Archipelago » qemu

/*

 * QEMU 8259 interrupt controller emulation

 * 

 * Copyright (c) 2003-2004 Fabrice Bellard

 * 

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

 * THE SOFTWARE.

 */

#include "vl.h"

/* debug PIC */

//#define DEBUG_PIC

//#define DEBUG_IRQ_LATENCY

typedef struct PicState {

    uint8_t last_irr; /* edge detection */

    uint8_t irr; /* interrupt request register */

    uint8_t imr; /* interrupt mask register */

    uint8_t isr; /* interrupt service register */

    uint8_t priority_add; /* highest irq priority */

    uint8_t irq_base;

    uint8_t read_reg_select;

    uint8_t poll;

    uint8_t special_mask;

    uint8_t init_state;

    uint8_t auto_eoi;

    uint8_t rotate_on_auto_eoi;

    uint8_t special_fully_nested_mode;

    uint8_t init4; /* true if 4 byte init */

} PicState;

/* 0 is master pic, 1 is slave pic */

static PicState pics[2];

static int pic_irq_requested;

/* set irq level. If an edge is detected, then the IRR is set to 1 */

static inline void pic_set_irq1(PicState *s, int irq, int level)

{

    int mask;

    mask = 1 << irq;

    if (level) {

        if ((s->last_irr & mask) == 0)

            s->irr |= mask;

        s->last_irr |= mask;

    } else {

        s->last_irr &= ~mask;

    }

}

/* return the highest priority found in mask (highest = smallest

   number). Return 8 if no irq */

static inline int get_priority(PicState *s, int mask)

{

    int priority;

    if (mask == 0)

        return 8;

    priority = 0;

    while ((mask & (1 << ((priority + s->priority_add) & 7))) == 0)

        priority++;

    return priority;

}

/* return the pic wanted interrupt. return -1 if none */

static int pic_get_irq(PicState *s)

{

    int mask, cur_priority, priority;

    mask = s->irr & ~s->imr;

    priority = get_priority(s, mask);

    if (priority == 8)

        return -1;

    /* compute current priority. If special fully nested mode on the

       master, the IRQ coming from the slave is not taken into account

       for the priority computation. */

    mask = s->isr;

    if (s->special_fully_nested_mode && s == &pics[0])

        mask &= ~(1 << 2);

    cur_priority = get_priority(s, mask);

    if (priority < cur_priority) {

        /* higher priority found: an irq should be generated */

        return (priority + s->priority_add) & 7;

    } else {

        return -1;

    }

}

/* raise irq to CPU if necessary. must be called every time the active

   irq may change */

static void pic_update_irq(void)

{

    int irq2, irq;

    /* first look at slave pic */

    irq2 = pic_get_irq(&pics[1]);

    if (irq2 >= 0) {

        /* if irq request by slave pic, signal master PIC */

        pic_set_irq1(&pics[0], 2, 1);

        pic_set_irq1(&pics[0], 2, 0);

    }

    /* look at requested irq */

    irq = pic_get_irq(&pics[0]);

    if (irq >= 0) {

        if (irq == 2) {

            /* from slave pic */

            pic_irq_requested = 8 + irq2;

        } else {

            /* from master pic */

            pic_irq_requested = irq;

        }

#if defined(DEBUG_PIC)

        {

            int i;

            for(i = 0; i < 2; i++) {

                printf("pic%d: imr=%x irr=%x padd=%d\n", 

                       i, pics[i].imr, pics[i].irr, pics[i].priority_add);

            }

        }

        printf("pic: cpu_interrupt req=%d\n", pic_irq_requested);

#endif

        cpu_interrupt(cpu_single_env, CPU_INTERRUPT_HARD);

    }

}

#ifdef DEBUG_IRQ_LATENCY

int64_t irq_time[16];

#endif

#if defined(DEBUG_PIC)

int irq_level[16];

#endif

void pic_set_irq(int irq, int level)

{

#if defined(DEBUG_PIC)

    if (level != irq_level[irq]) {

        printf("pic_set_irq: irq=%d level=%d\n", irq, level);

        irq_level[irq] = level;

