via.c

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		printk(KERN_DEBUG "VIA2:  IFR = 0x%02X  IER = 0x%02X\n",
			(uint) via2[rIFR], (uint) via2[rIER]);
		printk(KERN_DEBUG "      SIFR = 0x%02X SIER = 0x%02X\n",
			(uint) via2[rSIFR], (uint) via2[rSIER]);
	} else {
		printk(KERN_DEBUG "VIA2: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
			(uint) via2[vDirA], (uint) via2[vDirB],
			(uint) via2[vACR]);
		printk(KERN_DEBUG "         PCR = 0x%02X  IFR = 0x%02X IER = 0x%02X\n",
			(uint) via2[vPCR],
			(uint) via2[vIFR], (uint) via2[vIER]);
	}
}

/*
 * This is always executed with interrupts disabled.
 *
 * TBI: get time offset between scheduling timer ticks
 */

unsigned long mac_gettimeoffset (void)
{
	unsigned long ticks, offset = 0;

	/* read VIA1 timer 2 current value */
	ticks = via1[vT1CL] | (via1[vT1CH] << 8);
	/* The probability of underflow is less than 2% */
	if (ticks > MAC_CLOCK_TICK - MAC_CLOCK_TICK / 50)
		/* Check for pending timer interrupt in VIA1 IFR */
		if (via1[vIFR] & 0x40) offset = TICK_SIZE;

	ticks = MAC_CLOCK_TICK - ticks;
	ticks = ticks * 10000L / MAC_CLOCK_TICK;

	return ticks + offset;
}

/*
 * Flush the L2 cache on Macs that have it by flipping
 * the system into 24-bit mode for an instant.
 */

void via_flush_cache(void)
{
	via2[gBufB] &= ~VIA2B_vMode32;
	via2[gBufB] |= VIA2B_vMode32;
}

/*
 * Return the status of the L2 cache on a IIci
 */

int via_get_cache_disable(void)
{
	/* Safeguard against being called accidentally */
	if (!via2) {
		printk(KERN_ERR "via_get_cache_disable called on a non-VIA machine!\n");
		return 1;
	}

	return (int) via2[gBufB] & VIA2B_vCDis;
}

/*
 * Initialize VIA2 for Nubus access
 */

void __init via_nubus_init(void)
{
	/* unlock nubus transactions */

	if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
	    (macintosh_config->adb_type != MAC_ADB_PB2)) {
		/* set the line to be an output on non-RBV machines */
		if (!rbv_present)
			via2[vDirB] |= 0x02;

		/* this seems to be an ADB bit on PMU machines */
		/* according to MkLinux.  -- jmt               */
		via2[gBufB] |= 0x02;
	}

	/* Disable all the slot interrupts (where possible). */

	switch (macintosh_config->via_type) {
	case MAC_VIA_II:
		/* Just make the port A lines inputs. */
		switch(macintosh_config->ident) {
		case MAC_MODEL_II:
		case MAC_MODEL_IIX:
		case MAC_MODEL_IICX:
		case MAC_MODEL_SE30:
			/* The top two bits are RAM size outputs. */
			via2[vDirA] &= 0xC0;
			break;
		default:
			via2[vDirA] &= 0x80;
		}
		break;
	case MAC_VIA_IIci:
		/* RBV. Disable all the slot interrupts. SIER works like IER. */
		via2[rSIER] = 0x7F;
		break;
	case MAC_VIA_QUADRA:
		/* Disable the inactive slot interrupts by making those lines outputs. */
		if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
		    (macintosh_config->adb_type != MAC_ADB_PB2)) {
			via2[vBufA] |= 0x7F;
			via2[vDirA] |= 0x7F;
		}
		break;
	}
}

/*
 * The generic VIA interrupt routines (shamelessly stolen from Alan Cox's
 * via6522.c :-), disable/pending masks added.
 */

irqreturn_t via1_irq(int irq, void *dev_id)
{
	int irq_num;
	unsigned char irq_bit, events;

	events = via1[vIFR] & via1[vIER] & 0x7F;
	if (!events)
		return IRQ_NONE;

	irq_num = VIA1_SOURCE_BASE;
	irq_bit = 1;
	do {
		if (events & irq_bit) {
			via1[vIFR] = irq_bit;
			m68k_handle_int(irq_num);
		}
		++irq_num;
		irq_bit <<= 1;
	} while (events >= irq_bit);

#if 0 /* freakin' pmu is doing weird stuff */
	if (!oss_present) {
		/* This (still) seems to be necessary to get IDE
		   working.  However, if you enable VBL interrupts,
		   you're screwed... */
		/* FIXME: should we check the SLOTIRQ bit before
                   pulling this stunt? */
		/* No, it won't be set. that's why we're doing this. */
		via_irq_disable(IRQ_MAC_NUBUS);
		via_irq_clear(IRQ_MAC_NUBUS);
		m68k_handle_int(IRQ_MAC_NUBUS);
		via_irq_enable(IRQ_MAC_NUBUS);
	}
#endif
	return IRQ_HANDLED;
}

irqreturn_t via2_irq(int irq, void *dev_id)
{
	int irq_num;
	unsigned char irq_bit, events;

	events = via2[gIFR] & via2[gIER] & 0x7F;
	if (!events)
		return IRQ_NONE;

	irq_num = VIA2_SOURCE_BASE;
	irq_bit = 1;
	do {
		if (events & irq_bit) {
			via2[gIFR] = irq_bit | rbv_clear;
			m68k_handle_int(irq_num);
		}
		++irq_num;
		irq_bit <<= 1;
	} while (events >= irq_bit);
	return IRQ_HANDLED;
}

