Archipelago » qemu

/* 

 * ARM PrimeCell Timer modules.

 *

 * Copyright (c) 2005-2006 CodeSourcery.

 * Written by Paul Brook

 *

 * This code is licenced under the GPL.

 */

#include "vl.h"

#include "arm_pic.h"

/* Common timer implementation.  */

#define TIMER_CTRL_ONESHOT      (1 << 0)

#define TIMER_CTRL_32BIT        (1 << 1)

#define TIMER_CTRL_DIV1         (0 << 2)

#define TIMER_CTRL_DIV16        (1 << 2)

#define TIMER_CTRL_DIV256       (2 << 2)

#define TIMER_CTRL_IE           (1 << 5)

#define TIMER_CTRL_PERIODIC     (1 << 6)

#define TIMER_CTRL_ENABLE       (1 << 7)

typedef struct {

    int64_t next_time;

    int64_t expires;

    int64_t loaded;

    QEMUTimer *timer;

    uint32_t control;

    uint32_t count;

    uint32_t limit;

    int raw_freq;

    int freq;

    int int_level;

    qemu_irq irq;

} arm_timer_state;

/* Calculate the new expiry time of the given timer.  */

static void arm_timer_reload(arm_timer_state *s)

{

    int64_t delay;

    s->loaded = s->expires;

    delay = muldiv64(s->count, ticks_per_sec, s->freq);

    if (delay == 0)

        delay = 1;

    s->expires += delay;

}

/* Check all active timers, and schedule the next timer interrupt.  */

static void arm_timer_update(arm_timer_state *s, int64_t now)

{

    int64_t next;

    /* Ignore disabled timers.  */

    if ((s->control & TIMER_CTRL_ENABLE) == 0)

        return;

    /* Ignore expired one-shot timers.  */

    if (s->count == 0 && (s->control & TIMER_CTRL_ONESHOT))

        return;

    if (s->expires - now <= 0) {

        /* Timer has expired.  */

        s->int_level = 1;

        if (s->control & TIMER_CTRL_ONESHOT) {

            /* One-shot.  */

            s->count = 0;

        } else {

            if ((s->control & TIMER_CTRL_PERIODIC) == 0) {

                /* Free running.  */

                if (s->control & TIMER_CTRL_32BIT)

                    s->count = 0xffffffff;

                else

                    s->count = 0xffff;

            } else {

                  /* Periodic.  */

                  s->count = s->limit;

            }

        }

    }

    while (s->expires - now <= 0) {

        arm_timer_reload(s);

    }

    /* Update interrupts.  */

    if (s->int_level && (s->control & TIMER_CTRL_IE)) {

        qemu_irq_raise(s->irq);

    } else {

        qemu_irq_lower(s->irq);

    }

    next = now;

    if (next - s->expires < 0)

        next = s->expires;

    /* Schedule the next timer interrupt.  */

    if (next == now) {

        qemu_del_timer(s->timer);

        s->next_time = 0;

    } else if (next != s->next_time) {

        qemu_mod_timer(s->timer, next);

        s->next_time = next;

    }

}

/* Return the current value of the timer.  */

static uint32_t arm_timer_getcount(arm_timer_state *s, int64_t now)

{

    int64_t left;

    int64_t period;

    if (s->count == 0)

        return 0;

    if ((s->control & TIMER_CTRL_ENABLE) == 0)

        return s->count;

    left = s->expires - now;

    period = s->expires - s->loaded;

    /* If the timer should have expired then return 0.  This can happen

       when the host timer signal doesnt occur immediately.  It's better to

       have a timer appear to sit at zero for a while than have it wrap

       around before the guest interrupt is raised.  */

    /* ??? Could we trigger the interrupt here?  */

    if (left < 0)

        return 0;

    /* We need to calculate count * elapsed / period without overfowing.

