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path: root/drivers/media/video/v4l2-dev.c
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Diffstat (limited to 'drivers/media/video/v4l2-dev.c')
-rw-r--r--drivers/media/video/v4l2-dev.c154
1 files changed, 96 insertions, 58 deletions
diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index a7f1b69a7da..500cbe9891a 100644
--- a/drivers/media/video/v4l2-dev.c
+++ b/drivers/media/video/v4l2-dev.c
@@ -66,7 +66,49 @@ static struct device_attribute video_device_attrs[] = {
*/
static struct video_device *video_device[VIDEO_NUM_DEVICES];
static DEFINE_MUTEX(videodev_lock);
-static DECLARE_BITMAP(video_nums[VFL_TYPE_MAX], VIDEO_NUM_DEVICES);
+static DECLARE_BITMAP(devnode_nums[VFL_TYPE_MAX], VIDEO_NUM_DEVICES);
+
+/* Device node utility functions */
+
+/* Note: these utility functions all assume that vfl_type is in the range
+ [0, VFL_TYPE_MAX-1]. */
+
+#ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
+/* Return the bitmap corresponding to vfl_type. */
+static inline unsigned long *devnode_bits(int vfl_type)
+{
+ /* Any types not assigned to fixed minor ranges must be mapped to
+ one single bitmap for the purposes of finding a free node number
+ since all those unassigned types use the same minor range. */
+ int idx = (vfl_type > VFL_TYPE_VTX) ? VFL_TYPE_MAX - 1 : vfl_type;
+
+ return devnode_nums[idx];
+}
+#else
+/* Return the bitmap corresponding to vfl_type. */
+static inline unsigned long *devnode_bits(int vfl_type)
+{
+ return devnode_nums[vfl_type];
+}
+#endif
+
+/* Mark device node number vdev->num as used */
+static inline void devnode_set(struct video_device *vdev)
+{
+ set_bit(vdev->num, devnode_bits(vdev->vfl_type));
+}
+
+/* Mark device node number vdev->num as unused */
+static inline void devnode_clear(struct video_device *vdev)
+{
+ clear_bit(vdev->num, devnode_bits(vdev->vfl_type));
+}
+
+/* Try to find a free device node number in the range [from, to> */
+static inline int devnode_find(struct video_device *vdev, int from, int to)
+{
+ return find_next_zero_bit(devnode_bits(vdev->vfl_type), to, from);
+}
struct video_device *video_device_alloc(void)
{
@@ -119,8 +161,8 @@ static void v4l2_device_release(struct device *cd)
the release() callback. */
vdev->cdev = NULL;
- /* Mark minor as free */
- clear_bit(vdev->num, video_nums[vdev->vfl_type]);
+ /* Mark device node number as free */
+ devnode_clear(vdev);
mutex_unlock(&videodev_lock);
@@ -299,32 +341,28 @@ static const struct file_operations v4l2_fops = {
};
/**
- * get_index - assign stream number based on parent device
+ * get_index - assign stream index number based on parent device
* @vdev: video_device to assign index number to, vdev->parent should be assigned
- * @num: -1 if auto assign, requested number otherwise
*
* Note that when this is called the new device has not yet been registered
- * in the video_device array.
+ * in the video_device array, but it was able to obtain a minor number.
+ *
+ * This means that we can always obtain a free stream index number since
+ * the worst case scenario is that there are VIDEO_NUM_DEVICES - 1 slots in
+ * use of the video_device array.
*
- * Returns -ENFILE if num is already in use, a free index number if
- * successful.
+ * Returns a free index number.
*/
-static int get_index(struct video_device *vdev, int num)
+static int get_index(struct video_device *vdev)
{
/* This can be static since this function is called with the global
videodev_lock held. */
static DECLARE_BITMAP(used, VIDEO_NUM_DEVICES);
int i;
- if (num >= VIDEO_NUM_DEVICES) {
- printk(KERN_ERR "videodev: %s num is too large\n", __func__);
- return -EINVAL;
- }
-
- /* Some drivers do not set the parent. In that case always return
- num or 0. */
+ /* Some drivers do not set the parent. In that case always return 0. */
if (vdev->parent == NULL)
- return num >= 0 ? num : 0;
+ return 0;
bitmap_zero(used, VIDEO_NUM_DEVICES);
@@ -335,35 +373,23 @@ static int get_index(struct video_device *vdev, int num)
}
}
- if (num >= 0) {
- if (test_bit(num, used))
- return -ENFILE;
- return num;
- }
-
- i = find_first_zero_bit(used, VIDEO_NUM_DEVICES);
- return i == VIDEO_NUM_DEVICES ? -ENFILE : i;
+ return find_first_zero_bit(used, VIDEO_NUM_DEVICES);
}
-int video_register_device(struct video_device *vdev, int type, int nr)
-{
- return video_register_device_index(vdev, type, nr, -1);
-}
-EXPORT_SYMBOL(video_register_device);
-
/**
- * video_register_device_index - register video4linux devices
+ * video_register_device - register video4linux devices
* @vdev: video device structure we want to register
* @type: type of device to register
- * @nr: which device number (0 == /dev/video0, 1 == /dev/video1, ...
+ * @nr: which device node number (0 == /dev/video0, 1 == /dev/video1, ...
