Re: [PATCH 07/18] software_node: Add support for fwnode_graph*() family of functions

[Dan Scally <djrscally@xxxxxxxxx>]

Hi Laurent

On 30/11/2020 16:25, Laurent Pinchart wrote:
> Hi Daniel and Heikki,
>
> Thank you for the patch.
>
> On Mon, Nov 30, 2020 at 01:31:18PM +0000, Daniel Scally wrote:
>> From: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
>>
>> From: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
>>
> There seems to be one From: line too many. You can drop the one in the
> commit message, git-format-patch will add it automatically.
Ah! Thanks, sorry about that
>> This implements the remaining .graph_* callbacks in the
>> fwnode operations vector for the software nodes. That makes
> s/vector/structure/ ?
Yeah, sure.
>> the fwnode_graph*() functions available in the drivers also
>> when software nodes are used.
>>
>> The implementation tries to mimic the "OF graph" as much as
>> possible, but there is no support for the "reg" device
>> property. The ports will need to have the index in their
>> name which starts with "port" (for example "port0", "port1",
>> ...) and endpoints will use the index of the software node
>> that is given to them during creation. The port nodes can
>> also be grouped under a specially named "ports" subnode,
>> just like in DT, if necessary.
> I'm not very familiar with swnodes, but could we name ports port@n
> instead of portn to mimic OF nodes ?
Yes, I don't see any reason why not.
>
>> The remote-endpoints are reference properties under the
>> endpoint nodes that are named "remote-endpoint".
>>
>> Signed-off-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
>> Co-developed-by: Daniel Scally <djrscally@xxxxxxxxx>
>> Signed-off-by: Daniel Scally <djrscally@xxxxxxxxx>
>> ---
>> changes since RFC v3:
>> 	- Simplified software_node_get_next_endpoint() a little
>> 	- Squared away references in software_node_get_next_endpoint()
>> 	and swnode_graph_find_next_port(), since they were affected by
>> 	the change to the earlier patch that had *get_next_child() also
>> 	put the previous reference.
>> 	- Dropped Andy's R-b, since the code changed.
>> changes in RFC v3:
>> 	- removed software_node_device_is_available
>> 	- moved the change to software_node_get_next_child to a separate
>> 	patch
>> 	- switched to use fwnode_handle_put() in graph_get_next_endpoint()
>> 	instead of software_node_put()
>>
>> changes in RFC v2:
>> 	- added software_node_device_is_available
>> 	- altered software_node_get_next_child to get references
>> 	- altered software_node_get_next_endpoint to release references
>> 	to ports and avoid passing invalid combinations of swnodes to
>> 	software_node_get_next_child
>> 	- altered swnode_graph_find_next_port to release port rather than
>> 	old
>>
>>  drivers/base/swnode.c | 110 +++++++++++++++++++++++++++++++++++++++++-
>>  1 file changed, 109 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
>> index 9bd0bb77ad5b..0c7a8d6b9ea8 100644
>> --- a/drivers/base/swnode.c
>> +++ b/drivers/base/swnode.c
>> @@ -540,6 +540,110 @@ software_node_get_reference_args(const struct fwnode_handle *fwnode,
>>  	return 0;
>>  }
>>  
>> +static struct fwnode_handle *
>> +swnode_graph_find_next_port(const struct fwnode_handle *parent,
>> +			    struct fwnode_handle *port)
>> +{
>> +	struct fwnode_handle *old = port;
>> +
>> +	while ((port = software_node_get_next_child(parent, old))) {
>> +		if (!strncmp(to_swnode(port)->node->name, "port", 4))
>> +			return port;
>> +		old = port;
>> +	}
>> +
>> +	return NULL;
>> +}
>> +
>> +static struct fwnode_handle *
>> +software_node_graph_get_next_endpoint(const struct fwnode_handle *fwnode,
