Introduce device_add_of_disk() as a variant of device_add_disk() that
permits to pass and attach a fwnode to disk dev.

This variant can be useful for eMMC that might have the partition table
for the disk defined in DT. A parser can later make use of the attached
fwnode to parse the related table and init the hardcoded partition for
the disk.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
---
 block/genhd.c          | 21 +++++++++++++++++++--
 include/linux/blkdev.h |  3 +++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index 1c05dd4c6980..0fc595895f1d 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -391,8 +391,9 @@ int disk_scan_partitions(struct gendisk *disk, blk_mode_t mode)
  * This function registers the partitioning information in @disk
  * with the kernel.
  */
-int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
-				 const struct attribute_group **groups)
+static int __device_add_disk(struct device *parent, struct gendisk *disk,
+			     const struct attribute_group **groups,
+			     struct fwnode_handle *fwnode)
 
 {
 	struct device *ddev = disk_to_dev(disk);
@@ -452,6 +453,8 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
 	ddev->parent = parent;
 	ddev->groups = groups;
 	dev_set_name(ddev, "%s", disk->disk_name);
+	if (fwnode)
+		device_set_node(ddev, fwnode);
 	if (!(disk->flags & GENHD_FL_HIDDEN))
 		ddev->devt = MKDEV(disk->major, disk->first_minor);
 	ret = device_add(ddev);
@@ -553,8 +556,22 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
 		elevator_exit(disk->queue);
 	return ret;
 }
+
+int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
+				 const struct attribute_group **groups)
+{
+	return __device_add_disk(parent, disk, groups, NULL);
+}
 EXPORT_SYMBOL(device_add_disk);
 
+int __must_check device_add_of_disk(struct device *parent, struct gendisk *disk,
+				    const struct attribute_group **groups,
+				    struct fwnode_handle *fwnode)
+{
+	return __device_add_disk(parent, disk, groups, fwnode);
+}
+EXPORT_SYMBOL(device_add_of_disk);
+
 static void blk_report_disk_dead(struct gendisk *disk, bool surprise)
 {
 	struct block_device *bdev;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index bf1aa951fda2..7d41f35f1065 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -725,6 +725,9 @@ static inline unsigned int blk_queue_depth(struct request_queue *q)
 #define for_each_bio(_bio)		\
 	for (; _bio; _bio = _bio->bi_next)
 
+int __must_check device_add_of_disk(struct device *parent, struct gendisk *disk,
+				    const struct attribute_group **groups,
+				    struct fwnode_handle *fwnode);
 int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
 				 const struct attribute_group **groups);
 static inline int __must_check add_disk(struct gendisk *disk)
-- 
2.45.2

Thanks,

this looks much better.  A few minor nitpicks, though:

> -int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
> -				 const struct attribute_group **groups)
> +static int __device_add_disk(struct device *parent, struct gendisk *disk,
> +			     const struct attribute_group **groups,
> +			     struct fwnode_handle *fwnode)

I don't think we need a separate helper if device_add_disk simply
wraps the OF version by passing a NULL fwnode.

> +int __must_check device_add_of_disk(struct device *parent, struct gendisk *disk,
> +				    const struct attribute_group **groups,
> +				    struct fwnode_handle *fwnode)
> +{
> +	return __device_add_disk(parent, disk, groups, fwnode);
> +}

I'd name this as add_disk_fwnode as the of in device_add_of_disk
reads as in add the device of the disk, and the fwnode is what gets
passed.  The device_ is a bit redundant and just there for historic
reasons as the original add_disk predates the device model.

Can you also add a kerneldoc comment for the new helper?

> +EXPORT_SYMBOL(device_add_of_disk);

EXPORT_SYMBO_GPL, please.

On Wed, Oct 02, 2024 at 01:40:58AM -0700, Christoph Hellwig wrote:
> Thanks,
> 
> this looks much better.  A few minor nitpicks, though:
>

Very happy you like it, yes I wasn't sure what was the correct way to
introduce the helper. If you notice in the blkdev.h we have also add_disk()
that is a static inline wrapper for device_add_disk().

Wonder if device_add_disk() should have the same treatement? No idea if
it would cause problem with symbol with external modules, that is why I
used the wrapper.

> > -int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
> > -				 const struct attribute_group **groups)
> > +static int __device_add_disk(struct device *parent, struct gendisk *disk,
> > +			     const struct attribute_group **groups,
> > +			     struct fwnode_handle *fwnode)
> 
> I don't think we need a separate helper if device_add_disk simply
> wraps the OF version by passing a NULL fwnode.
> 
> > +int __must_check device_add_of_disk(struct device *parent, struct gendisk *disk,
> > +				    const struct attribute_group **groups,
> > +				    struct fwnode_handle *fwnode)
> > +{
> > +	return __device_add_disk(parent, disk, groups, fwnode);
> > +}
> 
> I'd name this as add_disk_fwnode as the of in device_add_of_disk
> reads as in add the device of the disk, and the fwnode is what gets
> passed.  The device_ is a bit redundant and just there for historic
> reasons as the original add_disk predates the device model.
> 
> Can you also add a kerneldoc comment for the new helper?
> 

sure! I will wait the usual 24h to respin this.

> > +EXPORT_SYMBOL(device_add_of_disk);
> 
> EXPORT_SYMBO_GPL, please.
> 

ack.

-- 
	Ansuel

On Wed, Oct 02, 2024 at 10:46:46AM +0200, Christian Marangi wrote:
> Very happy you like it, yes I wasn't sure what was the correct way to
> introduce the helper. If you notice in the blkdev.h we have also add_disk()
> that is a static inline wrapper for device_add_disk().
> 
> Wonder if device_add_disk() should have the same treatement? No idea if
> it would cause problem with symbol with external modules, that is why I
> used the wrapper.

We could make it an inline wrapper, but it's not in a high performance
path so there isn't really much of a point in doing so.  I don't
remember why it was done for add_disk.