drivers/cpuidle/cpuidle-powernv.c

   1 /*
   2  *  cpuidle-powernv - idle state cpuidle driver.
   3  *  Adapted from drivers/cpuidle/cpuidle-pseries
   4  *
   5  */
   6
   7 #include <linux/kernel.h>
   8 #include <linux/module.h>
   9 #include <linux/init.h>
  10 #include <linux/moduleparam.h>
  11 #include <linux/cpuidle.h>
  12 #include <linux/cpu.h>
  13 #include <linux/notifier.h>
  14 #include <linux/clockchips.h>
  15 #include <linux/of.h>
  16
  17 #include <asm/machdep.h>
  18 #include <asm/firmware.h>
  19 #include <asm/runlatch.h>
  20
  21 /* Flags and constants used in PowerNV platform */
  22
  23 #define MAX_POWERNV_IDLE_STATES 8
  24 #define IDLE_USE_INST_NAP       0x00010000 /* Use nap instruction */
  25 #define IDLE_USE_INST_SLEEP     0x00020000 /* Use sleep instruction */
  26
  27 struct cpuidle_driver powernv_idle_driver = {
  28         .name             = "powernv_idle",
  29         .owner            = THIS_MODULE,
  30 };
  31
  32 static int max_idle_state;
  33 static struct cpuidle_state *cpuidle_state_table;
  34
  35 static int snooze_loop(struct cpuidle_device *dev,
  36                         struct cpuidle_driver *drv,
  37                         int index)
  38 {
  39         local_irq_enable();
  40         set_thread_flag(TIF_POLLING_NRFLAG);
  41
  42         ppc64_runlatch_off();
  43         while (!need_resched()) {
  44                 HMT_low();
  45                 HMT_very_low();
  46         }
  47
  48         HMT_medium();
  49         ppc64_runlatch_on();
  50         clear_thread_flag(TIF_POLLING_NRFLAG);
  51         smp_mb();
  52         return index;
  53 }
  54
  55 static int nap_loop(struct cpuidle_device *dev,
  56                         struct cpuidle_driver *drv,
  57                         int index)
  58 {
  59         ppc64_runlatch_off();
  60         power7_idle();
  61         ppc64_runlatch_on();
  62         return index;
  63 }
  64
  65 static int fastsleep_loop(struct cpuidle_device *dev,
  66                                 struct cpuidle_driver *drv,
  67                                 int index)
  68 {
  69         unsigned long old_lpcr = mfspr(SPRN_LPCR);
  70         unsigned long new_lpcr;
  71
  72         if (unlikely(system_state < SYSTEM_RUNNING))
  73                 return index;
  74
  75         new_lpcr = old_lpcr;
  76         new_lpcr &= ~(LPCR_MER | LPCR_PECE); /* lpcr[mer] must be 0 */
  77
  78         /* exit powersave upon external interrupt, but not decrementer
  79          * interrupt.
  80          */
  81         new_lpcr |= LPCR_PECE0;
  82
  83         mtspr(SPRN_LPCR, new_lpcr);
  84         power7_sleep();
  85
  86         mtspr(SPRN_LPCR, old_lpcr);
  87
  88         return index;
  89 }
  90
  91 /*
  92  * States for dedicated partition case.
