V4L/DVB (5862): V4L: Add internal ioctl-like interface.
This patch adds an internal ioctl-like interface which can be used in
situations where a single Video4Linux device is implemented by multiple
device drivers. One master device controls one or more slave devices.
The slaves provide Video4Linux ioctl-like interface for the use of the
master.
Only a handful of ioctls are implemented at the moment. More can (and
should) be added as more functionality is required.
Signed-off-by: Sakari Ailus <sakari.ailus@nokia.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/drivers/media/video/v4l2-int-device.c b/drivers/media/video/v4l2-int-device.c
new file mode 100644
index 0000000..7885d9b
--- /dev/null
+++ b/drivers/media/video/v4l2-int-device.c
@@ -0,0 +1,154 @@
+/*
+ * drivers/media/video/v4l2-int-device.c
+ *
+ * V4L2 internal ioctl interface.
+ *
+ * Copyright (C) 2007 Nokia Corporation.
+ *
+ * Contact: Sakari Ailus <sakari.ailus@nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/sort.h>
+#include <linux/string.h>
+
+#include <media/v4l2-int-device.h>
+
+static DEFINE_MUTEX(mutex);
+static LIST_HEAD(int_list);
+
+static void v4l2_int_device_try_attach_all(void)
+{
+ struct list_head *head_master;
+
+ list_for_each(head_master, &int_list) {
+ struct list_head *head_slave;
+ struct v4l2_int_device *m =
+ list_entry(head_master, struct v4l2_int_device, head);
+
+ if (m->type != v4l2_int_type_master)
+ continue;
+
+ list_for_each(head_slave, &int_list) {
+ struct v4l2_int_device *s =
+ list_entry(head_slave,
+ struct v4l2_int_device, head);
+
+ if (s->type != v4l2_int_type_slave)
+ continue;
+
+ /* Slave is connected? */
+ if (s->u.slave->master)
+ continue;
+
+ /* Slave wants to attach to master? */
+ if (s->u.slave->attach_to[0] != 0
+ && strncmp(m->name, s->u.slave->attach_to,
+ V4L2NAMESIZE))
+ continue;
+
+ if (!try_module_get(m->module))
+ continue;
+
+ if (m->u.master->attach(m, s)) {
+ module_put(m->module);
+ continue;
+ }
+
+ s->u.slave->master = m;
+ }
+ }
+}
+
+static int ioctl_sort_cmp(const void *a, const void *b)
+{
+ const struct v4l2_int_ioctl_desc *d1 = a, *d2 = b;
+
+ if (d1->num > d2->num)
+ return 1;
+
+ if (d1->num < d2->num)
+ return -1;
+
+ return 0;
+}
+
+int v4l2_int_device_register(struct v4l2_int_device *d)
+{
+ if (d->type == v4l2_int_type_slave)
+ sort(d->u.slave->ioctls, d->u.slave->num_ioctls,
+ sizeof(struct v4l2_int_ioctl_desc),
+ &ioctl_sort_cmp, NULL);
+ mutex_lock(&mutex);
+ list_add(&d->head, &int_list);
+ v4l2_int_device_try_attach_all();
+ mutex_unlock(&mutex);
+
+ return 0;
+}
+
+void v4l2_int_device_unregister(struct v4l2_int_device *d)
+{
+ mutex_lock(&mutex);
+ list_del(&d->head);
+ if (d->type == v4l2_int_type_slave
+ && d->u.slave->master != NULL) {
+ d->u.slave->master->u.master->detach(d);
+ module_put(d->u.slave->master->module);
+ d->u.slave->master = NULL;
+ }
+ mutex_unlock(&mutex);
+}
+
+static int no_such_ioctl(struct v4l2_int_device *d)
+{
+ return -EINVAL;
+}
+
+/* Adapted from search_extable in extable.c. */
+static v4l2_int_ioctl_func *find_ioctl(struct v4l2_int_slave *slave, int cmd)
+{
+ const struct v4l2_int_ioctl_desc *first = slave->ioctls;
+ const struct v4l2_int_ioctl_desc *last =
+ first + slave->num_ioctls - 1;
+
+ while (first <= last) {
+ const struct v4l2_int_ioctl_desc *mid;
+
+ mid = (last - first) / 2 + first;
+
+ if (mid->num < cmd)
+ first = mid + 1;
+ else if (mid->num > cmd)
+ last = mid - 1;
+ else
+ return mid->func;
+ }
+
+ return &no_such_ioctl;
+}
+
+int v4l2_int_ioctl_0(struct v4l2_int_device *d, int cmd)
+{
+ return ((v4l2_int_ioctl_func_0 *)find_ioctl(d->u.slave, cmd))(d);
+}
+
+int v4l2_int_ioctl_1(struct v4l2_int_device *d, int cmd, void *arg)
+{
+ return ((v4l2_int_ioctl_func_1 *)find_ioctl(d->u.slave, cmd))(d, arg);
+}