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  *      driver_create_file - create sysfs file for driver.
  23  *      @drv:   driver.
  24  *      @attr:  driver attribute descriptor.
  25  */
  26
  27 int driver_create_file(struct device_driver * drv, struct driver_attribute * attr)
  28 {
  29         int error;
  30         if (get_driver(drv)) {
  31                 error = sysfs_create_file(&drv->kobj, &attr->attr);
  32                 put_driver(drv);
  33         } else
  34                 error = -EINVAL;
  35         return error;
  36 }
  37
  38
  39 /**
  40  *      driver_remove_file - remove sysfs file for driver.
  41  *      @drv:   driver.
  42  *      @attr:  driver attribute descriptor.
  43  */
  44
  45 void driver_remove_file(struct device_driver * drv, struct driver_attribute * attr)
  46 {
  47         if (get_driver(drv)) {
  48                 sysfs_remove_file(&drv->kobj, &attr->attr);
  49                 put_driver(drv);
  50         }
  51 }
  52
  53
  54 /**
  55  *      get_driver - increment driver reference count.
  56  *      @drv:   driver.
  57  */
  58 struct device_driver * get_driver(struct device_driver * drv)
  59 {
  60         return drv ? to_drv(kobject_get(&drv->kobj)) : NULL;
  61 }
  62
  63
  64 /**
  65  *      put_driver - decrement driver's refcount.
  66  *      @drv:   driver.
  67  */
  68 void put_driver(struct device_driver * drv)
  69 {
  70         kobject_put(&drv->kobj);
  71 }
  72
  73
  74 /**
  75  *      driver_register - register driver with bus
  76  *      @drv:   driver to register
  77  *
  78  *      We pass off most of the work to the bus_add_driver() call,
  79  *      since most of the things we have to do deal with the bus
  80  *      structures.
  81  *
  82  *      The one interesting aspect is that we initialize @drv->unload_sem
  83  *      to a locked state here. It will be unlocked when the driver
  84  *      reference count reaches 0.
  85  */
  86 int driver_register(struct device_driver * drv)
  87 {
  88         INIT_LIST_HEAD(&drv->devices);
  89         init_MUTEX_LOCKED(&drv->unload_sem);
  90         return bus_add_driver(drv);
  91 }
  92
  93
  94 /**
  95  *      driver_unregister - remove driver from system.
  96  *      @drv:   driver.
  97  *
  98  *      Again, we pass off most of the work to the bus-level call.
  99  *
 100  *      Though, once that is done, we attempt to take @drv->unload_sem.
 101  *      This will block until the driver refcount reaches 0, and it is
 102  *      released. Only modular drivers will call this function, and we
 103  *      have to guarantee that it won't complete, letting the driver
 104  *      unload until all references are gone.
 105  */
 106
 107 void driver_unregister(struct device_driver * drv)
 108 {
 109         bus_remove_driver(drv);
 110         down(&drv->unload_sem);
 111         up(&drv->unload_sem);
 112 }
 113
 114 /**
 115  *      driver_find - locate driver on a bus by its name.
 116  *      @name:  name of the driver.
 117  *      @bus:   bus to scan for the driver.
 118  *
 119  *      Call kset_find_obj() to iterate over list of drivers on
 120  *      a bus to find driver by name. Return driver if found.
 121  *
 122  *      Note that kset_find_obj increments driver's reference count.
 123  */
 124 struct device_driver *driver_find(const char *name, struct bus_type *bus)
 125 {
 126         struct kobject *k = kset_find_obj(&bus->drivers, name);
 127         if (k)
 128                 return to_drv(k);
 129         return NULL;
 130 }
 131
 132 EXPORT_SYMBOL(driver_register);
 133 EXPORT_SYMBOL(driver_unregister);
 134 EXPORT_SYMBOL(get_driver);
 135 EXPORT_SYMBOL(put_driver);
 136 EXPORT_SYMBOL(driver_find);
 137
 138 EXPORT_SYMBOL(driver_create_file);
 139 EXPORT_SYMBOL(driver_remove_file);