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macints.c

/*
 *    Macintosh interrupts
 *
 * General design:
 * In contrary to the Amiga and Atari platforms, the Mac hardware seems to
 * exclusively use the autovector interrupts (the 'generic level0-level7'
 * interrupts with exception vectors 0x19-0x1f). The following interrupt levels
 * are used:
 *    1     - VIA1
 *            - slot 0: one second interrupt (CA2)
 *            - slot 1: VBlank (CA1)
 *            - slot 2: ADB data ready (SR full)
 *            - slot 3: ADB data  (CB2)
 *            - slot 4: ADB clock (CB1)
 *            - slot 5: timer 2
 *            - slot 6: timer 1
 *            - slot 7: status of IRQ; signals 'any enabled int.'
 *
 *    2     - VIA2 or RBV
 *            - slot 0: SCSI DRQ (CA2)
 *            - slot 1: NUBUS IRQ (CA1) need to read port A to find which
 *            - slot 2: /EXP IRQ (only on IIci)
 *            - slot 3: SCSI IRQ (CB2)
 *            - slot 4: ASC IRQ (CB1)
 *            - slot 5: timer 2 (not on IIci)
 *            - slot 6: timer 1 (not on IIci)
 *            - slot 7: status of IRQ; signals 'any enabled int.'
 *
 *    2     - OSS (IIfx only?)
 *            - slot 0: SCSI interrupt
 *            - slot 1: Sound interrupt
 *
 * Levels 3-6 vary by machine type. For VIA or RBV Macintoshes:
 *
 *    3     - unused (?)
 *
 *    4     - SCC (slot number determined by reading RR3 on the SSC itself)
 *            - slot 1: SCC channel A
 *            - slot 2: SCC channel B
 *
 *    5     - unused (?)
 *            [serial errors or special conditions seem to raise level 6
 *            interrupts on some models (LC4xx?)]
 *
 *    6     - off switch (?)
 *
 * For OSS Macintoshes (IIfx only at this point):
 *
 *    3     - Nubus interrupt
 *            - slot 0: Slot $9
 *            - slot 1: Slot $A
 *            - slot 2: Slot $B
 *            - slot 3: Slot $C
 *            - slot 4: Slot $D
 *            - slot 5: Slot $E
 *
 *    4     - SCC IOP
 *            - slot 1: SCC channel A
 *            - slot 2: SCC channel B
 *
 *    5     - ISM IOP (ADB?)
 *
 *    6     - unused
 *
 * For PSC Macintoshes (660AV, 840AV):
 *
 *    3     - PSC level 3
 *            - slot 0: MACE
 *
 *    4     - PSC level 4
 *            - slot 1: SCC channel A interrupt
 *            - slot 2: SCC channel B interrupt
 *            - slot 3: MACE DMA
 *
 *    5     - PSC level 5
 *
 *    6     - PSC level 6
 *
 * Finally we have good 'ole level 7, the non-maskable interrupt:
 *
 *    7     - NMI (programmer's switch on the back of some Macs)
 *            Also RAM parity error on models which support it (IIc, IIfx?)
 *
 * The current interrupt logic looks something like this:
 *
 * - We install dispatchers for the autovector interrupts (1-7). These
 *   dispatchers are responsible for querying the hardware (the
 *   VIA/RBV/OSS/PSC chips) to determine the actual interrupt source. Using
 *   this information a machspec interrupt number is generated by placing the
 *   index of the interrupt hardware into the low three bits and the original
 *   autovector interrupt number in the upper 5 bits. The handlers for the
 *   resulting machspec interrupt are then called.
 *
 * - Nubus is a special case because its interrupts are hidden behind two
 *   layers of hardware. Nubus interrupts come in as index 1 on VIA #2,
 *   which translates to IRQ number 17. In this spot we install _another_
 *   dispatcher. This dispatcher finds the interrupting slot number (9-F) and
 *   then forms a new machspec interrupt number as above with the slot number
 *   minus 9 in the low three bits and the pseudo-level 7 in the upper five
 *   bits.  The handlers for this new machspec interrupt number are then
 *   called. This puts Nubus interrupts into the range 56-62.
 *
 * - The Baboon interrupts (used on some PowerBooks) are an even more special
 *   case. They're hidden behind the Nubus slot $C interrupt thus adding a
 *   third layer of indirection. Why oh why did the Apple engineers do that?
 *
 * - We support "fast" and "slow" handlers, just like the Amiga port. The
 *   fast handlers are called first and with all interrupts disabled. They
 *   are expected to execute quickly (hence the name). The slow handlers are
 *   called last with interrupts enabled and the interrupt level restored.
 *   They must therefore be reentrant.
 *
 *   TODO:
 *
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/kernel_stat.h>
#include <linux/interrupt.h> /* for intr_count */
#include <linux/delay.h>
#include <linux/seq_file.h>

