2 * RISC-V timer helper implementation.
4 * Copyright (c) 2022 Rivos Inc.
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms and conditions of the GNU General Public License,
8 * version 2 or later, as published by the Free Software Foundation.
10 * This program is distributed in the hope it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 * You should have received a copy of the GNU General Public License along with
16 * this program. If not, see <http://www.gnu.org/licenses/>.
19 #include "qemu/osdep.h"
22 #include "time_helper.h"
23 #include "hw/intc/riscv_aclint.h"
25 static void riscv_vstimer_cb(void *opaque
)
27 RISCVCPU
*cpu
= opaque
;
28 CPURISCVState
*env
= &cpu
->env
;
30 riscv_cpu_update_mip(cpu
, MIP_VSTIP
, BOOL_TO_MASK(1));
33 static void riscv_stimer_cb(void *opaque
)
35 RISCVCPU
*cpu
= opaque
;
36 riscv_cpu_update_mip(cpu
, MIP_STIP
, BOOL_TO_MASK(1));
40 * Called when timecmp is written to update the QEMU timer or immediately
41 * trigger timer interrupt if mtimecmp <= current timer value.
43 void riscv_timer_write_timecmp(RISCVCPU
*cpu
, QEMUTimer
*timer
,
44 uint64_t timecmp
, uint64_t delta
,
47 uint64_t diff
, ns_diff
, next
;
48 CPURISCVState
*env
= &cpu
->env
;
49 RISCVAclintMTimerState
*mtimer
= env
->rdtime_fn_arg
;
50 uint32_t timebase_freq
= mtimer
->timebase_freq
;
51 uint64_t rtc_r
= env
->rdtime_fn(env
->rdtime_fn_arg
) + delta
;
53 if (timecmp
<= rtc_r
) {
55 * If we're setting an stimecmp value in the "past",
56 * immediately raise the timer interrupt
58 if (timer_irq
== MIP_VSTIP
) {
61 riscv_cpu_update_mip(cpu
, timer_irq
, BOOL_TO_MASK(1));
65 if (timer_irq
== MIP_VSTIP
) {
68 /* Clear the [V]STIP bit in mip */
69 riscv_cpu_update_mip(cpu
, timer_irq
, BOOL_TO_MASK(0));
71 /* otherwise, set up the future timer interrupt */
72 diff
= timecmp
- rtc_r
;
73 /* back to ns (note args switched in muldiv64) */
74 ns_diff
= muldiv64(diff
, NANOSECONDS_PER_SECOND
, timebase_freq
);
77 * check if ns_diff overflowed and check if the addition would potentially
80 if ((NANOSECONDS_PER_SECOND
> timebase_freq
&& ns_diff
< diff
) ||
81 ns_diff
> INT64_MAX
) {
85 * as it is very unlikely qemu_clock_get_ns will return a value
86 * greater than INT64_MAX, no additional check is needed for an
87 * unsigned integer overflow.
89 next
= qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL
) + ns_diff
;
91 * if ns_diff is INT64_MAX next may still be outside the range
92 * of a signed integer.
94 next
= MIN(next
, INT64_MAX
);
97 timer_mod(timer
, next
);
100 void riscv_timer_init(RISCVCPU
*cpu
)
109 env
->stimer
= timer_new_ns(QEMU_CLOCK_VIRTUAL
, &riscv_stimer_cb
, cpu
);
112 env
->vstimer
= timer_new_ns(QEMU_CLOCK_VIRTUAL
, &riscv_vstimer_cb
, cpu
);