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V4L/DVB (11671): v4l2: add v4l2_device_set_name()

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Add a utility function that can be used to setup the v4l2_device's name
field in a standard manner.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Hans Verkuil 2009-05-02 10:12:50 -03:00 committed by Mauro Carvalho Chehab
parent 416a7aa883
commit 102e781364
3 changed files with 42 additions and 0 deletions
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5
Documentation/video4linux/v4l2-framework.txt
View File

@ -89,6 +89,11 @@ from dev (driver name followed by the bus_id, to be precise). If you set it
up before calling v4l2_device_register then it will be untouched. If dev is
NULL, then you *must* setup v4l2_dev->name before calling v4l2_device_register.
You can use v4l2_device_set_name() to set the name based on a driver name and
a driver-global atomic_t instance. This will generate names like ivtv0, ivtv1,
etc. If the name ends with a digit, then it will insert a dash: cx18-0,
cx18-1, etc. This function returns the instance number.
The first 'dev' argument is normally the struct device pointer of a pci_dev,
usb_interface or platform_device. It is rare for dev to be NULL, but it happens
with ISA devices or when one device creates multiple PCI devices, thus making

16
drivers/media/video/v4l2-device.c
View File

@ -49,6 +49,22 @@ int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)
}
EXPORT_SYMBOL_GPL(v4l2_device_register);
int v4l2_device_set_name(struct v4l2_device *v4l2_dev, const char *basename,
atomic_t *instance)
{
int num = atomic_inc_return(instance) - 1;
int len = strlen(basename);
if (basename[len - 1] >= '0' && basename[len - 1] <= '9')
snprintf(v4l2_dev->name, sizeof(v4l2_dev->name),
"%s-%d", basename, num);
else
snprintf(v4l2_dev->name, sizeof(v4l2_dev->name),
"%s%d", basename, num);
return num;
}
EXPORT_SYMBOL_GPL(v4l2_device_set_name);
void v4l2_device_disconnect(struct v4l2_device *v4l2_dev)
{
if (v4l2_dev->dev) {

21
include/media/v4l2-device.h
View File

@ -53,10 +53,31 @@ struct v4l2_device {
dev may be NULL in rare cases (ISA devices). In that case you
must fill in the v4l2_dev->name field before calling this function. */
int __must_check v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev);
/* Optional function to initialize the name field of struct v4l2_device using
the driver name and a driver-global atomic_t instance.
This function will increment the instance counter and returns the instance
value used in the name.
Example:
static atomic_t drv_instance = ATOMIC_INIT(0);
...
instance = v4l2_device_set_name(&v4l2_dev, "foo", &drv_instance);
The first time this is called the name field will be set to foo0 and
this function returns 0. If the name ends with a digit (e.g. cx18),
then the name will be set to cx18-0 since cx180 looks really odd. */
int v4l2_device_set_name(struct v4l2_device *v4l2_dev, const char *basename,
atomic_t *instance);
/* Set v4l2_dev->dev to NULL. Call when the USB parent disconnects.
Since the parent disappears this ensures that v4l2_dev doesn't have an
invalid parent pointer. */
void v4l2_device_disconnect(struct v4l2_device *v4l2_dev);
/* Unregister all sub-devices and any other resources related to v4l2_dev. */
void v4l2_device_unregister(struct v4l2_device *v4l2_dev);