TUSB_EP_RX_OFFSET
musb_writel(ep_conf, TUSB_EP_RX_OFFSET,
remaining = musb_readl(ep_conf, TUSB_EP_RX_OFFSET);
dma_remaining = musb_readl(ep_conf, TUSB_EP_RX_OFFSET);
musb_writel(ep_conf, TUSB_EP_RX_OFFSET,