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From: Shawn Guo <shawn.guo@linaro.org>
To: Marc Zyngier <maz@kernel.org>, "Rafael J . Wysocki" <rafael@kernel.org>
Cc: Valentin Schneider <valentin.schneider@arm.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Maulik Shah <quic_mkshah@quicinc.com>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	devicetree@vger.kernel.org, linux-arm-msm@vger.kernel.org,
	linux-kernel@vger.kernel.org, Shawn Guo <shawn.guo@linaro.org>
Subject: [PATCH v6 1/3] PM: cpu: Add CPU_LAST_PM_ENTER and CPU_FIRST_PM_EXIT support
Date: Wed, 23 Feb 2022 20:55:34 +0800	[thread overview]
Message-ID: <20220223125536.230224-2-shawn.guo@linaro.org> (raw)
In-Reply-To: <20220223125536.230224-1-shawn.guo@linaro.org>

It becomes a common situation on some platforms that certain hardware
setup needs to be done on the last standing cpu, and rpmh-rsc[1] is such
an existing example.  As figuring out the last standing cpu is really
something generic, it adds CPU_LAST_PM_ENTER (and CPU_FIRST_PM_EXIT)
event support to cpu_pm helper, so that individual driver can be
notified when the last standing cpu is about to enter low power state.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/soc/qcom/rpmh-rsc.c?id=v5.16#n773

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
---
 include/linux/cpu_pm.h | 15 +++++++++++++++
 kernel/cpu_pm.c        | 33 +++++++++++++++++++++++++++++++--
 2 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/include/linux/cpu_pm.h b/include/linux/cpu_pm.h
index 552b8f9ea05e..153344307b7c 100644
--- a/include/linux/cpu_pm.h
+++ b/include/linux/cpu_pm.h
@@ -55,6 +55,21 @@ enum cpu_pm_event {
 
 	/* A cpu power domain is exiting a low power state */
 	CPU_CLUSTER_PM_EXIT,
+
+	/*
+	 * A cpu is entering a low power state after all other cpus
+	 * in the system have entered the lower power state.
+	 */
+	CPU_LAST_PM_ENTER,
+
+	/* The last cpu failed to enter a low power state */
+	CPU_LAST_PM_ENTER_FAILED,
+
+	/*
+	 * A cpu is exiting a low power state before any other cpus
+	 * in the system exits the low power state.
+	 */
+	CPU_FIRST_PM_EXIT,
 };
 
 #ifdef CONFIG_CPU_PM
diff --git a/kernel/cpu_pm.c b/kernel/cpu_pm.c
index 246efc74e3f3..7c104446e1e9 100644
--- a/kernel/cpu_pm.c
+++ b/kernel/cpu_pm.c
@@ -26,6 +26,8 @@ static struct {
 	.lock  = __RAW_SPIN_LOCK_UNLOCKED(cpu_pm_notifier.lock),
 };
 
+static atomic_t cpus_in_pm;
+
 static int cpu_pm_notify(enum cpu_pm_event event)
 {
 	int ret;
@@ -116,7 +118,20 @@ EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier);
  */
 int cpu_pm_enter(void)
 {
-	return cpu_pm_notify_robust(CPU_PM_ENTER, CPU_PM_ENTER_FAILED);
+	int ret;
+
+	ret = cpu_pm_notify_robust(CPU_PM_ENTER, CPU_PM_ENTER_FAILED);
+	if (ret)
+		return ret;
+
+	if (atomic_inc_return(&cpus_in_pm) == num_online_cpus()) {
+		ret = cpu_pm_notify_robust(CPU_LAST_PM_ENTER,
+					   CPU_LAST_PM_ENTER_FAILED);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
 }
 EXPORT_SYMBOL_GPL(cpu_pm_enter);
 
@@ -134,7 +149,21 @@ EXPORT_SYMBOL_GPL(cpu_pm_enter);
  */
 int cpu_pm_exit(void)
 {
-	return cpu_pm_notify(CPU_PM_EXIT);
+	int ret;
+
+	ret = cpu_pm_notify(CPU_PM_EXIT);
+	if (ret)
+		return ret;
+
+	if (atomic_read(&cpus_in_pm) == num_online_cpus()) {
+		ret = cpu_pm_notify(CPU_FIRST_PM_EXIT);
+		if (ret)
+			return ret;
+	}
+
+	atomic_dec(&cpus_in_pm);
+
+	return 0;
 }
 EXPORT_SYMBOL_GPL(cpu_pm_exit);
 
-- 
2.25.1


  reply	other threads:[~2022-02-23 12:57 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-23 12:55 [PATCH v6 0/3] Add Qualcomm MPM irqchip driver support Shawn Guo
2022-02-23 12:55 ` Shawn Guo [this message]
2022-02-23 19:30   ` [PATCH v6 1/3] PM: cpu: Add CPU_LAST_PM_ENTER and CPU_FIRST_PM_EXIT support Sudeep Holla
2022-02-25  4:33     ` Shawn Guo
2022-02-25 14:20       ` Sudeep Holla
2022-02-23 12:55 ` [PATCH v6 2/3] dt-bindings: interrupt-controller: Add Qualcomm MPM support Shawn Guo
2022-02-23 12:55 ` [PATCH v6 3/3] irqchip: Add Qualcomm MPM controller driver Shawn Guo
2022-02-23 23:43   ` kernel test robot
2022-02-24  2:10     ` Shawn Guo
2022-02-24  2:10       ` Shawn Guo
2022-02-25  8:54       ` Marc Zyngier
2022-02-25  8:54         ` Marc Zyngier
2022-05-04 14:08 ` [PATCH v6 0/3] Add Qualcomm MPM irqchip driver support Ulf Hansson
2022-05-04 19:21   ` Sudeep Holla

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