arch/powerpc/platforms/pseries/processor_idle.c

   1 /*
   2  *  processor_idle - idle state cpuidle driver.
   3  *  Adapted from drivers/idle/intel_idle.c and
   4  *  drivers/acpi/processor_idle.c
   5  *
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/moduleparam.h>
  12 #include <linux/cpuidle.h>
  13 #include <linux/cpu.h>
  14 #include <linux/notifier.h>
  15
  16 #include <asm/paca.h>
  17 #include <asm/reg.h>
  18 #include <asm/machdep.h>
  19 #include <asm/firmware.h>
  20 #include <asm/runlatch.h>
  21
  22 #include "plpar_wrappers.h"
  23 #include "pseries.h"
  24
  25 struct cpuidle_driver pseries_idle_driver = {
  26         .name =         "pseries_idle",
  27         .owner =        THIS_MODULE,
  28 };
  29
  30 #define MAX_IDLE_STATE_COUNT    2
  31
  32 static int max_idle_state = MAX_IDLE_STATE_COUNT - 1;
  33 static struct cpuidle_device __percpu *pseries_cpuidle_devices;
  34 static struct cpuidle_state *cpuidle_state_table;
  35
  36 void update_smt_snooze_delay(int snooze)
  37 {
  38         struct cpuidle_driver *drv = cpuidle_get_driver();
  39         if (drv)
  40                 drv->states[0].target_residency = snooze;
  41 }
  42
  43 static inline void idle_loop_prolog(unsigned long *in_purr, ktime_t *kt_before)
  44 {
  45
  46         *kt_before = ktime_get_real();
  47         *in_purr = mfspr(SPRN_PURR);
  48         /*
  49          * Indicate to the HV that we are idle. Now would be
  50          * a good time to find other work to dispatch.
  51          */
  52         get_lppaca()->idle = 1;
  53 }
  54
  55 static inline  s64 idle_loop_epilog(unsigned long in_purr, ktime_t kt_before)
  56 {
  57         get_lppaca()->wait_state_cycles += mfspr(SPRN_PURR) - in_purr;
  58         get_lppaca()->idle = 0;
  59
  60         return ktime_to_us(ktime_sub(ktime_get_real(), kt_before));
  61 }
  62
  63 static int snooze_loop(struct cpuidle_device *dev,
  64                         struct cpuidle_driver *drv,
  65                         int index)
  66 {
  67         unsigned long in_purr;
  68         ktime_t kt_before;
  69         unsigned long start_snooze;
  70         long snooze = drv->states[0].target_residency;
  71
  72         idle_loop_prolog(&in_purr, &kt_before);
  73
  74         if (snooze) {
  75                 start_snooze = get_tb() + snooze * tb_ticks_per_usec;
  76                 local_irq_enable();
  77                 set_thread_flag(TIF_POLLING_NRFLAG);
  78
  79                 while ((snooze < 0) || (get_tb() < start_snooze)) {
  80                         if (need_resched() || cpu_is_offline(dev->cpu))
  81                                 goto out;
  82                         ppc64_runlatch_off();
  83                         HMT_low();
  84                         HMT_very_low();
  85                 }
  86
  87                 HMT_medium();
  88                 clear_thread_flag(TIF_POLLING_NRFLAG);
  89                 smp_mb();
  90                 local_irq_disable();
  91         }
  92
  93 out:
  94         HMT_medium();
  95         dev->last_residency =
  96                 (int)idle_loop_epilog(in_purr, kt_before);
  97         return index;
  98 }
  99
 100 static void check_and_cede_processor(void)
 101 {
 102         /*
 103          * Ensure our interrupt state is properly tracked,
 104          * also checks if no interrupt has occurred while we
 105          * were soft-disabled
 106          */
 107         if (prep_irq_for_idle()) {
 108                 cede_processor();
 109 #ifdef CONFIG_TRACE_IRQFLAGS
 110                 /* Ensure that H_CEDE returns with IRQs on */
 111                 if (WARN_ON(!(mfmsr() & MSR_EE)))
 112                         __hard_irq_enable();
 113 #endif
 114         }
 115 }
 116
 117 static int dedicated_cede_loop(struct cpuidle_device *dev,
 118                                 struct cpuidle_driver *drv,
 119                                 int index)
 120 {
 121         unsigned long in_purr;
 122         ktime_t kt_before;
 123
 124         idle_loop_prolog(&in_purr, &kt_before);
 125         get_lppaca()->donate_dedicated_cpu = 1;
 126
 127         ppc64_runlatch_off();
 128         HMT_medium();
 129         check_and_cede_processor();
 130
 131         get_lppaca()->donate_dedicated_cpu = 0;
 132         dev->last_residency =
 133                 (int)idle_loop_epilog(in_purr, kt_before);
 134         return index;
 135 }
 136
 137 static int shared_cede_loop(struct cpuidle_device *dev,
 138                         struct cpuidle_driver *drv,
 139                         int index)
 140 {
 141         unsigned long in_purr;
 142         ktime_t kt_before;
 143
 144         idle_loop_prolog(&in_purr, &kt_before);
 145
 146         /*
 147          * Yield the processor to the hypervisor.  We return if
 148          * an external interrupt occurs (which are driven prior
 149          * to returning here) or if a prod occurs from another
 150          * processor. When returning here, external interrupts
 151          * are enabled.
