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Diffstat (limited to 'arch/powerpc/kernel/idle_book3s.S')
-rw-r--r-- | arch/powerpc/kernel/idle_book3s.S | 218 |
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 0000000000..3d97fb8338 --- /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 |