| // 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 <linux/kernel.h> |
| #include <linux/module.h> |
| #include <linux/init.h> |
| #include <linux/moduleparam.h> |
| #include <linux/cpuidle.h> |
| #include <linux/cpu.h> |
| #include <linux/notifier.h> |
| |
| #include <asm/paca.h> |
| #include <asm/reg.h> |
| #include <asm/machdep.h> |
| #include <asm/firmware.h> |
| #include <asm/runlatch.h> |
| #include <asm/plpar_wrappers.h> |
| |
| 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 inline void idle_loop_prolog(unsigned long *in_purr) |
| { |
| ppc64_runlatch_off(); |
| *in_purr = mfspr(SPRN_PURR); |
| /* |
| * Indicate to the HV that we are idle. Now would be |
| * a good time to find other work to dispatch. |
| */ |
| get_lppaca()->idle = 1; |
| } |
| |
| static inline void idle_loop_epilog(unsigned long in_purr) |
| { |
| u64 wait_cycles; |
| |
| wait_cycles = be64_to_cpu(get_lppaca()->wait_state_cycles); |
| wait_cycles += mfspr(SPRN_PURR) - in_purr; |
| get_lppaca()->wait_state_cycles = cpu_to_be64(wait_cycles); |
| get_lppaca()->idle = 0; |
| |
| ppc64_runlatch_on(); |
| } |
| |
| static int snooze_loop(struct cpuidle_device *dev, |
| struct cpuidle_driver *drv, |
| int index) |
| { |
| unsigned long in_purr; |
| u64 snooze_exit_time; |
| |
| set_thread_flag(TIF_POLLING_NRFLAG); |
| |
| idle_loop_prolog(&in_purr); |
| 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(); |
| |
| idle_loop_epilog(in_purr); |
| |
| 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 |
| } |
| } |
| |
| static int dedicated_cede_loop(struct cpuidle_device *dev, |
| struct cpuidle_driver *drv, |
| int index) |
| { |
| unsigned long in_purr; |
| |
| idle_loop_prolog(&in_purr); |
| get_lppaca()->donate_dedicated_cpu = 1; |
| |
| HMT_medium(); |
| check_and_cede_processor(); |
| |
| local_irq_disable(); |
| get_lppaca()->donate_dedicated_cpu = 0; |
| |
| idle_loop_epilog(in_purr); |
| |
| return index; |
| } |
| |
| static int shared_cede_loop(struct cpuidle_device *dev, |
| struct cpuidle_driver *drv, |
| int index) |
| { |
| unsigned long in_purr; |
| |
| idle_loop_prolog(&in_purr); |
| |
| /* |
| * 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(); |
| idle_loop_epilog(in_purr); |
| |
| return index; |
| } |
| |
| /* |
| * States for dedicated partition case. |
| */ |
| static struct cpuidle_state 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)) { |
| if (lppaca_shared_proc(get_lppaca())) { |
| cpuidle_state_table = shared_states; |
| max_idle_state = ARRAY_SIZE(shared_states); |
| } else { |
| cpuidle_state_table = dedicated_states; |
| max_idle_state = ARRAY_SIZE(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); |