[PATCH v4 16/43] usb: gadget: composite: add usb_function_get_ep() function

[Robert Baldyga]

Introduce function returning endpoint of given index in active altsetting
of specified interface. It's intended to be used in set_alt() callback
to obtain endpoints of currently selected altsetting.

Signed-off-by: Robert Baldyga <r.baldyga@xxxxxxxxxxx>
---
 drivers/usb/gadget/composite.c | 33 +++++++++++++++++++++++++++++++++
 include/linux/usb/composite.h  |  2 ++
 2 files changed, 35 insertions(+)

diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index a4b5346..452294e 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -670,6 +670,39 @@ static int usb_interface_id_to_index(struct usb_function *f, u8 id)
 }
 
 /**
+ * usb_function_get_ep - obtains endpoint of given index from active
+ *	altsetting of given interface
+ * @f: USB function
+ * @i: index of interface in given function
+ * @e: index of endpoint in active altsetting of given interface
+ *
+ * This function is designed to be used in set_alt() callback, when
+ * new altsetting is selected. It allows to obtain endpoints assigned
+ * to altsetting during autoconfig process.
+ *
+ * Returns pointer to endpoint on success or NULL on failure.
+ */
+struct usb_ep *usb_function_get_ep(struct usb_function *f, int i, int e)
+{
+	struct usb_composite_altset *altset;
+	int selected_altset;
+
+	if (!f->descs)
+		return NULL;
+	if (i >= f->descs->intfs_num)
+		return NULL;
+
+	selected_altset = f->descs->intfs[i]->cur_altset;
+	altset = f->descs->intfs[i]->altsets[selected_altset];
+
+	if (e >= altset->eps_num)
+		return NULL;
+
+	return altset->eps[e]->ep;
+}
+EXPORT_SYMBOL_GPL(usb_function_get_ep);
+
+/**
  * usb_interface_id() - allocate an unused interface ID
  * @config: configuration associated with the interface
  * @function: function handling the interface
diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h
index aa55377..2e646e3 100644
--- a/include/linux/usb/composite.h
+++ b/include/linux/usb/composite.h
@@ -425,6 +425,8 @@ int usb_ep_add_vendor_desc(struct usb_function *f, int i, int a, int e,
 		const struct usb_descriptor_header *desc);
 
 
+struct usb_ep *usb_function_get_ep(struct usb_function *f, int intf, int ep);
+
 int usb_interface_id(struct usb_configuration *, struct usb_function *);
 
 int config_ep_by_speed(struct usb_gadget *g, struct usb_function *f,
-- 
1.9.1