1/*********************************************************************
2 *
3 *	sir_dongle.c:	manager for serial dongle protocol drivers
4 *
5 *	Copyright (c) 2002 Martin Diehl
6 *
7 *	This program is free software; you can redistribute it and/or
8 *	modify it under the terms of the GNU General Public License as
9 *	published by the Free Software Foundation; either version 2 of
10 *	the License, or (at your option) any later version.
11 *
12 ********************************************************************/
13
14#include <linux/module.h>
15#include <linux/kernel.h>
16#include <linux/kmod.h>
17#include <linux/mutex.h>
18
19#include <net/irda/irda.h>
20
21#include "sir-dev.h"
22
23/**************************************************************************
24 *
25 * dongle registration and attachment
26 *
27 */
28
29static LIST_HEAD(dongle_list);			/* list of registered dongle drivers */
30static DEFINE_MUTEX(dongle_list_lock);		/* protects the list */
31
32int irda_register_dongle(struct dongle_driver *new)
33{
34	struct list_head *entry;
35	struct dongle_driver *drv;
36
37	pr_debug("%s : registering dongle \"%s\" (%d).\n",
38		 __func__, new->driver_name, new->type);
39
40	mutex_lock(&dongle_list_lock);
41	list_for_each(entry, &dongle_list) {
42		drv = list_entry(entry, struct dongle_driver, dongle_list);
43		if (new->type == drv->type) {
44			mutex_unlock(&dongle_list_lock);
45			return -EEXIST;
46		}
47	}
48	list_add(&new->dongle_list, &dongle_list);
49	mutex_unlock(&dongle_list_lock);
50	return 0;
51}
52EXPORT_SYMBOL(irda_register_dongle);
53
54int irda_unregister_dongle(struct dongle_driver *drv)
55{
56	mutex_lock(&dongle_list_lock);
57	list_del(&drv->dongle_list);
58	mutex_unlock(&dongle_list_lock);
59	return 0;
60}
61EXPORT_SYMBOL(irda_unregister_dongle);
62
63int sirdev_get_dongle(struct sir_dev *dev, IRDA_DONGLE type)
64{
65	struct list_head *entry;
66	const struct dongle_driver *drv = NULL;
67	int err = -EINVAL;
68
69	request_module("irda-dongle-%d", type);
70
71	if (dev->dongle_drv != NULL)
72		return -EBUSY;
73
74	/* serialize access to the list of registered dongles */
75	mutex_lock(&dongle_list_lock);
76
77	list_for_each(entry, &dongle_list) {
78		drv = list_entry(entry, struct dongle_driver, dongle_list);
79		if (drv->type == type)
80			break;
81		else
82			drv = NULL;
83	}
84
85	if (!drv) {
86		err = -ENODEV;
87		goto out_unlock;	/* no such dongle */
88	}
89
90	/* handling of SMP races with dongle module removal - three cases:
91	 * 1) dongle driver was already unregistered - then we haven't found the
92	 *	requested dongle above and are already out here
93	 * 2) the module is already marked deleted but the driver is still
94	 *	registered - then the try_module_get() below will fail
95	 * 3) the try_module_get() below succeeds before the module is marked
96	 *	deleted - then sys_delete_module() fails and prevents the removal
97	 *	because the module is in use.
98	 */
99
100	if (!try_module_get(drv->owner)) {
101		err = -ESTALE;
102		goto out_unlock;	/* rmmod already pending */
103	}
104	dev->dongle_drv = drv;
105
106	if (!drv->open  ||  (err=drv->open(dev))!=0)
107		goto out_reject;		/* failed to open driver */
108
109	mutex_unlock(&dongle_list_lock);
110	return 0;
111
112out_reject:
113	dev->dongle_drv = NULL;
114	module_put(drv->owner);
115out_unlock:
116	mutex_unlock(&dongle_list_lock);
117	return err;
118}
119
120int sirdev_put_dongle(struct sir_dev *dev)
121{
122	const struct dongle_driver *drv = dev->dongle_drv;
123
124	if (drv) {
125		if (drv->close)
126			drv->close(dev);		/* close this dongle instance */
127
128		dev->dongle_drv = NULL;			/* unlink the dongle driver */
129		module_put(drv->owner);/* decrement driver's module refcount */
130	}
131
132	return 0;
133}
134