text: /*
   *	6522 Versatile Interface Adapter (VIA)
   *
   *	There are two of these on the Mac II. Some IRQs 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
   *
   * Additional data is here (the SY6522 was used in the Mac II etc):
   *     http://www.6502.org/documents/datasheets/synertek/synertek_sy6522.pdf
   *     http://www.6502.org/documents/datasheets/synertek/synertek_sy6522_programming_reference.pdf
   *
   * 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 <linux/module.h>
  #include <linux/irq.h>
  
  #include <asm/macintosh.h>
  #include <asm/macints.h>
  #include <asm/mac_via.h>
  #include <asm/mac_psc.h>
  #include <asm/mac_oss.h>
  
  volatile __u8 *via1, *via2;
  int rbv_present;
  int via_alt_mapping;
  EXPORT_SYMBOL(via_alt_mapping);
  static __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
   * _consistently_ lazy?                          - 1999-05-21 (jmt)
   */
  
  static int gIER,gIFR,gBufA,gBufB;
  
  /*
   * On Macs with a genuine VIA chip there is no way to mask an individual slot
   * interrupt. This limitation also seems to apply to VIA clone logic cores in
   * Quadra-like ASICs. (RBV and OSS machines don't have this limitation.)
   *
   * We used to fake it by configuring the relevant VIA pin as an output
   * (to mask the interrupt) or input (to unmask). That scheme did not work on
   * (at least) the Quadra 700. A NuBus card's /NMRQ signal is an open-collector
   * circuit (see Designing Cards and Drivers for Macintosh II and Macintosh SE,
   * p. 10-11 etc) but VIA outputs are not (see datasheet).
   *
   * Driving these outputs high must cause the VIA to source current and the
   * card to sink current when it asserts /NMRQ. Current will flow but the pin
   * voltage is uncertain and so the /NMRQ condition may still cause a transition
   * at the VIA2 CA1 input (which explains the lost interrupts). A side effect
   * is that a disabled slot IRQ can never be tested as pending or not.
   *
   * Driving these outputs low doesn't work either. All the slot /NMRQ lines are
   * (active low) OR'd together to generate the CA1 (aka "SLOTS") interrupt (see
   * The Guide To Macintosh Family Hardware, 2nd edition p. 167). If we drive a
   * disabled /NMRQ line low, the falling edge immediately triggers a CA1
   * interrupt and all slot interrupts after that will generate no transition
   * and therefore no interrupt, even after being re-enabled.
   *
   * So we make the VIA port A I/O lines inputs and use nubus_disabled to keep
   * track of their states. When any slot IRQ becomes disabled we mask the CA1
   * umbrella interrupt. Only when all slot IRQs become enabled do we unmask
   * the CA1 interrupt. It must remain enabled even when cards have no interrupt
   * handler registered. Drivers must therefore disable a slot interrupt at the
   * device before they call free_irq (like shared and autovector interrupts).
   *
   * There is also a related problem when MacOS is used to boot Linux. A network
   * card brought up by a MacOS driver may raise an interrupt while Linux boots.
   * This can be fatal since it can't be handled until the right driver loads
   * (if such a driver exists at all). Apparently related to this hardware
   * limitation, "Designing Cards and Drivers", p. 9-8, says that a slot
   * interrupt with no driver would crash MacOS (the book was written before
   * the appearance of Macs with RBV or OSS).
   */
  
  static u8 nubus_disabled;
  
  void via_debug_dump(void);
  
  /*
   * 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.
   */
  
  void __init 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(KERN_INFO "VIA1 at %p is a 6522 or clone\n", via1);
  
  	printk(KERN_INFO "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.
  	 */
  
  	via1[vIER] = 0x7F;
  	via1[vIFR] = 0x7F;
  	via1[vT1LL] = 0;
  	via1[vT1LH] = 0;
  	via1[vT1CL] = 0;
  	via1[vT1CH] = 0;
  	via1[vT2CL] = 0;
  	via1[vT2CH] = 0;
  	via1[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
  	via1[vACR] &= ~0x03; /* disable port A & B latches */
  
