root/drivers/cpuidle/cpuidle-powernv.c

DEFINITIONS

1. get_snooze_timeout
2. snooze_loop
3. nap_loop
4. fastsleep_loop
5. stop_loop
6. powernv_cpuidle_cpu_online
7. powernv_cpuidle_cpu_dead
8. powernv_cpuidle_driver_init
9. add_powernv_state
10. validate_dt_prop_sizes
11. powernv_add_idle_states
12. powernv_idle_probe
13. powernv_processor_idle_init

   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                 struct cpuidle_state *s = &drv->states[i];
  60                 struct cpuidle_state_usage *su = &dev->states_usage[i];
  61 
  62                 if (s->disabled || su->disable)
  63                         continue;
  64 
  65                 return s->target_residency * tb_ticks_per_usec;
  66         }
  67 
  68         return default_snooze_timeout;
  69 }
  70 
  71 static int snooze_loop(struct cpuidle_device *dev,
  72                         struct cpuidle_driver *drv,
  73                         int index)
  74 {
  75         u64 snooze_exit_time;
  76 
  77         set_thread_flag(TIF_POLLING_NRFLAG);
  78 
  79         local_irq_enable();
  80 
  81         snooze_exit_time = get_tb() + get_snooze_timeout(dev, drv, index);
  82         ppc64_runlatch_off();
  83         HMT_very_low();
  84         while (!need_resched()) {
  85                 if (likely(snooze_timeout_en) && get_tb() > snooze_exit_time) {
  86                         /*
  87                          * Task has not woken up but we are exiting the polling
  88                          * loop anyway. Require a barrier after polling is
  89                          * cleared to order subsequent test of need_resched().
  90                          */
  91                         clear_thread_flag(TIF_POLLING_NRFLAG);
  92                         smp_mb();
  93                         break;
  94                 }
  95         }
  96 
  97         HMT_medium();
  98         ppc64_runlatch_on();
  99         clear_thread_flag(TIF_POLLING_NRFLAG);
 100 
 101         local_irq_disable();
 102 
 103         return index;
 104 }
 105 
 106 static int nap_loop(struct cpuidle_device *dev,
 107                         struct cpuidle_driver *drv,
 108                         int index)
 109 {
 110         power7_idle_type(PNV_THREAD_NAP);
 111 
 112         return index;
 113 }
 114 
 115 /* Register for fastsleep only in oneshot mode of broadcast */
 116 #ifdef CONFIG_TICK_ONESHOT
 117 static int fastsleep_loop(struct cpuidle_device *dev,
 118                                 struct cpuidle_driver *drv,
 119                                 int index)
 120 {
 121         unsigned long old_lpcr = mfspr(SPRN_LPCR);
 122         unsigned long new_lpcr;
 123 
 124         if (unlikely(system_state < SYSTEM_RUNNING))
 125                 return index;
 126 
 127         new_lpcr = old_lpcr;
 128         /* Do not exit powersave upon decrementer as we've setup the timer
 129          * offload.
 130          */
 131         new_lpcr &= ~LPCR_PECE1;
 132 
 133         mtspr(SPRN_LPCR, new_lpcr);
 134 
 135         power7_idle_type(PNV_THREAD_SLEEP);
 136 
 137         mtspr(SPRN_LPCR, old_lpcr);
 138 
 139         return index;
 140 }
 141 #endif
 142 
 143 static int stop_loop(struct cpuidle_device *dev,
 144                      struct cpuidle_driver *drv,
 145                      int index)
 146 {
 147         power9_idle_type(stop_psscr_table[index].val,
 148                          stop_psscr_table[index].mask);
 149         return index;
 150 }
 151 
 152 /*
 153  * States for dedicated partition case.
 154  */
 155 static struct cpuidle_state powernv_states[CPUIDLE_STATE_MAX] = {
 156         { /* Snooze */
 157                 .name = "snooze",
 158                 .desc = "snooze",
 159                 .exit_latency = 0,
 160                 .target_residency = 0,
 161                 .enter = snooze_loop },
 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         strlcpy(powernv_states[index].name, name, CPUIDLE_NAME_LEN);
 240         strlcpy(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 /*
 251  * Returns 0 if prop1_len == prop2_len. Else returns -1
 252  */
 253 static inline int validate_dt_prop_sizes(const char *prop1, int prop1_len,
 254                                          const char *prop2, int prop2_len)
 255 {
 256         if (prop1_len == prop2_len)
 257                 return 0;
 258 
 259         pr_warn("cpuidle-powernv: array sizes don't match for %s and %s\n",
 260                 prop1, prop2);
 261         return -1;
 262 }
 263 
 264 extern u32 pnv_get_supported_cpuidle_states(void);
 265 static int powernv_add_idle_states(void)
 266 {
 267         int nr_idle_states = 1; /* Snooze */
 268         int dt_idle_states;
 269         u32 has_stop_states = 0;
 270         int i;
 271         u32 supported_flags = pnv_get_supported_cpuidle_states();
 272 
 273 
 274         /* Currently we have snooze statically defined */
 275         if (nr_pnv_idle_states <= 0) {
 276                 pr_warn("cpuidle-powernv : Only Snooze is available\n");
 277                 goto out;
 278         }
 279 
 280         /* TODO: Count only states which are eligible for cpuidle */
 281         dt_idle_states = nr_pnv_idle_states;
 282 
 283         /*
 284          * Since snooze is used as first idle state, max idle states allowed is
 285          * CPUIDLE_STATE_MAX -1
 286          */
 287         if (nr_pnv_idle_states > CPUIDLE_STATE_MAX - 1) {
 288                 pr_warn("cpuidle-powernv: discovered idle states more than allowed");
 289                 dt_idle_states = CPUIDLE_STATE_MAX - 1;
 290         }
 291 
 292         /*
 293          * If the idle states use stop instruction, probe for psscr values
 294          * and psscr mask which are necessary to specify required stop level.
