/*
 *	6522 Versatile Interface Adapter (VIA)
 *
 *	There are two of these on the Mac II. Some IRQ's are vectored
 *	via them as are assorted bits and bobs - eg RTC, ADB.
 *
 * CSA: Motorola seems to have removed documentation on the 6522 from
 * their web site; try
 *     http://nerini.drf.com/vectrex/other/text/chips/6522/
 *     http://www.zymurgy.net/classic/vic20/vicdet1.htm
 * and
 *     http://193.23.168.87/mikro_laborversuche/via_iobaustein/via6522_1.html
 * for info.  A full-text web search on 6522 AND VIA will probably also
 * net some usefulness. <cananian@alumni.princeton.edu> 20apr1999
 *
 * PRAM/RTC access algorithms are from the NetBSD RTC toolkit version 1.08b
 * by Erik Vogan and adapted to Linux by Joshua M. Thompson (funaho@jurai.org)
 *
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/init.h>

#include <asm/bootinfo.h> 
#include <asm/macintosh.h> 
#include <asm/macints.h>
#include <asm/machw.h> 
#include <asm/mac_via.h>
#include <asm/mac_psc.h>

volatile __u8 *via1, *via2;
#if 0
/* See note in mac_via.h about how this is possibly not useful */
volatile long *via_memory_bogon=(long *)&via_memory_bogon;
#endif
int  rbv_present,via_alt_mapping;
__u8 rbv_clear;

/*
 * Globals for accessing the VIA chip registers without having to
 * check if we're hitting a real VIA or an RBV. Normally you could
 * just hit the combined register (ie, vIER|rIER) but that seems to
 * break on AV Macs...probably because they actually decode more than
 * eight address bits. Why can't Apple engineers at least be
 * _consistantly_ lazy?                          - 1999-05-21 (jmt)
 */

static int gIER,gIFR,gBufA,gBufB;

/*
 * Timer defs.
 */

#define TICK_SIZE		10000
#define MAC_CLOCK_TICK		(783300/HZ)		/* ticks per HZ */
#define MAC_CLOCK_LOW		(MAC_CLOCK_TICK&0xFF)
#define MAC_CLOCK_HIGH		(MAC_CLOCK_TICK>>8)

static int  nubus_active;

void via_debug_dump(void);
void via1_irq(int, void *, struct pt_regs *);
void via2_irq(int, void *, struct pt_regs *);
void via_nubus_irq(int, void *, struct pt_regs *);
void via_irq_enable(int irq);
void via_irq_disable(int irq);
void via_irq_clear(int irq);

extern void mac_bang(int, void *, struct pt_regs *);
extern void mac_SCC_handler(int, void *, struct pt_regs *);
extern int console_loglevel;
extern int oss_present;

/*
 * Initialize the VIAs
 *
 * First we figure out where they actually _are_ as well as what type of
 * VIA we have for VIA2 (it could be a real VIA or an RBV or even an OSS.)
 * Then we pretty much clear them out and disable all IRQ sources.
 *
 * Note: the OSS is actually "detected" here and not in oss_init(). It just
 *	 seems more logical to do it here since via_init() needs to know
 *	 these things anyways.
 */

__initfunc(void via_init(void))
{
	switch(macintosh_config->via_type) {

		/* IIci, IIsi, IIvx, IIvi (P6xx), LC series */

		case MAC_VIA_IIci:	
			via1 = (void *) VIA1_BASE;
			if (macintosh_config->ident == MAC_MODEL_IIFX) {
				via2 = NULL;
				rbv_present = 0;
				oss_present = 1;
			} else {
				via2 = (void *) RBV_BASE;
				rbv_present = 1;
				oss_present = 0;
			}
			if (macintosh_config->ident == MAC_MODEL_LCIII) {
				rbv_clear = 0x00;
			} else {
				/* on most RBVs (& unlike the VIAs), you   */
				/* need to set bit 7 when you write to IFR */
				/* in order for your clear to occur.       */
				rbv_clear = 0x80;
			}
			gIER = rIER;
			gIFR = rIFR;
			gBufA = rSIFR;
			gBufB = rBufB;
			break;

