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49f2ec91 RB |
1 | /* |
2 | * MIPS idle loop and WAIT instruction support. | |
3 | * | |
4 | * Copyright (C) xxxx the Anonymous | |
5 | * Copyright (C) 1994 - 2006 Ralf Baechle | |
6 | * Copyright (C) 2003, 2004 Maciej W. Rozycki | |
7 | * Copyright (C) 2001, 2004, 2011, 2012 MIPS Technologies, Inc. | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or | |
10 | * modify it under the terms of the GNU General Public License | |
11 | * as published by the Free Software Foundation; either version | |
12 | * 2 of the License, or (at your option) any later version. | |
13 | */ | |
14 | #include <linux/export.h> | |
15 | #include <linux/init.h> | |
16 | #include <linux/irqflags.h> | |
17 | #include <linux/printk.h> | |
18 | #include <linux/sched.h> | |
19 | #include <asm/cpu.h> | |
20 | #include <asm/cpu-info.h> | |
bdc92d74 | 21 | #include <asm/idle.h> |
49f2ec91 RB |
22 | #include <asm/mipsregs.h> |
23 | ||
24 | /* | |
25 | * Not all of the MIPS CPUs have the "wait" instruction available. Moreover, | |
26 | * the implementation of the "wait" feature differs between CPU families. This | |
27 | * points to the function that implements CPU specific wait. | |
28 | * The wait instruction stops the pipeline and reduces the power consumption of | |
29 | * the CPU very much. | |
30 | */ | |
31 | void (*cpu_wait)(void); | |
32 | EXPORT_SYMBOL(cpu_wait); | |
33 | ||
34 | static void r3081_wait(void) | |
35 | { | |
36 | unsigned long cfg = read_c0_conf(); | |
37 | write_c0_conf(cfg | R30XX_CONF_HALT); | |
fb40bc3e | 38 | local_irq_enable(); |
49f2ec91 RB |
39 | } |
40 | ||
41 | static void r39xx_wait(void) | |
42 | { | |
49f2ec91 RB |
43 | if (!need_resched()) |
44 | write_c0_conf(read_c0_conf() | TX39_CONF_HALT); | |
45 | local_irq_enable(); | |
46 | } | |
47 | ||
087d990b RB |
48 | void r4k_wait(void) |
49 | { | |
50 | local_irq_enable(); | |
51 | __r4k_wait(); | |
52 | } | |
53 | ||
49f2ec91 RB |
54 | /* |
55 | * This variant is preferable as it allows testing need_resched and going to | |
56 | * sleep depending on the outcome atomically. Unfortunately the "It is | |
57 | * implementation-dependent whether the pipeline restarts when a non-enabled | |
58 | * interrupt is requested" restriction in the MIPS32/MIPS64 architecture makes | |
59 | * using this version a gamble. | |
60 | */ | |
61 | void r4k_wait_irqoff(void) | |
62 | { | |
49f2ec91 | 63 | if (!need_resched()) |
f91a148a RB |
64 | __asm__( |
65 | " .set push \n" | |
66 | " .set mips3 \n" | |
67 | " wait \n" | |
68 | " .set pop \n"); | |
49f2ec91 | 69 | local_irq_enable(); |
f91a148a RB |
70 | __asm__( |
71 | " .globl __pastwait \n" | |
72 | "__pastwait: \n"); | |
49f2ec91 RB |
73 | } |
74 | ||
75 | /* | |
76 | * The RM7000 variant has to handle erratum 38. The workaround is to not | |
77 | * have any pending stores when the WAIT instruction is executed. | |
78 | */ | |
79 | static void rm7k_wait_irqoff(void) | |
80 | { | |
49f2ec91 RB |
81 | if (!need_resched()) |
82 | __asm__( | |
83 | " .set push \n" | |
84 | " .set mips3 \n" | |
85 | " .set noat \n" | |
86 | " mfc0 $1, $12 \n" | |
87 | " sync \n" | |
88 | " mtc0 $1, $12 # stalls until W stage \n" | |
89 | " wait \n" | |
90 | " mtc0 $1, $12 # stalls until W stage \n" | |
91 | " .set pop \n"); | |
92 | local_irq_enable(); | |
93 | } | |
94 | ||
95 | /* | |
96 | * The Au1xxx wait is available only if using 32khz counter or | |
97 | * external timer source, but specifically not CP0 Counter. | |
98 | * alchemy/common/time.c may override cpu_wait! | |
99 | */ | |
100 | static void au1k_wait(void) | |
101 | { | |
f91a148a RB |
102 | __asm__( |
103 | " .set mips3 \n" | |
104 | " cache 0x14, 0(%0) \n" | |
105 | " cache 0x14, 32(%0) \n" | |
