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/*
* Copyright (c) 2018 Intel Corporation.
* Copyright (c) 2022 Nordic Semiconductor ASA
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <zephyr/kernel.h>
#include <zephyr/pm/pm.h>
#include <zephyr/pm/policy.h>
#include <zephyr/spinlock.h>
#include <zephyr/sys_clock.h>
#include <zephyr/sys/__assert.h>
#include <zephyr/sys/time_units.h>
#include <zephyr/sys/atomic.h>
#include <zephyr/toolchain.h>
#define DT_SUB_LOCK_INIT(node_id) \
{ .state = PM_STATE_DT_INIT(node_id), \
.substate_id = DT_PROP_OR(node_id, substate_id, 0), \
.lock = ATOMIC_INIT(0), \
},
/**
* State and substate lock structure.
*
* This struct is associating a reference counting to each <state,substate>
* couple to be used with the pm_policy_substate_lock_* functions.
*
* Operations on this array are in the order of O(n) with the number of power
* states and this is mostly due to the random nature of the substate value
* (that can be anything from a small integer value to a bitmask). We can
* probably do better with an hashmap.
*/
static struct {
enum pm_state state;
uint8_t substate_id;
atomic_t lock;
} substate_lock_t[] = {
DT_FOREACH_STATUS_OKAY(zephyr_power_state, DT_SUB_LOCK_INIT)
};
/** Lock to synchronize access to the latency request list. */
static struct k_spinlock latency_lock;
/** List of maximum latency requests. */
static sys_slist_t latency_reqs;
/** Maximum CPU latency in us */
static int32_t max_latency_us = SYS_FOREVER_US;
/** Maximum CPU latency in cycles */
static int32_t max_latency_cyc = -1;
/** List of latency change subscribers. */
static sys_slist_t latency_subs;
/** Lock to synchronize access to the events list. */
static struct k_spinlock events_lock;
/** List of events. */
static sys_slist_t events_list;
/** Next event, in absolute cycles (<0: none, [0, UINT32_MAX]: cycles) */
static int64_t next_event_cyc = -1;
/** @brief Update maximum allowed latency. */
static void update_max_latency(void)
{
int32_t new_max_latency_us = SYS_FOREVER_US;
struct pm_policy_latency_request *req;
SYS_SLIST_FOR_EACH_CONTAINER(&latency_reqs, req, node) {
if ((new_max_latency_us == SYS_FOREVER_US) ||
((int32_t)req->value_us < new_max_latency_us)) {
new_max_latency_us = (int32_t)req->value_us;
}
}
if (max_latency_us != new_max_latency_us) {
struct pm_policy_latency_subscription *sreq;
int32_t new_max_latency_cyc = -1;
SYS_SLIST_FOR_EACH_CONTAINER(&latency_subs, sreq, node) {
sreq->cb(new_max_latency_us);
}
if (new_max_latency_us != SYS_FOREVER_US) {
new_max_latency_cyc = (int32_t)k_us_to_cyc_ceil32(new_max_latency_us);
}
max_latency_us = new_max_latency_us;
max_latency_cyc = new_max_latency_cyc;
}
}
/** @brief Update next event. */
static void update_next_event(uint32_t cyc)
{
int64_t new_next_event_cyc = -1;
struct pm_policy_event *evt;
SYS_SLIST_FOR_EACH_CONTAINER(&events_list, evt, node) {
uint64_t cyc_evt = evt->value_cyc;
/*
* cyc value is a 32-bit rolling counter:
*
* |---------------->-----------------------|
* 0 cyc UINT32_MAX
*
* Values from [0, cyc) are events happening later than
* [cyc, UINT32_MAX], so pad [0, cyc) with UINT32_MAX + 1 to do
* the comparison.