		/* Quadra and early MacIIs agree on the VIA locations */

		case MAC_VIA_QUADRA:
		case MAC_VIA_II:
			via1 = (void *) VIA1_BASE;
			via2 = (void *) VIA2_BASE;
			rbv_present = 0;
			oss_present = 0;
			rbv_clear = 0x00;
			gIER = vIER;
			gIFR = vIFR;
			gBufA = vBufA;
			gBufB = vBufB;
			break;
		default:
			panic("UNKNOWN VIA TYPE");
	}

	printk("VIA1 at %p is a 6522 or clone\n", via1);

	printk("VIA2 at %p is ", via2);
	if (rbv_present) {
		printk("an RBV\n");
	} else if (oss_present) {
		printk("an OSS\n");
	} else {
		printk("a 6522 or clone\n");
	}

#ifdef DEBUG_VIA
	via_debug_dump();
#endif

	/*
	 * Shut down all IRQ sources, reset the timers, and
	 * kill the timer latch on VIA1.
	 */

	via_write(via1, vIER, 0x7F);	 
	via_write(via1, vIFR, 0x7F);	 
	via_write(via1, vT1LL, 0);
	via_write(via1, vT1LH, 0);
	via_write(via1, vT1CL, 0);
	via_write(via1, vT1CH, 0);
	via_write(via1, vT2CL, 0);
	via_write(via1, vT2CH, 0);
	via_write(via1, vACR, via_read(via1, vACR) & 0x3F);

	/* 
	 * SE/30: disable video IRQ
	 * XXX: testing for SE/30 VBL
	 */

	if (macintosh_config->ident == MAC_MODEL_SE30) {
		via_write(via1, vBufB, via_read(via1, vBufB) | 0x40);
		via_write(via1, vDirB, via_read(via1, vDirB) | 0x40);
	} 
	
	/*
	 * Set the RTC bits to a known state: all lines to outputs and
	 * RTC disabled (yes that's 0 to enable and 1 to disable).
	 */

	via_write(via1, vDirB, via_read(via1, vDirB) | (VIA1B_vRTCEnb |
						        VIA1B_vRTCClk |
						        VIA1B_vRTCData));
	via_write(via1, vBufB, via_read(via1, vBufB) | (VIA1B_vRTCEnb |
						        VIA1B_vRTCClk));

	/* Everything below this point is VIA2/RBV only... */

	if (oss_present) return;

#if 1
	/* Some machines support an alternate IRQ mapping that spreads  */
	/* Ethernet and Sound out to their own autolevel IRQs and moves */
	/* VIA1 to level 6. A/UX uses this mapping and we do too.  Note */
	/* that the IIfx emulates this alternate mapping using the OSS. */

	switch(macintosh_config->ident) {
		case MAC_MODEL_C610:
		case MAC_MODEL_Q610:
		case MAC_MODEL_C650:
		case MAC_MODEL_Q650:
		case MAC_MODEL_Q700:
		case MAC_MODEL_Q800:
		case MAC_MODEL_Q900:
		case MAC_MODEL_Q950:
			via_alt_mapping = 1;
			via_write(via1, vDirB, via_read(via1, vDirB) | 0x40);
			via_write(via1, vBufB, via_read(via1, vBufB) & ~0x40);
			break;
		default:
			via_alt_mapping = 0;
			break;
	}
#else
	via_alt_mapping = 0;
#endif

	/*
	 * Now initialize VIA2. For RBV we just kill all interrupts;
	 * for a regular VIA we also reset the timers and stuff.
	 */

	via_write(via2, gIER, 0x7F);	 
	via_write(via2, gIFR, 0x7F | rbv_clear);	 
	if (!rbv_present) {
		via_write(via2, vT1LL, 0);
		via_write(via2, vT1LH, 0);
		via_write(via2, vT1CL, 0);
		via_write(via2, vT1CH, 0);
		via_write(via2, vT2CL, 0);
		via_write(via2, vT2CH, 0);
		via_write(via2, vACR, via_read(via2, vACR) & 0x3F);
	}
}