    }

#endif

#ifdef DEBUG_IRQ_LATENCY

    if (level) {

        irq_time[irq] = cpu_get_ticks();

    }

#endif

    pic_set_irq1(&pics[irq >> 3], irq & 7, level);

    pic_update_irq();

}

/* acknowledge interrupt 'irq' */

static inline void pic_intack(PicState *s, int irq)

{

    if (s->auto_eoi) {

        if (s->rotate_on_auto_eoi)

            s->priority_add = (irq + 1) & 7;

    } else {

        s->isr |= (1 << irq);

    }

    s->irr &= ~(1 << irq);

}

int cpu_get_pic_interrupt(CPUState *env)

{

    int irq, irq2, intno;

    /* signal the pic that the irq was acked by the CPU */

    irq = pic_irq_requested;

#ifdef DEBUG_IRQ_LATENCY

    printf("IRQ%d latency=%0.3fus\n", 

           irq, 

           (double)(cpu_get_ticks() - irq_time[irq]) * 1000000.0 / ticks_per_sec);

#endif

#if defined(DEBUG_PIC)

    printf("pic_interrupt: irq=%d\n", irq);

#endif

    if (irq >= 8) {

        irq2 = irq & 7;

        pic_intack(&pics[1], irq2);

        irq = 2;

        intno = pics[1].irq_base + irq2;

    } else {

        intno = pics[0].irq_base + irq;

    }

    pic_intack(&pics[0], irq);

    pic_update_irq();

    return intno;

}

static void pic_ioport_write(void *opaque, uint32_t addr, uint32_t val)

{

    PicState *s = opaque;

    int priority, cmd, irq;

#ifdef DEBUG_PIC

    printf("pic_write: addr=0x%02x val=0x%02x\n", addr, val);

#endif

    addr &= 1;

    if (addr == 0) {

        if (val & 0x10) {

            /* init */

            memset(s, 0, sizeof(PicState));

            s->init_state = 1;

            s->init4 = val & 1;

            if (val & 0x02)

                hw_error("single mode not supported");

            if (val & 0x08)

                hw_error("level sensitive irq not supported");

        } else if (val & 0x08) {

            if (val & 0x04)

                s->poll = 1;

            if (val & 0x02)

                s->read_reg_select = val & 1;

            if (val & 0x40)

                s->special_mask = (val >> 5) & 1;

        } else {

            cmd = val >> 5;

            switch(cmd) {

            case 0:

            case 4:

                s->rotate_on_auto_eoi = cmd >> 2;

                break;

            case 1: /* end of interrupt */

            case 5:

                priority = get_priority(s, s->isr);

                if (priority != 8) {

                    irq = (priority + s->priority_add) & 7;

                    s->isr &= ~(1 << irq);

                    if (cmd == 5)

                        s->priority_add = (irq + 1) & 7;

                    pic_update_irq();

                }

                break;

            case 3:

                irq = val & 7;

                s->isr &= ~(1 << irq);

                pic_update_irq();

                break;

            case 6:

                s->priority_add = (val + 1) & 7;

                pic_update_irq();

                break;

            case 7:

                irq = val & 7;

                s->isr &= ~(1 << irq);

                s->priority_add = (irq + 1) & 7;

                pic_update_irq();

                break;

            default:

                /* no operation */

                break;

            }

        }

    } else {

        switch(s->init_state) {

        case 0:

            /* normal mode */

            s->imr = val;

            pic_update_irq();

            break;

        case 1:

            s->irq_base = val & 0xf8;

            s->init_state = 2;

            break;

        case 2:

            if (s->init4) {

                s->init_state = 3;

            } else {

                s->init_state = 0;

            }

            break;

        case 3:

            s->special_fully_nested_mode = (val >> 4) & 1;

            s->auto_eoi = (val >> 1) & 1;

            s->init_state = 0;

            break;

        }

    }

}

static uint32_t pic_poll_read (PicState *s, uint32_t addr1)

