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iio: trigger: allow immutable triggers to be assigned

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There are times when an assigned trigger to a device shouldn't ever
change after intialization.

Examples of this being used is when an provider device has a trigger
that is assigned to an ADC, which uses it populate data into a callback
buffer.

Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Matt Ranostay
2016-09-02 23:36:15 -07:00
committed by Jonathan Cameron
parent a5c8b11a36
commit c8cdf70890
3 changed files with 31 additions and 0 deletions
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20
drivers/iio/industrialio-trigger.c
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@@ -119,6 +119,22 @@ void iio_trigger_unregister(struct iio_trigger *trig_info)
}
EXPORT_SYMBOL(iio_trigger_unregister);
int iio_trigger_set_immutable(struct iio_dev *indio_dev, struct iio_trigger *trig)
{
if (!indio_dev || !trig)
return -EINVAL;
mutex_lock(&indio_dev->mlock);
WARN_ON(indio_dev->trig_readonly);
indio_dev->trig = iio_trigger_get(trig);
indio_dev->trig_readonly = true;
mutex_unlock(&indio_dev->mlock);
return 0;
}
EXPORT_SYMBOL(iio_trigger_set_immutable);
/* Search for trigger by name, assuming iio_trigger_list_lock held */
static struct iio_trigger *__iio_trigger_find_by_name(const char *name)
{
@@ -384,6 +400,10 @@ static ssize_t iio_trigger_write_current(struct device *dev,
mutex_unlock(&indio_dev->mlock);
return -EBUSY;
}
if (indio_dev->trig_readonly) {
mutex_unlock(&indio_dev->mlock);
return -EPERM;
}
mutex_unlock(&indio_dev->mlock);
trig = iio_trigger_find_by_name(buf, len);