#include <asm/system.h>
#include <asm/irq.h>
#include <asm/traps.h>
#include <asm/bootinfo.h>
#include <asm/macintosh.h>
#include <asm/mac_via.h>
#include <asm/mac_psc.h>
#include <asm/hwtest.h>
#include <asm/errno.h>
#include <asm/macints.h>
#include <asm/irq_regs.h>
#include <asm/mac_oss.h>

#define DEBUG_SPURIOUS
#define SHUTUP_SONIC

/* SCC interrupt mask */

static int scc_mask;

/*
 * VIA/RBV hooks
 */

extern void via_register_interrupts(void);
extern void via_irq_enable(int);
extern void via_irq_disable(int);
extern void via_irq_clear(int);
extern int  via_irq_pending(int);

/*
 * OSS hooks
 */

extern void oss_register_interrupts(void);
extern void oss_irq_enable(int);
extern void oss_irq_disable(int);
extern void oss_irq_clear(int);
extern int  oss_irq_pending(int);

/*
 * PSC hooks
 */

extern void psc_register_interrupts(void);
extern void psc_irq_enable(int);
extern void psc_irq_disable(int);
extern void psc_irq_clear(int);
extern int  psc_irq_pending(int);

/*
 * IOP hooks
 */

extern void iop_register_interrupts(void);

/*
 * Baboon hooks
 */

extern int baboon_present;

extern void baboon_register_interrupts(void);
extern void baboon_irq_enable(int);
extern void baboon_irq_disable(int);
extern void baboon_irq_clear(int);

/*
 * SCC interrupt routines
 */

static void scc_irq_enable(unsigned int);
static void scc_irq_disable(unsigned int);

/*
 * console_loglevel determines NMI handler function
 */

irqreturn_t mac_nmi_handler(int, void *);
irqreturn_t mac_debug_handler(int, void *);

/* #define DEBUG_MACINTS */

void mac_enable_irq(unsigned int irq);
void mac_disable_irq(unsigned int irq);

static struct irq_controller mac_irq_controller = {
      .name       = "mac",
      .lock       = __SPIN_LOCK_UNLOCKED(mac_irq_controller.lock),
      .enable           = mac_enable_irq,
      .disable    = mac_disable_irq,
};

void __init mac_init_IRQ(void)
{
#ifdef DEBUG_MACINTS
      printk("mac_init_IRQ(): Setting things up...\n");
#endif
      scc_mask = 0;

      m68k_setup_irq_controller(&mac_irq_controller, IRQ_USER,
                          NUM_MAC_SOURCES - IRQ_USER);
      /* Make sure the SONIC interrupt is cleared or things get ugly */
#ifdef SHUTUP_SONIC
      printk("Killing onboard sonic... ");
      /* This address should hopefully be mapped already */
      if (hwreg_present((void*)(0x50f0a000))) {
            *(long *)(0x50f0a014) = 0x7fffL;
            *(long *)(0x50f0a010) = 0L;
      }
      printk("Done.\n");
#endif /* SHUTUP_SONIC */

      /*
       * Now register the handlers for the master IRQ handlers
       * at levels 1-7. Most of the work is done elsewhere.
       */

      if (oss_present)
            oss_register_interrupts();
      else
            via_register_interrupts();
      if (psc_present)
            psc_register_interrupts();
      if (baboon_present)
            baboon_register_interrupts();
      iop_register_interrupts();
      if (request_irq(IRQ_AUTO_7, mac_nmi_handler, 0, "NMI",
                  mac_nmi_handler))
            pr_err("Couldn't register NMI\n");
#ifdef DEBUG_MACINTS
      printk("mac_init_IRQ(): Done!\n");
#endif
}

/*
 *  mac_enable_irq - enable an interrupt source
 * mac_disable_irq - disable an interrupt source
 *   mac_clear_irq - clears a pending interrupt
 * mac_pending_irq - Returns the pending status of an IRQ (nonzero = pending)
 *
 * These routines are just dispatchers to the VIA/OSS/PSC routines.
 */

void mac_enable_irq(unsigned int irq)
{
      int irq_src = IRQ_SRC(irq);

      switch(irq_src) {
      case 1:
            via_irq_enable(irq);
            break;
      case 2:
      case 7:
            if (oss_present)
                  oss_irq_enable(irq);
            else
                  via_irq_enable(irq);
            break;
      case 3:
      case 4:
      case 5:
      case 6:
            if (psc_present)
                  psc_irq_enable(irq);
            else if (oss_present)
                  oss_irq_enable(irq);
            else if (irq_src == 4)
                  scc_irq_enable(irq);
            break;
      case 8:
            if (baboon_present)
                  baboon_irq_enable(irq);
            break;
      }
}

void mac_disable_irq(unsigned int irq)
{
      int irq_src = IRQ_SRC(irq);

      switch(irq_src) {
      case 1:
            via_irq_disable(irq);
            break;
      case 2:
      case 7:
            if (oss_present)
                  oss_irq_disable(irq);
            else
                  via_irq_disable(irq);
            break;
      case 3:
      case 4:
      case 5:
      case 6:
            if (psc_present)
                  psc_irq_disable(irq);
            else if (oss_present)
                  oss_irq_disable(irq);
            else if (irq_src == 4)
                  scc_irq_disable(irq);
            break;
      case 8:
            if (baboon_present)
                  baboon_irq_disable(irq);
            break;
      }
}

