summaryrefslogtreecommitdiffstats
path: root/arch/arm/common
diff options
context:
space:
mode:
authorDave Martin <dave.martin@linaro.org>2012-12-10 18:19:57 +0100
committerNicolas Pitre <nicolas.pitre@linaro.org>2013-09-24 00:38:54 +0200
commitc0f4375146a738bae23e48fa8b5383abf02177cb (patch)
tree271ff2cfeeaa91ebf6c0345814973ad7d67154a1 /arch/arm/common
parentMerge branch 'iks_for_rmk' of git://git.linaro.org/people/nico/linux into dev... (diff)
downloadlinux-c0f4375146a738bae23e48fa8b5383abf02177cb.tar.xz
linux-c0f4375146a738bae23e48fa8b5383abf02177cb.zip
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')
-rw-r--r--arch/arm/common/bL_switcher.c27
1 files changed, 25 insertions, 2 deletions
diff --git a/arch/arm/common/bL_switcher.c b/arch/arm/common/bL_switcher.c
index 335ff76d4c5a..7d98629aa446 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.