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/string.h>
  17 #include "base.h"
  18
  19 static struct device *next_device(struct klist_iter *i)
  20 {
  21         struct klist_node *n = klist_next(i);
  22         return n ? container_of(n, struct device, knode_driver) : NULL;
  23 }
  24
  25 /**
  26  * driver_for_each_device - Iterator for devices bound to a driver.
  27  * @drv: Driver we're iterating.
  28  * @start: Device to begin with
  29  * @data: Data to pass to the callback.
  30  * @fn: Function to call for each device.
  31  *
  32  * Iterate over the @drv's list of devices calling @fn for each one.
  33  */
  34 int driver_for_each_device(struct device_driver *drv, struct device *start,
  35                            void *data, int (*fn)(struct device *, void *))
  36 {
  37         struct klist_iter i;
  38         struct device *dev;
  39         int error = 0;
  40
  41         if (!drv)
  42                 return -EINVAL;
  43
  44         klist_iter_init_node(&drv->p->klist_devices, &i,
  45                              start ? &start->knode_driver : NULL);
  46         while ((dev = next_device(&i)) && !error)
  47                 error = fn(dev, data);
  48         klist_iter_exit(&i);
  49         return error;
  50 }
  51 EXPORT_SYMBOL_GPL(driver_for_each_device);
  52
  53 /**
  54  * driver_find_device - device iterator for locating a particular device.
  55  * @drv: The device's driver
  56  * @start: Device to begin with
  57  * @data: Data to pass to match function
  58  * @match: Callback function to check device
  59  *
  60  * This is similar to the driver_for_each_device() function above, but
  61  * it returns a reference to a device that is 'found' for later use, as
  62  * determined by the @match callback.
  63  *
  64  * The callback should return 0 if the device doesn't match and non-zero
  65  * if it does.  If the callback returns non-zero, this function will
  66  * return to the caller and not iterate over any more devices.
  67  */
  68 struct device *driver_find_device(struct device_driver *drv,
  69                                   struct device *start, void *data,
  70                                   int (*match)(struct device *dev, void *data))
  71 {
  72         struct klist_iter i;
  73         struct device *dev;
  74
  75         if (!drv)
  76                 return NULL;
  77
  78         klist_iter_init_node(&drv->p->klist_devices, &i,
  79                              (start ? &start->knode_driver : NULL));
  80         while ((dev = next_device(&i)))
  81                 if (match(dev, data) && get_device(dev))
  82                         break;
  83         klist_iter_exit(&i);
  84         return dev;
  85 }
  86 EXPORT_SYMBOL_GPL(driver_find_device);
  87
  88 /**
  89  * driver_create_file - create sysfs file for driver.
  90  * @drv: driver.
  91  * @attr: driver attribute descriptor.
  92  */
  93 int driver_create_file(struct device_driver *drv,
  94                        struct driver_attribute *attr)
  95 {
  96         int error;
  97         if (drv)
  98                 error = sysfs_create_file(&drv->p->kobj, &attr->attr);
  99         else
 100                 error = -EINVAL;
 101         return error;
 102 }
 103 EXPORT_SYMBOL_GPL(driver_create_file);
 104
 105 /**
 106  * driver_remove_file - remove sysfs file for driver.
 107  * @drv: driver.
 108  * @attr: driver attribute descriptor.
 109  */
 110 void driver_remove_file(struct device_driver *drv,
 111                         struct driver_attribute *attr)
 112 {
 113         if (drv)
 114                 sysfs_remove_file(&drv->p->kobj, &attr->attr);
 115 }
 116 EXPORT_SYMBOL_GPL(driver_remove_file);
 117
 118 /**
 119  * driver_add_kobj - add a kobject below the specified driver
 120  * @drv: requesting device driver
 121  * @kobj: kobject to add below this driver
 122  * @fmt: format string that names the kobject
 123  *
 124  * You really don't want to do this, this is only here due to one looney
 125  * iseries driver, go poke those developers if you are annoyed about
 126  * this...
 127  */
 128 int driver_add_kobj(struct device_driver *drv, struct kobject *kobj,
 129                     const char *fmt, ...)
 130 {
 131         va_list args;
 132         char *name;
 133         int ret;
 134
 135         va_start(args, fmt);
 136         name = kvasprintf(GFP_KERNEL, fmt, args);
 137         va_end(args);
 138
 139         if (!name)
 140                 return -ENOMEM;
 141
 142         ret = kobject_add(kobj, &drv->p->kobj, "%s", name);
 143         kfree(name);
 144         return ret;
 145 }
 146 EXPORT_SYMBOL_GPL(driver_add_kobj);
 147
 148 /**
 149  * get_driver - increment driver reference count.
