1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3  * QEMU LoongArch constant timer support
4  *
5  * Copyright (c) 2021 Loongson Technology Corporation Limited
6  */
7 
8 #include "qemu/osdep.h"
9 #include "qemu/timer.h"
10 #include "cpu.h"
11 #include "internals.h"
12 #include "cpu-csr.h"
13 
14 #define TIMER_PERIOD                10 /* 10 ns period for 100 MHz frequency */
15 #define CONSTANT_TIMER_TICK_MASK    0xfffffffffffcUL
16 #define CONSTANT_TIMER_ENABLE       0x1UL
17 
18 uint64_t cpu_loongarch_get_constant_timer_counter(LoongArchCPU *cpu)
19 {
20     return qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) / TIMER_PERIOD;
21 }
22 
23 uint64_t cpu_loongarch_get_constant_timer_ticks(LoongArchCPU *cpu)
24 {
25     uint64_t now, expire;
26 
27     now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
28     expire = timer_expire_time_ns(&cpu->timer);
29 
30     return (expire - now) / TIMER_PERIOD;
31 }
32 
33 void cpu_loongarch_store_constant_timer_config(LoongArchCPU *cpu,
34                                                uint64_t value)
35 {
36     CPULoongArchState *env = &cpu->env;
37     uint64_t now, next;
38 
39     env->CSR_TCFG = value;
40     if (value & CONSTANT_TIMER_ENABLE) {
41         now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
42         next = now + (value & CONSTANT_TIMER_TICK_MASK) * TIMER_PERIOD;
43         timer_mod(&cpu->timer, next);
44     } else {
45         timer_del(&cpu->timer);
46     }
47 }
48 
49 void loongarch_constant_timer_cb(void *opaque)
50 {
51     LoongArchCPU *cpu  = opaque;
52     CPULoongArchState *env = &cpu->env;
53     uint64_t now, next;
54 
55     if (FIELD_EX64(env->CSR_TCFG, CSR_TCFG, PERIODIC)) {
56         now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
57         next = now + (env->CSR_TCFG & CONSTANT_TIMER_TICK_MASK) * TIMER_PERIOD;
58         timer_mod(&cpu->timer, next);
59     } else {
60         env->CSR_TCFG = FIELD_DP64(env->CSR_TCFG, CSR_TCFG, EN, 0);
61     }
62 
63     loongarch_cpu_set_irq(opaque, IRQ_TIMER, 1);
64 }
65