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/driver.h>
  12 #include <linux/device.h>
  13 #include <linux/module.h>
  14 #include <linux/errno.h>
  15 #include <linux/slab.h>
  16 #include <linux/string.h>
  17 #include <linux/sysfs.h>
  18 #include "base.h"
  19
  20 static 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  */
  42 int 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 (!error && (dev = next_device(&i)))
  55                 error = fn(dev, data);
  56         klist_iter_exit(&i);
  57         return error;
  58 }
  59 EXPORT_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  */
  76 struct device *driver_find_device(struct device_driver *drv,
  77                                   struct device *start, const void *data,
  78                                   int (*match)(struct device *dev, const 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 }
  94 EXPORT_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  */
 101 int driver_create_file(struct device_driver *drv,
 102                        const struct driver_attribute *attr)
 103 {
 104         int error;
 105
 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         if (!drv->bus->p) {
 153                 pr_err("Driver '%s' was unable to register with bus_type '%s' because the bus was not initialized.\n",
 154                            drv->name, drv->bus->name);
 155                 return -EINVAL;
 156         }
 157
 158         if ((drv->bus->probe && drv->probe) ||
 159             (drv->bus->remove && drv->remove) ||
 160             (drv->bus->shutdown && drv->shutdown))
 161                 printk(KERN_WARNING "Driver '%s' needs updating - please use "
 162                         "bus_type methods\n", drv->name);
 163
 164         other = driver_find(drv->name, drv->bus);
 165         if (other) {
 166                 printk(KERN_ERR "Error: Driver '%s' is already registered, "
 167                         "aborting...\n", drv->name);
 168                 return -EBUSY;
 169         }
 170
 171         ret = bus_add_driver(drv);
 172         if (ret)
 173                 return ret;
 174         ret = driver_add_groups(drv, drv->groups);
 175         if (ret) {
 176                 bus_remove_driver(drv);
 177                 return ret;
 178         }
 179         kobject_uevent(&drv->p->kobj, KOBJ_ADD);
 180
 181         return ret;
 182 }
 183 EXPORT_SYMBOL_GPL(driver_register);
 184
 185 /**
 186  * driver_unregister - remove driver from system.
 187  * @drv: driver.
 188  *
 189  * Again, we pass off most of the work to the bus-level call.
 190  */
 191 void driver_unregister(struct device_driver *drv)
 192 {
 193         if (!drv || !drv->p) {
 194                 WARN(1, "Unexpected driver unregister!\n");
 195                 return;
 196         }
 197         driver_remove_groups(drv, drv->groups);
 198         bus_remove_driver(drv);
 199 }
 200 EXPORT_SYMBOL_GPL(driver_unregister);
 201
 202 /**
 203  * driver_find - locate driver on a bus by its name.
 204  * @name: name of the driver.
 205  * @bus: bus to scan for the driver.
 206  *
 207  * Call kset_find_obj() to iterate over list of drivers on
 208  * a bus to find driver by name. Return driver if found.
 209  *
 210  * This routine provides no locking to prevent the driver it returns
 211  * from being unregistered or unloaded while the caller is using it.
 212  * The caller is responsible for preventing this.
 213  */
 214 struct device_driver *driver_find(const char *name, struct bus_type *bus)
 215 {
 216         struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
 217         struct driver_private *priv;
 218
 219         if (k) {
 220                 /* Drop reference added by kset_find_obj() */
 221                 kobject_put(k);
 222                 priv = to_driver(k);
 223                 return priv->driver;
 224         }
 225         return NULL;
 226 }
 227 EXPORT_SYMBOL_GPL(driver_find);