LXR linux/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
  32static DEFINE_MUTEX(mutex);
  33static LIST_HEAD(int_list);
  34
  35static 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                        if (m->u.master->attach(m, s)) {
  61                                module_put(m->module);
  62                                continue;
  63                        }
  64
  65                        s->u.slave->master = m;
  66                }
  67        }
  68}
  69
  70static 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
  83int 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}
  96EXPORT_SYMBOL_GPL(v4l2_int_device_register);
  97
  98void 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}
 110EXPORT_SYMBOL_GPL(v4l2_int_device_unregister);
 111
 112/* Adapted from search_extable in extable.c. */
 113static 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
 136static int no_such_ioctl_0(struct v4l2_int_device *d)
 137{
 138        return -ENOIOCTLCMD;
 139}
 140
 141int 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
 148static int no_such_ioctl_1(struct v4l2_int_device *d, void *arg)
 149{
 150        return -ENOIOCTLCMD;
 151}
 152
 153int 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