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); 407