[PATCH v3 06/11] iio: core: merge buffer/ & scan_elements/ attributes

From: Alexandru Ardelean
Date: Mon Feb 01 2021 - 10:28:39 EST

With this change, we create a new directory for the IIO device called
buffer0, under which both the old buffer/ and scan_elements/ are stored.

This is done to simplify the addition of multiple IIO buffers per IIO
device. Otherwise we would need to add a bufferX/ and scan_elementsX/
directory for each IIO buffer.
With the current way of storing attribute groups, we can't have directories
stored under each other (i.e. scan_elements/ under buffer/), so the best
approach moving forward is to merge their attributes.

The old/legacy buffer/ & scan_elements/ groups are not stored on the opaque
IIO device object. This way the IIO buffer can have just a single
attribute_group object, saving a bit of memory when adding multiple IIO
buffers.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx>
---
drivers/iio/industrialio-buffer.c | 111 +++++++++++++++++++++++-------
include/linux/iio/buffer_impl.h | 9 +--
include/linux/iio/iio-opaque.h | 4 ++
3 files changed, 93 insertions(+), 31 deletions(-)

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 23f22be62cc7..f82decf92b7c 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -1252,8 +1252,68 @@ static struct attribute *iio_buffer_attrs[] = {
&dev_attr_data_available.attr,
};

+static int iio_buffer_register_legacy_sysfs_groups(struct iio_dev *indio_dev,
+ struct attribute **buffer_attrs,
+ int buffer_attrcount,
+ int scan_el_attrcount)
+{
+ struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
+ struct attribute_group *group;
+ int ret;
+
+ group = &iio_dev_opaque->legacy_buffer_group;
+
+ group->attrs = kcalloc(buffer_attrcount + 1,
+ sizeof(struct attribute *), GFP_KERNEL);
+ if (!group->attrs)
+ return -ENOMEM;
+
+ memcpy(group->attrs, buffer_attrs,
+ buffer_attrcount * sizeof(struct attribute *));
+ group->name = "buffer";
+
+ ret = iio_device_register_sysfs_group(indio_dev, group);
+ if (ret)
+ goto error_free_buffer_attrs;
+
+ group = &iio_dev_opaque->legacy_scan_el_group;
+
+ group->attrs = kcalloc(scan_el_attrcount + 1,
+ sizeof(struct attribute *), GFP_KERNEL);
+ if (!group->attrs) {
+ ret = -ENOMEM;
+ goto error_free_buffer_attrs;
+ }
+
+ memcpy(group->attrs, &buffer_attrs[buffer_attrcount],
+ scan_el_attrcount * sizeof(struct attribute *));
+ group->name = "scan_elements";
+
+ ret = iio_device_register_sysfs_group(indio_dev, group);
+ if (ret)
+ goto error_free_scan_el_attrs;
+
+ return 0;
+
+error_free_buffer_attrs:
+ kfree(iio_dev_opaque->legacy_buffer_group.attrs);
+error_free_scan_el_attrs:
+ kfree(iio_dev_opaque->legacy_scan_el_group.attrs);
+
+ return ret;
+}
+
+void iio_buffer_unregister_legacy_sysfs_groups(struct iio_dev *indio_dev)
+{
+ struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
+
+ kfree(iio_dev_opaque->legacy_buffer_group.attrs);
+ kfree(iio_dev_opaque->legacy_scan_el_group.attrs);
+}
+
static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
- struct iio_dev *indio_dev)
+ struct iio_dev *indio_dev,
+ int index)
{
struct iio_dev_attr *p;
struct attribute **attr;
@@ -1294,8 +1354,8 @@ static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
}
}

- attr = kcalloc(buffer_attrcount + ARRAY_SIZE(iio_buffer_attrs) + 1,
- sizeof(struct attribute *), GFP_KERNEL);
+ attrn = buffer_attrcount + scan_el_attrcount + ARRAY_SIZE(iio_buffer_attrs);
+ attr = kcalloc(attrn + 1, sizeof(struct attribute *), GFP_KERNEL);
if (!attr) {
ret = -ENOMEM;
goto error_free_scan_mask;
@@ -1313,37 +1373,36 @@ static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
sizeof(struct attribute *) * buffer_attrcount);

buffer_attrcount += ARRAY_SIZE(iio_buffer_attrs);
- attr[buffer_attrcount] = NULL;

- buffer->buffer_group.name = "buffer";
- buffer->buffer_group.attrs = attr;
+ attrn = buffer_attrcount;

