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 #define to_dev(node) container_of(node, struct device, driver_list)
  20
  21
  22 static struct device *next_device(struct klist_iter *i)
  23 {
  24         struct klist_node *n = klist_next(i);
  25         return n ? container_of(n, struct device, knode_driver) : NULL;
  26 }
  27
  28 /**
  29  * driver_for_each_device - Iterator for devices bound to a driver.
  30  * @drv: Driver we're iterating.
  31  * @start: Device to begin with
  32  * @data: Data to pass to the callback.
  33  * @fn: Function to call for each device.
  34  *
  35  * Iterate over the @drv's list of devices calling @fn for each one.
  36  */
  37 int driver_for_each_device(struct device_driver *drv, struct device *start,
  38                            void *data, int (*fn)(struct device *, void *))
  39 {
  40         struct klist_iter i;
  41         struct device *dev;
  42         int error = 0;
  43
  44         if (!drv)
  45                 return -EINVAL;
  46
  47         klist_iter_init_node(&drv->p->klist_devices, &i,
  48                              start ? &start->knode_driver : NULL);
  49         while ((dev = next_device(&i)) && !error)
  50                 error = fn(dev, data);
  51         klist_iter_exit(&i);
  52         return error;
  53 }
  54 EXPORT_SYMBOL_GPL(driver_for_each_device);
  55
  56 /**
  57  * driver_find_device - device iterator for locating a particular device.
  58  * @drv: The device's driver
  59  * @start: Device to begin with
  60  * @data: Data to pass to match function
  61  * @match: Callback function to check device
  62  *
  63  * This is similar to the driver_for_each_device() function above, but
  64  * it returns a reference to a device that is 'found' for later use, as
  65  * determined by the @match callback.
  66  *
  67  * The callback should return 0 if the device doesn't match and non-zero
  68  * if it does.  If the callback returns non-zero, this function will
  69  * return to the caller and not iterate over any more devices.
  70  */
  71 struct device *driver_find_device(struct device_driver *drv,
  72                                   struct device *start, void *data,
  73                                   int (*match)(struct device *dev, void *data))
  74 {
  75         struct klist_iter i;
  76         struct device *dev;
  77
  78         if (!drv)
  79                 return NULL;
  80
  81         klist_iter_init_node(&drv->p->klist_devices, &i,
  82                              (start ? &start->knode_driver : NULL));
  83         while ((dev = next_device(&i)))
  84                 if (match(dev, data) && get_device(dev))
  85                         break;
  86         klist_iter_exit(&i);
  87         return dev;
  88 }
  89 EXPORT_SYMBOL_GPL(driver_find_device);
  90
  91 /**
  92  * driver_create_file - create sysfs file for driver.
  93  * @drv: driver.
  94  * @attr: driver attribute descriptor.
  95  */
  96 int driver_create_file(struct device_driver *drv,
  97                        struct driver_attribute *attr)
  98 {
  99         int error;
 100         if (drv)
 101                 error = sysfs_create_file(&drv->p->kobj, &attr->attr);
 102         else
 103                 error = -EINVAL;
 104         return error;
 105 }
 106 EXPORT_SYMBOL_GPL(driver_create_file);
 107
 108 /**
 109  * driver_remove_file - remove sysfs file for driver.
 110  * @drv: driver.
 111  * @attr: driver attribute descriptor.
 112  */
 113 void driver_remove_file(struct device_driver *drv,
 114                         struct driver_attribute *attr)
 115 {
 116         if (drv)
 117                 sysfs_remove_file(&drv->p->kobj, &attr->attr);
 118 }
 119 EXPORT_SYMBOL_GPL(driver_remove_file);
 120
 121 /**
 122  * driver_add_kobj - add a kobject below the specified driver
 123  * @drv: requesting device driver
 124  * @kobj: kobject to add below this driver
 125  * @fmt: format string that names the kobject
 126  *
 127  * You really don't want to do this, this is only here due to one looney
 128  * iseries driver, go poke those developers if you are annoyed about
 129  * this...
 130  */
 131 int driver_add_kobj(struct device_driver *drv, struct kobject *kobj,
 132                     const char *fmt, ...)
 133 {
 134         va_list args;
 135         char *name;
 136         int ret;
 137
 138         va_start(args, fmt);
 139         name = kvasprintf(GFP_KERNEL, fmt, args);
 140         va_end(args);
 141
 142         if (!name)
 143                 return -ENOMEM;
 144
 145         ret = kobject_add(kobj, &drv->p->kobj, "%s", name);
 146         kfree(name);
 147         return ret;
 148 }
 149 EXPORT_SYMBOL_GPL(driver_add_kobj);
 150
 151 /**
 152  * get_driver - increment driver reference count.
