1 files changed, 218 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S
new file mode 100644
index 000000000..3d97fb833
--- /dev/null
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -0,0 +1,218 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *  Copyright 2018, IBM Corporation.
+ *
+ *  This file contains general idle entry/exit functions to save
+ *  and restore stack and NVGPRs which allows C code to call idle
+ *  states that lose GPRs, and it will return transparently with
+ *  SRR1 wakeup reason return value.
+ *
+ *  The platform / CPU caller must ensure SPRs and any other non-GPR
+ *  state is saved and restored correctly, handle KVM, interrupts, etc.
+ */
+
+#include <asm/ppc_asm.h>
+#include <asm/asm-offsets.h>
+#include <asm/ppc-opcode.h>
+#include <asm/cpuidle.h>
+#include <asm/thread_info.h> /* TLF_NAPPING */
+
+#ifdef CONFIG_PPC_P7_NAP
+/*
+ * Desired PSSCR in r3
+ *
+ * No state will be lost regardless of wakeup mechanism (interrupt or NIA).
+ *
+ * An EC=0 type wakeup will return with a value of 0. SRESET wakeup (which can
+ * happen with xscom SRESET and possibly MCE) may clobber volatiles except LR,
+ * and must blr, to return to caller with r3 set according to caller's expected
+ * return code (for Book3S/64 that is SRR1).
+ */
+_GLOBAL(isa300_idle_stop_noloss)
+	mtspr 	SPRN_PSSCR,r3
+	PPC_STOP
+	li	r3,0
+	blr
+
+/*
+ * Desired PSSCR in r3
+ *
+ * GPRs may be lost, so they are saved here. Wakeup is by interrupt only.
+ * The SRESET wakeup returns to this function's caller by calling
+ * idle_return_gpr_loss with r3 set to desired return value.
+ *
+ * A wakeup without GPR loss may alteratively be handled as in
+ * isa300_idle_stop_noloss and blr directly, as an optimisation.
+ *
+ * The caller is responsible for saving/restoring SPRs, MSR, timebase,
+ * etc.
+ */
+_GLOBAL(isa300_idle_stop_mayloss)
+	mtspr 	SPRN_PSSCR,r3
+	std	r1,PACAR1(r13)
+	mflr	r4
+	mfcr	r5
+	/*
+	 * Use the stack red zone rather than a new frame for saving regs since
+	 * in the case of no GPR loss the wakeup code branches directly back to
+	 * the caller without deallocating the stack frame first.
+	 */
+	std	r2,-8*1(r1)
+	std	r14,-8*2(r1)
+	std	r15,-8*3(r1)
+	std	r16,-8*4(r1)
+	std	r17,-8*5(r1)
+	std	r18,-8*6(r1)
+	std	r19,-8*7(r1)
+	std	r20,-8*8(r1)
+	std	r21,-8*9(r1)
+	std	r22,-8*10(r1)
+	std	r23,-8*11(r1)
+	std	r24,-8*12(r1)
+	std	r25,-8*13(r1)
+	std	r26,-8*14(r1)
+	std	r27,-8*15(r1)
+	std	r28,-8*16(r1)
+	std	r29,-8*17(r1)
+	std	r30,-8*18(r1)
+	std	r31,-8*19(r1)
+	std	r4,-8*20(r1)
+	std	r5,-8*21(r1)
+	/* 168 bytes */
+	PPC_STOP
+	b	.	/* catch bugs */
+
+/*
+ * Desired return value in r3
+ *
+ * The idle wakeup SRESET interrupt can call this after calling
+ * to return to the idle sleep function caller with r3 as the return code.
+ *
+ * This must not be used if idle was entered via a _noloss function (use
+ * a simple blr instead).
+ */
+_GLOBAL(idle_return_gpr_loss)
+	ld	r1,PACAR1(r13)
+	ld	r4,-8*20(r1)
+	ld	r5,-8*21(r1)
+	mtlr	r4
+	mtcr	r5
+	/*
+	 * KVM nap requires r2 to be saved, rather than just restoring it
+	 * from PACATOC. This could be avoided for that less common case
+	 * if KVM saved its r2.