void mac_clear_irq(unsigned int irq)
{
      switch(IRQ_SRC(irq)) {
      case 1:
            via_irq_clear(irq);
            break;
      case 2:
      case 7:
            if (oss_present)
                  oss_irq_clear(irq);
            else
                  via_irq_clear(irq);
            break;
      case 3:
      case 4:
      case 5:
      case 6:
            if (psc_present)
                  psc_irq_clear(irq);
            else if (oss_present)
                  oss_irq_clear(irq);
            break;
      case 8:
            if (baboon_present)
                  baboon_irq_clear(irq);
            break;
      }
}

int mac_irq_pending(unsigned int irq)
{
      switch(IRQ_SRC(irq)) {
      case 1:
            return via_irq_pending(irq);
      case 2:
      case 7:
            if (oss_present)
                  return oss_irq_pending(irq);
            else
                  return via_irq_pending(irq);
      case 3:
      case 4:
      case 5:
      case 6:
            if (psc_present)
                  return psc_irq_pending(irq);
            else if (oss_present)
                  return oss_irq_pending(irq);
      }
      return 0;
}
EXPORT_SYMBOL(mac_irq_pending);

static int num_debug[8];

irqreturn_t mac_debug_handler(int irq, void *dev_id)
{
      if (num_debug[irq] < 10) {
            printk("DEBUG: Unexpected IRQ %d\n", irq);
            num_debug[irq]++;
      }
      return IRQ_HANDLED;
}

static int in_nmi;
static volatile int nmi_hold;

irqreturn_t mac_nmi_handler(int irq, void *dev_id)
{
      int i;
      /*
       * generate debug output on NMI switch if 'debug' kernel option given
       * (only works with Penguin!)
       */

      in_nmi++;
      for (i=0; i<100; i++)
            udelay(1000);

      if (in_nmi == 1) {
            nmi_hold = 1;
            printk("... pausing, press NMI to resume ...");
      } else {
            printk(" ok!\n");
            nmi_hold = 0;
      }

      barrier();

      while (nmi_hold == 1)
            udelay(1000);

      if (console_loglevel >= 8) {
#if 0
            struct pt_regs *fp = get_irq_regs();
            show_state();
            printk("PC: %08lx\nSR: %04x  SP: %p\n", fp->pc, fp->sr, fp);
            printk("d0: %08lx    d1: %08lx    d2: %08lx    d3: %08lx\n",
                   fp->d0, fp->d1, fp->d2, fp->d3);
            printk("d4: %08lx    d5: %08lx    a0: %08lx    a1: %08lx\n",
                   fp->d4, fp->d5, fp->a0, fp->a1);

            if (STACK_MAGIC != *(unsigned long *)current->kernel_stack_page)
                  printk("Corrupted stack page\n");
            printk("Process %s (pid: %d, stackpage=%08lx)\n",
                  current->comm, current->pid, current->kernel_stack_page);
            if (intr_count == 1)
                  dump_stack((struct frame *)fp);
#else
            /* printk("NMI "); */
#endif
      }
      in_nmi--;
      return IRQ_HANDLED;
}

/*
 * Simple routines for masking and unmasking
 * SCC interrupts in cases where this can't be
 * done in hardware (only the PSC can do that.)
 */

static void scc_irq_enable(unsigned int irq)
{
      int irq_idx = IRQ_IDX(irq);

      scc_mask |= (1 << irq_idx);
}

static void scc_irq_disable(unsigned int irq)
{
      int irq_idx = IRQ_IDX(irq);

      scc_mask &= ~(1 << irq_idx);
}

/*
 * SCC master interrupt handler. We have to do a bit of magic here
 * to figure out what channel gave us the interrupt; putting this
 * here is cleaner than hacking it into drivers/char/macserial.c.
 */

void mac_scc_dispatch(int irq, void *dev_id)
{
      volatile unsigned char *scc = (unsigned char *) mac_bi_data.sccbase + 2;
      unsigned char reg;
      unsigned long flags;

      /* Read RR3 from the chip. Always do this on channel A */
      /* This must be an atomic operation so disable irqs.   */

      local_irq_save(flags);
      *scc = 3;
      reg = *scc;
      local_irq_restore(flags);

      /* Now dispatch. Bits 0-2 are for channel B and */
      /* bits 3-5 are for channel A. We can safely    */
      /* ignore the remaining bits here.              */
      /*                                              */
      /* Note that we're ignoring scc_mask for now.   */
      /* If we actually mask the ints then we tend to */
      /* get hammered by very persistent SCC irqs,    */
      /* and since they're autovector interrupts they */
      /* pretty much kill the system.                 */

      if (reg & 0x38)
            m68k_handle_int(IRQ_SCCA);
      if (reg & 0x07)
            m68k_handle_int(IRQ_SCCB);
}

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