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 #include <linux/slab.h>
  17
  18 #include <asm/machdep.h>
  19 #include <asm/firmware.h>
  20 #include <asm/opal.h>
  21 #include <asm/runlatch.h>
  22
  23 #define MAX_POWERNV_IDLE_STATES 8
  24
  25 struct cpuidle_driver powernv_idle_driver = {
  26         .name             = "powernv_idle",
  27         .owner            = THIS_MODULE,
  28 };
  29
  30 static int max_idle_state;
  31 static struct cpuidle_state *cpuidle_state_table;
  32 static u64 snooze_timeout;
  33 static bool snooze_timeout_en;
  34
  35 static int snooze_loop(struct cpuidle_device *dev,
  36                         struct cpuidle_driver *drv,
  37                         int index)
  38 {
  39         u64 snooze_exit_time;
  40
  41         local_irq_enable();
  42         set_thread_flag(TIF_POLLING_NRFLAG);
  43
  44         snooze_exit_time = get_tb() + snooze_timeout;
  45         ppc64_runlatch_off();
  46         while (!need_resched()) {
  47                 HMT_low();
  48                 HMT_very_low();
  49                 if (snooze_timeout_en && get_tb() > snooze_exit_time)
  50                         break;
  51         }
  52
  53         HMT_medium();
  54         ppc64_runlatch_on();
  55         clear_thread_flag(TIF_POLLING_NRFLAG);
  56         smp_mb();
  57         return index;
  58 }
  59
  60 static int nap_loop(struct cpuidle_device *dev,
  61                         struct cpuidle_driver *drv,
  62                         int index)
  63 {
  64         ppc64_runlatch_off();
  65         power7_idle();
  66         ppc64_runlatch_on();
  67         return index;
  68 }
  69
  70 static int fastsleep_loop(struct cpuidle_device *dev,
  71                                 struct cpuidle_driver *drv,
  72                                 int index)
  73 {
  74         unsigned long old_lpcr = mfspr(SPRN_LPCR);
  75         unsigned long new_lpcr;
  76
  77         if (unlikely(system_state < SYSTEM_RUNNING))
  78                 return index;
  79
  80         new_lpcr = old_lpcr;
  81         /* Do not exit powersave upon decrementer as we've setup the timer
  82          * offload.
  83          */
  84         new_lpcr &= ~LPCR_PECE1;
  85
  86         mtspr(SPRN_LPCR, new_lpcr);
  87         power7_sleep();
  88
  89         mtspr(SPRN_LPCR, old_lpcr);
  90
  91         return index;
  92 }
  93
  94 /*
  95  * States for dedicated partition case.
  96  */
  97 static struct cpuidle_state powernv_states[MAX_POWERNV_IDLE_STATES] = {
  98         { /* Snooze */
  99                 .name = "snooze",
 100                 .desc = "snooze",
 101                 .exit_latency = 0,
 102                 .target_residency = 0,
 103                 .enter = &snooze_loop },
 104 };
 105
 106 static int powernv_cpuidle_add_cpu_notifier(struct notifier_block *n,
 107                         unsigned long action, void *hcpu)
 108 {
 109         int hotcpu = (unsigned long)hcpu;
 110         struct cpuidle_device *dev =
 111                                 per_cpu(cpuidle_devices, hotcpu);
 112
 113         if (dev && cpuidle_get_driver()) {
 114                 switch (action) {
 115                 case CPU_ONLINE:
 116                 case CPU_ONLINE_FROZEN:
 117                         cpuidle_pause_and_lock();
 118                         cpuidle_enable_device(dev);
 119                         cpuidle_resume_and_unlock();
 120                         break;
 121
 122                 case CPU_DEAD:
 123                 case CPU_DEAD_FROZEN:
 124                         cpuidle_pause_and_lock();
 125                         cpuidle_disable_device(dev);
 126                         cpuidle_resume_and_unlock();
 127                         break;
 128
 129                 default:
 130                         return NOTIFY_DONE;
 131                 }
 132         }
 133         return NOTIFY_OK;
 134 }
 135
 136 static struct notifier_block setup_hotplug_notifier = {
 137         .notifier_call = powernv_cpuidle_add_cpu_notifier,
 138 };
 139
 140 /*
 141  * powernv_cpuidle_driver_init()
 142  */
 143 static int powernv_cpuidle_driver_init(void)
 144 {
 145         int idle_state;
 146         struct cpuidle_driver *drv = &powernv_idle_driver;
 147
 148         drv->state_count = 0;
 149
 150         for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
 151                 /* Is the state not enabled? */
 152                 if (cpuidle_state_table[idle_state].enter == NULL)
 153                         continue;
 154
 155                 drv->states[drv->state_count] = /* structure copy */
 156                         cpuidle_state_table[idle_state];
 157
 158                 drv->state_count += 1;
 159         }
 160
 161         return 0;
 162 }
 163
 164 static int powernv_add_idle_states(void)
 165 {
 166         struct device_node *power_mgt;
 167         int nr_idle_states = 1; /* Snooze */
 168         int dt_idle_states;
 169         u32 *latency_ns, *residency_ns, *flags;
 170         int i, rc;
 171
 172         /* Currently we have snooze statically defined */
 173
 174         power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
