Archipelago » qemu

/*

 * QEMU OpenRISC timer support

 *

 * Copyright (c) 2011-2012 Jia Liu <proljc@gmail.com>

 *                         Zhizhou Zhang <etouzh@gmail.com>

 *

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

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, see <http://www.gnu.org/licenses/>.

 */

#include "cpu.h"

#include "hw.h"

#include "qemu-timer.h"

#define TIMER_FREQ    (20 * 1000 * 1000)    /* 20MHz */

/* The time when TTCR changes */

static uint64_t last_clk;

static int is_counting;

void cpu_openrisc_count_update(OpenRISCCPU *cpu)

{

    uint64_t now, next;

    uint32_t wait;

    now = qemu_get_clock_ns(vm_clock);

    if (!is_counting) {

        qemu_del_timer(cpu->env.timer);

        last_clk = now;

        return;

    }

    cpu->env.ttcr += (uint32_t)muldiv64(now - last_clk, TIMER_FREQ,

                                        get_ticks_per_sec());

    last_clk = now;

    if ((cpu->env.ttmr & TTMR_TP) <= (cpu->env.ttcr & TTMR_TP)) {

        wait = TTMR_TP - (cpu->env.ttcr & TTMR_TP) + 1;

        wait += cpu->env.ttmr & TTMR_TP;

    } else {

        wait = (cpu->env.ttmr & TTMR_TP) - (cpu->env.ttcr & TTMR_TP);

    }

    next = now + muldiv64(wait, get_ticks_per_sec(), TIMER_FREQ);

    qemu_mod_timer(cpu->env.timer, next);

}

void cpu_openrisc_count_start(OpenRISCCPU *cpu)

{

    is_counting = 1;

    cpu_openrisc_count_update(cpu);

}

void cpu_openrisc_count_stop(OpenRISCCPU *cpu)

{

    is_counting = 0;

    cpu_openrisc_count_update(cpu);

}

static void openrisc_timer_cb(void *opaque)

{

    OpenRISCCPU *cpu = opaque;

    if ((cpu->env.ttmr & TTMR_IE) &&

         qemu_timer_expired(cpu->env.timer, qemu_get_clock_ns(vm_clock))) {

        cpu->env.ttmr |= TTMR_IP;

        cpu->env.interrupt_request |= CPU_INTERRUPT_TIMER;

    }

    switch (cpu->env.ttmr & TTMR_M) {

    case TIMER_NONE:

        break;

    case TIMER_INTR:

        cpu->env.ttcr = 0;

        cpu_openrisc_count_start(cpu);

        break;

    case TIMER_SHOT:

        cpu_openrisc_count_stop(cpu);

        break;

    case TIMER_CONT:

        cpu_openrisc_count_start(cpu);

        break;

    }

}

void cpu_openrisc_clock_init(OpenRISCCPU *cpu)

{

    cpu->env.timer = qemu_new_timer_ns(vm_clock, &openrisc_timer_cb, cpu);

    cpu->env.ttmr = 0x00000000;

    cpu->env.ttcr = 0x00000000;

}