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#include <asm/thread_info.h> /* TLF_NAPPING */
 19
 20#ifdef CONFIG_PPC_P7_NAP
 21/*
 22 * Desired PSSCR in r3
 23 *
 24 * No state will be lost regardless of wakeup mechanism (interrupt or NIA).
 25 *
 26 * An EC=0 type wakeup will return with a value of 0. SRESET wakeup (which can
 27 * happen with xscom SRESET and possibly MCE) may clobber volatiles except LR,
 28 * and must blr, to return to caller with r3 set according to caller's expected
 29 * return code (for Book3S/64 that is SRR1).
 30 */
 31_GLOBAL(isa300_idle_stop_noloss)
 32	mtspr 	SPRN_PSSCR,r3
 33	PPC_STOP
 34	li	r3,0
 35	blr
 36
 37/*
 38 * Desired PSSCR in r3
 39 *
 40 * GPRs may be lost, so they are saved here. Wakeup is by interrupt only.
 41 * The SRESET wakeup returns to this function's caller by calling
 42 * idle_return_gpr_loss with r3 set to desired return value.
 43 *
 44 * A wakeup without GPR loss may alteratively be handled as in
 45 * isa300_idle_stop_noloss and blr directly, as an optimisation.
 46 *
 47 * The caller is responsible for saving/restoring SPRs, MSR, timebase,
 48 * etc.
 49 */
 50_GLOBAL(isa300_idle_stop_mayloss)
 51	mtspr 	SPRN_PSSCR,r3
 52	std	r1,PACAR1(r13)
 53	mflr	r4
 54	mfcr	r5
 55	/* use stack red zone rather than a new frame for saving regs */
 56	std	r2,-8*0(r1)
 57	std	r14,-8*1(r1)
 58	std	r15,-8*2(r1)
 59	std	r16,-8*3(r1)
 60	std	r17,-8*4(r1)
 61	std	r18,-8*5(r1)
 62	std	r19,-8*6(r1)
 63	std	r20,-8*7(r1)
 64	std	r21,-8*8(r1)
 65	std	r22,-8*9(r1)
 66	std	r23,-8*10(r1)
 67	std	r24,-8*11(r1)
 68	std	r25,-8*12(r1)
 69	std	r26,-8*13(r1)
 70	std	r27,-8*14(r1)
 71	std	r28,-8*15(r1)
 72	std	r29,-8*16(r1)
 73	std	r30,-8*17(r1)
 74	std	r31,-8*18(r1)
 75	std	r4,-8*19(r1)
 76	std	r5,-8*20(r1)
 77	/* 168 bytes */
 78	PPC_STOP
 79	b	.	/* catch bugs */
 80
 81/*
 82 * Desired return value in r3
 83 *
 84 * The idle wakeup SRESET interrupt can call this after calling
 85 * to return to the idle sleep function caller with r3 as the return code.
 86 *
 87 * This must not be used if idle was entered via a _noloss function (use
 88 * a simple blr instead).
 89 */
 90_GLOBAL(idle_return_gpr_loss)
 91	ld	r1,PACAR1(r13)
 92	ld	r4,-8*19(r1)
 93	ld	r5,-8*20(r1)
 94	mtlr	r4
 95	mtcr	r5
 96	/*
 97	 * KVM nap requires r2 to be saved, rather than just restoring it
 98	 * from PACATOC. This could be avoided for that less common case
 99	 * if KVM saved its r2.
