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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 <linux/sysfs.h>
19 #include "base.h"
20 
next_device(struct klist_iter * i)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  */
driver_for_each_device(struct device_driver * drv,struct device * start,void * data,int (* fn)(struct device *,void *))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  */
driver_find_device(struct device_driver * drv,struct device * start,void * data,int (* match)(struct device * dev,void * data))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  */
driver_create_file(struct device_driver * drv,const struct driver_attribute * attr)102 int 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 }
113 EXPORT_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  */
driver_remove_file(struct device_driver * drv,const struct driver_attribute * attr)120 void 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 }
126 EXPORT_SYMBOL_GPL(driver_remove_file);
127 
driver_add_groups(struct device_driver * drv,const struct attribute_group ** groups)128 int 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 
driver_remove_groups(struct device_driver * drv,const struct attribute_group ** groups)134 void 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  */
driver_register(struct device_driver * drv)148 int 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 }
180 EXPORT_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  */
driver_unregister(struct device_driver * drv)188 void 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 }
197 EXPORT_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  */
driver_find(const char * name,struct bus_type * bus)211 struct 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 }
224 EXPORT_SYMBOL_GPL(driver_find);
225