From: Dave Martin dave.martin@linaro.org
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 --- arch/arm/common/bL_switcher.c | 27 +++++++++++++++++++++++++-- arch/arm/include/asm/bL_switcher.h | 3 +++ 2 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/arch/arm/common/bL_switcher.c b/arch/arm/common/bL_switcher.c index 335ff76d4c..7d98629aa4 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> @@ -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. diff --git a/arch/arm/include/asm/bL_switcher.h b/arch/arm/include/asm/bL_switcher.h index e0c0bba70b..05d7c4cb94 100644 --- a/arch/arm/include/asm/bL_switcher.h +++ b/arch/arm/include/asm/bL_switcher.h @@ -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