*/
if (cyc_evt < cyc) {
cyc_evt += UINT32_MAX + 1U;
}
if ((new_next_event_cyc < 0) ||
(cyc_evt < new_next_event_cyc)) {
new_next_event_cyc = cyc_evt;
}
}
/* undo padding for events in the [0, cyc) range */
if (new_next_event_cyc > UINT32_MAX) {
new_next_event_cyc -= UINT32_MAX + 1U;
}
next_event_cyc = new_next_event_cyc;
}
#ifdef CONFIG_PM_POLICY_DEFAULT
const struct pm_state_info *pm_policy_next_state(uint8_t cpu, int32_t ticks)
{
int64_t cyc = -1;
uint8_t num_cpu_states;
const struct pm_state_info *cpu_states;
if (ticks != K_TICKS_FOREVER) {
cyc = k_ticks_to_cyc_ceil32(ticks);
}
num_cpu_states = pm_state_cpu_get_all(cpu, &cpu_states);
if (next_event_cyc >= 0) {
uint32_t cyc_curr = k_cycle_get_32();
int64_t cyc_evt = next_event_cyc - cyc_curr;
/* event happening after cycle counter max value, pad */
if (next_event_cyc <= cyc_curr) {
cyc_evt += UINT32_MAX;
}
if (cyc_evt > 0) {
/* if there's no system wakeup event always wins,
* otherwise, who comes earlier wins
*/
if (cyc < 0) {
cyc = cyc_evt;
} else {
cyc = MIN(cyc, cyc_evt);
}
}
}
for (int16_t i = (int16_t)num_cpu_states - 1; i >= 0; i--) {
const struct pm_state_info *state = &cpu_states[i];
uint32_t min_residency_cyc, exit_latency_cyc;
/* check if there is a lock on state + substate */
if (pm_policy_state_lock_is_active(state->state, state->substate_id)) {
continue;
}
min_residency_cyc = k_us_to_cyc_ceil32(state->min_residency_us);
exit_latency_cyc = k_us_to_cyc_ceil32(state->exit_latency_us);
/* skip state if it brings too much latency */
if ((max_latency_cyc >= 0) &&
(exit_latency_cyc >= max_latency_cyc)) {
continue;
}
if ((cyc < 0) ||
(cyc >= (min_residency_cyc + exit_latency_cyc))) {
return state;
}
}
return NULL;
}
#endif
void pm_policy_state_lock_get(enum pm_state state, uint8_t substate_id)
{
for (size_t i = 0; i < ARRAY_SIZE(substate_lock_t); i++) {
if (substate_lock_t[i].state == state &&
(substate_lock_t[i].substate_id == substate_id ||
substate_id == PM_ALL_SUBSTATES)) {
atomic_inc(&substate_lock_t[i].lock);
}
}
}
void pm_policy_state_lock_put(enum pm_state state, uint8_t substate_id)
{
for (size_t i = 0; i < ARRAY_SIZE(substate_lock_t); i++) {
if (substate_lock_t[i].state == state &&
(substate_lock_t[i].substate_id == substate_id ||
substate_id == PM_ALL_SUBSTATES)) {
atomic_t cnt = atomic_dec(&substate_lock_t[i].lock);
ARG_UNUSED(cnt);
__ASSERT(cnt >= 1, "Unbalanced state lock get/put");
}
}
}
bool pm_policy_state_lock_is_active(enum pm_state state, uint8_t substate_id)
{
for (size_t i = 0; i < ARRAY_SIZE(substate_lock_t); i++) {
if (substate_lock_t[i].state == state &&
(substate_lock_t[i].substate_id == substate_id ||
substate_id == PM_ALL_SUBSTATES)) {
return (atomic_get(&substate_lock_t[i].lock) != 0);
}
}
return false;
}
void pm_policy_latency_request_add(struct pm_policy_latency_request *req,
uint32_t value_us)
{
req->value_us = value_us;
k_spinlock_key_t key = k_spin_lock(&latency_lock);
sys_slist_append(&latency_reqs, &req->node);
update_max_latency();
k_spin_unlock(&latency_lock, key);
}
void pm_policy_latency_request_update(struct pm_policy_latency_request *req,
uint32_t value_us)
{
k_spinlock_key_t key = k_spin_lock(&latency_lock);
req->value_us = value_us;
update_max_latency();
k_spin_unlock(&latency_lock, key);
}
void pm_policy_latency_request_remove(struct pm_policy_latency_request *req)
{
k_spinlock_key_t key = k_spin_lock(&latency_lock);
(void)sys_slist_find_and_remove(&latency_reqs, &req->node);
update_max_latency();
k_spin_unlock(&latency_lock, key);
}
void pm_policy_latency_changed_subscribe(struct pm_policy_latency_subscription *req,
pm_policy_latency_changed_cb_t cb)
{
k_spinlock_key_t key = k_spin_lock(&latency_lock);
req->cb = cb;
sys_slist_append(&latency_subs, &req->node);
k_spin_unlock(&latency_lock, key);
}
void pm_policy_latency_changed_unsubscribe(struct pm_policy_latency_subscription *req)
{
k_spinlock_key_t key = k_spin_lock(&latency_lock);
(void)sys_slist_find_and_remove(&latency_subs, &req->node);
k_spin_unlock(&latency_lock, key);
}
void pm_policy_event_register(struct pm_policy_event *evt, uint32_t time_us)
{
k_spinlock_key_t key = k_spin_lock(&events_lock);
uint32_t cyc = k_cycle_get_32();
evt->value_cyc = cyc + k_us_to_cyc_ceil32(time_us);
sys_slist_append(&events_list, &evt->node);
update_next_event(cyc);
k_spin_unlock(&events_lock, key);
}
void pm_policy_event_update(struct pm_policy_event *evt, uint32_t time_us)
{
k_spinlock_key_t key = k_spin_lock(&events_lock);
uint32_t cyc = k_cycle_get_32();
evt->value_cyc = cyc + k_us_to_cyc_ceil32(time_us);
update_next_event(cyc);
k_spin_unlock(&events_lock, key);
}
void pm_policy_event_unregister(struct pm_policy_event *evt)
{
k_spinlock_key_t key = k_spin_lock(&events_lock);
(void)sys_slist_find_and_remove(&events_list, &evt->node);
update_next_event(k_cycle_get_32());
k_spin_unlock(&events_lock, key);
}