openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

V4L/DVB (12724): v4l2-dev: add simple wrapper functions around the devnode numbers 

There are some subtle differences in the way the devnode numbers are
handled depending on whether the FIXED_MINOR_RANGES config option is
set. Add some simple wrapper functions to handle that correctly.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Hans Verkuil 2009-09-07 03:40:24 -03:00 committed by Mauro Carvalho Chehab
parent 581644d9c9
commit 5062cb70c8
1 changed files with 48 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
drivers/media/video/v4l2-dev.c
View File

@ -68,6 +68,48 @@ static struct video_device *video_device[VIDEO_NUM_DEVICES];
static DEFINE_MUTEX(videodev_lock);
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)
{
return kzalloc(sizeof(struct video_device), GFP_KERNEL);
@ -120,7 +162,7 @@ static void v4l2_device_release(struct device *cd)
vdev->cdev = NULL;
/* Mark device node number as free */
clear_bit(vdev->num, devnode_nums[vdev->vfl_type]);
devnode_clear(vdev);
mutex_unlock(&videodev_lock);
@ -435,9 +477,9 @@ int video_register_device(struct video_device *vdev, int type, int nr)
/* Pick a device node number */
mutex_lock(&videodev_lock);
nr = find_next_zero_bit(devnode_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(devnode_nums[type], minor_cnt);
nr = devnode_find(vdev, 0, minor_cnt);
if (nr == minor_cnt) {
printk(KERN_ERR "could not get a free device node number\n");
mutex_unlock(&videodev_lock);
@ -460,7 +502,8 @@ int video_register_device(struct video_device *vdev, int type, int nr)
#endif
vdev->minor = i + minor_offset;
vdev->num = nr;
set_bit(nr, devnode_nums[type]);
devnode_set(vdev);
/* Should not happen since we thought this minor was free */
WARN_ON(video_device[vdev->minor] != NULL);
vdev->index = get_index(vdev);
@ -514,7 +557,7 @@ int video_register_device(struct video_device *vdev, int type, int nr)
mutex_lock(&videodev_lock);
if (vdev->cdev)
cdev_del(vdev->cdev);
clear_bit(vdev->num, devnode_nums[type]);
devnode_clear(vdev);
mutex_unlock(&videodev_lock);
/* Mark this video device as never having been registered. */
vdev->minor = -1;