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 (get_driver(drv)) {
 101                 error = sysfs_create_file(&drv->p->kobj, &attr->attr);
 102                 put_driver(drv);
 103         } else
 104                 error = -EINVAL;
 105         return error;
 106 }
 107 EXPORT_SYMBOL_GPL(driver_create_file);
 108
 109 /**
 110  * driver_remove_file - remove sysfs file for driver.
 111  * @drv: driver.
 112  * @attr: driver attribute descriptor.
 113  */
 114 void driver_remove_file(struct device_driver *drv,
 115                         struct driver_attribute *attr)
 116 {
 117         if (get_driver(drv)) {
 118                 sysfs_remove_file(&drv->p->kobj, &attr->attr);
 119                 put_driver(drv);
 120         }
 121 }
 122 EXPORT_SYMBOL_GPL(driver_remove_file);
 123
 124 /**
 125  * driver_add_kobj - add a kobject below the specified driver
 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
 137         va_start(args, fmt);
 138         name = kvasprintf(GFP_KERNEL, fmt, args);
 139         va_end(args);
 140
 141         if (!name)
 142                 return -ENOMEM;
 143
 144         return kobject_add(kobj, &drv->p->kobj, "%s", name);
 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
 218         if ((drv->bus->probe && drv->probe) ||
 219             (drv->bus->remove && drv->remove) ||
 220             (drv->bus->shutdown && drv->shutdown))
 221                 printk(KERN_WARNING "Driver '%s' needs updating - please use "
 222                         "bus_type methods\n", drv->name);
 223         ret = bus_add_driver(drv);
 224         if (ret)
 225                 return ret;
 226         ret = driver_add_groups(drv, drv->groups);
 227         if (ret)
 228                 bus_remove_driver(drv);
 229         return ret;
 230 }
 231 EXPORT_SYMBOL_GPL(driver_register);
 232
 233 /**
 234  * driver_unregister - remove driver from system.
 235  * @drv: driver.
 236  *
 237  * Again, we pass off most of the work to the bus-level call.
 238  */
 239 void driver_unregister(struct device_driver *drv)
 240 {
 241         driver_remove_groups(drv, drv->groups);
 242         bus_remove_driver(drv);
 243 }
 244 EXPORT_SYMBOL_GPL(driver_unregister);
 245
 246 /**
 247  * driver_find - locate driver on a bus by its name.
 248  * @name: name of the driver.
 249  * @bus: bus to scan for the driver.
 250  *
 251  * Call kset_find_obj() to iterate over list of drivers on
 252  * a bus to find driver by name. Return driver if found.
 253  *
 254  * Note that kset_find_obj increments driver's reference count.
 255  */
 256 struct device_driver *driver_find(const char *name, struct bus_type *bus)
 257 {
 258         struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
 259         struct driver_private *priv;
 260
 261         if (k) {
 262                 priv = to_driver(k);
 263                 return priv->driver;
 264         }
 265         return NULL;
 266 }
 267 EXPORT_SYMBOL_GPL(driver_find);