/*
 * Start the 100 Hz clock
 */

__initfunc(void via_init_clock(void (*func)(int, void *, struct pt_regs *)))
{	
	via_write(via1, vACR, via_read(via1, vACR) | 0x40);
	via_write(via1, vT1LL, MAC_CLOCK_LOW);
	via_write(via1, vT1LH, MAC_CLOCK_HIGH);
	via_write(via1, vT1CL, MAC_CLOCK_LOW);
	via_write(via1, vT1CH, MAC_CLOCK_HIGH);
	
	request_irq(IRQ_MAC_TIMER_1, func, IRQ_FLG_LOCK, "timer", func);
}

/*
 * Register the interrupt dispatchers for VIA or RBV machines only.
 */

__initfunc(void via_register_interrupts(void))
{
	if (via_alt_mapping) {
		sys_request_irq(IRQ_AUTO_1, via1_irq, IRQ_FLG_LOCK|IRQ_FLG_FAST,
				"Software IRQ", (void *) via1);
		sys_request_irq(IRQ_AUTO_6, via1_irq, IRQ_FLG_LOCK|IRQ_FLG_FAST,
				"VIA1 Dispatch", (void *) via1);
	} else {
		sys_request_irq(IRQ_AUTO_1, via1_irq, IRQ_FLG_LOCK|IRQ_FLG_FAST,
				"VIA1 Dispatch", (void *) via1);
#if 0 /* interferes with serial on some machines */
		if (!psc_present) {
			sys_request_irq(IRQ_AUTO_6, mac_bang, IRQ_FLG_LOCK,
					"Off Switch", mac_bang);
		}
#endif
	}
	sys_request_irq(IRQ_AUTO_2, via2_irq, IRQ_FLG_LOCK|IRQ_FLG_FAST,
			"VIA2 Dispatch", (void *) via2);
	if (!psc_present) {
		sys_request_irq(IRQ_AUTO_4, mac_SCC_handler, IRQ_FLG_LOCK,
				"SCC Dispatch", mac_SCC_handler);
	}
	request_irq(IRQ_MAC_NUBUS, via_nubus_irq, IRQ_FLG_LOCK|IRQ_FLG_FAST,
			"Nubus Dispatch", (void *) via2);
}

/*
 * Debugging dump, used in various places to see what's going on.
 */

void via_debug_dump(void)
{
	printk("VIA1: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
		via_read(via1, vDirA),
		via_read(via1, vDirB),
		via_read(via1, vACR));
	printk("         PCR = 0x%02X  IFR = 0x%02X IER = 0x%02X\n",
		via_read(via1, vPCR),
		via_read(via1, vIFR),
		via_read(via1, vIER));
	if (oss_present) {
		printk("VIA2: <OSS>\n");
	} else if (rbv_present) {
		printk("VIA2:  IFR = 0x%02X  IER = 0x%02X\n",
			via_read(via2, rIFR),
			via_read(via2, rIER));
		printk("      SIFR = 0x%02X SIER = 0x%02X\n",
			via_read(via2, rSIFR),
			via_read(via2, rSIER));
	} else {
		printk("VIA2: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
			via_read(via2, vDirA),
			via_read(via2, vDirB),
			via_read(via2, vACR));
		printk("         PCR = 0x%02X  IFR = 0x%02X IER = 0x%02X\n",
			via_read(via2, vPCR),
			via_read(via2, vIFR),
			via_read(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 = via_read(via1, vT1CL) + (via_read(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 (via_read(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)
{
	via_write(via2, gBufB, via_read(via2, vBufB) & ~VIA2B_vMode32);
	via_write(via2, gBufB, via_read(via2, vBufB) | 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 via_read(via2, gBufB) & VIA2B_vCDis;
}

