[RFC PATCH 12/14] iio: buffer: symlink the scan_elements dir back into IIO device's dir

Alexandru Ardelean
2020-05-08T13:54:34Z

WIP

Need to explicitly create the scan_elements dir to symlink it.
Admittedly we could try to use some kernfs logic to dig out the kobject of
the 'scan_elements' group, it doesn't seem to be done outside of the fs/
kernel directory.

We need to use the sysfs_() function suite, and that means creating it by
hand after the IIO buffer device was created and added so that we have a
parent kobject to attach this folder to.

After we create it by hand there is a kobject to which to symlink this to
back to the IIO device.

IIO still broken
What's left:
- convert all external buffer attributes to unpack to IIO buffers and not
IIO devices
- symlink the chardev of the first IIO buffer device to the IIO device

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
---
drivers/iio/industrialio-buffer.c | 149 ++++++++++++++++++++++++------
include/linux/iio/buffer_impl.h | 7 +-
2 files changed, 122 insertions(+), 34 deletions(-)

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 6c35de7ebd9e..b14281442387 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -1310,15 +1310,11 @@ static struct attribute *iio_buffer_attrs[] = {
&dev_attr_data_available.attr,
};

-static int iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer)
+static int iio_buffer_alloc_sysfs(struct iio_buffer *buffer)
{
- struct iio_dev *indio_dev = buffer->indio_dev;
- struct iio_dev_attr *p;
struct attribute **attr;
- int ret, i, attrn, attrcount;
- const struct iio_chan_spec *channels;
+ int attrcount = 0;

- attrcount = 0;
if (buffer->attrs) {
while (buffer->attrs[attrcount] != NULL)
attrcount++;
@@ -1346,7 +1342,60 @@ static int iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer)

buffer->groups[0] = &buffer->buffer_group;

- attrcount = 0;
+ return 0;
+}
+
+static ssize_t iio_scan_el_dir_show(struct kobject *kobj,
+ struct attribute *attr, char *buf)
+{
+ struct device_attribute *dattr =
+ container_of(attr, struct device_attribute, attr);
+ struct iio_buffer *buffer =
+ container_of(kobj, struct iio_buffer, scan_el_dir);
+
+ if (!dattr->show)
+ return -EIO;
+
+ return dattr->show(&buffer->dev, dattr, buf);
+}
+
+static ssize_t iio_scan_el_dir_store(struct kobject *kobj,
+ struct attribute *attr,
+ const char *buf, size_t len)
+{
+ struct device_attribute *dattr =
+ container_of(attr, struct device_attribute, attr);
+ struct iio_buffer *buffer =
+ container_of(kobj, struct iio_buffer, scan_el_dir);
+
+ if (!dattr->store)
+ return -EIO;
+
+ return dattr->store(&buffer->dev, dattr, buf, len);
+}
+
+static struct sysfs_ops iio_scan_el_dir_ops = {
+ .show = iio_scan_el_dir_show,
+ .store = iio_scan_el_dir_store,
+};
+
+static void iio_buffer_dir_noop_release(struct kobject *kobj)
+{
+ /* nothing to do yet */
+}
+
+static struct kobj_type iio_scan_el_dir_ktype = {
+ .release = iio_buffer_dir_noop_release,
+ .sysfs_ops = &iio_scan_el_dir_ops,
+};
+
+static int iio_buffer_alloc_scan_sysfs(struct iio_buffer *buffer)
+{
+ struct iio_dev *indio_dev = buffer->indio_dev;
+ struct iio_dev_attr *p;
+ int ret, i;
+ const struct iio_chan_spec *channels;
+
INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
channels = indio_dev->channels;
if (channels) {
@@ -1359,7 +1408,6 @@ static int iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer)
&channels[i]);
if (ret < 0)
goto error_cleanup_dynamic;
- attrcount += ret;
if (channels[i].type == IIO_TIMESTAMP)
indio_dev->scan_index_timestamp =
channels[i].scan_index;
@@ -1370,37 +1418,52 @@ static int iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer)
goto error_cleanup_dynamic;
}

- buffer->scan_el_group.name = "scan_elements";
-
- buffer->scan_el_group.attrs = kcalloc(attrcount + 1,
- sizeof(buffer->scan_el_group.attrs[0]),
- GFP_KERNEL);
- if (buffer->scan_el_group.attrs == NULL) {
- ret = -ENOMEM;
+ ret = kobject_init_and_add(&buffer->scan_el_dir,
+ &iio_scan_el_dir_ktype, &buffer->dev.kobj,
+ "scan_elements");
+ if (ret)
goto error_free_scan_mask;
- }
- attrn = 0;

- list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
- buffer->scan_el_group.attrs[attrn++] = &p->dev_attr.attr;
- buffer->groups[1] = &buffer->scan_el_group;
+ i = 0;
+ list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l) {
+ ret = sysfs_create_file(&buffer->scan_el_dir,
+ &p->dev_attr.attr);
+ if (ret)
+ goto error_remove_scan_el_dir;
+ i++;
+ }

return 0;

