/*

 * ARM AMBA PrimeCell PL031 RTC

 *

 * Copyright (c) 2007 CodeSourcery

 *

 * This file is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 */

#include "hw.h"

#include "primecell.h"

#include "qemu-timer.h"

#include "sysemu.h"

//#define DEBUG_PL031

#ifdef DEBUG_PL031

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

do { printf("pl031: " fmt , ##args); } while (0)

#else

#define DPRINTF(fmt, args...) do {} while(0)

#endif

#define RTC_DR      0x00    /* Data read register */

#define RTC_MR      0x04    /* Match register */

#define RTC_LR      0x08    /* Data load register */

#define RTC_CR      0x0c    /* Control register */

#define RTC_IMSC    0x10    /* Interrupt mask and set register */

#define RTC_RIS     0x14    /* Raw interrupt status register */

#define RTC_MIS     0x18    /* Masked interrupt status register */

#define RTC_ICR     0x1c    /* Interrupt clear register */

typedef struct {

    QEMUTimer *timer;

    qemu_irq irq;

    uint64_t start_time;

    uint32_t tick_offset;

    uint32_t mr;

    uint32_t lr;

    uint32_t cr;

    uint32_t im;

    uint32_t is;

} pl031_state;

static const unsigned char pl031_id[] = {

    0x31, 0x10, 0x14, 0x00,         /* Device ID        */

    0x0d, 0xf0, 0x05, 0xb1          /* Cell ID      */

};

static void pl031_update(pl031_state *s)

{

    qemu_set_irq(s->irq, s->is & s->im);

}

static void pl031_interrupt(void * opaque)

{

    pl031_state *s = (pl031_state *)opaque;

    s->im = 1;

    DPRINTF("Alarm raised\n");

    pl031_update(s);

}

static uint32_t pl031_get_count(pl031_state *s)

{

    /* This assumes qemu_get_clock returns the time since the machine was

       created.  */

    return s->tick_offset + qemu_get_clock(vm_clock) / ticks_per_sec;

}

static void pl031_set_alarm(pl031_state *s)

{

    int64_t now;

    uint32_t ticks;

    now = qemu_get_clock(vm_clock);

    ticks = s->tick_offset + now / ticks_per_sec;

    /* The timer wraps around.  This subtraction also wraps in the same way,

       and gives correct results when alarm < now_ticks.  */

    ticks = s->mr - ticks;

    DPRINTF("Alarm set in %ud ticks\n", ticks);

    if (ticks == 0) {

        qemu_del_timer(s->timer);

        pl031_interrupt(s);

    } else {

        qemu_mod_timer(s->timer, now + (int64_t)ticks * ticks_per_sec);

    }

}

static uint32_t pl031_read(void *opaque, target_phys_addr_t offset)

{

    pl031_state *s = (pl031_state *)opaque;

    if (offset >= 0xfe0  &&  offset < 0x1000)

        return pl031_id[(offset - 0xfe0) >> 2];

    switch (offset) {

    case RTC_DR:

        return pl031_get_count(s);

    case RTC_MR:

        return s->mr;

    case RTC_IMSC:

        return s->im;

    case RTC_RIS:

        return s->is;

    case RTC_LR:

        return s->lr;

    case RTC_CR:

        /* RTC is permanently enabled.  */

        return 1;

    case RTC_MIS:

        return s->is & s->im;

    case RTC_ICR:

        fprintf(stderr, "qemu: pl031_read: Unexpected offset 0x%x\n",

                (int)offset);

        break;

    default:

        cpu_abort(cpu_single_env, "pl031_read: Bad offset 0x%x\n",

                  (int)offset);

        break;

    }

    return 0;

}

static void pl031_write(void * opaque, target_phys_addr_t offset,

                        uint32_t value)

{

    pl031_state *s = (pl031_state *)opaque;

    switch (offset) {

    case RTC_LR:

        s->tick_offset += value - pl031_get_count(s);

        pl031_set_alarm(s);

        break;

    case RTC_MR:

        s->mr = value;

        pl031_set_alarm(s);

        break;

    case RTC_IMSC:

        s->im = value & 1;

        DPRINTF("Interrupt mask %d\n", s->im);

        pl031_update(s);

        break;

    case RTC_ICR:

        /* The PL031 documentation (DDI0224B) states that the interupt is

           cleared when bit 0 of the written value is set.  However the

           arm926e documentation (DDI0287B) states that the interrupt is

           cleared when any value is written.  */

        DPRINTF("Interrupt cleared");

        s->is = 0;

        pl031_update(s);

        break;

    case RTC_CR:

        /* Written value is ignored.  */

        break;

    case RTC_DR:

    case RTC_MIS:

    case RTC_RIS:

        fprintf(stderr, "qemu: pl031_write: Unexpected offset 0x%x\n",

                (int)offset);

        break;

    default:

        cpu_abort(cpu_single_env, "pl031_write: Bad offset 0x%x\n",

                  (int)offset);

        break;

    }

}

static CPUWriteMemoryFunc * pl031_writefn[] = {

    pl031_write,

    pl031_write,

    pl031_write

};

static CPUReadMemoryFunc * pl031_readfn[] = {

    pl031_read,

    pl031_read,

    pl031_read

};

void pl031_init(uint32_t base, qemu_irq irq)

{

    int iomemtype;

    pl031_state *s;

    struct tm tm;

    s = qemu_mallocz(sizeof(pl031_state));

    if (!s)

        cpu_abort(cpu_single_env, "pl031_init: Out of memory\n");

    iomemtype = cpu_register_io_memory(0, pl031_readfn, pl031_writefn, s);

    if (iomemtype == -1)

        cpu_abort(cpu_single_env, "pl031_init: Can't register I/O memory\n");

    cpu_register_physical_memory(base, 0x00001000, iomemtype);

    s->irq  = irq;

    /* ??? We assume vm_clock is zero at this point.  */

    qemu_get_timedate(&tm, 0);

    s->tick_offset = mktimegm(&tm);

    s->timer = qemu_new_timer(vm_clock, pl031_interrupt, s);

}