/*
 * VIA-based power switch, for machines that support it.
 */

void via_poweroff(void)
{
	if (rbv_present) {
		via_write(via2, rBufB, via_read(via2, rBufB) & ~0x04);
	} else {
		/* Direction of vDirB is output */
		via_write(via2, vDirB, via_read(via2, vDirB) | 0x04);
		/* Send a value of 0 on that line */
		via_write(via2, vBufB, via_read(via2, vBufB) & ~0x04);
		/* Otherwise it prints "It is now.." then shuts off */
		mdelay(1000);
	}

	/* We should never make it this far... */
	printk ("It is now safe to switch off your machine.\n");
	while(1);
}

/*
 * Initialize VIA2 for Nubus access
 */

__initfunc(void via_nubus_init(void))
{
	nubus_active = 0;

	/* unlock nubus transactions */

	if (!rbv_present) {
		/* set the line to be an output on non-RBV machines */
		via_write(via2, vDirB, via_read(via2, vDirB) | 0x02);
	}
	via_write(via2, gBufB, via_read(via2, gBufB) | 0x02);

	/* disable nubus slot interrupts. */
	if (rbv_present) {
		via_write(via2, rSIER, 0x7F); /* like VIA; bit 7=clr,set */
		if ((via_read(via2, rSIER) & 0x7F) != 0) {
			printk("SIER not behaving properly: "
				"email <cananian@alumni.princeton.edu>\n");
		}
	} else {
		via_write(via2, vBufA, 0xFF); /* active low irqs, force high */
		via_write(via2, vDirA, 0xFF); /* ddr to output. */
	}
}

/*
 * The generic VIA interrupt routines (shamelessly stolen from Alan Cox's
 * via6522.c :-), disable/pending masks added.
 *
 * The new interrupt architecture in macints.c takes care of a lot of the
 * gruntwork for us, including tallying the interrupts and calling the
 * handlers on the linked list. All we need to do here is basically generate
 * the machspec interrupt number after clearing the interrupt.
 */

void via1_irq(int irq, void *dev_id, struct pt_regs *regs)
{
	int irq_bit, i;
	unsigned char events, mask;

	mask = via_read(via1, vIER) & 0x7f;
	events = via_read(via1, vIFR) & mask;
	if (events == 0) return;

	for (i = 0, irq_bit = 1 ; i < 7 ; i++, irq_bit <<= 1)
		if (events & irq_bit) {
			via_write(via1, vIER, irq_bit);
			via_write(via1, vIFR, irq_bit);
			mac_do_irq_list(VIA1_SOURCE_BASE + i, regs);
			via_write(via1, vIER, irq_bit | 0x80);
		}

	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? */
		via_irq_disable(IRQ_MAC_NUBUS);
		via_irq_clear(IRQ_MAC_NUBUS);
		mac_do_irq_list(IRQ_MAC_NUBUS, regs);
		via_irq_enable(IRQ_MAC_NUBUS);
	}
}

void via2_irq(int irq, void *dev_id, struct pt_regs *regs)
{
	int irq_bit, i;
	unsigned char events, mask;

	mask = via_read(via2, gIER) & 0x7f;
	events = via_read(via2, gIFR) & mask;
	if (events == 0) return;

	for (i = 0, irq_bit = 1 ; i < 7 ; i++, irq_bit <<= 1)
		if (events & irq_bit) {
			via_write(via2, gIER, irq_bit);
			via_write(via2, gIFR, irq_bit | rbv_clear);
			mac_do_irq_list(VIA2_SOURCE_BASE + i, regs);
			via_write(via2, gIER, irq_bit | 0x80);
		}
}