100	 */
101	ld	r2,-8*0(r1)
102	ld	r14,-8*1(r1)
103	ld	r15,-8*2(r1)
104	ld	r16,-8*3(r1)
105	ld	r17,-8*4(r1)
106	ld	r18,-8*5(r1)
107	ld	r19,-8*6(r1)
108	ld	r20,-8*7(r1)
109	ld	r21,-8*8(r1)
110	ld	r22,-8*9(r1)
111	ld	r23,-8*10(r1)
112	ld	r24,-8*11(r1)
113	ld	r25,-8*12(r1)
114	ld	r26,-8*13(r1)
115	ld	r27,-8*14(r1)
116	ld	r28,-8*15(r1)
117	ld	r29,-8*16(r1)
118	ld	r30,-8*17(r1)
119	ld	r31,-8*18(r1)
120	blr
121
122/*
123 * This is the sequence required to execute idle instructions, as
124 * specified in ISA v2.07 (and earlier). MSR[IR] and MSR[DR] must be 0.
125 *
126 * The 0(r1) slot is used to save r2 in isa206, so use that here.
127 */
128#define IDLE_STATE_ENTER_SEQ_NORET(IDLE_INST)			\
129	/* Magic NAP/SLEEP/WINKLE mode enter sequence */	\
130	std	r2,0(r1);					\
131	ptesync;						\
132	ld	r2,0(r1);					\
133236:	cmpd	cr0,r2,r2;					\
134	bne	236b;						\
135	IDLE_INST;						\
136	b	.	/* catch bugs */
137
138/*
139 * Desired instruction type in r3
140 *
141 * GPRs may be lost, so they are saved here. Wakeup is by interrupt only.
142 * The SRESET wakeup returns to this function's caller by calling
143 * idle_return_gpr_loss with r3 set to desired return value.
144 *
145 * A wakeup without GPR loss may alteratively be handled as in
146 * isa300_idle_stop_noloss and blr directly, as an optimisation.
147 *
148 * The caller is responsible for saving/restoring SPRs, MSR, timebase,
149 * etc.
150 *
151 * This must be called in real-mode (MSR_IDLE).
152 */
153_GLOBAL(isa206_idle_insn_mayloss)
154	std	r1,PACAR1(r13)
155	mflr	r4
156	mfcr	r5
157	/* use stack red zone rather than a new frame for saving regs */
158	std	r2,-8*0(r1)
159	std	r14,-8*1(r1)
160	std	r15,-8*2(r1)
161	std	r16,-8*3(r1)
162	std	r17,-8*4(r1)
163	std	r18,-8*5(r1)
164	std	r19,-8*6(r1)
165	std	r20,-8*7(r1)
166	std	r21,-8*8(r1)
167	std	r22,-8*9(r1)
168	std	r23,-8*10(r1)
169	std	r24,-8*11(r1)
170	std	r25,-8*12(r1)
171	std	r26,-8*13(r1)
172	std	r27,-8*14(r1)
173	std	r28,-8*15(r1)
174	std	r29,-8*16(r1)
175	std	r30,-8*17(r1)
176	std	r31,-8*18(r1)
177	std	r4,-8*19(r1)
178	std	r5,-8*20(r1)
179	cmpwi	r3,PNV_THREAD_NAP
180	bne	1f
181	IDLE_STATE_ENTER_SEQ_NORET(PPC_NAP)
1821:	cmpwi	r3,PNV_THREAD_SLEEP
183	bne	2f
184	IDLE_STATE_ENTER_SEQ_NORET(PPC_SLEEP)
1852:	IDLE_STATE_ENTER_SEQ_NORET(PPC_WINKLE)
186#endif
187
188#ifdef CONFIG_PPC_970_NAP
189_GLOBAL(power4_idle_nap)
190	LOAD_REG_IMMEDIATE(r7, MSR_KERNEL|MSR_EE|MSR_POW)
191	ld	r9,PACA_THREAD_INFO(r13)
192	ld	r8,TI_LOCAL_FLAGS(r9)
193	ori	r8,r8,_TLF_NAPPING
194	std	r8,TI_LOCAL_FLAGS(r9)
195	/*
196	 * NAPPING bit is set, from this point onward power4_fixup_nap
197	 * will cause exceptions to return to power4_idle_nap_return.
198	 */
1991:	sync
200	isync
201	mtmsrd	r7
202	isync
203	b	1b
204#endif