https://github.com/torvalds/linux
Tip revision: 54ecb8f7028c5eb3d740bb82b0f1d90f2df63c5c authored by Linus Torvalds on 30 September 2019, 17:35:40 UTC
Linux 5.4-rc1
Linux 5.4-rc1
Tip revision: 54ecb8f
cpuidle-powernv.c
// SPDX-License-Identifier: GPL-2.0
/*
* cpuidle-powernv - idle state cpuidle driver.
* Adapted from drivers/cpuidle/cpuidle-pseries
*
*/
#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 <linux/clockchips.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <asm/machdep.h>
#include <asm/firmware.h>
#include <asm/opal.h>
#include <asm/runlatch.h>
#include <asm/cpuidle.h>
/*
* Expose only those Hardware idle states via the cpuidle framework
* that have latency value below POWERNV_THRESHOLD_LATENCY_NS.
*/
#define POWERNV_THRESHOLD_LATENCY_NS 200000
static struct cpuidle_driver powernv_idle_driver = {
.name = "powernv_idle",
.owner = THIS_MODULE,
};
static int max_idle_state __read_mostly;
static struct cpuidle_state *cpuidle_state_table __read_mostly;
struct stop_psscr_table {
u64 val;
u64 mask;
};
static struct stop_psscr_table stop_psscr_table[CPUIDLE_STATE_MAX] __read_mostly;
static u64 default_snooze_timeout __read_mostly;
static bool snooze_timeout_en __read_mostly;
static u64 get_snooze_timeout(struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index)
{
int i;
if (unlikely(!snooze_timeout_en))
return default_snooze_timeout;
for (i = index + 1; i < drv->state_count; i++) {
struct cpuidle_state *s = &drv->states[i];
struct cpuidle_state_usage *su = &dev->states_usage[i];
if (s->disabled || su->disable)
continue;
return s->target_residency * tb_ticks_per_usec;
}
return default_snooze_timeout;
}
static int snooze_loop(struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index)
{
u64 snooze_exit_time;
set_thread_flag(TIF_POLLING_NRFLAG);
local_irq_enable();
snooze_exit_time = get_tb() + get_snooze_timeout(dev, drv, index);
ppc64_runlatch_off();
HMT_very_low();
while (!need_resched()) {
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();
ppc64_runlatch_on();
clear_thread_flag(TIF_POLLING_NRFLAG);
local_irq_disable();
return index;
}
static int nap_loop(struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index)
{
power7_idle_type(PNV_THREAD_NAP);
return index;
}
/* Register for fastsleep only in oneshot mode of broadcast */
#ifdef CONFIG_TICK_ONESHOT
static int fastsleep_loop(struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index)
{
unsigned long old_lpcr = mfspr(SPRN_LPCR);
unsigned long new_lpcr;
if (unlikely(system_state < SYSTEM_RUNNING))
return index;
new_lpcr = old_lpcr;
/* Do not exit powersave upon decrementer as we've setup the timer
* offload.
*/
new_lpcr &= ~LPCR_PECE1;
mtspr(SPRN_LPCR, new_lpcr);
power7_idle_type(PNV_THREAD_SLEEP);
mtspr(SPRN_LPCR, old_lpcr);
return index;
}
#endif
static int stop_loop(struct cpuidle_device *dev,
struct cpuidle_driver *drv,
int index)
{
power9_idle_type(stop_psscr_table[index].val,
stop_psscr_table[index].mask);
return index;
}
/*
* States for dedicated partition case.
*/
static struct cpuidle_state powernv_states[CPUIDLE_STATE_MAX] = {
{ /* Snooze */
.name = "snooze",
.desc = "snooze",
.exit_latency = 0,
.target_residency = 0,
.enter = snooze_loop },
};
static int powernv_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 powernv_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;
}
/*
* powernv_cpuidle_driver_init()
*/
static int powernv_cpuidle_driver_init(void)
{
int idle_state;
struct cpuidle_driver *drv = &powernv_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;
}
/*
* On the PowerNV platform cpu_present may be less than cpu_possible in
* cases when firmware detects the CPU, but it is not available to the
* OS. If CONFIG_HOTPLUG_CPU=n, then such CPUs are not hotplugable at
* run time and hence cpu_devices are not created for those CPUs by the
* generic topology_init().
*
* drv->cpumask defaults to cpu_possible_mask in
* __cpuidle_driver_init(). This breaks cpuidle on PowerNV where
* cpu_devices are not created for CPUs in cpu_possible_mask that
* cannot be hot-added later at run time.
*
* Trying cpuidle_register_device() on a CPU without a cpu_device is
* incorrect, so pass a correct CPU mask to the generic cpuidle driver.