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

void via_nubus_irq(int irq, void *dev_id, struct pt_regs *regs)
{
	int irq_bit, i;
	unsigned char events;

	events = ~via_read(via2, gBufA) & nubus_active;
	if (events == 0) return;

	for (i = 0, irq_bit = 1 ; i < 7 ; i++, irq_bit <<= 1) {
		if (events & irq_bit) {
			via_irq_disable(NUBUS_SOURCE_BASE + i);
			/* FIXME: this does nothing.  Should we clear
                           the SLOTIRQ bit here? */
			via_irq_clear(NUBUS_SOURCE_BASE + i);
			mac_do_irq_list(NUBUS_SOURCE_BASE + i, regs);
			via_irq_enable(NUBUS_SOURCE_BASE + i);
		}
	}
}

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

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

	if (irq_src == 1) {
		via_write(via1, vIER, irq_bit | 0x80);
	} else if (irq_src == 2) {
		/*
		 * Set vPCR for SCSI interrupts (but not on RBV)
		 */
		if ((irq_idx == 0) && !rbv_present) {
			if (macintosh_config->scsi_type == MAC_SCSI_OLD) {
				/* CB2 (IRQ) indep. input, positive edge */
				/* CA2 (DRQ) indep. input, positive edge */
				via_write(via2, vPCR, 0x66);
			} else {
				/* CB2 (IRQ) indep. input, negative edge */
				/* CA2 (DRQ) indep. input, negative edge */
				via_write(via2, vPCR, 0x22);
			}
		}
		via_write(via2, gIER, irq_bit | 0x80);
	} else if (irq_src == 7) {
		if (rbv_present) {
			/* enable the slot interrupt. SIER works like IER. */
			via_write(via2, rSIER, IER_SET_BIT(irq_idx));
		} else {
			/* Make sure the bit is an input, to enable the irq */
			via_write(via2, vDirA,
					via_read(via2, vDirA) & ~irq_bit);
		}
		nubus_active |= irq_bit;
	}
}

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

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

	if (irq_src == 1) {
		via_write(via1, vIER, irq_bit);
	} else if (irq_src == 2) {
		via_write(via2, gIER, irq_bit);
	} else if (irq_src == 7) {
		if (rbv_present) {
			/* disable the slot interrupt.  SIER works like IER. */
			via_write(via2, rSIER, IER_CLR_BIT(irq_idx));
		} else {
			/* disable the nubus irq by changing dir to output */
			via_write(via2, vBufA, ~nubus_active);
			via_write(via2, vDirA, via_read(via2, vDirA) | irq_bit);
		}
		nubus_active &= ~irq_bit;
	}
}

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) {
		via_write(via1, vIFR, irq_bit);
	} else if (irq_src == 2) {
		via_write(via2, gIFR, irq_bit | rbv_clear);
	} else if (irq_src == 7) {
		/* FIXME: hmm.. */
	}
}

/*
 * 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 via_read(via1, vIFR) & irq_bit;
	} else if (irq_src == 2) {
		return via_read(via2, gIFR) & irq_bit;
	} else if (irq_src == 7) {
		return (~via_read(via2, gBufA)) & irq_bit;
	}
	return 0;
}

void via_scsi_clear(void)
{
	volatile unsigned char deep_magic;

#ifdef DEBUG_IRQUSE
	printk("via_scsi_clear()\n");
#endif

	/* We handle this in oss.c , but this gets called in mac_scsinew.c */
	if(oss_present) return;

	if (rbv_present) {
		via_write(via2, rIFR, (1<<3) | (1<<0) | rbv_clear);
		deep_magic = via_read(via2, rBufB);
	} else {
		deep_magic = via_read(via2, vBufB);
	}
	mac_enable_irq((IRQ_IDX(IRQ_MAC_SCSI)));
}

/*
 * PRAM/RTC access routines
 *
 * Must be called with interrupts disabled and
 * the RTC should be enabled.
 */

static __u8 via_pram_readbyte(void)
{
	int	i,reg;
	__u8	data;

	reg = via_read(via1, vBufB) & ~VIA1B_vRTCClk;

	/* Set the RTC data line to be an input. */

	via_write(via1, vDirB, via_read(via1, vDirB) & ~VIA1B_vRTCData);

