drivers/cpuidle/cpuidle-powernv.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  cpuidle-powernv - idle state cpuidle driver.
   4  *  Adapted from drivers/cpuidle/cpuidle-pseries
   5  *
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/moduleparam.h>
  12 #include <linux/cpuidle.h>
  13 #include <linux/cpu.h>
  14 #include <linux/notifier.h>
  15 #include <linux/clockchips.h>
  16 #include <linux/of.h>
  17 #include <linux/slab.h>
  18
  19 #include <asm/machdep.h>
  20 #include <asm/firmware.h>
  21 #include <asm/opal.h>
  22 #include <asm/runlatch.h>
  23 #include <asm/cpuidle.h>
  24
  25 /*
  26  * Expose only those Hardware idle states via the cpuidle framework
  27  * that have latency value below POWERNV_THRESHOLD_LATENCY_NS.
  28  */
  29 #define POWERNV_THRESHOLD_LATENCY_NS 200000
  30
  31 static struct cpuidle_driver powernv_idle_driver = {
  32         .name             = "powernv_idle",
  33         .owner            = THIS_MODULE,
  34 };
  35
  36 static int max_idle_state __read_mostly;
  37 static struct cpuidle_state *cpuidle_state_table __read_mostly;
  38
  39 struct stop_psscr_table {
  40         u64 val;
  41         u64 mask;
  42 };
  43
  44 static struct stop_psscr_table stop_psscr_table[CPUIDLE_STATE_MAX] __read_mostly;
  45
  46 static u64 default_snooze_timeout __read_mostly;
  47 static bool snooze_timeout_en __read_mostly;
  48
  49 static u64 get_snooze_timeout(struct cpuidle_device *dev,
  50                               struct cpuidle_driver *drv,
  51                               int index)
  52 {
  53         int i;
  54
  55         if (unlikely(!snooze_timeout_en))
  56                 return default_snooze_timeout;
  57
  58         for (i = index + 1; i < drv->state_count; i++) {
  59                 if (dev->states_usage[i].disable)
  60                         continue;
  61
  62                 return drv->states[i].target_residency * tb_ticks_per_usec;
  63         }
  64
  65         return default_snooze_timeout;
  66 }
  67
  68 static int snooze_loop(struct cpuidle_device *dev,
  69                         struct cpuidle_driver *drv,
  70                         int index)
  71 {
  72         u64 snooze_exit_time;
  73
  74         set_thread_flag(TIF_POLLING_NRFLAG);
  75
  76         local_irq_enable();
  77
  78         snooze_exit_time = get_tb() + get_snooze_timeout(dev, drv, index);
  79         ppc64_runlatch_off();
  80         HMT_very_low();
  81         while (!need_resched()) {
  82                 if (likely(snooze_timeout_en) && get_tb() > snooze_exit_time) {
  83                         /*
  84                          * Task has not woken up but we are exiting the polling
  85                          * loop anyway. Require a barrier after polling is
  86                          * cleared to order subsequent test of need_resched().
  87                          */
  88                         clear_thread_flag(TIF_POLLING_NRFLAG);
  89                         smp_mb();
  90                         break;
  91                 }
  92         }
  93
  94         HMT_medium();
  95         ppc64_runlatch_on();
  96         clear_thread_flag(TIF_POLLING_NRFLAG);
  97
  98         local_irq_disable();
  99
 100         return index;
 101 }
 102
 103 static int nap_loop(struct cpuidle_device *dev,
 104                         struct cpuidle_driver *drv,
 105                         int index)
 106 {
 107         power7_idle_type(PNV_THREAD_NAP);
 108
 109         return index;
 110 }
 111
 112 /* Register for fastsleep only in oneshot mode of broadcast */
 113 #ifdef CONFIG_TICK_ONESHOT
 114 static int fastsleep_loop(struct cpuidle_device *dev,
 115                                 struct cpuidle_driver *drv,
 116                                 int index)
 117 {
 118         unsigned long old_lpcr = mfspr(SPRN_LPCR);
 119         unsigned long new_lpcr;
 120
 121         if (unlikely(system_state < SYSTEM_RUNNING))
 122                 return index;
 123
 124         new_lpcr = old_lpcr;
 125         /* Do not exit powersave upon decrementer as we've setup the timer
 126          * offload.
 127          */
 128         new_lpcr &= ~LPCR_PECE1;
 129
 130         mtspr(SPRN_LPCR, new_lpcr);
 131
 132         power7_idle_type(PNV_THREAD_SLEEP);
 133
 134         mtspr(SPRN_LPCR, old_lpcr);
 135
 136         return index;
 137 }
 138 #endif
 139
 140 static int stop_loop(struct cpuidle_device *dev,
 141                      struct cpuidle_driver *drv,
 142                      int index)
 143 {
 144         arch300_idle_type(stop_psscr_table[index].val,
 145                          stop_psscr_table[index].mask);
 146         return index;
 147 }
 148
 149 /*
 150  * States for dedicated partition case.