 295          */
 296         has_stop_states = (pnv_idle_states[0].flags &
 297                            (OPAL_PM_STOP_INST_FAST | OPAL_PM_STOP_INST_DEEP));
 298 
 299         for (i = 0; i < dt_idle_states; i++) {
 300                 unsigned int exit_latency, target_residency;
 301                 bool stops_timebase = false;
 302                 struct pnv_idle_states_t *state = &pnv_idle_states[i];
 303 
 304                 /*
 305                  * Skip the platform idle state whose flag isn't in
 306                  * the supported_cpuidle_states flag mask.
 307                  */
 308                 if ((state->flags & supported_flags) != state->flags)
 309                         continue;
 310                 /*
 311                  * If an idle state has exit latency beyond
 312                  * POWERNV_THRESHOLD_LATENCY_NS then don't use it
 313                  * in cpu-idle.
 314                  */
 315                 if (state->latency_ns > POWERNV_THRESHOLD_LATENCY_NS)
 316                         continue;
 317                 /*
 318                  * Firmware passes residency and latency values in ns.
 319                  * cpuidle expects it in us.
 320                  */
 321                 exit_latency = DIV_ROUND_UP(state->latency_ns, 1000);
 322                 target_residency = DIV_ROUND_UP(state->residency_ns, 1000);
 323 
 324                 if (has_stop_states && !(state->valid))
 325                                 continue;
 326 
 327                 if (state->flags & OPAL_PM_TIMEBASE_STOP)
 328                         stops_timebase = true;
 329 
 330                 if (state->flags & OPAL_PM_NAP_ENABLED) {
 331                         /* Add NAP state */
 332                         add_powernv_state(nr_idle_states, "Nap",
 333                                           CPUIDLE_FLAG_NONE, nap_loop,
 334                                           target_residency, exit_latency, 0, 0);
 335                 } else if (has_stop_states && !stops_timebase) {
 336                         add_powernv_state(nr_idle_states, state->name,
 337                                           CPUIDLE_FLAG_NONE, stop_loop,
 338                                           target_residency, exit_latency,
 339                                           state->psscr_val,
 340                                           state->psscr_mask);
 341                 }
 342 
 343                 /*
 344                  * All cpuidle states with CPUIDLE_FLAG_TIMER_STOP set must come
 345                  * within this config dependency check.
 346                  */
 347 #ifdef CONFIG_TICK_ONESHOT
 348                 else if (state->flags & OPAL_PM_SLEEP_ENABLED ||
 349                          state->flags & OPAL_PM_SLEEP_ENABLED_ER1) {
 350                         /* Add FASTSLEEP state */
 351                         add_powernv_state(nr_idle_states, "FastSleep",
 352                                           CPUIDLE_FLAG_TIMER_STOP,
 353                                           fastsleep_loop,
 354                                           target_residency, exit_latency, 0, 0);
 355                 } else if (has_stop_states && stops_timebase) {
 356                         add_powernv_state(nr_idle_states, state->name,
 357                                           CPUIDLE_FLAG_TIMER_STOP, stop_loop,
 358                                           target_residency, exit_latency,
 359                                           state->psscr_val,
 360                                           state->psscr_mask);
 361                 }
 362 #endif
 363                 else
 364                         continue;
 365                 nr_idle_states++;
 366         }
 367 out:
 368         return nr_idle_states;
 369 }
 370 
 371 /*
 372  * powernv_idle_probe()
 373  * Choose state table for shared versus dedicated partition
 374  */
 375 static int powernv_idle_probe(void)
 376 {
 377         if (cpuidle_disable != IDLE_NO_OVERRIDE)
 378                 return -ENODEV;
 379 
 380         if (firmware_has_feature(FW_FEATURE_OPAL)) {
 381                 cpuidle_state_table = powernv_states;
 382                 /* Device tree can indicate more idle states */
 383                 max_idle_state = powernv_add_idle_states();
 384                 default_snooze_timeout = TICK_USEC * tb_ticks_per_usec;
 385                 if (max_idle_state > 1)
 386                         snooze_timeout_en = true;
 387         } else
 388                 return -ENODEV;
 389 
 390         return 0;
 391 }
 392 
 393 static int __init powernv_processor_idle_init(void)
 394 {
 395         int retval;
 396 
 397         retval = powernv_idle_probe();
 398         if (retval)
 399                 return retval;
 400 
 401         powernv_cpuidle_driver_init();
 402         retval = cpuidle_register(&powernv_idle_driver, NULL);
 403         if (retval) {
 404                 printk(KERN_DEBUG "Registration of powernv driver failed.\n");
 405                 return retval;
 406         }
 407 
 408         retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
 409                                            "cpuidle/powernv:online",
 410                                            powernv_cpuidle_cpu_online, NULL);
 411         WARN_ON(retval < 0);
 412         retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD,
 413                                            "cpuidle/powernv:dead", NULL,
 414                                            powernv_cpuidle_cpu_dead);
 415         WARN_ON(retval < 0);
 416         printk(KERN_DEBUG "powernv_idle_driver registered\n");
 417         return 0;
 418 }
 419 
 420 device_initcall(powernv_processor_idle_init);