/*
* 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/plpar_wrappers.h>
struct cpuidle_driver pseries_idle_driver = {
.name = "pseries_idle",
.owner = THIS_MODULE,
};
#define MAX_IDLE_STATE_COUNT 2
static int max_idle_state = MAX_IDLE_STATE_COUNT - 1;
static struct cpuidle_state *cpuidle_state_table;
static inline void idle_loop_prolog(unsigned long *in_purr)
{
*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;
}
static int snooze_loop(struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index)
{
unsigned long in_purr;
idle_loop_prolog(&in_purr);
local_irq_enable();
set_thread_flag(TIF_POLLING_NRFLAG);
while (!need_resched()) {
HMT_low();
HMT_very_low();
}
HMT_medium();
clear_thread_flag(TIF_POLLING_NRFLAG);
smp_mb();
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();
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();
idle_loop_epilog(in_purr);
return index;
}
/*
* States for dedicated partition case.
*/
static struct cpuidle_state dedicated_states[MAX_IDLE_STATE_COUNT] = {
{ /* Snooze */
.name = "snooze",
.desc = "snooze",
.flags = CPUIDLE_FLAG_TIME_VALID,
.exit_latency = 0,
.target_residency = 0,
.enter = &snooze_loop },
{ /* CEDE */
.name = "CEDE",
.desc = "CEDE",
.flags = CPUIDLE_FLAG_TIME_VALID,
.exit_latency = 10,
.target_residency = 100,
.enter = &dedicated_cede_loop },
};
/*
* States for shared partition case.
*/
static struct cpuidle_state shared_states[MAX_IDLE_STATE_COUNT] = {
{ /* Shared Cede */
.name = "Shared Cede",
.desc = "Shared Cede",
.flags = CPUIDLE_FLAG_TIME_VALID,
.exit_latency = 0,
.target_residency = 0,
.enter = &shared_cede_loop },
};
void update_smt_snooze_delay(int cpu, int residency)
{
struct cpuidle_driver *drv = cpuidle_get_driver();
struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);
if (cpuidle_state_table != dedicated_states)
return;
if (residency < 0) {
/* Disable the Nap state on that cpu */
if (dev)
dev->states_usage[1].disable = 1;
} else
if (drv)
drv->states[1].target_residency = residency;
}
static int pseries_cpuidle_add_cpu_notifier(struct notifier_block *n,
unsigned long action, void *hcpu)
{
int hotcpu = (unsigned long)hcpu;
struct cpuidle_device *dev =
per_cpu(cpuidle_devices, hotcpu);
if (dev && cpuidle_get_driver()) {
switch (action) {
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
cpuidle_pause_and_lock();
cpuidle_enable_device(dev);
cpuidle_resume_and_unlock();
break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
cpuidle_pause_and_lock();
cpuidle_disable_device(dev);
cpuidle_resume_and_unlock();
break;
default:
return NOTIFY_DONE;
}
}
return NOTIFY_OK;
}
static struct notifier_block setup_hotplug_notifier = {
.notifier_call = pseries_cpuidle_add_cpu_notifier,
};
/*
* 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_COUNT; ++idle_state) {
if (idle_state > max_idle_state)
break;
/* 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 (max_idle_state == 0) {
printk(KERN_DEBUG "pseries processor idle disabled.\n");
return -EPERM;
}
if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
if (lppaca_shared_proc(get_lppaca()))
cpuidle_state_table = shared_states;
else
cpuidle_state_table = dedicated_states;
} else
return -ENODEV;
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;
}
register_cpu_notifier(&setup_hotplug_notifier);
printk(KERN_DEBUG "pseries_idle_driver registered\n");
return 0;
}
device_initcall(pseries_processor_idle_init);
