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         /* Do not exit powersave upon decrementer as we've setup the timer
  77          * offload.
  78          */
  79         new_lpcr &= ~LPCR_PECE1;
  80
  81         mtspr(SPRN_LPCR, new_lpcr);
  82         power7_sleep();
  83
  84         mtspr(SPRN_LPCR, old_lpcr);
  85
  86         return index;
  87 }
  88
  89 /*
  90  * States for dedicated partition case.
  91  */
  92 static struct cpuidle_state powernv_states[MAX_POWERNV_IDLE_STATES] = {
  93         { /* Snooze */
  94                 .name = "snooze",
  95                 .desc = "snooze",
  96                 .flags = CPUIDLE_FLAG_TIME_VALID,
  97                 .exit_latency = 0,
  98                 .target_residency = 0,
  99                 .enter = &snooze_loop },
 100 };
 101
 102 static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
 103                         unsigned long action, void *hcpu)
 104 {
 105         int hotcpu = (unsigned long)hcpu;
 106         struct cpuidle_device *dev =
 107                                 per_cpu(cpuidle_devices, hotcpu);
 108
 109         if (dev && cpuidle_get_driver()) {
 110                 switch (action) {
 111                 case CPU_ONLINE:
 112                 case CPU_ONLINE_FROZEN:
 113                         cpuidle_pause_and_lock();
 114                         cpuidle_enable_device(dev);
 115                         cpuidle_resume_and_unlock();
 116                         break;
 117
 118                 case CPU_DEAD:
 119                 case CPU_DEAD_FROZEN:
 120                         cpuidle_pause_and_lock();
 121                         cpuidle_disable_device(dev);
 122                         cpuidle_resume_and_unlock();
 123                         break;
 124
 125                 default:
 126                         return NOTIFY_DONE;
 127                 }
 128         }
 129         return NOTIFY_OK;
 130 }
 131
 132 static struct notifier_block setup_hotplug_notifier = {
 133         .notifier_call = powernv_cpuidle_add_cpu_notifier,
 134 };
 135
 136 /*
 137  * powernv_cpuidle_driver_init()
 138  */
 139 static int powernv_cpuidle_driver_init(void)
 140 {
 141         int idle_state;
 142         struct cpuidle_driver *drv = &powernv_idle_driver;
 143
 144         drv->state_count = 0;
 145
 146         for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
 147                 /* Is the state not enabled? */
 148                 if (cpuidle_state_table[idle_state].enter == NULL)
 149                         continue;
 150
 151                 drv->states[drv->state_count] = /* structure copy */
 152                         cpuidle_state_table[idle_state];
 153
 154                 drv->state_count += 1;
 155         }
 156
 157         return 0;
 158 }
 159
 160 static int powernv_add_idle_states(void)
 161 {
 162         struct device_node *power_mgt;
 163         int nr_idle_states = 1; /* Snooze */
 164         int dt_idle_states;
 165         const __be32 *idle_state_flags;
 166         const __be32 *idle_state_latency;
 167         u32 len_flags, flags, latency_ns;
 168         int i;
 169
 170         /* Currently we have snooze statically defined */
 171
 172         power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
 173         if (!power_mgt) {
 174                 pr_warn("opal: PowerMgmt Node not found\n");
 175                 return nr_idle_states;
 176         }
 177
 178         idle_state_flags = of_get_property(power_mgt, "ibm,cpu-idle-state-flags", &len_flags);
 179         if (!idle_state_flags) {
 180                 pr_warn("DT-PowerMgmt: missing ibm,cpu-idle-state-flags\n");
 181                 return nr_idle_states;
 182         }
 183
 184         idle_state_latency = of_get_property(power_mgt,
 185                         "ibm,cpu-idle-state-latencies-ns", NULL);
 186         if (!idle_state_latency) {
 187                 pr_warn("DT-PowerMgmt: missing ibm,cpu-idle-state-latencies-ns\n");
 188                 return nr_idle_states;
 189         }
 190
 191         dt_idle_states = len_flags / sizeof(u32);
 192
 193         for (i = 0; i < dt_idle_states; i++) {
 194
 195                 flags = be32_to_cpu(idle_state_flags[i]);
 196
 197                 /* Cpuidle accepts exit_latency in us and we estimate
 198                  * target residency to be 10x exit_latency
 199                  */
 200                 latency_ns = be32_to_cpu(idle_state_latency[i]);
 201                 if (flags & IDLE_USE_INST_NAP) {
 202                         /* Add NAP state */
 203                         strcpy(powernv_states[nr_idle_states].name, "Nap");
 204                         strcpy(powernv_states[nr_idle_states].desc, "Nap");
 205                         powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIME_VALID;
 206                         powernv_states[nr_idle_states].exit_latency =
 207                                         ((unsigned int)latency_ns) / 1000;
 208                         powernv_states[nr_idle_states].target_residency =
 209                                         ((unsigned int)latency_ns / 100);
 210                         powernv_states[nr_idle_states].enter = &nap_loop;
 211                         nr_idle_states++;
 212                 }
 213
 214                 if (flags & IDLE_USE_INST_SLEEP) {
 215                         /* Add FASTSLEEP state */
 216                         strcpy(powernv_states[nr_idle_states].name, "FastSleep");
 217                         strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
 218                         powernv_states[nr_idle_states].flags =
 219                                 CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TIMER_STOP;
 220                         powernv_states[nr_idle_states].exit_latency =
 221                                         ((unsigned int)latency_ns) / 1000;
 222                         powernv_states[nr_idle_states].target_residency =
 223                                         ((unsigned int)latency_ns / 100);
 224                         powernv_states[nr_idle_states].enter = &fastsleep_loop;
 225                         nr_idle_states++;
 226                 }
 227         }
 228
 229         return nr_idle_states;
 230 }
 231
 232 /*
 233  * powernv_idle_probe()
 234  * Choose state table for shared versus dedicated partition
 235  */
 236 static int powernv_idle_probe(void)
 237 {
 238         if (cpuidle_disable != IDLE_NO_OVERRIDE)
 239                 return -ENODEV;
 240
 241         if (firmware_has_feature(FW_FEATURE_OPALv3)) {
 242                 cpuidle_state_table = powernv_states;
 243                 /* Device tree can indicate more idle states */
 244                 max_idle_state = powernv_add_idle_states();
 245         } else
 246                 return -ENODEV;
 247
 248         return 0;
 249 }
 250
 251 static int __init powernv_processor_idle_init(void)
 252 {
 253         int retval;
 254
 255         retval = powernv_idle_probe();
 256         if (retval)
 257                 return retval;
 258
 259         powernv_cpuidle_driver_init();
 260         retval = cpuidle_register(&powernv_idle_driver, NULL);
 261         if (retval) {
 262                 printk(KERN_DEBUG "Registration of powernv driver failed.\n");
 263                 return retval;
 264         }
 265
 266         register_cpu_notifier(&setup_hotplug_notifier);
 267         printk(KERN_DEBUG "powernv_idle_driver registered\n");
 268         return 0;
 269 }
 270
 271 device_initcall(powernv_processor_idle_init);