/*
 * Dispatch Nubus interrupts. We are called as a secondary dispatch by the
 * VIA2 dispatcher as a fast interrupt handler.
 */

irqreturn_t via_nubus_irq(int irq, void *dev_id)
{
	int slot_irq;
	unsigned char slot_bit, events;

	events = ~via2[gBufA] & 0x7F;
	if (rbv_present)
		events &= via2[rSIER];
	else
		events &= ~via2[vDirA];
	if (!events)
		return IRQ_NONE;

	do {
		slot_irq = IRQ_NUBUS_F;
		slot_bit = 0x40;
		do {
			if (events & slot_bit) {
				events &= ~slot_bit;
				m68k_handle_int(slot_irq);
			}
			--slot_irq;
			slot_bit >>= 1;
		} while (events);

 		/* clear the CA1 interrupt and make certain there's no more. */
		via2[gIFR] = 0x02 | rbv_clear;
		events = ~via2[gBufA] & 0x7F;
		if (rbv_present)
			events &= via2[rSIER];
		else
			events &= ~via2[vDirA];
	} while (events);
	return IRQ_HANDLED;
}

void via_irq_enable(int irq) {
	int irq_src	= IRQ_SRC(irq);
	int irq_idx	= IRQ_IDX(irq);

#ifdef DEBUG_IRQUSE
	printk(KERN_DEBUG "via_irq_enable(%d)\n", irq);
#endif

	if (irq_src == 1) {
		via1[vIER] = IER_SET_BIT(irq_idx);
	} else if (irq_src == 2) {
		if (irq != IRQ_MAC_NUBUS || nubus_disabled == 0)
			via2[gIER] = IER_SET_BIT(irq_idx);
	} else if (irq_src == 7) {
		switch (macintosh_config->via_type) {
		case MAC_VIA_II:
			nubus_disabled &= ~(1 << irq_idx);
			/* Enable the CA1 interrupt when no slot is disabled. */
			if (!nubus_disabled)
				via2[gIER] = IER_SET_BIT(1);
			break;
		case MAC_VIA_IIci:
			/* On RBV, enable the slot interrupt.
			 * SIER works like IER.
			 */
			via2[rSIER] = IER_SET_BIT(irq_idx);
			break;
		case MAC_VIA_QUADRA:
			/* Make the port A line an input to enable the slot irq.
			 * But not on PowerBooks, that's ADB.
			 */
			if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
			    (macintosh_config->adb_type != MAC_ADB_PB2))
				via2[vDirA] &= ~(1 << irq_idx);
			break;
		}
	}
}

void via_irq_disable(int irq) {
	int irq_src	= IRQ_SRC(irq);
	int irq_idx	= IRQ_IDX(irq);

#ifdef DEBUG_IRQUSE
	printk(KERN_DEBUG "via_irq_disable(%d)\n", irq);
#endif

	if (irq_src == 1) {
		via1[vIER] = IER_CLR_BIT(irq_idx);
	} else if (irq_src == 2) {
		via2[gIER] = IER_CLR_BIT(irq_idx);
	} else if (irq_src == 7) {
		switch (macintosh_config->via_type) {
		case MAC_VIA_II:
			nubus_disabled |= 1 << irq_idx;
			if (nubus_disabled)
				via2[gIER] = IER_CLR_BIT(1);
			break;
		case MAC_VIA_IIci:
			via2[rSIER] = IER_CLR_BIT(irq_idx);
			break;
		case MAC_VIA_QUADRA:
			if ((macintosh_config->adb_type != MAC_ADB_PB1) &&
			    (macintosh_config->adb_type != MAC_ADB_PB2))
				via2[vDirA] |= 1 << irq_idx;
			break;
		}
	}
}

void via_irq_clear(int irq) {
	int irq_src	= IRQ_SRC(irq);
	int irq_idx	= IRQ_IDX(irq);
	int irq_bit	= 1 << irq_idx;

	if (irq_src == 1) {
		via1[vIFR] = irq_bit;
	} else if (irq_src == 2) {
		via2[gIFR] = irq_bit | rbv_clear;
	} else if (irq_src == 7) {
		/* FIXME: There is no way to clear an individual nubus slot
		 * IRQ flag, other than getting the device to do it.
		 */
	}
}

/*
 * Returns nonzero if an interrupt is pending on the given
 * VIA/IRQ combination.
 */

int via_irq_pending(int irq)
{
	int irq_src	= IRQ_SRC(irq);
	int irq_idx	= IRQ_IDX(irq);
	int irq_bit	= 1 << irq_idx;

	if (irq_src == 1) {
		return via1[vIFR] & irq_bit;
	} else if (irq_src == 2) {
		return via2[gIFR] & irq_bit;
	} else if (irq_src == 7) {
		/* Always 0 for MAC_VIA_QUADRA if the slot irq is disabled. */
		return ~via2[gBufA] & irq_bit;
	}
	return 0;
}