>> +				      struct fwnode_handle *endpoint)
>> +{
>> +	struct swnode *swnode = to_swnode(fwnode);
>> +	struct fwnode_handle *old = endpoint;
>> +	struct fwnode_handle *parent;
>> +	struct fwnode_handle *port;
>> +
>> +	if (!swnode)
>> +		return NULL;
>> +
>> +	if (endpoint) {
>> +		port = software_node_get_parent(endpoint);
>> +		parent = software_node_get_parent(port);
>> +	} else {
>> +		parent = software_node_get_named_child_node(fwnode, "ports");
>> +		if (!parent)
>> +			parent = software_node_get(&swnode->fwnode);
>> +
>> +		port = swnode_graph_find_next_port(parent, NULL);
>> +	}
>> +
>> +	for (; port; port = swnode_graph_find_next_port(parent, port)) {
>> +		endpoint = software_node_get_next_child(port, old);
>> +		if (endpoint) {
>> +			fwnode_handle_put(port);
>> +			break;
>> +		}
>> +
>> +		/* No more endpoints for that port, so stop passing old */
>> +		old = NULL;
>> +	}
>> +
>> +	fwnode_handle_put(parent);
>> +
>> +	return endpoint;
>> +}
>> +
>> +static struct fwnode_handle *
>> +software_node_graph_get_remote_endpoint(const struct fwnode_handle *fwnode)
>> +{
>> +	struct swnode *swnode = to_swnode(fwnode);
>> +	const struct software_node_ref_args *ref;
>> +	const struct property_entry *prop;
>> +
>> +	if (!swnode)
>> +		return NULL;
>> +
>> +	prop = property_entry_get(swnode->node->properties, "remote-endpoint");
>> +	if (!prop || prop->type != DEV_PROP_REF || prop->is_inline)
>> +		return NULL;
>> +
>> +	ref = prop->pointer;
>> +
>> +	return software_node_get(software_node_fwnode(ref[0].node));
>> +}
>> +
>> +static struct fwnode_handle *
>> +software_node_graph_get_port_parent(struct fwnode_handle *fwnode)
>> +{
>> +	struct swnode *swnode = to_swnode(fwnode);
>> +	struct fwnode_handle *parent;
>> +
>> +	if (!strcmp(swnode->parent->node->name, "ports"))
>> +		parent = &swnode->parent->parent->fwnode;
>> +	else
>> +		parent = &swnode->parent->fwnode;
>> +
>> +	return software_node_get(parent);
>> +}
>> +
>> +static int
>> +software_node_graph_parse_endpoint(const struct fwnode_handle *fwnode,
>> +				   struct fwnode_endpoint *endpoint)
>> +{
>> +	struct swnode *swnode = to_swnode(fwnode);
>> +	int ret;
>> +
>> +	ret = kstrtou32(swnode->parent->node->name + 4, 10, &endpoint->port);
> If we use port@, s/4/5/. But I suppose we also want to support the case
> where a single port is used, with its name set to "port" ? The logic
> would then need to be a tad more complex. Not sure if the consistency is
> worth the additional complexity, up to you.
I'm conflicted; consistency is good but in my mind keeping the name as
"port@0" for a single port rather than dropping the suffix is the better
approach anyway.
>> +	if (ret)
>> +		return ret;
>> +
>> +	endpoint->id = swnode->id;
>> +	endpoint->local_fwnode = fwnode;
>> +
>> +	return 0;
>> +}
>> +
>>  static const struct fwnode_operations software_node_ops = {
>>  	.get = software_node_get,
>>  	.put = software_node_put,
>> @@ -551,7 +655,11 @@ static const struct fwnode_operations software_node_ops = {
>>  	.get_parent = software_node_get_parent,
>>  	.get_next_child_node = software_node_get_next_child,
>>  	.get_named_child_node = software_node_get_named_child_node,
>> -	.get_reference_args = software_node_get_reference_args
>> +	.get_reference_args = software_node_get_reference_args,
>> +	.graph_get_next_endpoint = software_node_graph_get_next_endpoint,
>> +	.graph_get_remote_endpoint = software_node_graph_get_remote_endpoint,
>> +	.graph_get_port_parent = software_node_graph_get_port_parent,
>> +	.graph_parse_endpoint = software_node_graph_parse_endpoint,
>>  };
>>  
>>  /* -------------------------------------------------------------------------- */