[PATCH 30/36] driver core: Introduce device_find_child().

From: Cornelia Huck <cornelia.huck@xxxxxxxxxx>

Introduce device_find_child() to match device_for_each_child().

Signed-off-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
drivers/base/core.c | 33 +++++++++++++++++++++++++++++++++
include/linux/device.h | 2 ++
2 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 5d11bbd..a29e685 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -750,12 +750,45 @@ int device_for_each_child(struct device
return error;
}

+/**
+ * device_find_child - device iterator for locating a particular device.
+ * @parent: parent struct device
+ * @data: Data to pass to match function
+ * @match: Callback function to check device
+ *
+ * This is similar to the device_for_each_child() function above, but it
+ * returns a reference to a device that is 'found' for later use, as
+ * determined by the @match callback.
+ *
+ * The callback should return 0 if the device doesn't match and non-zero
+ * if it does. If the callback returns non-zero and a reference to the
+ * current device can be obtained, this function will return to the caller
+ * and not iterate over any more devices.
+ */
+struct device * device_find_child(struct device *parent, void *data,
+ int (*match)(struct device *, void *))
+{
+ struct klist_iter i;
+ struct device *child;
+
+ if (!parent)
+ return NULL;
+
+ klist_iter_init(&parent->klist_children, &i);
+ while ((child = next_device(&i)))
+ if (match(child, data) && get_device(child))
+ break;
+ klist_iter_exit(&i);
+ return child;
+}
+
int __init devices_init(void)
{
return subsystem_register(&devices_subsys);
}

EXPORT_SYMBOL_GPL(device_for_each_child);
+EXPORT_SYMBOL_GPL(device_find_child);

EXPORT_SYMBOL_GPL(device_initialize);
EXPORT_SYMBOL_GPL(device_add);
diff --git a/include/linux/device.h b/include/linux/device.h
index 2d9dc35..0a0370c 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -421,6 +421,8 @@ extern int __must_check device_add(struc
extern void device_del(struct device * dev);
extern int device_for_each_child(struct device *, void *,
int (*fn)(struct device *, void *));
+extern struct device *device_find_child(struct device *, void *data,
+ int (*match)(struct device *, void *));
extern int device_rename(struct device *dev, char *new_name);

/*
--
1.4.4.1

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