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Subject[PATCH v6 3/6] iio: core: register chardev only if needed
Date
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,
+ .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);

--
2.17.1
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