diff options
Diffstat (limited to 'drivers/acpi/acpi_pad.c')
| -rw-r--r-- | drivers/acpi/acpi_pad.c | 502 |
1 files changed, 502 insertions, 0 deletions
diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c new file mode 100644 index 0000000000..7a453c5ff3 --- /dev/null +++ b/drivers/acpi/acpi_pad.c @@ -0,0 +1,502 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * acpi_pad.c ACPI Processor Aggregator Driver + * + * Copyright (c) 2009, Intel Corporation. + */ + +#include <linux/kernel.h> +#include <linux/cpumask.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/types.h> +#include <linux/kthread.h> +#include <uapi/linux/sched/types.h> +#include <linux/freezer.h> +#include <linux/cpu.h> +#include <linux/tick.h> +#include <linux/slab.h> +#include <linux/acpi.h> +#include <linux/perf_event.h> +#include <asm/mwait.h> +#include <xen/xen.h> + +#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad" +#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator" +#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80 +static DEFINE_MUTEX(isolated_cpus_lock); +static DEFINE_MUTEX(round_robin_lock); + +static unsigned long power_saving_mwait_eax; + +static unsigned char tsc_detected_unstable; +static unsigned char tsc_marked_unstable; + +static void power_saving_mwait_init(void) +{ + unsigned int eax, ebx, ecx, edx; + unsigned int highest_cstate = 0; + unsigned int highest_subcstate = 0; + int i; + + if (!boot_cpu_has(X86_FEATURE_MWAIT)) + return; + if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF) + return; + + cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx); + + if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) || + !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) + return; + + edx >>= MWAIT_SUBSTATE_SIZE; + for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) { + if (edx & MWAIT_SUBSTATE_MASK) { + highest_cstate = i; + highest_subcstate = edx & MWAIT_SUBSTATE_MASK; + } + } + power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) | + (highest_subcstate - 1); + +#if defined(CONFIG_X86) + switch (boot_cpu_data.x86_vendor) { + case X86_VENDOR_HYGON: + case X86_VENDOR_AMD: + case X86_VENDOR_INTEL: + case X86_VENDOR_ZHAOXIN: + case X86_VENDOR_CENTAUR: + /* + * AMD Fam10h TSC will tick in all + * C/P/S0/S1 states when this bit is set. + */ + if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) + tsc_detected_unstable = 1; + break; + default: + /* TSC could halt in idle */ + tsc_detected_unstable = 1; + } +#endif +} + +static unsigned long cpu_weight[NR_CPUS]; +static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1}; +static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS); +static void round_robin_cpu(unsigned int tsk_index) +{ + struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); + cpumask_var_t tmp; + int cpu; + unsigned long min_weight = -1; + unsigned long preferred_cpu; + + if (!alloc_cpumask_var(&tmp, GFP_KERNEL)) + return; + + mutex_lock(&round_robin_lock); + cpumask_clear(tmp); + for_each_cpu(cpu, pad_busy_cpus) + cpumask_or(tmp, tmp, topology_sibling_cpumask(cpu)); + cpumask_andnot(tmp, cpu_online_mask, tmp); + /* avoid HT sibilings if possible */ + if (cpumask_empty(tmp)) + cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus); + if (cpumask_empty(tmp)) { + mutex_unlock(&round_robin_lock); + free_cpumask_var(tmp); + return; + } + for_each_cpu(cpu, tmp) { + if (cpu_weight[cpu] < min_weight) { + min_weight = cpu_weight[cpu]; + preferred_cpu = cpu; + } + } + + if (tsk_in_cpu[tsk_index] != -1) + cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); + tsk_in_cpu[tsk_index] = preferred_cpu; + cpumask_set_cpu(preferred_cpu, pad_busy_cpus); + cpu_weight[preferred_cpu]++; + mutex_unlock(&round_robin_lock); + + set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu)); + + free_cpumask_var(tmp); +} + +static void exit_round_robin(unsigned int tsk_index) +{ + struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); + + cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); + tsk_in_cpu[tsk_index] = -1; +} + +static unsigned int idle_pct = 5; /* percentage */ +static unsigned int round_robin_time = 1; /* second */ +static int power_saving_thread(void *data) +{ + int do_sleep; + unsigned int tsk_index = (unsigned long)data; + u64 last_jiffies = 0; + + sched_set_fifo_low(current); + + while (!kthread_should_stop()) { + unsigned long expire_time; + + /* round robin to cpus */ + expire_time = last_jiffies + round_robin_time * HZ; + if (time_before(expire_time, jiffies)) { + last_jiffies = jiffies; + round_robin_cpu(tsk_index); + } + + do_sleep = 0; + + expire_time = jiffies + HZ * (100 - idle_pct) / 100; + + while (!need_resched()) { + if (tsc_detected_unstable && !tsc_marked_unstable) { + /* TSC could halt in idle, so notify users */ + mark_tsc_unstable("TSC halts in idle"); + tsc_marked_unstable = 1; + } + local_irq_disable(); + + perf_lopwr_cb(true); + + tick_broadcast_enable(); + tick_broadcast_enter(); + stop_critical_timings(); + + mwait_idle_with_hints(power_saving_mwait_eax, 1); + + start_critical_timings(); + tick_broadcast_exit(); + + perf_lopwr_cb(false); + + local_irq_enable(); + + if (time_before(expire_time, jiffies)) { + do_sleep = 1; + break; + } + } + + /* + * current sched_rt has threshold for rt task running time. + * When a rt task uses 95% CPU time, the rt thread will be + * scheduled out for 5% CPU time to not starve other tasks. But + * the mechanism only works when all CPUs have RT task running, + * as if one CPU hasn't RT task, RT task from other CPUs will + * borrow CPU time from this CPU and cause RT task use > 95% + * CPU time. To make 'avoid starvation' work, takes a nap here. + */ + if (unlikely(do_sleep)) + schedule_timeout_killable(HZ * idle_pct / 100); + + /* If an external event has set the need_resched flag, then + * we need to deal with it, or this loop will continue to + * spin without calling __mwait(). + */ + if (unlikely(need_resched())) + schedule(); + } + + exit_round_robin(tsk_index); + return 0; +} + +static struct task_struct *ps_tsks[NR_CPUS]; +static unsigned int ps_tsk_num; +static int create_power_saving_task(void) +{ + int rc; + + ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread, + (void *)(unsigned long)ps_tsk_num, + "acpi_pad/%d", ps_tsk_num); + + if (IS_ERR(ps_tsks[ps_tsk_num])) { + rc = PTR_ERR(ps_tsks[ps_tsk_num]); + ps_tsks[ps_tsk_num] = NULL; + } else { + rc = 0; + ps_tsk_num++; + } + + return rc; +} + +static void destroy_power_saving_task(void) +{ + if (ps_tsk_num > 0) { + ps_tsk_num--; + kthread_stop(ps_tsks[ps_tsk_num]); + ps_tsks[ps_tsk_num] = NULL; + } +} + +static void set_power_saving_task_num(unsigned int num) +{ + if (num > ps_tsk_num) { + while (ps_tsk_num < num) { + if (create_power_saving_task()) + return; + } + } else if (num < ps_tsk_num) { + while (ps_tsk_num > num) + destroy_power_saving_task(); + } +} + +static void acpi_pad_idle_cpus(unsigned int num_cpus) +{ + cpus_read_lock(); + + num_cpus = min_t(unsigned int, num_cpus, num_online_cpus()); + set_power_saving_task_num(num_cpus); + + cpus_read_unlock(); +} + +static uint32_t acpi_pad_idle_cpus_num(void) +{ + return ps_tsk_num; +} + +static ssize_t rrtime_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t count) +{ + unsigned long num; + + if (kstrtoul(buf, 0, &num)) + return -EINVAL; + if (num < 1 || num >= 100) + return -EINVAL; + mutex_lock(&isolated_cpus_lock); + round_robin_time = num; + mutex_unlock(&isolated_cpus_lock); + return count; +} + +static ssize_t rrtime_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%d\n", round_robin_time); +} +static DEVICE_ATTR_RW(rrtime); + +static ssize_t idlepct_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t count) +{ + unsigned long num; + + if (kstrtoul(buf, 0, &num)) + return -EINVAL; + if (num < 1 || num >= 100) + return -EINVAL; + mutex_lock(&isolated_cpus_lock); + idle_pct = num; + mutex_unlock(&isolated_cpus_lock); + return count; +} + +static ssize_t idlepct_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%d\n", idle_pct); +} +static DEVICE_ATTR_RW(idlepct); + +static ssize_t idlecpus_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t count) +{ + unsigned long num; + + if (kstrtoul(buf, 0, &num)) + return -EINVAL; + mutex_lock(&isolated_cpus_lock); + acpi_pad_idle_cpus(num); + mutex_unlock(&isolated_cpus_lock); + return count; +} + +static ssize_t