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         dev->poll_time_limit = false;
  80         ppc64_runlatch_off();
  81         HMT_very_low();
  82         while (!need_resched()) {
  83                 if (likely(snooze_timeout_en) && get_tb() > snooze_exit_time) {
  84                         /*
  85                          * Task has not woken up but we are exiting the polling
  86                          * loop anyway. Require a barrier after polling is
  87                          * cleared to order subsequent test of need_resched().
  88                          */
  89                         clear_thread_flag(TIF_POLLING_NRFLAG);
  90                         dev->poll_time_limit = true;
  91                         smp_mb();
  92                         break;
  93                 }
  94         }
  95
  96         HMT_medium();
  97         ppc64_runlatch_on();
  98         clear_thread_flag(TIF_POLLING_NRFLAG);
  99
 100         local_irq_disable();
 101
 102         return index;
 103 }
 104
 105 static int nap_loop(struct cpuidle_device *dev,
 106                         struct cpuidle_driver *drv,
 107                         int index)
 108 {
 109         power7_idle_type(PNV_THREAD_NAP);
 110
 111         return index;
 112 }
 113
 114 /* Register for fastsleep only in oneshot mode of broadcast */
 115 #ifdef CONFIG_TICK_ONESHOT
 116 static int fastsleep_loop(struct cpuidle_device *dev,
 117                                 struct cpuidle_driver *drv,
 118                                 int index)
 119 {
 120         unsigned long old_lpcr = mfspr(SPRN_LPCR);
 121         unsigned long new_lpcr;
 122
 123         if (unlikely(system_state < SYSTEM_RUNNING))
 124                 return index;
 125
 126         new_lpcr = old_lpcr;
 127         /* Do not exit powersave upon decrementer as we've setup the timer
 128          * offload.
 129          */
 130         new_lpcr &= ~LPCR_PECE1;
 131
 132         mtspr(SPRN_LPCR, new_lpcr);
 133
 134         power7_idle_type(PNV_THREAD_SLEEP);
 135
 136         mtspr(SPRN_LPCR, old_lpcr);
 137
 138         return index;
 139 }
 140 #endif
 141
 142 static int stop_loop(struct cpuidle_device *dev,
 143                      struct cpuidle_driver *drv,
 144                      int index)
 145 {
 146         arch300_idle_type(stop_psscr_table[index].val,
 147                          stop_psscr_table[index].mask);
 148         return index;
 149 }
 150
 151 /*
 152  * States for dedicated partition case.
 153  */
 154 static struct cpuidle_state powernv_states[CPUIDLE_STATE_MAX] = {
 155         { /* Snooze */
 156                 .name = "snooze",
 157                 .desc = "snooze",
 158                 .exit_latency = 0,
 159                 .target_residency = 0,
 160                 .enter = snooze_loop,
 161                 .flags = CPUIDLE_FLAG_POLLING },
 162 };
 163
 164 static int powernv_cpuidle_cpu_online(unsigned int cpu)
 165 {
 166         struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
 167
 168         if (dev && cpuidle_get_driver()) {
 169                 cpuidle_pause_and_lock();
 170                 cpuidle_enable_device(dev);
 171                 cpuidle_resume_and_unlock();
 172         }
 173         return 0;
 174 }
 175
 176 static int powernv_cpuidle_cpu_dead(unsigned int cpu)
 177 {
 178         struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
 179
 180         if (dev && cpuidle_get_driver()) {
 181                 cpuidle_pause_and_lock();
 182                 cpuidle_disable_device(dev);
 183                 cpuidle_resume_and_unlock();
 184         }
 185         return 0;
 186 }
 187
 188 /*
 189  * powernv_cpuidle_driver_init()
 190  */
 191 static int powernv_cpuidle_driver_init(void)
 192 {
 193         int idle_state;
 194         struct cpuidle_driver *drv = &powernv_idle_driver;
 195
 196         drv->state_count = 0;
 197
 198         for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {
 199                 /* Is the state not enabled? */
 200                 if (cpuidle_state_table[idle_state].enter == NULL)
 201                         continue;
 202
 203                 drv->states[drv->state_count] = /* structure copy */
 204                         cpuidle_state_table[idle_state];
 205
 206                 drv->state_count += 1;
 207         }
 208
 209         /*
 210          * On the PowerNV platform cpu_present may be less than cpu_possible in
 211          * cases when firmware detects the CPU, but it is not available to the
 212          * OS.  If CONFIG_HOTPLUG_CPU=n, then such CPUs are not hotplugable at
 213          * run time and hence cpu_devices are not created for those CPUs by the
 214          * generic topology_init().
