dm: usb: Add a new USB controller operation 'get_max_xfer_size'

The HCD may have limitation on the maximum bytes to be transferred
in a USB transfer. USB class driver needs to be aware of this.

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

drivers/usb/host/usb-uclass.c

@@ -150,6 +150,17 @@ int usb_update_hub_device(struct usb_device *udev)
 	return ops->update_hub_device(bus, udev);
 }
 
+int usb_get_max_xfer_size(struct usb_device *udev, size_t *size)
+{
+	struct udevice *bus = udev->controller_dev;
+	struct dm_usb_ops *ops = usb_get_ops(bus);
+
+	if (!ops->get_max_xfer_size)
+		return -ENOSYS;
+
+	return ops->get_max_xfer_size(bus, size);
+}
+
 int usb_stop(void)
 {
 	struct udevice *bus;

include/usb.h

@@ -766,6 +766,14 @@ struct dm_usb_ops {
 	 * representation of this hub can be updated (xHCI)
 	 */
 	int (*update_hub_device)(struct udevice *bus, struct usb_device *udev);
+
+	/**
+	 * get_max_xfer_size() - Get HCD's maximum transfer bytes
+	 *
+	 * The HCD may have limitation on the maximum bytes to be transferred
+	 * in a USB transfer. USB class driver needs to be aware of this.
+	 */
+	int (*get_max_xfer_size)(struct udevice *bus, size_t *size);
 };
 
 #define usb_get_ops(dev)	((struct dm_usb_ops *)(dev)->driver->ops)
@@ -939,7 +947,7 @@ int usb_new_device(struct usb_device *dev);
 int usb_alloc_device(struct usb_device *dev);
 
 /**
- * update_hub_device() - Update HCD's internal representation of hub
+ * usb_update_hub_device() - Update HCD's internal representation of hub
  *
  * After a hub descriptor is fetched, notify HCD so that its internal
  * representation of this hub can be updated.
@@ -950,6 +958,18 @@ int usb_alloc_device(struct usb_device *dev);
 int usb_update_hub_device(struct usb_device *dev);
 
 /**
+ * usb_get_max_xfer_size() - Get HCD's maximum transfer bytes
+ *
+ * The HCD may have limitation on the maximum bytes to be transferred
+ * in a USB transfer. USB class driver needs to be aware of this.
+ *
+ * @dev:		USB device
+ * @size:		maximum transfer bytes
+ * @return 0 if OK, -ve on error
+ */
+int usb_get_max_xfer_size(struct usb_device *dev, size_t *size);
+
+/**
  * usb_emul_setup_device() - Set up a new USB device emulation
  *
  * This is normally called when a new emulation device is bound. It tells