arch/ppc64/kernel/idle.c

   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
  45 static void yield_shared_processor(void)
  46 {
  47         unsigned long tb;
  48         unsigned long yieldTime;
  49
  50         HvCall_setEnabledInterrupts(HvCall_MaskIPI |
  51                                     HvCall_MaskLpEvent |
  52                                     HvCall_MaskLpProd |
  53                                     HvCall_MaskTimeout);
  54
  55         tb = get_tb();
  56         /* Compute future tb value when yield should expire */
  57         HvCall_yieldProcessor(HvCall_YieldTimed, tb+tb_ticks_per_jiffy);
  58
  59         yieldTime = get_tb() - tb;
  60         if (yieldTime > maxYieldTime)
  61                 maxYieldTime = yieldTime;
  62
  63         if (yieldTime < minYieldTime)
  64                 minYieldTime = yieldTime;
  65
  66         /*
  67          * The decrementer stops during the yield.  Force a fake decrementer
  68          * here and let the timer_interrupt code sort out the actual time.
  69          */
  70         get_paca()->lppaca.int_dword.fields.decr_int = 1;
  71         process_iSeries_events();
  72 }
  73
  74 static int iSeries_idle(void)
  75 {
  76         struct paca_struct *lpaca;
  77         long oldval;
  78         unsigned long CTRL;
  79
  80         /* ensure iSeries run light will be out when idle */
  81         clear_thread_flag(TIF_RUN_LIGHT);
  82         CTRL = mfspr(CTRLF);
  83         CTRL &= ~RUNLATCH;
  84         mtspr(CTRLT, CTRL);
  85
  86         lpaca = get_paca();
  87
  88         while (1) {
  89                 if (lpaca->lppaca.shared_proc) {
  90                         if (ItLpQueue_isLpIntPending(lpaca->lpqueue_ptr))
  91                                 process_iSeries_events();
  92                         if (!need_resched())
  93                                 yield_shared_processor();
  94                 } else {
  95                         oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
  96
  97                         if (!oldval) {
  98                                 set_thread_flag(TIF_POLLING_NRFLAG);
  99
 100                                 while (!need_resched()) {
 101                                         HMT_medium();
 102                                         if (ItLpQueue_isLpIntPending(lpaca->lpqueue_ptr))
 103                                                 process_iSeries_events();
 104                                         HMT_low();
 105                                 }
 106
 107                                 HMT_medium();
 108                                 clear_thread_flag(TIF_POLLING_NRFLAG);
 109                         } else {
 110                                 set_need_resched();
 111                         }
 112                 }
 113
 114                 schedule();
 115         }
 116
 117         return 0;
 118 }
 119
 120 #else
 121
 122 static int default_idle(void)
 123 {
 124         long oldval;
 125         unsigned int cpu = smp_processor_id();
 126
 127         while (1) {
 128                 oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
 129
 130                 if (!oldval) {
 131                         set_thread_flag(TIF_POLLING_NRFLAG);
 132
 133                         while (!need_resched() && !cpu_is_offline(cpu)) {
 134                                 barrier();
 135                                 /*
 136                                  * Go into low thread priority and possibly
 137                                  * low power mode.
 138                                  */
 139                                 HMT_low();
 140                                 HMT_very_low();
 141                         }
 142
 143                         HMT_medium();
 144                         clear_thread_flag(TIF_POLLING_NRFLAG);
 145                 } else {
 146                         set_need_resched();
 147                 }
 148
 149                 schedule();
 150                 if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
 151                         cpu_die();
 152         }
 153
 154         return 0;
 155 }
 156
 157 #ifdef CONFIG_PPC_PSERIES
 158
 159 DECLARE_PER_CPU(unsigned long, smt_snooze_delay);
 160
 161 int dedicated_idle(void)
 162 {
 163         long oldval;
 164         struct paca_struct *lpaca = get_paca(), *ppaca;
 165         unsigned long start_snooze;
 166         unsigned long *smt_snooze_delay = &__get_cpu_var(smt_snooze_delay);
 167         unsigned int cpu = smp_processor_id();
 168
 169         ppaca = &paca[cpu ^ 1];
 170
 171         while (1) {
 172                 /*
 173                  * Indicate to the HV that we are idle. Now would be
 174                  * a good time to find other work to dispatch.
 175                  */
 176                 lpaca->lppaca.idle = 1;
 177
 178                 oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
 179                 if (!oldval) {
 180                         set_thread_flag(TIF_POLLING_NRFLAG);
 181                         start_snooze = __get_tb() +
 182                                 *smt_snooze_delay * tb_ticks_per_usec;
 183                         while (!need_resched() && !cpu_is_offline(cpu)) {
 184                                 /*
 185                                  * Go into low thread priority and possibly
 186                                  * low power mode.
 187                                  */
 188                                 HMT_low();
 189                                 HMT_very_low();
 190
 191                                 if (*smt_snooze_delay == 0 ||
 192                                     __get_tb() < start_snooze)
 193                                         continue;
 194
 195                                 HMT_medium();
 196
 197                                 if (!(ppaca->lppaca.idle)) {
 198                                         local_irq_disable();
 199
 200                                         /*
 201                                          * We are about to sleep the thread
 202                                          * and so wont be polling any
 203                                          * more.
 204                                          */
 205                                         clear_thread_flag(TIF_POLLING_NRFLAG);
 206
 207                                         /*
 208                                          * SMT dynamic mode. Cede will result
 209                                          * in this thread going dormant, if the
 210                                          * partner thread is still doing work.
