On 6/9/2016 5:13 PM, Adam Thomson wrote:
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 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 <adam.thomson.opensou...@diasemi.com>
Tested-by: Sathyanarayana Nujella <sathyanarayana.nuje...@intel.com>

For some reason that didn't make it into the linux-acpi list, or at least I can't see it there.

---

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/property.h |  3 +++
  4 files changed, 44 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index f38c21d..573b361 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 (!strcasecmp(to_of_node(child)->name, childname))

Why do you use strcasecmp() here?

+                               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;
+}

Is there any particular reason to introduce this function instead of doing the test in device_get_named_child_node() directly?

+
  static inline struct fwnode_handle *acpi_fwnode_handle(struct acpi_device 
*adev)
  {
        return &adev->fwnode;
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 288fac5..03039c4 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -568,6 +568,12 @@ static inline struct acpi_data_node 
*to_acpi_data_node(struct fwnode_handle *fwn
        return NULL;
  }

+static inline bool acpi_data_node_match(struct fwnode_handle *fwnode,
+                                       const char *name)
+{
+       return false;
+}
+
  static inline struct fwnode_handle *acpi_fwnode_handle(struct acpi_device 
*adev)
  {
        return NULL;
diff --git a/include/linux/property.h b/include/linux/property.h
index ecab11e..3a2f9ae 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -77,6 +77,9 @@ struct fwnode_handle *device_get_next_child_node(struct 
device *dev,
        for (child = device_get_next_child_node(dev, NULL); child;      \
             child = device_get_next_child_node(dev, child))

+struct fwnode_handle *device_get_named_child_node(struct device *dev,
+                                                 const char *childname);
+
  void fwnode_handle_put(struct fwnode_handle *fwnode);

  unsigned int device_get_child_node_count(struct device *dev);
--

Mika, Heikki, Andy, any feedback on this one?

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