linux-kernel - [PATCH V4 4/9] powernv/cpuidle: Add context management for Fast Sleep

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Date:	Fri, 29 Nov 2013 16:12:21 +0530
From:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
To:	fweisbec@...il.com, paul.gortmaker@...driver.com, paulus@...ba.org,
	shangw@...ux.vnet.ibm.com, rjw@...k.pl, galak@...nel.crashing.org,
	benh@...nel.crashing.org, paulmck@...ux.vnet.ibm.com,
	arnd@...db.de, linux-pm@...r.kernel.org, rostedt@...dmis.org,
	michael@...erman.id.au, john.stultz@...aro.org, tglx@...utronix.de,
	chenhui.zhao@...escale.com, deepthi@...ux.vnet.ibm.com,
	r58472@...escale.com, geoff@...radead.org,
	linux-kernel@...r.kernel.org, srivatsa.bhat@...ux.vnet.ibm.com,
	schwidefsky@...ibm.com, svaidy@...ux.vnet.ibm.com,
	linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH V4 4/9] powernv/cpuidle: Add context management for Fast
 Sleep

From: Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>

Before adding Fast-Sleep into the cpuidle framework, some low level
support needs to be added to enable it. This includes saving and
restoring of certain registers at entry and exit time of this state
respectively just like we do in the NAP idle state.

Signed-off-by: Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>
[Changelog modified by Preeti U. Murthy <preeti@...ux.vnet.ibm.com>]
Signed-off-by: Preeti U. Murthy <preeti@...ux.vnet.ibm.com>
---

 arch/powerpc/include/asm/processor.h |    1 +
 arch/powerpc/kernel/exceptions-64s.S |   10 ++++-
 arch/powerpc/kernel/idle_power7.S    |   63 ++++++++++++++++++++++++----------
 3 files changed, 53 insertions(+), 21 deletions(-)

diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 4f7b047..d7633d0 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -444,6 +444,7 @@ enum idle_boot_override {IDLE_NO_OVERRIDE = 0, IDLE_POWERSAVE_OFF};
 
 extern int powersave_nap;	/* set if nap mode can be used in idle loop */
 extern void power7_nap(void);
+extern void power7_sleep(void);
 
 #ifdef CONFIG_CPU_IDLE_POWERPC_BOOK3S
 extern void update_smt_snooze_delay(int cpu, int residency);
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 9f905e4..b8139fb 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -121,9 +121,10 @@ BEGIN_FTR_SECTION
 	cmpwi	cr1,r13,2
 	/* Total loss of HV state is fatal, we could try to use the
 	 * PIR to locate a PACA, then use an emergency stack etc...
-	 * but for now, let's just stay stuck here
+	 * OPAL v3 based powernv platforms have new idle states
+	 * which fall in this catagory.
 	 */
-	bgt	cr1,.
+	bgt	cr1,8f
 	GET_PACA(r13)
 
 #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
@@ -141,6 +142,11 @@ BEGIN_FTR_SECTION
 	beq	cr1,2f
 	b	.power7_wakeup_noloss
 2:	b	.power7_wakeup_loss
+
+	/* Fast Sleep wakeup on PowerNV */
+8:	GET_PACA(r13)
+	b 	.power7_wakeup_loss
+
 9:
 END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
 #endif /* CONFIG_PPC_P7_NAP */
diff --git a/arch/powerpc/kernel/idle_power7.S b/arch/powerpc/kernel/idle_power7.S
index 847e40e..e4bbca2 100644
--- a/arch/powerpc/kernel/idle_power7.S
+++ b/arch/powerpc/kernel/idle_power7.S
@@ -20,17 +20,27 @@
 
 #undef DEBUG
 
-	.text
+/* Idle state entry routines */
 
-_GLOBAL(power7_idle)
-	/* Now check if user or arch enabled NAP mode */
-	LOAD_REG_ADDRBASE(r3,powersave_nap)
-	lwz	r4,ADDROFF(powersave_nap)(r3)
-	cmpwi	0,r4,0
-	beqlr
-	/* fall through */
+#define	IDLE_STATE_ENTER_SEQ(IDLE_INST)				\
+	/* Magic NAP/SLEEP/WINKLE mode enter sequence */	\
+	std	r0,0(r1);					\
+	ptesync;						\
+	ld	r0,0(r1);					\
+1:	cmp	cr0,r0,r0;					\
+	bne	1b;						\
+	IDLE_INST;						\
+	b	.
 
-_GLOBAL(power7_nap)
+	.text
+
+/*
+ * Pass requested state in r3:
+ * 	0 - nap
+ * 	1 - sleep
+ */
+_GLOBAL(power7_powersave_common)
+	/* Use r3 to pass state nap/sleep/winkle */
 	/* NAP is a state loss, we create a regs frame on the
 	 * stack, fill it up with the state we care about and
 	 * stick a pointer to it in PACAR1. We really only
@@ -79,8 +89,8 @@ _GLOBAL(power7_nap)
 	/* Continue saving state */
 	SAVE_GPR(2, r1)
 	SAVE_NVGPRS(r1)
-	mfcr	r3
-	std	r3,_CCR(r1)
+	mfcr	r4
+	std	r4,_CCR(r1)
 	std	r9,_MSR(r1)
 	std	r1,PACAR1(r13)
 
@@ -89,15 +99,30 @@ _GLOBAL(power7_nap)
 	li	r4,KVM_HWTHREAD_IN_NAP
 	stb	r4,HSTATE_HWTHREAD_STATE(r13)
 #endif
+	cmpwi	cr0,r3,1
+	beq	2f
+	IDLE_STATE_ENTER_SEQ(PPC_NAP)
+	/* No return */
+2:	IDLE_STATE_ENTER_SEQ(PPC_SLEEP)
+	/* No return */
 
-	/* Magic NAP mode enter sequence */
-	std	r0,0(r1)
-	ptesync
-	ld	r0,0(r1)
-1:	cmp	cr0,r0,r0
-	bne	1b
-	PPC_NAP
-	b	.
+_GLOBAL(power7_idle)
+	/* Now check if user or arch enabled NAP mode */
+	LOAD_REG_ADDRBASE(r3,powersave_nap)
+	lwz	r4,ADDROFF(powersave_nap)(r3)
+	cmpwi	0,r4,0
+	beqlr
+	/* fall through */
+
+_GLOBAL(power7_nap)
+	li	r3,0
+	b	power7_powersave_common
+	/* No return */
+
+_GLOBAL(power7_sleep)
+	li	r3,1
+	b	power7_powersave_common
+	/* No return */
 
 _GLOBAL(power7_wakeup_loss)
 	ld	r1,PACAR1(r13)

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