+error_remove_scan_el_dir:
+ list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l) {
+ if (i == 0)
+ break;
+ sysfs_remove_file(&buffer->scan_el_dir, &p->dev_attr.attr);
+ i--;
+ }
+ kobject_put(&buffer->scan_el_dir);
error_free_scan_mask:
iio_buffer_free_scanmask(buffer);
error_cleanup_dynamic:
iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
- kfree(buffer->buffer_group.attrs);

return ret;
}

-static void iio_buffer_free_sysfs_and_mask(struct iio_buffer *buffer)
+static void iio_buffer_free_sysfs(struct iio_buffer *buffer)
{
iio_buffer_free_scanmask(buffer);
kfree(buffer->buffer_group.attrs);
- kfree(buffer->scan_el_group.attrs);
+}
+
+static void iio_buffer_free_scan_sysfs(struct iio_buffer *buffer)
+{
+ struct iio_dev_attr *p;
+
+ list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
+ sysfs_remove_file(&buffer->scan_el_dir, &p->dev_attr.attr);
+ kobject_put(&buffer->scan_el_dir);
iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
}

@@ -1410,7 +1473,7 @@ static int iio_device_buffer_init(struct iio_dev *indio_dev,
{
int ret;

- ret = iio_buffer_alloc_sysfs_and_mask(buffer);
+ ret = iio_buffer_alloc_sysfs(buffer);
if (ret)
return ret;

@@ -1430,12 +1493,18 @@ static int iio_device_buffer_init(struct iio_dev *indio_dev,
if (ret)
goto error_free_chrdev_id;

+ ret = iio_buffer_alloc_scan_sysfs(buffer);
+ if (ret)
+ goto error_cdev_device_del;
+
return 0;

+error_cdev_device_del:
+ cdev_device_del(&buffer->chrdev, &buffer->dev);
error_free_chrdev_id:
iio_device_free_chrdev_id(&buffer->dev);
error_free_sysfs_and_mask:
- iio_buffer_free_sysfs_and_mask(buffer);
+ iio_buffer_free_sysfs(buffer);
return ret;
}

@@ -1444,13 +1513,33 @@ void iio_device_buffer_cleanup(struct iio_buffer *buffer)
if (!buffer)
return;

- iio_buffer_free_sysfs_and_mask(buffer);
+ iio_buffer_free_scan_sysfs(buffer);

cdev_device_del(&buffer->chrdev, &buffer->dev);

+ iio_buffer_free_sysfs(buffer);
+
iio_device_free_chrdev_id(&buffer->dev);
}

+static int iio_device_link_legacy_folders(struct iio_dev *indio_dev,
+ struct iio_buffer *buffer)
+{
+ int ret;
+
+ ret = sysfs_create_link(&indio_dev->dev.kobj,
+ &buffer->dev.kobj, "buffer");
+ if (ret)
+ return ret;
+
+ ret = sysfs_create_link(&indio_dev->dev.kobj,
+ &buffer->scan_el_dir, "scan_elements");
+ if (ret)
+ sysfs_remove_link(&indio_dev->dev.kobj, "buffer");
+
+ return ret;
+}
+
int iio_device_buffers_init(struct iio_dev *indio_dev)
{
struct iio_buffer *buffer = indio_dev->buffer;
@@ -1473,14 +1562,13 @@ int iio_device_buffers_init(struct iio_dev *indio_dev)
if (ret)
return ret;

- ret = sysfs_create_link(&indio_dev->dev.kobj,
- &buffer->dev.kobj, "buffer");
+ ret = iio_device_link_legacy_folders(indio_dev, buffer);
if (ret)
- goto error_cleanup_buffers;
+ goto error_buffers_cleanup;

return 0;

-error_cleanup_buffers:
+error_buffers_cleanup:
iio_device_buffer_cleanup(buffer);
return 0;
}
@@ -1490,6 +1578,7 @@ void iio_device_buffers_cleanup(struct iio_dev *indio_dev)
struct iio_buffer *buffer = indio_dev->buffer;

sysfs_remove_link(&indio_dev->dev.kobj, "buffer");
+ sysfs_remove_link(&indio_dev->dev.kobj, "scan_elements");

iio_device_buffer_cleanup(buffer);
}
diff --git a/include/linux/iio/buffer_impl.h b/include/linux/iio/buffer_impl.h
index eca3fe630230..e8203b6d51a1 100644
--- a/include/linux/iio/buffer_impl.h
+++ b/include/linux/iio/buffer_impl.h
@@ -107,7 +107,7 @@ struct iio_buffer {
/* @dev: underlying device object. */
struct device dev;

-#define IIO_BUFFER_MAX_GROUP 2
+#define IIO_BUFFER_MAX_GROUP 1
const struct attribute_group *groups[IIO_BUFFER_MAX_GROUP + 1];

/* @scan_timestamp: Does the scan mode include a timestamp. */
@@ -120,10 +120,9 @@ struct iio_buffer {
struct attribute_group buffer_group;

/*
- * @scan_el_group: Attribute group for those attributes not
- * created from the iio_chan_info array.
+ * @scan_el_dir: kobject for the 'scan_elements' directory
*/
- struct attribute_group scan_el_group;
+ struct kobject scan_el_dir;

/* @attrs: Standard attributes of the buffer. */
const struct attribute **attrs;
--
2.17.1