iio: buffer: introduce support for attaching more IIO buffers

With this change, calling iio_device_attach_buffer() will actually attach
more buffers.
Right now this doesn't do any validation of whether a buffer is attached
twice; maybe that can be added later (if needed). Attaching a buffer more
than once should yield noticeably bad results.

The first buffer is the legacy buffer, so a reference is kept to it.

At this point, accessing the data for the extra buffers (that are added
after the first one) isn't possible yet.

The iio_device_attach_buffer() is also changed to return an error code,
which for now is -ENOMEM if the array could not be realloc-ed for more
buffers.
To adapt to this new change iio_device_attach_buffer() is called last in
all place where it's called. The realloc failure is a bit difficult to
handle during un-managed calls when unwinding, so it's better to have this
as the last error in the setup_buffer calls.

At this point, no driver should call iio_device_attach_buffer() directly,
it should call one of the {devm_}iio_triggered_buffer_setup() or
devm_iio_kfifo_buffer_setup() or devm_iio_dmaengine_buffer_setup()
functions. This makes iio_device_attach_buffer() a bit easier to handle.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20210215104043.91251-20-alexandru.ardelean@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index b96acfe13e92..1645c739c44f 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -1585,7 +1585,7 @@ static void iio_dev_release(struct device *device)
 	iio_device_unregister_eventset(indio_dev);
 	iio_device_unregister_sysfs(indio_dev);
 
-	iio_buffer_put(indio_dev->buffer);
+	iio_buffers_put(indio_dev);
 
 	ida_simple_remove(&iio_ida, indio_dev->id);
 	kfree(iio_dev_opaque);
@@ -1862,7 +1862,7 @@ int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod)
 
 	iio_device_register_debugfs(indio_dev);
 
-	ret = iio_buffer_alloc_sysfs_and_mask(indio_dev);
+	ret = iio_buffers_alloc_sysfs_and_mask(indio_dev);
 	if (ret) {
 		dev_err(indio_dev->dev.parent,
 			"Failed to create buffer sysfs interfaces\n");
@@ -1888,12 +1888,12 @@ 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;
 
-	if (indio_dev->buffer)
+	if (iio_dev_opaque->attached_buffers_cnt)
 		cdev_init(&indio_dev->chrdev, &iio_buffer_fileops);
 	else if (iio_dev_opaque->event_interface)
 		cdev_init(&indio_dev->chrdev, &iio_event_fileops);
 
-	if (indio_dev->buffer || iio_dev_opaque->event_interface) {
+	if (iio_dev_opaque->attached_buffers_cnt || iio_dev_opaque->event_interface) {
 		indio_dev->dev.devt = MKDEV(MAJOR(iio_devt), indio_dev->id);
 		indio_dev->chrdev.owner = this_mod;
 	}
@@ -1912,7 +1912,7 @@ error_unreg_eventset:
 error_free_sysfs:
 	iio_device_unregister_sysfs(indio_dev);
 error_buffer_free_sysfs:
-	iio_buffer_free_sysfs_and_mask(indio_dev);
+	iio_buffers_free_sysfs_and_mask(indio_dev);
 error_unreg_debugfs:
 	iio_device_unregister_debugfs(indio_dev);
 	return ret;
@@ -1946,7 +1946,7 @@ void iio_device_unregister(struct iio_dev *indio_dev)
 
 	mutex_unlock(&indio_dev->info_exist_lock);
 
-	iio_buffer_free_sysfs_and_mask(indio_dev);
+	iio_buffers_free_sysfs_and_mask(indio_dev);
 }
 EXPORT_SYMBOL(iio_device_unregister);