*/
drv->cpumask = (struct cpumask *)cpu_present_mask;
return 0;
}
static inline void add_powernv_state(int index, const char *name,
unsigned int flags,
int (*idle_fn)(struct cpuidle_device *,
struct cpuidle_driver *,
int),
unsigned int target_residency,
unsigned int exit_latency,
u64 psscr_val, u64 psscr_mask)
{
strlcpy(powernv_states[index].name, name, CPUIDLE_NAME_LEN);
strlcpy(powernv_states[index].desc, name, CPUIDLE_NAME_LEN);
powernv_states[index].flags = flags;
powernv_states[index].target_residency = target_residency;
powernv_states[index].exit_latency = exit_latency;
powernv_states[index].enter = idle_fn;
/* For power8 and below psscr_* will be 0 */
stop_psscr_table[index].val = psscr_val;
stop_psscr_table[index].mask = psscr_mask;
}
/*
* Returns 0 if prop1_len == prop2_len. Else returns -1
*/
static inline int validate_dt_prop_sizes(const char *prop1, int prop1_len,
const char *prop2, int prop2_len)
{
if (prop1_len == prop2_len)
return 0;
pr_warn("cpuidle-powernv: array sizes don't match for %s and %s\n",
prop1, prop2);
return -1;
}
extern u32 pnv_get_supported_cpuidle_states(void);
static int powernv_add_idle_states(void)
{
int nr_idle_states = 1; /* Snooze */
int dt_idle_states;
u32 has_stop_states = 0;
int i;
u32 supported_flags = pnv_get_supported_cpuidle_states();
/* Currently we have snooze statically defined */
if (nr_pnv_idle_states <= 0) {
pr_warn("cpuidle-powernv : Only Snooze is available\n");
goto out;
}
/* TODO: Count only states which are eligible for cpuidle */
dt_idle_states = nr_pnv_idle_states;
/*
* Since snooze is used as first idle state, max idle states allowed is
* CPUIDLE_STATE_MAX -1
*/
if (nr_pnv_idle_states > CPUIDLE_STATE_MAX - 1) {
pr_warn("cpuidle-powernv: discovered idle states more than allowed");
dt_idle_states = CPUIDLE_STATE_MAX - 1;
}
/*
* If the idle states use stop instruction, probe for psscr values
* and psscr mask which are necessary to specify required stop level.
*/
has_stop_states = (pnv_idle_states[0].flags &
(OPAL_PM_STOP_INST_FAST | OPAL_PM_STOP_INST_DEEP));
for (i = 0; i < dt_idle_states; i++) {
unsigned int exit_latency, target_residency;
bool stops_timebase = false;
struct pnv_idle_states_t *state = &pnv_idle_states[i];
/*
* Skip the platform idle state whose flag isn't in
* the supported_cpuidle_states flag mask.
*/
if ((state->flags & supported_flags) != state->flags)
continue;
/*
* If an idle state has exit latency beyond
* POWERNV_THRESHOLD_LATENCY_NS then don't use it
* in cpu-idle.
*/
if (state->latency_ns > POWERNV_THRESHOLD_LATENCY_NS)
continue;
/*
* Firmware passes residency and latency values in ns.
* cpuidle expects it in us.
*/
exit_latency = DIV_ROUND_UP(state->latency_ns, 1000);
target_residency = DIV_ROUND_UP(state->residency_ns, 1000);
if (has_stop_states && !(state->valid))
continue;
if (state->flags & OPAL_PM_TIMEBASE_STOP)
stops_timebase = true;
if (state->flags & OPAL_PM_NAP_ENABLED) {
/* Add NAP state */
add_powernv_state(nr_idle_states, "Nap",
CPUIDLE_FLAG_NONE, nap_loop,
target_residency, exit_latency, 0, 0);
} else if (has_stop_states && !stops_timebase) {
add_powernv_state(nr_idle_states, state->name,
CPUIDLE_FLAG_NONE, stop_loop,
target_residency, exit_latency,
state->psscr_val,
state->psscr_mask);
}
/*
* All cpuidle states with CPUIDLE_FLAG_TIMER_STOP set must come
* within this config dependency check.
*/
#ifdef CONFIG_TICK_ONESHOT
else if (state->flags & OPAL_PM_SLEEP_ENABLED ||
state->flags & OPAL_PM_SLEEP_ENABLED_ER1) {
/* Add FASTSLEEP state */
add_powernv_state(nr_idle_states, "FastSleep",
CPUIDLE_FLAG_TIMER_STOP,
fastsleep_loop,
target_residency, exit_latency, 0, 0);
} else if (has_stop_states && stops_timebase) {
add_powernv_state(nr_idle_states, state->name,
CPUIDLE_FLAG_TIMER_STOP, stop_loop,
target_residency, exit_latency,
state->psscr_val,
state->psscr_mask);
}
#endif
else
continue;
nr_idle_states++;
}
out:
return nr_idle_states;
}
/*
* powernv_idle_probe()
* Choose state table for shared versus dedicated partition
*/
static int powernv_idle_probe(void)
{
if (cpuidle_disable != IDLE_NO_OVERRIDE)
return -ENODEV;
if (firmware_has_feature(FW_FEATURE_OPAL)) {
cpuidle_state_table = powernv_states;
/* Device tree can indicate more idle states */
max_idle_state = powernv_add_idle_states();
default_snooze_timeout = TICK_USEC * tb_ticks_per_usec;
if (max_idle_state > 1)
snooze_timeout_en = true;
} else
return -ENODEV;
return 0;
}
static int __init powernv_processor_idle_init(void)
{
int retval;
retval = powernv_idle_probe();
if (retval)
return retval;
powernv_cpuidle_driver_init();
retval = cpuidle_register(&powernv_idle_driver, NULL);
if (retval) {
printk(KERN_DEBUG "Registration of powernv driver failed.\n");
return retval;
}
retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
"cpuidle/powernv:online",
powernv_cpuidle_cpu_online, NULL);
WARN_ON(retval < 0);
retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD,
"cpuidle/powernv:dead", NULL,
powernv_cpuidle_cpu_dead);
WARN_ON(retval < 0);
printk(KERN_DEBUG "powernv_idle_driver registered\n");
return 0;
}
device_initcall(powernv_processor_idle_init);