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         struct device *dev = NULL;
  23         struct device_private *dev_prv;
  24
  25         if (n) {
  26                 dev_prv = to_device_private_driver(n);
  27                 dev = dev_prv->device;
  28         }
  29         return dev;
  30 }
  31
  32 /**
  33  * driver_for_each_device - Iterator for devices bound to a driver.
  34  * @drv: Driver we're iterating.
  35  * @start: Device to begin with
  36  * @data: Data to pass to the callback.
  37  * @fn: Function to call for each device.
  38  *
  39  * Iterate over the @drv's list of devices calling @fn for each one.
  40  */
  41 int driver_for_each_device(struct device_driver *drv, struct device *start,
  42                            void *data, int (*fn)(struct device *, void *))
  43 {
  44         struct klist_iter i;
  45         struct device *dev;
  46         int error = 0;
  47
  48         if (!drv)
  49                 return -EINVAL;
  50
  51         klist_iter_init_node(&drv->p->klist_devices, &i,
  52                              start ? &start->p->knode_driver : NULL);
  53         while ((dev = next_device(&i)) && !error)
  54                 error = fn(dev, data);
  55         klist_iter_exit(&i);
  56         return error;
  57 }
  58 EXPORT_SYMBOL_GPL(driver_for_each_device);
  59
  60 /**
  61  * driver_find_device - device iterator for locating a particular device.
  62  * @drv: The device's driver
  63  * @start: Device to begin with
  64  * @data: Data to pass to match function
  65  * @match: Callback function to check device
  66  *
  67  * This is similar to the driver_for_each_device() function above, but
  68  * it returns a reference to a device that is 'found' for later use, as
  69  * determined by the @match callback.
  70  *
  71  * The callback should return 0 if the device doesn't match and non-zero
  72  * if it does.  If the callback returns non-zero, this function will
  73  * return to the caller and not iterate over any more devices.
  74  */
  75 struct device *driver_find_device(struct device_driver *drv,
  76                                   struct device *start, void *data,
  77                                   int (*match)(struct device *dev, void *data))
  78 {
  79         struct klist_iter i;
  80         struct device *dev;
  81
  82         if (!drv)
  83                 return NULL;
  84
  85         klist_iter_init_node(&drv->p->klist_devices, &i,
  86                              (start ? &start->p->knode_driver : NULL));
  87         while ((dev = next_device(&i)))
  88                 if (match(dev, data) && get_device(dev))
  89                         break;
  90         klist_iter_exit(&i);
  91         return dev;
  92 }
  93 EXPORT_SYMBOL_GPL(driver_find_device);
  94
  95 /**
  96  * driver_create_file - create sysfs file for driver.
  97  * @drv: driver.
  98  * @attr: driver attribute descriptor.
  99  */
 100 int driver_create_file(struct device_driver *drv,
 101                        const struct driver_attribute *attr)
 102 {
 103         int error;
 104         if (drv)
 105                 error = sysfs_create_file(&drv->p->kobj, &attr->attr);
 106         else
 107                 error = -EINVAL;
 108         return error;
 109 }
 110 EXPORT_SYMBOL_GPL(driver_create_file);
 111
 112 /**
 113  * driver_remove_file - remove sysfs file for driver.
 114  * @drv: driver.
 115  * @attr: driver attribute descriptor.
 116  */
 117 void driver_remove_file(struct device_driver *drv,
 118                         const struct driver_attribute *attr)
 119 {
 120         if (drv)
 121                 sysfs_remove_file(&drv->p->kobj, &attr->attr);
 122 }
 123 EXPORT_SYMBOL_GPL(driver_remove_file);
 124
 125 /**
 126  * driver_add_kobj - add a kobject below the specified driver
 127  * @drv: requesting device driver
 128  * @kobj: kobject to add below this driver
 129  * @fmt: format string that names the kobject
 130  *
 131  * You really don't want to do this, this is only here due to one looney
 132  * iseries driver, go poke those developers if you are annoyed about
 133  * this...
 134  */
 135 int driver_add_kobj(struct device_driver *drv, struct kobject *kobj,
 136                     const char *fmt, ...)
 137 {
 138         va_list args;
 139         char *name;
 140         int ret;
 141
 142         va_start(args, fmt);
 143         name = kvasprintf(GFP_KERNEL, fmt, args);
 144         va_end(args);
 145
 146         if (!name)
 147                 return -ENOMEM;
 148
 149         ret = kobject_add(kobj, &drv->p->kobj, "%s", name);
 150         kfree(name);
 151         return ret;
 152 }
 153 EXPORT_SYMBOL_GPL(driver_add_kobj);
 154
 155 /**
 156  * get_driver - increment driver reference count.