       Scale both elapsed and period so they fit in a 32-bit int.  */

    while (period != (int32_t)period) {

        period >>= 1;

        left >>= 1;

    }

    return ((uint64_t)s->count * (uint64_t)(int32_t)left)

            / (int32_t)period;

}

uint32_t arm_timer_read(void *opaque, target_phys_addr_t offset)

{

    arm_timer_state *s = (arm_timer_state *)opaque;

    switch (offset >> 2) {

    case 0: /* TimerLoad */

    case 6: /* TimerBGLoad */

        return s->limit;

    case 1: /* TimerValue */

        return arm_timer_getcount(s, qemu_get_clock(vm_clock));

    case 2: /* TimerControl */

        return s->control;

    case 4: /* TimerRIS */

        return s->int_level;

    case 5: /* TimerMIS */

        if ((s->control & TIMER_CTRL_IE) == 0)

            return 0;

        return s->int_level;

    default:

        cpu_abort (cpu_single_env, "arm_timer_read: Bad offset %x\n", offset);

        return 0;

    }

}

static void arm_timer_write(void *opaque, target_phys_addr_t offset,

                            uint32_t value)

{

    arm_timer_state *s = (arm_timer_state *)opaque;

    int64_t now;

    now = qemu_get_clock(vm_clock);

    switch (offset >> 2) {

    case 0: /* TimerLoad */

        s->limit = value;

        s->count = value;

        s->expires = now;

        arm_timer_reload(s);

        break;

    case 1: /* TimerValue */

        /* ??? Linux seems to want to write to this readonly register.

           Ignore it.  */

        break;

    case 2: /* TimerControl */

        if (s->control & TIMER_CTRL_ENABLE) {

            /* Pause the timer if it is running.  This may cause some

               inaccuracy dure to rounding, but avoids a whole lot of other

               messyness.  */

            s->count = arm_timer_getcount(s, now);

        }

        s->control = value;

        s->freq = s->raw_freq;

        /* ??? Need to recalculate expiry time after changing divisor.  */

        switch ((value >> 2) & 3) {

        case 1: s->freq >>= 4; break;

        case 2: s->freq >>= 8; break;

        }

        if (s->control & TIMER_CTRL_ENABLE) {

            /* Restart the timer if still enabled.  */

            s->expires = now;

            arm_timer_reload(s);

        }

        break;

    case 3: /* TimerIntClr */

        s->int_level = 0;

        break;

    case 6: /* TimerBGLoad */

        s->limit = value;

        break;

    default:

        cpu_abort (cpu_single_env, "arm_timer_write: Bad offset %x\n", offset);

    }

    arm_timer_update(s, now);

}

static void arm_timer_tick(void *opaque)

{

    int64_t now;

    now = qemu_get_clock(vm_clock);

    arm_timer_update((arm_timer_state *)opaque, now);

}

static void *arm_timer_init(uint32_t freq, qemu_irq irq)

{

    arm_timer_state *s;

    s = (arm_timer_state *)qemu_mallocz(sizeof(arm_timer_state));

    s->irq = irq;

    s->raw_freq = s->freq = 1000000;

    s->control = TIMER_CTRL_IE;

    s->count = 0xffffffff;

    s->timer = qemu_new_timer(vm_clock, arm_timer_tick, s);

    /* ??? Save/restore.  */

    return s;

}

/* ARM PrimeCell SP804 dual timer module.

   Docs for this device don't seem to be publicly available.  This

   implementation is based on guesswork, the linux kernel sources and the

   Integrator/CP timer modules.  */

typedef struct {

    void *timer[2];

    int level[2];

    uint32_t base;

    qemu_irq irq;

} sp804_state;

/* Merge the IRQs from the two component devices.  */

static void sp804_set_irq(void *opaque, int irq, int level)

{

    sp804_state *s = (sp804_state *)opaque;

    s->level[irq] = level;

    qemu_set_irq(s->irq, s->level[0] || s->level[1]);

}

static uint32_t sp804_read(void *opaque, target_phys_addr_t offset)

