q40ints.c

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/*
 * arch/m68k/q40/q40ints.c
 *
 * Copyright (C) 1999,2001 Richard Zidlicky
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 *
 * .. used to be loosely based on bvme6000ints.c
 *
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/irq.h>

#include <asm/ptrace.h>
#include <asm/traps.h>

#include <asm/q40_master.h>
#include <asm/q40ints.h>

/*
 * Q40 IRQs are defined as follows:
 *            3,4,5,6,7,10,11,14,15 : ISA dev IRQs
 *            16-31: reserved
 *            32   : keyboard int
 *            33   : frame int (50/200 Hz periodic timer)
 *            34   : sample int (10/20 KHz periodic timer)
 *
*/

static void q40_irq_handler(unsigned int, struct pt_regs *fp);
static void q40_irq_enable(struct irq_data *data);
static void q40_irq_disable(struct irq_data *data);

unsigned short q40_ablecount[35];
unsigned short q40_state[35];

static unsigned int q40_irq_startup(struct irq_data *data)
{
    unsigned int irq = data->irq;

    /* test for ISA ints not implemented by HW */
    switch (irq) {
    case 1: case 2: case 8: case 9:
    case 11: case 12: case 13:
        printk("%s: ISA IRQ %d not implemented by HW\n", __func__, irq);
        /* FIXME return -ENXIO; */
    }
    return 0;
}

static void q40_irq_shutdown(struct irq_data *data)
{
}

static struct irq_chip q40_irq_chip = {
    .name       = "q40",
    .irq_startup    = q40_irq_startup,
    .irq_shutdown   = q40_irq_shutdown,
    .irq_enable = q40_irq_enable,
    .irq_disable    = q40_irq_disable,
};

/*
 * void q40_init_IRQ (void)
 *
 * Parameters:  None
 *
 * Returns: Nothing
 *
 * This function is called during kernel startup to initialize
 * the q40 IRQ handling routines.
 */

static int disabled;

void __init q40_init_IRQ(void)
{
    m68k_setup_irq_controller(&q40_irq_chip, handle_simple_irq, 1,
                  Q40_IRQ_MAX);

    /* setup handler for ISA ints */
    m68k_setup_auto_interrupt(q40_irq_handler);

    m68k_irq_startup_irq(IRQ_AUTO_2);
    m68k_irq_startup_irq(IRQ_AUTO_4);

    /* now enable some ints.. */
    master_outb(1, EXT_ENABLE_REG);  /* ISA IRQ 5-15 */

    /* make sure keyboard IRQ is disabled */
    master_outb(0, KEY_IRQ_ENABLE_REG);
}


/*
 * this stuff doesn't really belong here..
 */

int ql_ticks;              /* 200Hz ticks since last jiffie */
static int sound_ticks;

#define SVOL 45

void q40_mksound(unsigned int hz, unsigned int ticks)
{
    /* for now ignore hz, except that hz==0 switches off sound */
    /* simply alternate the ampl (128-SVOL)-(128+SVOL)-..-.. at 200Hz */
    if (hz == 0) {
        if (sound_ticks)
            sound_ticks = 1;

        *DAC_LEFT = 128;
        *DAC_RIGHT = 128;

        return;
    }
    /* sound itself is done in q40_timer_int */
    if (sound_ticks == 0)
        sound_ticks = 1000; /* pretty long beep */
    sound_ticks = ticks << 1;
}

static irq_handler_t q40_timer_routine;

static irqreturn_t q40_timer_int (int irq, void * dev)
{
    ql_ticks = ql_ticks ? 0 : 1;
    if (sound_ticks) {
        unsigned char sval=(sound_ticks & 1) ? 128-SVOL : 128+SVOL;
        sound_ticks--;
        *DAC_LEFT=sval;
        *DAC_RIGHT=sval;
    }

    if (!ql_ticks)
        q40_timer_routine(irq, dev);
    return IRQ_HANDLED;
}

void q40_sched_init (irq_handler_t timer_routine)
{
    int timer_irq;

    q40_timer_routine = timer_routine;
    timer_irq = Q40_IRQ_FRAME;

    if (request_irq(timer_irq, q40_timer_int, 0,
                "timer", q40_timer_int))
        panic("Couldn't register timer int");

    master_outb(-1, FRAME_CLEAR_REG);
    master_outb( 1, FRAME_RATE_REG);
}


/*
 * tables to translate bits into IRQ numbers
 * it is a good idea to order the entries by priority
 *
*/

struct IRQ_TABLE{ unsigned mask; int irq ;};
#if 0
static struct IRQ_TABLE iirqs[]={
  {Q40_IRQ_FRAME_MASK,Q40_IRQ_FRAME},
  {Q40_IRQ_KEYB_MASK,Q40_IRQ_KEYBOARD},
  {0,0}};
#endif
static struct IRQ_TABLE eirqs[] = {
  { .mask = Q40_IRQ3_MASK,  .irq = 3 }, /* ser 1 */
  { .mask = Q40_IRQ4_MASK,  .irq = 4 }, /* ser 2 */
  { .mask = Q40_IRQ14_MASK, .irq = 14 },    /* IDE 1 */
  { .mask = Q40_IRQ15_MASK, .irq = 15 },    /* IDE 2 */
  { .mask = Q40_IRQ6_MASK,  .irq = 6 }, /* floppy, handled elsewhere */
  { .mask = Q40_IRQ7_MASK,  .irq = 7 }, /* par */
  { .mask = Q40_IRQ5_MASK,  .irq = 5 },
  { .mask = Q40_IRQ10_MASK, .irq = 10 },
  {0,0}
};

