blob: 6513ef2af66a81564dfb18310bbe84c0e225fea1 [file] [log] [blame]
// 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/idle.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 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
}
}
static int dedicated_cede_loop(struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index)
{
pseries_idle_prolog();
get_lppaca()->donate_dedicated_cpu = 1;
HMT_medium();
check_and_cede_processor();
local_irq_disable();
get_lppaca()->donate_dedicated_cpu = 0;
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[] = {
{ /* 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 = 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);