AST_VHUB_ISR
istat = readl(vhub->regs + AST_VHUB_ISR);
writel(istat, vhub->regs + AST_VHUB_ISR);
writel(VHUB_IRQ_ACK_ALL, vhub->regs + AST_VHUB_ISR);
writel(VHUB_IRQ_ACK_ALL, vhub->regs + AST_VHUB_ISR);