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via.c

/*
 *    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 <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;
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;

/*
 * 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)

/* To disable a NuBus slot on Quadras we make the slot IRQ lines outputs, set
 * high. On RBV we just use the slot interrupt enable register. On Macs with
 * genuine VIA chips we must use nubus_disabled to keep track of disabled slot
 * interrupts. When any slot IRQ is disabled we mask the (edge triggered) CA1
 * or "SLOTS" interrupt. When no slot is disabled, we unmask the CA1 interrupt.
 * So, on genuine VIAs, having more than one NuBus IRQ can mean trouble,
 * because closing one of those drivers can mask all of the NuBus interrupts.
 * Also, since we can't mask the unregistered slot IRQs on genuine VIAs, it's
 * possible to get interrupts from cards that MacOS or the ROM has configured
 * but we have not. FWIW, "Designing Cards and Drivers for Macintosh II and
 * Macintosh SE", page 9-8, says, a slot IRQ with no driver would crash MacOS.
 */
static u8 nubus_disabled;

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

extern irqreturn_t mac_scc_dispatch(int, void *);
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.
 */

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] &= 0x3F;
      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 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_P475:
            case MAC_MODEL_P475F:
            case MAC_MODEL_P575:
            case MAC_MODEL_Q605:
            case MAC_MODEL_Q605_ACC:
            case MAC_MODEL_C610:
            case MAC_MODEL_Q610:
            case MAC_MODEL_Q630:
            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;
                  via1[vDirB] |= 0x40;
                  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.
       */

      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] &= 0x3F;
            via2[vACR] &= ~0x03; /* disable port A & B latches */
      }

      /*
       * Set vPCR for SCSI interrupts (but not on RBV)
       */
      if (!rbv_present) {
            if (macintosh_config->scsi_type == MAC_SCSI_OLD) {
                  /* CB2 (IRQ) indep. input, positive edge */
                  /* CA2 (DRQ) indep. input, positive edge */
                  via2[vPCR] = 0x66;
            } else {
                  /* CB2 (IRQ) indep. input, negative edge */
                  /* CA2 (DRQ) indep. input, negative edge */
                  via2[vPCR] = 0x22;
            }
      }
}

/*
 * Start the 100 Hz clock
 */

void __init via_init_clock(irq_handler_t func)
{
      via1[vACR] |= 0x40;
      via1[vT1LL] = MAC_CLOCK_LOW;
      via1[vT1LH] = MAC_CLOCK_HIGH;
      via1[vT1CL] = MAC_CLOCK_LOW;
      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.
 */

void __init via_register_interrupts(void)
{
      if (via_alt_mapping) {
            request_irq(IRQ_AUTO_1, via1_irq,
                        IRQ_FLG_LOCK|IRQ_FLG_FAST, "software",
                        (void *) via1);
            request_irq(IRQ_AUTO_6, via1_irq,
                        IRQ_FLG_LOCK|IRQ_FLG_FAST, "via1",
                        (void *) via1);
      } else {
            request_irq(IRQ_AUTO_1, via1_irq,
                        IRQ_FLG_LOCK|IRQ_FLG_FAST, "via1",
                        (void *) via1);
      }
      request_irq(IRQ_AUTO_2, via2_irq, IRQ_FLG_LOCK|IRQ_FLG_FAST,
                  "via2", (void *) via2);
      if (!psc_present) {
            request_irq(IRQ_AUTO_4, mac_scc_dispatch, IRQ_FLG_LOCK,
                        "scc", mac_scc_dispatch);
      }
      request_irq(IRQ_MAC_NUBUS, via_nubus_irq, IRQ_FLG_LOCK|IRQ_FLG_FAST,
                  "nubus", (void *) via2);
}

/*
 * 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]);
      }
}

/*
 * 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;
}

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