linux-kernel - [PATCH 1/2] cpuidle: Add interface to get cpuidle

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Message-Id: <20250811072709.761961-1-tianyaxiong@kylinos.cn>
Date: Mon, 11 Aug 2025 15:27:09 +0800
From: Yaxiong Tian <tianyaxiong@...inos.cn>
To: rafael@...nel.org,
	daniel.lezcano@...aro.org,
	lenb@...nel.org,
	robert.moore@...el.com
Cc: linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org,
	acpica-devel@...ts.linux.dev,
	Yaxiong Tian <tianyaxiong@...inos.cn>,
	Shaobo Huang <huangshaobo2075@...tium.com.cn>,
	Yinfeng Wang <wangyinfeng@...tium.com.cn>,
	Xu Wang <wangxu@...tium.com.cn>
Subject: [PATCH 1/2] cpuidle: Add interface to get cpuidle_driver by CPU ID

Some drivers need to obtain the cpuidle_driver via CPU ID before the
cpuidle_device is registered. Therefore, this interface is added.

Tested-by: Shaobo Huang <huangshaobo2075@...tium.com.cn>
Signed-off-by: Yaxiong Tian <tianyaxiong@...inos.cn>
Signed-off-by: Shaobo Huang <huangshaobo2075@...tium.com.cn>
Signed-off-by: Yinfeng Wang <wangyinfeng@...tium.com.cn>
Signed-off-by: Xu Wang<wangxu@...tium.com.cn>
---
 drivers/cpuidle/driver.c | 16 ++++++++++++++++
 include/linux/cpuidle.h  |  4 ++++
 2 files changed, 20 insertions(+)

diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
index 9bbfa594c442..8647f8165863 100644
--- a/drivers/cpuidle/driver.c
+++ b/drivers/cpuidle/driver.c
@@ -353,6 +353,22 @@ struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev)
 }
 EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);
 
+/**
+ * cpuidle_get_cpu_driver_by_cpu - return the driver registered for a CPU.
+ * @cpu_num: a valid cpu num
+ *
+ * Returns a struct cpuidle_driver pointer, or NULL if no driver is registered
+ * for the CPU associated with @cpu.
+ */
+struct cpuidle_driver *cpuidle_get_cpu_driver_by_cpu(int cpu_num)
+{
+	if (cpu_num < 0 || cpu_num >= nr_cpu_ids)
+		return NULL;
+
+	return __cpuidle_get_cpu_driver(cpu_num);
+}
+EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver_by_cpu);
+
 /**
  * cpuidle_driver_state_disabled - Disable or enable an idle state
  * @drv: cpuidle driver owning the state
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index a9ee4fe55dcf..aebbaae6a501 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -200,6 +200,7 @@ extern void cpuidle_disable_device(struct cpuidle_device *dev);
 extern int cpuidle_play_dead(void);
 
 extern struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev);
+extern struct cpuidle_driver *cpuidle_get_cpu_driver_by_cpu(int cpu_num);
 static inline struct cpuidle_device *cpuidle_get_device(void)
 {return __this_cpu_read(cpuidle_devices); }
 #else
@@ -240,6 +241,9 @@ static inline void cpuidle_disable_device(struct cpuidle_device *dev) { }
 static inline int cpuidle_play_dead(void) {return -ENODEV; }
 static inline struct cpuidle_driver *cpuidle_get_cpu_driver(
 	struct cpuidle_device *dev) {return NULL; }
+
+static inline struct cpuidle_driver *cpuidle_get_cpu_driver_by_cpu(
+	int cpu_num) {return NULL; };
 static inline struct cpuidle_device *cpuidle_get_device(void) {return NULL; }
 #endif
 
-- 
2.25.1