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oss.c

/*
 *    OSS handling
 *    Written by Joshua M. Thompson (funaho@jurai.org)
 *
 *
 *    This chip is used in the IIfx in place of VIA #2. It acts like a fancy
 *    VIA chip with prorammable interrupt levels.
 *
 * 990502 (jmt) - Major rewrite for new interrupt architecture as well as some
 *            recent insights into OSS operational details.
 * 990610 (jmt) - Now taking full advantage of the OSS. Interrupts are mapped
 *            to mostly match the A/UX interrupt scheme supported on the
 *            VIA side. Also added support for enabling the ISM irq again
 *            since we now have a functional IOP manager.
 */

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

int oss_present;
volatile struct mac_oss *oss;

static irqreturn_t oss_irq(int, void *);
static irqreturn_t oss_nubus_irq(int, void *);

extern irqreturn_t via1_irq(int, void *);
extern irqreturn_t mac_scc_dispatch(int, void *);

/*
 * Initialize the OSS
 *
 * The OSS "detection" code is actually in via_init() which is always called
 * before us. Thus we can count on oss_present being valid on entry.
 */

void __init oss_init(void)
{
      int i;

      if (!oss_present) return;

      oss = (struct mac_oss *) OSS_BASE;

      /* Disable all interrupts. Unlike a VIA it looks like we    */
      /* do this by setting the source's interrupt level to zero. */

      for (i = 0; i <= OSS_NUM_SOURCES; i++) {
            oss->irq_level[i] = OSS_IRQLEV_DISABLED;
      }
      /* If we disable VIA1 here, we never really handle it... */
      oss->irq_level[OSS_VIA1] = OSS_IRQLEV_VIA1;
}

/*
 * Register the OSS and NuBus interrupt dispatchers.
 */

void __init oss_register_interrupts(void)
{
      request_irq(OSS_IRQLEV_SCSI, oss_irq, IRQ_FLG_LOCK,
                  "scsi", (void *) oss);
      request_irq(OSS_IRQLEV_IOPSCC, mac_scc_dispatch, IRQ_FLG_LOCK,
                  "scc", mac_scc_dispatch);
      request_irq(OSS_IRQLEV_NUBUS, oss_nubus_irq, IRQ_FLG_LOCK,
                  "nubus", (void *) oss);
      request_irq(OSS_IRQLEV_SOUND, oss_irq, IRQ_FLG_LOCK,
                  "sound", (void *) oss);
      request_irq(OSS_IRQLEV_VIA1, via1_irq, IRQ_FLG_LOCK,
                  "via1", (void *) via1);
}

/*
 * Initialize OSS for Nubus access
 */

void __init oss_nubus_init(void)
{
}

/*
 * Handle miscellaneous OSS interrupts. Right now that's just sound
 * and SCSI; everything else is routed to its own autovector IRQ.
 */

static irqreturn_t oss_irq(int irq, void *dev_id)
{
      int events;

      events = oss->irq_pending & (OSS_IP_SOUND|OSS_IP_SCSI);
      if (!events)
            return IRQ_NONE;

#ifdef DEBUG_IRQS
      if ((console_loglevel == 10) && !(events & OSS_IP_SCSI)) {
            printk("oss_irq: irq %d events = 0x%04X\n", irq,
                  (int) oss->irq_pending);
      }
#endif
      /* FIXME: how do you clear a pending IRQ?    */

      if (events & OSS_IP_SOUND) {
            oss->irq_pending &= ~OSS_IP_SOUND;
            /* FIXME: call sound handler */
      } else if (events & OSS_IP_SCSI) {
            oss->irq_pending &= ~OSS_IP_SCSI;
            m68k_handle_int(IRQ_MAC_SCSI);
      } else {
            /* FIXME: error check here? */
      }
      return IRQ_HANDLED;
}

/*
 * Nubus IRQ handler, OSS style
 *
 * Unlike the VIA/RBV this is on its own autovector interrupt level.
 */

static irqreturn_t oss_nubus_irq(int irq, void *dev_id)
{
      int events, irq_bit, i;

      events = oss->irq_pending & OSS_IP_NUBUS;
      if (!events)
            return IRQ_NONE;

#ifdef DEBUG_NUBUS_INT
      if (console_loglevel > 7) {
            printk("oss_nubus_irq: events = 0x%04X\n", events);
      }
#endif
      /* There are only six slots on the OSS, not seven */

      i = 6;
      irq_bit = 0x40;
      do {
            --i;
            irq_bit >>= 1;
            if (events & irq_bit) {
                  oss->irq_pending &= ~irq_bit;
                  m68k_handle_int(NUBUS_SOURCE_BASE + i);
            }
      } while(events & (irq_bit - 1));
      return IRQ_HANDLED;
}