 157  * @drv: driver.
 158  */
 159 struct device_driver *get_driver(struct device_driver *drv)
 160 {
 161         if (drv) {
 162                 struct driver_private *priv;
 163                 struct kobject *kobj;
 164
 165                 kobj = kobject_get(&drv->p->kobj);
 166                 priv = to_driver(kobj);
 167                 return priv->driver;
 168         }
 169         return NULL;
 170 }
 171 EXPORT_SYMBOL_GPL(get_driver);
 172
 173 /**
 174  * put_driver - decrement driver's refcount.
 175  * @drv: driver.
 176  */
 177 void put_driver(struct device_driver *drv)
 178 {
 179         kobject_put(&drv->p->kobj);
 180 }
 181 EXPORT_SYMBOL_GPL(put_driver);
 182
 183 static int driver_add_groups(struct device_driver *drv,
 184                              const struct attribute_group **groups)
 185 {
 186         int error = 0;
 187         int i;
 188
 189         if (groups) {
 190                 for (i = 0; groups[i]; i++) {
 191                         error = sysfs_create_group(&drv->p->kobj, groups[i]);
 192                         if (error) {
 193                                 while (--i >= 0)
 194                                         sysfs_remove_group(&drv->p->kobj,
 195                                                            groups[i]);
 196                                 break;
 197                         }
 198                 }
 199         }
 200         return error;
 201 }
 202
 203 static void driver_remove_groups(struct device_driver *drv,
 204                                  const struct attribute_group **groups)
 205 {
 206         int i;
 207
 208         if (groups)
 209                 for (i = 0; groups[i]; i++)
 210                         sysfs_remove_group(&drv->p->kobj, groups[i]);
 211 }
 212
 213 /**
 214  * driver_register - register driver with bus
 215  * @drv: driver to register
 216  *
 217  * We pass off most of the work to the bus_add_driver() call,
 218  * since most of the things we have to do deal with the bus
 219  * structures.
 220  */
 221 int driver_register(struct device_driver *drv)
 222 {
 223         int ret;
 224         struct device_driver *other;
 225
 226         BUG_ON(!drv->bus->p);
 227
 228         if ((drv->bus->probe && drv->probe) ||
 229             (drv->bus->remove && drv->remove) ||
 230             (drv->bus->shutdown && drv->shutdown))
 231                 printk(KERN_WARNING "Driver '%s' needs updating - please use "
 232                         "bus_type methods\n", drv->name);
 233
 234         other = driver_find(drv->name, drv->bus);
 235         if (other) {
 236                 put_driver(other);
 237                 printk(KERN_ERR "Error: Driver '%s' is already registered, "
 238                         "aborting...\n", drv->name);
 239                 return -EBUSY;
 240         }
 241
 242         ret = bus_add_driver(drv);
 243         if (ret)
 244                 return ret;
 245         ret = driver_add_groups(drv, drv->groups);
 246         if (ret)
 247                 bus_remove_driver(drv);
 248         return ret;
 249 }
 250 EXPORT_SYMBOL_GPL(driver_register);
 251
 252 /**
 253  * driver_unregister - remove driver from system.
 254  * @drv: driver.
 255  *
 256  * Again, we pass off most of the work to the bus-level call.
 257  */
 258 void driver_unregister(struct device_driver *drv)
 259 {
 260         if (!drv || !drv->p) {
 261                 WARN(1, "Unexpected driver unregister!\n");
 262                 return;
 263         }
 264         driver_remove_groups(drv, drv->groups);
 265         bus_remove_driver(drv);
 266 }
 267 EXPORT_SYMBOL_GPL(driver_unregister);
 268
 269 /**
 270  * driver_find - locate driver on a bus by its name.
 271  * @name: name of the driver.
 272  * @bus: bus to scan for the driver.
 273  *
 274  * Call kset_find_obj() to iterate over list of drivers on
 275  * a bus to find driver by name. Return driver if found.
 276  *
 277  * Note that kset_find_obj increments driver's reference count.
 278  */
 279 struct device_driver *driver_find(const char *name, struct bus_type *bus)
 280 {
 281         struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
 282         struct driver_private *priv;
 283
 284         if (k) {
 285                 priv = to_driver(k);
 286                 return priv->driver;
 287         }
 288         return NULL;
 289 }
 290 EXPORT_SYMBOL_GPL(driver_find);