 153  * @drv: driver.
 154  */
 155 struct device_driver *get_driver(struct device_driver *drv)
 156 {
 157         if (drv) {
 158                 struct driver_private *priv;
 159                 struct kobject *kobj;
 160
 161                 kobj = kobject_get(&drv->p->kobj);
 162                 priv = to_driver(kobj);
 163                 return priv->driver;
 164         }
 165         return NULL;
 166 }
 167 EXPORT_SYMBOL_GPL(get_driver);
 168
 169 /**
 170  * put_driver - decrement driver's refcount.
 171  * @drv: driver.
 172  */
 173 void put_driver(struct device_driver *drv)
 174 {
 175         kobject_put(&drv->p->kobj);
 176 }
 177 EXPORT_SYMBOL_GPL(put_driver);
 178
 179 static int driver_add_groups(struct device_driver *drv,
 180                              struct attribute_group **groups)
 181 {
 182         int error = 0;
 183         int i;
 184
 185         if (groups) {
 186                 for (i = 0; groups[i]; i++) {
 187                         error = sysfs_create_group(&drv->p->kobj, groups[i]);
 188                         if (error) {
 189                                 while (--i >= 0)
 190                                         sysfs_remove_group(&drv->p->kobj,
 191                                                            groups[i]);
 192                                 break;
 193                         }
 194                 }
 195         }
 196         return error;
 197 }
 198
 199 static void driver_remove_groups(struct device_driver *drv,
 200                                  struct attribute_group **groups)
 201 {
 202         int i;
 203
 204         if (groups)
 205                 for (i = 0; groups[i]; i++)
 206                         sysfs_remove_group(&drv->p->kobj, groups[i]);
 207 }
 208
 209 /**
 210  * driver_register - register driver with bus
 211  * @drv: driver to register
 212  *
 213  * We pass off most of the work to the bus_add_driver() call,
 214  * since most of the things we have to do deal with the bus
 215  * structures.
 216  */
 217 int driver_register(struct device_driver *drv)
 218 {
 219         int ret;
 220         struct device_driver *other;
 221
 222         if ((drv->bus->probe && drv->probe) ||
 223             (drv->bus->remove && drv->remove) ||
 224             (drv->bus->shutdown && drv->shutdown))
 225                 printk(KERN_WARNING "Driver '%s' needs updating - please use "
 226                         "bus_type methods\n", drv->name);
 227
 228         other = driver_find(drv->name, drv->bus);
 229         if (other) {
 230                 put_driver(other);
 231                 printk(KERN_ERR "Error: Driver '%s' is already registered, "
 232                         "aborting...\n", drv->name);
 233                 return -EEXIST;
 234         }
 235
 236         ret = bus_add_driver(drv);
 237         if (ret)
 238                 return ret;
 239         ret = driver_add_groups(drv, drv->groups);
 240         if (ret)
 241                 bus_remove_driver(drv);
 242         return ret;
 243 }
 244 EXPORT_SYMBOL_GPL(driver_register);
 245
 246 /**
 247  * driver_unregister - remove driver from system.
 248  * @drv: driver.
 249  *
 250  * Again, we pass off most of the work to the bus-level call.
 251  */
 252 void driver_unregister(struct device_driver *drv)
 253 {
 254         driver_remove_groups(drv, drv->groups);
 255         bus_remove_driver(drv);
 256 }
 257 EXPORT_SYMBOL_GPL(driver_unregister);
 258
 259 /**
 260  * driver_find - locate driver on a bus by its name.
 261  * @name: name of the driver.
 262  * @bus: bus to scan for the driver.
 263  *
 264  * Call kset_find_obj() to iterate over list of drivers on
 265  * a bus to find driver by name. Return driver if found.
 266  *
 267  * Note that kset_find_obj increments driver's reference count.
 268  */
 269 struct device_driver *driver_find(const char *name, struct bus_type *bus)
 270 {
 271         struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
 272         struct driver_private *priv;
 273
 274         if (k) {
 275                 priv = to_driver(k);
 276                 return priv->driver;
 277         }
 278         return NULL;
 279 }
 280 EXPORT_SYMBOL_GPL(driver_find);