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/opal.h>
  20 #include <asm/runlatch.h>
  21
  22 #define MAX_POWERNV_IDLE_STATES 8
  23
  24 struct cpuidle_driver powernv_idle_driver = {
  25         .name             = "powernv_idle",
  26         .owner            = THIS_MODULE,
  27 };
  28
  29 static int max_idle_state;
  30 static struct cpuidle_state *cpuidle_state_table;
  31
  32 static int snooze_loop(struct cpuidle_device *dev,
  33                         struct cpuidle_driver *drv,
  34                         int index)
  35 {
  36         local_irq_enable();
  37         set_thread_flag(TIF_POLLING_NRFLAG);
  38
  39         ppc64_runlatch_off();
  40         while (!need_resched()) {
  41                 HMT_low();
  42                 HMT_very_low();
  43         }
  44
  45         HMT_medium();
  46         ppc64_runlatch_on();
  47         clear_thread_flag(TIF_POLLING_NRFLAG);
  48         smp_mb();
  49         return index;
  50 }
  51
  52 static int nap_loop(struct cpuidle_device *dev,
  53                         struct cpuidle_driver *drv,
  54                         int index)
  55 {
  56         ppc64_runlatch_off();
  57         power7_idle();
  58         ppc64_runlatch_on();
  59         return index;
  60 }
  61
  62 static int fastsleep_loop(struct cpuidle_device *dev,
  63                                 struct cpuidle_driver *drv,
  64                                 int index)
  65 {
  66         unsigned long old_lpcr = mfspr(SPRN_LPCR);
  67         unsigned long new_lpcr;
  68
  69         if (unlikely(system_state < SYSTEM_RUNNING))
  70                 return index;
  71
  72         new_lpcr = old_lpcr;
  73         /* Do not exit powersave upon decrementer as we've setup the timer
  74          * offload.
  75          */
  76         new_lpcr &= ~LPCR_PECE1;
  77
  78         mtspr(SPRN_LPCR, new_lpcr);
  79         power7_sleep();
  80
  81         mtspr(SPRN_LPCR, old_lpcr);
  82
  83         return index;
  84 }
  85
  86 /*
  87  * States for dedicated partition case.
  88  */
  89 static struct cpuidle_state powernv_states[MAX_POWERNV_IDLE_STATES] = {
  90         { /* Snooze */
  91                 .name = "snooze",
  92                 .desc = "snooze",
  93                 .exit_latency = 0,
  94                 .target_residency = 0,
  95                 .enter = &snooze_loop },
  96 };
  97
  98 static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
  99                         unsigned long action, void *hcpu)
 100 {
 101         int hotcpu = (unsigned long)hcpu;
 102         struct cpuidle_device *dev =
 103                                 per_cpu(cpuidle_devices, hotcpu);
 104
 105         if (dev && cpuidle_get_driver()) {
 106                 switch (action) {
 107                 case CPU_ONLINE:
 108                 case CPU_ONLINE_FROZEN:
 109                         cpuidle_pause_and_lock();
 110                         cpuidle_enable_device(dev);
 111                         cpuidle_resume_and_unlock();
 112                         break;
 113
 114                 case CPU_DEAD:
 115                 case CPU_DEAD_FROZEN:
 116                         cpuidle_pause_and_lock();
 117                         cpuidle_disable_device(dev);
 118                         cpuidle_resume_and_unlock();
 119                         break;
 120
 121                 default:
 122                         return NOTIFY_DONE;
 123                 }
 124         }
 125         return NOTIFY_OK;
 126 }
 127
 128 static struct notifier_block setup_hotplug_notifier = {
 129         .notifier_call = powernv_cpuidle_add_cpu_notifier,
 130 };
 131
 132 /*
 133  * powernv_cpuidle_driver_init()
 134  */
 135 static int powernv_cpuidle_driver_init(void)
 136 {
 137         int idle_state;
 138         struct cpuidle_driver *drv = &powernv_idle_driver;
 139
 140         drv->state_count = 0;
 141
 142         for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
 143                 /* Is the state not enabled? */
 144                 if (cpuidle_state_table[idle_state].enter == NULL)
 145                         continue;
 146
 147                 drv->states[drv->state_count] = /* structure copy */
 148                         cpuidle_state_table[idle_state];
 149
 150                 drv->state_count += 1;
 151         }
 152
 153         return 0;
 154 }
 155
 156 static int powernv_add_idle_states(void)
 157 {
 158         struct device_node *power_mgt;
 159         int nr_idle_states = 1; /* Snooze */
 160         int dt_idle_states;
