[PATCH v3 05/13] driver core: Add helper device_find_child_by_name()

Heikki Krogerus
2019-04-12T13:41:44Z

It looks like the child device is often matched with a name.
This introduces a helper that does it automatically.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
---
drivers/base/core.c | 31 +++++++++++++++++++++++++++++++
include/linux/device.h | 2 ++
2 files changed, 33 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 4aeaa0c92bda..5819ba4c9d4c 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -2469,6 +2469,37 @@ struct device *device_find_child(struct device *parent, void *data,
}
EXPORT_SYMBOL_GPL(device_find_child);

+/**
+ * device_find_child_by_name - device iterator for locating a child device.
+ * @parent: parent struct device
+ * @name: name of the child device
+ *
+ * This is similar to the device_find_child() function above, but it
+ * returns a reference to a device that has the name @name.
+ *
+ * The callback should return NULL if the child is not found and a reference to
+ * the child device if it is found.
+ *
+ * NOTE: you will need to drop the reference with put_device() after use.
+ */
+struct device *device_find_child_by_name(struct device *parent,
+ const char *name)
+{
+ struct klist_iter i;
+ struct device *child;
+
+ if (!parent)
+ return NULL;
+
+ klist_iter_init(&parent->p->klist_children, &i);
+ while ((child = next_device(&i)))
+ if (!strcmp(dev_name(child), name) && get_device(child))
+ break;
+ klist_iter_exit(&i);
+ return child;
+}
+EXPORT_SYMBOL_GPL(device_find_child_by_name);
+
int __init devices_init(void)
{
devices_kset = kset_create_and_add("devices", &device_uevent_ops, NULL);
diff --git a/include/linux/device.h b/include/linux/device.h
index 4457e560bc2b..fadb84dd07f9 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -1250,6 +1250,8 @@ extern int device_for_each_child_reverse(struct device *dev, void *data,
int (*fn)(struct device *dev, void *data));
extern struct device *device_find_child(struct device *dev, void *data,
int (*match)(struct device *dev, void *data));
+extern struct device *device_find_child_by_name(struct device *parent,
+ const char *name);
extern int device_rename(struct device *dev, const char *new_name);
extern int device_move(struct device *dev, struct device *new_parent,
enum dpm_order dpm_order);
--
2.20.1