[PATCH v5 3/3] usb: udc: add usb_udc_activation_handler

[Peter Chen <peter.chen@xxxxxxxxxxxxx>]

Currently, connect gadget is unconditional after binding,
but some function drivers may want to connect gadget on the fly.
With this API, the function driver can disconnect gadget during
the initialization, and connect gadget when it wants.

During this API, the deactivation count will be update, and it
will try to connect or disconnect gadget. It can be used to
enable functions for gadget when necessary.

Signed-off-by: Peter Chen <peter.chen@xxxxxxxxxxxxx>
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
---
 drivers/usb/gadget/udc/udc-core.c | 35 ++++++++++++++++++++++++++++++++++-
 include/linux/usb/gadget.h        |  5 +++++
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/udc/udc-core.c b/drivers/usb/gadget/udc/udc-core.c
index 9396a86..a757334 100644
--- a/drivers/usb/gadget/udc/udc-core.c
+++ b/drivers/usb/gadget/udc/udc-core.c
@@ -37,6 +37,7 @@
  * @list - for use by the udc class driver
  * @vbus - for udcs who care about vbus status, this value is real vbus status;
  * for udcs who do not care about vbus status, this value is always true
+ * @deactivations - the deactivation count to connect or disconnect gadget
  *
  * This represents the internal data structure which is used by the UDC-class
  * to hold information about udc driver and gadget together.
@@ -47,6 +48,7 @@ struct usb_udc {
 	struct device			dev;
 	struct list_head		list;
 	bool				vbus;
+	int				deactivations;
 };
 
 static struct class *udc_class;
@@ -168,13 +170,44 @@ EXPORT_SYMBOL_GPL(usb_gadget_set_state);
 
 static void usb_udc_connect_control(struct usb_udc *udc)
 {
-	if (udc->vbus)
+	if (udc->vbus && !udc->deactivations)
 		usb_gadget_connect(udc->gadget);
 	else
 		usb_gadget_disconnect(udc->gadget);
 }
 
 /**
+ * usb_udc_activation_handler - updates udc's deactivation count and
+ * try to connect or disconnect
+ *
+ * @gadget: The gadget which the function is at
+ * @active: the function needs to be active or not
+ *
+ * The composite core or function driver calls it when it
+ * wants to activate or deactivate function.
+ */
+void usb_udc_activation_handler(struct usb_gadget *gadget, bool active)
+{
+	struct usb_udc *udc = usb_gadget_find_udc(gadget);
+
+	mutex_lock(&udc_lock);
+	if (udc) {
+		if (active) {
+			if (udc->deactivations == 0) {
+				WARN_ON(1);
+				return;
+			}
+			udc->deactivations--;
+		} else {
+			udc->deactivations++;
+		}
+		usb_udc_connect_control(udc);
+	}
+	mutex_unlock(&udc_lock);
+}
+EXPORT_SYMBOL_GPL(usb_udc_activation_handler);
+
+/**
  * usb_udc_vbus_handler - updates the udc core vbus status, and try to
  * connect or disconnect gadget
  * @gadget: The gadget which vbus change occurs
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 2be007a..4d1adea 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -1034,6 +1034,11 @@ extern void usb_udc_vbus_handler(struct usb_gadget *gadget, bool status);
 
 /*-------------------------------------------------------------------------*/
 
+/* utility to activate or deactive function */
+extern void usb_udc_activation_handler(struct usb_gadget *gadget, bool active);
+
+/*-------------------------------------------------------------------------*/
+
 /* utility wrapping a simple endpoint selection policy */
 
 extern struct usb_ep *usb_ep_autoconfig(struct usb_gadget *,
-- 
1.9.1

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