 161         const __be32 *idle_state_flags;
 162         const __be32 *idle_state_latency;
 163         u32 len_flags, flags, latency_ns;
 164         int i;
 165
 166         /* Currently we have snooze statically defined */
 167
 168         power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
 169         if (!power_mgt) {
 170                 pr_warn("opal: PowerMgmt Node not found\n");
 171                 return nr_idle_states;
 172         }
 173
 174         idle_state_flags = of_get_property(power_mgt, "ibm,cpu-idle-state-flags", &len_flags);
 175         if (!idle_state_flags) {
 176                 pr_warn("DT-PowerMgmt: missing ibm,cpu-idle-state-flags\n");
 177                 return nr_idle_states;
 178         }
 179
 180         idle_state_latency = of_get_property(power_mgt,
 181                         "ibm,cpu-idle-state-latencies-ns", NULL);
 182         if (!idle_state_latency) {
 183                 pr_warn("DT-PowerMgmt: missing ibm,cpu-idle-state-latencies-ns\n");
 184                 return nr_idle_states;
 185         }
 186
 187         dt_idle_states = len_flags / sizeof(u32);
 188
 189         for (i = 0; i < dt_idle_states; i++) {
 190
 191                 flags = be32_to_cpu(idle_state_flags[i]);
 192
 193                 /* Cpuidle accepts exit_latency in us and we estimate
 194                  * target residency to be 10x exit_latency
 195                  */
 196                 latency_ns = be32_to_cpu(idle_state_latency[i]);
 197                 if (flags & OPAL_PM_NAP_ENABLED) {
 198                         /* Add NAP state */
 199                         strcpy(powernv_states[nr_idle_states].name, "Nap");
 200                         strcpy(powernv_states[nr_idle_states].desc, "Nap");
 201                         powernv_states[nr_idle_states].flags = 0;
 202                         powernv_states[nr_idle_states].exit_latency =
 203                                         ((unsigned int)latency_ns) / 1000;
 204                         powernv_states[nr_idle_states].target_residency =
 205                                         ((unsigned int)latency_ns / 100);
 206                         powernv_states[nr_idle_states].enter = &nap_loop;
 207                         nr_idle_states++;
 208                 }
 209
 210                 if (flags & OPAL_PM_SLEEP_ENABLED ||
 211                         flags & OPAL_PM_SLEEP_ENABLED_ER1) {
 212                         /* Add FASTSLEEP state */
 213                         strcpy(powernv_states[nr_idle_states].name, "FastSleep");
 214                         strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
 215                         powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIMER_STOP;
 216                         powernv_states[nr_idle_states].exit_latency =
 217                                         ((unsigned int)latency_ns) / 1000;
 218                         powernv_states[nr_idle_states].target_residency =
 219                                         ((unsigned int)latency_ns / 100);
 220                         powernv_states[nr_idle_states].enter = &fastsleep_loop;
 221                         nr_idle_states++;
 222                 }
 223         }
 224
 225         return nr_idle_states;
 226 }
 227
 228 /*
 229  * powernv_idle_probe()
 230  * Choose state table for shared versus dedicated partition
 231  */
 232 static int powernv_idle_probe(void)
 233 {
 234         if (cpuidle_disable != IDLE_NO_OVERRIDE)
 235                 return -ENODEV;
 236
 237         if (firmware_has_feature(FW_FEATURE_OPALv3)) {
 238                 cpuidle_state_table = powernv_states;
 239                 /* Device tree can indicate more idle states */
 240                 max_idle_state = powernv_add_idle_states();
 241         } else
 242                 return -ENODEV;
 243
 244         return 0;
 245 }
 246
 247 static int __init powernv_processor_idle_init(void)
 248 {
 249         int retval;
 250
 251         retval = powernv_idle_probe();
 252         if (retval)
 253                 return retval;
 254
 255         powernv_cpuidle_driver_init();
 256         retval = cpuidle_register(&powernv_idle_driver, NULL);
 257         if (retval) {
 258                 printk(KERN_DEBUG "Registration of powernv driver failed.\n");
 259                 return retval;
 260         }
 261
 262         register_cpu_notifier(&setup_hotplug_notifier);
 263         printk(KERN_DEBUG "powernv_idle_driver registered\n");
 264         return 0;
 265 }
 266
 267 device_initcall(powernv_processor_idle_init);