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 #include <linux/module.h>
  30
  31 #include <media/v4l2-int-device.h>
  32
  33 static DEFINE_MUTEX(mutex);
  34 static LIST_HEAD(int_list);
  35
  36 void v4l2_int_device_try_attach_all(void)
  37 {
  38         struct v4l2_int_device *m, *s;
  39
  40         list_for_each_entry(m, &int_list, head) {
  41                 if (m->type != v4l2_int_type_master)
  42                         continue;
  43
  44                 list_for_each_entry(s, &int_list, head) {
  45                         if (s->type != v4l2_int_type_slave)
  46                                 continue;
  47
  48                         /* Slave is connected? */
  49                         if (s->u.slave->master)
  50                                 continue;
  51
  52                         /* Slave wants to attach to master? */
  53                         if (s->u.slave->attach_to[0] != 0
  54                             && strncmp(m->name, s->u.slave->attach_to,
  55                                        V4L2NAMESIZE))
  56                                 continue;
  57
  58                         if (!try_module_get(m->module))
  59                                 continue;
  60
  61                         s->u.slave->master = m;
  62                         if (m->u.master->attach(s)) {
  63                                 s->u.slave->master = NULL;
  64                                 module_put(m->module);
  65                                 continue;
  66                         }
  67                 }
  68         }
  69 }
  70 EXPORT_SYMBOL_GPL(v4l2_int_device_try_attach_all);
  71
  72 static int ioctl_sort_cmp(const void *a, const void *b)
  73 {
  74         const struct v4l2_int_ioctl_desc *d1 = a, *d2 = b;
  75
  76         if (d1->num > d2->num)
  77                 return 1;
  78
  79         if (d1->num < d2->num)
  80                 return -1;
  81
  82         return 0;
  83 }
  84
  85 int v4l2_int_device_register(struct v4l2_int_device *d)
  86 {
  87         if (d->type == v4l2_int_type_slave)
  88                 sort(d->u.slave->ioctls, d->u.slave->num_ioctls,
  89                      sizeof(struct v4l2_int_ioctl_desc),
  90                      &ioctl_sort_cmp, NULL);
  91         mutex_lock(&mutex);
  92         list_add(&d->head, &int_list);
  93         v4l2_int_device_try_attach_all();
  94         mutex_unlock(&mutex);
  95
  96         return 0;
  97 }
  98 EXPORT_SYMBOL_GPL(v4l2_int_device_register);
  99
 100 void v4l2_int_device_unregister(struct v4l2_int_device *d)
 101 {
 102         mutex_lock(&mutex);
 103         list_del(&d->head);
 104         if (d->type == v4l2_int_type_slave
 105             && d->u.slave->master != NULL) {
 106                 d->u.slave->master->u.master->detach(d);
 107                 module_put(d->u.slave->master->module);
 108                 d->u.slave->master = NULL;
 109         }
 110         mutex_unlock(&mutex);
 111 }
 112 EXPORT_SYMBOL_GPL(v4l2_int_device_unregister);
 113
 114 /* Adapted from search_extable in extable.c. */
 115 static v4l2_int_ioctl_func *find_ioctl(struct v4l2_int_slave *slave, int cmd,
 116                                        v4l2_int_ioctl_func *no_such_ioctl)
 117 {
 118         const struct v4l2_int_ioctl_desc *first = slave->ioctls;
 119         const struct v4l2_int_ioctl_desc *last =
 120                 first + slave->num_ioctls - 1;
 121
 122         while (first <= last) {
 123                 const struct v4l2_int_ioctl_desc *mid;
 124
 125                 mid = (last - first) / 2 + first;
 126
 127                 if (mid->num < cmd)
 128                         first = mid + 1;
 129                 else if (mid->num > cmd)
 130                         last = mid - 1;
 131                 else
 132                         return mid->func;
 133         }
 134
 135         return no_such_ioctl;
 136 }
 137
 138 static int no_such_ioctl_0(struct v4l2_int_device *d)
 139 {
 140         return -ENOIOCTLCMD;
 141 }
 142
 143 int v4l2_int_ioctl_0(struct v4l2_int_device *d, int cmd)
 144 {
 145         return ((v4l2_int_ioctl_func_0 *)
 146                 find_ioctl(d->u.slave, cmd,
 147                            (v4l2_int_ioctl_func *)no_such_ioctl_0))(d);
 148 }
 149 EXPORT_SYMBOL_GPL(v4l2_int_ioctl_0);
 150
 151 static int no_such_ioctl_1(struct v4l2_int_device *d, void *arg)
 152 {
 153         return -ENOIOCTLCMD;
 154 }
 155
 156 int v4l2_int_ioctl_1(struct v4l2_int_device *d, int cmd, void *arg)
 157 {
 158         return ((v4l2_int_ioctl_func_1 *)
 159                 find_ioctl(d->u.slave, cmd,
 160                            (v4l2_int_ioctl_func *)no_such_ioctl_1))(d, arg);
 161 }
 162 EXPORT_SYMBOL_GPL(v4l2_int_ioctl_1);
 163
 164 MODULE_LICENSE("GPL");