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