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
21static 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 */
43int 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}
60EXPORT_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 */
77struct 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}
95EXPORT_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 */
102int driver_create_file(struct device_driver *drv,
103		       const struct driver_attribute *attr)
104{
105	int error;
106
107	if (drv)
108		error = sysfs_create_file(&drv->p->kobj, &attr->attr);
109	else
110		error = -EINVAL;
111	return error;
112}
113EXPORT_SYMBOL_GPL(driver_create_file);
114
115/**
116 * driver_remove_file - remove sysfs file for driver.
117 * @drv: driver.
118 * @attr: driver attribute descriptor.
119 */
120void driver_remove_file(struct device_driver *drv,
121			const struct driver_attribute *attr)
122{
123	if (drv)
124		sysfs_remove_file(&drv->p->kobj, &attr->attr);
125}
126EXPORT_SYMBOL_GPL(driver_remove_file);
127
128int driver_add_groups(struct device_driver *drv,
129		      const struct attribute_group **groups)
130{
131	return sysfs_create_groups(&drv->p->kobj, groups);
132}
133
134void driver_remove_groups(struct device_driver *drv,
135			  const struct attribute_group **groups)
136{
137	sysfs_remove_groups(&drv->p->kobj, groups);
138}
139
140/**
141 * driver_register - register driver with bus
142 * @drv: driver to register
143 *
144 * We pass off most of the work to the bus_add_driver() call,
145 * since most of the things we have to do deal with the bus
146 * structures.
147 */
148int driver_register(struct device_driver *drv)
149{
150	int ret;
151	struct device_driver *other;
152
153	BUG_ON(!drv->bus->p);
154
155	if ((drv->bus->probe && drv->probe) ||
156	    (drv->bus->remove && drv->remove) ||
157	    (drv->bus->shutdown && drv->shutdown))
158		printk(KERN_WARNING "Driver '%s' needs updating - please use "
159			"bus_type methods\n", drv->name);
160
161	other = driver_find(drv->name, drv->bus);
162	if (other) {
163		printk(KERN_ERR "Error: Driver '%s' is already registered, "
164			"aborting...\n", drv->name);
165		return -EBUSY;
166	}
167
168	ret = bus_add_driver(drv);
169	if (ret)
170		return ret;
171	ret = driver_add_groups(drv, drv->groups);
172	if (ret) {
173		bus_remove_driver(drv);
174		return ret;
175	}
176	kobject_uevent(&drv->p->kobj, KOBJ_ADD);
177
178	return ret;
179}
180EXPORT_SYMBOL_GPL(driver_register);
181
182/**
183 * driver_unregister - remove driver from system.
184 * @drv: driver.
185 *
186 * Again, we pass off most of the work to the bus-level call.
187 */
188void driver_unregister(struct device_driver *drv)
189{
190	if (!drv || !drv->p) {
191		WARN(1, "Unexpected driver unregister!\n");
192		return;
193	}
194	driver_remove_groups(drv, drv->groups);
195	bus_remove_driver(drv);
196}
197EXPORT_SYMBOL_GPL(driver_unregister);
198
199/**
200 * driver_find - locate driver on a bus by its name.
201 * @name: name of the driver.
202 * @bus: bus to scan for the driver.
203 *
204 * Call kset_find_obj() to iterate over list of drivers on
205 * a bus to find driver by name. Return driver if found.
206 *
207 * This routine provides no locking to prevent the driver it returns
208 * from being unregistered or unloaded while the caller is using it.
209 * The caller is responsible for preventing this.
210 */
211struct device_driver *driver_find(const char *name, struct bus_type *bus)
212{
213	struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
214	struct driver_private *priv;
215
216	if (k) {
217		/* Drop reference added by kset_find_obj() */
218		kobject_put(k);
219		priv = to_driver(k);
220		return priv->driver;
221	}
222	return NULL;
223}
224EXPORT_SYMBOL_GPL(driver_find);
225