Re: [PATCH v2] software_node: Add support for fwnode_graph*() family of functions

[Dan Scally <djrscally@gmail.com>]

Hi Sakari - thanks for the comments

On 16/09/2020 10:17, Sakari Ailus wrote:
> Moi Daniel and Heikki,
>
> On Wed, Sep 16, 2020 at 12:28:27AM +0100, Daniel Scally wrote:
>> From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
>>
>> This implements the remaining .graph_* callbacks in the
>> fwnode operations vector for the software nodes. That makes
>> 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.
>>
>> The remote-endpoints are reference properties under the
>> endpoint nodes that are named "remote-endpoint". 
>>
>> Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
>> Co-developed-by: Daniel Scally <djrscally@gmail.com>
>> Signed-off-by: Daniel Scally <djrscally@gmail.com>
>> ---
>> changes in 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 | 129 +++++++++++++++++++++++++++++++++++++++++-
>>  1 file changed, 127 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c
>> index 010828fc785b..d69034b807e3 100644
>> --- a/drivers/base/swnode.c
>> +++ b/drivers/base/swnode.c
>> @@ -363,6 +363,11 @@ static void software_node_put(struct fwnode_handle *fwnode)
>>  	kobject_put(&swnode->kobj);
>>  }
>>  
>> +static bool software_node_device_is_available(const struct fwnode_handle *fwnode)
>> +{
>> +	return is_software_node(fwnode);
> This basically tells whether the device is there. Are there software node
> based devices, i.e. do you need this?
>
> If you do really need this, then I guess this could just return true for
> now as if you somehow get here, the node is a software node anyway.

I do think its better to include it; I'm targeting using this with
ipu3-cio2; the cio2_parse_firmware() call there doesn't pass
FWNODE_GRAPH_DEVICE_DISABLED to fwnode_graph_get_endpoint_by_id() so
this function does need to exist to be found by that call (or else
cio2_parse_firmware() would need to pass that flag...but I don't know
the effect of doing that on devices that aren't using software nodes so
it didn't seem like a good idea). I can change it to return true though sure

>> +}
>> +
>>  static bool software_node_property_present(const struct fwnode_handle *fwnode,
>>  					   const char *propname)
>>  {
>> @@ -450,7 +455,7 @@ software_node_get_next_child(const struct fwnode_handle *fwnode,
>>  		c = list_next_entry(c, entry);
>>  	else
>>  		c = list_first_entry(&p->children, struct swnode, entry);
>> -	return &c->fwnode;
>> +	return software_node_get(&c->fwnode);
> This looks like a bugfix that probably should or could be backported. Could
> you make it a separate patch, with a Fixes: tag?
Yes, sure. That does change how some of the other code would need to
work though if this patch were applied but not the separated one. Sorry;
not sure what's the best way to proceed in that case. Should I just note
that this patch depends on the prior application of the separated one?
>
>>  }
>>  
>>  static struct fwnode_handle *
>> @@ -536,9 +541,125 @@ 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;
>> +		fwnode_handle_put(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_of_old;
>> +	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)) {
>> +
>> +		if (old) {
>> +			parent_of_old = software_node_get_parent(old);
>> +
>> +			if (parent_of_old != port)
>> +				old = NULL;
>> +
>> +			fwnode_handle_put(parent_of_old);
>> +		}
>> +
>> +		endpoint = software_node_get_next_child(port, old);
>> +		fwnode_handle_put(old);
>> +		if (endpoint)
>> +			break;
>> +
>> +		fwnode_handle_put(port);
>> +	}
>> +
>> +	fwnode_handle_put(port);
>> +	software_node_put(parent);
> This probably should be fwnode_handle_put() as well as this is basically
> corresponding the device (i.e. likely not a software node).
Yep good point, fwnode_handle_put() it is.
>> +
>> +	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 (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,
>> +	.device_is_available = software_node_device_is_available,
>>  	.property_present = software_node_property_present,
>>  	.property_read_int_array = software_node_read_int_array,
>>  	.property_read_string_array = software_node_read_string_array,
>> @@ -547,7 +668,11 @@ 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,
>>  };
>>  
>>  /* -------------------------------------------------------------------------- */