usb: emul: Expose find_descriptor() as a public API

This can be useful outside of the sandbox usb emulation uclass
driver. Expose it as a public API with a proper prefix (usb_emul_).

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

drivers/usb/emul/usb-emul-uclass.c

@@ -52,7 +52,7 @@ static int usb_emul_get_string(struct usb_string *strings, int index,
 	return -EINVAL;
 }
 
-static struct usb_generic_descriptor **find_descriptor(
+struct usb_generic_descriptor **usb_emul_find_descriptor(
 		struct usb_generic_descriptor **ptr, int type, int index)
 {
 	debug("%s: type=%x, index=%d\n", __func__, type, index);
@@ -91,8 +91,7 @@ static int usb_emul_get_descriptor(struct usb_dev_platdata *plat, int value,
 					   length);
 	}
 
-	ptr = find_descriptor((struct usb_generic_descriptor **)plat->desc_list,
-			      type, index);
+	ptr = usb_emul_find_descriptor(plat->desc_list, type, index);
 	if (!ptr) {
 		debug("%s: Could not find descriptor type %d, index %d\n",
 		      __func__, type, index);

include/usb.h

@@ -1056,6 +1056,17 @@ int usb_emul_find(struct udevice *bus, ulong pipe, int port1,
 int usb_emul_find_for_dev(struct udevice *dev, struct udevice **emulp);
 
 /**
+ * usb_emul_find_descriptor() - Find a USB descriptor of a particular device
+ *
+ * @ptr:	a pointer to a list of USB descriptor pointers
+ * @type:	type of USB descriptor to find
+ * @index:	if @type is USB_DT_CONFIG, this is the configuration value
+ * @return a pointer to the USB descriptor found, NULL if not found
+ */
+struct usb_generic_descriptor **usb_emul_find_descriptor(
+		struct usb_generic_descriptor **ptr, int type, int index);
+
+/**
  * usb_emul_reset() - Reset all emulators ready for use
  *
  * Clear out any address information in the emulators and make then ready for