7885d9b38c922f38e92accedb9f1af88f9020a71
[linux-2.6.git] / drivers / media / video / v4l2-int-device.c
1 /*
2  * drivers/media/video/v4l2-int-device.c
3  *
4  * V4L2 internal ioctl interface.
5  *
6  * Copyright (C) 2007 Nokia Corporation.
7  *
8  * Contact: Sakari Ailus <sakari.ailus@nokia.com>
9  *
10  * This program is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU General Public License
12  * version 2 as published by the Free Software Foundation.
13  *
14  * This program is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17  * General Public License for more details.
18  *
19  * You should have received a copy of the GNU General Public License
20  * along with this program; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
22  * 02110-1301 USA
23  */
24
25 #include <linux/kernel.h>
26 #include <linux/list.h>
27 #include <linux/sort.h>
28 #include <linux/string.h>
29
30 #include <media/v4l2-int-device.h>
31
32 static DEFINE_MUTEX(mutex);
33 static LIST_HEAD(int_list);
34
35 static void v4l2_int_device_try_attach_all(void)
36 {
37         struct list_head *head_master;
38
39         list_for_each(head_master, &int_list) {
40                 struct list_head *head_slave;
41                 struct v4l2_int_device *m =
42                         list_entry(head_master, struct v4l2_int_device, head);
43
44                 if (m->type != v4l2_int_type_master)
45                         continue;
46
47                 list_for_each(head_slave, &int_list) {
48                         struct v4l2_int_device *s =
49                                 list_entry(head_slave,
50                                            struct v4l2_int_device, head);
51
52                         if (s->type != v4l2_int_type_slave)
53                                 continue;
54
55                         /* Slave is connected? */
56                         if (s->u.slave->master)
57                                 continue;
58
59                         /* Slave wants to attach to master? */
60                         if (s->u.slave->attach_to[0] != 0
61                             && strncmp(m->name, s->u.slave->attach_to,
62                                        V4L2NAMESIZE))
63                                 continue;
64
65                         if (!try_module_get(m->module))
66                                 continue;
67
68                         if (m->u.master->attach(m, s)) {
69                                 module_put(m->module);
70                                 continue;
71                         }
72
73                         s->u.slave->master = m;
74                 }
75         }
76 }
77
78 static int ioctl_sort_cmp(const void *a, const void *b)
79 {
80         const struct v4l2_int_ioctl_desc *d1 = a, *d2 = b;
81
82         if (d1->num > d2->num)
83                 return 1;
84
85         if (d1->num < d2->num)
86                 return -1;
87
88         return 0;
89 }
90
91 int v4l2_int_device_register(struct v4l2_int_device *d)
92 {
93         if (d->type == v4l2_int_type_slave)
94                 sort(d->u.slave->ioctls, d->u.slave->num_ioctls,
95                      sizeof(struct v4l2_int_ioctl_desc),
96                      &ioctl_sort_cmp, NULL);
97         mutex_lock(&mutex);
98         list_add(&d->head, &int_list);
99         v4l2_int_device_try_attach_all();
100         mutex_unlock(&mutex);
101
102         return 0;
103 }
104
105 void v4l2_int_device_unregister(struct v4l2_int_device *d)
106 {
107         mutex_lock(&mutex);
108         list_del(&d->head);
109         if (d->type == v4l2_int_type_slave
110             && d->u.slave->master != NULL) {
111                 d->u.slave->master->u.master->detach(d);
112                 module_put(d->u.slave->master->module);
113                 d->u.slave->master = NULL;
114         }
115         mutex_unlock(&mutex);
116 }
117
118 static int no_such_ioctl(struct v4l2_int_device *d)
119 {
120         return -EINVAL;
121 }
122
123 /* Adapted from search_extable in extable.c. */
124 static v4l2_int_ioctl_func *find_ioctl(struct v4l2_int_slave *slave, int cmd)
125 {
126         const struct v4l2_int_ioctl_desc *first = slave->ioctls;
127         const struct v4l2_int_ioctl_desc *last =
128                 first + slave->num_ioctls - 1;
129
130         while (first <= last) {
131                 const struct v4l2_int_ioctl_desc *mid;
132
133                 mid = (last - first) / 2 + first;
134
135                 if (mid->num < cmd)
136                         first = mid + 1;
137                 else if (mid->num > cmd)
138                         last = mid - 1;
139                 else
140                         return mid->func;
141         }
142
143         return &no_such_ioctl;
144 }
145
146 int v4l2_int_ioctl_0(struct v4l2_int_device *d, int cmd)
147 {
148         return ((v4l2_int_ioctl_func_0 *)find_ioctl(d->u.slave, cmd))(d);
149 }
150
151 int v4l2_int_ioctl_1(struct v4l2_int_device *d, int cmd, void *arg)
152 {
153         return ((v4l2_int_ioctl_func_1 *)find_ioctl(d->u.slave, cmd))(d, arg);
154 }