usb: gadget: Introduce handle_interrupts ops to USB_GADGET_GENERIC uclass

Introduce .ops for USB_GADGET_GENERIC uclass. The first new ops is
.handle_interrupts which must be implemented by DM capable USB gadget
controller drivers and must implement interrupt handling similar to
dm_usb_gadget_handle_interrupts(). This patch currently provides weak
dm_usb_gadget_handle_interrupts() implementation which is overridden by
the drivers, but this will be removed once conversion to handle_interrupts
callback is complete.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Tested-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Tested-by: Mattijs Korpershoek <mkorpershoek@baylibre.com> # vim3
Link: https://lore.kernel.org/r/20240614005309.34433-2-marek.vasut+renesas@mailbox.org
[mkorpershoek: fixed trivial typo in commit message]
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
diff --git a/drivers/usb/gadget/udc/udc-uclass.c b/drivers/usb/gadget/udc/udc-uclass.c
index 5dc23a5..2320039 100644
--- a/drivers/usb/gadget/udc/udc-uclass.c
+++ b/drivers/usb/gadget/udc/udc-uclass.c
@@ -12,6 +12,25 @@
 #include <linux/usb/gadget.h>
 
 #if CONFIG_IS_ENABLED(DM_USB_GADGET)
+static inline const struct usb_gadget_generic_ops *
+usb_gadget_generic_dev_ops(struct udevice *dev)
+{
+	return (const struct usb_gadget_generic_ops *)dev->driver->ops;
+}
+
+__weak int dm_usb_gadget_handle_interrupts(struct udevice *dev)
+{
+	const struct usb_gadget_generic_ops *ops;
+
+	ops = usb_gadget_generic_dev_ops(dev);
+	if (!ops)
+		return -EFAULT;
+	if (!ops->handle_interrupts)
+		return -ENOSYS;
+
+	return ops->handle_interrupts(dev);
+}
+
 int udc_device_get_by_index(int index, struct udevice **udev)
 {
 	struct udevice *dev = NULL;
@@ -54,6 +73,11 @@
 {
 	return board_usb_cleanup(legacy_index, USB_INIT_DEVICE);
 }
+
+__weak int dm_usb_gadget_handle_interrupts(struct udevice *dev)
+{
+	return 0;
+}
 #endif
 
 #if CONFIG_IS_ENABLED(DM)
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 36572be..cf21616 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -971,6 +971,14 @@
 extern int dm_usb_gadget_handle_interrupts(struct udevice *);
 
 /**
+ * struct usb_gadget_generic_ops - The functions that a gadget driver must implement.
+ * @handle_interrupts: Handle UDC interrupts.
+ */
+struct usb_gadget_generic_ops {
+	int (*handle_interrupts)(struct udevice *udevice);
+};
+
+/**
  * udc_device_get_by_index() - Get UDC udevice by index
  * @index: UDC device index
  * @udev: UDC udevice matching the index (if found)