 151  */
 152 static struct cpuidle_state powernv_states[CPUIDLE_STATE_MAX] = {
 153         { /* Snooze */
 154                 .name = "snooze",
 155                 .desc = "snooze",
 156                 .exit_latency = 0,
 157                 .target_residency = 0,
 158                 .enter = snooze_loop },
 159 };
 160
 161 static int powernv_cpuidle_cpu_online(unsigned int cpu)
 162 {
 163         struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
 164
 165         if (dev && cpuidle_get_driver()) {
 166                 cpuidle_pause_and_lock();
 167                 cpuidle_enable_device(dev);
 168                 cpuidle_resume_and_unlock();
 169         }
 170         return 0;
 171 }
 172
 173 static int powernv_cpuidle_cpu_dead(unsigned int cpu)
 174 {
 175         struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
 176
 177         if (dev && cpuidle_get_driver()) {
 178                 cpuidle_pause_and_lock();
 179                 cpuidle_disable_device(dev);
 180                 cpuidle_resume_and_unlock();
 181         }
 182         return 0;
 183 }
 184
 185 /*
 186  * powernv_cpuidle_driver_init()
 187  */
 188 static int powernv_cpuidle_driver_init(void)
 189 {
 190         int idle_state;
 191         struct cpuidle_driver *drv = &powernv_idle_driver;
 192
 193         drv->state_count = 0;
 194
 195         for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
 196                 /* Is the state not enabled? */
 197                 if (cpuidle_state_table[idle_state].enter == NULL)
 198                         continue;
 199
 200                 drv->states[drv->state_count] = /* structure copy */
 201                         cpuidle_state_table[idle_state];
 202
 203                 drv->state_count += 1;
 204         }
 205
 206         /*
 207          * On the PowerNV platform cpu_present may be less than cpu_possible in
 208          * cases when firmware detects the CPU, but it is not available to the
 209          * OS.  If CONFIG_HOTPLUG_CPU=n, then such CPUs are not hotplugable at
 210          * run time and hence cpu_devices are not created for those CPUs by the
 211          * generic topology_init().
 212          *
 213          * drv->cpumask defaults to cpu_possible_mask in
 214          * __cpuidle_driver_init().  This breaks cpuidle on PowerNV where
 215          * cpu_devices are not created for CPUs in cpu_possible_mask that
 216          * cannot be hot-added later at run time.
 217          *
 218          * Trying cpuidle_register_device() on a CPU without a cpu_device is
 219          * incorrect, so pass a correct CPU mask to the generic cpuidle driver.
 220          */
 221
 222         drv->cpumask = (struct cpumask *)cpu_present_mask;
 223
 224         return 0;
 225 }
 226
 227 static inline void add_powernv_state(int index, const char *name,
 228                                      unsigned int flags,
 229                                      int (*idle_fn)(struct cpuidle_device *,
 230                                                     struct cpuidle_driver *,
 231                                                     int),
 232                                      unsigned int target_residency,
 233                                      unsigned int exit_latency,
 234                                      u64 psscr_val, u64 psscr_mask)
 235 {
 236         strlcpy(powernv_states[index].name, name, CPUIDLE_NAME_LEN);
 237         strlcpy(powernv_states[index].desc, name, CPUIDLE_NAME_LEN);
 238         powernv_states[index].flags = flags;
 239         powernv_states[index].target_residency = target_residency;
 240         powernv_states[index].exit_latency = exit_latency;
 241         powernv_states[index].enter = idle_fn;
 242         /* For power8 and below psscr_* will be 0 */
 243         stop_psscr_table[index].val = psscr_val;
 244         stop_psscr_table[index].mask = psscr_mask;
 245 }
 246
 247 extern u32 pnv_get_supported_cpuidle_states(void);
 248 static int powernv_add_idle_states(void)
 249 {
 250         int nr_idle_states = 1; /* Snooze */
 251         int dt_idle_states;
 252         u32 has_stop_states = 0;
 253         int i;
 254         u32 supported_flags = pnv_get_supported_cpuidle_states();
 255
 256
 257         /* Currently we have snooze statically defined */
 258         if (nr_pnv_idle_states <= 0) {
 259                 pr_warn("cpuidle-powernv : Only Snooze is available\n");
 260                 goto out;
 261         }
 262
 263         /* TODO: Count only states which are eligible for cpuidle */
 264         dt_idle_states = nr_pnv_idle_states;
 265
 266         /*
 267          * Since snooze is used as first idle state, max idle states allowed is
 268          * CPUIDLE_STATE_MAX -1
 269          */
 270         if (nr_pnv_idle_states > CPUIDLE_STATE_MAX - 1) {
 271                 pr_warn("cpuidle-powernv: discovered idle states more than allowed");
 272                 dt_idle_states = CPUIDLE_STATE_MAX - 1;
 273         }
 274
 275         /*
 276          * If the idle states use stop instruction, probe for psscr values
 277          * and psscr mask which are necessary to specify required stop level.
