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 EXPORT_SYMBOL_GPL(v4l2_int_device_register);
 105
 106 void v4l2_int_device_unregister(struct v4l2_int_device *d)
 107 {
 108         mutex_lock(&mutex);
 109         list_del(&d->head);
 110         if (d->type == v4l2_int_type_slave
 111             && d->u.slave->master != NULL) {
 112                 d->u.slave->master->u.master->detach(d);
 113                 module_put(d->u.slave->master->module);
 114                 d->u.slave->master = NULL;
 115         }
 116         mutex_unlock(&mutex);
 117 }
 118 EXPORT_SYMBOL_GPL(v4l2_int_device_unregister);
 119
 120 /* Adapted from search_extable in extable.c. */
 121 static v4l2_int_ioctl_func *find_ioctl(struct v4l2_int_slave *slave, int cmd,
 122                                        v4l2_int_ioctl_func *no_such_ioctl)
 123 {
 124         const struct v4l2_int_ioctl_desc *first = slave->ioctls;
 125         const struct v4l2_int_ioctl_desc *last =
 126                 first + slave->num_ioctls - 1;
 127
 128         while (first <= last) {
 129                 const struct v4l2_int_ioctl_desc *mid;
 130
 131                 mid = (last - first) / 2 + first;
 132
 133                 if (mid->num < cmd)
 134                         first = mid + 1;
 135                 else if (mid->num > cmd)
 136                         last = mid - 1;
 137                 else
 138                         return mid->func;
 139         }
 140
 141         return no_such_ioctl;
 142 }
 143
 144 static int no_such_ioctl_0(struct v4l2_int_device *d)
 145 {
 146         return -ENOIOCTLCMD;
 147 }
 148
 149 int v4l2_int_ioctl_0(struct v4l2_int_device *d, int cmd)
 150 {
 151         return ((v4l2_int_ioctl_func_0 *)
 152                 find_ioctl(d->u.slave, cmd,
 153                            (v4l2_int_ioctl_func *)no_such_ioctl_0))(d);
 154 }
 155
 156 static int no_such_ioctl_1(struct v4l2_int_device *d, void *arg)
 157 {
 158         return -ENOIOCTLCMD;
 159 }
 160
 161 int v4l2_int_ioctl_1(struct v4l2_int_device *d, int cmd, void *arg)
 162 {
 163         return ((v4l2_int_ioctl_func_1 *)
 164                 find_ioctl(d->u.slave, cmd,
 165                            (v4l2_int_ioctl_func *)no_such_ioctl_1))(d, arg);
 166 }