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                 .flags = CPUIDLE_FLAG_TIME_VALID,
 146                 .exit_latency = 0,
 147                 .target_residency = 0,
 148                 .enter = &snooze_loop },
 149         { /* CEDE */
 150                 .name = "CEDE",
 151                 .desc = "CEDE",
 152                 .flags = CPUIDLE_FLAG_TIME_VALID,
 153                 .exit_latency = 10,
 154                 .target_residency = 100,
 155                 .enter = &dedicated_cede_loop },
 156 };
 157
 158 /*
 159  * States for shared partition case.
 160  */
 161 static struct cpuidle_state shared_states[] = {
 162         { /* Shared Cede */
 163                 .name = "Shared Cede",
 164                 .desc = "Shared Cede",
 165                 .flags = CPUIDLE_FLAG_TIME_VALID,
 166                 .exit_latency = 0,
 167                 .target_residency = 0,
 168                 .enter = &shared_cede_loop },
 169 };
 170
 171 static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n,
 172                         unsigned long action, void *hcpu)
 173 {
 174         int hotcpu = (unsigned long)hcpu;
 175         struct cpuidle_device *dev =
 176                                 per_cpu(cpuidle_devices, hotcpu);
 177
 178         if (dev && cpuidle_get_driver()) {
 179                 switch (action) {
 180                 case CPU_ONLINE:
 181                 case CPU_ONLINE_FROZEN:
 182                         cpuidle_pause_and_lock();
 183                         cpuidle_enable_device(dev);
 184                         cpuidle_resume_and_unlock();
 185                         break;
 186
 187                 case CPU_DEAD:
 188                 case CPU_DEAD_FROZEN:
 189                         cpuidle_pause_and_lock();
 190                         cpuidle_disable_device(dev);
 191                         cpuidle_resume_and_unlock();
 192                         break;
 193
 194                 default:
 195                         return NOTIFY_DONE;
 196                 }
 197         }
 198         return NOTIFY_OK;
 199 }
 200
 201 static struct notifier_block setup_hotplug_notifier = {
 202         .notifier_call = pseries_cpuidle_add_cpu_notifier,
 203 };
 204
 205 /*
 206  * pseries_cpuidle_driver_init()
 207  */
 208 static int pseries_cpuidle_driver_init(void)
 209 {
 210         int idle_state;
 211         struct cpuidle_driver *drv = &pseries_idle_driver;
 212
 213         drv->state_count = 0;
 214
 215         for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
 216                 /* Is the state not enabled? */
 217                 if (cpuidle_state_table[idle_state].enter == NULL)
 218                         continue;
 219
 220                 drv->states[drv->state_count] = /* structure copy */
 221                         cpuidle_state_table[idle_state];
 222
 223                 drv->state_count += 1;
 224         }
 225
 226         return 0;
 227 }
 228
 229 /*
 230  * pseries_idle_probe()
 231  * Choose state table for shared versus dedicated partition
 232  */
 233 static int pseries_idle_probe(void)
 234 {
 235
 236         if (cpuidle_disable != IDLE_NO_OVERRIDE)
 237                 return -ENODEV;
 238
 239         if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
 240                 if (lppaca_shared_proc(get_lppaca())) {
 241                         cpuidle_state_table = shared_states;
 242                         max_idle_state = ARRAY_SIZE(shared_states);
 243                 } else {
 244                         cpuidle_state_table = dedicated_states;
 245                         max_idle_state = ARRAY_SIZE(dedicated_states);
 246                 }
 247         } else
 248                 return -ENODEV;
 249
 250         return 0;
 251 }
 252
 253 static int __init pseries_processor_idle_init(void)
 254 {
 255         int retval;
 256
 257         retval = pseries_idle_probe();
 258         if (retval)
 259                 return retval;
 260
 261         pseries_cpuidle_driver_init();
 262         retval = cpuidle_register(&pseries_idle_driver, NULL);
 263         if (retval) {
 264                 printk(KERN_DEBUG "Registration of pseries driver failed.\n");
 265                 return retval;
 266         }
 267
 268         register_cpu_notifier(&setup_hotplug_notifier);
 269         printk(KERN_DEBUG "pseries_idle_driver registered\n");
 270         return 0;
 271 }
 272
 273 device_initcall(pseries_processor_idle_init);