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authorPreeti U Murthy <preeti@linux.vnet.ibm.com>2014-02-26 05:39:06 +0530
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2014-03-05 15:57:04 +1100
commit0d94873011a10cea78d1bc0ba8cfc4203559d534 (patch)
tree852cdaaf289b4c80b80f908fd459d161d12721a8
parent97eb001f03494758a938300908b88929163650ce (diff)
downloadop-kernel-dev-0d94873011a10cea78d1bc0ba8cfc4203559d534.zip
op-kernel-dev-0d94873011a10cea78d1bc0ba8cfc4203559d534.tar.gz
cpuidle/powernv: Add "Fast-Sleep" CPU idle state
Fast sleep is one of the deep idle states on Power8 in which local timers of CPUs stop. On PowerPC we do not have an external clock device which can handle wakeup of such CPUs. Now that we have the support in the tick broadcast framework for archs that do not sport such a device and the low level support for fast sleep, enable it in the cpuidle framework on PowerNV. Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
-rw-r--r--arch/powerpc/Kconfig2
-rw-r--r--arch/powerpc/kernel/time.c4
-rw-r--r--drivers/cpuidle/cpuidle-powernv.c34
3 files changed, 39 insertions, 1 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 957bf34..b841420 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -130,6 +130,8 @@ config PPC
select GENERIC_CMOS_UPDATE
select GENERIC_TIME_VSYSCALL_OLD
select GENERIC_CLOCKEVENTS
+ select GENERIC_CLOCKEVENTS_BROADCAST if SMP
+ select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select GENERIC_STRNCPY_FROM_USER
select GENERIC_STRNLEN_USER
select HAVE_MOD_ARCH_SPECIFIC
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index df2989b..122a580 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -42,6 +42,7 @@
#include <linux/timex.h>
#include <linux/kernel_stat.h>
#include <linux/time.h>
+#include <linux/clockchips.h>
#include <linux/init.h>
#include <linux/profile.h>
#include <linux/cpu.h>
@@ -106,7 +107,7 @@ struct clock_event_device decrementer_clockevent = {
.irq = 0,
.set_next_event = decrementer_set_next_event,
.set_mode = decrementer_set_mode,
- .features = CLOCK_EVT_FEAT_ONESHOT,
+ .features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP,
};
EXPORT_SYMBOL(decrementer_clockevent);
@@ -944,6 +945,7 @@ void __init time_init(void)
clocksource_init();
init_decrementer_clockevent();
+ tick_setup_hrtimer_broadcast();
}
diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
index 78fd174..4fb97ce 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -11,6 +11,7 @@
#include <linux/cpuidle.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
+#include <linux/clockchips.h>
#include <asm/machdep.h>
#include <asm/firmware.h>
@@ -49,6 +50,32 @@ static int nap_loop(struct cpuidle_device *dev,
return index;
}
+static int fastsleep_loop(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv,
+ int index)
+{
+ unsigned long old_lpcr = mfspr(SPRN_LPCR);
+ unsigned long new_lpcr;
+
+ if (unlikely(system_state < SYSTEM_RUNNING))
+ return index;
+
+ new_lpcr = old_lpcr;
+ new_lpcr &= ~(LPCR_MER | LPCR_PECE); /* lpcr[mer] must be 0 */
+
+ /* exit powersave upon external interrupt, but not decrementer
+ * interrupt.
+ */
+ new_lpcr |= LPCR_PECE0;
+
+ mtspr(SPRN_LPCR, new_lpcr);
+ power7_sleep();
+
+ mtspr(SPRN_LPCR, old_lpcr);
+
+ return index;
+}
+
/*
* States for dedicated partition case.
*/
@@ -67,6 +94,13 @@ static struct cpuidle_state powernv_states[] = {
.exit_latency = 10,
.target_residency = 100,
.enter = &nap_loop },
+ { /* Fastsleep */
+ .name = "fastsleep",
+ .desc = "fastsleep",
+ .flags = CPUIDLE_FLAG_TIME_VALID,
+ .exit_latency = 10,
+ .target_residency = 100,
+ .enter = &fastsleep_loop },
};
static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
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