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115 lines
3.4 KiB
C
115 lines
3.4 KiB
C
/*
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* RISC-V timer helper implementation.
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*
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* Copyright (c) 2022 Rivos Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2 or later, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "qemu/osdep.h"
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#include "qemu/log.h"
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#include "cpu_bits.h"
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#include "time_helper.h"
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#include "hw/intc/riscv_aclint.h"
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static void riscv_vstimer_cb(void *opaque)
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{
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RISCVCPU *cpu = opaque;
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CPURISCVState *env = &cpu->env;
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env->vstime_irq = 1;
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riscv_cpu_update_mip(cpu, MIP_VSTIP, BOOL_TO_MASK(1));
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}
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static void riscv_stimer_cb(void *opaque)
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{
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RISCVCPU *cpu = opaque;
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riscv_cpu_update_mip(cpu, MIP_STIP, BOOL_TO_MASK(1));
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}
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/*
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* Called when timecmp is written to update the QEMU timer or immediately
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* trigger timer interrupt if mtimecmp <= current timer value.
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*/
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void riscv_timer_write_timecmp(RISCVCPU *cpu, QEMUTimer *timer,
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uint64_t timecmp, uint64_t delta,
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uint32_t timer_irq)
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{
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uint64_t diff, ns_diff, next;
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CPURISCVState *env = &cpu->env;
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RISCVAclintMTimerState *mtimer = env->rdtime_fn_arg;
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uint32_t timebase_freq = mtimer->timebase_freq;
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uint64_t rtc_r = env->rdtime_fn(env->rdtime_fn_arg) + delta;
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if (timecmp <= rtc_r) {
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/*
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* If we're setting an stimecmp value in the "past",
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* immediately raise the timer interrupt
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*/
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if (timer_irq == MIP_VSTIP) {
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env->vstime_irq = 1;
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}
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riscv_cpu_update_mip(cpu, timer_irq, BOOL_TO_MASK(1));
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return;
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}
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if (timer_irq == MIP_VSTIP) {
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env->vstime_irq = 0;
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}
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/* Clear the [V]STIP bit in mip */
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riscv_cpu_update_mip(cpu, timer_irq, BOOL_TO_MASK(0));
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/* otherwise, set up the future timer interrupt */
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diff = timecmp - rtc_r;
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/* back to ns (note args switched in muldiv64) */
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ns_diff = muldiv64(diff, NANOSECONDS_PER_SECOND, timebase_freq);
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/*
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* check if ns_diff overflowed and check if the addition would potentially
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* overflow
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*/
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if ((NANOSECONDS_PER_SECOND > timebase_freq && ns_diff < diff) ||
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ns_diff > INT64_MAX) {
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next = INT64_MAX;
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} else {
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/*
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* as it is very unlikely qemu_clock_get_ns will return a value
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* greater than INT64_MAX, no additional check is needed for an
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* unsigned integer overflow.
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*/
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next = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + ns_diff;
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/*
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* if ns_diff is INT64_MAX next may still be outside the range
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* of a signed integer.
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*/
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next = MIN(next, INT64_MAX);
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}
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timer_mod(timer, next);
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}
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void riscv_timer_init(RISCVCPU *cpu)
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{
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CPURISCVState *env;
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if (!cpu) {
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return;
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}
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env = &cpu->env;
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env->stimer = timer_new_ns(QEMU_CLOCK_VIRTUAL, &riscv_stimer_cb, cpu);
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env->stimecmp = 0;
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env->vstimer = timer_new_ns(QEMU_CLOCK_VIRTUAL, &riscv_vstimer_cb, cpu);
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env->vstimecmp = 0;
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}
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