* -1 == first free)
- * @index: stream number based on parent device;
- * -1 if auto assign, requested number otherwise
+ * @warn_if_nr_in_use: warn if the desired device node number
+ * was already in use and another number was chosen instead.
*
- * The registration code assigns minor numbers based on the type
- * requested. -ENFILE is returned in all the device slots for this
- * category are full. If not then the minor field is set and the
- * driver initialize function is called (if non %NULL).
+ * The registration code assigns minor numbers and device node numbers
+ * based on the requested type and registers the new device node with
+ * the kernel.
+ * An error is returned if no free minor or device node number could be
+ * found, or if the registration of the device node failed.
*
* Zero is returned on success.
*
@@ -377,8 +403,8 @@ EXPORT_SYMBOL(video_register_device);
*
* %VFL_TYPE_RADIO - A radio card
*/
-int video_register_device_index(struct video_device *vdev, int type, int nr,
- int index)
+static int __video_register_device(struct video_device *vdev, int type, int nr,
+ int warn_if_nr_in_use)
{
int i = 0;
int ret;
@@ -421,7 +447,7 @@ int video_register_device_index(struct video_device *vdev, int type, int nr,
if (vdev->v4l2_dev && vdev->v4l2_dev->dev)
vdev->parent = vdev->v4l2_dev->dev;
- /* Part 2: find a free minor, kernel number and device index. */
+ /* Part 2: find a free minor, device node number and device index. */
#ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
/* Keep the ranges for the first four types for historical
* reasons.
@@ -452,21 +478,22 @@ int video_register_device_index(struct video_device *vdev, int type, int nr,
}
#endif
- /* Pick a minor number */
+ /* Pick a device node number */
mutex_lock(&videodev_lock);
- nr = find_next_zero_bit(video_nums[type], minor_cnt, nr == -1 ? 0 : nr);
+ nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt);
if (nr == minor_cnt)
- nr = find_first_zero_bit(video_nums[type], minor_cnt);
+ nr = devnode_find(vdev, 0, minor_cnt);
if (nr == minor_cnt) {
- printk(KERN_ERR "could not get a free kernel number\n");
+ printk(KERN_ERR "could not get a free device node number\n");
mutex_unlock(&videodev_lock);
return -ENFILE;
}
#ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES
- /* 1-on-1 mapping of kernel number to minor number */
+ /* 1-on-1 mapping of device node number to minor number */
i = nr;
#else
- /* The kernel number and minor numbers are independent */
+ /* The device node number and minor numbers are independent, so
+ we just find the first free minor number. */
for (i = 0; i < VIDEO_NUM_DEVICES; i++)
if (video_device[i] == NULL)
break;
@@ -478,17 +505,13 @@ int video_register_device_index(struct video_device *vdev, int type, int nr,
#endif
vdev->minor = i + minor_offset;
vdev->num = nr;
- set_bit(nr, video_nums[type]);
+ devnode_set(vdev);
+
/* Should not happen since we thought this minor was free */
WARN_ON(video_device[vdev->minor] != NULL);
- ret = vdev->index = get_index(vdev, index);
+ vdev->index = get_index(vdev);
mutex_unlock(&videodev_lock);
- if (ret < 0) {
- printk(KERN_ERR "%s: get_index failed\n", __func__);
- goto cleanup;
- }
-
/* Part 3: Initialize the character device */
vdev->cdev = cdev_alloc();
if (vdev->cdev == NULL) {
@@ -517,7 +540,7 @@ int video_register_device_index(struct video_device *vdev, int type, int nr,
vdev->dev.devt = MKDEV(VIDEO_MAJOR, vdev->minor);
if (vdev->parent)
vdev->dev.parent = vdev->parent;
- dev_set_name(&vdev->dev, "%s%d", name_base, nr);
+ dev_set_name(&vdev->dev, "%s%d", name_base, vdev->num);
ret = device_register(&vdev->dev);
if (ret < 0) {
printk(KERN_ERR "%s: device_register failed\n", __func__);
@@ -527,6 +550,10 @@ int video_register_device_index(struct video_device *vdev, int type, int nr,
reference to the device goes away. */
vdev->dev.release = v4l2_device_release;
+ if (nr != -1 && nr != vdev->num && warn_if_nr_in_use)
+ printk(KERN_WARNING "%s: requested %s%d, got %s%d\n",
+ __func__, name_base, nr, name_base, vdev->num);
+
/* Part 5: Activate this minor. The char device can now be used. */
mutex_lock(&videodev_lock);
video_device[vdev->minor] = vdev;
@@ -537,13 +564,24 @@ cleanup:
mutex_lock(&videodev_lock);
if (vdev->cdev)
cdev_del(vdev->cdev);
- clear_bit(vdev->num, video_nums[type]);
+ devnode_clear(vdev);
mutex_unlock(&videodev_lock);
/* Mark this video device as never having been registered. */
vdev->minor = -1;
return ret;
}
-EXPORT_SYMBOL(video_register_device_index);
+
+int video_register_device(struct video_device *vdev, int type, int nr)
+{
+ return __video_register_device(vdev, type, nr, 1);
+}
+EXPORT_SYMBOL(video_register_device);
+
+int video_register_device_no_warn(struct video_device *vdev, int type, int nr)
+{
+ return __video_register_device(vdev, type, nr, 0);
+}
+EXPORT_SYMBOL(video_register_device_no_warn);
/**
* video_unregister_device - unregister a video4linux device