kernel/drivers/cpuidle/cpuidle-pseries.c

   1 /*
   2  *  cpuidle-pseries - 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 #include <asm/plpar_wrappers.h>
  22
  23 struct cpuidle_driver pseries_idle_driver = {
  24         .name             = "pseries_idle",
  25         .owner            = THIS_MODULE,
  26 };
  27
  28 static int max_idle_state;
  29 static struct cpuidle_state *cpuidle_state_table;
  30
  31 static inline void idle_loop_prolog(unsigned long *in_purr)
  32 {
  33         ppc64_runlatch_off();
  34         *in_purr = mfspr(SPRN_PURR);
  35         /*
  36          * Indicate to the HV that we are idle. Now would be
  37          * a good time to find other work to dispatch.
  38          */
  39         get_lppaca()->idle = 1;
  40 }
  41
  42 static inline void idle_loop_epilog(unsigned long in_purr)
  43 {
  44         u64 wait_cycles;
  45
  46         wait_cycles = be64_to_cpu(get_lppaca()->wait_state_cycles);
  47         wait_cycles += mfspr(SPRN_PURR) - in_purr;
  48         get_lppaca()->wait_state_cycles = cpu_to_be64(wait_cycles);
  49         get_lppaca()->idle = 0;
  50
  51         if (irqs_disabled())
  52                 local_irq_enable();
  53         ppc64_runlatch_on();
  54 }
  55
  56 static int snooze_loop(struct cpuidle_device *dev,
  57                         struct cpuidle_driver *drv,
  58                         int index)
  59 {
  60         unsigned long in_purr;
  61
  62         idle_loop_prolog(&in_purr);
  63         local_irq_enable();
  64         set_thread_flag(TIF_POLLING_NRFLAG);
  65
  66         while (!need_resched()) {
  67                 HMT_low();
  68                 HMT_very_low();
  69         }
  70
  71         HMT_medium();
  72         clear_thread_flag(TIF_POLLING_NRFLAG);
  73         smp_mb();
  74
  75         idle_loop_epilog(in_purr);
  76
  77         return index;
  78 }
  79
  80 static void check_and_cede_processor(void)
  81 {
  82         /*
  83          * Ensure our interrupt state is properly tracked,
  84          * also checks if no interrupt has occurred while we
  85          * were soft-disabled
  86          */
  87         if (prep_irq_for_idle()) {
  88                 cede_processor();
  89 #ifdef CONFIG_TRACE_IRQFLAGS
  90                 /* Ensure that H_CEDE returns with IRQs on */
  91                 if (WARN_ON(!(mfmsr() & MSR_EE)))
  92                         __hard_irq_enable();
  93 #endif
  94         }
  95 }
  96
  97 static int dedicated_cede_loop(struct cpuidle_device *dev,
  98                                 struct cpuidle_driver *drv,
  99                                 int index)
 100 {
 101         unsigned long in_purr;
 102
 103         idle_loop_prolog(&in_purr);
 104         get_lppaca()->donate_dedicated_cpu = 1;
 105
 106         HMT_medium();
 107         check_and_cede_processor();
 108
 109         get_lppaca()->donate_dedicated_cpu = 0;
 110
 111         idle_loop_epilog(in_purr);
 112
 113         return index;
 114 }
 115
 116 static int shared_cede_loop(struct cpuidle_device *dev,
 117                         struct cpuidle_driver *drv,
 118                         int index)
 119 {
 120         unsigned long in_purr;
 121
 122         idle_loop_prolog(&in_purr);
 123
 124         /*
 125          * Yield the processor to the hypervisor.  We return if
 126          * an external interrupt occurs (which are driven prior
 127          * to returning here) or if a prod occurs from another
 128          * processor. When returning here, external interrupts
 129          * are enabled.
 130          */
 131         check_and_cede_processor();
 132
 133         idle_loop_epilog(in_purr);
 134
 135         return index;
 136 }
 137
 138 /*
 139  * States for dedicated partition case.
