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 v4l2_int_device *m, *s;
  38
  39         list_for_each_entry(m, &int_list, head) {
  40                 if (m->type != v4l2_int_type_master)
  41                         continue;
  42
  43                 list_for_each_entry(s, &int_list, head) {
  44                         if (s->type != v4l2_int_type_slave)
  45                                 continue;
  46
  47                         /* Slave is connected? */
  48                         if (s->u.slave->master)
  49                                 continue;
  50
  51                         /* Slave wants to attach to master? */
  52                         if (s->u.slave->attach_to[0] != 0
  53                             && strncmp(m->name, s->u.slave->attach_to,
  54                                        V4L2NAMESIZE))
  55                                 continue;
  56
  57                         if (!try_module_get(m->module))
  58                                 continue;
  59
  60                         s->u.slave->master = m;
  61                         if (m->u.master->attach(s)) {
  62                                 s->u.slave->master = NULL;
  63                                 module_put(m->module);
  64                                 continue;
  65                         }
  66                 }
  67         }
  68 }
  69
  70 static int ioctl_sort_cmp(const void *a, const void *b)
  71 {
  72         const struct v4l2_int_ioctl_desc *d1 = a, *d2 = b;
  73
  74         if (d1->num > d2->num)
  75                 return 1;
  76
  77         if (d1->num < d2->num)
  78                 return -1;
  79
  80         return 0;
  81 }
  82
  83 int v4l2_int_device_register(struct v4l2_int_device *d)
  84 {
  85         if (d->type == v4l2_int_type_slave)
  86                 sort(d->u.slave->ioctls, d->u.slave->num_ioctls,
  87                      sizeof(struct v4l2_int_ioctl_desc),
  88                      &ioctl_sort_cmp, NULL);
  89         mutex_lock(&mutex);
  90         list_add(&d->head, &int_list);
  91         v4l2_int_device_try_attach_all();
  92         mutex_unlock(&mutex);
  93
  94         return 0;
  95 }
  96 EXPORT_SYMBOL_GPL(v4l2_int_device_register);
  97
  98 void v4l2_int_device_unregister(struct v4l2_int_device *d)
  99 {
 100         mutex_lock(&mutex);
 101         list_del(&d->head);
 102         if (d->type == v4l2_int_type_slave
 103             && d->u.slave->master != NULL) {
 104                 d->u.slave->master->u.master->detach(d);
 105                 module_put(d->u.slave->master->module);
 106                 d->u.slave->master = NULL;
 107         }
 108         mutex_unlock(&mutex);
 109 }
 110 EXPORT_SYMBOL_GPL(v4l2_int_device_unregister);
 111
 112 /* Adapted from search_extable in extable.c. */
 113 static v4l2_int_ioctl_func *find_ioctl(struct v4l2_int_slave *slave, int cmd,
 114                                        v4l2_int_ioctl_func *no_such_ioctl)
 115 {
 116         const struct v4l2_int_ioctl_desc *first = slave->ioctls;
 117         const struct v4l2_int_ioctl_desc *last =
 118                 first + slave->num_ioctls - 1;
 119
 120         while (first <= last) {
 121                 const struct v4l2_int_ioctl_desc *mid;
 122
 123                 mid = (last - first) / 2 + first;
 124
 125                 if (mid->num < cmd)
 126                         first = mid + 1;
 127                 else if (mid->num > cmd)
 128                         last = mid - 1;
 129                 else
 130                         return mid->func;
 131         }
 132
 133         return no_such_ioctl;
 134 }
 135
 136 static int no_such_ioctl_0(struct v4l2_int_device *d)
 137 {
 138         return -ENOIOCTLCMD;
 139 }
 140
 141 int v4l2_int_ioctl_0(struct v4l2_int_device *d, int cmd)
 142 {
 143         return ((v4l2_int_ioctl_func_0 *)
 144                 find_ioctl(d->u.slave, cmd,
 145                            (v4l2_int_ioctl_func *)no_such_ioctl_0))(d);
 146 }
 147
 148 static int no_such_ioctl_1(struct v4l2_int_device *d, void *arg)
 149 {
 150         return -ENOIOCTLCMD;
 151 }
 152
 153 int v4l2_int_ioctl_1(struct v4l2_int_device *d, int cmd, void *arg)
 154 {
 155         return ((v4l2_int_ioctl_func_1 *)
 156                 find_ioctl(d->u.slave, cmd,
 157                            (v4l2_int_ioctl_func *)no_such_ioctl_1))(d, arg);
 158 }
 159
 160 MODULE_LICENSE("GPL");