 150  * @drv: driver.
 151  */
 152 struct device_driver *get_driver(struct device_driver *drv)
 153 {
 154         if (drv) {
 155                 struct driver_private *priv;
 156                 struct kobject *kobj;
 157
 158                 kobj = kobject_get(&drv->p->kobj);
 159                 priv = to_driver(kobj);
 160                 return priv->driver;
 161         }
 162         return NULL;
 163 }
 164 EXPORT_SYMBOL_GPL(get_driver);
 165
 166 /**
 167  * put_driver - decrement driver's refcount.
 168  * @drv: driver.
 169  */
 170 void put_driver(struct device_driver *drv)
 171 {
 172         kobject_put(&drv->p->kobj);
 173 }
 174 EXPORT_SYMBOL_GPL(put_driver);
 175
 176 static int driver_add_groups(struct device_driver *drv,
 177                              struct attribute_group **groups)
 178 {
 179         int error = 0;
 180         int i;
 181
 182         if (groups) {
 183                 for (i = 0; groups[i]; i++) {
 184                         error = sysfs_create_group(&drv->p->kobj, groups[i]);
 185                         if (error) {
 186                                 while (--i >= 0)
 187                                         sysfs_remove_group(&drv->p->kobj,
 188                                                            groups[i]);
 189                                 break;
 190                         }
 191                 }
 192         }
 193         return error;
 194 }
 195
 196 static void driver_remove_groups(struct device_driver *drv,
 197                                  struct attribute_group **groups)
 198 {
 199         int i;
 200
 201         if (groups)
 202                 for (i = 0; groups[i]; i++)
 203                         sysfs_remove_group(&drv->p->kobj, groups[i]);
 204 }
 205
 206 /**
 207  * driver_register - register driver with bus
 208  * @drv: driver to register
 209  *
 210  * We pass off most of the work to the bus_add_driver() call,
 211  * since most of the things we have to do deal with the bus
 212  * structures.
 213  */
 214 int driver_register(struct device_driver *drv)
 215 {
 216         int ret;
 217         struct device_driver *other;
 218
 219         if ((drv->bus->probe && drv->probe) ||
 220             (drv->bus->remove && drv->remove) ||
 221             (drv->bus->shutdown && drv->shutdown))
 222                 printk(KERN_WARNING "Driver '%s' needs updating - please use "
 223                         "bus_type methods\n", drv->name);
 224
 225         other = driver_find(drv->name, drv->bus);
 226         if (other) {
 227                 put_driver(other);
 228                 printk(KERN_ERR "Error: Driver '%s' is already registered, "
 229                         "aborting...\n", drv->name);
 230                 return -EEXIST;
 231         }
 232
 233         ret = bus_add_driver(drv);
 234         if (ret)
 235                 return ret;
 236         ret = driver_add_groups(drv, drv->groups);
 237         if (ret)
 238                 bus_remove_driver(drv);
 239         return ret;
 240 }
 241 EXPORT_SYMBOL_GPL(driver_register);
 242
 243 /**
 244  * driver_unregister - remove driver from system.
 245  * @drv: driver.
 246  *
 247  * Again, we pass off most of the work to the bus-level call.
 248  */
 249 void driver_unregister(struct device_driver *drv)
 250 {
 251         driver_remove_groups(drv, drv->groups);
 252         bus_remove_driver(drv);
 253 }
 254 EXPORT_SYMBOL_GPL(driver_unregister);
 255
 256 /**
 257  * driver_find - locate driver on a bus by its name.
 258  * @name: name of the driver.
 259  * @bus: bus to scan for the driver.
 260  *
 261  * Call kset_find_obj() to iterate over list of drivers on
 262  * a bus to find driver by name. Return driver if found.
 263  *
 264  * Note that kset_find_obj increments driver's reference count.
 265  */
 266 struct device_driver *driver_find(const char *name, struct bus_type *bus)
 267 {
 268         struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
 269         struct driver_private *priv;
 270
 271         if (k) {
 272                 priv = to_driver(k);
 273                 return priv->driver;
 274         }
 275         return NULL;
 276 }
 277 EXPORT_SYMBOL_GPL(driver_find);