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/init.h>
17#include <linux/kmod.h>
18#include <linux/mutex.h>
19
20#include <net/irda/irda.h>
21
22#include "sir-dev.h"
23
24/**************************************************************************
25 *
26 * dongle registration and attachment
27 *
28 */
29
30static LIST_HEAD(dongle_list);			/* list of registered dongle drivers */
31static DEFINE_MUTEX(dongle_list_lock);		/* protects the list */
32
33int irda_register_dongle(struct dongle_driver *new)
34{
35	struct list_head *entry;
36	struct dongle_driver *drv;
37
38	IRDA_DEBUG(0, "%s : registering dongle \"%s\" (%d).\n",
39		   __FUNCTION__, new->driver_name, new->type);
40
41	mutex_lock(&dongle_list_lock);
42	list_for_each(entry, &dongle_list) {
43		drv = list_entry(entry, struct dongle_driver, dongle_list);
44		if (new->type == drv->type) {
45			mutex_unlock(&dongle_list_lock);
46			return -EEXIST;
47		}
48	}
49	list_add(&new->dongle_list, &dongle_list);
50	mutex_unlock(&dongle_list_lock);
51	return 0;
52}
53EXPORT_SYMBOL(irda_register_dongle);
54
55int irda_unregister_dongle(struct dongle_driver *drv)
56{
57	mutex_lock(&dongle_list_lock);
58	list_del(&drv->dongle_list);
59	mutex_unlock(&dongle_list_lock);
60	return 0;
61}
62EXPORT_SYMBOL(irda_unregister_dongle);
63
64int sirdev_get_dongle(struct sir_dev *dev, IRDA_DONGLE type)
65{
66	struct list_head *entry;
67	const struct dongle_driver *drv = NULL;
68	int err = -EINVAL;
69
70#ifdef CONFIG_KMOD
71	request_module("irda-dongle-%d", type);
72#endif
73
74	if (dev->dongle_drv != NULL)
75		return -EBUSY;
76
77	/* serialize access to the list of registered dongles */
78	mutex_lock(&dongle_list_lock);
79
80	list_for_each(entry, &dongle_list) {
81		drv = list_entry(entry, struct dongle_driver, dongle_list);
82		if (drv->type == type)
83			break;
84		else
85			drv = NULL;
86	}
87
88	if (!drv) {
89		err = -ENODEV;
90		goto out_unlock;	/* no such dongle */
91	}
92
93	/* handling of SMP races with dongle module removal - three cases:
94	 * 1) dongle driver was already unregistered - then we haven't found the
95	 *	requested dongle above and are already out here
96	 * 2) the module is already marked deleted but the driver is still
97	 *	registered - then the try_module_get() below will fail
98	 * 3) the try_module_get() below succeeds before the module is marked
99	 *	deleted - then sys_delete_module() fails and prevents the removal
100	 *	because the module is in use.
101	 */
102
103	if (!try_module_get(drv->owner)) {
104		err = -ESTALE;
105		goto out_unlock;	/* rmmod already pending */
106	}
107	dev->dongle_drv = drv;
108
109	if (!drv->open  ||  (err=drv->open(dev))!=0)
110		goto out_reject;		/* failed to open driver */
111
112	mutex_unlock(&dongle_list_lock);
113	return 0;
114
115out_reject:
116	dev->dongle_drv = NULL;
117	module_put(drv->owner);
118out_unlock:
119	mutex_unlock(&dongle_list_lock);
120	return err;
121}
122
123int sirdev_put_dongle(struct sir_dev *dev)
124{
125	const struct dongle_driver *drv = dev->dongle_drv;
126
127	if (drv) {
128		if (drv->close)
129			drv->close(dev);		/* close this dongle instance */
130
131		dev->dongle_drv = NULL;			/* unlink the dongle driver */
132		module_put(drv->owner);/* decrement driver's module refcount */
133	}
134
135	return 0;
136}
137