powernv:idle: Add IDLE_STATE_ENTER_SEQ_NORET macro

Currently all the low-power idle states are expected to wake up
at reset vector 0x100. Which is why the macro IDLE_STATE_ENTER_SEQ
that puts the CPU to an idle state and never returns.

On ISA v3.0, when the ESL and EC bits in the PSSCR are zero, the CPU
is expected to wake up at the next instruction of the idle
instruction.

This patch adds a new macro named IDLE_STATE_ENTER_SEQ_NORET for the
no-return variant and reuses the name IDLE_STATE_ENTER_SEQ
for a variant that allows resuming operation at the instruction next
to the idle-instruction.

Acked-by: Balbir Singh <[e-mail]>
Signed-off-by: Gautham R. Shenoy <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>

arch/powerpc/include/asm/cpuidle.h

···
 
 /* Idle state entry routines */
 #ifdef	CONFIG_PPC_P7_NAP
-#define	IDLE_STATE_ENTER_SEQ(IDLE_INST)				\
+#define IDLE_STATE_ENTER_SEQ(IDLE_INST)                         \
 	/* Magic NAP/SLEEP/WINKLE mode enter sequence */	\
 	std	r0,0(r1);					\
 	ptesync;						\
···
 1:	cmpd	cr0,r0,r0;					\
 	bne	1b;						\
 	IDLE_INST;						\
+
+#define	IDLE_STATE_ENTER_SEQ_NORET(IDLE_INST)			\
+	IDLE_STATE_ENTER_SEQ(IDLE_INST)                         \
 	b	.
 #endif /* CONFIG_PPC_P7_NAP */
 

arch/powerpc/kernel/exceptions-64s.S

···
 	lbz	r3,PACA_THREAD_IDLE_STATE(r13)
 	cmpwi	r3,PNV_THREAD_NAP
 	bgt	10f
-	IDLE_STATE_ENTER_SEQ(PPC_NAP)
+	IDLE_STATE_ENTER_SEQ_NORET(PPC_NAP)
 	/* No return */
 10:
 	cmpwi	r3,PNV_THREAD_SLEEP
 	bgt	2f
-	IDLE_STATE_ENTER_SEQ(PPC_SLEEP)
+	IDLE_STATE_ENTER_SEQ_NORET(PPC_SLEEP)
 	/* No return */
 
 2:
···
 	 */
 	ori	r13,r13,1
 	SET_PACA(r13)
-	IDLE_STATE_ENTER_SEQ(PPC_WINKLE)
+	IDLE_STATE_ENTER_SEQ_NORET(PPC_WINKLE)
 	/* No return */
 4:
 #endif

arch/powerpc/kernel/idle_book3s.S

···
 	stb	r3,PACA_THREAD_IDLE_STATE(r13)
 	cmpwi	cr3,r3,PNV_THREAD_SLEEP
 	bge	cr3,2f
-	IDLE_STATE_ENTER_SEQ(PPC_NAP)
+	IDLE_STATE_ENTER_SEQ_NORET(PPC_NAP)
 	/* No return */
 2:
 	/* Sleep or winkle */
···
 
 common_enter: /* common code for all the threads entering sleep or winkle */
 	bgt	cr3,enter_winkle
-	IDLE_STATE_ENTER_SEQ(PPC_SLEEP)
+	IDLE_STATE_ENTER_SEQ_NORET(PPC_SLEEP)
 
 fastsleep_workaround_at_entry:
 	ori	r15,r15,PNV_CORE_IDLE_LOCK_BIT
···
 enter_winkle:
 	bl	save_sprs_to_stack
 
-	IDLE_STATE_ENTER_SEQ(PPC_WINKLE)
+	IDLE_STATE_ENTER_SEQ_NORET(PPC_WINKLE)
 
 /*
  * r3 - requested stop state
···
 	ld	r4,ADDROFF(pnv_first_deep_stop_state)(r5)
 	cmpd	r3,r4
 	bge	2f
-	IDLE_STATE_ENTER_SEQ(PPC_STOP)
+	IDLE_STATE_ENTER_SEQ_NORET(PPC_STOP)
 2:
 /*
  * Entering deep idle state.
···
 
 	bl	save_sprs_to_stack
 
-	IDLE_STATE_ENTER_SEQ(PPC_STOP)
+	IDLE_STATE_ENTER_SEQ_NORET(PPC_STOP)
 
 _GLOBAL(power7_idle)
 	/* Now check if user or arch enabled NAP mode */