 278          */
 279         has_stop_states = (pnv_idle_states[0].flags &
 280                            (OPAL_PM_STOP_INST_FAST | OPAL_PM_STOP_INST_DEEP));
 281
 282         for (i = 0; i < dt_idle_states; i++) {
 283                 unsigned int exit_latency, target_residency;
 284                 bool stops_timebase = false;
 285                 struct pnv_idle_states_t *state = &pnv_idle_states[i];
 286
 287                 /*
 288                  * Skip the platform idle state whose flag isn't in
 289                  * the supported_cpuidle_states flag mask.
 290                  */
 291                 if ((state->flags & supported_flags) != state->flags)
 292                         continue;
 293                 /*
 294                  * If an idle state has exit latency beyond
 295                  * POWERNV_THRESHOLD_LATENCY_NS then don't use it
 296                  * in cpu-idle.
 297                  */
 298                 if (state->latency_ns > POWERNV_THRESHOLD_LATENCY_NS)
 299                         continue;
 300                 /*
 301                  * Firmware passes residency and latency values in ns.
 302                  * cpuidle expects it in us.
 303                  */
 304                 exit_latency = DIV_ROUND_UP(state->latency_ns, 1000);
 305                 target_residency = DIV_ROUND_UP(state->residency_ns, 1000);
 306
 307                 if (has_stop_states && !(state->valid))
 308                                 continue;
 309
 310                 if (state->flags & OPAL_PM_TIMEBASE_STOP)
 311                         stops_timebase = true;
 312
 313                 if (state->flags & OPAL_PM_NAP_ENABLED) {
 314                         /* Add NAP state */
 315                         add_powernv_state(nr_idle_states, "Nap",
 316                                           CPUIDLE_FLAG_NONE, nap_loop,
 317                                           target_residency, exit_latency, 0, 0);
 318                 } else if (has_stop_states && !stops_timebase) {
 319                         add_powernv_state(nr_idle_states, state->name,
 320                                           CPUIDLE_FLAG_NONE, stop_loop,
 321                                           target_residency, exit_latency,
 322                                           state->psscr_val,
 323                                           state->psscr_mask);
 324                 }
 325
 326                 /*
 327                  * All cpuidle states with CPUIDLE_FLAG_TIMER_STOP set must come
 328                  * within this config dependency check.
 329                  */
 330 #ifdef CONFIG_TICK_ONESHOT
 331                 else if (state->flags & OPAL_PM_SLEEP_ENABLED ||
 332                          state->flags & OPAL_PM_SLEEP_ENABLED_ER1) {
 333                         /* Add FASTSLEEP state */
 334                         add_powernv_state(nr_idle_states, "FastSleep",
 335                                           CPUIDLE_FLAG_TIMER_STOP,
 336                                           fastsleep_loop,
 337                                           target_residency, exit_latency, 0, 0);
 338                 } else if (has_stop_states && stops_timebase) {
 339                         add_powernv_state(nr_idle_states, state->name,
 340                                           CPUIDLE_FLAG_TIMER_STOP, stop_loop,
 341                                           target_residency, exit_latency,
 342                                           state->psscr_val,
 343                                           state->psscr_mask);
 344                 }
 345 #endif
 346                 else
 347                         continue;
 348                 nr_idle_states++;
 349         }
 350 out:
 351         return nr_idle_states;
 352 }
 353
 354 /*
 355  * powernv_idle_probe()
 356  * Choose state table for shared versus dedicated partition
 357  */
 358 static int powernv_idle_probe(void)
 359 {
 360         if (cpuidle_disable != IDLE_NO_OVERRIDE)
 361                 return -ENODEV;
 362
 363         if (firmware_has_feature(FW_FEATURE_OPAL)) {
 364                 cpuidle_state_table = powernv_states;
 365                 /* Device tree can indicate more idle states */
 366                 max_idle_state = powernv_add_idle_states();
 367                 default_snooze_timeout = TICK_USEC * tb_ticks_per_usec;
 368                 if (max_idle_state > 1)
 369                         snooze_timeout_en = true;
 370         } else
 371                 return -ENODEV;
 372
 373         return 0;
 374 }
 375
 376 static int __init powernv_processor_idle_init(void)
 377 {
 378         int retval;
 379
 380         retval = powernv_idle_probe();
 381         if (retval)
 382                 return retval;
 383
 384         powernv_cpuidle_driver_init();
 385         retval = cpuidle_register(&powernv_idle_driver, NULL);
 386         if (retval) {
 387                 printk(KERN_DEBUG "Registration of powernv driver failed.\n");
 388                 return retval;
 389         }
 390
 391         retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
 392                                            "cpuidle/powernv:online",
 393                                            powernv_cpuidle_cpu_online, NULL);
 394         WARN_ON(retval < 0);
 395         retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD,
 396                                            "cpuidle/powernv:dead", NULL,
 397                                            powernv_cpuidle_cpu_dead);
 398         WARN_ON(retval < 0);
 399         printk(KERN_DEBUG "powernv_idle_driver registered\n");
 400         return 0;
 401 }
 402
 403 device_initcall(powernv_processor_idle_init);