 175         if (!power_mgt) {
 176                 pr_warn("opal: PowerMgmt Node not found\n");
 177                 goto out;
 178         }
 179
 180         /* Read values of any property to determine the num of idle states */
 181         dt_idle_states = of_property_count_u32_elems(power_mgt, "ibm,cpu-idle-state-flags");
 182         if (dt_idle_states < 0) {
 183                 pr_warn("cpuidle-powernv: no idle states found in the DT\n");
 184                 goto out;
 185         }
 186
 187         flags = kzalloc(sizeof(*flags) * dt_idle_states, GFP_KERNEL);
 188         if (of_property_read_u32_array(power_mgt,
 189                         "ibm,cpu-idle-state-flags", flags, dt_idle_states)) {
 190                 pr_warn("cpuidle-powernv : missing ibm,cpu-idle-state-flags in DT\n");
 191                 goto out_free_flags;
 192         }
 193
 194         latency_ns = kzalloc(sizeof(*latency_ns) * dt_idle_states, GFP_KERNEL);
 195         rc = of_property_read_u32_array(power_mgt,
 196                 "ibm,cpu-idle-state-latencies-ns", latency_ns, dt_idle_states);
 197         if (rc) {
 198                 pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-latencies-ns in DT\n");
 199                 goto out_free_latency;
 200         }
 201
 202         residency_ns = kzalloc(sizeof(*residency_ns) * dt_idle_states, GFP_KERNEL);
 203         rc = of_property_read_u32_array(power_mgt,
 204                 "ibm,cpu-idle-state-residency-ns", residency_ns, dt_idle_states);
 205
 206         for (i = 0; i < dt_idle_states; i++) {
 207
 208                 /*
 209                  * Cpuidle accepts exit_latency and target_residency in us.
 210                  * Use default target_residency values if f/w does not expose it.
 211                  */
 212                 if (flags[i] & OPAL_PM_NAP_ENABLED) {
 213                         /* Add NAP state */
 214                         strcpy(powernv_states[nr_idle_states].name, "Nap");
 215                         strcpy(powernv_states[nr_idle_states].desc, "Nap");
 216                         powernv_states[nr_idle_states].flags = 0;
 217                         powernv_states[nr_idle_states].target_residency = 100;
 218                         powernv_states[nr_idle_states].enter = &nap_loop;
 219                 } else if (flags[i] & OPAL_PM_SLEEP_ENABLED ||
 220                         flags[i] & OPAL_PM_SLEEP_ENABLED_ER1) {
 221                         /* Add FASTSLEEP state */
 222                         strcpy(powernv_states[nr_idle_states].name, "FastSleep");
 223                         strcpy(powernv_states[nr_idle_states].desc, "FastSleep");
 224                         powernv_states[nr_idle_states].flags = CPUIDLE_FLAG_TIMER_STOP;
 225                         powernv_states[nr_idle_states].target_residency = 300000;
 226                         powernv_states[nr_idle_states].enter = &fastsleep_loop;
 227                 }
 228
 229                 powernv_states[nr_idle_states].exit_latency =
 230                                 ((unsigned int)latency_ns[i]) / 1000;
 231
 232                 if (!rc) {
 233                         powernv_states[nr_idle_states].target_residency =
 234                                 ((unsigned int)residency_ns[i]) / 1000;
 235                 }
 236
 237                 nr_idle_states++;
 238         }
 239
 240         kfree(residency_ns);
 241 out_free_latency:
 242         kfree(latency_ns);
 243 out_free_flags:
 244         kfree(flags);
 245 out:
 246         return nr_idle_states;
 247 }
 248
 249 /*
 250  * powernv_idle_probe()
 251  * Choose state table for shared versus dedicated partition
 252  */
 253 static int powernv_idle_probe(void)
 254 {
 255         if (cpuidle_disable != IDLE_NO_OVERRIDE)
 256                 return -ENODEV;
 257
 258         if (firmware_has_feature(FW_FEATURE_OPALv3)) {
 259                 cpuidle_state_table = powernv_states;
 260                 /* Device tree can indicate more idle states */
 261                 max_idle_state = powernv_add_idle_states();
 262                 if (max_idle_state > 1) {
 263                         snooze_timeout_en = true;
 264                         snooze_timeout = powernv_states[1].target_residency *
 265                                          tb_ticks_per_usec;
 266                 }
 267         } else
 268                 return -ENODEV;
 269
 270         return 0;
 271 }
 272
 273 static int __init powernv_processor_idle_init(void)
 274 {
 275         int retval;
 276
 277         retval = powernv_idle_probe();
 278         if (retval)
 279                 return retval;
 280
 281         powernv_cpuidle_driver_init();
 282         retval = cpuidle_register(&powernv_idle_driver, NULL);
 283         if (retval) {
 284                 printk(KERN_DEBUG "Registration of powernv driver failed.\n");
 285                 return retval;
 286         }
 287
 288         register_cpu_notifier(&setup_hotplug_notifier);
 289         printk(KERN_DEBUG "powernv_idle_driver registered\n");
 290         return 0;
 291 }
 292
 293 device_initcall(powernv_processor_idle_init);