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SubjectRe: [PATCH v6 3/6] iio: core: register chardev only if needed
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On Sun, 2020-05-03 at 16:39 +0100, Jonathan Cameron wrote:
> [External]
>
> On Mon, 27 Apr 2020 16:10:57 +0300
> Alexandru Ardelean <alexandru.ardelean@analog.com> wrote:
>
> > The final intent is to localize all buffer ops into the
> > industrialio-buffer.c file, to be able to add support for multiple buffers
> > per IIO device.
> >
> > We only need a chardev if we need to support buffers and/or events.
> >
> > With this change, a chardev will be created only if an IIO buffer is
> > attached OR an event_interface is configured.
> >
> > Otherwise, no chardev will be created, and the IIO device will get
> > registered with the 'device_add()' call.
> >
> > Quite a lot of IIO devices don't really need a chardev, so this is a minor
> > improvement to the IIO core, as the IIO device will take up (slightly)
> > fewer resources.
> >
> > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
> > ---
> > drivers/iio/industrialio-core.c | 25 ++++++++++++++++++++++---
> > 1 file changed, 22 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-
> > core.c
> > index 32c489139cd2..51e279c60793 100644
> > --- a/drivers/iio/industrialio-core.c
> > +++ b/drivers/iio/industrialio-core.c
> > @@ -1682,6 +1682,15 @@ static int iio_check_unique_scan_index(struct iio_dev
> > *indio_dev)
> >
> > static const struct iio_buffer_setup_ops noop_ring_setup_ops;
> >
> > +static const struct file_operations iio_event_fileops = {
> > + .owner = THIS_MODULE,
> > + .llseek = noop_llseek,
> > + .unlocked_ioctl = iio_event_ioctl_wrapper,
>
> Unfortunately this doesn't exist until the next patch...

crap;
i copied this from the wrong place when i re-ordered this, and forgot to run a
build on each patchset

will fix

>
> > + .compat_ioctl = compat_ptr_ioctl,
> > + .open = iio_chrdev_open,
> > + .release = iio_chrdev_release,
> > +};
> > +
> > int __iio_device_register(struct iio_dev *indio_dev, struct module
> > *this_mod)
> > {
> > int ret;
> > @@ -1732,11 +1741,18 @@ int __iio_device_register(struct iio_dev *indio_dev,
> > struct module *this_mod)
> > indio_dev->setup_ops == NULL)
> > indio_dev->setup_ops = &noop_ring_setup_ops;
> >
> > - cdev_init(&indio_dev->chrdev, &iio_buffer_fileops);
> > + if (indio_dev->buffer)
> > + cdev_init(&indio_dev->chrdev, &iio_buffer_fileops);
> > + else if (indio_dev->event_interface)
> > + cdev_init(&indio_dev->chrdev, &iio_event_fileops);
> >
> > indio_dev->chrdev.owner = this_mod;
> >
> > - ret = cdev_device_add(&indio_dev->chrdev, &indio_dev->dev);
> > + if (indio_dev->buffer || indio_dev->event_interface)
> > + ret = cdev_device_add(&indio_dev->chrdev, &indio_dev->dev);
> > + else
> > + ret = device_add(&indio_dev->dev);
> > +
> > if (ret < 0)
> > goto error_unreg_eventset;
> >
> > @@ -1760,7 +1776,10 @@ EXPORT_SYMBOL(__iio_device_register);
> > **/
> > void iio_device_unregister(struct iio_dev *indio_dev)
> > {
> > - cdev_device_del(&indio_dev->chrdev, &indio_dev->dev);
> > + if (indio_dev->buffer || indio_dev->event_interface)
> > + cdev_device_del(&indio_dev->chrdev, &indio_dev->dev);
> > + else
> > + device_del(&indio_dev->dev);
> >
> > mutex_lock(&indio_dev->info_exist_lock);
> >
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