attribute descriptor.
  80  */
  81
  82 void driver_remove_file(struct device_driver * drv, struct driver_attribute * attr)
  83 {
  84         if (get_driver(drv)) {
  85                 sysfs_remove_file(&drv->kobj, &attr->attr);
  86                 put_driver(drv);
  87         }
  88 }
  89
  90
  91 /**
  92  *      get_driver - increment driver reference count.
  93  *      @drv:   driver.
  94  */
  95 struct device_driver * get_driver(struct device_driver * drv)
  96 {
  97         return drv ? to_drv(kobject_get(&drv->kobj)) : NULL;
  98 }
  99
 100
 101 /**
 102  *      put_driver - decrement driver's refcount.
 103  *      @drv:   driver.
 104  */
 105 void put_driver(struct device_driver * drv)
 106 {
 107         kobject_put(&drv->kobj);
 108 }
 109
 110
 111 /**
 112  *      driver_register - register driver with bus
 113  *      @drv:   driver to register
 114  *
 115  *      We pass off most of the work to the bus_add_driver() call,
 116  *      since most of the things we have to do deal with the bus
 117  *      structures.
 118  *
 119  *      The one interesting aspect is that we setup @drv->unloaded
 120  *      as a completion that gets complete when the driver reference
 121  *      count reaches 0.
 122  */
 123 int driver_register(struct device_driver * drv)
 124 {
 125         klist_init(&drv->klist_devices);
 126         init_completion(&drv->unloaded);
 127         return bus_add_driver(drv);
 128 }
 129
 130
 131 /**
 132  *      driver_unregister - remove driver from system.
 133  *      @drv:   driver.
 134  *
 135  *      Again, we pass off most of the work to the bus-level call.
 136  *
 137  *      Though, once that is done, we wait until @drv->unloaded is completed.
 138  *      This will block until the driver refcount reaches 0, and it is
 139  *      released. Only modular drivers will call this function, and we
 140  *      have to guarantee that it won't complete, letting the driver
 141  *      unload until all references are gone.
 142  */
 143
 144 void driver_unregister(struct device_driver * drv)
 145 {
 146         bus_remove_driver(drv);
 147         wait_for_completion(&drv->unloaded);
 148 }
 149
 150 /**
 151  *      driver_find - locate driver on a bus by its name.
 152  *      @name:  name of the driver.
 153  *      @bus:   bus to scan for the driver.
 154  *
 155  *      Call kset_find_obj() to iterate over list of drivers on
 156  *      a bus to find driver by name. Return driver if found.
 157  *
 158  *      Note that kset_find_obj increments driver's reference count.
 159  */
 160 struct device_driver *driver_find(const char *name, struct bus_type *bus)
 161 {
 162         struct kobject *k = kset_find_obj(&bus->drivers, name);
 163         if (k)
 164                 return to_drv(k);
 165         return NULL;
 166 }
 167
 168 EXPORT_SYMBOL_GPL(driver_register);
 169 EXPORT_SYMBOL_GPL(driver_unregister);
 170 EXPORT_SYMBOL_GPL(get_driver);
 171 EXPORT_SYMBOL_GPL(put_driver);
 172 EXPORT_SYMBOL_GPL(driver_find);
 173
 174 EXPORT_SYMBOL_GPL(driver_create_file);
 175 EXPORT_SYMBOL_GPL(driver_remove_file);