  93  */
  94 static struct cpuidle_state powernv_states[MAX_POWERNV_IDLE_STATES] = {
  95         { /* Snooze */
  96                 .name = "snooze",
  97                 .desc = "snooze",
  98                 .flags = CPUIDLE_FLAG_TIME_VALID,
  99                 .exit_latency = 0,
 100                 .target_residency = 0,
 101                 .enter = &snooze_loop },
 102 };
 103
 104 static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
 105                         unsigned long action, void *hcpu)
 106 {
 107         int hotcpu = (unsigned long)hcpu;
 108         struct cpuidle_device *dev =
 109                                 per_cpu(cpuidle_devices, hotcpu);
 110
 111         if (dev && cpuidle_get_driver()) {
 112                 switch (action) {
 113                 case CPU_ONLINE:
 114                 case CPU_ONLINE_FROZEN:
 115                         cpuidle_pause_and_lock();
 116                         cpuidle_enable_device(dev);
 117                         cpuidle_resume_and_unlock();
 118                         break;
 119
 120                 case CPU_DEAD:
 121                 case CPU_DEAD_FROZEN:
 122                         cpuidle_pause_and_lock();
 123                         cpuidle_disable_device(dev);
 124                         cpuidle_resume_and_unlock();
 125                         break;
 126
 127                 default:
 128                         return NOTIFY_DONE;
 129                 }
 130         }
 131         return NOTIFY_OK;
 132 }
 133
 134 static struct notifier_block setup_hotplug_notifier = {
 135         .notifier_call = powernv_cpuidle_add_cpu_notifier,
 136 };
 137
 138 /*
 139  * powernv_cpuidle_driver_init()
 140  */
 141 static int powernv_cpuidle_driver_init(void)
 142 {
 143         int idle_state;
 144         struct cpuidle_driver *drv = &powernv_idle_driver;
 145
 146         drv->state_count = 0;
 147
 148         for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
 149                 /* Is the state not enabled? */
 150                 if (cpuidle_state_table[idle_state].enter == NULL)
 151                         continue;
 152
 153                 drv->states[drv->state_count] = /* structure copy */
 154                         cpuidle_state_table[idle_state];
 155
 156                 drv->state_count += 1;
 157         }
 158
 159         return 0;
 160 }
 161
 162 static int powernv_add_idle_states(void)
 163 {
 164         struct device_node *power_mgt;
 165         struct property *prop;
 166         int nr_idle_states = 1; /* Snooze */
 167         int dt_idle_states;
 168         u32 *flags;
 169         int i;
 170
 171         /* Currently we have snooze statically defined */
 172
 173         power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
 174         if (!power_mgt) {
 175                 pr_warn("opal: PowerMgmt Node not found\n");
 176                 return nr_idle_states;
 177         }
 178
 179         prop = of_find_property(power_mgt, "ibm,cpu-idle-state-flags", NULL);
 180         if (!prop) {
 181                 pr_warn("DT-PowerMgmt: missing ibm,cpu-idle-state-flags\n");
 182                 return nr_idle_states;
 183         }
 184
 185         dt_idle_states = prop->length / sizeof(u32);
 186         flags = (u32 *) prop->value;
 187
 188         for (i = 0; i < dt_idle_states; i++) {
 189
 190                 if (flags[i] & IDLE_USE_INST_NAP) {
 191                         /* Add NAP state */
 192                         strcpy(powernv_states[nr_idle_states].name, "Nap");
 193                         strcpy(powernv_states[nr_idle_states].desc, "Nap");
 194                         powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIME_VALID;
 195                         powernv_states[nr_idle_states].exit_latency = 10;
 196                         powernv_states[nr_idle_states].target_residency = 100;
 197                         powernv_states[nr_idle_states].enter = &nap_loop;
 198                         nr_idle_states++;
 199                 }
 200
 201                 if (flags[i] & IDLE_USE_INST_SLEEP) {
 202                         /* Add FASTSLEEP state */
 203                         strcpy(powernv_states[nr_idle_states].name, "FastSleep");
 204                         strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
 205                         powernv_states[nr_idle_states].flags =
 206                                 CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TIMER_STOP;
 207                         powernv_states[nr_idle_states].exit_latency = 300;
 208                         powernv_states[nr_idle_states].target_residency = 1000000;
 209                         powernv_states[nr_idle_states].enter = &fastsleep_loop;
 210                         nr_idle_states++;
 211                 }
 212         }
 213
 214         return nr_idle_states;
 215 }
 216
 217 /*
 218  * powernv_idle_probe()
 219  * Choose state table for shared versus dedicated partition
 220  */
 221 static int powernv_idle_probe(void)
 222 {
 223         if (cpuidle_disable != IDLE_NO_OVERRIDE)
 224                 return -ENODEV;
 225
 226         if (firmware_has_feature(FW_FEATURE_OPALv3)) {
 227                 cpuidle_state_table = powernv_states;
 228                 /* Device tree can indicate more idle states */
 229                 max_idle_state = powernv_add_idle_states();
 230         } else
 231                 return -ENODEV;
 232
 233         return 0;
 234 }
 235
 236 static int __init powernv_processor_idle_init(void)
 237 {
 238         int retval;
 239
 240         retval = powernv_idle_probe();
 241         if (retval)
 242                 return retval;
 243
 244         powernv_cpuidle_driver_init();
 245         retval = cpuidle_register(&powernv_idle_driver, NULL);
 246         if (retval) {
 247                 printk(KERN_DEBUG "Registration of powernv driver failed.\n");
 248                 return retval;
 249         }
 250
 251         register_cpu_notifier(&setup_hotplug_notifier);
 252         printk(KERN_DEBUG "powernv_idle_driver registered\n");
 253         return 0;
 254 }
 255
 256 device_initcall(powernv_processor_idle_init);