summaryrefslogtreecommitdiffstats
path: root/arch/ppc64/kernel/idle.c
blob: 6abc621d3ba0ca1fd2f52b934d83faaae4d8d81e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
/*
 * Idle daemon for PowerPC.  Idle daemon will handle any action
 * that needs to be taken when the system becomes idle.
 *
 * Originally Written by Cort Dougan (cort@cs.nmt.edu)
 *
 * iSeries supported added by Mike Corrigan <mikejc@us.ibm.com>
 *
 * Additional shared processor, SMT, and firmware support
 *    Copyright (c) 2003 Dave Engebretsen <engebret@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/config.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/smp.h>
#include <linux/cpu.h>
#include <linux/module.h>
#include <linux/sysctl.h>
#include <linux/smp.h>

#include <asm/system.h>
#include <asm/processor.h>
#include <asm/mmu.h>
#include <asm/cputable.h>
#include <asm/time.h>
#include <asm/iSeries/HvCall.h>
#include <asm/iSeries/ItLpQueue.h>
#include <asm/plpar_wrappers.h>
#include <asm/systemcfg.h>

extern void power4_idle(void);

static int (*idle_loop)(void);

#ifdef CONFIG_PPC_ISERIES
static unsigned long maxYieldTime = 0;
static unsigned long minYieldTime = 0xffffffffffffffffUL;

static void yield_shared_processor(void)
{
	unsigned long tb;
	unsigned long yieldTime;

	HvCall_setEnabledInterrupts(HvCall_MaskIPI |
				    HvCall_MaskLpEvent |
				    HvCall_MaskLpProd |
				    HvCall_MaskTimeout);

	tb = get_tb();
	/* Compute future tb value when yield should expire */
	HvCall_yieldProcessor(HvCall_YieldTimed, tb+tb_ticks_per_jiffy);

	yieldTime = get_tb() - tb;
	if (yieldTime > maxYieldTime)
		maxYieldTime = yieldTime;

	if (yieldTime < minYieldTime)
		minYieldTime = yieldTime;
	
	/*
	 * The decrementer stops during the yield.  Force a fake decrementer
	 * here and let the timer_interrupt code sort out the actual time.
	 */
	get_paca()->lppaca.int_dword.fields.decr_int = 1;
	process_iSeries_events();
}

static int iSeries_idle(void)
{
	struct paca_struct *lpaca;
	long oldval;
	unsigned long CTRL;

	/* ensure iSeries run light will be out when idle */
	clear_thread_flag(TIF_RUN_LIGHT);
	CTRL = mfspr(CTRLF);
	CTRL &= ~RUNLATCH;
	mtspr(CTRLT, CTRL);

	lpaca = get_paca();

	while (1) {
		if (lpaca->lppaca.shared_proc) {
			if (ItLpQueue_isLpIntPending(lpaca->lpqueue_ptr))
				process_iSeries_events();
			if (!need_resched())
				yield_shared_processor();
		} else {
			oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);

			if (!oldval) {
				set_thread_flag(TIF_POLLING_NRFLAG);

				while (!need_resched()) {
					HMT_medium();
					if (ItLpQueue_isLpIntPending(lpaca->lpqueue_ptr))
						process_iSeries_events();
					HMT_low();
				}

				HMT_medium();
				clear_thread_flag(TIF_POLLING_NRFLAG);
			} else {
				set_need_resched();
			}
		}

		schedule();
	}

	return 0;
}

#else

static int default_idle(void)
{
	long oldval;
	unsigned int cpu = smp_processor_id();

	while (1) {
		oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);

		if (!oldval) {
			set_thread_flag(TIF_POLLING_NRFLAG);

			while (!need_resched() && !cpu_is_offline(cpu)) {
				barrier();
				/*
				 * Go into low thread priority and possibly
				 * low power mode.
				 */
				HMT_low();
				HMT_very_low();
			}

			HMT_medium();
			clear_thread_flag(TIF_POLLING_NRFLAG);
		} else {
			set_need_resched();
		}

		schedule();
		if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
			cpu_die();
	}

	return 0;
}

#ifdef CONFIG_PPC_PSERIES

DECLARE_PER_CPU(unsigned long, smt_snooze_delay);

int dedicated_idle(void)
{
	long oldval;
	struct paca_struct *lpaca = get_paca(), *ppaca;
	unsigned long start_snooze;
	unsigned long *smt_snooze_delay = &__get_cpu_var(smt_snooze_delay);
	unsigned int cpu = smp_processor_id();

	ppaca = &paca[cpu ^ 1];

	while (1) {
		/*
		 * Indicate to the HV that we are idle. Now would be
		 * a good time to find other work to dispatch.
		 */
		lpaca->lppaca.idle = 1;

		oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
		if (!oldval) {
			set_thread_flag(TIF_POLLING_NRFLAG);
			start_snooze = __get_tb() +
				*smt_snooze_delay * tb_ticks_per_usec;
			while (!need_resched() && !cpu_is_offline(cpu)) {
				/*
				 * Go into low thread priority and possibly
				 * low power mode.
				 */
				HMT_low();
				HMT_very_low();

				if (*smt_snooze_delay == 0 ||
				    __get_tb() < start_snooze)
					continue;