  	/*
  	 * SE/30: disable video IRQ
  	 * XXX: testing for SE/30 VBL
  	 */
  
  	if (macintosh_config->ident == MAC_MODEL_SE30) {
  		via1[vDirB] |= 0x40;
  		via1[vBufB] |= 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).
  	 */
  
  	via1[vDirB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk | VIA1B_vRTCData);
  	via1[vBufB] |= (VIA1B_vRTCEnb | VIA1B_vRTCClk);
  
  	/* Everything below this point is VIA2/RBV only... */
  
  	if (oss_present)
  		return;
  
  	if ((macintosh_config->via_type == MAC_VIA_QUADRA) &&
  	    (macintosh_config->adb_type != MAC_ADB_PB1) &&
  	    (macintosh_config->adb_type != MAC_ADB_PB2) &&
  	    (macintosh_config->ident    != MAC_MODEL_C660) &&
  	    (macintosh_config->ident    != MAC_MODEL_Q840)) {
  		via_alt_mapping = 1;
  		via1[vDirB] |= 0x40;
  		via1[vBufB] &= ~0x40;
  	} else {
  		via_alt_mapping = 0;
  	}
  
  	/*
  	 * Now initialize VIA2. For RBV we just kill all interrupts;
  	 * for a regular VIA we also reset the timers and stuff.
  	 */
  
  	via2[gIER] = 0x7F;
  	via2[gIFR] = 0x7F | rbv_clear;
  	if (!rbv_present) {
  		via2[vT1LL] = 0;
  		via2[vT1LH] = 0;
  		via2[vT1CL] = 0;
  		via2[vT1CH] = 0;
  		via2[vT2CL] = 0;
  		via2[vT2CH] = 0;
  		via2[vACR] &= ~0xC0; /* setup T1 timer with no PB7 output */
  		via2[vACR] &= ~0x03; /* disable port A & B latches */
  	}
  
  	/* Everything below this point is VIA2 only... */
  
  	if (rbv_present)
  		return;
  
  	/*
  	 * Set vPCR for control line interrupts.
  	 *
  	 * CA1 (SLOTS IRQ), CB1 (ASC IRQ): negative edge trigger.
  	 *
  	 * Macs with ESP SCSI have a negative edge triggered SCSI interrupt.
  	 * Testing reveals that PowerBooks do too. However, the SE/30
  	 * schematic diagram shows an active high NCR5380 IRQ line.
  	 */
  
  	pr_debug("VIA2 vPCR is 0x%02X\n", via2[vPCR]);
  	if (macintosh_config->via_type == MAC_VIA_II) {
  		/* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, pos. edge */
  		via2[vPCR] = 0x66;
  	} else {
  		/* CA2 (SCSI DRQ), CB2 (SCSI IRQ): indep. input, neg. edge */
  		via2[vPCR] = 0x22;
  	}
  }
  
  /*
   * Debugging dump, used in various places to see what's going on.
   */
  
  void via_debug_dump(void)
  {
  	printk(KERN_DEBUG "VIA1: DDRA = 0x%02X DDRB = 0x%02X ACR = 0x%02X\n",
  		(uint) via1[vDirA], (uint) via1[vDirB], (uint) via1[vACR]);
  	printk(KERN_DEBUG "         PCR = 0x%02X  IFR = 0x%02X IER = 0x%02X\n",
  		(uint) via1[vPCR], (uint) via1[vIFR], (uint) via1[vIER]);
  	if (oss_present) {
  		printk(KERN_DEBUG "VIA2: <OSS>\n");
  	} else if (rbv_present) {
  		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]);
  	}
  }
  
  /*
   * Flush the L2 cache on Macs that have it by flipping
   * the system into 24-bit mode for an instant.
   */
  
  void via_l2_flush(int writeback)
  {
  	unsigned long flags;
  
  	local_irq_save(flags);
  	via2[gBufB] &= ~VIA2B_vMode32;
  	via2[gBufB] |= VIA2B_vMode32;
  	local_irq_restore(flags);
  }
  
