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+/* 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