drivers/base/driver.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * driver.c - centralized device driver management
   4  *
   5  * Copyright (c) 2002-3 Patrick Mochel
   6  * Copyright (c) 2002-3 Open Source Development Labs
   7  * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
   8  * Copyright (c) 2007 Novell Inc.
   9  */
  10
  11 #include <linux/device.h>
  12 #include <linux/module.h>
  13 #include <linux/errno.h>
  14 #include <linux/slab.h>
  15 #include <linux/string.h>
  16 #include <linux/sysfs.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 (!error && (dev = next_device(&i)))
  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 || !drv->p)
  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
 105         if (drv)
 106                 error = sysfs_create_file(&drv->p->kobj, &attr->attr);
 107         else
 108                 error = -EINVAL;
 109         return error;
 110 }
 111 EXPORT_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  */
 118 void 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 }
 124 EXPORT_SYMBOL_GPL(driver_remove_file);
 125
 126 int driver_add_groups(struct device_driver *drv,
 127                       const struct attribute_group **groups)
 128 {
 129         return sysfs_create_groups(&drv->p->kobj, groups);
 130 }
 131
 132 void driver_remove_groups(struct device_driver *drv,
 133                           const struct attribute_group **groups)
 134 {
 135         sysfs_remove_groups(&drv->p->kobj, groups);
 136 }
 137
 138 /**
 139  * driver_register - register driver with bus
 140  * @drv: driver to register
 141  *
 142  * We pass off most of the work to the bus_add_driver() call,
 143  * since most of the things we have to do deal with the bus
 144  * structures.
 145  */
 146 int driver_register(struct device_driver *drv)
 147 {
 148         int ret;
 149         struct device_driver *other;
 150
 151         BUG_ON(!drv->bus->p);
 152
 153         if ((drv->bus->probe && drv->probe) ||
 154             (drv->bus->remove && drv->remove) ||
 155             (drv->bus->shutdown && drv->shutdown))
 156                 printk(KERN_WARNING "Driver '%s' needs updating - please use "
 157                         "bus_type methods\n", drv->name);
 158
 159         other = driver_find(drv->name, drv->bus);
 160         if (other) {
 161                 printk(KERN_ERR "Error: Driver '%s' is already registered, "
 162                         "aborting...\n", drv->name);
 163                 return -EBUSY;
 164         }
 165
 166         ret = bus_add_driver(drv);
 167         if (ret)
 168                 return ret;
 169         ret = driver_add_groups(drv, drv->groups);
 170         if (ret) {
 171                 bus_remove_driver(drv);
 172                 return ret;
 173         }
 174         kobject_uevent(&drv->p->kobj, KOBJ_ADD);
 175
 176         return ret;
 177 }
 178 EXPORT_SYMBOL_GPL(driver_register);
 179
 180 /**
 181  * driver_unregister - remove driver from system.
 182  * @drv: driver.
 183  *
 184  * Again, we pass off most of the work to the bus-level call.
 185  */
 186 void driver_unregister(struct device_driver *drv)
 187 {
 188         if (!drv || !drv->p) {
 189                 WARN(1, "Unexpected driver unregister!\n");
 190                 return;
 191         }
 192         driver_remove_groups(drv, drv->groups);
 193         bus_remove_driver(drv);
 194 }
 195 EXPORT_SYMBOL_GPL(driver_unregister);
 196
 197 /**
 198  * driver_find - locate driver on a bus by its name.
 199  * @name: name of the driver.
 200  * @bus: bus to scan for the driver.
 201  *
 202  * Call kset_find_obj() to iterate over list of drivers on
 203  * a bus to find driver by name. Return driver if found.
 204  *
 205  * This routine provides no locking to prevent the driver it returns
 206  * from being unregistered or unloaded while the caller is using it.
 207  * The caller is responsible for preventing this.
 208  */
 209 struct device_driver *driver_find(const char *name, struct bus_type *bus)
 210 {
 211         struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
 212         struct driver_private *priv;
 213
 214         if (k) {
 215                 /* Drop reference added by kset_find_obj() */
 216                 kobject_put(k);
 217                 priv = to_driver(k);
 218                 return priv->driver;
 219         }
 220         return NULL;
 221 }
 222 EXPORT_SYMBOL_GPL(driver_find);