5 files changed, 77 insertions, 0 deletions
diff --git a/target/loongarch/constant_timer.c b/target/loongarch/constant_timer.c
new file mode 100644
index 0000000000..1851f53fd6
--- /dev/null
+++ b/target/loongarch/constant_timer.c
@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * QEMU LoongArch constant timer support
+ *
+ * Copyright (c) 2021 Loongson Technology Corporation Limited
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/timer.h"
+#include "cpu.h"
+#include "internals.h"
+#include "cpu-csr.h"
+
+#define TIMER_PERIOD                10 /* 10 ns period for 100 MHz frequency */
+#define CONSTANT_TIMER_TICK_MASK    0xfffffffffffcUL
+#define CONSTANT_TIMER_ENABLE       0x1UL
+
+uint64_t cpu_loongarch_get_constant_timer_counter(LoongArchCPU *cpu)
+{
+    return qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) / TIMER_PERIOD;
+}
+
+uint64_t cpu_loongarch_get_constant_timer_ticks(LoongArchCPU *cpu)
+{
+    uint64_t now, expire;
+
+    now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+    expire = timer_expire_time_ns(&cpu->timer);
+
+    return (expire - now) / TIMER_PERIOD;
+}
+
+void cpu_loongarch_store_constant_timer_config(LoongArchCPU *cpu,
+                                               uint64_t value)
+{
+    CPULoongArchState *env = &cpu->env;
+    uint64_t now, next;
+
+    env->CSR_TCFG = value;
+    if (value & CONSTANT_TIMER_ENABLE) {
+        now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+        next = now + (value & CONSTANT_TIMER_TICK_MASK) * TIMER_PERIOD;
+        timer_mod(&cpu->timer, next);
+    } else {
+        timer_del(&cpu->timer);
+    }
+}
+
+void loongarch_constant_timer_cb(void *opaque)
+{
+    LoongArchCPU *cpu  = opaque;
+    CPULoongArchState *env = &cpu->env;
+    uint64_t now, next;
+
+    if (FIELD_EX64(env->CSR_TCFG, CSR_TCFG, PERIODIC)) {
+        now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+        next = now + (env->CSR_TCFG & CONSTANT_TIMER_TICK_MASK) * TIMER_PERIOD;
+        timer_mod(&cpu->timer, next);
+    } else {
+        env->CSR_TCFG = FIELD_DP64(env->CSR_TCFG, CSR_TCFG, EN, 0);
+    }
+
+    loongarch_cpu_set_irq(opaque, IRQ_TIMER, 1);
+}
diff --git a/target/loongarch/cpu.c b/target/loongarch/cpu.c
index 01a0b4878a..5ec0ba1cfa 100644
--- a/target/loongarch/cpu.c
+++ b/target/loongarch/cpu.c
@@ -495,6 +495,8 @@ static void loongarch_cpu_init(Object *obj)
 
     cpu_set_cpustate_pointers(cpu);
     qdev_init_gpio_in(DEVICE(cpu), loongarch_cpu_set_irq, N_IRQS);
+    timer_init_ns(&cpu->timer, QEMU_CLOCK_VIRTUAL,
+                  &loongarch_constant_timer_cb, cpu);
 }
 
 static ObjectClass *loongarch_cpu_class_by_name(const char *cpu_model)
diff --git a/target/loongarch/cpu.h b/target/loongarch/cpu.h
index b983ce241c..2081902f2e 100644
--- a/target/loongarch/cpu.h
+++ b/target/loongarch/cpu.h
@@ -11,6 +11,7 @@
 #include "exec/cpu-defs.h"
 #include "fpu/softfloat-types.h"
 #include "hw/registerfields.h"
+#include "qemu/timer.h"
 
 #define TCG_GUEST_DEFAULT_MO (0)
 
@@ -185,6 +186,8 @@ extern const char * const regnames[32];
 extern const char * const fregnames[32];
 
 #define N_IRQS      13
+#define IRQ_TIMER   11
+#define IRQ_IPI     12
 
 #define LOONGARCH_STLB         2048 /* 2048 STLB */
 #define LOONGARCH_MTLB         64   /* 64 MTLB */
@@ -295,6 +298,7 @@ struct ArchCPU {
 
     CPUNegativeOffsetState neg;
     CPULoongArchState env;
+    QEMUTimer timer;
 };
 
 #define TYPE_LOONGARCH_CPU "loongarch-cpu"
diff --git a/target/loongarch/internals.h b/target/loongarch/internals.h
index 69183e8bb5..4b1bcd7c0f 100644
--- a/target/loongarch/internals.h
+++ b/target/loongarch/internals.h
@@ -32,6 +32,12 @@ extern const VMStateDescription vmstate_loongarch_cpu;
 
 void loongarch_cpu_set_irq(void *opaque, int irq, int level);
 
+void loongarch_constant_timer_cb(void *opaque);
+uint64_t cpu_loongarch_get_constant_timer_counter(LoongArchCPU *cpu);
+uint64_t cpu_loongarch_get_constant_timer_ticks(LoongArchCPU *cpu);
+void cpu_loongarch_store_constant_timer_config(LoongArchCPU *cpu,
+                                               uint64_t value);
+
 bool loongarch_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
                             MMUAccessType access_type, int mmu_idx,
                             bool probe, uintptr_t retaddr);
diff --git a/target/loongarch/meson.build b/target/loongarch/meson.build
index 435cc75999..04e15ba1e3 100644
--- a/target/loongarch/meson.build
+++ b/target/loongarch/meson.build
@@ -18,6 +18,7 @@ loongarch_softmmu_ss = ss.source_set()
 loongarch_softmmu_ss.add(files(
   'machine.c',
   'tlb_helper.c',
+  'constant_timer.c',
 ))
 
 loongarch_ss.add_all(when: 'CONFIG_TCG', if_true: [loongarch_tcg_ss])