[PATCH] cpufreq: Add CPU frequency policy change notification support

[Tony W Wang-oc]

Implemented CPUFREQ_CHANGE_POLICY notification in cpufreq subsystem.
This enhancement allows kernel modules to be notified when a CPU frequency
policy is modified, facilitating more integrated system management.
The notification is dispatched after a successful governor switch during
policy updates.

Signed-off-by: Tony W Wang-oc <TonyWWang-oc@xxxxxxxxxxx>
---
 drivers/cpufreq/cpufreq.c | 2 ++
 include/linux/cpufreq.h   | 1 +
 2 files changed, 3 insertions(+)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index a7a69f4d7675..b35fed93bca4 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2707,6 +2707,8 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
 		ret = cpufreq_start_governor(policy);
 		if (!ret) {
 			pr_debug("governor change\n");
+			blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+						     CPUFREQ_CHANGE_POLICY, policy);
 			return 0;
 		}
 		cpufreq_exit_governor(policy);
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index cc894fc38971..b1cc9138e801 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -528,6 +528,7 @@ static inline void cpufreq_resume(void) {}
 /* Policy Notifiers  */
 #define CPUFREQ_CREATE_POLICY		(0)
 #define CPUFREQ_REMOVE_POLICY		(1)
+#define CPUFREQ_CHANGE_POLICY		(2)
 
 #ifdef CONFIG_CPU_FREQ
 int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list);
-- 
2.25.1