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1da177e4 LT |
1 | /* |
2 | * Idle daemon for PowerPC. Idle daemon will handle any action | |
3 | * that needs to be taken when the system becomes idle. | |
4 | * | |
5 | * Originally Written by Cort Dougan (cort@cs.nmt.edu) | |
6 | * | |
7 | * iSeries supported added by Mike Corrigan <mikejc@us.ibm.com> | |
8 | * | |
9 | * Additional shared processor, SMT, and firmware support | |
10 | * Copyright (c) 2003 Dave Engebretsen <engebret@us.ibm.com> | |
11 | * | |
12 | * This program is free software; you can redistribute it and/or | |
13 | * modify it under the terms of the GNU General Public License | |
14 | * as published by the Free Software Foundation; either version | |
15 | * 2 of the License, or (at your option) any later version. | |
16 | */ | |
17 | ||
18 | #include <linux/config.h> | |
19 | #include <linux/sched.h> | |
20 | #include <linux/kernel.h> | |
21 | #include <linux/smp.h> | |
22 | #include <linux/cpu.h> | |
23 | #include <linux/module.h> | |
24 | #include <linux/sysctl.h> | |
25 | #include <linux/smp.h> | |
26 | ||
27 | #include <asm/system.h> | |
28 | #include <asm/processor.h> | |
29 | #include <asm/mmu.h> | |
30 | #include <asm/cputable.h> | |
31 | #include <asm/time.h> | |
32 | #include <asm/iSeries/HvCall.h> | |
33 | #include <asm/iSeries/ItLpQueue.h> | |
34 | #include <asm/plpar_wrappers.h> | |
35 | #include <asm/systemcfg.h> | |
36 | ||
37 | extern void power4_idle(void); | |
38 | ||
39 | static int (*idle_loop)(void); | |
40 | ||
41 | #ifdef CONFIG_PPC_ISERIES | |
42 | static unsigned long maxYieldTime = 0; | |
43 | static unsigned long minYieldTime = 0xffffffffffffffffUL; | |
44 | ||
c92877e0 SR |
45 | static inline void process_iSeries_events(void) |
46 | { | |
47 | asm volatile ("li 0,0x5555; sc" : : : "r0", "r3"); | |
48 | } | |
49 | ||
1da177e4 LT |
50 | static void yield_shared_processor(void) |
51 | { | |
52 | unsigned long tb; | |
53 | unsigned long yieldTime; | |
54 | ||
55 | HvCall_setEnabledInterrupts(HvCall_MaskIPI | | |
56 | HvCall_MaskLpEvent | | |
57 | HvCall_MaskLpProd | | |
58 | HvCall_MaskTimeout); | |
59 | ||
60 | tb = get_tb(); | |
61 | /* Compute future tb value when yield should expire */ | |
62 | HvCall_yieldProcessor(HvCall_YieldTimed, tb+tb_ticks_per_jiffy); | |
63 | ||
64 | yieldTime = get_tb() - tb; | |
65 | if (yieldTime > maxYieldTime) | |
66 | maxYieldTime = yieldTime; | |
67 | ||
68 | if (yieldTime < minYieldTime) | |
69 | minYieldTime = yieldTime; | |
70 | ||
71 | /* | |
72 | * The decrementer stops during the yield. Force a fake decrementer | |
73 | * here and let the timer_interrupt code sort out the actual time. | |
74 | */ | |
75 | get_paca()->lppaca.int_dword.fields.decr_int = 1; | |
76 | process_iSeries_events(); | |
77 | } | |
78 | ||
79 | static int iSeries_idle(void) | |
80 | { | |
81 | struct paca_struct *lpaca; | |
82 | long oldval; | |
1da177e4 LT |
83 | |
84 | /* ensure iSeries run light will be out when idle */ | |
6dc2f0c7 | 85 | ppc64_runlatch_off(); |
1da177e4 LT |
86 | |
87 | lpaca = get_paca(); | |
88 | ||
89 | while (1) { | |
90 | if (lpaca->lppaca.shared_proc) { | |
937b31b1 | 91 | if (hvlpevent_is_pending()) |
1da177e4 LT |
92 | process_iSeries_events(); |
93 | if (!need_resched()) | |
94 | yield_shared_processor(); | |
95 | } else { | |
96 | oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED); | |
97 | ||
98 | if (!oldval) { | |
99 | set_thread_flag(TIF_POLLING_NRFLAG); | |
100 | ||
101 | while (!need_resched()) { | |
102 | HMT_medium(); | |
937b31b1 | 103 | if (hvlpevent_is_pending()) |
1da177e4 LT |
104 | process_iSeries_events(); |
105 | HMT_low(); | |
106 | } | |
107 | ||
108 | HMT_medium(); | |
109 | clear_thread_flag(TIF_POLLING_NRFLAG); | |
110 | } else { | |
111 | set_need_resched(); | |
112 | } | |
113 | } | |
114 | ||
6dc2f0c7 | 115 | ppc64_runlatch_on(); |