  /*
   * 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 the slot interrupts. On some hardware that's not possible.
  	 * On some hardware it's unclear what all of these I/O lines do.
  	 */
  
  	switch (macintosh_config->via_type) {
  	case MAC_VIA_II:
  	case MAC_VIA_QUADRA:
  		pr_debug("VIA2 vDirA is 0x%02X\n", via2[vDirA]);
  		break;
  	case MAC_VIA_IICI:
  		/* RBV. Disable all the slot interrupts. SIER works like IER. */
  		via2[rSIER] = 0x7F;
  		break;
  	}
  }
  
  void via_nubus_irq_startup(int irq)
  {
  	int irq_idx = IRQ_IDX(irq);
  
  	switch (macintosh_config->via_type) {
  	case MAC_VIA_II:
  	case MAC_VIA_QUADRA:
  		/* Make the port A line an input. Probably redundant. */
  		if (macintosh_config->via_type == MAC_VIA_II) {
  			/* The top two bits are RAM size outputs. */
  			via2[vDirA] &= 0xC0 | ~(1 << irq_idx);
  		} else {
  			/* Allow NuBus slots 9 through F. */
  			via2[vDirA] &= 0x80 | ~(1 << irq_idx);
  		}
  		/* fall through */
  	case MAC_VIA_IICI:
  		via_irq_enable(irq);
  		break;
  	}
  }
  
  void via_nubus_irq_shutdown(int irq)
  {
  	switch (macintosh_config->via_type) {
  	case MAC_VIA_II:
  	case MAC_VIA_QUADRA:
  		/* Ensure that the umbrella CA1 interrupt remains enabled. */
  		via_irq_enable(irq);
  		break;
  	case MAC_VIA_IICI:
  		via_irq_disable(irq);
  		break;
  	}
  }
  
  /*
   * The generic VIA interrupt routines (shamelessly stolen from Alan Cox's
   * via6522.c :-), disable/pending masks added.
   */
  
  #define VIA_TIMER_1_INT BIT(6)
  
  void via1_irq(struct irq_desc *desc)
  {
  	int irq_num;
  	unsigned char irq_bit, events;
  
  	events = via1[vIFR] & via1[vIER] & 0x7F;
  	if (!events)
  		return;
  
  	irq_num = IRQ_MAC_TIMER_1;
  	irq_bit = VIA_TIMER_1_INT;
  	if (events & irq_bit) {
  		unsigned long flags;
  
  		local_irq_save(flags);
  		via1[vIFR] = irq_bit;
  		generic_handle_irq(irq_num);
  		local_irq_restore(flags);
  
  		events &= ~irq_bit;
  		if (!events)
  			return;
  	}
  
  	irq_num = VIA1_SOURCE_BASE;
  	irq_bit = 1;
  	do {
  		if (events & irq_bit) {
  			via1[vIFR] = irq_bit;
  			generic_handle_irq(irq_num);
  		}
  		++irq_num;
  		irq_bit <<= 1;
  	} while (events >= irq_bit);
  }
  
  static void via2_irq(struct irq_desc *desc)
  {
  	int irq_num;
  	unsigned char irq_bit, events;
  
  	events = via2[gIFR] & via2[gIER] & 0x7F;
  	if (!events)
  		return;
  
  	irq_num = VIA2_SOURCE_BASE;
  	irq_bit = 1;
  	do {
  		if (events & irq_bit) {
  			via2[gIFR] = irq_bit | rbv_clear;
  			generic_handle_irq(irq_num);
  		}
  		++irq_num;
  		irq_bit <<= 1;
  	} while (events >= irq_bit);
  }
  
