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/*

 * QEMU Sparc SLAVIO timer controller emulation

 *

 * Copyright (c) 2003-2005 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"

//#define DEBUG_TIMER

#ifdef DEBUG_TIMER

#define DPRINTF(fmt, args...) \

do { printf("TIMER: " fmt , ##args); } while (0)

#else

#define DPRINTF(fmt, args...)

#endif

/*

 * Registers of hardware timer in sun4m.

 *

 * This is the timer/counter part of chip STP2001 (Slave I/O), also

 * produced as NCR89C105. See

 * http://www.ibiblio.org/pub/historic-linux/early-ports/Sparc/NCR/NCR89C105.txt

 * 

 * The 31-bit counter is incremented every 500ns by bit 9. Bits 8..0

 * are zero. Bit 31 is 1 when count has been reached.

 *

 * Per-CPU timers interrupt local CPU, system timer uses normal

 * interrupt routing.

 *

 */

typedef struct SLAVIO_TIMERState {

    uint32_t limit, count, counthigh;

    int64_t count_load_time;

    int64_t expire_time;

    int64_t stop_time, tick_offset;

    QEMUTimer *irq_timer;

    int irq;

    int reached, stopped;

    int mode; // 0 = processor, 1 = user, 2 = system

    unsigned int cpu;

} SLAVIO_TIMERState;

#define TIMER_MAXADDR 0x1f

#define CNT_FREQ 2000000

// Update count, set irq, update expire_time

static void slavio_timer_get_out(SLAVIO_TIMERState *s)

{

    int out;

    int64_t diff, ticks, count;

    uint32_t limit;

    // There are three clock tick units: CPU ticks, register units

    // (nanoseconds), and counter ticks (500 ns).

    if (s->mode == 1 && s->stopped)

        ticks = s->stop_time;

    else

        ticks = qemu_get_clock(vm_clock) - s->tick_offset;

    out = (ticks > s->expire_time);

    if (out)

        s->reached = 0x80000000;

    if (!s->limit)

        limit = 0x7fffffff;

    else

        limit = s->limit;

    // Convert register units to counter ticks

    limit = limit >> 9;

    // Convert cpu ticks to counter ticks

    diff = muldiv64(ticks - s->count_load_time, CNT_FREQ, ticks_per_sec);

    // Calculate what the counter should be, convert to register

    // units

    count = diff % limit;

    s->count = count << 9;

    s->counthigh = count >> 22;

    // Expire time: CPU ticks left to next interrupt

    // Convert remaining counter ticks to CPU ticks

    s->expire_time = ticks + muldiv64(limit - count, ticks_per_sec, CNT_FREQ);

    DPRINTF("irq %d limit %d reached %d d %lld count %d s->c %x diff %lld stopped %d mode %d\n", s->irq, limit, s->reached?1:0, (ticks-s->count_load_time), count, s->count, s->expire_time - ticks, s->stopped, s->mode);

    if (s->mode != 1)

        pic_set_irq_cpu(s->irq, out, s->cpu);

}

// timer callback

static void slavio_timer_irq(void *opaque)

{

    SLAVIO_TIMERState *s = opaque;

    if (!s->irq_timer)

        return;

    slavio_timer_get_out(s);

    if (s->mode != 1)

        qemu_mod_timer(s->irq_timer, s->expire_time);

}

static uint32_t slavio_timer_mem_readl(void *opaque, target_phys_addr_t addr)

{

    SLAVIO_TIMERState *s = opaque;

    uint32_t saddr;

    saddr = (addr & TIMER_MAXADDR) >> 2;

    switch (saddr) {

    case 0:

        // read limit (system counter mode) or read most signifying

        // part of counter (user mode)

        if (s->mode != 1) {

            // clear irq

            pic_set_irq_cpu(s->irq, 0, s->cpu);

            s->count_load_time = qemu_get_clock(vm_clock);

            s->reached = 0;

            return s->limit;

        }

        else {

            slavio_timer_get_out(s);

            return s->counthigh & 0x7fffffff;

        }

    case 1:

        // read counter and reached bit (system mode) or read lsbits

        // of counter (user mode)

        slavio_timer_get_out(s);

        if (s->mode != 1)

            return (s->count & 0x7fffffff) | s->reached;

        else

            return s->count;

    case 3:

        // read start/stop status

        return s->stopped;

    case 4:

        // read user/system mode

        return s->mode & 1;

    default:

        return 0;

    }

}

static void slavio_timer_mem_writel(void *opaque, target_phys_addr_t addr, uint32_t val)

{

    SLAVIO_TIMERState *s = opaque;

    uint32_t saddr;

    saddr = (addr & TIMER_MAXADDR) >> 2;

    switch (saddr) {

    case 0:

        // set limit, reset counter

        s->count_load_time = qemu_get_clock(vm_clock);

        // fall through

    case 2:

        // set limit without resetting counter

        if (!val)

            s->limit = 0x7fffffff;

        else

            s->limit = val & 0x7fffffff;

        slavio_timer_irq(s);

        break;

    case 3:

        // start/stop user counter

        if (s->mode == 1) {

            if (val & 1) {

                s->stop_time = qemu_get_clock(vm_clock);

                s->stopped = 1;

            }

            else {

                if (s->stopped)

                    s->tick_offset += qemu_get_clock(vm_clock) - s->stop_time;

                s->stopped = 0;

            }

        }

        break;

    case 4:

        // bit 0: user (1) or system (0) counter mode

        if (s->mode == 0 || s->mode == 1)

            s->mode = val & 1;

        break;

    default:

        break;

    }

}

static CPUReadMemoryFunc *slavio_timer_mem_read[3] = {

    slavio_timer_mem_readl,

    slavio_timer_mem_readl,

    slavio_timer_mem_readl,

};

static CPUWriteMemoryFunc *slavio_timer_mem_write[3] = {

    slavio_timer_mem_writel,

    slavio_timer_mem_writel,

    slavio_timer_mem_writel,

};

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

{

    SLAVIO_TIMERState *s = opaque;

    qemu_put_be32s(f, &s->limit);

    qemu_put_be32s(f, &s->count);

    qemu_put_be32s(f, &s->counthigh);

    qemu_put_be64s(f, &s->count_load_time);

    qemu_put_be64s(f, &s->expire_time);

    qemu_put_be64s(f, &s->stop_time);

    qemu_put_be64s(f, &s->tick_offset);

    qemu_put_be32s(f, &s->irq);

    qemu_put_be32s(f, &s->reached);

    qemu_put_be32s(f, &s->stopped);

    qemu_put_be32s(f, &s->mode);

}

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

{

    SLAVIO_TIMERState *s = opaque;

    if (version_id != 1)

        return -EINVAL;

    qemu_get_be32s(f, &s->limit);

    qemu_get_be32s(f, &s->count);

    qemu_get_be32s(f, &s->counthigh);

    qemu_get_be64s(f, &s->count_load_time);

    qemu_get_be64s(f, &s->expire_time);

    qemu_get_be64s(f, &s->stop_time);

    qemu_get_be64s(f, &s->tick_offset);

    qemu_get_be32s(f, &s->irq);

    qemu_get_be32s(f, &s->reached);

    qemu_get_be32s(f, &s->stopped);

    qemu_get_be32s(f, &s->mode);

    return 0;

}

static void slavio_timer_reset(void *opaque)

{

    SLAVIO_TIMERState *s = opaque;

    s->limit = 0;

    s->count = 0;

    s->count_load_time = qemu_get_clock(vm_clock);;

    s->stop_time = s->count_load_time;

    s->tick_offset = 0;

    s->reached = 0;

    s->mode &= 2;

    s->stopped = 1;

    slavio_timer_get_out(s);

}

void slavio_timer_init(uint32_t addr, int irq, int mode, unsigned int cpu)

{

    int slavio_timer_io_memory;

    SLAVIO_TIMERState *s;

    s = qemu_mallocz(sizeof(SLAVIO_TIMERState));

    if (!s)

        return;

    s->irq = irq;

    s->mode = mode;

    s->cpu = cpu;

    s->irq_timer = qemu_new_timer(vm_clock, slavio_timer_irq, s);

    slavio_timer_io_memory = cpu_register_io_memory(0, slavio_timer_mem_read,

                                                    slavio_timer_mem_write, s);

    cpu_register_physical_memory(addr, TIMER_MAXADDR, slavio_timer_io_memory);

    register_savevm("slavio_timer", addr, 1, slavio_timer_save, slavio_timer_load, s);

    qemu_register_reset(slavio_timer_reset, s);

    slavio_timer_reset(s);

}