				HMT_medium();

				if (!(ppaca->lppaca.idle)) {
					local_irq_disable();

					/*
					 * We are about to sleep the thread
					 * and so wont be polling any
					 * more.
					 */
					clear_thread_flag(TIF_POLLING_NRFLAG);

					/*
					 * SMT dynamic mode. Cede will result
					 * in this thread going dormant, if the
					 * partner thread is still doing work.
					 * Thread wakes up if partner goes idle,
					 * an interrupt is presented, or a prod
					 * occurs.  Returning from the cede
					 * enables external interrupts.
					 */
					if (!need_resched())
						cede_processor();
					else
						local_irq_enable();
				} else {
					/*
					 * Give the HV an opportunity at the
					 * processor, since we are not doing
					 * any work.
					 */
					poll_pending();
				}
			}

			clear_thread_flag(TIF_POLLING_NRFLAG);
		} else {
			set_need_resched();
		}

		HMT_medium();
		lpaca->lppaca.idle = 0;
		schedule();
		if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
			cpu_die();
	}
	return 0;
}

static int shared_idle(void)
{
	struct paca_struct *lpaca = get_paca();
	unsigned int cpu = smp_processor_id();

	while (1) {
		/*
		 * Indicate to the HV that we are idle. Now would be
		 * a good time to find other work to dispatch.
		 */
		lpaca->lppaca.idle = 1;

		while (!need_resched() && !cpu_is_offline(cpu)) {
			local_irq_disable();

			/*
			 * Yield the processor to the hypervisor.  We return if
			 * an external interrupt occurs (which are driven prior
			 * to returning here) or if a prod occurs from another 
			 * processor. When returning here, external interrupts
			 * are enabled.
			 *
			 * Check need_resched() again with interrupts disabled
			 * to avoid a race.
			 */
			if (!need_resched())
				cede_processor();
			else
				local_irq_enable();
		}

		HMT_medium();
		lpaca->lppaca.idle = 0;
		schedule();
		if (cpu_is_offline(smp_processor_id()) &&
		    system_state == SYSTEM_RUNNING)
			cpu_die();
	}

	return 0;
}

#endif /* CONFIG_PPC_PSERIES */

static int native_idle(void)
{
	while(1) {
		/* check CPU type here */
		if (!need_resched())
			power4_idle();
		if (need_resched())
			schedule();

		if (cpu_is_offline(_smp_processor_id()) &&
		    system_state == SYSTEM_RUNNING)
			cpu_die();
	}
	return 0;
}

#endif /* CONFIG_PPC_ISERIES */

void cpu_idle(void)
{
	idle_loop();
}

int powersave_nap;

#ifdef CONFIG_SYSCTL
/*
 * Register the sysctl to set/clear powersave_nap.
 */
static ctl_table powersave_nap_ctl_table[]={
	{
		.ctl_name	= KERN_PPC_POWERSAVE_NAP,
		.procname	= "powersave-nap",
		.data		= &powersave_nap,
		.maxlen		= sizeof(int),
		.mode		= 0644,
		.proc_handler	= &proc_dointvec,
	},
	{ 0, },
};
static ctl_table powersave_nap_sysctl_root[] = {
	{ 1, "kernel", NULL, 0, 0755, powersave_nap_ctl_table, },
 	{ 0,},
};

static int __init
register_powersave_nap_sysctl(void)
{
	register_sysctl_table(powersave_nap_sysctl_root, 0);

	return 0;
}
__initcall(register_powersave_nap_sysctl);
#endif

int idle_setup(void)
{
	/*
	 * Move that junk to each platform specific file, eventually define
	 * a pSeries_idle for shared processor stuff
	 */
#ifdef CONFIG_PPC_ISERIES
	idle_loop = iSeries_idle;
	return 1;
#else
	idle_loop = default_idle;
#endif
#ifdef CONFIG_PPC_PSERIES
	if (systemcfg->platform & PLATFORM_PSERIES) {
		if (cur_cpu_spec->firmware_features & FW_FEATURE_SPLPAR) {
			if (get_paca()->lppaca.shared_proc) {
				printk(KERN_INFO "Using shared processor idle loop\n");
				idle_loop = shared_idle;
			} else {
				printk(KERN_INFO "Using dedicated idle loop\n");
				idle_loop = dedicated_idle;
			}
		} else {
			printk(KERN_INFO "Using default idle loop\n");
			idle_loop = default_idle;
		}
	}
#endif /* CONFIG_PPC_PSERIES */
#ifndef CONFIG_PPC_ISERIES
	if (systemcfg->platform == PLATFORM_POWERMAC ||
	    systemcfg->platform == PLATFORM_MAPLE) {
		printk(KERN_INFO "Using native/NAP idle loop\n");
		idle_loop = native_idle;
	}
#endif /* CONFIG_PPC_ISERIES */

	return 1;
}
OpenPOWER on IntegriCloud