LXR qemu/hw/mips/cputimer.c

   1/*
   2 * QEMU MIPS timer support
   3 *
   4 * Permission is hereby granted, free of charge, to any person obtaining a copy
   5 * of this software and associated documentation files (the "Software"), to deal
   6 * in the Software without restriction, including without limitation the rights
   7 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   8 * copies of the Software, and to permit persons to whom the Software is
   9 * furnished to do so, subject to the following conditions:
  10 *
  11 * The above copyright notice and this permission notice shall be included in
  12 * all copies or substantial portions of the Software.
  13 *
  14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  17 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  18 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  19 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  20 * THE SOFTWARE.
  21 */
  22
  23#include "hw/hw.h"
  24#include "hw/mips/cpudevs.h"
  25#include "qemu/timer.h"
  26
  27#define TIMER_FREQ      100 * 1000 * 1000
  28
  29/* XXX: do not use a global */
  30uint32_t cpu_mips_get_random (CPUMIPSState *env)
  31{
  32    static uint32_t lfsr = 1;
  33    static uint32_t prev_idx = 0;
  34    uint32_t idx;
  35    /* Don't return same value twice, so get another value */
  36    do {
  37        lfsr = (lfsr >> 1) ^ (-(lfsr & 1u) & 0xd0000001u);
  38        idx = lfsr % (env->tlb->nb_tlb - env->CP0_Wired) + env->CP0_Wired;
  39    } while (idx == prev_idx);
  40    prev_idx = idx;
  41    return idx;
  42}
  43
  44/* MIPS R4K timer */
  45static void cpu_mips_timer_update(CPUMIPSState *env)
  46{
  47    uint64_t now, next;
  48    uint32_t wait;
  49
  50    now = qemu_get_clock_ns(vm_clock);
  51    wait = env->CP0_Compare - env->CP0_Count -
  52            (uint32_t)muldiv64(now, TIMER_FREQ, get_ticks_per_sec());
  53    next = now + muldiv64(wait, get_ticks_per_sec(), TIMER_FREQ);
  54    qemu_mod_timer(env->timer, next);
  55}
  56
  57/* Expire the timer.  */
  58static void cpu_mips_timer_expire(CPUMIPSState *env)
  59{
  60    cpu_mips_timer_update(env);
  61    if (env->insn_flags & ISA_MIPS32R2) {
  62        env->CP0_Cause |= 1 << CP0Ca_TI;
  63    }
  64    qemu_irq_raise(env->irq[(env->CP0_IntCtl >> CP0IntCtl_IPTI) & 0x7]);
  65}
  66
  67uint32_t cpu_mips_get_count (CPUMIPSState *env)
  68{
  69    if (env->CP0_Cause & (1 << CP0Ca_DC)) {
  70        return env->CP0_Count;
  71    } else {
  72        uint64_t now;
  73
  74        now = qemu_get_clock_ns(vm_clock);
  75        if (qemu_timer_pending(env->timer)
  76            && qemu_timer_expired(env->timer, now)) {
  77            /* The timer has already expired.  */
  78            cpu_mips_timer_expire(env);
  79        }
  80
  81        return env->CP0_Count +
  82            (uint32_t)muldiv64(now, TIMER_FREQ, get_ticks_per_sec());
  83    }
  84}
  85
  86void cpu_mips_store_count (CPUMIPSState *env, uint32_t count)
  87{
  88    if (env->CP0_Cause & (1 << CP0Ca_DC))
  89        env->CP0_Count = count;
  90    else {
  91        /* Store new count register */
  92        env->CP0_Count =
  93            count - (uint32_t)muldiv64(qemu_get_clock_ns(vm_clock),
  94                                       TIMER_FREQ, get_ticks_per_sec());
  95        /* Update timer timer */
  96        cpu_mips_timer_update(env);
  97    }
  98}
  99
 100void cpu_mips_store_compare (CPUMIPSState *env, uint32_t value)
 101{
 102    env->CP0_Compare = value;
 103    if (!(env->CP0_Cause & (1 << CP0Ca_DC)))
 104        cpu_mips_timer_update(env);
 105    if (env->insn_flags & ISA_MIPS32R2)
 106        env->CP0_Cause &= ~(1 << CP0Ca_TI);
 107    qemu_irq_lower(env->irq[(env->CP0_IntCtl >> CP0IntCtl_IPTI) & 0x7]);
 108}
 109
 110void cpu_mips_start_count(CPUMIPSState *env)
 111{
 112    cpu_mips_store_count(env, env->CP0_Count);
 113}
 114
 115void cpu_mips_stop_count(CPUMIPSState *env)
 116{
 117    /* Store the current value */
 118    env->CP0_Count += (uint32_t)muldiv64(qemu_get_clock_ns(vm_clock),
 119                                         TIMER_FREQ, get_ticks_per_sec());
 120}
 121
 122static void mips_timer_cb (void *opaque)
 123{
 124    CPUMIPSState *env;
 125
 126    env = opaque;
 127#if 0
 128    qemu_log("%s\n", __func__);
 129#endif
 130
 131    if (env->CP0_Cause & (1 << CP0Ca_DC))
 132        return;
 133
 134    /* ??? This callback should occur when the counter is exactly equal to
 135       the comparator value.  Offset the count by one to avoid immediately
 136       retriggering the callback before any virtual time has passed.  */
 137    env->CP0_Count++;
 138    cpu_mips_timer_expire(env);
 139    env->CP0_Count--;
 140}
 141
 142void cpu_mips_clock_init (CPUMIPSState *env)
 143{
 144    env->timer = qemu_new_timer_ns(vm_clock, &mips_timer_cb, env);
 145    env->CP0_Compare = 0;
 146    cpu_mips_store_count(env, 1);
 147}
 148