1da177e4 | 116 | schedule(); |
6dc2f0c7 | 117 | ppc64_runlatch_off(); |
1da177e4 LT |
118 | } |
119 | ||
120 | return 0; | |
121 | } | |
122 | ||
123 | #else | |
124 | ||
125 | static int default_idle(void) | |
126 | { | |
127 | long oldval; | |
128 | unsigned int cpu = smp_processor_id(); | |
129 | ||
130 | while (1) { | |
131 | oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED); | |
132 | ||
133 | if (!oldval) { | |
134 | set_thread_flag(TIF_POLLING_NRFLAG); | |
135 | ||
136 | while (!need_resched() && !cpu_is_offline(cpu)) { | |
137 | barrier(); | |
138 | /* | |
139 | * Go into low thread priority and possibly | |
140 | * low power mode. | |
141 | */ | |
142 | HMT_low(); | |
143 | HMT_very_low(); | |
144 | } | |
145 | ||
146 | HMT_medium(); | |
147 | clear_thread_flag(TIF_POLLING_NRFLAG); | |
148 | } else { | |
149 | set_need_resched(); | |
150 | } | |
151 | ||
152 | schedule(); | |
153 | if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING) | |
154 | cpu_die(); | |
155 | } | |
156 | ||
157 | return 0; | |
158 | } | |
159 | ||
160 | #ifdef CONFIG_PPC_PSERIES | |
161 | ||
162 | DECLARE_PER_CPU(unsigned long, smt_snooze_delay); | |
163 | ||
164 | int dedicated_idle(void) | |
165 | { | |
166 | long oldval; | |
167 | struct paca_struct *lpaca = get_paca(), *ppaca; | |
168 | unsigned long start_snooze; | |
169 | unsigned long *smt_snooze_delay = &__get_cpu_var(smt_snooze_delay); | |
170 | unsigned int cpu = smp_processor_id(); | |
171 | ||
172 | ppaca = &paca[cpu ^ 1]; | |
173 | ||
174 | while (1) { | |
175 | /* | |
176 | * Indicate to the HV that we are idle. Now would be | |
177 | * a good time to find other work to dispatch. | |
178 | */ | |
179 | lpaca->lppaca.idle = 1; | |
180 | ||
181 | oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED); | |
182 | if (!oldval) { | |
183 | set_thread_flag(TIF_POLLING_NRFLAG); | |
184 | start_snooze = __get_tb() + | |
185 | *smt_snooze_delay * tb_ticks_per_usec; | |
186 | while (!need_resched() && !cpu_is_offline(cpu)) { | |
187 | /* | |
188 | * Go into low thread priority and possibly | |
189 | * low power mode. | |
190 | */ | |
191 | HMT_low(); | |
192 | HMT_very_low(); | |
193 | ||
194 | if (*smt_snooze_delay == 0 || | |
195 | __get_tb() < start_snooze) | |
196 | continue; | |
197 | ||
198 | HMT_medium(); | |
199 | ||
200 | if (!(ppaca->lppaca.idle)) { | |
201 | local_irq_disable(); | |
202 | ||
203 | /* | |
204 | * We are about to sleep the thread | |
205 | * and so wont be polling any | |
206 | * more. | |
207 | */ | |
208 | clear_thread_flag(TIF_POLLING_NRFLAG); | |
209 | ||
210 | /* | |
211 | * SMT dynamic mode. Cede will result | |
212 | * in this thread going dormant, if the | |
213 | * partner thread is still doing work. | |
214 | * Thread wakes up if partner goes idle, | |
215 | * an interrupt is presented, or a prod | |
216 | * occurs. Returning from the cede | |
217 | * enables external interrupts. | |
218 | */ | |
219 | if (!need_resched()) | |
220 | cede_processor(); | |
221 | else | |
222 | local_irq_enable(); | |
223 | } else { | |
224 | /* | |
225 | * Give the HV an opportunity at the | |
226 | * processor, since we are not doing | |
227 | * any work. | |
228 | */ | |
229 | poll_pending(); | |
230 | } | |
231 | } | |
232 | ||
233 | clear_thread_flag(TIF_POLLING_NRFLAG); | |
234 | } else { | |
235 | set_need_resched(); | |
236 | } | |
237 | ||
238 | HMT_medium(); | |
239 | lpaca->lppaca.idle = 0; | |
240 | schedule(); | |
241 | if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING) | |
242 | cpu_die(); | |
243 | } | |
244 | return 0; | |
245 | } | |
246 | ||
247 | static int shared_idle(void) | |
248 | { | |
249 | struct paca_struct *lpaca = get_paca(); | |
250 | unsigned int cpu = smp_processor_id(); | |
251 | ||
252 | while (1) { | |
253 | /* | |
254 | * Indicate to the HV that we are idle. Now would be | |
