// SPDX-License-Identifier: GPL-2.0 /* * cpuidle-pseries - idle state cpuidle driver. * Adapted from drivers/idle/intel_idle.c and * drivers/acpi/processor_idle.c * */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include static struct cpuidle_driver pseries_idle_driver = { .name = "pseries_idle", .owner = THIS_MODULE, }; static int max_idle_state __read_mostly; static struct cpuidle_state *cpuidle_state_table __read_mostly; static u64 snooze_timeout __read_mostly; static bool snooze_timeout_en __read_mostly; static int snooze_loop(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { u64 snooze_exit_time; set_thread_flag(TIF_POLLING_NRFLAG); pseries_idle_prolog(); local_irq_enable(); snooze_exit_time = get_tb() + snooze_timeout; while (!need_resched()) { HMT_low(); HMT_very_low(); if (likely(snooze_timeout_en) && get_tb() > snooze_exit_time) { /* * Task has not woken up but we are exiting the polling * loop anyway. Require a barrier after polling is * cleared to order subsequent test of need_resched(). */ clear_thread_flag(TIF_POLLING_NRFLAG); smp_mb(); break; } } HMT_medium(); clear_thread_flag(TIF_POLLING_NRFLAG); local_irq_disable(); pseries_idle_epilog(); return index; } static void check_and_cede_processor(void) { /* * Ensure our interrupt state is properly tracked, * also checks if no interrupt has occurred while we * were soft-disabled */ if (prep_irq_for_idle()) { cede_processor(); #ifdef CONFIG_TRACE_IRQFLAGS /* Ensure that H_CEDE returns with IRQs on */ if (WARN_ON(!(mfmsr() & MSR_EE))) __hard_irq_enable(); #endif } } #define NR_DEDICATED_STATES 2 /* snooze, CEDE */ static u8 cede_latency_hint[NR_DEDICATED_STATES]; static int dedicated_cede_loop(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { u8 old_latency_hint; pseries_idle_prolog(); get_lppaca()->donate_dedicated_cpu = 1; old_latency_hint = get_lppaca()->cede_latency_hint; get_lppaca()->cede_latency_hint = cede_latency_hint[index]; HMT_medium(); check_and_cede_processor(); local_irq_disable(); get_lppaca()->donate_dedicated_cpu = 0; get_lppaca()->cede_latency_hint = old_latency_hint; pseries_idle_epilog(); return index; } static int shared_cede_loop(struct cpuidle_device *dev, struct cpuidle_driver *drv, int index) { pseries_idle_prolog(); /* * Yield the processor to the hypervisor. We return if * an external interrupt occurs (which are driven prior * to returning here) or if a prod occurs from another * processor. When returning here, external interrupts * are enabled. */ check_and_cede_processor(); local_irq_disable(); pseries_idle_epilog(); return index; } /* * States for dedicated partition case. */ static struct cpuidle_state dedicated_states[NR_DEDICATED_STATES] = { { /* Snooze */ .name = "snooze", .desc = "snooze", .exit_latency = 0, .target_residency = 0, .enter = &snooze_loop }, { /* CEDE */ .name = "CEDE", .desc = "CEDE", .exit_latency = 10, .target_residency = 100, .enter = &dedicated_cede_loop }, }; /* * States for shared partition case. */ static struct cpuidle_state shared_states[] = { { /* Snooze */ .name = "snooze", .desc = "snooze", .exit_latency = 0, .target_residency = 0, .enter = &snooze_loop }, { /* Shared Cede */ .name = "Shared Cede", .desc = "Shared Cede", .exit_latency = 10, .target_residency = 100, .enter = &shared_cede_loop }, }; static int pseries_cpuidle_cpu_online(unsigned int cpu) { struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu); if (dev && cpuidle_get_driver()) { cpuidle_pause_and_lock(); cpuidle_enable_device(dev); cpuidle_resume_and_unlock(); } return 0; } static int pseries_cpuidle_cpu_dead(unsigned int cpu) { struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu); if (dev && cpuidle_get_driver()) { cpuidle_pause_and_lock(); cpuidle_disable_device(dev); cpuidle_resume_and_unlock(); } return 0; } /* * pseries_cpuidle_driver_init() */ static int pseries_cpuidle_driver_init(void) { int idle_state; struct cpuidle_driver *drv = &pseries_idle_driver; drv->state_count = 0; for (idle_state = 0; idle_state < max_idle_state; ++idle_state) { /* Is the state not enabled? */ if (cpuidle_state_table[idle_state].enter == NULL) continue; drv->states[drv->state_count] = /* structure copy */ cpuidle_state_table[idle_state]; drv->state_count += 1; } return 0; } /* * pseries_idle_probe() * Choose state table for shared versus dedicated partition */ static int pseries_idle_probe(void) { if (cpuidle_disable != IDLE_NO_OVERRIDE) return -ENODEV; if (firmware_has_feature(FW_FEATURE_SPLPAR)) { /* * Use local_paca instead of get_lppaca() since * preemption is not disabled, and it is not required in * fact, since lppaca_ptr does not need to be the value * associated to the current CPU, it can be from any CPU. */ if (lppaca_shared_proc(local_paca->lppaca_ptr)) { cpuidle_state_table = shared_states; max_idle_state = ARRAY_SIZE(shared_states); } else { cpuidle_state_table = dedicated_states; max_idle_state = NR_DEDICATED_STATES; } } else return -ENODEV; if (max_idle_state > 1) { snooze_timeout_en = true; snooze_timeout = cpuidle_state_table[1].target_residency * tb_ticks_per_usec; } return 0; } static int __init pseries_processor_idle_init(void) { int retval; retval = pseries_idle_probe(); if (retval) return retval; pseries_cpuidle_driver_init(); retval = cpuidle_register(&pseries_idle_driver, NULL); if (retval) { printk(KERN_DEBUG "Registration of pseries driver failed.\n"); return retval; } retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "cpuidle/pseries:online", pseries_cpuidle_cpu_online, NULL); WARN_ON(retval < 0); retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD, "cpuidle/pseries:DEAD", NULL, pseries_cpuidle_cpu_dead); WARN_ON(retval < 0); printk(KERN_DEBUG "pseries_idle_driver registered\n"); return 0; } device_initcall(pseries_processor_idle_init);