idlecpus_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return cpumap_print_to_pagebuf(false, buf, + to_cpumask(pad_busy_cpus_bits)); +} + +static DEVICE_ATTR_RW(idlecpus); + +static int acpi_pad_add_sysfs(struct acpi_device *device) +{ + int result; + + result = device_create_file(&device->dev, &dev_attr_idlecpus); + if (result) + return -ENODEV; + result = device_create_file(&device->dev, &dev_attr_idlepct); + if (result) { + device_remove_file(&device->dev, &dev_attr_idlecpus); + return -ENODEV; + } + result = device_create_file(&device->dev, &dev_attr_rrtime); + if (result) { + device_remove_file(&device->dev, &dev_attr_idlecpus); + device_remove_file(&device->dev, &dev_attr_idlepct); + return -ENODEV; + } + return 0; +} + +static void acpi_pad_remove_sysfs(struct acpi_device *device) +{ + device_remove_file(&device->dev, &dev_attr_idlecpus); + device_remove_file(&device->dev, &dev_attr_idlepct); + device_remove_file(&device->dev, &dev_attr_rrtime); +} + +/* + * Query firmware how many CPUs should be idle + * return -1 on failure + */ +static int acpi_pad_pur(acpi_handle handle) +{ + struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL}; + union acpi_object *package; + int num = -1; + + if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer))) + return num; + + if (!buffer.length || !buffer.pointer) + return num; + + package = buffer.pointer; + + if (package->type == ACPI_TYPE_PACKAGE && + package->package.count == 2 && + package->package.elements[0].integer.value == 1) /* rev 1 */ + + num = package->package.elements[1].integer.value; + + kfree(buffer.pointer); + return num; +} + +static void acpi_pad_handle_notify(acpi_handle handle) +{ + int num_cpus; + uint32_t idle_cpus; + struct acpi_buffer param = { + .length = 4, + .pointer = (void *)&idle_cpus, + }; + + mutex_lock(&isolated_cpus_lock); + num_cpus = acpi_pad_pur(handle); + if (num_cpus < 0) { + mutex_unlock(&isolated_cpus_lock); + return; + } + acpi_pad_idle_cpus(num_cpus); + idle_cpus = acpi_pad_idle_cpus_num(); + acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m); + mutex_unlock(&isolated_cpus_lock); +} + +static void acpi_pad_notify(acpi_handle handle, u32 event, + void *data) +{ + struct acpi_device *device = data; + + switch (event) { + case ACPI_PROCESSOR_AGGREGATOR_NOTIFY: + acpi_pad_handle_notify(handle); + acpi_bus_generate_netlink_event(device->pnp.device_class, + dev_name(&device->dev), event, 0); + break; + default: + pr_warn("Unsupported event [0x%x]\n", event); + break; + } +} + +static int acpi_pad_add(struct acpi_device *device) +{ + acpi_status status; + + strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME); + strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS); + + if (acpi_pad_add_sysfs(device)) + return -ENODEV; + + status = acpi_install_notify_handler(device->handle, + ACPI_DEVICE_NOTIFY, acpi_pad_notify, device); + if (ACPI_FAILURE(status)) { + acpi_pad_remove_sysfs(device); + return -ENODEV; + } + + return 0; +} + +static void acpi_pad_remove(struct acpi_device *device) +{ + mutex_lock(&isolated_cpus_lock); + acpi_pad_idle_cpus(0); + mutex_unlock(&isolated_cpus_lock); + + acpi_remove_notify_handler(device->handle, + ACPI_DEVICE_NOTIFY, acpi_pad_notify); + acpi_pad_remove_sysfs(device); +} + +static const struct acpi_device_id pad_device_ids[] = { + {"ACPI000C", 0}, + {"", 0}, +}; +MODULE_DEVICE_TABLE(acpi, pad_device_ids); + +static struct acpi_driver acpi_pad_driver = { + .name = "processor_aggregator", + .class = ACPI_PROCESSOR_AGGREGATOR_CLASS, + .ids = pad_device_ids, + .ops = { + .add = acpi_pad_add, + .remove = acpi_pad_remove, + }, +}; + +static int __init acpi_pad_init(void) +{ + /* Xen ACPI PAD is used when running as Xen Dom0. */ + if (xen_initial_domain()) + return -ENODEV; + + power_saving_mwait_init(); + if (power_saving_mwait_eax == 0) + return -EINVAL; + + return acpi_bus_register_driver(&acpi_pad_driver); +} + +static void __exit acpi_pad_exit(void) +{ + acpi_bus_unregister_driver(&acpi_pad_driver); +} + +module_init(acpi_pad_init); +module_exit(acpi_pad_exit); +MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>"); +MODULE_DESCRIPTION("ACPI Processor Aggregator Driver"); +MODULE_LICENSE("GPL"); |