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  * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
   7  * Copyright (c) 2007 Novell Inc.
   8  *
   9  * This file is released under the GPLv2
  10  *
  11  */
  12
  13 #include <linux/device.h>
  14 #include <linux/module.h>
  15 #include <linux/errno.h>
  16 #include <linux/slab.h>
  17 #include <linux/string.h>
  18 #include "base.h"
  19
  20 static struct device *next_device(struct klist_iter *i)
  21 {
  22         struct klist_node *n = klist_next(i);
  23         struct device *dev = NULL;
  24         struct device_private *dev_prv;
  25
  26         if (n) {
  27                 dev_prv = to_device_private_driver(n);
  28                 dev = dev_prv->device;
  29         }
  30         return dev;
  31 }
  32
  33 /**
  34  * driver_for_each_device - Iterator for devices bound to a driver.
  35  * @drv: Driver we're iterating.
  36  * @start: Device to begin with
  37  * @data: Data to pass to the callback.
  38  * @fn: Function to call for each device.
  39  *
  40  * Iterate over the @drv's list of devices calling @fn for each one.
  41  */
  42 int driver_for_each_device(struct device_driver *drv, struct device *start,
  43                            void *data, int (*fn)(struct device *, void *))
  44 {
  45         struct klist_iter i;
  46         struct device *dev;
  47         int error = 0;
  48
  49         if (!drv)
  50                 return -EINVAL;
  51
  52         klist_iter_init_node(&drv->p->klist_devices, &i,
  53                              start ? &start->p->knode_driver : NULL);
  54         while ((dev = next_device(&i)) && !error)
  55                 error = fn(dev, data);
  56         klist_iter_exit(&i);
  57         return error;
  58 }
  59 EXPORT_SYMBOL_GPL(driver_for_each_device);
  60
  61 /**
  62  * driver_find_device - device iterator for locating a particular device.
  63  * @drv: The device's driver
  64  * @start: Device to begin with
  65  * @data: Data to pass to match function
  66  * @match: Callback function to check device
  67  *
  68  * This is similar to the driver_for_each_device() function above, but
  69  * it returns a reference to a device that is 'found' for later use, as
  70  * determined by the @match callback.
  71  *
  72  * The callback should return 0 if the device doesn't match and non-zero
  73  * if it does.  If the callback returns non-zero, this function will
  74  * return to the caller and not iterate over any more devices.
  75  */
  76 struct device *driver_find_device(struct device_driver *drv,
  77                                   struct device *start, void *data,
  78                                   int (*match)(struct device *dev, void *data))
  79 {
  80         struct klist_iter i;
  81         struct device *dev;
  82
  83         if (!drv)
  84                 return NULL;
  85
  86         klist_iter_init_node(&drv->p->klist_devices, &i,
  87                              (start ? &start->p->knode_driver : NULL));
  88         while ((dev = next_device(&i)))
  89                 if (match(dev, data) && get_device(dev))
  90                         break;
  91         klist_iter_exit(&i);
  92         return dev;
  93 }
  94 EXPORT_SYMBOL_GPL(driver_find_device);
  95
  96 /**
  97  * driver_create_file - create sysfs file for driver.
  98  * @drv: driver.
  99  * @attr: driver attribute descriptor.
 100  */
 101 int driver_create_file(struct device_driver *drv,
 102                        const struct driver_attribute *attr)
 103 {
 104         int error;
 105         if (drv)
 106                 error = sysfs_create_file(&drv->p->kobj, &attr->attr);
 107         else
 108                 error = -EINVAL;
 109         return error;
 110 }
 111 EXPORT_SYMBOL_GPL(driver_create_file);
 112
 113 /**
 114  * driver_remove_file - remove sysfs file for driver.
 115  * @drv: driver.
 116  * @attr: driver attribute descriptor.
