LXR linux/drivers/media/v4l2-core/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
  33static DEFINE_MUTEX(mutex);
  34static LIST_HEAD(int_list);
  35
  36void 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}
  70EXPORT_SYMBOL_GPL(v4l2_int_device_try_attach_all);
  71
  72static 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
  85int 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}
  98EXPORT_SYMBOL_GPL(v4l2_int_device_register);
  99
 100void 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}
 112EXPORT_SYMBOL_GPL(v4l2_int_device_unregister);
 113
 114/* Adapted from search_extable in extable.c. */
 115static 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
 138static int no_such_ioctl_0(struct v4l2_int_device *d)
 139{
 140        return -ENOIOCTLCMD;
 141}
 142
 143int 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}
 149EXPORT_SYMBOL_GPL(v4l2_int_ioctl_0);
 150
 151static int no_such_ioctl_1(struct v4l2_int_device *d, void *arg)
 152{
 153        return -ENOIOCTLCMD;
 154}
 155
 156int 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}
 162EXPORT_SYMBOL_GPL(v4l2_int_ioctl_1);
 163
 164MODULE_LICENSE("GPL");
 165