1/* SPDX-License-Identifier: GPL-2.0-or-later */ 2/* 3 * Copyright 2018, IBM Corporation. 4 * 5 * This file contains general idle entry/exit functions to save 6 * and restore stack and NVGPRs which allows C code to call idle 7 * states that lose GPRs, and it will return transparently with 8 * SRR1 wakeup reason return value. 9 * 10 * The platform / CPU caller must ensure SPRs and any other non-GPR 11 * state is saved and restored correctly, handle KVM, interrupts, etc. 12 */ 13 14#include <asm/ppc_asm.h> 15#include <asm/asm-offsets.h> 16#include <asm/ppc-opcode.h> 17#include <asm/cpuidle.h> 18 19/* 20 * Desired PSSCR in r3 21 * 22 * No state will be lost regardless of wakeup mechanism (interrupt or NIA). 23 * 24 * An EC=0 type wakeup will return with a value of 0. SRESET wakeup (which can 25 * happen with xscom SRESET and possibly MCE) may clobber volatiles except LR, 26 * and must blr, to return to caller with r3 set according to caller's expected 27 * return code (for Book3S/64 that is SRR1). 28 */ 29_GLOBAL(isa300_idle_stop_noloss) 30 mtspr SPRN_PSSCR,r3 31 PPC_STOP 32 li r3,0 33 blr 34 35/* 36 * Desired PSSCR in r3 37 * 38 * GPRs may be lost, so they are saved here. Wakeup is by interrupt only. 39 * The SRESET wakeup returns to this function's caller by calling 40 * idle_return_gpr_loss with r3 set to desired return value. 41 * 42 * A wakeup without GPR loss may alteratively be handled as in 43 * isa300_idle_stop_noloss and blr directly, as an optimisation. 44 * 45 * The caller is responsible for saving/restoring SPRs, MSR, timebase, 46 * etc. 47 */ 48_GLOBAL(isa300_idle_stop_mayloss) 49 mtspr SPRN_PSSCR,r3 50 std r1,PACAR1(r13) 51 mflr r4 52 mfcr r5 53 /* use stack red zone rather than a new frame for saving regs */ 54 std r2,-8*0(r1) 55 std r14,-8*1(r1) 56 std r15,-8*2(r1) 57 std r16,-8*3(r1) 58 std r17,-8*4(r1) 59 std r18,-8*5(r1) 60 std r19,-8*6(r1) 61 std r20,-8*7(r1) 62 std r21,-8*8(r1) 63 std r22,-8*9(r1) 64 std r23,-8*10(r1) 65 std r24,-8*11(r1) 66 std r25,-8*12(r1) 67 std r26,-8*13(r1) 68 std r27,-8*14(r1) 69 std r28,-8*15(r1) 70 std r29,-8*16(r1) 71 std r30,-8*17(r1) 72 std r31,-8*18(r1) 73 std r4,-8*19(r1) 74 std r5,-8*20(r1) 75 /* 168 bytes */ 76 PPC_STOP 77 b . /* catch bugs */ 78 79/* 80 * Desired return value in r3 81 * 82 * The idle wakeup SRESET interrupt can call this after calling 83 * to return to the idle sleep function caller with r3 as the return code. 84 * 85 * This must not be used if idle was entered via a _noloss function (use 86 * a simple blr instead). 87 */ 88_GLOBAL(idle_return_gpr_loss) 89 ld r1,PACAR1(r13) 90 ld r4,-8*19(r1) 91 ld r5,-8*20(r1) 92 mtlr r4 93 mtcr r5 94 /* 95 * KVM nap requires r2 to be saved, rather than just restoring it 96 * from PACATOC. This could be avoided for that less common case 97 * if KVM saved its r2. 98 */ 99 ld r2,-8*0(r1) 100 ld r14,-8*1(r1) 101 ld r15,-8*2(r1) 102 ld r16,-8*3(r1) 103 ld r17,-8*4(r1) 104 ld r18,-8*5(r1) 105 ld r19,-8*6(r1) 106 ld r20,-8*7(r1) 107 ld r21,-8*8(r1) 108 ld r22,-8*9(r1) 109 ld r23,-8*10(r1) 110 ld r24,-8*11(r1) 111 ld r25,-8*12(r1) 112 ld r26,-8*13(r1) 113 ld r27,-8*14(r1) 114 ld r28,-8*15(r1) 115 ld r29,-8*16(r1) 116 ld r30,-8*17(r1) 117 ld r31,-8*18(r1) 118 blr 119 120/* 121 * This is the sequence required to execute idle instructions, as 122 * specified in ISA v2.07 (and earlier). MSR[IR] and MSR[DR] must be 0. 123 * 124 * The 0(r1) slot is used to save r2 in isa206, so use that here. 125 */ 126#define IDLE_STATE_ENTER_SEQ_NORET(IDLE_INST) \ 127 /* Magic NAP/SLEEP/WINKLE mode enter sequence */ \ 128 std r2,0(r1); \ 129 ptesync; \ 130 ld r2,0(r1); \ 131236: cmpd cr0,r2,r2; \ 132 bne 236b; \ 133 IDLE_INST; \ 134 b . /* catch bugs */ 135 136/* 137 * Desired instruction type in r3 138 * 139 * GPRs may be lost, so they are saved here. Wakeup is by interrupt only. 140 * The SRESET wakeup returns to this function's caller by calling 141 * idle_return_gpr_loss with r3 set to desired return value. 142 * 143 * A wakeup without GPR loss may alteratively be handled as in 144 * isa300_idle_stop_noloss and blr directly, as an optimisation. 145 * 146 * The caller is responsible for saving/restoring SPRs, MSR, timebase, 147 * etc. 148 * 149 * This must be called in real-mode (MSR_IDLE). 150 */ 151_GLOBAL(isa206_idle_insn_mayloss) 152 std r1,PACAR1(r13) 153 mflr r4 154 mfcr r5 155 /* use stack red zone rather than a new frame for saving regs */ 156 std r2,-8*0(r1) 157 std r14,-8*1(r1) 158 std r15,-8*2(r1) 159 std r16,-8*3(r1) 160 std r17,-8*4(r1) 161 std r18,-8*5(r1) 162 std r19,-8*6(r1) 163 std r20,-8*7(r1) 164 std r21,-8*8(r1) 165 std r22,-8*9(r1) 166 std r23,-8*10(r1) 167 std r24,-8*11(r1) 168 std r25,-8*12(r1) 169 std r26,-8*13(r1) 170 std r27,-8*14(r1) 171 std r28,-8*15(r1) 172 std r29,-8*16(r1) 173 std r30,-8*17(r1) 174 std r31,-8*18(r1) 175 std r4,-8*19(r1) 176 std r5,-8*20(r1) 177 cmpwi r3,PNV_THREAD_NAP 178 bne 1f 179 IDLE_STATE_ENTER_SEQ_NORET(PPC_NAP) 1801: cmpwi r3,PNV_THREAD_SLEEP 181 bne 2f 182 IDLE_STATE_ENTER_SEQ_NORET(PPC_SLEEP) 1832: IDLE_STATE_ENTER_SEQ_NORET(PPC_WINKLE) 184 185