 117  */
 118 void driver_remove_file(struct device_driver *drv,
 119                         const struct driver_attribute *attr)
 120 {
 121         if (drv)
 122                 sysfs_remove_file(&drv->p->kobj, &attr->attr);
 123 }
 124 EXPORT_SYMBOL_GPL(driver_remove_file);
 125
 126 static int driver_add_groups(struct device_driver *drv,
 127                              const struct attribute_group **groups)
 128 {
 129         int error = 0;
 130         int i;
 131
 132         if (groups) {
 133                 for (i = 0; groups[i]; i++) {
 134                         error = sysfs_create_group(&drv->p->kobj, groups[i]);
 135                         if (error) {
 136                                 while (--i >= 0)
 137                                         sysfs_remove_group(&drv->p->kobj,
 138                                                            groups[i]);
 139                                 break;
 140                         }
 141                 }
 142         }
 143         return error;
 144 }
 145
 146 static void driver_remove_groups(struct device_driver *drv,
 147                                  const struct attribute_group **groups)
 148 {
 149         int i;
 150
 151         if (groups)
 152                 for (i = 0; groups[i]; i++)
 153                         sysfs_remove_group(&drv->p->kobj, groups[i]);
 154 }
 155
 156 /**
 157  * driver_register - register driver with bus
 158  * @drv: driver to register
 159  *
 160  * We pass off most of the work to the bus_add_driver() call,
 161  * since most of the things we have to do deal with the bus
 162  * structures.
 163  */
 164 int driver_register(struct device_driver *drv)
 165 {
 166         int ret;
 167         struct device_driver *other;
 168
 169         BUG_ON(!drv->bus->p);
 170
 171         if ((drv->bus->probe && drv->probe) ||
 172             (drv->bus->remove && drv->remove) ||
 173             (drv->bus->shutdown && drv->shutdown))
 174                 printk(KERN_WARNING "Driver '%s' needs updating - please use "
 175                         "bus_type methods\n", drv->name);
 176
 177         other = driver_find(drv->name, drv->bus);
 178         if (other) {
 179                 printk(KERN_ERR "Error: Driver '%s' is already registered, "
 180                         "aborting...\n", drv->name);
 181                 return -EBUSY;
 182         }
 183
 184         ret = bus_add_driver(drv);
 185         if (ret)
 186                 return ret;
 187         ret = driver_add_groups(drv, drv->groups);
 188         if (ret)
 189                 bus_remove_driver(drv);
 190         return ret;
 191 }
 192 EXPORT_SYMBOL_GPL(driver_register);
 193
 194 /**
 195  * driver_unregister - remove driver from system.
 196  * @drv: driver.
 197  *
 198  * Again, we pass off most of the work to the bus-level call.
 199  */
 200 void driver_unregister(struct device_driver *drv)
 201 {
 202         if (!drv || !drv->p) {
 203                 WARN(1, "Unexpected driver unregister!\n");
 204                 return;
 205         }
 206         driver_remove_groups(drv, drv->groups);
 207         bus_remove_driver(drv);
 208 }
 209 EXPORT_SYMBOL_GPL(driver_unregister);
 210
 211 /**
 212  * driver_find - locate driver on a bus by its name.
 213  * @name: name of the driver.
 214  * @bus: bus to scan for the driver.
 215  *
 216  * Call kset_find_obj() to iterate over list of drivers on
 217  * a bus to find driver by name. Return driver if found.
 218  *
 219  * This routine provides no locking to prevent the driver it returns
 220  * from being unregistered or unloaded while the caller is using it.
 221  * The caller is responsible for preventing this.
 222  */
 223 struct device_driver *driver_find(const char *name, struct bus_type *bus)
 224 {
 225         struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
 226         struct driver_private *priv;
 227
 228         if (k) {
 229                 /* Drop reference added by kset_find_obj() */
 230                 kobject_put(k);
 231                 priv = to_driver(k);
 232                 return priv->driver;
 233         }
 234         return NULL;
 235 }
 236 EXPORT_SYMBOL_GPL(driver_find);