{

    int ret;

    ret = pic_get_irq(s);

    if (ret >= 0) {

        if (addr1 >> 7) {

            pics[0].isr &= ~(1 << 2);

            pics[0].irr &= ~(1 << 2);

        }

        s->irr &= ~(1 << ret);

        s->isr &= ~(1 << ret);

        if (addr1 >> 7 || ret != 2)

            pic_update_irq();

    } else {

        ret = 0x07;

        pic_update_irq();

    }

    return ret;

}

static uint32_t pic_ioport_read(void *opaque, uint32_t addr1)

{

    PicState *s = opaque;

    unsigned int addr;

    int ret;

    addr = addr1;

    addr &= 1;

    if (s->poll) {

        ret = pic_poll_read(s, addr1);

        s->poll = 0;

    } else {

        if (addr == 0) {

            if (s->read_reg_select)

                ret = s->isr;

            else

                ret = s->irr;

        } else {

            ret = s->imr;

        }

    }

#ifdef DEBUG_PIC

    printf("pic_read: addr=0x%02x val=0x%02x\n", addr1, ret);

#endif

    return ret;

}

/* memory mapped interrupt status */

uint32_t pic_intack_read(CPUState *env)

{

    int ret;

    ret = pic_poll_read(&pics[0], 0x00);

    if (ret == 2)

        ret = pic_poll_read(&pics[1], 0x80) + 8;

    /* Prepare for ISR read */

    pics[0].read_reg_select = 1;

    return ret;

}

static void pic_save(QEMUFile *f, void *opaque)

{

    PicState *s = opaque;

    qemu_put_8s(f, &s->last_irr);

    qemu_put_8s(f, &s->irr);

    qemu_put_8s(f, &s->imr);

    qemu_put_8s(f, &s->isr);

    qemu_put_8s(f, &s->priority_add);

    qemu_put_8s(f, &s->irq_base);

    qemu_put_8s(f, &s->read_reg_select);

    qemu_put_8s(f, &s->poll);

    qemu_put_8s(f, &s->special_mask);

    qemu_put_8s(f, &s->init_state);

    qemu_put_8s(f, &s->auto_eoi);

    qemu_put_8s(f, &s->rotate_on_auto_eoi);

    qemu_put_8s(f, &s->special_fully_nested_mode);

    qemu_put_8s(f, &s->init4);

}

static int pic_load(QEMUFile *f, void *opaque, int version_id)

{

    PicState *s = opaque;

    if (version_id != 1)

        return -EINVAL;

    qemu_get_8s(f, &s->last_irr);

    qemu_get_8s(f, &s->irr);

    qemu_get_8s(f, &s->imr);

    qemu_get_8s(f, &s->isr);

    qemu_get_8s(f, &s->priority_add);

    qemu_get_8s(f, &s->irq_base);

    qemu_get_8s(f, &s->read_reg_select);

    qemu_get_8s(f, &s->poll);

    qemu_get_8s(f, &s->special_mask);

    qemu_get_8s(f, &s->init_state);

    qemu_get_8s(f, &s->auto_eoi);

    qemu_get_8s(f, &s->rotate_on_auto_eoi);

    qemu_get_8s(f, &s->special_fully_nested_mode);

    qemu_get_8s(f, &s->init4);

    return 0;

}

/* XXX: add generic master/slave system */

static void pic_init1(int io_addr, PicState *s)

{

    register_ioport_write(io_addr, 2, 1, pic_ioport_write, s);

    register_ioport_read(io_addr, 2, 1, pic_ioport_read, s);

    register_savevm("i8259", io_addr, 1, pic_save, pic_load, s);

}

void pic_info(void)

{

    int i;

    PicState *s;

    for(i=0;i<2;i++) {

        s = &pics[i];

        term_printf("pic%d: irr=%02x imr=%02x isr=%02x hprio=%d irq_base=%02x rr_sel=%d\n",

                    i, s->irr, s->imr, s->isr, s->priority_add, s->irq_base, s->read_reg_select);

    }

}

void pic_init(void)

{

    pic_init1(0x20, &pics[0]);

    pic_init1(0xa0, &pics[1]);

}