In some cases multiple connections with the same connection id
needs to be resolved from a fwnode graph.
One such example is when separate hardware is used for performing muxing
and/or orientation switching of the SuperSpeed and SBU lines in a USB
Type-C connector. In this case the connector needs to belong to a graph
with multiple matching remote endpoints, and the Type-C controller needs
to be able to resolve them both.
Add a new API that allows this kind of lookup.
Signed-off-by: Bjorn Andersson <[email protected]>
---
Changes since v3:
- fwnode_connection_find_matches() should not adjust matches before calling
fwnode_devcon_matches()
- Replaced return from within the loops with break
- Changed "count >= matches_len && matches" to "matches && count >=
matches_len", to denote the significance of "matches"
Changes since v2:
- Allow the caller of the new api to pass a matches of NULL, to count possible
matches. I previously argued that this will cause memory leaks, but Andy
pointed out that this depends on the caller and the match function.
- Fixed spelling mistakes in commit message and kernel-doc.
- Use two "count" variables to make the math clearer.
Changes since v1:
- Iterator in fwnode_devcon_matches() is now unsigned.
- fwnode_handle_put() node for unavailable nodes.
- Extended commit message on the subject of supporting dynamically sized
"matches" array.
drivers/base/property.c | 109 +++++++++++++++++++++++++++++++++++++++
include/linux/property.h | 5 ++
2 files changed, 114 insertions(+)
diff --git a/drivers/base/property.c b/drivers/base/property.c
index c0e94cce9c29..7fccb0587855 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -1218,6 +1218,40 @@ fwnode_graph_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
return NULL;
}
+static unsigned int fwnode_graph_devcon_matches(struct fwnode_handle *fwnode,
+ const char *con_id, void *data,
+ devcon_match_fn_t match,
+ void **matches,
+ unsigned int matches_len)
+{
+ struct fwnode_handle *node;
+ struct fwnode_handle *ep;
+ unsigned int count = 0;
+ void *ret;
+
+ fwnode_graph_for_each_endpoint(fwnode, ep) {
+ if (matches && count >= matches_len) {
+ fwnode_handle_put(ep);
+ break;
+ }
+
+ node = fwnode_graph_get_remote_port_parent(ep);
+ if (!fwnode_device_is_available(node)) {
+ fwnode_handle_put(node);
+ continue;
+ }
+
+ ret = match(node, con_id, data);
+ fwnode_handle_put(node);
+ if (ret) {
+ if (matches)
+ matches[count] = ret;
+ count++;
+ }
+ }
+ return count;
+}
+
static void *
fwnode_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
void *data, devcon_match_fn_t match)
@@ -1240,6 +1274,37 @@ fwnode_devcon_match(struct fwnode_handle *fwnode, const char *con_id,
return NULL;
}
+static unsigned int fwnode_devcon_matches(struct fwnode_handle *fwnode,
+ const char *con_id, void *data,
+ devcon_match_fn_t match,
+ void **matches,
+ unsigned int matches_len)
+{
+ struct fwnode_handle *node;
+ unsigned int count = 0;
+ unsigned int i;
+ void *ret;
+
+ for (i = 0; ; i++) {
+ if (matches && count >= matches_len)
+ break;
+
+ node = fwnode_find_reference(fwnode, con_id, i);
+ if (IS_ERR(node))
+ break;
+
+ ret = match(node, NULL, data);
+ fwnode_handle_put(node);
+ if (ret) {
+ if (matches)
+ matches[count] = ret;
+ count++;
+ }
+ }
+
+ return count;
+}
+
/**
* fwnode_connection_find_match - Find connection from a device node
* @fwnode: Device node with the connection
@@ -1267,3 +1332,47 @@ void *fwnode_connection_find_match(struct fwnode_handle *fwnode,
return fwnode_devcon_match(fwnode, con_id, data, match);
}
EXPORT_SYMBOL_GPL(fwnode_connection_find_match);
+
+/**
+ * fwnode_connection_find_matches - Find connections from a device node
+ * @fwnode: Device node with the connection
+ * @con_id: Identifier for the connection
+ * @data: Data for the match function
+ * @match: Function to check and convert the connection description
+ * @matches: Array of pointers to fill with matches
+ * @matches_len: Length of @matches
+ *
+ * Find up to @matches_len connections with unique identifier @con_id between
+ * @fwnode and other device nodes. @match will be used to convert the
+ * connection description to data the caller is expecting to be returned
+ * through the @matches array.
