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