[PATCH net-next v4 05/10] drivers: base: Add device_find_in_class_name()

From: Florian Fainelli
Date: Tue Jan 17 2017 - 18:29:03 EST


Add a helper function to lookup a device reference given a class name.
This is a preliminary patch to remove adhoc code from net/dsa/dsa.c and
make it more generic.

Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
---
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 8c25e68e67d7..fb9fced38634 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -2058,6 +2058,37 @@ struct device *device_find_child(struct device *parent, void *data,
}
EXPORT_SYMBOL_GPL(device_find_child);

+static int device_class_name_match(struct device *dev, void *class)
+{
+ if (dev->class != NULL && !strcmp(dev->class->name, class))
+ return 1;
+
+ return 0;
+}
+
+/**
+ * device_find_in_class_name - device iterator for locating a particular device
+ * within the specified class name
+ * @parent: parent struct device
+ * @class_name: Class name to match against
+ *
+ * This function returns 1 if the device (specified by @parent), or one of its child
+ * is in the class whose name is specified by @class_name. Returns 0 otherwise.
+ *
+ * NOTE: you will need to drop the reference with put_device() after use.
+ */
+struct device *device_find_in_class_name(struct device *parent,
+ char *class_name)
+{
+ if (device_class_name_match(parent, class_name)) {
+ get_device(parent);
+ return parent;
+ }
+
+ return device_find_child(parent, class_name, device_class_name_match);
+}
+EXPORT_SYMBOL_GPL(device_find_in_class_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 491b4c0ca633..fbc2a255f92e 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -1120,6 +1120,8 @@ 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_in_class_name(struct device *parent,
+ char *class_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);
--
2.9.3