+ * If @matches is NULL @matches_len is ignored and the total number of resolved
+ * matches is returned.
+ *
+ * Return: Number of matches resolved, or negative errno.
+ */
+int fwnode_connection_find_matches(struct fwnode_handle *fwnode,
+ const char *con_id, void *data,
+ devcon_match_fn_t match,
+ void **matches, unsigned int matches_len)
+{
+ unsigned int count_graph;
+ unsigned int count_ref;
+
+ if (!fwnode || !match)
+ return -EINVAL;
+
+ count_graph = fwnode_graph_devcon_matches(fwnode, con_id, data, match,
+ matches, matches_len);
+
+ if (matches) {
+ matches += count_graph;
+ matches_len -= count_graph;
+ }
+
+ count_ref = fwnode_devcon_matches(fwnode, con_id, data, match,
+ matches, matches_len);
+
+ return count_graph + count_ref;
+}
+EXPORT_SYMBOL_GPL(fwnode_connection_find_matches);
diff --git a/include/linux/property.h b/include/linux/property.h
index 4cd4b326941f..de7ff336d2c8 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -447,6 +447,11 @@ static inline void *device_connection_find_match(struct device *dev,
return fwnode_connection_find_match(dev_fwnode(dev), con_id, data, match);
}
+int fwnode_connection_find_matches(struct fwnode_handle *fwnode,
+ const char *con_id, void *data,
+ devcon_match_fn_t match,
+ void **matches, unsigned int matches_len);
+
/* -------------------------------------------------------------------------- */
/* Software fwnode support - when HW description is incomplete or missing */
--
2.33.1
On Sun, Mar 06, 2022 at 07:40:34PM -0800, Bjorn Andersson wrote:
> In some cases multiple connections with the same connection id
> needs to be resolved from a fwnode graph.
>
> One such example is when separate hardware is used for performing muxing
> and/or orientation switching of the SuperSpeed and SBU lines in a USB
> Type-C connector. In this case the connector needs to belong to a graph
> with multiple matching remote endpoints, and the Type-C controller needs
> to be able to resolve them both.
>
> Add a new API that allows this kind of lookup.
Thanks for the update!
First of all, I have noticed that subject misses the verb, something like Add
or Introduce.
...
> +/**
> + * fwnode_connection_find_matches - Find connections from a device node
> + * @fwnode: Device node with the connection
> + * @con_id: Identifier for the connection
> + * @data: Data for the match function
> + * @match: Function to check and convert the connection description
> + * @matches: Array of pointers to fill with matches
(Optional) array...
> + * @matches_len: Length of @matches
> + *
> + * Find up to @matches_len connections with unique identifier @con_id between
> + * @fwnode and other device nodes. @match will be used to convert the
> + * connection description to data the caller is expecting to be returned
> + * through the @matches array.
> + * If @matches is NULL @matches_len is ignored and the total number of resolved
> + * matches is returned.
I would require matches_len to be 0, see below.
> + * Return: Number of matches resolved, or negative errno.
> + */
> +int fwnode_connection_find_matches(struct fwnode_handle *fwnode,
> + const char *con_id, void *data,
> + devcon_match_fn_t match,
> + void **matches, unsigned int matches_len)
> +{
> + unsigned int count_graph;
> + unsigned int count_ref;
> +
> + if (!fwnode || !match)
> + return -EINVAL;
> +
> + count_graph = fwnode_graph_devcon_matches(fwnode, con_id, data, match,
> + matches, matches_len);
> + if (matches) {
> + matches += count_graph;
> + matches_len -= count_graph;
> + }
So, the valid case is matches != NULL and matches_len == 0. For example, when
we have run something previously on the buffer and it becomes full.
In this case we have carefully handle this case.
if (matches) {
matches += count_graph;
if (matches_len)
matches_len -= count_graph;
}
Seems it can be also
if (matches)
matches += count_graph;
if (matches_len)
matches_len -= count_graph;
That said, do we have a test cases for this?