 211                                          * Thread wakes up if partner goes idle,
 212                                          * an interrupt is presented, or a prod
 213                                          * occurs.  Returning from the cede
 214                                          * enables external interrupts.
 215                                          */
 216                                         if (!need_resched())
 217                                                 cede_processor();
 218                                         else
 219                                                 local_irq_enable();
 220                                 } else {
 221                                         /*
 222                                          * Give the HV an opportunity at the
 223                                          * processor, since we are not doing
 224                                          * any work.
 225                                          */
 226                                         poll_pending();
 227                                 }
 228                         }
 229
 230                         clear_thread_flag(TIF_POLLING_NRFLAG);
 231                 } else {
 232                         set_need_resched();
 233                 }
 234
 235                 HMT_medium();
 236                 lpaca->lppaca.idle = 0;
 237                 schedule();
 238                 if (cpu_is_offline(cpu) && system_state == SYSTEM_RUNNING)
 239                         cpu_die();
 240         }
 241         return 0;
 242 }
 243
 244 static int shared_idle(void)
 245 {
 246         struct paca_struct *lpaca = get_paca();
 247         unsigned int cpu = smp_processor_id();
 248
 249         while (1) {
 250                 /*
 251                  * Indicate to the HV that we are idle. Now would be
 252                  * a good time to find other work to dispatch.
 253                  */
 254                 lpaca->lppaca.idle = 1;
 255
 256                 while (!need_resched() && !cpu_is_offline(cpu)) {
 257                         local_irq_disable();
 258
 259                         /*
 260                          * Yield the processor to the hypervisor.  We return if
 261                          * an external interrupt occurs (which are driven prior
 262                          * to returning here) or if a prod occurs from another
 263                          * processor. When returning here, external interrupts
 264                          * are enabled.
 265                          *
 266                          * Check need_resched() again with interrupts disabled
 267                          * to avoid a race.
 268                          */
 269                         if (!need_resched())
 270                                 cede_processor();
 271                         else
 272                                 local_irq_enable();
 273                 }
 274
 275                 HMT_medium();
 276                 lpaca->lppaca.idle = 0;
 277                 schedule();
 278                 if (cpu_is_offline(smp_processor_id()) &&
 279                     system_state == SYSTEM_RUNNING)
 280                         cpu_die();
 281         }
 282
 283         return 0;
 284 }
 285
 286 #endif /* CONFIG_PPC_PSERIES */
 287
 288 static int native_idle(void)
 289 {
 290         while(1) {
 291                 /* check CPU type here */
 292                 if (!need_resched())
 293                         power4_idle();
 294                 if (need_resched())
 295                         schedule();
 296
 297                 if (cpu_is_offline(_smp_processor_id()) &&
 298                     system_state == SYSTEM_RUNNING)
 299                         cpu_die();
 300         }
 301         return 0;
 302 }
 303
 304 #endif /* CONFIG_PPC_ISERIES */
 305
 306 void cpu_idle(void)
 307 {
 308         idle_loop();
 309 }
 310
 311 int powersave_nap;
 312
 313 #ifdef CONFIG_SYSCTL
 314 /*
 315  * Register the sysctl to set/clear powersave_nap.
 316  */
 317 static ctl_table powersave_nap_ctl_table[]={
 318         {
 319                 .ctl_name       = KERN_PPC_POWERSAVE_NAP,
 320                 .procname       = "powersave-nap",
 321                 .data           = &powersave_nap,
 322                 .maxlen         = sizeof(int),
 323                 .mode           = 0644,
 324                 .proc_handler   = &proc_dointvec,
 325         },
 326         { 0, },
 327 };
 328 static ctl_table powersave_nap_sysctl_root[] = {
 329         { 1, "kernel", NULL, 0, 0755, powersave_nap_ctl_table, },
 330         { 0,},
 331 };
 332
 333 static int __init
 334 register_powersave_nap_sysctl(void)
 335 {
 336         register_sysctl_table(powersave_nap_sysctl_root, 0);
 337
 338         return 0;
 339 }
 340 __initcall(register_powersave_nap_sysctl);
 341 #endif
 342
 343 int idle_setup(void)
 344 {
 345         /*
 346          * Move that junk to each platform specific file, eventually define
 347          * a pSeries_idle for shared processor stuff
 348          */
 349 #ifdef CONFIG_PPC_ISERIES
 350         idle_loop = iSeries_idle;
 351         return 1;
 352 #else
 353         idle_loop = default_idle;
 354 #endif
 355 #ifdef CONFIG_PPC_PSERIES
 356         if (systemcfg->platform & PLATFORM_PSERIES) {
 357                 if (cur_cpu_spec->firmware_features & FW_FEATURE_SPLPAR) {
 358                         if (get_paca()->lppaca.shared_proc) {
 359                                 printk(KERN_INFO "Using shared processor idle loop\n");
 360                                 idle_loop = shared_idle;
 361                         } else {
 362                                 printk(KERN_INFO "Using dedicated idle loop\n");
 363                                 idle_loop = dedicated_idle;
 364                         }
 365                 } else {
 366                         printk(KERN_INFO "Using default idle loop\n");
 367                         idle_loop = default_idle;
 368                 }
 369         }
 370 #endif /* CONFIG_PPC_PSERIES */
 371 #ifndef CONFIG_PPC_ISERIES
 372         if (systemcfg->platform == PLATFORM_POWERMAC ||
 373             systemcfg->platform == PLATFORM_MAPLE) {
 374                 printk(KERN_INFO "Using native/NAP idle loop\n");
 375                 idle_loop = native_idle;
 376         }
 377 #endif /* CONFIG_PPC_ISERIES */
 378
 379         return 1;
 380 }