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 <linux/sysfs.h>
  19 #include "base.h"
  20
  21 static struct device *next_device(struct klist_iter *i)
  22 {
  23         struct klist_node *n = klist_next(i);
  24         struct device *dev = NULL;
  25         struct device_private *dev_prv;
  26
  27         if (n) {
  28                 dev_prv = to_device_private_driver(n);
  29                 dev = dev_prv->device;
  30         }
  31         return dev;
  32 }
  33
  34 /**
  35  * driver_for_each_device - Iterator for devices bound to a driver.
  36  * @drv: Driver we're iterating.
  37  * @start: Device to begin with
  38  * @data: Data to pass to the callback.
  39  * @fn: Function to call for each device.
  40  *
  41  * Iterate over the @drv's list of devices calling @fn for each one.
  42  */
  43 int driver_for_each_device(struct device_driver *drv, struct device *start,
  44                            void *data, int (*fn)(struct device *, void *))
  45 {
  46         struct klist_iter i;
  47         struct device *dev;
  48         int error = 0;
  49
  50         if (!drv)
  51                 return -EINVAL;
  52
  53         klist_iter_init_node(&drv->p->klist_devices, &i,
  54                              start ? &start->p->knode_driver : NULL);
  55         while ((dev = next_device(&i)) && !error)
  56                 error = fn(dev, data);
  57         klist_iter_exit(&i);
  58         return error;
  59 }
  60 EXPORT_SYMBOL_GPL(driver_for_each_device);
  61
  62 /**
  63  * driver_find_device - device iterator for locating a particular device.
  64  * @drv: The device's driver
  65  * @start: Device to begin with
  66  * @data: Data to pass to match function
  67  * @match: Callback function to check device
  68  *
  69  * This is similar to the driver_for_each_device() function above, but
  70  * it returns a reference to a device that is 'found' for later use, as
  71  * determined by the @match callback.
  72  *
  73  * The callback should return 0 if the device doesn't match and non-zero
  74  * if it does.  If the callback returns non-zero, this function will
  75  * return to the caller and not iterate over any more devices.
  76  */
  77 struct device *driver_find_device(struct device_driver *drv,
  78                                   struct device *start, void *data,
  79                                   int (*match)(struct device *dev, void *data))
  80 {
  81         struct klist_iter i;
  82         struct device *dev;
  83
  84         if (!drv || !drv->p)
  85                 return NULL;
  86
  87         klist_iter_init_node(&drv->p->klist_devices, &i,
  88                              (start ? &start->p->knode_driver : NULL));
  89         while ((dev = next_device(&i)))
  90                 if (match(dev, data) && get_device(dev))
  91                         break;
  92         klist_iter_exit(&i);
  93         return dev;
  94 }
  95 EXPORT_SYMBOL_GPL(driver_find_device);
  96
  97 /**
  98  * driver_create_file - create sysfs file for driver.
  99  * @drv: driver.
 100  * @attr: driver attribute descriptor.
 101  */
 102 int driver_create_file(struct device_driver *drv,
 103                        const struct driver_attribute *attr)
 104 {
 105         int error;
 106         if (drv)
 107                 error = sysfs_create_file(&drv->p->kobj, &attr->attr);
 108         else
 109                 error = -EINVAL;
 110         return error;
 111 }
 112 EXPORT_SYMBOL_GPL(driver_create_file);
 113
 114 /**
 115  * driver_remove_file - remove sysfs file for driver.
 116  * @drv: driver.
 117  * @attr: driver attribute descriptor.
 118  */
 119 void driver_remove_file(struct device_driver *drv,
 120                         const struct driver_attribute *attr)
 121 {
 122         if (drv)
 123                 sysfs_remove_file(&drv->p->kobj, &attr->attr);
 124 }
 125 EXPORT_SYMBOL_GPL(driver_remove_file);
 126
 127 int driver_add_groups(struct device_driver *drv,
 128                       const struct attribute_group **groups)
 129 {
 130         return sysfs_create_groups(&drv->p->kobj, groups);
 131 }
 132
 133 void driver_remove_groups(struct device_driver *drv,
 134                           const struct attribute_group **groups)
 135 {
 136         sysfs_remove_groups(&drv->p->kobj, groups);
 137 }
 138
 139 /**
 140  * driver_register - register driver with bus
 141  * @drv: driver to register
 142  *
 143  * We pass off most of the work to the bus_add_driver() call,
 144  * since most of the things we have to do deal with the bus
 145  * structures.
 146  */
 147 int driver_register(struct device_driver *drv)
 148 {
 149         int ret;
 150         struct device_driver *other;
 151
 152         BUG_ON(!drv->bus->p);
 153
 154         if ((drv->bus->probe && drv->probe) ||
 155             (drv->bus->remove && drv->remove) ||
 156             (drv->bus->shutdown && drv->shutdown))
 157                 printk(KERN_WARNING "Driver '%s' needs updating - please use "
 158                         "bus_type methods\n", drv->name);
 159
 160         other = driver_find(drv->name, drv->bus);
 161         if (other) {
 162                 printk(KERN_ERR "Error: Driver '%s' is already registered, "
 163                         "aborting...\n", drv->name);
 164                 return -EBUSY;
 165         }
 166
 167         ret = bus_add_driver(drv);
 168         if (ret)
 169                 return ret;
 170         ret = driver_add_groups(drv, drv->groups);
 171         if (ret) {
 172                 bus_remove_driver(drv);
 173                 return ret;
 174         }
 175         kobject_uevent(&drv->p->kobj, KOBJ_ADD);
 176
 177         return ret;
 178 }
 179 EXPORT_SYMBOL_GPL(driver_register);
 180
 181 /**
 182  * driver_unregister - remove driver from system.
 183  * @drv: driver.
 184  *
 185  * Again, we pass off most of the work to the bus-level call.
 186  */
 187 void driver_unregister(struct device_driver *drv)
 188 {
 189         if (!drv || !drv->p) {
 190                 WARN(1, "Unexpected driver unregister!\n");
 191                 return;
 192         }
 193         driver_remove_groups(drv, drv->groups);
 194         bus_remove_driver(drv);
 195 }
 196 EXPORT_SYMBOL_GPL(driver_unregister);
 197
 198 /**
 199  * driver_find - locate driver on a bus by its name.
 200  * @name: name of the driver.
 201  * @bus: bus to scan for the driver.
 202  *
 203  * Call kset_find_obj() to iterate over list of drivers on
 204  * a bus to find driver by name. Return driver if found.
 205  *
 206  * This routine provides no locking to prevent the driver it returns
 207  * from being unregistered or unloaded while the caller is using it.
 208  * The caller is responsible for preventing this.
 209  */
 210 struct device_driver *driver_find(const char *name, struct bus_type *bus)
 211 {
 212         struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
 213         struct driver_private *priv;
 214
 215         if (k) {
 216                 /* Drop reference added by kset_find_obj() */
 217                 kobject_put(k);
 218                 priv = to_driver(k);
 219                 return priv->driver;
 220         }
 221         return NULL;
 222 }
 223 EXPORT_SYMBOL_GPL(driver_find);