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authorbrandon@ifup.org <brandon@ifup.org>2008-06-20 22:58:53 -0300
committerMauro Carvalho Chehab <mchehab@infradead.org>2008-07-20 07:10:27 -0300
commit539a7555b31e65e66fb84c881d07d2bf18c974d0 (patch)
tree6986fc5c76388c2b07b15911eca0b52100d68f15 /drivers
parentbbfc4c234e240b67ccd9cdca72d76267bad0dc96 (diff)
V4L/DVB (8078): Introduce "index" attribute for persistent video4linux device nodes
A number of V4L drivers have a mod param to specify their preferred minors. This is because it is often desirable for applications to have a static /dev name for a particular device. However, using minors has several disadvantages: 1) the requested minor may already be taken 2) using a mod param is driver specific 3) it requires every driver to add a param 4) requires configuration by hand This patch introduces an "index" attribute that when combined with udev rules can create static device paths like this: /dev/v4l/by-path/pci-0000\:00\:1d.2-usb-0\:1\:1.0-video0 /dev/v4l/by-path/pci-0000\:00\:1d.2-usb-0\:1\:1.0-video1 /dev/v4l/by-path/pci-0000\:00\:1d.2-usb-0\:1\:1.0-video2 $ ls -la /dev/v4l/by-path/pci-0000\:00\:1d.2-usb-0\:1\:1.0-video0 lrwxrwxrwx 1 root root 12 2008-04-28 00:02 /dev/v4l/by-path/pci-0000:00:1d.2-usb-0:1:1.0-video0 -> ../../video1 These paths are steady across reboots and should be resistant to rearranging across Kernel versions. video_register_device_index is available to drivers to request a specific index number. Signed-off-by: Brandon Philips <bphilips@suse.de> Signed-off-by: Kees Cook <kees@outflux.net> Signed-off-by: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/media/video/videodev.c98
1 files changed, 96 insertions, 2 deletions
diff --git a/drivers/media/video/videodev.c b/drivers/media/video/videodev.c
index 6cf6ad7193d..9c539eb3381 100644
--- a/drivers/media/video/videodev.c
+++ b/drivers/media/video/videodev.c
@@ -372,6 +372,14 @@ EXPORT_SYMBOL(v4l_printk_ioctl);
* sysfs stuff
*/
+static ssize_t show_index(struct device *cd,
+ struct device_attribute *attr, char *buf)
+{
+ struct video_device *vfd = container_of(cd, struct video_device,
+ class_dev);
+ return sprintf(buf, "%i\n", vfd->index);
+}
+
static ssize_t show_name(struct device *cd,
struct device_attribute *attr, char *buf)
{
@@ -410,6 +418,7 @@ static void video_release(struct device *cd)
static struct device_attribute video_device_attrs[] = {
__ATTR(name, S_IRUGO, show_name, NULL),
+ __ATTR(index, S_IRUGO, show_index, NULL),
__ATTR_NULL
};
@@ -1900,8 +1909,82 @@ out:
}
EXPORT_SYMBOL(video_ioctl2);
+struct index_info {
+ struct device *dev;
+ unsigned int used[VIDEO_NUM_DEVICES];
+};
+
+static int __fill_index_info(struct device *cd, void *data)
+{
+ struct index_info *info = data;
+ struct video_device *vfd = container_of(cd, struct video_device,
+ class_dev);
+
+ if (info->dev == vfd->dev)
+ info->used[vfd->index] = 1;
+
+ return 0;
+}
+
+/**
+ * assign_index - assign stream number based on parent device
+ * @vdev: video_device to assign index number to, vdev->dev should be assigned
+ * @num: -1 if auto assign, requested number otherwise
+ *
+ *
+ * returns -ENFILE if num is already in use, a free index number if
+ * successful.
+ */
+static int get_index(struct video_device *vdev, int num)
+{
+ struct index_info *info;
+ int i;
+ int ret = 0;
+
+ if (num >= VIDEO_NUM_DEVICES)
+ return -EINVAL;
+
+ info = kzalloc(sizeof(*info), GFP_KERNEL);
+ if (!info)
+ return -ENOMEM;
+
+ info->dev = vdev->dev;
+
+ ret = class_for_each_device(&video_class, info,
+ __fill_index_info);
+
+ if (ret < 0)
+ goto out;
+
+ if (num >= 0) {
+ if (!info->used[num])
+ ret = num;
+ else
+ ret = -ENFILE;
+
+ goto out;
+ }
+
+ for (i = 0; i < VIDEO_NUM_DEVICES; i++) {
+ if (info->used[i])
+ continue;
+ ret = i;
+ goto out;
+ }
+
+out:
+ kfree(info);
+ return ret;
+}
+
static const struct file_operations video_fops;
+int video_register_device(struct video_device *vfd, int type, int nr)
+{
+ return video_register_device_index(vfd, type, nr, -1);
+}
+EXPORT_SYMBOL(video_register_device);
+
/**
* video_register_device - register video4linux devices
* @vfd: video device structure we want to register
@@ -1927,7 +2010,8 @@ static const struct file_operations video_fops;
* %VFL_TYPE_RADIO - A radio card
*/
-int video_register_device(struct video_device *vfd, int type, int nr)
+int video_register_device_index(struct video_device *vfd, int type, int nr,
+ int index)
{
int i=0;
int base;
@@ -1984,6 +2068,16 @@ int video_register_device(struct video_device *vfd, int type, int nr)
}
video_device[i]=vfd;
vfd->minor=i;
+
+ ret = get_index(vfd, index);
+ if (ret < 0) {
+ printk(KERN_ERR "%s: get_index failed\n",
+ __func__);
+ goto fail_minor;
+ }
+
+ vfd->index = ret;
+
mutex_unlock(&videodev_lock);
mutex_init(&vfd->lock);
@@ -2017,7 +2111,7 @@ fail_minor:
mutex_unlock(&videodev_lock);
return ret;
}
-EXPORT_SYMBOL(video_register_device);
+EXPORT_SYMBOL(video_register_device_index);
/**
* video_unregister_device - unregister a video4linux device