106 | " sync \n" | |
107 | " nop \n" | |
108 | " wait \n" | |
109 | " nop \n" | |
110 | " nop \n" | |
111 | " nop \n" | |
112 | " nop \n" | |
113 | " .set mips0 \n" | |
114 | : : "r" (au1k_wait)); | |
fb40bc3e | 115 | local_irq_enable(); |
49f2ec91 RB |
116 | } |
117 | ||
118 | static int __initdata nowait; | |
119 | ||
120 | static int __init wait_disable(char *s) | |
121 | { | |
122 | nowait = 1; | |
123 | ||
124 | return 1; | |
125 | } | |
126 | ||
127 | __setup("nowait", wait_disable); | |
128 | ||
129 | void __init check_wait(void) | |
130 | { | |
131 | struct cpuinfo_mips *c = ¤t_cpu_data; | |
132 | ||
133 | if (nowait) { | |
134 | printk("Wait instruction disabled.\n"); | |
135 | return; | |
136 | } | |
137 | ||
138 | switch (c->cputype) { | |
139 | case CPU_R3081: | |
140 | case CPU_R3081E: | |
141 | cpu_wait = r3081_wait; | |
142 | break; | |
143 | case CPU_TX3927: | |
144 | cpu_wait = r39xx_wait; | |
145 | break; | |
146 | case CPU_R4200: | |
147 | /* case CPU_R4300: */ | |
148 | case CPU_R4600: | |
149 | case CPU_R4640: | |
150 | case CPU_R4650: | |
151 | case CPU_R4700: | |
152 | case CPU_R5000: | |
153 | case CPU_R5500: | |
154 | case CPU_NEVADA: | |
155 | case CPU_4KC: | |
156 | case CPU_4KEC: | |
157 | case CPU_4KSC: | |
158 | case CPU_5KC: | |
159 | case CPU_25KF: | |
160 | case CPU_PR4450: | |
161 | case CPU_BMIPS3300: | |
162 | case CPU_BMIPS4350: | |
163 | case CPU_BMIPS4380: | |
164 | case CPU_BMIPS5000: | |
165 | case CPU_CAVIUM_OCTEON: | |
166 | case CPU_CAVIUM_OCTEON_PLUS: | |
167 | case CPU_CAVIUM_OCTEON2: | |
168 | case CPU_JZRISC: | |
169 | case CPU_LOONGSON1: | |
170 | case CPU_XLR: | |
171 | case CPU_XLP: | |
172 | cpu_wait = r4k_wait; | |
173 | break; | |
174 | ||
175 | case CPU_RM7000: | |
176 | cpu_wait = rm7k_wait_irqoff; | |
177 | break; | |
178 | ||
179 | case CPU_M14KC: | |
180 | case CPU_M14KEC: | |
181 | case CPU_24K: | |
182 | case CPU_34K: | |
183 | case CPU_1004K: | |
184 | cpu_wait = r4k_wait; | |
185 | if (read_c0_config7() & MIPS_CONF7_WII) | |
186 | cpu_wait = r4k_wait_irqoff; | |
187 | break; | |
188 | ||
189 | case CPU_74K: | |
190 | cpu_wait = r4k_wait; | |
191 | if ((c->processor_id & 0xff) >= PRID_REV_ENCODE_332(2, 1, 0)) | |
192 | cpu_wait = r4k_wait_irqoff; | |
193 | break; | |
194 | ||
195 | case CPU_TX49XX: | |
196 | cpu_wait = r4k_wait_irqoff; | |
197 | break; | |
198 | case CPU_ALCHEMY: | |
199 | cpu_wait = au1k_wait; | |
200 | break; | |
201 | case CPU_20KC: | |
202 | /* | |
203 | * WAIT on Rev1.0 has E1, E2, E3 and E16. | |
204 | * WAIT on Rev2.0 and Rev3.0 has E16. | |
205 | * Rev3.1 WAIT is nop, why bother | |
206 | */ | |
207 | if ((c->processor_id & 0xff) <= 0x64) | |
208 | break; | |
209 | ||
210 | /* | |
211 | * Another rev is incremeting c0_count at a reduced clock | |
212 | * rate while in WAIT mode. So we basically have the choice | |
213 | * between using the cp0 timer as clocksource or avoiding | |
214 | * the WAIT instruction. Until more details are known, | |
215 | * disable the use of WAIT for 20Kc entirely. | |
216 | cpu_wait = r4k_wait; | |
217 | */ | |
218 | break; | |
219 | case CPU_RM9000: | |
220 | if ((c->processor_id & 0x00ff) >= 0x40) | |
221 | cpu_wait = r4k_wait; | |
222 | break; | |
223 | default: | |
224 | break; | |
225 | } | |
226 | } | |
227 | ||
00baf857 | 228 | static void smtc_idle_hook(void) |
49f2ec91 RB |
229 | { |
230 | #ifdef CONFIG_MIPS_MT_SMTC | |
00baf857 | 231 | void smtc_idle_loop_hook(void); |
49f2ec91 RB |
232 | |
233 | smtc_idle_loop_hook(); | |
234 | #endif | |
00baf857 RB |
235 | } |
236 | ||
237 | void arch_cpu_idle(void) | |
238 | { | |
239 | smtc_idle_hook(); | |
49f2ec91 | 240 | if (cpu_wait) |
c9b6869d | 241 | cpu_wait(); |
49f2ec91 RB |
242 | else |
243 | local_irq_enable(); | |
244 | } |