On Tuesday, June 21, 2016 02:11:26 PM Mika Westerberg wrote:

On Mon, Jun 20, 2016 at 12:38:58PM +0100, Adam Thomson wrote:

quoted

For device nodes in both DT and ACPI, it possible to have named
child nodes which contain properties (an existing example being
gpio-leds). This adds a function to find a named child node for
a device which can be used by drivers for property retrieval.

For DT data node name matching, of_node_cmp() and similar functions
are made available outside of CONFIG_OF block so the new function
can reference these for DT and non-DT builds.

For ACPI data node name matching, a helper function is also added
which returns false if CONFIG_ACPI is not set, otherwise it
performs a string comparison on the data node name. This avoids
using the acpi_data_node struct for non CONFIG_ACPI builds,
which would otherwise cause a build failure.

Signed-off-by: Adam Thomson <redacted>
Tested-by: Sathyanarayana Nujella <redacted>
Acked-by: Rob Herring <robh@kernel.org>
---

Changes in v3:
 - Move of_*_cmp() functions in of.h outside of CONFIG_OF block so they are
   available for non-DT builds
 - In device_get_named_child_node(), use of_node_cmp() helper macro instead of
   strcasecmp() (node names not alway case insensitive, depending on platform).

Changes in v2:
 - Rebase to v4.7-rc1

 drivers/base/property.c  | 28 ++++++++++++++++++++++++++++
 include/acpi/acpi_bus.h  |  7 +++++++
 include/linux/acpi.h     |  6 ++++++
 include/linux/of.h       | 14 +++++++-------
 include/linux/property.h |  3 +++
 5 files changed, 51 insertions(+), 7 deletions(-)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index f38c21d..43a36d6 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c

@@ -888,6 +888,34 @@ struct fwnode_handle *device_get_next_child_node(struct device *dev,
 EXPORT_SYMBOL_GPL(device_get_next_child_node);

 /**
+ * device_get_named_child_node - Return first matching named child node handle
+ * @dev: Device to find the named child node for.
+ * @childname: String to match child node name against.
+ */
+struct fwnode_handle *device_get_named_child_node(struct device *dev,
+						  const char *childname)
+{
+	struct fwnode_handle *child;
+
+	/*
+	 * Find first matching named child node of this device.
+	 * For ACPI this will be a data only sub-node.
+	 */
+	device_for_each_child_node(dev, child) {
+		if (is_of_node(child)) {
+			if (!of_node_cmp(to_of_node(child)->name, childname))
+				return child;
+		} else if (is_acpi_data_node(child)) {
+			if (acpi_data_node_match(child, childname))
+				return child;
+		}
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(device_get_named_child_node);
+
+/**
  * fwnode_handle_put - Drop reference to a device node
  * @fwnode: Pointer to the device node to drop the reference to.
  *

diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 788c6c3..993bdd0 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h

@@ -420,6 +420,13 @@ static inline struct acpi_data_node *to_acpi_data_node(struct fwnode_handle *fwn
 		container_of(fwnode, struct acpi_data_node, fwnode) : NULL;
 }

+static inline bool acpi_data_node_match(struct fwnode_handle *fwnode,
+					const char *name)
+{
+	return is_acpi_data_node(fwnode) ?
+		(!strcasecmp(to_acpi_data_node(fwnode)->name, name)) : false;
+}

Looks fine to me.

One question - is it expected that matching ACPI data nodes is always
case insensitive?

That would not be a correct expectation in theory, although I don't think it
really matters in practice.

Thanks,
Rafael