 215          *
 216          * drv->cpumask defaults to cpu_possible_mask in
 217          * __cpuidle_driver_init().  This breaks cpuidle on PowerNV where
 218          * cpu_devices are not created for CPUs in cpu_possible_mask that
 219          * cannot be hot-added later at run time.
 220          *
 221          * Trying cpuidle_register_device() on a CPU without a cpu_device is
 222          * incorrect, so pass a correct CPU mask to the generic cpuidle driver.
 223          */
 224
 225         drv->cpumask = (struct cpumask *)cpu_present_mask;
 226
 227         return 0;
 228 }
 229
 230 static inline void add_powernv_state(int index, const char *name,
 231                                      unsigned int flags,
 232                                      int (*idle_fn)(struct cpuidle_device *,
 233                                                     struct cpuidle_driver *,
 234                                                     int),
 235                                      unsigned int target_residency,
 236                                      unsigned int exit_latency,
 237                                      u64 psscr_val, u64 psscr_mask)
 238 {
 239         strscpy(powernv_states[index].name, name, CPUIDLE_NAME_LEN);
 240         strscpy(powernv_states[index].desc, name, CPUIDLE_NAME_LEN);
 241         powernv_states[index].flags = flags;
 242         powernv_states[index].target_residency = target_residency;
 243         powernv_states[index].exit_latency = exit_latency;
 244         powernv_states[index].enter = idle_fn;
 245         /* For power8 and below psscr_* will be 0 */
 246         stop_psscr_table[index].val = psscr_val;
 247         stop_psscr_table[index].mask = psscr_mask;
 248 }
 249
 250 extern u32 pnv_get_supported_cpuidle_states(void);
 251 static int powernv_add_idle_states(void)
 252 {
 253         int nr_idle_states = 1; /* Snooze */
 254         int dt_idle_states;
 255         u32 has_stop_states = 0;
 256         int i;
 257         u32 supported_flags = pnv_get_supported_cpuidle_states();
 258
 259
 260         /* Currently we have snooze statically defined */
 261         if (nr_pnv_idle_states <= 0) {
 262                 pr_warn("cpuidle-powernv : Only Snooze is available\n");
 263                 goto out;
 264         }
 265
 266         /* TODO: Count only states which are eligible for cpuidle */
 267         dt_idle_states = nr_pnv_idle_states;
 268
 269         /*
 270          * Since snooze is used as first idle state, max idle states allowed is
 271          * CPUIDLE_STATE_MAX -1
 272          */
 273         if (nr_pnv_idle_states > CPUIDLE_STATE_MAX - 1) {
 274                 pr_warn("cpuidle-powernv: discovered idle states more than allowed");
 275                 dt_idle_states = CPUIDLE_STATE_MAX - 1;
 276         }
 277
 278         /*
 279          * If the idle states use stop instruction, probe for psscr values
 280          * and psscr mask which are necessary to specify required stop level.
 281          */
 282         has_stop_states = (pnv_idle_states[0].flags &
 283                            (OPAL_PM_STOP_INST_FAST | OPAL_PM_STOP_INST_DEEP));
 284
 285         for (i = 0; i < dt_idle_states; i++) {
 286                 unsigned int exit_latency, target_residency;
 287                 bool stops_timebase = false;
 288                 struct pnv_idle_states_t *state = &pnv_idle_states[i];
 289
 290                 /*
 291                  * Skip the platform idle state whose flag isn't in
 292                  * the supported_cpuidle_states flag mask.
 293                  */
 294                 if ((state->flags & supported_flags) != state->flags)
 295                         continue;
 296                 /*
 297                  * If an idle state has exit latency beyond
 298                  * POWERNV_THRESHOLD_LATENCY_NS then don't use it
 299                  * in cpu-idle.