	/* The bits of the byte come out in MSB order */

	data = 0;
	for (i = 0 ; i < 8 ; i++) {
		via_write(via1, vBufB, reg);
		via_write(via1, vBufB, reg | VIA1B_vRTCClk);
		data = (data << 1) | (via_read(via1, vBufB) & VIA1B_vRTCData);
	}

	/* Return RTC data line to output state */

	via_write(via1, vDirB, via_read(via1, vDirB) | VIA1B_vRTCData);

	return data;
}

static void via_pram_writebyte(__u8 data)
{
	int	i,reg,bit;

	reg = via_read(via1, vBufB) & ~(VIA1B_vRTCClk | VIA1B_vRTCData);

	/* The bits of the byte go in in MSB order */

	for (i = 0 ; i < 8 ; i++) {
		bit = data & 0x80? 1 : 0;
		data <<= 1;
		via_write(via1, vBufB, reg | bit);
		via_write(via1, vBufB, reg | bit | VIA1B_vRTCClk);
	}
}

/*
 * Execute a PRAM/RTC command. For read commands
 * data should point to a one-byte buffer for the
 * resulting data. For write commands it should point
 * to the data byte to for the command.
 *
 * This function disables all interrupts while running.
 */

void via_pram_command(int command, __u8 *data)
{
	unsigned long cpu_flags;
	int	is_read,tmp;

	save_flags(cpu_flags);
	cli();

	/* Enable the RTC and make sure the strobe line is high */

	tmp = (via_read(via1, vBufB) | VIA1B_vRTCClk) & ~VIA1B_vRTCEnb;
	via_write(via1, vBufB, tmp);

	if (command & 0xFF00) {		/* extended (two-byte) command */
		via_pram_writebyte((command & 0xFF00) >> 8);
		via_pram_writebyte(command & 0xFF);
		is_read = command & 0x8000;
	} else {			/* one-byte command */
		via_pram_writebyte(command);
		is_read = command & 0x80;
	}
	if (is_read) {
		*data = via_pram_readbyte();
	} else {
		via_pram_writebyte(*data);
	}

	/* All done, disable the RTC */

	via_write(via1, vBufB, via_read(via1, vBufB) | VIA1B_vRTCEnb);

	restore_flags(cpu_flags);
}

/*
 * Return the current time in seconds since January 1, 1904.
 *
 * This only works on machines with the VIA-based PRAM/RTC, which
 * is basically any machine with Mac II-style ADB.
 */

__u32 via_read_time(void)
{
	union {
		__u8  cdata[4];
		__u32 idata;
	} result, last_result;
	int	ct;

	/*
	 * The NetBSD guys say to loop until you get the same reading
	 * twice in a row.
	 */

	ct = 0;
	do {
		if (++ct > 10) {
			printk("via_read_time: couldn't get valid time, "
			       "last read = 0x%08X and 0x%08X\n", last_result.idata,
			       result.idata);
			break;
		}

		last_result.idata = result.idata;
		result.idata = 0;

		via_pram_command(0x81, &result.cdata[3]);
		via_pram_command(0x85, &result.cdata[2]);
		via_pram_command(0x89, &result.cdata[1]);
		via_pram_command(0x8D, &result.cdata[0]);
	} while (result.idata != last_result.idata);

	return result.idata;
}

/*
 * Set the current time to a number of seconds since January 1, 1904.
 *
 * This only works on machines with the VIA-based PRAM/RTC, which
 * is basically any machine with Mac II-style ADB.
 */

void via_write_time(__u32 time)
{
	union {
		__u8  cdata[4];
		__u32 idata;
	} data;
	__u8	temp;

	/* Clear the write protect bit */

	temp = 0x55;
	via_pram_command(0x35, &temp);

	data.idata = time;
	via_pram_command(0x01, &data.cdata[3]);
	via_pram_command(0x05, &data.cdata[2]);
	via_pram_command(0x09, &data.cdata[1]);
	via_pram_command(0x0D, &data.cdata[0]);

	/* Set the write protect bit */

	temp = 0xD5;
	via_pram_command(0x35, &temp);
}