The media_devnode structure provides support for registering and
unregistering character devices using a dynamic major number. Reference
counting is handled internally, making device drivers easier to write
without having to solve the open/disconnect race condition issue over
and over again.
The code is based on video/v4l2-dev.c.
Signed-off-by: Laurent Pinchart laurent.pinch...@ideasonboard.com
---
drivers/media/Makefile|8 +-
drivers/media/media-devnode.c | 326 +
include/media/media-devnode.h | 84 +++
3 files changed, 416 insertions(+), 2 deletions(-)
create mode 100644 drivers/media/media-devnode.c
create mode 100644 include/media/media-devnode.h
diff --git a/drivers/media/Makefile b/drivers/media/Makefile
index 499b081..c1b5938 100644
--- a/drivers/media/Makefile
+++ b/drivers/media/Makefile
@@ -2,7 +2,11 @@
# Makefile for the kernel multimedia device drivers.
#
+media-objs := media-devnode.o
+
+obj-$(CONFIG_MEDIA_SUPPORT)+= media.o
+
obj-y += common/ IR/ video/
-obj-$(CONFIG_VIDEO_DEV) += radio/
-obj-$(CONFIG_DVB_CORE) += dvb/
+obj-$(CONFIG_VIDEO_DEV)+= radio/
+obj-$(CONFIG_DVB_CORE) += dvb/
diff --git a/drivers/media/media-devnode.c b/drivers/media/media-devnode.c
new file mode 100644
index 000..6f5558c
--- /dev/null
+++ b/drivers/media/media-devnode.c
@@ -0,0 +1,326 @@
+/*
+ * Media device node
+ *
+ * Generic media device node infrastructure to register and unregister
+ * character devices using a dynamic major number and proper reference
+ * counting.
+ *
+ * Copyright 2010 Laurent Pinchart laurent.pinch...@ideasonboard.com
+ *
+ * Based on drivers/media/video/v4l2_dev.c code authored by
+ *
+ * Mauro Carvalho Chehab mche...@infradead.org (version 2)
+ * Alan Cox, a...@lxorguk.ukuu.org.uk (version 1)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ */
+
+#include linux/errno.h
+#include linux/init.h
+#include linux/module.h
+#include linux/kernel.h
+#include linux/kmod.h
+#include linux/slab.h
+#include linux/mm.h
+#include linux/smp_lock.h
+#include linux/string.h
+#include linux/types.h
+#include linux/uaccess.h
+#include asm/system.h
+
+#include media/media-devnode.h
+
+#define MEDIA_NUM_DEVICES 256
+#define MEDIA_NAME media
+
+static dev_t media_dev_t;
+
+/*
+ * sysfs stuff
+ */
+
+static ssize_t show_name(struct device *cd,
+struct device_attribute *attr, char *buf)
+{
+ struct media_devnode *mdev = to_media_devnode(cd);
+
+ return sprintf(buf, %.*s\n, (int)sizeof(mdev-name), mdev-name);
+}
+
+static struct device_attribute media_devnode_attrs[] = {
+ __ATTR(name, S_IRUGO, show_name, NULL),
+ __ATTR_NULL
+};
+
+/*
+ * Active devices
+ */
+static DEFINE_MUTEX(media_devnode_lock);
+static DECLARE_BITMAP(media_devnode_nums, MEDIA_NUM_DEVICES);
+
+/* Called when the last user of the media device exits. */
+static void media_devnode_release(struct device *cd)
+{
+ struct media_devnode *mdev = to_media_devnode(cd);
+
+ mutex_lock(media_devnode_lock);
+
+ /* Delete the cdev on this minor as well */
+ cdev_del(mdev-cdev);
+
+ /* Mark device node number as free */
+ clear_bit(mdev-minor, media_devnode_nums);
+
+ mutex_unlock(media_devnode_lock);
+
+ /* Release media_devnode and perform other cleanups as needed. */
+ if (mdev-release)
+ mdev-release(mdev);
+}
+
+static struct class media_class = {
+ .name = MEDIA_NAME,
+ .dev_attrs = media_devnode_attrs,
+};
+
+static ssize_t media_read(struct file *filp, char __user *buf,
+ size_t sz, loff_t *off)
+{
+ struct media_devnode *mdev = media_devnode_data(filp);
+
+ if (!mdev-fops-read)
+ return -EINVAL;
+ if (!media_devnode_is_registered(mdev))
+ return -EIO;
+ return mdev-fops-read(filp, buf, sz, off);
+}
+
+static ssize_t media_write(struct file *filp, const char __user *buf,
+ size_t sz, loff_t *off)
+{
+ struct media_devnode *mdev = media_devnode_data(filp);
+
+ if (!mdev-fops-write)
+ return -EINVAL;
+ if (!media_devnode_is_registered(mdev))
+ return -EIO;
+ return mdev-fops-write(filp, buf, sz, off);
+}
+
+static unsigned int media_poll(struct file *filp,
+ struct poll_table_struct *poll)
+{
+ struct media_devnode *mdev = media_devnode_data(filp);
+
+ if (!mdev-fops-poll || !media_devnode_is_registered(mdev))
+ return DEFAULT_POLLMASK;
+ return mdev-fops-poll(filp, poll);
+}
+
+static long media_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+ struct
