diff options
Diffstat (limited to 'target/mips/cp0_timer.c')
| -rw-r--r-- | target/mips/cp0_timer.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/target/mips/cp0_timer.c b/target/mips/cp0_timer.c new file mode 100644 index 0000000..a9a58c5 --- /dev/null +++ b/target/mips/cp0_timer.c @@ -0,0 +1,164 @@ +/* + * QEMU MIPS timer support + * + * 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 "qemu/osdep.h" +#include "hw/mips/cpudevs.h" +#include "qemu/timer.h" +#include "sysemu/kvm.h" + +#define TIMER_PERIOD 10 /* 10 ns period for 100 Mhz frequency */ + +/* XXX: do not use a global */ +uint32_t cpu_mips_get_random (CPUMIPSState *env) +{ + static uint32_t seed = 1; + static uint32_t prev_idx = 0; + uint32_t idx; + uint32_t nb_rand_tlb = env->tlb->nb_tlb - env->CP0_Wired; + + if (nb_rand_tlb == 1) { + return env->tlb->nb_tlb - 1; + } + + /* Don't return same value twice, so get another value */ + do { + /* Use a simple algorithm of Linear Congruential Generator + * from ISO/IEC 9899 standard. */ + seed = 1103515245 * seed + 12345; + idx = (seed >> 16) % nb_rand_tlb + env->CP0_Wired; + } while (idx == prev_idx); + prev_idx = idx; + return idx; +} + +/* MIPS R4K timer */ +static void cpu_mips_timer_update(CPUMIPSState *env) +{ + uint64_t now, next; + uint32_t wait; + + now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); + wait = env->CP0_Compare - env->CP0_Count - (uint32_t)(now / TIMER_PERIOD); + next = now + (uint64_t)wait * TIMER_PERIOD; + timer_mod(env->timer, next); +} + +/* Expire the timer. */ +static void cpu_mips_timer_expire(CPUMIPSState *env) +{ + cpu_mips_timer_update(env); + if (env->insn_flags & ISA_MIPS32R2) { + env->CP0_Cause |= 1 << CP0Ca_TI; + } + qemu_irq_raise(env->irq[(env->CP0_IntCtl >> CP0IntCtl_IPTI) & 0x7]); +} + +uint32_t cpu_mips_get_count (CPUMIPSState *env) +{ + if (env->CP0_Cause & (1 << CP0Ca_DC)) { + return env->CP0_Count; + } else { + uint64_t now; + + now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); + if (timer_pending(env->timer) + && timer_expired(env->timer, now)) { + /* The timer has already expired. */ + cpu_mips_timer_expire(env); + } + + return env->CP0_Count + (uint32_t)(now / TIMER_PERIOD); + } +} + +void cpu_mips_store_count (CPUMIPSState *env, uint32_t count) +{ + /* + * This gets called from cpu_state_reset(), potentially before timer init. + * So env->timer may be NULL, which is also the case with KVM enabled so + * treat timer as disabled in that case. + */ + if (env->CP0_Cause & (1 << CP0Ca_DC) || !env->timer) + env->CP0_Count = count; + else { + /* Store new count register */ + env->CP0_Count = count - + (uint32_t)(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) / TIMER_PERIOD); + /* Update timer timer */ + cpu_mips_timer_update(env); + } +} + +void cpu_mips_store_compare (CPUMIPSState *env, uint32_t value) +{ + env->CP0_Compare = value; + if (!(env->CP0_Cause & (1 << CP0Ca_DC))) + cpu_mips_timer_update(env); + if (env->insn_flags & ISA_MIPS32R2) + env->CP0_Cause &= ~(1 << CP0Ca_TI); + qemu_irq_lower(env->irq[(env->CP0_IntCtl >> CP0IntCtl_IPTI) & 0x7]); +} + +void cpu_mips_start_count(CPUMIPSState *env) +{ + cpu_mips_store_count(env, env->CP0_Count); +} + +void cpu_mips_stop_count(CPUMIPSState *env) +{ + /* Store the current value */ + env->CP0_Count += (uint32_t)(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) / + TIMER_PERIOD); +} + +static void mips_timer_cb (void *opaque) +{ + CPUMIPSState *env; + + env = opaque; +#if 0 + qemu_log("%s\n", __func__); +#endif + + if (env->CP0_Cause & (1 << CP0Ca_DC)) + return; + + /* ??? This callback should occur when the counter is exactly equal to + the comparator value. Offset the count by one to avoid immediately + retriggering the callback before any virtual time has passed. */ + env->CP0_Count++; + cpu_mips_timer_expire(env); + env->CP0_Count--; +} + +void cpu_mips_clock_init (MIPSCPU *cpu) +{ + CPUMIPSState *env = &cpu->env; + + /* + * If we're in KVM mode, don't create the periodic timer, that is handled in + * kernel. + */ + if (!kvm_enabled()) { + env->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, &mips_timer_cb, env); + } +} |