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 struct v4l2_int_slave dummy_slave = {
  71         /* Dummy pointer to avoid underflow in find_ioctl. */
  72         .ioctls = (void *)0x80000000,
  73         .num_ioctls = 0,
  74 };
  75
  76 static struct v4l2_int_device dummy = {
  77         .type = v4l2_int_type_slave,
  78         .u = {
  79                 .slave = &dummy_slave,
  80         },
  81 };
  82
  83 struct v4l2_int_device *v4l2_int_device_dummy()
  84 {
  85         return &dummy;
  86 }
  87 EXPORT_SYMBOL_GPL(v4l2_int_device_dummy);
  88
  89 void v4l2_int_device_try_attach_all(void)
  90 {
  91         mutex_lock(&mutex);
  92         __v4l2_int_device_try_attach_all();
  93         mutex_unlock(&mutex);
  94 }
  95
  96 EXPORT_SYMBOL_GPL(v4l2_int_device_try_attach_all);
  97
  98 static int ioctl_sort_cmp(const void *a, const void *b)
  99 {
 100         const struct v4l2_int_ioctl_desc *d1 = a, *d2 = b;
 101
 102         if (d1->num > d2->num)
 103                 return 1;
 104
 105         if (d1->num < d2->num)
 106                 return -1;
 107
 108         return 0;
 109 }
 110
 111 int v4l2_int_device_register(struct v4l2_int_device *d)
 112 {
 113         if (d->type == v4l2_int_type_slave)
 114                 sort(d->u.slave->ioctls, d->u.slave->num_ioctls,
 115                      sizeof(struct v4l2_int_ioctl_desc),
 116                      &ioctl_sort_cmp, NULL);
 117         mutex_lock(&mutex);
 118         list_add(&d->head, &int_list);
 119         __v4l2_int_device_try_attach_all();
 120         mutex_unlock(&mutex);
 121
 122         return 0;
 123 }
 124 EXPORT_SYMBOL_GPL(v4l2_int_device_register);
 125
 126 void v4l2_int_device_unregister(struct v4l2_int_device *d)
 127 {
 128         mutex_lock(&mutex);
 129         list_del(&d->head);
 130         if (d->type == v4l2_int_type_slave
 131             && d->u.slave->master != NULL) {
 132                 d->u.slave->master->u.master->detach(d);
 133                 module_put(d->u.slave->master->module);
 134                 d->u.slave->master = NULL;
 135         }
 136         mutex_unlock(&mutex);
 137 }
 138 EXPORT_SYMBOL_GPL(v4l2_int_device_unregister);
 139
 140 /* Adapted from search_extable in extable.c. */
 141 static v4l2_int_ioctl_func *find_ioctl(struct v4l2_int_slave *slave, int cmd,
 142                                        v4l2_int_ioctl_func *no_such_ioctl)
 143 {
 144         const struct v4l2_int_ioctl_desc *first = slave->ioctls;
 145         const struct v4l2_int_ioctl_desc *last =
 146                 first + slave->num_ioctls - 1;
 147
 148         while (first <= last) {
 149                 const struct v4l2_int_ioctl_desc *mid;
 150
 151                 mid = (last - first) / 2 + first;
 152
 153                 if (mid->num < cmd)
 154                         first = mid + 1;
 155                 else if (mid->num > cmd)
 156                         last = mid - 1;
 157                 else
 158                         return mid->func;
 159         }
 160
 161         return no_such_ioctl;
 162 }
 163
 164 static int no_such_ioctl_0(struct v4l2_int_device *d)
 165 {
 166         return -ENOIOCTLCMD;
 167 }
 168
 169 int v4l2_int_ioctl_0(struct v4l2_int_device *d, int cmd)
 170 {
 171         return ((v4l2_int_ioctl_func_0 *)
 172                 find_ioctl(d->u.slave, cmd,
 173                            (v4l2_int_ioctl_func *)no_such_ioctl_0))(d);
 174 }
 175 EXPORT_SYMBOL_GPL(v4l2_int_ioctl_0);
 176
 177 static int no_such_ioctl_1(struct v4l2_int_device *d, void *arg)
 178 {
 179         return -ENOIOCTLCMD;
 180 }
 181
 182 int v4l2_int_ioctl_1(struct v4l2_int_device *d, int cmd, void *arg)
 183 {
 184         return ((v4l2_int_ioctl_func_1 *)
 185                 find_ioctl(d->u.slave, cmd,
 186                            (v4l2_int_ioctl_func *)no_such_ioctl_1))(d, arg);
 187 }
 188 EXPORT_SYMBOL_GPL(v4l2_int_ioctl_1);
 189
 190 MODULE_LICENSE("GPL");