 300                  */
 301                 if (state->latency_ns > POWERNV_THRESHOLD_LATENCY_NS)
 302                         continue;
 303                 /*
 304                  * Firmware passes residency and latency values in ns.
 305                  * cpuidle expects it in us.
 306                  */
 307                 exit_latency = DIV_ROUND_UP(state->latency_ns, 1000);
 308                 target_residency = DIV_ROUND_UP(state->residency_ns, 1000);
 309
 310                 if (has_stop_states && !(state->valid))
 311                                 continue;
 312
 313                 if (state->flags & OPAL_PM_TIMEBASE_STOP)
 314                         stops_timebase = true;
 315
 316                 if (state->flags & OPAL_PM_NAP_ENABLED) {
 317                         /* Add NAP state */
 318                         add_powernv_state(nr_idle_states, "Nap",
 319                                           CPUIDLE_FLAG_NONE, nap_loop,
 320                                           target_residency, exit_latency, 0, 0);
 321                 } else if (has_stop_states && !stops_timebase) {
 322                         add_powernv_state(nr_idle_states, state->name,
 323                                           CPUIDLE_FLAG_NONE, stop_loop,
 324                                           target_residency, exit_latency,
 325                                           state->psscr_val,
 326                                           state->psscr_mask);
 327                 }
 328
 329                 /*
 330                  * All cpuidle states with CPUIDLE_FLAG_TIMER_STOP set must come
 331                  * within this config dependency check.
 332                  */
 333 #ifdef CONFIG_TICK_ONESHOT
 334                 else if (state->flags & OPAL_PM_SLEEP_ENABLED ||
 335                          state->flags & OPAL_PM_SLEEP_ENABLED_ER1) {
 336                         /* Add FASTSLEEP state */
 337                         add_powernv_state(nr_idle_states, "FastSleep",
 338                                           CPUIDLE_FLAG_TIMER_STOP,
 339                                           fastsleep_loop,
 340                                           target_residency, exit_latency, 0, 0);
 341                 } else if (has_stop_states && stops_timebase) {
 342                         add_powernv_state(nr_idle_states, state->name,
 343                                           CPUIDLE_FLAG_TIMER_STOP, stop_loop,
 344                                           target_residency, exit_latency,
 345                                           state->psscr_val,
 346                                           state->psscr_mask);
 347                 }
 348 #endif
 349                 else
 350                         continue;
 351                 nr_idle_states++;
 352         }
 353 out:
 354         return nr_idle_states;
 355 }
 356
 357 /*
 358  * powernv_idle_probe()
 359  * Choose state table for shared versus dedicated partition
 360  */
 361 static int powernv_idle_probe(void)
 362 {
 363         if (cpuidle_disable != IDLE_NO_OVERRIDE)
 364                 return -ENODEV;
 365
 366         if (firmware_has_feature(FW_FEATURE_OPAL)) {
 367                 cpuidle_state_table = powernv_states;
 368                 /* Device tree can indicate more idle states */
 369                 max_idle_state = powernv_add_idle_states();
 370                 default_snooze_timeout = TICK_USEC * tb_ticks_per_usec;
 371                 if (max_idle_state > 1)
 372                         snooze_timeout_en = true;
 373         } else
 374                 return -ENODEV;
 375
 376         return 0;
 377 }
 378
 379 static int __init powernv_processor_idle_init(void)
 380 {
 381         int retval;
 382
 383         retval = powernv_idle_probe();
 384         if (retval)
 385                 return retval;
 386
 387         powernv_cpuidle_driver_init();
 388         retval = cpuidle_register(&powernv_idle_driver, NULL);
 389         if (retval) {
 390                 printk(KERN_DEBUG "Registration of powernv driver failed.\n");
 391                 return retval;
 392         }
 393
 394         retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
 395                                            "cpuidle/powernv:online",
 396                                            powernv_cpuidle_cpu_online, NULL);
 397         WARN_ON(retval < 0);
 398         retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD,
 399                                            "cpuidle/powernv:dead", NULL,
 400                                            powernv_cpuidle_cpu_dead);
 401         WARN_ON(retval < 0);
 402         printk(KERN_DEBUG "powernv_idle_driver registered\n");
 403         return 0;
 404 }
 405
 406 device_initcall(powernv_processor_idle_init);