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Commit 5b213e7a authored by Rohit Gupta's avatar Rohit Gupta
Browse files

cpufreq: Add a notifer chain that governors can use to report information 



Some modules can benefit from getting additional information cpufreq
governors use to make frequency switch decisions.
This change lays down a basic framework that the governors can use
to report additional information (Eg: CPU's load) information to
the clients that subscribe to cpufreq govinfo notifier chain.

Change-Id: I511b4bdb7d12394a31ce5352ae47553861e49303
Signed-off-by: default avatarRohit Gupta <rohgup@codeaurora.org>
parent 247909f4

drivers/cpufreq/cpufreq.c

+20 −1
Original line number Diff line number Diff line
@@ -80,6 +80,7 @@ static void handle_update(struct work_struct *work); 
 */

static BLOCKING_NOTIFIER_HEAD(cpufreq_policy_notifier_list);

static struct srcu_notifier_head cpufreq_transition_notifier_list;

struct atomic_notifier_head cpufreq_govinfo_notifier_list;



static bool init_cpufreq_transition_notifier_list_called;

static int __init init_cpufreq_transition_notifier_list(void)
@@ -90,6 +91,15 @@ static int __init init_cpufreq_transition_notifier_list(void) 
}

pure_initcall(init_cpufreq_transition_notifier_list);



static bool init_cpufreq_govinfo_notifier_list_called;

static int __init init_cpufreq_govinfo_notifier_list(void)

{

	ATOMIC_INIT_NOTIFIER_HEAD(&cpufreq_govinfo_notifier_list);

	init_cpufreq_govinfo_notifier_list_called = true;

	return 0;

}

pure_initcall(init_cpufreq_govinfo_notifier_list);



static int off __read_mostly;

static int cpufreq_disabled(void)

{
@@ -1638,7 +1648,8 @@ int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list) 
	if (cpufreq_disabled())

		return -EINVAL;



	WARN_ON(!init_cpufreq_transition_notifier_list_called);

	WARN_ON(!init_cpufreq_transition_notifier_list_called ||

		!init_cpufreq_govinfo_notifier_list_called);



	switch (list) {

	case CPUFREQ_TRANSITION_NOTIFIER:
@@ -1649,6 +1660,10 @@ int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list) 
		ret = blocking_notifier_chain_register(

				&cpufreq_policy_notifier_list, nb);

		break;

	case CPUFREQ_GOVINFO_NOTIFIER:

		ret = atomic_notifier_chain_register(

				&cpufreq_govinfo_notifier_list, nb);

		break;

	default:

		ret = -EINVAL;

	}
@@ -1683,6 +1698,10 @@ int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list) 
		ret = blocking_notifier_chain_unregister(

				&cpufreq_policy_notifier_list, nb);

		break;

	case CPUFREQ_GOVINFO_NOTIFIER:

		ret = atomic_notifier_chain_unregister(

				&cpufreq_govinfo_notifier_list, nb);

		break;

	default:

		ret = -EINVAL;

	}

include/linux/cpufreq.h

+14 −0
Original line number Diff line number Diff line
@@ -286,6 +286,7 @@ cpufreq_verify_within_cpu_limits(struct cpufreq_policy *policy) 


#define CPUFREQ_TRANSITION_NOTIFIER	(0)

#define CPUFREQ_POLICY_NOTIFIER		(1)

#define CPUFREQ_GOVINFO_NOTIFIER	(2)



/* Transition notifiers */

#define CPUFREQ_PRECHANGE		(0)
@@ -302,12 +303,25 @@ cpufreq_verify_within_cpu_limits(struct cpufreq_policy *policy) 
#define CPUFREQ_CREATE_POLICY		(5)

#define CPUFREQ_REMOVE_POLICY		(6)



/* Govinfo Notifiers */

#define CPUFREQ_LOAD_CHANGE		(0)



#ifdef CONFIG_CPU_FREQ

int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list);

int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list);



void cpufreq_notify_transition(struct cpufreq_policy *policy,

		struct cpufreq_freqs *freqs, unsigned int state);

/*

 * Governor specific info that can be passed to modules that subscribe

 * to CPUFREQ_GOVINFO_NOTIFIER

 */

struct cpufreq_govinfo {

	unsigned int cpu;

	unsigned int load;

	unsigned int sampling_rate_us;

};

extern struct atomic_notifier_head cpufreq_govinfo_notifier_list;



#else /* CONFIG_CPU_FREQ */

static inline int cpufreq_register_notifier(struct notifier_block *nb,