 152          */
 153         check_and_cede_processor();
 154
 155         dev->last_residency =
 156                 (int)idle_loop_epilog(in_purr, kt_before);
 157         return index;
 158 }
 159
 160 /*
 161  * States for dedicated partition case.
 162  */
 163 static struct cpuidle_state dedicated_states[MAX_IDLE_STATE_COUNT] = {
 164         { /* Snooze */
 165                 .name = "snooze",
 166                 .desc = "snooze",
 167                 .flags = CPUIDLE_FLAG_TIME_VALID,
 168                 .exit_latency = 0,
 169                 .target_residency = 0,
 170                 .enter = &snooze_loop },
 171         { /* CEDE */
 172                 .name = "CEDE",
 173                 .desc = "CEDE",
 174                 .flags = CPUIDLE_FLAG_TIME_VALID,
 175                 .exit_latency = 1,
 176                 .target_residency = 10,
 177                 .enter = &dedicated_cede_loop },
 178 };
 179
 180 /*
 181  * States for shared partition case.
 182  */
 183 static struct cpuidle_state shared_states[MAX_IDLE_STATE_COUNT] = {
 184         { /* Shared Cede */
 185                 .name = "Shared Cede",
 186                 .desc = "Shared Cede",
 187                 .flags = CPUIDLE_FLAG_TIME_VALID,
 188                 .exit_latency = 0,
 189                 .target_residency = 0,
 190                 .enter = &shared_cede_loop },
 191 };
 192
 193 static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n,
 194                         unsigned long action, void *hcpu)
 195 {
 196         int hotcpu = (unsigned long)hcpu;
 197         struct cpuidle_device *dev =
 198                         per_cpu_ptr(pseries_cpuidle_devices, hotcpu);
 199
 200         if (dev && cpuidle_get_driver()) {
 201                 switch (action) {
 202                 case CPU_ONLINE:
 203                 case CPU_ONLINE_FROZEN:
 204                         cpuidle_pause_and_lock();
 205                         cpuidle_enable_device(dev);
 206                         cpuidle_resume_and_unlock();
 207                         break;
 208
 209                 case CPU_DEAD:
 210                 case CPU_DEAD_FROZEN:
 211                         cpuidle_pause_and_lock();
 212                         cpuidle_disable_device(dev);
 213                         cpuidle_resume_and_unlock();
 214                         break;
 215
 216                 default:
 217                         return NOTIFY_DONE;
 218                 }
 219         }
 220         return NOTIFY_OK;
 221 }
 222
 223 static struct notifier_block setup_hotplug_notifier = {
 224         .notifier_call = pseries_cpuidle_add_cpu_notifier,
 225 };
 226
 227 /*
 228  * pseries_cpuidle_driver_init()
 229  */
 230 static int pseries_cpuidle_driver_init(void)
 231 {
 232         int idle_state;
 233         struct cpuidle_driver *drv = &pseries_idle_driver;
 234
 235         drv->state_count = 0;
 236
 237         for (idle_state = 0; idle_state < MAX_IDLE_STATE_COUNT; ++idle_state) {
 238
 239                 if (idle_state > max_idle_state)
 240                         break;
 241
 242                 /* is the state not enabled? */
 243                 if (cpuidle_state_table[idle_state].enter == NULL)
 244                         continue;
 245
 246                 drv->states[drv->state_count] = /* structure copy */
 247                         cpuidle_state_table[idle_state];
 248
 249                 if (cpuidle_state_table == dedicated_states)
 250                         drv->states[drv->state_count].target_residency =
 251                                 __get_cpu_var(smt_snooze_delay);
 252
 253                 drv->state_count += 1;
 254         }