- ret = iio_device_register_sysfs_group(indio_dev, &buffer->buffer_group);
- if (ret)
+ list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
+ attr[attrn++] = &p->dev_attr.attr;
+
+ buffer->buffer_group.name = kasprintf(GFP_KERNEL, "buffer%d", index);
+ if (!buffer->buffer_group.name)
goto error_free_buffer_attrs;

- buffer->scan_el_group.name = iio_scan_elements_group_name;
+ buffer->buffer_group.attrs = attr;

- buffer->scan_el_group.attrs = kcalloc(scan_el_attrcount + 1,
- sizeof(buffer->scan_el_group.attrs[0]),
- GFP_KERNEL);
- if (buffer->scan_el_group.attrs == NULL) {
- ret = -ENOMEM;
- goto error_free_scan_mask;
- }
- attrn = 0;
+ ret = iio_device_register_sysfs_group(indio_dev, &buffer->buffer_group);
+ if (ret)
+ goto error_free_buffer_attr_group_name;

- list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
- buffer->scan_el_group.attrs[attrn++] = &p->dev_attr.attr;
+ /* we only need to link the legacy buffer groups for the first buffer */
+ if (index > 0)
+ return 0;

- ret = iio_device_register_sysfs_group(indio_dev, &buffer->scan_el_group);
+ ret = iio_buffer_register_legacy_sysfs_groups(indio_dev, attr,
+ buffer_attrcount,
+ scan_el_attrcount);
if (ret)
- goto error_free_scan_el_attrs;
+ goto error_free_buffer_attr_group_name;

return 0;

-error_free_scan_el_attrs:
- kfree(buffer->scan_el_group.attrs);
+error_free_buffer_attr_group_name:
+ kfree(buffer->buffer_group.name);
error_free_buffer_attrs:
kfree(buffer->buffer_group.attrs);
error_free_scan_mask:
@@ -1372,14 +1431,14 @@ 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);
+ return __iio_buffer_alloc_sysfs_and_mask(buffer, indio_dev, 0);
}

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);
- kfree(buffer->scan_el_group.attrs);
iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
}

@@ -1390,6 +1449,8 @@ void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev)
if (!buffer)
return;

+ iio_buffer_unregister_legacy_sysfs_groups(indio_dev);
+
__iio_buffer_free_sysfs_and_mask(buffer);
}

diff --git a/include/linux/iio/buffer_impl.h b/include/linux/iio/buffer_impl.h
index a63dc07b7350..3e555e58475b 100644
--- a/include/linux/iio/buffer_impl.h
+++ b/include/linux/iio/buffer_impl.h
@@ -100,14 +100,11 @@ struct iio_buffer {
/* @scan_el_dev_attr_list: List of scan element related attributes. */
struct list_head scan_el_dev_attr_list;

- /* @buffer_group: Attributes of the buffer group. */
- struct attribute_group buffer_group;
-
/*
- * @scan_el_group: Attribute group for those attributes not
- * created from the iio_chan_info array.
+ * @buffer_group: Attributes of the new buffer group.
+ * Includes scan elements attributes.
*/
- struct attribute_group scan_el_group;
+ struct attribute_group buffer_group;

/* @attrs: Standard attributes of the buffer. */
const struct attribute **attrs;
diff --git a/include/linux/iio/iio-opaque.h b/include/linux/iio/iio-opaque.h
index 8ba13a5c7af6..3e4c3cd248fd 100644
--- a/include/linux/iio/iio-opaque.h
+++ b/include/linux/iio/iio-opaque.h
@@ -14,6 +14,8 @@
* @ioctl_handlers: ioctl handlers registered with the core handler
* @groups: attribute groups
* @groupcounter: index of next attribute group
+ * @legacy_scan_el_group: attribute group for legacy scan elements attribute group
+ * @legacy_buffer_el_group: attribute group for legacy buffer attributes group
* @debugfs_dentry: device specific debugfs dentry
* @cached_reg_addr: cached register address for debugfs reads
* @read_buf: read buffer to be used for the initial reg read
@@ -28,6 +30,8 @@ struct iio_dev_opaque {
struct list_head ioctl_handlers;
const struct attribute_group **groups;
int groupcounter;
+ struct attribute_group legacy_scan_el_group;
+ struct attribute_group legacy_buffer_group;
#if defined(CONFIG_DEBUG_FS)
struct dentry *debugfs_dentry;
unsigned cached_reg_addr;
--
2.17.1