device property: Add function to search for named child of device

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 <Adam.Thomson.Opensource@diasemi.com>
Acked-by: Sathyanarayana Nujella <sathyanarayana.nujella@intel.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/base/property.c b/drivers/base/property.c
index f38c21de29b735982480f8042dce35e8d2ed2a8a..43a36d68c3fded1602c9e8ce97358264c9f33c8a 100644 (file)
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -887,6 +887,34 @@ 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 788c6c35291a42c448296876ab6c32bff25a5200..c1a524de67c5b8ab8f1c63ea77365dec085fcd91 100644 (file)
--- 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) ?
+               (!strcmp(to_acpi_data_node(fwnode)->name, name)) : false;
+}
+
 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 288fac5294f5e26aacfe97ac772d5f0247aa1dd2..03039c472e951a718075931f9b24916610aed7e7 100644 (file)
--- 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/of.h b/include/linux/of.h
index c7292e8ea080118b9d09542a875b95ebbddc31b3..8455741e313e75cff84b658d9896c54bf23f3571 100644 (file)
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -238,13 +238,6 @@ static inline unsigned long of_read_ulong(const __be32 *cell, int size)
 #define OF_ROOT_NODE_SIZE_CELLS_DEFAULT 1
 #endif
 
-/* Default string compare functions, Allow arch asm/prom.h to override */
-#if !defined(of_compat_cmp)
-#define of_compat_cmp(s1, s2, l)       strcasecmp((s1), (s2))
-#define of_prop_cmp(s1, s2)            strcmp((s1), (s2))
-#define of_node_cmp(s1, s2)            strcasecmp((s1), (s2))
-#endif
-
 #define OF_IS_DYNAMIC(x) test_bit(OF_DYNAMIC, &x->_flags)
 #define OF_MARK_DYNAMIC(x) set_bit(OF_DYNAMIC, &x->_flags)
 
@@ -726,6 +719,13 @@ static inline void of_property_clear_flag(struct property *p, unsigned long flag
 #define of_match_node(_matches, _node) NULL
 #endif /* CONFIG_OF */
 
+/* Default string compare functions, Allow arch asm/prom.h to override */
+#if !defined(of_compat_cmp)
+#define of_compat_cmp(s1, s2, l)       strcasecmp((s1), (s2))
+#define of_prop_cmp(s1, s2)            strcmp((s1), (s2))
+#define of_node_cmp(s1, s2)            strcasecmp((s1), (s2))
+#endif
+
 #if defined(CONFIG_OF) && defined(CONFIG_NUMA)
 extern int of_node_to_nid(struct device_node *np);
 #else

diff --git a/include/linux/property.h b/include/linux/property.h
index ecab11e407942fcfea3b92d10dc938dd365460cd..3a2f9ae25c86c43827cdcd0c4602cd5e281a4cf9 100644 (file)
--- 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);