> + count_ref = fwnode_devcon_matches(fwnode, con_id, data, match,
> + matches, matches_len);
> +
> + return count_graph + count_ref;
> +}
--
With Best Regards,
Andy Shevchenko
On Mon 07 Mar 02:05 PST 2022, Andy Shevchenko wrote:
> On Sun, Mar 06, 2022 at 07:40:34PM -0800, Bjorn Andersson wrote:
> > In some cases multiple connections with the same connection id
> > needs to be resolved from a fwnode graph.
> >
> > One such example is when separate hardware is used for performing muxing
> > and/or orientation switching of the SuperSpeed and SBU lines in a USB
> > Type-C connector. In this case the connector needs to belong to a graph
> > with multiple matching remote endpoints, and the Type-C controller needs
> > to be able to resolve them both.
> >
> > Add a new API that allows this kind of lookup.
>
> Thanks for the update!
>
> First of all, I have noticed that subject misses the verb, something like Add
> or Introduce.
>
Will update accordingly.
> ...
>
> > +/**
> > + * fwnode_connection_find_matches - Find connections from a device node
> > + * @fwnode: Device node with the connection
> > + * @con_id: Identifier for the connection
> > + * @data: Data for the match function
> > + * @match: Function to check and convert the connection description
> > + * @matches: Array of pointers to fill with matches
>
> (Optional) array...
>
Ditto.
> > + * @matches_len: Length of @matches
> > + *
> > + * Find up to @matches_len connections with unique identifier @con_id between
> > + * @fwnode and other device nodes. @match will be used to convert the
> > + * connection description to data the caller is expecting to be returned
> > + * through the @matches array.
>
> > + * If @matches is NULL @matches_len is ignored and the total number of resolved
> > + * matches is returned.
>
> I would require matches_len to be 0, see below.
>
> > + * Return: Number of matches resolved, or negative errno.
> > + */
> > +int fwnode_connection_find_matches(struct fwnode_handle *fwnode,
> > + const char *con_id, void *data,
> > + devcon_match_fn_t match,
> > + void **matches, unsigned int matches_len)
> > +{
> > + unsigned int count_graph;
> > + unsigned int count_ref;
> > +
> > + if (!fwnode || !match)
> > + return -EINVAL;
> > +
> > + count_graph = fwnode_graph_devcon_matches(fwnode, con_id, data, match,
> > + matches, matches_len);
>
> > + if (matches) {
> > + matches += count_graph;
> > + matches_len -= count_graph;
> > + }
>
> So, the valid case is matches != NULL and matches_len == 0. For example, when
> we have run something previously on the buffer and it becomes full.
>
> In this case we have carefully handle this case.
>
> if (matches) {
> matches += count_graph;
> if (matches_len)
> matches_len -= count_graph;
When matches is non-NULL, both the sub-functions are limited by
matches_len and as such count_graph <= matches_len.
As such matches_len >= 0.
In the event that the originally passed matches_len was 0, then
count_graph will be 0 and matches_len will remain 0.
I therefor don't see that this additional check changes things.
> }
>
> Seems it can be also
>
> if (matches)
> matches += count_graph;
>
> if (matches_len)
> matches_len -= count_graph;
We covered the case of matches && (matches_len || !matches_len) above.
For the case of !matches && matches_len, this added conditional would
cause matches_len to be extra ignored by keeping it at 0, but per
kernel-doc and implementation we ignore all other values already.
Note that this is in contrast from vsnprintf() where the code will
continue to produce results, only store the first "matches_len"
entires and return the final count.
Unfortunately we can't follow such semantics here, instead it is clearly
documented in the kernel-doc that @matches_len is ignored when @matches
is NULL.
So unless I'm missing something I don't see what you gain over keeping
the check on only matches.
>
> That said, do we have a test cases for this?
>
I looked briefly at adding some kunit tests for this, but was discourage
by the prospect of building up the graphs to run the tests against.
Regards,
Bjorn
> > + count_ref = fwnode_devcon_matches(fwnode, con_id, data, match,
> > + matches, matches_len);
> > +
> > + return count_graph + count_ref;
> > +}
>
> --
> With Best Regards,
> Andy Shevchenko
>
>