linux-kernel - [PATCH v2 1/2] powerpc: Add helpers for LPCR PECE1 operations

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Date:	Mon, 19 Jan 2015 13:35:26 +0530
From:	"Shreyas B. Prabhu" <shreyas@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	"Shreyas B. Prabhu" <shreyas@...ux.vnet.ibm.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH v2 1/2] powerpc: Add helpers for LPCR PECE1 operations

PECE1 bit in LPCR is used to control whether decrementer can cause exit
from powersaving states. PECE1 bit is cleared before entering fastsleep
or deeper powersaving state and it is set on waking up. Since both
cpuidle and cpu offline operations use these powersaving states, add
helper functions to be used in both these places.

Signed-off-by: Shreyas B. Prabhu <shreyas@...ux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: linuxppc-dev@...ts.ozlabs.org
---
 arch/powerpc/include/asm/reg.h       | 4 ++++
 arch/powerpc/platforms/powernv/smp.c | 4 ++--
 drivers/cpuidle/cpuidle-powernv.c    | 3 +--
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index c870e38..0847303 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -339,6 +339,10 @@
 #define   LPCR_LPES_SH	2
 #define   LPCR_RMI     0x00000002      /* real mode is cache inhibit */
 #define   LPCR_HDICE   0x00000001      /* Hyp Decr enable (HV,PR,EE) */
+/* LPCR PECE1 helpers. Used to disable/enable wake up due to decrementer */
+#define   LPCR_CLEAR_PECE1(old)	(old & ~(u64)LPCR_PECE1)
+#define   LPCR_SET_PECE1(old)	(old | (u64)LPCR_PECE1)
+
 #ifndef SPRN_LPID
 #define SPRN_LPID	0x13F	/* Logical Partition Identifier */
 #endif
diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
index 781ec45..ab61cb0 100644
--- a/arch/powerpc/platforms/powernv/smp.c
+++ b/arch/powerpc/platforms/powernv/smp.c
@@ -165,7 +165,7 @@ static void pnv_smp_cpu_kill_self(void)
 	/* We don't want to take decrementer interrupts while we are offline,
 	 * so clear LPCR:PECE1. We keep PECE2 enabled.
 	 */
-	mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);
+	mtspr(SPRN_LPCR, LPCR_CLEAR_PECE1(mfspr(SPRN_LPCR)));
 	while (!generic_check_cpu_restart(cpu)) {
 
 		ppc64_runlatch_off();
@@ -203,7 +203,7 @@ static void pnv_smp_cpu_kill_self(void)
 		if (!generic_check_cpu_restart(cpu))
 			DBG("CPU%d Unexpected exit while offline !\n", cpu);
 	}
-	mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_PECE1);
+	mtspr(SPRN_LPCR, LPCR_SET_PECE1(mfspr(SPRN_LPCR)));
 	DBG("CPU%d coming online...\n", cpu);
 }
 
diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
index de61b9a..ed0be4c 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -69,11 +69,10 @@ static int fastsleep_loop(struct cpuidle_device *dev,
 	if (unlikely(system_state < SYSTEM_RUNNING))
 		return index;
 
-	new_lpcr = old_lpcr;
 	/* Do not exit powersave upon decrementer as we've setup the timer
 	 * offload.
 	 */
-	new_lpcr &= ~LPCR_PECE1;
+	new_lpcr = LPCR_CLEAR_PECE1(old_lpcr);
 
 	mtspr(SPRN_LPCR, new_lpcr);
 	power7_sleep();
-- 
1.9.3

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