Commit c0f43751 authored by Dave Martin's avatar Dave Martin Committed by Nicolas Pitre
Browse files

ARM: bL_switcher: Add synchronous enable/disable interface 



Some subsystems will need to know for sure whether the switcher is
enabled or disabled during certain critical regions.

This patch provides a simple mutex-based mechanism to discover
whether the switcher is enabled and temporarily lock out further
enable/disable:

  * bL_switcher_get_enabled() returns true iff the switcher is
    enabled and temporarily inhibits enable/disable.

  * bL_switcher_put_enabled() permits enable/disable of the switcher
    again after a previous call to bL_switcher_get_enabled().

Signed-off-by: default avatarDave Martin <dave.martin@linaro.org>
Signed-off-by: default avatarNicolas Pitre <nico@linaro.org>
parent 7f63037c

arch/arm/common/bL_switcher.c

+25 −2
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <linux/hrtimer.h>

#include <linux/tick.h>

#include <linux/mm.h>

#include <linux/mutex.h>

#include <linux/string.h>

#include <linux/sysfs.h>

#include <linux/irqchip/arm-gic.h>
@@ -302,6 +303,7 @@ EXPORT_SYMBOL_GPL(bL_switch_request); 
 * Activation and configuration code.

 */



static DEFINE_MUTEX(bL_switcher_activation_lock);

static unsigned int bL_switcher_active;

static unsigned int bL_switcher_cpu_original_cluster[NR_CPUS];

static cpumask_t bL_switcher_removed_logical_cpus;
@@ -413,9 +415,11 @@ static int bL_switcher_enable(void) 
{

	int cpu, ret;



	mutex_lock(&bL_switcher_activation_lock);

	cpu_hotplug_driver_lock();

	if (bL_switcher_active) {

		cpu_hotplug_driver_unlock();

		mutex_unlock(&bL_switcher_activation_lock);

		return 0;

	}
@@ -424,6 +428,7 @@ static int bL_switcher_enable(void) 
	ret = bL_switcher_halve_cpus();

	if (ret) {

		cpu_hotplug_driver_unlock();

		mutex_unlock(&bL_switcher_activation_lock);

		return ret;

	}
@@ -436,9 +441,10 @@ static int bL_switcher_enable(void) 
	}



	bL_switcher_active = 1;

	cpu_hotplug_driver_unlock();



	pr_info("big.LITTLE switcher initialized\n");



	cpu_hotplug_driver_unlock();

	mutex_unlock(&bL_switcher_activation_lock);

	return 0;

}
@@ -450,9 +456,11 @@ static void bL_switcher_disable(void) 
	struct bL_thread *t;

	struct task_struct *task;



	mutex_lock(&bL_switcher_activation_lock);

	cpu_hotplug_driver_lock();

	if (!bL_switcher_active) {

		cpu_hotplug_driver_unlock();

		mutex_unlock(&bL_switcher_activation_lock);

		return;

	}

	bL_switcher_active = 0;
@@ -497,6 +505,7 @@ static void bL_switcher_disable(void) 


	bL_switcher_restore_cpus();

	cpu_hotplug_driver_unlock();

	mutex_unlock(&bL_switcher_activation_lock);

}



static ssize_t bL_switcher_active_show(struct kobject *kobj,
@@ -554,6 +563,20 @@ static int __init bL_switcher_sysfs_init(void) 


#endif  /* CONFIG_SYSFS */



bool bL_switcher_get_enabled(void)

{

	mutex_lock(&bL_switcher_activation_lock);



	return bL_switcher_active;

}

EXPORT_SYMBOL_GPL(bL_switcher_get_enabled);



void bL_switcher_put_enabled(void)

{

	mutex_unlock(&bL_switcher_activation_lock);

}

EXPORT_SYMBOL_GPL(bL_switcher_put_enabled);



/*

 * Veto any CPU hotplug operation on those CPUs we've removed

 * while the switcher is active.

arch/arm/include/asm/bL_switcher.h

+3 −0
Original line number Diff line number Diff line
@@ -14,4 +14,7 @@ 


int bL_switch_request(unsigned int cpu, unsigned int new_cluster_id);



bool bL_switcher_get_enabled(void);

void bL_switcher_put_enabled(void);



#endif

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