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                 .flags = CPUIDLE_FLAG_TIME_VALID,
  94                 .exit_latency = 0,
  95                 .target_residency = 0,
  96                 .enter = &snooze_loop },
  97 };
  98
  99 static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
 100                         unsigned long action, void *hcpu)
 101 {
 102         int hotcpu = (unsigned long)hcpu;
 103         struct cpuidle_device *dev =
 104                                 per_cpu(cpuidle_devices, hotcpu);
 105
 106         if (dev && cpuidle_get_driver()) {
 107                 switch (action) {
 108                 case CPU_ONLINE:
 109                 case CPU_ONLINE_FROZEN:
 110                         cpuidle_pause_and_lock();
 111                         cpuidle_enable_device(dev);
 112                         cpuidle_resume_and_unlock();
 113                         break;
 114
 115                 case CPU_DEAD:
 116                 case CPU_DEAD_FROZEN:
 117                         cpuidle_pause_and_lock();
 118                         cpuidle_disable_device(dev);
 119                         cpuidle_resume_and_unlock();
 120                         break;
 121
 122                 default:
 123                         return NOTIFY_DONE;
 124                 }
 125         }
 126         return NOTIFY_OK;
 127 }
 128
 129 static struct notifier_block setup_hotplug_notifier = {
 130         .notifier_call = powernv_cpuidle_add_cpu_notifier,
 131 };
 132
 133 /*
 134  * powernv_cpuidle_driver_init()
 135  */
 136 static int powernv_cpuidle_driver_init(void)
 137 {
 138         int idle_state;
 139         struct cpuidle_driver *drv = &powernv_idle_driver;
 140
 141         drv->state_count = 0;
 142
 143         for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
 144                 /* Is the state not enabled? */
 145                 if (cpuidle_state_table[idle_state].enter == NULL)
 146                         continue;
 147
 148                 drv->states[drv->state_count] = /* structure copy */
 149                         cpuidle_state_table[idle_state];
 150
 151                 drv->state_count += 1;
 152         }
 153
 154         return 0;
 155 }
 156
 157 static int powernv_add_idle_states(void)
 158 {
 159         struct device_node *power_mgt;
 160         int nr_idle_states = 1; /* Snooze */
 161         int dt_idle_states;
 162         const __be32 *idle_state_flags;
 163         const __be32 *idle_state_latency;
 164         u32 len_flags, flags, latency_ns;
 165         int i;
 166
 167         /* Currently we have snooze statically defined */
 168
 169         power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
 170         if (!power_mgt) {
 171                 pr_warn("opal: PowerMgmt Node not found\n");
 172                 return nr_idle_states;
 173         }
 174
 175         idle_state_flags = of_get_property(power_mgt, "ibm,cpu-idle-state-flags", &len_flags);
 176         if (!idle_state_flags) {
 177                 pr_warn("DT-PowerMgmt: missing ibm,cpu-idle-state-flags\n");
 178                 return nr_idle_states;
 179         }
 180
 181         idle_state_latency = of_get_property(power_mgt,
 182                         "ibm,cpu-idle-state-latencies-ns", NULL);
 183         if (!idle_state_latency) {
 184                 pr_warn("DT-PowerMgmt: missing ibm,cpu-idle-state-latencies-ns\n");
 185                 return nr_idle_states;
 186         }
 187
 188         dt_idle_states = len_flags / sizeof(u32);
 189
 190         for (i = 0; i < dt_idle_states; i++) {
 191
 192                 flags = be32_to_cpu(idle_state_flags[i]);
 193
 194                 /* Cpuidle accepts exit_latency in us and we estimate
 195                  * target residency to be 10x exit_latency
 196                  */
 197                 latency_ns = be32_to_cpu(idle_state_latency[i]);
 198                 if (flags & OPAL_PM_NAP_ENABLED) {
 199                         /* Add NAP state */
 200                         strcpy(powernv_states[nr_idle_states].name, "Nap");
 201                         strcpy(powernv_states[nr_idle_states].desc, "Nap");
 202                         powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIME_VALID;
 203                         powernv_states[nr_idle_states].exit_latency =
 204                                         ((unsigned int)latency_ns) / 1000;
 205                         powernv_states[nr_idle_states].target_residency =
 206                                         ((unsigned int)latency_ns / 100);
 207                         powernv_states[nr_idle_states].enter = &nap_loop;
 208                         nr_idle_states++;
 209                 }
 210
 211                 if (flags & OPAL_PM_SLEEP_ENABLED ||
 212                         flags & OPAL_PM_SLEEP_ENABLED_ER1) {
 213                         /* Add FASTSLEEP state */
 214                         strcpy(powernv_states[nr_idle_states].name, "FastSleep");
 215                         strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
 216                         powernv_states[nr_idle_states].flags =
 217                                 CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TIMER_STOP;
 218                         powernv_states[nr_idle_states].exit_latency =
 219                                         ((unsigned int)latency_ns) / 1000;
 220                         powernv_states[nr_idle_states].target_residency =
 221                                         ((unsigned int)latency_ns / 100);
 222                         powernv_states[nr_idle_states].enter = &fastsleep_loop;
 223                         nr_idle_states++;
 224                 }
 225         }
 226
 227         return nr_idle_states;
 228 }
 229
 230 /*
 231  * powernv_idle_probe()
 232  * Choose state table for shared versus dedicated partition
 233  */
 234 static int powernv_idle_probe(void)
 235 {
 236         if (cpuidle_disable != IDLE_NO_OVERRIDE)
 237                 return -ENODEV;
 238
 239         if (firmware_has_feature(FW_FEATURE_OPALv3)) {
 240                 cpuidle_state_table = powernv_states;
 241                 /* Device tree can indicate more idle states */
 242                 max_idle_state = powernv_add_idle_states();
 243         } else
 244                 return -ENODEV;
 245
 246         return 0;
 247 }
 248
 249 static int __init powernv_processor_idle_init(void)
 250 {
 251         int retval;
 252
 253         retval = powernv_idle_probe();
 254         if (retval)
 255                 return retval;
 256
 257         powernv_cpuidle_driver_init();
 258         retval = cpuidle_register(&powernv_idle_driver, NULL);
 259         if (retval) {
 260                 printk(KERN_DEBUG "Registration of powernv driver failed.\n");
 261                 return retval;
 262         }
 263
 264         register_cpu_notifier(&setup_hotplug_notifier);
 265         printk(KERN_DEBUG "powernv_idle_driver registered\n");
 266         return 0;
 267 }
 268
 269 device_initcall(powernv_processor_idle_init);