{

    sp804_state *s = (sp804_state *)opaque;

    /* ??? Don't know the PrimeCell ID for this device.  */

    offset -= s->base;

    if (offset < 0x20) {

        return arm_timer_read(s->timer[0], offset);

    } else {

        return arm_timer_read(s->timer[1], offset - 0x20);

    }

}

static void sp804_write(void *opaque, target_phys_addr_t offset,

                        uint32_t value)

{

    sp804_state *s = (sp804_state *)opaque;

    offset -= s->base;

    if (offset < 0x20) {

        arm_timer_write(s->timer[0], offset, value);

    } else {

        arm_timer_write(s->timer[1], offset - 0x20, value);

    }

}

static CPUReadMemoryFunc *sp804_readfn[] = {

   sp804_read,

   sp804_read,

   sp804_read

};

static CPUWriteMemoryFunc *sp804_writefn[] = {

   sp804_write,

   sp804_write,

   sp804_write

};

void sp804_init(uint32_t base, qemu_irq irq)

{

    int iomemtype;

    sp804_state *s;

    qemu_irq *qi;

    s = (sp804_state *)qemu_mallocz(sizeof(sp804_state));

    qi = qemu_allocate_irqs(sp804_set_irq, s, 2);

    s->base = base;

    s->irq = irq;

    /* ??? The timers are actually configurable between 32kHz and 1MHz, but

       we don't implement that.  */

    s->timer[0] = arm_timer_init(1000000, qi[0]);

    s->timer[1] = arm_timer_init(1000000, qi[1]);

    iomemtype = cpu_register_io_memory(0, sp804_readfn,

                                       sp804_writefn, s);

    cpu_register_physical_memory(base, 0x00000fff, iomemtype);

    /* ??? Save/restore.  */

}

/* Integrator/CP timer module.  */

typedef struct {

    void *timer[3];

    uint32_t base;

} icp_pit_state;

static uint32_t icp_pit_read(void *opaque, target_phys_addr_t offset)

{

    icp_pit_state *s = (icp_pit_state *)opaque;

    int n;

    /* ??? Don't know the PrimeCell ID for this device.  */

    offset -= s->base;

    n = offset >> 8;

    if (n > 3)

        cpu_abort(cpu_single_env, "sp804_read: Bad timer %d\n", n);

    return arm_timer_read(s->timer[n], offset & 0xff);

}

static void icp_pit_write(void *opaque, target_phys_addr_t offset,

                          uint32_t value)

{

    icp_pit_state *s = (icp_pit_state *)opaque;

    int n;

    offset -= s->base;

    n = offset >> 8;

    if (n > 3)

        cpu_abort(cpu_single_env, "sp804_write: Bad timer %d\n", n);

    arm_timer_write(s->timer[n], offset & 0xff, value);

}

static CPUReadMemoryFunc *icp_pit_readfn[] = {

   icp_pit_read,

   icp_pit_read,

   icp_pit_read

};

static CPUWriteMemoryFunc *icp_pit_writefn[] = {

   icp_pit_write,

   icp_pit_write,

   icp_pit_write

};

void icp_pit_init(uint32_t base, qemu_irq *pic, int irq)

{

    int iomemtype;

    icp_pit_state *s;

    s = (icp_pit_state *)qemu_mallocz(sizeof(icp_pit_state));

    s->base = base;

    /* Timer 0 runs at the system clock speed (40MHz).  */

    s->timer[0] = arm_timer_init(40000000, pic[irq]);

    /* The other two timers run at 1MHz.  */

    s->timer[1] = arm_timer_init(1000000, pic[irq + 1]);

    s->timer[2] = arm_timer_init(1000000, pic[irq + 2]);

    iomemtype = cpu_register_io_memory(0, icp_pit_readfn,

                                       icp_pit_writefn, s);

    cpu_register_physical_memory(base, 0x00000fff, iomemtype);

    /* ??? Save/restore.  */

}