LoongArch: Implement constant timer shutdown interface

[ Upstream commit d43f37b73468c172bc89ac4824a1511b411f0778 ]

When a cpu is hot-unplugged, it is put in idle state and the function
arch_cpu_idle_dead() is called. The timer interrupt for this processor
should be disabled, otherwise there will be pending timer interrupt for
the unplugged cpu, so that vcpu is prevented from giving up scheduling
when system is running in vm mode.

This patch implements the timer shutdown interface so that the constant
timer will be properly disabled when a CPU is hot-unplugged.

Reviewed-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/loongarch/kernel/time.c b/arch/loongarch/kernel/time.c
index d2b7d5df132a9be34cb9ab6269e40f1a79669779..150df6e17bb6ad830c9eb9b4ec5e7a442120f2a1 100644 (file)
--- a/arch/loongarch/kernel/time.c
+++ b/arch/loongarch/kernel/time.c
@@ -58,14 +58,16 @@ static int constant_set_state_oneshot(struct clock_event_device *evt)
        return 0;
 }
 
-static int constant_set_state_oneshot_stopped(struct clock_event_device *evt)
+static int constant_set_state_periodic(struct clock_event_device *evt)
 {
+       unsigned long period;
        unsigned long timer_config;
 
        raw_spin_lock(&state_lock);
 
-       timer_config = csr_read64(LOONGARCH_CSR_TCFG);
-       timer_config &= ~CSR_TCFG_EN;
+       period = const_clock_freq / HZ;
+       timer_config = period & CSR_TCFG_VAL;
+       timer_config |= (CSR_TCFG_PERIOD | CSR_TCFG_EN);
        csr_write64(timer_config, LOONGARCH_CSR_TCFG);
 
        raw_spin_unlock(&state_lock);
@@ -73,16 +75,14 @@ static int constant_set_state_oneshot_stopped(struct clock_event_device *evt)
        return 0;
 }
 
-static int constant_set_state_periodic(struct clock_event_device *evt)
+static int constant_set_state_shutdown(struct clock_event_device *evt)
 {
-       unsigned long period;
        unsigned long timer_config;
 
        raw_spin_lock(&state_lock);
 
-       period = const_clock_freq / HZ;
-       timer_config = period & CSR_TCFG_VAL;
-       timer_config |= (CSR_TCFG_PERIOD | CSR_TCFG_EN);
+       timer_config = csr_read64(LOONGARCH_CSR_TCFG);
+       timer_config &= ~CSR_TCFG_EN;
        csr_write64(timer_config, LOONGARCH_CSR_TCFG);
 
        raw_spin_unlock(&state_lock);
@@ -90,11 +90,6 @@ static int constant_set_state_periodic(struct clock_event_device *evt)
        return 0;
 }
 
-static int constant_set_state_shutdown(struct clock_event_device *evt)
-{
-       return 0;
-}
-
 static int constant_timer_next_event(unsigned long delta, struct clock_event_device *evt)
 {
        unsigned long timer_config;
@@ -156,7 +151,7 @@ int constant_clockevent_init(void)
        cd->rating = 320;
        cd->cpumask = cpumask_of(cpu);
        cd->set_state_oneshot = constant_set_state_oneshot;
-       cd->set_state_oneshot_stopped = constant_set_state_oneshot_stopped;
+       cd->set_state_oneshot_stopped = constant_set_state_shutdown;
        cd->set_state_periodic = constant_set_state_periodic;
        cd->set_state_shutdown = constant_set_state_shutdown;
        cd->set_next_event = constant_timer_next_event;