255 | * a good time to find other work to dispatch. | |
256 | */ | |
257 | lpaca->lppaca.idle = 1; | |
258 | ||
259 | while (!need_resched() && !cpu_is_offline(cpu)) { | |
260 | local_irq_disable(); | |
261 | ||
262 | /* | |
263 | * Yield the processor to the hypervisor. We return if | |
264 | * an external interrupt occurs (which are driven prior | |
265 | * to returning here) or if a prod occurs from another | |
266 | * processor. When returning here, external interrupts | |
267 | * are enabled. | |
268 | * | |
269 | * Check need_resched() again with interrupts disabled | |
270 | * to avoid a race. | |
271 | */ | |
272 | if (!need_resched()) | |
273 | cede_processor(); | |
274 | else | |
275 | local_irq_enable(); | |
276 | } | |
277 | ||
278 | HMT_medium(); | |
279 | lpaca->lppaca.idle = 0; | |
280 | schedule(); | |
281 | if (cpu_is_offline(smp_processor_id()) && | |
282 | system_state == SYSTEM_RUNNING) | |
283 | cpu_die(); | |
284 | } | |
285 | ||
286 | return 0; | |
287 | } | |
288 | ||
289 | #endif /* CONFIG_PPC_PSERIES */ | |
290 | ||
291 | static int native_idle(void) | |
292 | { | |
293 | while(1) { | |
294 | /* check CPU type here */ | |
295 | if (!need_resched()) | |
296 | power4_idle(); | |
297 | if (need_resched()) | |
298 | schedule(); | |
299 | ||
39c715b7 | 300 | if (cpu_is_offline(raw_smp_processor_id()) && |
1da177e4 LT |
301 | system_state == SYSTEM_RUNNING) |
302 | cpu_die(); | |
303 | } | |
304 | return 0; | |
305 | } | |
306 | ||
307 | #endif /* CONFIG_PPC_ISERIES */ | |
308 | ||
309 | void cpu_idle(void) | |
310 | { | |
311 | idle_loop(); | |
312 | } | |
313 | ||
314 | int powersave_nap; | |
315 | ||
316 | #ifdef CONFIG_SYSCTL | |
317 | /* | |
318 | * Register the sysctl to set/clear powersave_nap. | |
319 | */ | |
320 | static ctl_table powersave_nap_ctl_table[]={ | |
321 | { | |
322 | .ctl_name = KERN_PPC_POWERSAVE_NAP, | |
323 | .procname = "powersave-nap", | |
324 | .data = &powersave_nap, | |
325 | .maxlen = sizeof(int), | |
326 | .mode = 0644, | |
327 | .proc_handler = &proc_dointvec, | |
328 | }, | |
329 | { 0, }, | |
330 | }; | |
331 | static ctl_table powersave_nap_sysctl_root[] = { | |
332 | { 1, "kernel", NULL, 0, 0755, powersave_nap_ctl_table, }, | |
333 | { 0,}, | |
334 | }; | |
335 | ||
336 | static int __init | |
337 | register_powersave_nap_sysctl(void) | |
338 | { | |
339 | register_sysctl_table(powersave_nap_sysctl_root, 0); | |
340 | ||
341 | return 0; | |
342 | } | |
343 | __initcall(register_powersave_nap_sysctl); | |
344 | #endif | |
345 | ||
346 | int idle_setup(void) | |
347 | { | |
348 | /* | |
349 | * Move that junk to each platform specific file, eventually define | |
350 | * a pSeries_idle for shared processor stuff | |
351 | */ | |
352 | #ifdef CONFIG_PPC_ISERIES | |
353 | idle_loop = iSeries_idle; | |
354 | return 1; | |
355 | #else | |
356 | idle_loop = default_idle; | |
357 | #endif | |
358 | #ifdef CONFIG_PPC_PSERIES | |
359 | if (systemcfg->platform & PLATFORM_PSERIES) { | |
360 | if (cur_cpu_spec->firmware_features & FW_FEATURE_SPLPAR) { | |
361 | if (get_paca()->lppaca.shared_proc) { | |
362 | printk(KERN_INFO "Using shared processor idle loop\n"); | |
363 | idle_loop = shared_idle; | |
364 | } else { | |
365 | printk(KERN_INFO "Using dedicated idle loop\n"); | |
366 | idle_loop = dedicated_idle; | |
367 | } | |
368 | } else { | |
369 | printk(KERN_INFO "Using default idle loop\n"); | |
370 | idle_loop = default_idle; | |
371 | } | |
372 | } | |
373 | #endif /* CONFIG_PPC_PSERIES */ | |
374 | #ifndef CONFIG_PPC_ISERIES | |
375 | if (systemcfg->platform == PLATFORM_POWERMAC || | |
376 | systemcfg->platform == PLATFORM_MAPLE) { | |
377 | printk(KERN_INFO "Using native/NAP idle loop\n"); | |
378 | idle_loop = native_idle; | |
379 | } | |
380 | #endif /* CONFIG_PPC_ISERIES */ | |
381 | ||
382 | return 1; | |
383 | } |