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 /**
 127  * driver_add_kobj - add a kobject below the specified driver
 128  * @drv: requesting device driver
 129  * @kobj: kobject to add below this driver
 130  * @fmt: format string that names the kobject
 131  *
 132  * You really don't want to do this, this is only here due to one looney
 133  * iseries driver, go poke those developers if you are annoyed about
 134  * this...
 135  */
 136 int driver_add_kobj(struct device_driver *drv, struct kobject *kobj,
 137                     const char *fmt, ...)
 138 {
 139         va_list args;
 140         char *name;
 141         int ret;
 142
 143         va_start(args, fmt);
 144         name = kvasprintf(GFP_KERNEL, fmt, args);
 145         va_end(args);
 146
 147         if (!name)
 148                 return -ENOMEM;
 149
 150         ret = kobject_add(kobj, &drv->p->kobj, "%s", name);
 151         kfree(name);
 152         return ret;
 153 }
 154 EXPORT_SYMBOL_GPL(driver_add_kobj);
 155
 156 /**
 157  * get_driver - increment driver reference count.
 158  * @drv: driver.
 159  */
 160 struct device_driver *get_driver(struct device_driver *drv)
 161 {
 162         if (drv) {
 163                 struct driver_private *priv;
 164                 struct kobject *kobj;
 165
 166                 kobj = kobject_get(&drv->p->kobj);
 167                 priv = to_driver(kobj);
 168                 return priv->driver;
 169         }
 170         return NULL;
 171 }
 172 EXPORT_SYMBOL_GPL(get_driver);
 173
 174 /**
 175  * put_driver - decrement driver's refcount.
 176  * @drv: driver.
 177  */
 178 void put_driver(struct device_driver *drv)
 179 {
 180         kobject_put(&drv->p->kobj);
 181 }
 182 EXPORT_SYMBOL_GPL(put_driver);
 183
 184 static int driver_add_groups(struct device_driver *drv,
 185                              const struct attribute_group **groups)
 186 {
 187         int error = 0;
 188         int i;
 189
 190         if (groups) {
 191                 for (i = 0; groups[i]; i++) {
 192                         error = sysfs_create_group(&drv->p->kobj, groups[i]);
 193                         if (error) {
 194                                 while (--i >= 0)
 195                                         sysfs_remove_group(&drv->p->kobj,
 196                                                            groups[i]);
 197                                 break;
 198                         }
 199                 }
 200         }
 201         return error;
 202 }
 203
 204 static void driver_remove_groups(struct device_driver *drv,
 205                                  const struct attribute_group **groups)
 206 {
 207         int i;
 208
 209         if (groups)
 210                 for (i = 0; groups[i]; i++)
 211                         sysfs_remove_group(&drv->p->kobj, groups[i]);
 212 }
 213
 214 /**
 215  * driver_register - register driver with bus
 216  * @drv: driver to register
 217  *
 218  * We pass off most of the work to the bus_add_driver() call,
 219  * since most of the things we have to do deal with the bus
 220  * structures.
 221  */
 222 int driver_register(struct device_driver *drv)
 223 {
 224         int ret;
 225         struct device_driver *other;
 226
 227         BUG_ON(!drv->bus->p);
 228
 229         if ((drv->bus->probe && drv->probe) ||
 230             (drv->bus->remove && drv->remove) ||
 231             (drv->bus->shutdown && drv->shutdown))
 232                 printk(KERN_WARNING "Driver '%s' needs updating - please use "
 233                         "bus_type methods\n", drv->name);
 234
 235         other = driver_find(drv->name, drv->bus);
 236         if (other) {
 237                 put_driver(other);
 238                 printk(KERN_ERR "Error: Driver '%s' is already registered, "
 239                         "aborting...\n", drv->name);
 240                 return -EBUSY;
 241         }
 242
 243         ret = bus_add_driver(drv);
 244         if (ret)
 245                 return ret;
 246         ret = driver_add_groups(drv, drv->groups);
 247         if (ret)
 248                 bus_remove_driver(drv);
 249         return ret;
 250 }
 251 EXPORT_SYMBOL_GPL(driver_register);
 252
 253 /**
 254  * driver_unregister - remove driver from system.
 255  * @drv: driver.
 256  *
 257  * Again, we pass off most of the work to the bus-level call.
 258  */
 259 void driver_unregister(struct device_driver *drv)
 260 {
 261         if (!drv || !drv->p) {
 262                 WARN(1, "Unexpected driver unregister!\n");
 263                 return;
 264         }
 265         driver_remove_groups(drv, drv->groups);
 266         bus_remove_driver(drv);
 267 }
 268 EXPORT_SYMBOL_GPL(driver_unregister);
 269
 270 /**
 271  * driver_find - locate driver on a bus by its name.
 272  * @name: name of the driver.
 273  * @bus: bus to scan for the driver.
 274  *
 275  * Call kset_find_obj() to iterate over list of drivers on
 276  * a bus to find driver by name. Return driver if found.
 277  *
 278  * Note that kset_find_obj increments driver's reference count.
 279  */
 280 struct device_driver *driver_find(const char *name, struct bus_type *bus)
 281 {
 282         struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
 283         struct driver_private *priv;
 284
 285         if (k) {
 286                 priv = to_driver(k);
 287                 return priv->driver;
 288         }
 289         return NULL;
 290 }
 291 EXPORT_SYMBOL_GPL(driver_find);