diff options
author | Dave Martin <dave.martin@linaro.org> | 2012-12-10 17:19:57 +0000 |
---|---|---|
committer | Nicolas Pitre <nicolas.pitre@linaro.org> | 2013-06-20 00:45:16 -0400 |
commit | 80899af2e864a8a546f6d8f46bccdc1014e9fbd0 (patch) | |
tree | 9caa7e3d34db656f98c0884da02448fb2285d2f1 /arch/arm/common/bL_switcher.c | |
parent | 976e214051cea025f8f55624b254a4e8fe44cd53 (diff) |
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: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Diffstat (limited to 'arch/arm/common/bL_switcher.c')
-rw-r--r-- | arch/arm/common/bL_switcher.c | 27 |
1 files changed, 25 insertions, 2 deletions
diff --git a/arch/arm/common/bL_switcher.c b/arch/arm/common/bL_switcher.c index d18bfdb5dd0..bda51ca23eb 100644 --- a/arch/arm/common/bL_switcher.c +++ b/arch/arm/common/bL_switcher.c @@ -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> @@ -345,6 +346,7 @@ 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; @@ -456,9 +458,11 @@ 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; } @@ -467,6 +471,7 @@ 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; } @@ -479,9 +484,10 @@ 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; } @@ -493,9 +499,11 @@ 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; @@ -540,6 +548,7 @@ 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, @@ -597,6 +606,20 @@ 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 while the switcher is active. * We're just not ready to deal with that given the trickery involved. |