[PATCH v5 1/3] cpuidle: psci: Call cpu_cluster_pm_enter() on the last CPU

Shawn Guo
2022-02-16T13:28:53Z

Make a call to cpu_cluster_pm_enter() on the last CPU going to low power
state (and cpu_cluster_pm_exit() on the firt CPU coming back), so that
platforms can be notified to set up hardware for getting into the cluster
low power state.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
---
drivers/cpuidle/cpuidle-psci.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
index b51b5df08450..c748c1a7d7b1 100644
--- a/drivers/cpuidle/cpuidle-psci.c
+++ b/drivers/cpuidle/cpuidle-psci.c
@@ -37,6 +37,7 @@ struct psci_cpuidle_data {
static DEFINE_PER_CPU_READ_MOSTLY(struct psci_cpuidle_data, psci_cpuidle_data);
static DEFINE_PER_CPU(u32, domain_state);
static bool psci_cpuidle_use_cpuhp;
+static atomic_t cpus_in_idle;

void psci_set_domain_state(u32 state)
{
@@ -67,6 +68,14 @@ static int __psci_enter_domain_idle_state(struct cpuidle_device *dev,
if (ret)
return -1;

+ if (atomic_inc_return(&cpus_in_idle) == num_online_cpus()) {
+ ret = cpu_cluster_pm_enter();
+ if (ret) {
+ ret = -1;
+ goto dec_atomic;
+ }
+ }
+
/* Do runtime PM to manage a hierarchical CPU toplogy. */
rcu_irq_enter_irqson();
if (s2idle)
@@ -88,6 +97,10 @@ static int __psci_enter_domain_idle_state(struct cpuidle_device *dev,
pm_runtime_get_sync(pd_dev);
rcu_irq_exit_irqson();

+ if (atomic_read(&cpus_in_idle) == num_online_cpus())
+ cpu_cluster_pm_exit();
+dec_atomic:
+ atomic_dec(&cpus_in_idle);
cpu_pm_exit();

/* Clear the domain state to start fresh when back from idle. */
--
2.17.1