linux/drivers/base/driver.c
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   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
  20static 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 */
  42int 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}
  59EXPORT_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 */
  76struct 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 || !drv->p)
  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}
  94EXPORT_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 */
 101int 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}
 111EXPORT_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 */
 118void 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}
 124EXPORT_SYMBOL_GPL(driver_remove_file);
 125
 126static int driver_add_groups(struct device_driver *drv,
 127                             const struct attribute_group **groups)
 128{
 129        int error = 0;
 130        int i;
 131
 132        if (groups) {
 133                for (i = 0; groups[i]; i++) {
 134                        error = sysfs_create_group(&drv->p->kobj, groups[i]);
 135                        if (error) {
 136                                while (--i >= 0)
 137                                        sysfs_remove_group(&drv->p->kobj,
 138                                                           groups[i]);
 139                                break;
 140                        }
 141                }
 142        }
 143        return error;
 144}
 145
 146static void driver_remove_groups(struct device_driver *drv,
 147                                 const struct attribute_group **groups)
 148{
 149        int i;
 150
 151        if (groups)
 152                for (i = 0; groups[i]; i++)
 153                        sysfs_remove_group(&drv->p->kobj, groups[i]);
 154}
 155
 156/**
 157 * driver_register - register driver with bus
 158 * @drv: driver to register
 159 *
 160 * We pass off most of the work to the bus_add_driver() call,
 161 * since most of the things we have to do deal with the bus
 162 * structures.
 163 */
 164int driver_register(struct device_driver *drv)
 165{
 166        int ret;
 167        struct device_driver *other;
 168
 169        BUG_ON(!drv->bus->p);
 170
 171        if ((drv->bus->probe && drv->probe) ||
 172            (drv->bus->remove && drv->remove) ||
 173            (drv->bus->shutdown && drv->shutdown))
 174                printk(KERN_WARNING "Driver '%s' needs updating - please use "
 175                        "bus_type methods\n", drv->name);
 176
 177        other = driver_find(drv->name, drv->bus);
 178        if (other) {
 179                printk(KERN_ERR "Error: Driver '%s' is already registered, "
 180                        "aborting...\n", drv->name);
 181                return -EBUSY;
 182        }
 183
 184        ret = bus_add_driver(drv);
 185        if (ret)
 186                return ret;
 187        ret = driver_add_groups(drv, drv->groups);
 188        if (ret) {
 189                bus_remove_driver(drv);
 190                return ret;
 191        }
 192        kobject_uevent(&drv->p->kobj, KOBJ_ADD);
 193
 194        return ret;
 195}
 196EXPORT_SYMBOL_GPL(driver_register);
 197
 198/**
 199 * driver_unregister - remove driver from system.
 200 * @drv: driver.
 201 *
 202 * Again, we pass off most of the work to the bus-level call.
 203 */
 204void driver_unregister(struct device_driver *drv)
 205{
 206        if (!drv || !drv->p) {
 207                WARN(1, "Unexpected driver unregister!\n");
 208                return;
 209        }
 210        driver_remove_groups(drv, drv->groups);
 211        bus_remove_driver(drv);
 212}
 213EXPORT_SYMBOL_GPL(driver_unregister);
 214
 215/**
 216 * driver_find - locate driver on a bus by its name.
 217 * @name: name of the driver.
 218 * @bus: bus to scan for the driver.
 219 *
 220 * Call kset_find_obj() to iterate over list of drivers on
 221 * a bus to find driver by name. Return driver if found.
 222 *
 223 * This routine provides no locking to prevent the driver it returns
 224 * from being unregistered or unloaded while the caller is using it.
 225 * The caller is responsible for preventing this.
 226 */
 227struct device_driver *driver_find(const char *name, struct bus_type *bus)
 228{
 229        struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
 230        struct driver_private *priv;
 231
 232        if (k) {
 233                /* Drop reference added by kset_find_obj() */
 234                kobject_put(k);
 235                priv = to_driver(k);
 236                return priv->driver;
 237        }
 238        return NULL;
 239}
 240EXPORT_SYMBOL_GPL(driver_find);
 241
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