 140  */
 141 static struct cpuidle_state dedicated_states[] = {
 142         { /* Snooze */
 143                 .name = "snooze",
 144                 .desc = "snooze",
 145                 .exit_latency = 0,
 146                 .target_residency = 0,
 147                 .enter = &snooze_loop },
 148         { /* CEDE */
 149                 .name = "CEDE",
 150                 .desc = "CEDE",
 151                 .exit_latency = 10,
 152                 .target_residency = 100,
 153                 .enter = &dedicated_cede_loop },
 154 };
 155
 156 /*
 157  * States for shared partition case.
 158  */
 159 static struct cpuidle_state shared_states[] = {
 160         { /* Shared Cede */
 161                 .name = "Shared Cede",
 162                 .desc = "Shared Cede",
 163                 .exit_latency = 0,
 164                 .target_residency = 0,
 165                 .enter = &shared_cede_loop },
 166 };
 167
 168 static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n,
 169                         unsigned long action, void *hcpu)
 170 {
 171         int hotcpu = (unsigned long)hcpu;
 172         struct cpuidle_device *dev =
 173                                 per_cpu(cpuidle_devices, hotcpu);
 174
 175         if (dev && cpuidle_get_driver()) {
 176                 switch (action) {
 177                 case CPU_ONLINE:
 178                 case CPU_ONLINE_FROZEN:
 179                         cpuidle_pause_and_lock();
 180                         cpuidle_enable_device(dev);
 181                         cpuidle_resume_and_unlock();
 182                         break;
 183
 184                 case CPU_DEAD:
 185                 case CPU_DEAD_FROZEN:
 186                         cpuidle_pause_and_lock();
 187                         cpuidle_disable_device(dev);
 188                         cpuidle_resume_and_unlock();
 189                         break;
 190
 191                 default:
 192                         return NOTIFY_DONE;
 193                 }
 194         }
 195         return NOTIFY_OK;
 196 }
 197
 198 static struct notifier_block setup_hotplug_notifier = {
 199         .notifier_call = pseries_cpuidle_add_cpu_notifier,
 200 };
 201
 202 /*
 203  * pseries_cpuidle_driver_init()
 204  */
 205 static int pseries_cpuidle_driver_init(void)
 206 {
 207         int idle_state;
 208         struct cpuidle_driver *drv = &pseries_idle_driver;
 209
 210         drv->state_count = 0;
 211
 212         for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
 213                 /* Is the state not enabled? */
 214                 if (cpuidle_state_table[idle_state].enter == NULL)
 215                         continue;
 216
 217                 drv->states[drv->state_count] = /* structure copy */
 218                         cpuidle_state_table[idle_state];
 219
 220                 drv->state_count += 1;
 221         }
 222
 223         return 0;
 224 }
 225
 226 /*
 227  * pseries_idle_probe()
 228  * Choose state table for shared versus dedicated partition
 229  */
 230 static int pseries_idle_probe(void)
 231 {
 232
 233         if (cpuidle_disable != IDLE_NO_OVERRIDE)
 234                 return -ENODEV;
 235
 236         if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
 237                 if (lppaca_shared_proc(get_lppaca())) {
 238                         cpuidle_state_table = shared_states;
 239                         max_idle_state = ARRAY_SIZE(shared_states);
 240                 } else {
 241                         cpuidle_state_table = dedicated_states;
 242                         max_idle_state = ARRAY_SIZE(dedicated_states);
 243                 }
 244         } else
 245                 return -ENODEV;
 246
 247         return 0;
 248 }
 249
 250 static int __init pseries_processor_idle_init(void)
 251 {
 252         int retval;
 253
 254         retval = pseries_idle_probe();
 255         if (retval)
 256                 return retval;
 257
 258         pseries_cpuidle_driver_init();
 259         retval = cpuidle_register(&pseries_idle_driver, NULL);
 260         if (retval) {
 261                 printk(KERN_DEBUG "Registration of pseries driver failed.\n");
 262                 return retval;
 263         }
 264
 265         register_cpu_notifier(&setup_hotplug_notifier);
 266         printk(KERN_DEBUG "pseries_idle_driver registered\n");
 267         return 0;
 268 }
 269
 270 device_initcall(pseries_processor_idle_init);