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drivers: clocksource: add CPU PM notifier for ARM architected timer

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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.

Change-Id: Ic617dc1a8efd0c5df7a31fb9990b6ead51292df6
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>
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Git-commit 346e7480f1d4740b3d798da60f83f087ea6488b4
Signed-off-by: Trilok Soni <tsoni@codeaurora.org>
This commit is contained in:
Sudeep KarkadaNagesha 2013-08-23 15:53:15 +01:00 committed by Trilok Soni
parent 74a2f3fef0
commit 6a6a0e3e7e
1 changed files with 34 additions and 0 deletions
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34
drivers/clocksource/arm_arch_timer.c
View file

@ -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>
@ -504,6 +505,33 @@ static struct notifier_block arch_timer_cpu_nb __cpuinitdata = {
.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;
@ -543,11 +571,17 @@ 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);