 255
 256         return 0;
 257 }
 258
 259 /* pseries_idle_devices_uninit(void)
 260  * unregister cpuidle devices and de-allocate memory
 261  */
 262 static void pseries_idle_devices_uninit(void)
 263 {
 264         int i;
 265         struct cpuidle_device *dev;
 266
 267         for_each_possible_cpu(i) {
 268                 dev = per_cpu_ptr(pseries_cpuidle_devices, i);
 269                 cpuidle_unregister_device(dev);
 270         }
 271
 272         free_percpu(pseries_cpuidle_devices);
 273         return;
 274 }
 275
 276 /* pseries_idle_devices_init()
 277  * allocate, initialize and register cpuidle device
 278  */
 279 static int pseries_idle_devices_init(void)
 280 {
 281         int i;
 282         struct cpuidle_driver *drv = &pseries_idle_driver;
 283         struct cpuidle_device *dev;
 284
 285         pseries_cpuidle_devices = alloc_percpu(struct cpuidle_device);
 286         if (pseries_cpuidle_devices == NULL)
 287                 return -ENOMEM;
 288
 289         for_each_possible_cpu(i) {
 290                 dev = per_cpu_ptr(pseries_cpuidle_devices, i);
 291                 dev->state_count = drv->state_count;
 292                 dev->cpu = i;
 293                 if (cpuidle_register_device(dev)) {
 294                         printk(KERN_DEBUG \
 295                                 "cpuidle_register_device %d failed!\n", i);
 296                         return -EIO;
 297                 }
 298         }
 299
 300         return 0;
 301 }
 302
 303 /*
 304  * pseries_idle_probe()
 305  * Choose state table for shared versus dedicated partition
 306  */
 307 static int pseries_idle_probe(void)
 308 {
 309
 310         if (!firmware_has_feature(FW_FEATURE_SPLPAR))
 311                 return -ENODEV;
 312
 313         if (cpuidle_disable != IDLE_NO_OVERRIDE)
 314                 return -ENODEV;
 315
 316         if (max_idle_state == 0) {
 317                 printk(KERN_DEBUG "pseries processor idle disabled.\n");
 318                 return -EPERM;
 319         }
 320
 321         if (get_lppaca()->shared_proc)
 322                 cpuidle_state_table = shared_states;
 323         else
 324                 cpuidle_state_table = dedicated_states;
 325
 326         return 0;
 327 }
 328
 329 static int __init pseries_processor_idle_init(void)
 330 {
 331         int retval;
 332
 333         retval = pseries_idle_probe();
 334         if (retval)
 335                 return retval;
 336
 337         pseries_cpuidle_driver_init();
 338         retval = cpuidle_register_driver(&pseries_idle_driver);
 339         if (retval) {
 340                 printk(KERN_DEBUG "Registration of pseries driver failed.\n");
 341                 return retval;
 342         }
 343
 344         retval = pseries_idle_devices_init();
 345         if (retval) {
 346                 pseries_idle_devices_uninit();
 347                 cpuidle_unregister_driver(&pseries_idle_driver);
 348                 return retval;
 349         }
 350
 351         register_cpu_notifier(&setup_hotplug_notifier);
 352         printk(KERN_DEBUG "pseries_idle_driver registered\n");
 353
 354         return 0;
 355 }
 356
 357 static void __exit pseries_processor_idle_exit(void)
 358 {
 359
 360         unregister_cpu_notifier(&setup_hotplug_notifier);
 361         pseries_idle_devices_uninit();
 362         cpuidle_unregister_driver(&pseries_idle_driver);
 363
 364         return;
 365 }
 366
 367 module_init(pseries_processor_idle_init);
 368 module_exit(pseries_processor_idle_exit);
 369
 370 MODULE_AUTHOR("Deepthi Dharwar <deepthi@linux.vnet.ibm.com>");
 371 MODULE_DESCRIPTION("Cpuidle driver for POWER");
 372 MODULE_LICENSE("GPL");