Archipelago » qemu

/*****************************************************************************/

/* PPC time base and decrementer emulation */

//#define DEBUG_TB

struct ppc_tb_t {

    /* Time base management */

    int64_t  tb_offset;    /* Compensation               */

    uint32_t tb_freq;      /* TB frequency               */

    /* Decrementer management */

    uint64_t decr_next;    /* Tick for next decr interrupt  */

    struct QEMUTimer *decr_timer;

};

static inline uint64_t cpu_ppc_get_tb (ppc_tb_t *tb_env)

{

    /* TB time in tb periods */

    return muldiv64(qemu_get_clock(vm_clock) + tb_env->tb_offset,

		    tb_env->tb_freq, ticks_per_sec);

}

uint32_t cpu_ppc_load_tbl (CPUState *env)

{

    ppc_tb_t *tb_env = env->tb_env;

    uint64_t tb;

    tb = cpu_ppc_get_tb(tb_env);

#ifdef DEBUG_TB

    {

         static int last_time;

	 int now;

	 now = time(NULL);

	 if (last_time != now) {

	     last_time = now;

	     printf("%s: tb=0x%016lx %d %08lx\n",

                    __func__, tb, now, tb_env->tb_offset);

	 }

    }

#endif

    return tb & 0xFFFFFFFF;

}

uint32_t cpu_ppc_load_tbu (CPUState *env)

{

    ppc_tb_t *tb_env = env->tb_env;

    uint64_t tb;

    tb = cpu_ppc_get_tb(tb_env);

#ifdef DEBUG_TB

    printf("%s: tb=0x%016lx\n", __func__, tb);

#endif

    return tb >> 32;

}

static void cpu_ppc_store_tb (ppc_tb_t *tb_env, uint64_t value)

{

    tb_env->tb_offset = muldiv64(value, ticks_per_sec, tb_env->tb_freq)

        - qemu_get_clock(vm_clock);

#ifdef DEBUG_TB

    printf("%s: tb=0x%016lx offset=%08x\n", __func__, value);

#endif

}

void cpu_ppc_store_tbu (CPUState *env, uint32_t value)

{

    ppc_tb_t *tb_env = env->tb_env;

    cpu_ppc_store_tb(tb_env,

                     ((uint64_t)value << 32) | cpu_ppc_load_tbl(env));

}

void cpu_ppc_store_tbl (CPUState *env, uint32_t value)

{

    ppc_tb_t *tb_env = env->tb_env;

    cpu_ppc_store_tb(tb_env,

                     ((uint64_t)cpu_ppc_load_tbu(env) << 32) | value);

}

uint32_t cpu_ppc_load_decr (CPUState *env)

{

    ppc_tb_t *tb_env = env->tb_env;

    uint32_t decr;

    decr = muldiv64(tb_env->decr_next - qemu_get_clock(vm_clock),

                    tb_env->tb_freq, ticks_per_sec);

#ifdef DEBUG_TB

    printf("%s: 0x%08x\n", __func__, decr);

#endif

    return decr;

}

/* When decrementer expires,

 * all we need to do is generate or queue a CPU exception

 */

static inline void cpu_ppc_decr_excp (CPUState *env)

{

    /* Raise it */

#ifdef DEBUG_TB

    printf("raise decrementer exception\n");

#endif

    cpu_interrupt(env, CPU_INTERRUPT_TIMER);

}

static void _cpu_ppc_store_decr (CPUState *env, uint32_t decr,

                                 uint32_t value, int is_excp)

{

    ppc_tb_t *tb_env = env->tb_env;

    uint64_t now, next;

#ifdef DEBUG_TB

    printf("%s: 0x%08x => 0x%08x\n", __func__, decr, value);

#endif

    now = qemu_get_clock(vm_clock);

    next = now + muldiv64(value, ticks_per_sec, tb_env->tb_freq);

    if (is_excp)

        next += tb_env->decr_next - now;

    if (next == now)

	next++;

    tb_env->decr_next = next;

    /* Adjust timer */

    qemu_mod_timer(tb_env->decr_timer, next);

    /* If we set a negative value and the decrementer was positive,

     * raise an exception.

     */

    if ((value & 0x80000000) && !(decr & 0x80000000))

	cpu_ppc_decr_excp(env);

}

void cpu_ppc_store_decr (CPUState *env, uint32_t value)

{

    _cpu_ppc_store_decr(env, cpu_ppc_load_decr(env), value, 0);

}

static void cpu_ppc_decr_cb (void *opaque)

{

    _cpu_ppc_store_decr(opaque, 0x00000000, 0xFFFFFFFF, 1);

}

/* Set up (once) timebase frequency (in Hz) */

ppc_tb_t *cpu_ppc_tb_init (CPUState *env, uint32_t freq)

{

    ppc_tb_t *tb_env;

    tb_env = qemu_mallocz(sizeof(ppc_tb_t));

    if (tb_env == NULL)

        return NULL;

    env->tb_env = tb_env;

    if (tb_env->tb_freq == 0 || 1) {

	tb_env->tb_freq = freq;

	/* Create new timer */

	tb_env->decr_timer =

            qemu_new_timer(vm_clock, &cpu_ppc_decr_cb, env);

	/* There is a bug in  2.4 kernels:

	 * if a decrementer exception is pending when it enables msr_ee,

	 * it's not ready to handle it...

	 */

	_cpu_ppc_store_decr(env, 0xFFFFFFFF, 0xFFFFFFFF, 0);

    }

    return tb_env;

}

#if 0

/*****************************************************************************/

/* Handle system reset (for now, just stop emulation) */

void cpu_ppc_reset (CPUState *env)

{

    printf("Reset asked... Stop emulation\n");

    abort();

}

#endif

/*****************************************************************************/