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   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 /**
  23  *      driver_for_each_device - Iterator for devices bound to a driver.
  24  *      @drv:   Driver we're iterating.
  25  *      @data:  Data to pass to the callback.
  26  *      @fn:    Function to call for each device.
  27  *
  28  *      Take the bus's rwsem and iterate over the @drv's list of devices,
  29  *      calling @fn for each one.
  30  */
  31
  32 int driver_for_each_device(struct device_driver * drv, struct device * start,
  33                            void * data, int (*fn)(struct device *, void *))
  34 {
  35         struct list_head * head;
  36         struct device * dev;
  37         int error = 0;
  38
  39         down_read(&drv->bus->subsys.rwsem);
  40         head = &drv->devices;
  41         dev = list_prepare_entry(start, head, driver_list);
  42         list_for_each_entry_continue(dev, head, driver_list) {
  43                 get_device(dev);
  44                 error = fn(dev, data);
  45                 put_device(dev);
  46                 if (error)
  47                         break;
  48         }
  49         up_read(&drv->bus->subsys.rwsem);
  50         return error;
  51 }
  52
  53 EXPORT_SYMBOL(driver_for_each_device);
  54
  55
  56 /**
  57  *      driver_create_file - create sysfs file for driver.
  58  *      @drv:   driver.
  59  *      @attr:  driver attribute descriptor.
  60  */
  61
  62 int driver_create_file(struct device_driver * drv, struct driver_attribute * attr)
  63 {
  64         int error;
  65         if (get_driver(drv)) {
  66                 error = sysfs_create_file(&drv->kobj, &attr->attr);
  67                 put_driver(drv);
  68         } else
  69                 error = -EINVAL;
  70         return error;
  71 }
  72
  73
  74 /**
  75  *      driver_remove_file - remove sysfs file for driver.
  76  *      @drv:   driver.
  77  *      @attr:  driver attribute descriptor.
  78  */
  79
  80 void driver_remove_file(struct device_driver * drv, struct driver_attribute * attr)
  81 {
  82         if (get_driver(drv)) {
  83                 sysfs_remove_file(&drv->kobj, &attr->attr);
  84                 put_driver(drv);
  85         }
  86 }
  87
  88
  89 /**
  90  *      get_driver - increment driver reference count.
  91  *      @drv:   driver.
  92  */
  93 struct device_driver * get_driver(struct device_driver * drv)
  94 {
  95         return drv ? to_drv(kobject_get(&drv->kobj)) : NULL;
  96 }
  97
  98
  99 /**
 100  *      put_driver - decrement driver's refcount.
 101  *      @drv:   driver.
 102  */
 103 void put_driver(struct device_driver * drv)
 104 {
 105         kobject_put(&drv->kobj);
 106 }
 107
 108
 109 /**
 110  *      driver_register - register driver with bus
 111  *      @drv:   driver to register
 112  *
 113  *      We pass off most of the work to the bus_add_driver() call,
 114  *      since most of the things we have to do deal with the bus
 115  *      structures.
 116  *
 117  *      The one interesting aspect is that we setup @drv->unloaded
 118  *      as a completion that gets complete when the driver reference
 119  *      count reaches 0.
 120  */
 121 int driver_register(struct device_driver * drv)
 122 {
 123         INIT_LIST_HEAD(&drv->devices);
 124         init_completion(&drv->unloaded);
 125         return bus_add_driver(drv);
 126 }
 127
 128
 129 /**
 130  *      driver_unregister - remove driver from system.
 131  *      @drv:   driver.
 132  *
 133  *      Again, we pass off most of the work to the bus-level call.
 134  *
 135  *      Though, once that is done, we wait until @drv->unloaded is completed.
 136  *      This will block until the driver refcount reaches 0, and it is
 137  *      released. Only modular drivers will call this function, and we
 138  *      have to guarantee that it won't complete, letting the driver
 139  *      unload until all references are gone.
 140  */
 141
 142 void driver_unregister(struct device_driver * drv)
 143 {
 144         bus_remove_driver(drv);
 145         wait_for_completion(&drv->unloaded);
 146 }
 147
 148 /**
 149  *      driver_find - locate driver on a bus by its name.
 150  *      @name:  name of the driver.
 151  *      @bus:   bus to scan for the driver.
 152  *
 153  *      Call kset_find_obj() to iterate over list of drivers on
 154  *      a bus to find driver by name. Return driver if found.
 155  *
 156  *      Note that kset_find_obj increments driver's reference count.
 157  */
 158 struct device_driver *driver_find(const char *name, struct bus_type *bus)
 159 {
 160         struct kobject *k = kset_find_obj(&bus->drivers, name);
 161         if (k)
 162                 return to_drv(k);
 163         return NULL;
 164 }
 165
 166 EXPORT_SYMBOL_GPL(driver_register);
 167 EXPORT_SYMBOL_GPL(driver_unregister);
 168 EXPORT_SYMBOL_GPL(get_driver);
 169 EXPORT_SYMBOL_GPL(put_driver);
 170 EXPORT_SYMBOL_GPL(driver_find);
 171
 172 EXPORT_SYMBOL_GPL(driver_create_file);
 173 EXPORT_SYMBOL_GPL(driver_remove_file);