/*
 * Enable an OSS interrupt
 *
 * It looks messy but it's rather straightforward. The switch() statement
 * just maps the machspec interrupt numbers to the right OSS interrupt
 * source (if the OSS handles that interrupt) and then sets the interrupt
 * level for that source to nonzero, thus enabling the interrupt.
 */

void oss_irq_enable(int irq) {
#ifdef DEBUG_IRQUSE
      printk("oss_irq_enable(%d)\n", irq);
#endif
      switch(irq) {
            case IRQ_SCC:
            case IRQ_SCCA:
            case IRQ_SCCB:
                  oss->irq_level[OSS_IOPSCC] = OSS_IRQLEV_IOPSCC;
                  break;
            case IRQ_MAC_ADB:
                  oss->irq_level[OSS_IOPISM] = OSS_IRQLEV_IOPISM;
                  break;
            case IRQ_MAC_SCSI:
                  oss->irq_level[OSS_SCSI] = OSS_IRQLEV_SCSI;
                  break;
            case IRQ_NUBUS_9:
            case IRQ_NUBUS_A:
            case IRQ_NUBUS_B:
            case IRQ_NUBUS_C:
            case IRQ_NUBUS_D:
            case IRQ_NUBUS_E:
                  irq -= NUBUS_SOURCE_BASE;
                  oss->irq_level[irq] = OSS_IRQLEV_NUBUS;
                  break;
#ifdef DEBUG_IRQUSE
            default:
                  printk("%s unknown irq %d\n", __func__, irq);
                  break;
#endif
      }
}

/*
 * Disable an OSS interrupt
 *
 * Same as above except we set the source's interrupt level to zero,
 * to disable the interrupt.
 */

void oss_irq_disable(int irq) {
#ifdef DEBUG_IRQUSE
      printk("oss_irq_disable(%d)\n", irq);
#endif
      switch(irq) {
            case IRQ_SCC:
            case IRQ_SCCA:
            case IRQ_SCCB:
                  oss->irq_level[OSS_IOPSCC] = OSS_IRQLEV_DISABLED;
                  break;
            case IRQ_MAC_ADB:
                  oss->irq_level[OSS_IOPISM] = OSS_IRQLEV_DISABLED;
                  break;
            case IRQ_MAC_SCSI:
                  oss->irq_level[OSS_SCSI] = OSS_IRQLEV_DISABLED;
                  break;
            case IRQ_NUBUS_9:
            case IRQ_NUBUS_A:
            case IRQ_NUBUS_B:
            case IRQ_NUBUS_C:
            case IRQ_NUBUS_D:
            case IRQ_NUBUS_E:
                  irq -= NUBUS_SOURCE_BASE;
                  oss->irq_level[irq] = OSS_IRQLEV_DISABLED;
                  break;
#ifdef DEBUG_IRQUSE
            default:
                  printk("%s unknown irq %d\n", __func__, irq);
                  break;
#endif
      }
}

/*
 * Clear an OSS interrupt
 *
 * Not sure if this works or not but it's the only method I could
 * think of based on the contents of the mac_oss structure.
 */

void oss_irq_clear(int irq) {
      /* FIXME: how to do this on OSS? */
      switch(irq) {
            case IRQ_SCC:
            case IRQ_SCCA:
            case IRQ_SCCB:
                  oss->irq_pending &= ~OSS_IP_IOPSCC;
                  break;
            case IRQ_MAC_ADB:
                  oss->irq_pending &= ~OSS_IP_IOPISM;
                  break;
            case IRQ_MAC_SCSI:
                  oss->irq_pending &= ~OSS_IP_SCSI;
                  break;
            case IRQ_NUBUS_9:
            case IRQ_NUBUS_A:
            case IRQ_NUBUS_B:
            case IRQ_NUBUS_C:
            case IRQ_NUBUS_D:
            case IRQ_NUBUS_E:
                  irq -= NUBUS_SOURCE_BASE;
                  oss->irq_pending &= ~(1 << irq);
                  break;
      }
}

/*
 * Check to see if a specific OSS interrupt is pending
 */

int oss_irq_pending(int irq)
{
      switch(irq) {
            case IRQ_SCC:
            case IRQ_SCCA:
            case IRQ_SCCB:
                  return oss->irq_pending & OSS_IP_IOPSCC;
                  break;
            case IRQ_MAC_ADB:
                  return oss->irq_pending & OSS_IP_IOPISM;
                  break;
            case IRQ_MAC_SCSI:
                  return oss->irq_pending & OSS_IP_SCSI;
                  break;
            case IRQ_NUBUS_9:
            case IRQ_NUBUS_A:
            case IRQ_NUBUS_B:
            case IRQ_NUBUS_C:
            case IRQ_NUBUS_D:
            case IRQ_NUBUS_E:
                  irq -= NUBUS_SOURCE_BASE;
                  return oss->irq_pending & (1 << irq);
                  break;
      }
      return 0;
}

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