[PATCH 3/5] usb: roles: add API to get usb_role_switch by node

Chunfeng Yun
2019-03-08T06:13:40Z

Add usb_role_switch_get_by_node() to make easier to get
usb_role_switch by node which register it.
It's useful when there is not device_connection registered
between two drivers and only knows the node which register
usb_role_switch.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
---
drivers/usb/roles/class.c | 30 ++++++++++++++++++++++++++++++
include/linux/usb/role.h | 1 +
2 files changed, 31 insertions(+)

diff --git a/drivers/usb/roles/class.c b/drivers/usb/roles/class.c
index 99116af07f1d..284b19856dc4 100644
--- a/drivers/usb/roles/class.c
+++ b/drivers/usb/roles/class.c
@@ -11,6 +11,7 @@
#include <linux/device.h>
#include <linux/module.h>
#include <linux/mutex.h>
+#include <linux/of.h>
#include <linux/slab.h>

static struct class *role_class;
@@ -121,6 +122,35 @@ struct usb_role_switch *usb_role_switch_get(struct device *dev)
}
EXPORT_SYMBOL_GPL(usb_role_switch_get);

+static int __switch_match_node(struct device *dev, const void *node)
+{
+ return dev->parent->of_node == (const struct device_node *)node;
+}
+
+/**
+ * usb_role_switch_get_by_node - Find USB role switch by it's parent node
+ * @node: The node that register USB role switch
+ *
+ * Finds and returns role switch registered by @node. The reference count
+ * for the found switch is incremented.
+ */
+struct usb_role_switch *usb_role_switch_get_by_node(struct device_node *node)
+{
+ struct usb_role_switch *sw;
+ struct device *dev;
+
+ dev = class_find_device(role_class, NULL, node,
+ __switch_match_node);
+ if (!dev)
+ return ERR_PTR(-EPROBE_DEFER);
+
+ sw = to_role_switch(dev);
+ WARN_ON(!try_module_get(sw->dev.parent->driver->owner));
+
+ return sw;
+}
+EXPORT_SYMBOL_GPL(usb_role_switch_get_by_node);
+
/**
* usb_role_switch_put - Release handle to a switch
* @sw: USB Role Switch
diff --git a/include/linux/usb/role.h b/include/linux/usb/role.h
index edc51be4a77c..056498b83dee 100644
--- a/include/linux/usb/role.h
+++ b/include/linux/usb/role.h
@@ -42,6 +42,7 @@ struct usb_role_switch_desc {

int usb_role_switch_set_role(struct usb_role_switch *sw, enum usb_role role);
enum usb_role usb_role_switch_get_role(struct usb_role_switch *sw);
+struct usb_role_switch *usb_role_switch_get_by_node(struct device_node *node);
struct usb_role_switch *usb_role_switch_get(struct device *dev);
void usb_role_switch_put(struct usb_role_switch *sw);

--
2.20.1