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authorSudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>2013-08-23 18:53:15 +0400
committerSudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>2013-09-26 12:48:24 +0400
commit346e7480f1d4740b3d798da60f83f087ea6488b4 (patch)
tree71788df9173d240507f4d091bc63021af767929c /drivers/clocksource
parent037f637767a82907efedda78d3ff405c34020075 (diff)
downloadlinux-346e7480f1d4740b3d798da60f83f087ea6488b4.tar.xz
drivers: clocksource: add CPU PM notifier for ARM architected timer
Few control settings done in architected timer as part of initialisation can be lost when CPU enters deeper power states. They need to be restored when the CPU is (warm)reset again. This patch adds CPU PM notifiers to save the counter control register when entering low power modes and restore it when CPU exits low power. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Acked-by: Olof Johansson <olof@lixom.net> Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
Diffstat (limited to 'drivers/clocksource')
-rw-r--r--drivers/clocksource/arm_arch_timer.c34
1 files changed, 34 insertions, 0 deletions
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 105f8ffa66a8..9338f1ad6100 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -13,6 +13,7 @@
#include <linux/device.h>
#include <linux/smp.h>
#include <linux/cpu.h>
+#include <linux/cpu_pm.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/of_irq.h>
@@ -475,6 +476,33 @@ static struct notifier_block arch_timer_cpu_nb = {
.notifier_call = arch_timer_cpu_notify,
};
+#ifdef CONFIG_CPU_PM
+static unsigned int saved_cntkctl;
+static int arch_timer_cpu_pm_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu)
+{
+ if (action == CPU_PM_ENTER)
+ saved_cntkctl = arch_timer_get_cntkctl();
+ else if (action == CPU_PM_ENTER_FAILED || action == CPU_PM_EXIT)
+ arch_timer_set_cntkctl(saved_cntkctl);
+ return NOTIFY_OK;
+}
+
+static struct notifier_block arch_timer_cpu_pm_notifier = {
+ .notifier_call = arch_timer_cpu_pm_notify,
+};
+
+static int __init arch_timer_cpu_pm_init(void)
+{
+ return cpu_pm_register_notifier(&arch_timer_cpu_pm_notifier);
+}
+#else
+static int __init arch_timer_cpu_pm_init(void)
+{
+ return 0;
+}
+#endif
+
static int __init arch_timer_register(void)
{
int err;
@@ -514,11 +542,17 @@ static int __init arch_timer_register(void)
if (err)
goto out_free_irq;
+ err = arch_timer_cpu_pm_init();
+ if (err)
+ goto out_unreg_notify;
+
/* Immediately configure the timer on the boot CPU */
arch_timer_setup(this_cpu_ptr(arch_timer_evt));
return 0;
+out_unreg_notify:
+ unregister_cpu_notifier(&arch_timer_cpu_nb);
out_free_irq:
if (arch_timer_use_virtual)
free_percpu_irq(arch_timer_ppi[VIRT_PPI], arch_timer_evt);