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Subject[PATCH v3 10/11] iio: buffer: introduce support for attaching more IIO buffers
Date
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.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
---
drivers/iio/industrialio-buffer.c | 80 +++++++++++++++++++++++++------
include/linux/iio/buffer.h | 4 +-
include/linux/iio/buffer_impl.h | 3 ++
include/linux/iio/iio-opaque.h | 4 ++
4 files changed, 74 insertions(+), 17 deletions(-)

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 692f721588e2..a69bb705d173 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -1445,11 +1445,21 @@ static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
return ret;
}

+static void __iio_buffer_free_sysfs_and_mask(struct iio_buffer *buffer)
+{
+ bitmap_free(buffer->scan_mask);
+ kfree(buffer->buffer_group.name);
+ kfree(buffer->buffer_group.attrs);
+ iio_free_chan_devattr_list(&buffer->buffer_attr_list);
+}
+
int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
{
+ struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
struct iio_buffer *buffer = indio_dev->buffer;
const struct iio_chan_spec *channels;
- int i;
+ int unwind_idx;
+ int ret, i;

channels = indio_dev->channels;
if (channels) {
@@ -1463,27 +1473,45 @@ int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
if (!buffer)
return 0;

- return __iio_buffer_alloc_sysfs_and_mask(buffer, indio_dev, 0);
-}
+ for (i = 0; i < iio_dev_opaque->attached_buffers_cnt; i++) {
+ buffer = iio_dev_opaque->attached_buffers[i];
+ ret = __iio_buffer_alloc_sysfs_and_mask(buffer, indio_dev, i);
+ if (ret) {
+ unwind_idx = i;
+ goto error_unwind_sysfs_and_mask;
+ }
+ }

-static void __iio_buffer_free_sysfs_and_mask(struct iio_buffer *buffer)
-{
- bitmap_free(buffer->scan_mask);
- kfree(buffer->buffer_group.name);
- kfree(buffer->buffer_group.attrs);
- iio_free_chan_devattr_list(&buffer->buffer_attr_list);
+ return 0;
+
+error_unwind_sysfs_and_mask:
+ for (; unwind_idx >= 0; unwind_idx--) {
+ buffer = iio_dev_opaque->attached_buffers[unwind_idx];
+ __iio_buffer_free_sysfs_and_mask(buffer);
+ }
+ kfree(iio_dev_opaque->attached_buffers);
+ iio_dev_opaque->attached_buffers = NULL;
+ return ret;
}

void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev)
{
+ struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
struct iio_buffer *buffer = indio_dev->buffer;
+ int i;

if (!buffer)
return;

iio_buffer_unregister_legacy_sysfs_groups(indio_dev);

- __iio_buffer_free_sysfs_and_mask(buffer);
+ for (i = iio_dev_opaque->attached_buffers_cnt - 1; i >= 0; i--) {
+ buffer = iio_dev_opaque->attached_buffers[i];
+ __iio_buffer_free_sysfs_and_mask(buffer);
+ }
+
+ kfree(iio_dev_opaque->attached_buffers);
+ iio_dev_opaque->attached_buffers = NULL;
}

/**
@@ -1601,13 +1629,35 @@ EXPORT_SYMBOL_GPL(iio_buffer_put);
* @indio_dev: The device the buffer should be attached to
* @buffer: The buffer to attach to the device
*
+ * Return 0 if successful, negative if error.
+ *
* This function attaches a buffer to a IIO device. The buffer stays attached to
- * the device until the device is freed. The function should only be called at
- * most once per device.
+ * the device until the device is freed. For legacy reasons, the first attached
+ * buffer will also be assigned to 'indio_dev->buffer'.
*/
-void iio_device_attach_buffer(struct iio_dev *indio_dev,
- struct iio_buffer *buffer)
+int iio_device_attach_buffer(struct iio_dev *indio_dev,
+ struct iio_buffer *buffer)
{
- indio_dev->buffer = iio_buffer_get(buffer);
+ struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
+ struct iio_buffer **new, **old = iio_dev_opaque->attached_buffers;
+ unsigned int cnt = iio_dev_opaque->attached_buffers_cnt;
+
+ cnt++;
+
+ new = krealloc(old, sizeof(*new) * cnt, GFP_KERNEL);
+ if (!new)
+ return -ENOMEM;
+ iio_dev_opaque->attached_buffers = new;
+
+ buffer = iio_buffer_get(buffer);
+
+ /* first buffer is legacy; attach it to the IIO device directly */
+ if (!indio_dev->buffer)
+ indio_dev->buffer = buffer;
+
+ iio_dev_opaque->attached_buffers[cnt - 1] = buffer;
+ iio_dev_opaque->attached_buffers_cnt = cnt;
+
+ return 0;
}
EXPORT_SYMBOL_GPL(iio_device_attach_buffer);
diff --git a/include/linux/iio/buffer.h b/include/linux/iio/buffer.h
index 8febc23f5f26..b6928ac5c63d 100644
--- a/include/linux/iio/buffer.h
+++ b/include/linux/iio/buffer.h
@@ -41,7 +41,7 @@ static inline int iio_push_to_buffers_with_timestamp(struct iio_dev *indio_dev,
bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
const unsigned long *mask);

-void iio_device_attach_buffer(struct iio_dev *indio_dev,
- struct iio_buffer *buffer);
+int iio_device_attach_buffer(struct iio_dev *indio_dev,
+ struct iio_buffer *buffer);

#endif /* _IIO_BUFFER_GENERIC_H_ */
diff --git a/include/linux/iio/buffer_impl.h b/include/linux/iio/buffer_impl.h
index 41044320e581..768b90c64412 100644
--- a/include/linux/iio/buffer_impl.h
+++ b/include/linux/iio/buffer_impl.h
@@ -112,6 +112,9 @@ struct iio_buffer {
/* @demux_bounce: Buffer for doing gather from incoming scan. */
void *demux_bounce;

+ /* @attached_entry: Entry in the devices list of buffers attached by the driver. */
+ struct list_head attached_entry;
+
/* @buffer_list: Entry in the devices list of current buffers. */
struct list_head buffer_list;

diff --git a/include/linux/iio/iio-opaque.h b/include/linux/iio/iio-opaque.h
index 3e4c3cd248fd..c909835b6247 100644
--- a/include/linux/iio/iio-opaque.h
+++ b/include/linux/iio/iio-opaque.h
@@ -7,6 +7,8 @@
* struct iio_dev_opaque - industrial I/O device opaque information
* @indio_dev: public industrial I/O device information
* @event_interface: event chrdevs associated with interrupt lines
+ * @attached_buffers: array of buffers statically attached by the driver
+ * @attached_buffers_cnt: number of buffers in the array of statically attached buffers
* @buffer_list: list of all buffers currently attached
* @channel_attr_list: keep track of automatically created channel
* attributes
@@ -24,6 +26,8 @@
struct iio_dev_opaque {
struct iio_dev indio_dev;
struct iio_event_interface *event_interface;
+ struct iio_buffer **attached_buffers;
+ unsigned int attached_buffers_cnt;
struct list_head buffer_list;
struct list_head channel_attr_list;
struct attribute_group chan_attr_group;
--
2.17.1
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