+	 */
+	ld	r2,-8*1(r1)
+	ld	r14,-8*2(r1)
+	ld	r15,-8*3(r1)
+	ld	r16,-8*4(r1)
+	ld	r17,-8*5(r1)
+	ld	r18,-8*6(r1)
+	ld	r19,-8*7(r1)
+	ld	r20,-8*8(r1)
+	ld	r21,-8*9(r1)
+	ld	r22,-8*10(r1)
+	ld	r23,-8*11(r1)
+	ld	r24,-8*12(r1)
+	ld	r25,-8*13(r1)
+	ld	r26,-8*14(r1)
+	ld	r27,-8*15(r1)
+	ld	r28,-8*16(r1)
+	ld	r29,-8*17(r1)
+	ld	r30,-8*18(r1)
+	ld	r31,-8*19(r1)
+	blr
+
+/*
+ * This is the sequence required to execute idle instructions, as
+ * specified in ISA v2.07 (and earlier). MSR[IR] and MSR[DR] must be 0.
+ * We have to store a GPR somewhere, ptesync, then reload it, and create
+ * a false dependency on the result of the load. It doesn't matter which
+ * GPR we store, or where we store it. We have already stored r2 to the
+ * stack at -8(r1) in isa206_idle_insn_mayloss, so use that.
+ */
+#define IDLE_STATE_ENTER_SEQ_NORET(IDLE_INST)			\
+	/* Magic NAP/SLEEP/WINKLE mode enter sequence */	\
+	std	r2,-8(r1);					\
+	ptesync;						\
+	ld	r2,-8(r1);					\
+236:	cmpd	cr0,r2,r2;					\
+	bne	236b;						\
+	IDLE_INST;						\
+	b	.	/* catch bugs */
+
+/*
+ * Desired instruction type in r3
+ *
+ * GPRs may be lost, so they are saved here. Wakeup is by interrupt only.
+ * The SRESET wakeup returns to this function's caller by calling
+ * idle_return_gpr_loss with r3 set to desired return value.
+ *
+ * A wakeup without GPR loss may alteratively be handled as in
+ * isa300_idle_stop_noloss and blr directly, as an optimisation.
+ *
+ * The caller is responsible for saving/restoring SPRs, MSR, timebase,
+ * etc.
+ *
+ * This must be called in real-mode (MSR_IDLE).
+ */
+_GLOBAL(isa206_idle_insn_mayloss)
+	std	r1,PACAR1(r13)
+	mflr	r4
+	mfcr	r5
+	/*
+	 * Use the stack red zone rather than a new frame for saving regs since
+	 * in the case of no GPR loss the wakeup code branches directly back to
+	 * the caller without deallocating the stack frame first.
+	 */
+	std	r2,-8*1(r1)
+	std	r14,-8*2(r1)
+	std	r15,-8*3(r1)
+	std	r16,-8*4(r1)
+	std	r17,-8*5(r1)
+	std	r18,-8*6(r1)
+	std	r19,-8*7(r1)
+	std	r20,-8*8(r1)
+	std	r21,-8*9(r1)
+	std	r22,-8*10(r1)
+	std	r23,-8*11(r1)
+	std	r24,-8*12(r1)
+	std	r25,-8*13(r1)
+	std	r26,-8*14(r1)
+	std	r27,-8*15(r1)
+	std	r28,-8*16(r1)
+	std	r29,-8*17(r1)
+	std	r30,-8*18(r1)
+	std	r31,-8*19(r1)
+	std	r4,-8*20(r1)
+	std	r5,-8*21(r1)
+	cmpwi	r3,PNV_THREAD_NAP
+	bne	1f
+	IDLE_STATE_ENTER_SEQ_NORET(PPC_NAP)
+1:	cmpwi	r3,PNV_THREAD_SLEEP
+	bne	2f
+	IDLE_STATE_ENTER_SEQ_NORET(PPC_SLEEP)
+2:	IDLE_STATE_ENTER_SEQ_NORET(PPC_WINKLE)
+#endif
+
+#ifdef CONFIG_PPC_970_NAP
+_GLOBAL(power4_idle_nap)
+	LOAD_REG_IMMEDIATE(r7, MSR_KERNEL|MSR_EE|MSR_POW)
+	ld	r9,PACA_THREAD_INFO(r13)
+	ld	r8,TI_LOCAL_FLAGS(r9)
+	ori	r8,r8,_TLF_NAPPING
+	std	r8,TI_LOCAL_FLAGS(r9)
+	/*
+	 * NAPPING bit is set, from this point onward power4_fixup_nap
+	 * will cause exceptions to return to power4_idle_nap_return.
+	 */
+1:	sync
+	isync
+	mtmsrd	r7
+	isync
+	b	1b
+
+	.globl power4_idle_nap_return
+power4_idle_nap_return:
+	blr
+#endif