From: Alexandru Ardelean <alexandru.ardelean@analog.com>
To: <linux-kernel@vger.kernel.org>, <linux-iio@vger.kernel.org>
Cc: <lars@metafoo.de>, <Michael.Hennerich@analog.com>,
<jic23@kernel.org>, <nuno.sa@analog.com>,
<dragos.bogdan@analog.com>,
Alexandru Ardelean <alexandru.ardelean@analog.com>
Subject: [PATCH v2 01/12] iio: core: register chardev only if needed
Date: Fri, 22 Jan 2021 17:57:54 +0200 [thread overview]
Message-ID: <20210122155805.83012-2-alexandru.ardelean@analog.com> (raw)
In-Reply-To: <20210122155805.83012-1-alexandru.ardelean@analog.com>
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.
In order to not create a chardev, we mostly just need to not initialize the
indio_dev->dev.devt field. If that is un-initialized, cdev_device_add()
behaves like device_add().
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
---
drivers/iio/industrialio-core.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index 7db761afa578..0a6fd299a978 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -1761,6 +1761,15 @@ static const struct file_operations iio_buffer_fileops = {
.release = iio_chrdev_release,
};
+static const struct file_operations iio_event_fileops = {
+ .owner = THIS_MODULE,
+ .llseek = noop_llseek,
+ .unlocked_ioctl = iio_ioctl,
+ .compat_ioctl = compat_ptr_ioctl,
+ .open = iio_chrdev_open,
+ .release = iio_chrdev_release,
+};
+
static int iio_check_unique_scan_index(struct iio_dev *indio_dev)
{
int i, j;
@@ -1788,6 +1797,7 @@ static const struct iio_buffer_setup_ops noop_ring_setup_ops;
int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod)
{
+ struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
int ret;
if (!indio_dev->info)
@@ -1805,9 +1815,6 @@ int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod)
if (ret < 0)
return ret;
- /* configure elements for the chrdev */
- indio_dev->dev.devt = MKDEV(MAJOR(iio_devt), indio_dev->id);
-
iio_device_register_debugfs(indio_dev);
ret = iio_buffer_alloc_sysfs_and_mask(indio_dev);
@@ -1836,9 +1843,15 @@ 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 (iio_dev_opaque->event_interface)
+ cdev_init(&indio_dev->chrdev, &iio_event_fileops);
- indio_dev->chrdev.owner = this_mod;
+ if (indio_dev->buffer || iio_dev_opaque->event_interface) {
+ indio_dev->dev.devt = MKDEV(MAJOR(iio_devt), indio_dev->id);
+ indio_dev->chrdev.owner = this_mod;
+ }
ret = cdev_device_add(&indio_dev->chrdev, &indio_dev->dev);
if (ret < 0)
--
2.17.1
next prev parent reply other threads:[~2021-01-22 17:31 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-22 15:57 [PATCH v2 00/12] iio: core,buffer: add support for multiple IIO buffers per IIO device Alexandru Ardelean
2021-01-22 15:57 ` Alexandru Ardelean [this message]
2021-01-22 15:57 ` [PATCH v2 02/12] iio: buffer: add back-ref from iio_buffer to iio_dev Alexandru Ardelean
2021-01-22 15:57 ` [PATCH v2 03/12] iio: buffer: rework buffer & scan_elements dir creation Alexandru Ardelean
2021-01-22 15:57 ` [PATCH v2 04/12] iio: buffer: add index to the first IIO buffer dir and symlink it back Alexandru Ardelean
2021-01-22 15:57 ` [PATCH v2 05/12] iio: core: split __iio_device_attr_init() to init only the attr object Alexandru Ardelean
2021-01-22 15:57 ` [PATCH v2 06/12] iio: buffer: re-route scan_elements via it's kobj_type Alexandru Ardelean
2021-01-22 16:12 ` Alexandru Ardelean
2021-01-22 15:58 ` [PATCH v2 07/12] iio: buffer: re-route core buffer attributes via it's new kobj_type Alexandru Ardelean
2021-01-22 15:58 ` [PATCH v2 08/12] iio: buffer: add helper to get the IIO device to which a buffer belongs Alexandru Ardelean
2021-01-22 15:58 ` [PATCH v2 09/12] iio: re-route all buffer attributes through new buffer kobj_type Alexandru Ardelean
2021-01-22 15:58 ` [PATCH v2 10/12] iio: core: wrap iio device & buffer into struct for character devices Alexandru Ardelean
2021-01-22 15:58 ` [PATCH v2 11/12] iio: buffer: introduce support for attaching more IIO buffers Alexandru Ardelean
2021-01-22 15:58 ` [PATCH v2 12/12] iio: buffer: add ioctl() to support opening extra buffers for IIO device Alexandru Ardelean
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