IO_INTR_ACK
intr = readl(timer->interrupt_regs + IO_INTR_ACK);
writel(TIMER_INTR_MSK, timer->interrupt_regs + IO_INTR_ACK);
writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);
writel(TIMER_INTR_ALL, timer->interrupt_regs + IO_INTR_ACK);