/* complain only this many times about spurious ints : */
static int ccleirq=60;    /* ISA dev IRQs*/
/*static int cclirq=60;*/     /* internal */

/* FIXME: add shared ints,mask,unmask,probing.... */

#define IRQ_INPROGRESS 1
/*static unsigned short saved_mask;*/
//static int do_tint=0;

#define DEBUG_Q40INT
/*#define IP_USE_DISABLE *//* would be nice, but crashes ???? */

static int mext_disabled=0;  /* ext irq disabled by master chip? */
static int aliased_irq=0;  /* how many times inside handler ?*/


/* got interrupt, dispatch to ISA or keyboard/timer IRQs */
static void q40_irq_handler(unsigned int irq, struct pt_regs *fp)
{
    unsigned mir, mer;
    int i;

//repeat:
    mir = master_inb(IIRQ_REG);
#ifdef CONFIG_BLK_DEV_FD
    if ((mir & Q40_IRQ_EXT_MASK) &&
        (master_inb(EIRQ_REG) & Q40_IRQ6_MASK)) {
        floppy_hardint();
        return;
    }
#endif
    switch (irq) {
    case 4:
    case 6:
        do_IRQ(Q40_IRQ_SAMPLE, fp);
        return;
    }
    if (mir & Q40_IRQ_FRAME_MASK) {
        do_IRQ(Q40_IRQ_FRAME, fp);
        master_outb(-1, FRAME_CLEAR_REG);
    }
    if ((mir & Q40_IRQ_SER_MASK) || (mir & Q40_IRQ_EXT_MASK)) {
        mer = master_inb(EIRQ_REG);
        for (i = 0; eirqs[i].mask; i++) {
            if (mer & eirqs[i].mask) {
                irq = eirqs[i].irq;
/*
 * There is a little mess wrt which IRQ really caused this irq request. The
 * main problem is that IIRQ_REG and EIRQ_REG reflect the state when they
 * are read - which is long after the request came in. In theory IRQs should
 * not just go away but they occasionally do
 */
                if (irq > 4 && irq <= 15 && mext_disabled) {
                    /*aliased_irq++;*/
                    goto iirq;
                }
                if (q40_state[irq] & IRQ_INPROGRESS) {
                    /* some handlers do local_irq_enable() for irq latency reasons, */
                    /* however reentering an active irq handler is not permitted */
#ifdef IP_USE_DISABLE
                    /* in theory this is the better way to do it because it still */
                    /* lets through eg the serial irqs, unfortunately it crashes */
                    disable_irq(irq);
                    disabled = 1;
#else
                    /*printk("IRQ_INPROGRESS detected for irq %d, disabling - %s disabled\n",
                        irq, disabled ? "already" : "not yet"); */
                    fp->sr = (((fp->sr) & (~0x700))+0x200);
                    disabled = 1;
#endif
                    goto iirq;
                }
                q40_state[irq] |= IRQ_INPROGRESS;
                do_IRQ(irq, fp);
                q40_state[irq] &= ~IRQ_INPROGRESS;

                /* naively enable everything, if that fails than    */
                /* this function will be reentered immediately thus */
                /* getting another chance to disable the IRQ        */

                if (disabled) {
#ifdef IP_USE_DISABLE
                    if (irq > 4) {
                        disabled = 0;
                        enable_irq(irq);
                    }
#else
                    disabled = 0;
                    /*printk("reenabling irq %d\n", irq); */
#endif
                }
// used to do 'goto repeat;' here, this delayed bh processing too long
                return;
            }
        }
        if (mer && ccleirq > 0 && !aliased_irq) {
            printk("ISA interrupt from unknown source? EIRQ_REG = %x\n",mer);
            ccleirq--;
        }
    }
 iirq:
    mir = master_inb(IIRQ_REG);
    /* should test whether keyboard irq is really enabled, doing it in defhand */
    if (mir & Q40_IRQ_KEYB_MASK)
        do_IRQ(Q40_IRQ_KEYBOARD, fp);

    return;
}

void q40_irq_enable(struct irq_data *data)
{
    unsigned int irq = data->irq;

    if (irq >= 5 && irq <= 15) {
        mext_disabled--;
        if (mext_disabled > 0)
            printk("q40_irq_enable : nested disable/enable\n");
        if (mext_disabled == 0)
            master_outb(1, EXT_ENABLE_REG);
    }
}


void q40_irq_disable(struct irq_data *data)
{
    unsigned int irq = data->irq;

    /* disable ISA iqs : only do something if the driver has been
     * verified to be Q40 "compatible" - right now IDE, NE2K
     * Any driver should not attempt to sleep across disable_irq !!
     */

    if (irq >= 5 && irq <= 15) {
        master_outb(0, EXT_ENABLE_REG);
        mext_disabled++;
        if (mext_disabled > 1)
            printk("disable_irq nesting count %d\n",mext_disabled);
    }
}