irq_unmask		= titan_enable_irq,
       .irq_mask		= titan_disable_irq,
       .irq_mask_ack		= titan_disable_irq,
       .irq_set_affinity	= titan_set_irq_affinity,
};

static irqreturn_t
titan_intr_nop(int irq, void *dev_id)
{
      /*
       * This is a NOP interrupt handler for the purposes of
       * event counting -- just return.
       */                                                                     
       return IRQ_HANDLED;
}

static void __init
titan_init_irq(void)
{
	if (alpha_using_srm && !alpha_mv.device_interrupt)
		alpha_mv.device_interrupt = titan_srm_device_interrupt;
	if (!alpha_mv.device_interrupt)
		alpha_mv.device_interrupt = titan_device_interrupt;

	titan_update_irq_hw(0);

	init_titan_irqs(&titan_irq_type, 16, 63 + 16);
}
  
static void __init
titan_legacy_init_irq(void)
{
	/* init the legacy dma controller */
	outb(0, DMA1_RESET_REG);
	outb(0, DMA2_RESET_REG);
	outb(DMA_MODE_CASCADE, DMA2_MODE_REG);
	outb(0, DMA2_MASK_REG);

	/* init the legacy irq controller */
	init_i8259a_irqs();

	/* init the titan irqs */
	titan_init_irq();
}

void
titan_dispatch_irqs(u64 mask)
{
	unsigned long vector;

	/*
	 * Mask down to those interrupts which are enable on this processor
	 */
	mask &= titan_cpu_irq_affinity[smp_processor_id()];

	/*
	 * Dispatch all requested interrupts 
	 */
	while (mask) {
		/* convert to SRM vector... priority is <63> -> <0> */
		vector = 63 - __kernel_ctlz(mask);
		mask &= ~(1UL << vector);	/* clear it out 	 */
		vector = 0x900 + (vector << 4);	/* convert to SRM vector */
		
		/* dispatch it */
		alpha_mv.device_interrupt(vector);
	}
}