  /*
   * Dispatch Nubus interrupts. We are called as a secondary dispatch by the
   * VIA2 dispatcher as a fast interrupt handler.
   */
  
  static void via_nubus_irq(struct irq_desc *desc)
  {
  	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;
  
  	do {
  		slot_irq = IRQ_NUBUS_F;
  		slot_bit = 0x40;
  		do {
  			if (events & slot_bit) {
  				events &= ~slot_bit;
  				generic_handle_irq(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);
  }
  
  /*
   * Register the interrupt dispatchers for VIA or RBV machines only.
   */
  
  void __init via_register_interrupts(void)
  {
  	if (via_alt_mapping) {
  		/* software interrupt */
  		irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
  		/* via1 interrupt */
  		irq_set_chained_handler(IRQ_AUTO_6, via1_irq);
  	} else {
  		irq_set_chained_handler(IRQ_AUTO_1, via1_irq);
  	}
  	irq_set_chained_handler(IRQ_AUTO_2, via2_irq);
  	irq_set_chained_handler(IRQ_MAC_NUBUS, via_nubus_irq);
  }
  
  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:
  		case MAC_VIA_QUADRA:
  			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;
  		}
  	}
  }
  
  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:
  		case MAC_VIA_QUADRA:
  			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;
  		}
  	}
  }
  
  void via1_set_head(int head)
  {
  	if (head == 0)
  		via1[vBufA] &= ~VIA1A_vHeadSel;
  	else
  		via1[vBufA] |= VIA1A_vHeadSel;
  }
  EXPORT_SYMBOL(via1_set_head);
  
  int via2_scsi_drq_pending(void)
  {
  	return via2[gIFR] & (1 << IRQ_IDX(IRQ_MAC_SCSIDRQ));
  }
  EXPORT_SYMBOL(via2_scsi_drq_pending);
  
  /* timer and clock source */
  
  #define VIA_CLOCK_FREQ     783360                /* VIA "phase 2" clock in Hz */
  #define VIA_TIMER_INTERVAL (1000000 / HZ)        /* microseconds per jiffy */
  #define VIA_TIMER_CYCLES   (VIA_CLOCK_FREQ / HZ) /* clock cycles per jiffy */
  
  #define VIA_TC             (VIA_TIMER_CYCLES - 2) /* including 0 and -1 */
  #define VIA_TC_LOW         (VIA_TC & 0xFF)
  #define VIA_TC_HIGH        (VIA_TC >> 8)
  
  void __init via_init_clock(irq_handler_t timer_routine)
  {
  	if (request_irq(IRQ_MAC_TIMER_1, timer_routine, 0, "timer", NULL)) {
  		pr_err("Couldn't register %s interrupt\n", "timer");
  		return;
  	}
  
  	via1[vT1LL] = VIA_TC_LOW;
  	via1[vT1LH] = VIA_TC_HIGH;
  	via1[vT1CL] = VIA_TC_LOW;
  	via1[vT1CH] = VIA_TC_HIGH;
  	via1[vACR] |= 0x40;
  }
  
  u32 mac_gettimeoffset(void)
  {
  	unsigned long flags;
  	u8 count_high;
  	u16 count, offset = 0;
  
  	/*
  	 * Timer counter wrap-around is detected with the timer interrupt flag
  	 * but reading the counter low byte (vT1CL) would reset the flag.
  	 * Also, accessing both counter registers is essentially a data race.
  	 * These problems are avoided by ignoring the low byte. Clock accuracy
  	 * is 256 times worse (error can reach 0.327 ms) but CPU overhead is
  	 * reduced by avoiding slow VIA register accesses.
  	 */
  
  	local_irq_save(flags);
  	count_high = via1[vT1CH];
  	if (count_high == 0xFF)
  		count_high = 0;
  	if (count_high > 0 && (via1[vIFR] & VIA_TIMER_1_INT))
  		offset = VIA_TIMER_CYCLES;
  	local_irq_restore(flags);
  
  	count = count_high << 8;
  	count = VIA_TIMER_CYCLES - count + offset;
  
  	return ((count * VIA_TIMER_INTERVAL) / VIA_TIMER_CYCLES) * 1000;
  }
  